Core Technology Manual

©Ricoh CO., LTD., All rights reserved.

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CONTENTS

• Introduction

• Handling Paper

• Photocopying Processes

• Digital Processes

• Facsimile Processes

• Process Control

• Color Processes

• Digital Duplicators

• Standard Components

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Purpose and Scope

What is it for?

The Core Technology Manual is a reference source for standard technologies used in Ricoh officeproducts. It has three main intended uses.

1. Support for Service Manuals

Instead of repeating a common technical description, a service manual can refer to the descriptionof the process in the Core Technology Manual. Or the service manual can refer the reader to theCore Technology Manual for additional information. Thus service manuals can be made morecompact and more focused on the target machine.

2. General Technical Reference

Technical staff and field service personnel can use this manual as a standard technical referenceabout Ricoh office machines. It may be especially useful as a memory refresher concerning thetechnical aspects of the various products that are often encountered in the field.

3. Source for Training Material

This manual can be used as a source of background material when preparing technical trainingcourses.

Purpose and ScopeHow to use this manual

9 August 2003 Page 2

Introduction How to use this manual

Scope

While the Core Technology Manual can be studied, it is intended primarily for use as a reference. Itdoesn’t cover all technical aspects of Ricoh office products. Instead, it concentrates on the commontechnologies used in many products. Generally, leading edge technology and machine specifictechnology will not be covered.

This manual will be updated from time to time as technology evolves and field needs change.

How to use this manual

The Portable Document FormatThis manual is a PDF (portable document format) file, and you must use Acrobat Reader or AcrobatExplorer to view it. We assume that you are familiar with the features of Adobe Acrobat. If not,please take a few minutes to familiarize yourself with Acrobat’s navigation features. To make bestuse of this and other electronic documents, you need to know how to use the navigation buttons,bookmarks, thumbnails, and searching functions. (Acrobat comes with several reference and tutorialdocuments that you can use to “book up” on Acrobat.)


Introduction How to use this manual

NavigatingThis manual has numerous links that allow you to quickly jump to related information. The links areindicated by green italic text. Also, this manual is heavily bookmarked. You can get almost anywhereyou need to by “drilling down” through the bookmarks. In addition the manual is fully indexed; so, youcan use Acrobat’s full text search function to locate items by keyword searches.

Printing this manual

This manual is formatted for screen viewing. The actual formatted size is A5; however, if you print toA5 paper, some of the image may be cut at the margins depending on the capabilities of the printer.If this happens, print to a slightly larger size paper. ISO B5 and JIS B5 work well. As colors are usedin this manual you will get better results by using a color printer.


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Overview

For most machines, paper handling can be broken into six main procedures: feed, registration,transport, duplexing, misfeed detection and finishing. Originals are handled in a similar, thoughseparate, fashion.

Paper handling begins at the paper source—this could be a paper tray, cassette, roll, or a single,hand-fed sheet in the by-pass tray. The paper feed process ensures that the paper is positioned andready for use. It also feeds the paper into the main unit, and separates sheets of paper so that onlyone sheet is fed at a time.

Registration ensures that each sheet is positioned properly for printing. Registration typicallyaddresses two issues: timing and skew. For timing, it synchronizes the image on the photoconductorwith the paper. It ensures that the leading edge of the paper matches the leading edge of thedeveloped image. Meanwhile, skew control ensures that the paper is lined up straight. Itcompensates for slight rotations to the paper during paper feed.

OverviewPaper PathPaper FeedRegistrationPaper TransportDuplexingMisfeed DetectionHandling OriginalsHandling Finished Copies/Prints


Handling Paper Paper Path

Paper transport is merely moving the paper. Paper is usually transported from paper feed toregistration, from paper separation to fusing, and from fusing to the finisher or output tray.

Not all machines are capable of double-sided printing; however, those that are must have some typeof duplex unit. The duplex process redirects the paper, allowing information to be printed on bothsides of a single sheet. For duplexing, paper can be handled either inside the main unit or usingexternal duplex units.

Misfeed detection uses a combination of sensors along the paper path to track the progress of eachsheet of paper. These sensors help detect paper jams, determining when and where a jam takesplace

Finally, after they are printed, the sheets can be stacked, sorted, directed to various output trays orbins, stapled, punched, or otherwise processed. Finishing processes can take place inside the mainunit itself or can be handled by a finishing unit.

Paper Path

The paper path is, basically, the path that the paper travels from the paper source to the output tray.Most machines have a branching paper path—the paper can come from more than one source, andcan be directed to more than one finishing process or output tray. Most paper paths can run throughall six processes. There are two basic designs for the paper path. Most machines use a variation ofthese.



Vertical Path

Here, the paper is stored in the lowerportion of the machine. Each sheet is fedfrom the paper source, transportedvertically up the machine, then fed to theregistration rollers and developmentsection. Sometimes a shorter, straight pathruns from the by-pass tray, this can beused to handle paper stocks that cannotrun through the main paper path.Duplexing is handled through either aninternal, horizontal duplexing unit or anexternal, vertical duplexing unit.

The illustration shows the A265. Paper isstored in paper trays or fed in the by-passtray. The copier uses an external duplexingunit. Finished sheets can be routed to avariety of output trays or to the finisher.Note: in this machine even thedevelopment unit and fusing unit are vertical. The horizontal path across the top of the machine ismerely to transport sheets to the finisher. Also, this copier does not provide a straight paper pathfrom the by-pass tray. This layout is used in many new copiers and multifunction products.



Horizontal Path

Here the paper travels a generallyhorizontal path from the papersource to the finisher or output tray.A straight, horizontal paper pathreduces the likelihood of paperjams. It may also improve speed, orto allow a wider variety of paperstocks—particularly heavier paperstocks.

In some color machines, adevelopment process calledtetradrive uses a horizontal path.Four development units are placedin a line. This provides quick, highquality color printing.

Unfortunately, the horizontal paper path is not as compact as the vertical path. These machines tendto be larger.

The illustration above shows the A294. Paper from the LCT follows a traditional, horizontal paperpath. However, paper from the main unit’s trays follows a largely vertical transport path. (Purehorizontal systems have become quite rare.) Also, unlike the A265, the copy processes are alignedhorizontally. This machine also includes a finisher and an internal, horizontal duplex unit.


Handling Paper Paper Feed

Paper FeedPaper feed is the separation of a single sheet of paper from a paper source—usually a stack ofpaper in a cassette or tray—and moving it into the machine.

Paper Feed Methods

Feed and Reverse Roller (FRR)The FRR feed mechanism consists of a pick-uproller, a feed roller, and a reverse roller.

The pick-up roller [A] is not in contact with thepaper stack before it starts feeding paper.Shortly after the start key is pressed, the pick-uproller drops down and feeds the top sheetbetween the feed roller [B] and the reverse roller[C]. At almost the same time that the paper’sleading edge arrives at the feed roller, the pick-up roller lifts off the paper stack so that it doesnot interfere with the operation of the feed andreverse rollers. The feed and reverse rollersthen take over the paper feed process.

frr1.jpg



There is a one-way bearing inside the feed roller so it can turn onlyin one direction. The reverse roller turns in the opposite direction asthe feed roller. A slip clutch (torque limiter clutch) drives the reverseroller, however, allowing it to turn in either direction depending onthe friction between the rollers. A spring keeps the reverse roller incontact with the feed roller.

The direction that the reverse roller [A] turns depends on thefrictional forces acting on it. The slip clutch applies a constantclockwise force (F1). When there is a single sheet of paper being

driven between the rollers, the force of friction between the feedroller [B] and the paper (F2) is greater than F1. So, the reverseroller turns counterclockwise.

If two or more sheets are fed between the rollers, the forward forceon the second sheet (F3), becomes less than F1 because the lowcoefficient of friction between the two sheets. So, the reverse rollerstarts turning clockwise and drives the second sheet back to thecassette.

frr2.tif

frr3.tif



Example: Model A113

Drive Mechanism

The paper feed unit consists of a pick-up roller [A],feed roller [B], separation roller [C], relay roller [D],pick-up solenoid [E], separation solenoid [F],paper upper limit sensor [G], and paper endsensor [H].

The main motor drives the pick-up, feed, andseparation rollers via the timing belt [I] and thepaper feed clutch [J]. The main motor also drivesthe relay roller. However, drive is transmitted tothe relay roller via the relay clutch [K] and thetiming belt [L].

In stand-by mode, the separation roller is awayfrom the feed roller. 50 ms after pressing the startkey, the main motor and the separation solenoidturn on. Then the separation roller comes incontact with the feed roller. 100 ms after the mainmotor starts to rotate, the pick-up solenoid turnson. The pick-up roller lowers to make contact withthe top of the paper stack. The pick-up solenoidstays on for 550 ms.

frr4.tif



200 ms after the main motor starts to rotate, thepaper feed clutch and the relay clutch turn on. Thefeed roller and relay rollers feed the top sheet ofthe paper stack to the registration rollers. Whenthe leading edge of the paper passes through theupper relay sensor, the paper feed clutch is de-energized.

frr5.tif



Slip-clutch Mechanism

The separation roller is mounted on a slip clutch.The slip clutch [A] consists of an input hub [B] andan output hub [C], which also acts as the case ofthe clutch. A magnetic ring [D] and steel spacers[E] are fitted onto the input hub. A ferrite ring [F] isfitted into the output hub. Ferrite powder [G]packed between the magnetic ring and the ferritering generates a constant torque due to magneticforce. The input hub and the output hub slip whenthe rotational force exceeds this constant torque.The constant torque prevents double feeding,because it exceeds the coefficient of frictionbetween sheets of paper. This type of slip clutchdoes not require lubrication.

frr6.tif



Friction PadThe friction pad mechanism has two principlecomponents—the paper feed roller [A] and a frictionpad [B].

When the paper feed roller rotates, it feeds the topsheet of paper. The second sheet also tries to feed,but because the friction force between the friction padand the second sheet is greater than that between thefirst and second sheets, the first sheet of paper is theonly one that feeds.

The friction coefficient applied to the surface of eachsheet of paper is shown below.

020117.tif

[A]

[B]

0201 18. tifµ1>µ2>µ3



Example: Model A074

When the paper tray is placed in the copier, itpushes the pressure release lever [A], causing itto turn clockwise. This then causes the frictionpad holder [B], holding the friction pad, to pressup against the paper feed roller [C]. The frictionpad pressure against the paper feed roller isdetermined by the friction pad pressure spring[D]. This pressure is applied evenly to the paperfeed roller because the friction pad holder ismounted on the mounting bracket [E] with aswivel bushing.

fricpad.tif



Friction rollerThe paper separation mechanism for the friction roller usesthe same principles as the paper separation method for thefriction pad.

The two main components are the paper feed roller and thefriction roller. When the paper feed roller rotates, the topsheet of paper is fed. The second sheet also tries to feed, butas the friction force between the friction roller and the secondsheet is greater than that between the first and secondsheets, only the first sheet of paper is fed.

fricroll1.tif



Example: Model A133 Duplex

The duplex paper feed system consists of threesets of duplex feed rollers and a friction roller [A].The friction roller has a one-way bearing inside;therefore, it rotates freely during paper stackingand locks during paper feeding. The duplex feedrollers can only feed the top sheet of the stackbecause the friction roller functions in the sameway as a friction pad does.

a133d587.wmf

[A]



Separation BeltThe separation belt system (also called the“friction belt” system) primarily feeds sheets fromthe bottom of a stack. It is commonly employed inautomatic document feeders (ADFs) and induplexing systems.

The separation belt feed mechanism is similar tothe friction pad and friction roller systems; itexploits the difference in friction resistance toseparate a single sheet of paper. However, unlikethese two systems, the separation belt does notpassively resist the passage of extra sheets ofpaper; it turns against the movement of the paperto feed back all but the bottom sheet.

The mechanism shown to the right is from theDF62.

[A] Separation belts

[B] Feed rollersA610d506.wmf

[B]

[A]



Example: Model A095 Duplex

The illustrations to the right show the model A095duplex paper feed mechanism.

The paper on the duplex tray feeds in order fromthe bottom to the top sheet. After all copies arestacked on the duplex tray, the duplex pressuresolenoid [A] turns on to lower the pressure arm [B]causing the pressure arm to press the paperagainst the pick-up roller [C].

Then, the paper feed clutch [D] turns on to rotatethe pick-up roller, separation belts [E] and thefeed roller [F]. The separation belts and the feedroller rotate in opposite directions.

Only the bottom sheet is fed because theseparation belt prevents any other sheets fromfeeding.

sepbelt1.wmf

[B]

[E]

[A]

sepbelt2.wmf

[C]

[D]

[F]

[B]

[E]



Separation TabThe separation tab separation system is avariation of the separation belt system. It is usedin slower feeding ADF units.

The illustration shows a document feeder using aseparation tab. The pick-up roller [A] and feedroller [B] feed the document into the ADF unit.Only the bottom sheet is fed because theseparation tab [C] prevents any other sheets fromfeeding. The document feed-in roller [D], feeds thedocument through the ADF unit.

g025d504.wmf[B]

[C]

[D]

[A]



Corner SeparatorCorner separators provide a simple and reliablemethod of separating off the top sheet duringpaper feed. Commonly, they are used along withsemicircular feed rollers in low and medium speedcopiers.

A spring [A] holds the paper stack up against theunderside of the corner separators [B]. As thefeed rollers [C] start forcing the paper forward, thecorner separators retard the movement of thepaper causing the top sheet to bow up at theedges and thus separate from the lower sheets.With further feeding, the corners of the top sheetrelease from the corner separators. The top sheetthen feeds into the paper path while the cornerseparators stop the lower sheets from feeding.

cor_sep.tif

[B][C]

[A]



Example: Model A219

This copier has one paper feed station and a by-pass feed table. The paper feed station uses apaper tray [A] that can hold 500 sheets. The by-pass feed table [B] can hold 80 sheets.

The paper tray uses two semicircular feed rollers[C] and corner separators. The semicircular feedrollers make one rotation to drive the top sheet ofthe paper stack to the relay rollers [D]. The twocorner separators allow only one sheet to feed.They also hold the paper stack. When the papertray is drawn out of the machine, the springpressure is released, and the tray bottom platedrops. In addition, there is no need to press thebottom plate down when putting the tray back in.

The by-pass feed table uses a feed roller andfriction pad system to feed the top sheet of paperto the registration rollers. cor_sep2.tif



Air KnifeThe air knife paper feed process uses jets of air toseparate sheets of paper for paper feed. The airknife method (also called “air separation” method)is suitable for high speed copying and printingsystems because it reduces the feed roller marksand paper deformation that can occur in highspeed feeding.

The duplex paper feed mechanism of model A112(right) uses a combination of air knife and FRRfeed mechanisms. The air knife directs jets of airat the bottom of the paper stack to separate thesheets of paper. A vacuum fan holds the bottomsheet against the transport belt. The separationroller allows only the bottom sheet to feed.

airknife.tif



Paper Cassette

A paper cassette is a removable paper tray. Acassette is taken out of the machine to load paperand then reinserted in a cassette holder orcassette entrance.

Paper Lift MechanismCassettes all have a moveable bottom plate onwhich the paper rests. The bottom plate must beraised to place the paper in position to be fed.Generally, this is accomplished by raising acassette arm under the bottom plate. (Refer to thefollowing examples.)

cassett1.tif

cassett2.tif



Example 1: Model A111

This is an example of the cassette arm beingraised by a gear.

When inserting the cassette [A] into the copier,the cassette pushes down the cassette actuatorpin [B]. The paper lift clutch unit [C] moves downand then the paper lift gear [D] engages with thesector gear [E] causing the cassette arm [H] toraise the cassette bottom plate.

Simultaneously, the paper size actuator [F]engages with and actuates the paper size switch[G].

The paper lift gear turns the sector gear and thebottom plate raises until the top sheet pushes upthe paper lift sensor feeler [I].

Paper end feeler: [J]Paper end sensor: [K]




This is an example of the cassette arm beingraised by a spring.

When a cassette is inserted into the copier, thecurved release guides on the sides of the cassettepress against the rollers on the release levers [A]and force the release levers down. The releaselevers rotate the cassette arm shaft [B], movingthe cassette arm down and out of the way. Whenthe cassette is fully seated, the release guidesallow the release levers to move back up. Thecassette arm [C] levers up the cassette bottomplate [D] until the paper contacts the paper feedroller.

To prevent copy paper from multi-feeding orjamming, the spring [E] pressure is adjustable.

cassett4.tif



Paper Tray

A paper tray is a non-removable drawer or bin thatis permanently built into or attached to themachine. The capacity of paper trays variesconsiderably; smaller trays typically hold 250 to500 sheets of paper, but large capacity trays holda paper stock of 1000 or more sheets.

Paper Lift MechanismSmaller paper trays resemble paper cassettes andhave similar paper lift mechanisms employingsprings or a bottom plate lift arm.

However, large capacity trays have morecomplicated mechanisms to raise the bottom plateand place the paper in position to be fed.Generally, this is accomplished using a wire- orbelt-lift mechanism. (Refer to the followingexamples.)

500_sheet_tray.tif

1700_sheet_tray.tif



Example 1: Model A609 (belt lift)

The bottom plate [A] of the LCT is raised and lowered by the LCT motor [B] and the drive belts [C].When the main switch is on and the LCT cover is closed, the pick-up solenoid [D] activates and theLCT motor [B] rotates clockwise to raise the bottom plate until the top sheet pushes up the pick-uproller [E]. When the lift sensor [F] is de-actuated, the copier CPU de-activates the LCT motor [B] andthe pick-up solenoid [D].

a609d502.wmf

[D]

[E]

[F]

a609d501.wmf

[B]

[C]

[A]

[C]



Example 2: Model A171 (wire lift)

Drive from a reversible motor [A] is transmitted through aworm gear [B] to the drive pulley [C] shaft. The tray wireshave metal beads on them. These beads are inserted inthe slots at the ends of the tray support bracket [D] of thebottom plate; so, when the wire pulley turns(counterclockwise rear view), the beads on the wires drivethe tray support bracket and the tray moves upward. Thetray goes up until the top sheet pushing up the pick-uproller [E] actuates the upper limit sensor [F]. To lower thetray, the pulley turns clockwise until the lower limit sensor[G] is actuated by the of the bottom plate [H] actuator.

a171d620.pcx

[F]

E]

a171d629.pcx

[G]

[H]

a171d628.pcx

[B]

[C]

[D][A]



By-pass Feed Tray

Most copiers and multifunction machinesincorporate a fold-out by-pass feed table. By-passfeed is useful for casual copying on odd papersizes. Also, on most machines, the by-pass feedtray provides a straight paper path that is suitablefor stiff feed stock such as post cards or OHPtransparencies.

Example: A195

The by-pass feed table switch [A] detects whenthe by-pass feed table is opened. Then the CPUturns on the by-pass feed indicator on theoperation panel.

The by-pass feed table uses an FRR feed system,using the same rollers as the LCT, and one of thesolenoids. Only the by-pass pick-up solenoid [B] isused, because the pick-up roller does not have todrop so far as it does when feeding from the LCT.

The user can put up to 40 sheets of paper on theby-pass feed table. Note that the paper can bepushed right into the machine, causing jams. The

[C]

a195d602.wmf

[A]

a195d569.wmf



user must stop pushing the paper in when the by-pass feed indicator goes out.

When the Start key is pressed, the by-pass feedclutch [C] and the pick-up solenoid turn on to feedthe top sheet of paper.

When there is no paper on the by-pass feed table,the paper end feeler [D] drops into the cutout inthe lower guide plate and the by-pass feed paperend sensor [E] is deactivated.

[B]

a195d604.wmf[D]

[E][C]



Paper Roll

Wide format copiers and machines that use athermal printing process commonly feed paperfrom a roll.

The illustration to the right shows the maincomponents of a roll feeding system—the paperfeed rollers [A], the paper roll [B], the cutter unit[C], and the paper leading edge sensor [D].

sr740-4.pcx



Example: A175

This machine has two standard roll feed units (1st[A] and 2nd [B]), one manual feed unit, and oneoptional roll feed unit (3rd [C]). The cutter unit [D]uses a sliding rotary cutting blade.

When the main switch is turned on or when rollpaper is replenished, the roll feed motor rotatesand the leading edge of the roll paper is fed untilthe roll lead edge sensor [E] is activated. Then,the leading edge of the roll paper is returned tothe paper feed start position (120 mm before thecutter unit).

When the original lead edge sensor detects theleading edge of the original, the roll feed motorand the roll feed clutch turn on, and paper feedstarts

a174d507.wmf

[B]

[D]

[E]

[A]

[C]



Cutter OperationThe illustration to the right shows the type of rollpaper cutter used by wide format copiers.

This cutter unit uses a sliding rotary cutting blade[A] that is pulled past a fixed blade by a drive wire.The rotary cutting blade allows the cutter unit tocut paper in both directions. There are homeposition switches [B] at both ends of the cutterunit. The cutter motor turns off, stopping thecutting action, when the rotary cutting blade knobplate [C] turns off one of these switches.

Some smaller products such as thermal faxmachines and white-board printers use similarcutters to cut roll thermal paper.

sr740-7.pcx



Paper Size Detection

For many copy processes, operation timing depends on paper size. Machines can detect paper sizein a number of different ways. Here are some common ones.NOTE: Sometimes there isn’t a paper size detection mechanism. For example, for the 3rd tray of

model A171, the paper size must be input using the SP mode.

Switch CombinationThe illustration to the right shows a paper sizedetection mechanism commonly used withcassettes and smaller paper trays.

A block of five microswitches [A] detects the papersize. The switches are actuated by an actuatorplate [B] on the cassette or tray. (Generally, suchan actuator is set manually.) Each paper size hasits own unique switch combination and the CPUdetermines the paper size by the combination. a229d614.wmf

[B]

[A]



Paper Size DialSome paper trays use a dial to change paper size.

The illustration to the right shows a case wherethe paper dial changes both the guide postsposition and paper size. When the paper size dial[A] is rotated, the cam groove [B] moves the sizelever [C], which repositions the guide posts [D].When the dial reaches a standard paper size, oneof the actuator plates [E] enters the paper sizesensor array [F]. The combination of sensorsactivated tells the CPU the paper size.

Paper Size Detection Table

SensorPaper Size

1 2 3 4 5B4 0 0 0 1 1

A4 Sideways 0 0 1 0 0A4 Lengthwise 0 0 1 0 1B5 Sideways 0 0 1 1 0

B5 Lengthwise 0 0 1 1 111" x 81/2” 1 0 0 0 181/2" x 11" 1 0 1 1 081/2" x 14" 1 0 1 0 0

rt17dial.pcx



This illustration shows a paper size dial that isused to change only the paper size setting for theCPU. The paper side fences are set manually.

There are four microswitches [A] on the front rightplate of the machine that detect paper size. Theswitches are actuated by a paper size actuator [B]on the inside of the paper size dial, which is on thefront right of the tray. Each paper size has its ownunique combination of notches. To determinepaper size, the CPU reads which microswitchesthe actuator has switched off.

g020d025.wmf

[B]

[A]



Side Fence DetectionMany trays have sensors to detect the side fenceposition.

In the upper example, the paper size detectionsensors [A] are mounted under the paper traybottom plate. When the rear side fence [B] isinserted into one of the paper size positions, itenters a photointerrupter. The signal from thissensor informs the CPU which size paper is in thetray.

The lower example is a tray that can be easilyadjusted for different paper sizes by moving theguide post brackets [C] and the end post [D]. Theguide post brackets and end post have actuatorplates mounted on their bottoms. These platesactivate sensors [E] (photointerrupters) mountedunder the bottom plate. The CPU determines thepaper size by reading the combination of sensorsactivated.

a171d539.pcx

[B]

[A]

a171d621.pcx

[C]

[E]

[E]

[D]



By-pass Size DetectionBy-pass paper size detection has to be able tohandle various paper sizes and orientations.

Many machines measure paper width with a slideswitch [A] located inside the by-pass tray [B]. Theside fence is connected to a terminal plate [C].When the side fences are moved to match thepaper width, the terminal plate slides along thewiring patterns on the detection board. Thepatterns for each paper width on the detectionboard are unique. Therefore, the machinedetermines the width of the paper placed in theby-pass tray by the signal output from the board.

However, the by-pass tray cannot determine thepaper length. A4 paper set sideways isdetermined to be A3 paper. Generally, theregistration sensor or paper feed sensormeasures the length of the paper (using pulsecount) so the various copy processes cut off at theproper time.

[B]

[A]

[C]

g020d030.wmf

[C][A]

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Paper End Detection

No matter what the paper source—cassette, tray, by-pass, or roll—the machine has to detect whenpaper runs out. This can be done in many ways. Here we will look at some of the most common.

Paper End Feeler MethodCassettes generally detect the paper endcondition through the use of a feeler which dropsthrough the cassette’s bottom plate when paperruns out. The illustration shows a typicalmechanism.

When paper is loaded in the cassette, the paperholds up the feeler [A] and the actuator stays outof the slot of the paper end sensor [B] (photo-interrupter). When the paper runs out, the feelerdrops through a cut-out [C] in the bottom plateand the actuator enters the paper end sensor,thus notifying the CPU that paper has run out.

Trays also often use paper end feelers.

It is necessary to have some mechanism to movethe feeler out of the cut-out in the bottom platewhen the tray or cassette is pulled out.

[B]

[C]

[A]

endfeeler1.wmf


Handling Paper

The illustration to the right shows a typical paperend detection mechanism for a small paper tray.

When the paper tray runs out of paper, the paperend feeler [A] drops into the cutout [B] in the traybottom plate, and the paper end actuator activatesthe paper end sensor [C].

The paper end actuator is in contact with a lever[D]. When the tray is drawn out, the lever turns asshown by the arrow and pushes up the actuator.As a result, the feeler rotates upwards. Thismechanism prevents the feeler from gettingdamaged by the paper tray body.

Some trays have the paper end detectionmechanism under the tray bottom plate. To theright is one possible configuration. (paper endfeeler: [E], paper end sensor: [F])

[B]

[A

9 August 2003

Paper Feed

[C]

[D]

endfeeler2.wmf

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Page 41


Roll end detectionRoll paper end is detected by a reflectivephotosensor. When paper [A] is present, lightreflects back to the sensor [B]. When paper runsout the black core [C] doesn’t reflect light andpaper end is detected.

rollendsensor.wmf

[B]

[C][A]


Handling Paper Registration

Registration

Overview

There is often some slippage during paper feed. As a result, paper cannot be transported directly tothe image transfer or printing position, because the image position on the paper would not be stable.After paper feed starts, its transport timing requires adjustment to match it with the imaging processtiming. This alignment is called “image registration” or just “registration”. Generally the registrationprocess also removes any skew that the paper may have acquired during paper feed.



Registration Using A Stopper

Some machines use a stopper to delay the paperat the registration rollers. It allows a simplifieddrive mechanism where the registration rollers arenot stopped during feeding. This method is usedmainly with low speed machines.

Example: Model A226/A227

The registration rollers [A] always rotate while themain motor rotates. Relay rollers (not shown)transport the paper to the registration rollers.

There is a paper stopper [B] between the relayrollers and the registration rollers. After theleading edge of the paper reaches the stopper,the paper buckles slightly to remove skew. Then,2.9 seconds after the paper feed clutch is turnedon, the registration solenoid [C] is energized tomove the stopper down, releasing the paper. Thissynchronizes the paper feeding with the image onthe drum. After 0.6 seconds, the registrationsolenoid is de-energized.

[A]

[B][C]

a227d517.wmf



Registration Using Rollers

Most copiers and printers use registration rollersto match the paper timing to the image andremove skew.

Example: Model G020

The registration sensor [A] is positioned justbefore the registration rollers. When the paperleading edge activates the registration sensor, theregistration clutch [B] turns off and the registrationrollers [C]s stop turning. However, the relay clutchstays on for a bit longer. This delay allows time forthe paper to press against the registration rollersand buckle slightly to correct skew. Theregistration clutch energizes and the relay clutchre-energizes at the proper time to align the paperwith the image on the drum. The registration andrelay rollers feed the paper to the image transfersection.

G020registration.wmf

[C][B]

[A]


Handling Paper Paper Transport

Paper Transport

Roller TransportThe illustration to the right shows a typical verticaltransport mechanism that is used in severalmodels.

Three sets of vertical transport rollers [A], drivenby the paper feed motor, and their opposing idlerollers [B] are mounted in vertical guide plates [C].They transport the paper from each feed unit tothe registration rollers.

The vertical transport guides can be opened toaccess jammed paper in the vertical transportarea.

vertrans.wmf

[B]

[C] [A]


Handling Paper Paper Transport

Belt + Vacuum Transport

Many photocopiers use a combination of belts andvacuum fans to transport paper from the drum tothe fusing unit. The vacuum holds the paper firmlyagainst the transport belts. This method has theadvantage of holding the paper secure to preventvibrations or slippage that might disturb the as yetunfused toner image.

The number of transport belts and fans variesdepending on the product. A single vacuum fanwith multiple transport belts is common. Theillustration to the right (from model A166) shows amechanism employing two belts and two vacuumfans.

belt_vac.wmf


Handling Paper Duplex

Duplex

Duplexing mechanisms can take many forms. However, they have the following things in common.

• They all have some way of sending copies or prints to the duplex mechanism. This is usuallyaccomplished by a “junction gate”, which redirects the paper as it exits from the fusing unit.

• There is a mechanism that turns the paper over (reverses it) so that it is ready to receive an imageon the reverse side. This can occur before the paper enters the duplex tray or after it exits theduplex tray.

Duplexing systems in most machines also have the following mechanisms.

• There is a tray to hold the sheets of paper to be duplexed. Usually, it is simply "called the “duplextray”.

• There is a mechanism, usually called a jogger, to align the sheets of paper in the duplex tray.

• There is a paper feed mechanism employing one of the standard paper separation techniques.

Duplex Tray

A duplex tray holds sheets for multi-copy duplexing. The following example illustrates the basicoperation of a commonly used duplex tray system.



Example: Model A195

The junction gate [A] rotates up 1.1 seconds afterthe registration clutch turns on to direct copies tothe duplex tray. Shortly after the fusing exit sensordetects the leading edge of the paper, theentrance rollers [B] and duplex feed roller [C] startto rotate. At the same time, the duplex bottomplate [D] lowers.

The copy feeds over the duplex feed roller andinto the tray, thus reversing the copy. The joggerfences [E] and end fence [F] move inward tosquare the copy stack, then they move back 10.5mm from the paper stack. After the final copy isdelivered to the stack area, the jogger and endfences remain against the paper stack.

Soon after the final copy is squared, the duplexbottom plate lifts to the paper feed position andthe duplex feed roller starts rotatingcounterclockwise to feed the top copy to the relayrollers [G]. The second side is then copied withthe copy following the paper tray feed stationpaper path.

a195d577.wmf

a195d578.wmf

[B][C]

[D][E][F]

[G]

[A]



Duplex Stacking (Jogger)

When sheets of paper enter a duplex tray theytend to become misaligned. A “jogger” aligns thesheets of paper before printing on the reverse sidestarts.


Two motors drive the fences—the side-fencejogger motor [A], and the end-fence jogger motor[B]. Using two motors for the side and end fencesallows the duplex tray to handle all paper sizesfrom A3/11" x 17" to A5/ 8½" x 5½" sideways.

There are two home position sensors. One is forthe jogger fences [C], and the other is for the endfence [D]. When the main switch turns on, the sidefence jogger motor and the end fence joggermotor rotate to place the jogger fences and theend fence at their home positions.

There are two end fences. One [E] is for A3/11 x17" size paper. The other [F] is for sizes smallerthan B4. They are included as a unit. When A3/11x 17" size paper is in the duplex tray, the endfence unit moves to the left (as seen from the

A195jog1.wmf

[C][A]

A195jog2.wmf

[B]

[D]

[F]

[G]



operation side of the machine) and the B4 endfence rotates down as it is pressed against theend fence stopper [G].

When the registration clutch turns on, the sidefences move 10.5 mm, and the end fence moves8.7 mm away from the selected paper size. Then,when the copy paper is delivered to the duplextray, the jogger fences move inward to square thepaper after the duplex turn sensor detects thetrailing edge of the copy paper. Shortly after this,the jogger fences move back to their previouspositions. After the last copy of the first side copyrun enters the duplex tray, the jogger fencesremain against the paper stack.

10.5mm

8.7mm

10.5mm

A195jog3.wmf




As in the previous example, model A171 uses twomotors in the duplexing mechanism. The joggerfence drive motor [A] positions the side fences [B]and the end fence drive motor [C] positions theend fence [D].

During the copy cycle, the side fences wait 10 mmaway from the selected paper size position. Aftera sheet enters the duplex tray, the jogger fencedrive motor moves the jogger fences in to alignthe paper stack and then moves them back out tothe 10 mm position.

The end fence, however, does not have a joggingfunction. Instead, this model uses a positioningroller [E] to move the paper to the feed position.

A pressure plate [F] prevents the paper stack frommoving while the sheet enters the duplex tray.After it is released, the positioning roller movesdown and drives the sheet to the feed position.

(Pressure plate solenoid: [G], positioning rollersolenoid: [H])

A171D546.wmf

[C]

[D]

[A][B]

A171D545.wmf

[E][F]

[G]

[H]



Interleave Duplexing

OverviewSome digital machines have a lot of RAM and a large capacity hard disk that can store many pages.This allows a different method of duplexing called “interleave duplexing”, in which sheets are notstacked. Instead, in interleave duplexing, sheets are continuously fed through the machine and thecorrect image is selected from memory or disk depending on which sheet and side is in the imagingsection.

This type of mechanism allows more than one page to be processed at once, and it increases theproductivity of duplex imaging, especially when making multiple duplex copies. Also, in the case ofmaking copies from paper originals, it decreases the cycling of and the wear on originals.

Example: Model A229

For paper lengths up to A4/Letter lengthwise, the top duplex speed is possible, with the duplex unitprocessing three sheets of copy paper at the same time.

For paper longer than this, the duplex tray can still process two sheets of copy paper at once.

In case of single-set duplex copy job, the duplexing processes only one sheet of copy paper at atime.



Up to A4/Letter lengthwise

The duplex unit can process three sheets at of copy paper at once.

Example: A 14-page copy. The large numbers in the illustration show the order of pages. The smallnumbers in circles show the order of sheets of copy paper (if shaded, this indicates the second side).

1410138116

3 421 ⇒ ⇒ 5 ⇒ ⇒ 7 ⇒ ⇒ 91 2 3 1 4 2 5

12⇒ ⇒ ⇒ ⇒ ⇒ ⇒3 6 4 7 5 6 7

A229D550.WMF



1. The first 3 sheets are fed and printed.1) 1st sheet printed (1st page)2) 2nd sheet printed (3rd page)3) 3rd sheet printed (5th page)

2. The first 3 sheets go into the duplex unit.3. The 4th sheet is fed in.

A229D545.WMF

A229D546.WMF



4. The back of the 1st sheet is printed (2nd page).5. The 4th sheet is printed (7th page).

6. The 1st sheet is fed out (1st and 2nd pages printed).7. The 4th sheet is directed to the duplex unit.8. The back of the 2nd sheet is printed (4th page).9. The 5th sheet is fed.

A229D547.WMF

A229D548.WMF



10. The 2nd sheet is fed out (3rd and 4th pages printed).11. The 5th sheet is printed (9th page) and directed to the

duplex unit.12. The back of the 3rd sheet (6th page) is printed.13. The 6th sheet is fed and printed (11th page).

14. The 3rd sheet (5th and 6th pages) is fed out15. The back of the 4th sheet (8th page) is printed.16. The 7th sheet is fed and printed (13th page).

17. The back of the 5th sheet (10th page) is printed.

A229D549.WMF

A229D583.WMF



18. The 4th and 5th sheets are fed out (pages 7 to 10).19. The back of the 6th (12th page) and 7th (14th page)

sheets are printed.

20. The 6th and 7th sheets are fed out (pages 11 to 14).

When copying on A3 or 11” x 17” paper, the process is similar, but only two sheets at a time can beprocessed. For details, refer to the service manual for model A229.

For another example of interleave duplexing, refer to the service manual of the A687 duplex unit.

A229D584.WMF


Handling Paper Misfeed Detection

Misfeed Detection

Office machines that print images on paper (copiers, fax, laser printers, etc.) have to detect papermisfeeds and jams and take appropriate action. One or more sensors placed along the paper pathaccomplish misfeed detection. Typically, photointerrupters with feeler actuators are used for misfeeddetection because they are unaffected by the reflectivity or transparency of the feed stock.

The number of misfeed detectors used depends on the length and complexity of the paper path. Thefollowing timing chart, from model A226/A227, is an example of misfeed check timing in a low-endmachine.

Start Key

Main Motor

Paper FeedClutch

RegistrationSensor

RegistrationSolenoid

Exit Sensor

Paper LengthDetection

0

1.2

6.7

6.712.4

2.9 3.5

OFF Check

ON Check

ON Check

PE

(second)

A227d519.wmf



This machine uses the registration sensor and the exit sensor to detect misfeeds. The CPU checkseach sensor twice—first it does an ON check to confirm paper arrival and then it performs an OFFcheck to confirm that the paper has passed the sensor.

Larger machines have more complex paper paths and transport paper at higher speeds. Theillustration on the following page shows the misfeed sensors along the paper path of model A112.

Model A112 uses 20 sensors to detect misfeeds. This is a high-speed machine (101 cpm) and,therefore, paper transport timing is much more critical than in a low-speed machine. For that reasonthe CPU does not just perform simple ON and OFF checks at points during the copy cycle. Instead,for each sensor, it monitors two critical periods. For both the ON and OFF checks, the sensor maychange state within a period that is -93.6 ms and +117 ms from the standard check timing.

f5jam1.pcx



f5jam1.pcx


Handling Paper Handling Originals

Handling Originals

Most office machines that scan or copy paper documents are equipped with a document feeder.These feeders are variously called automatic document feeders (ADF), auto reversing documentfeeders (ARDF), or automatic document handlers (ADH); however, we will refer to them all as“document feeders” in this section. While document feeders vary in mechanical and operationaldetails, they generally have to do the following basic tasks:

• Feed documents one at a timefrom a stack of documents

• Detect the document size

• Transport the documents to thescan position

• Invert the documents (ifreverse side scanning isnecessary)

• Feed out the documents (original exit)

In this section, we will look at typical ways that these tasks are accomplished, and at specificexamples of each.

A typical document feeder



Document Feed

Document feed is a special case of paper feed, which was covered earlier in this chapter. Mostdocument feeders use one of three paper-feed methods. These are:

• The separation belt system

• The separation tab system

• A modified feed and reverse roller systemusing a feed belt rather than a feed roller

The following pages briefly cover the separation beltand separation tab systems, and cover more indepth the FRR with feed belt system.

Separation BeltThe separation belt system is covered earlier inthis chapter. This system is also called the “frictionbelt” system. This system is mainly used indocument feeders that feed sheets from the bottomof the original stack.

The illustration to the right shows the feed system ofthe DF61/DF64. For details on the feed mechanismof this ADF, refer to the service manuals for theDF61 and DF64 (used with model A133).

[A] Separation Belt[B] Feed Roller[D] Pick-up Roller[E] Pull-out Roller[F] Registration Sensor



Separation TabThe separation tab system is covered earlier inthis chapter. This system, which is also called the“friction tab” system, is used in document feederswhen a straight paper feed path is required.

The illustration to the right shows the feed systemof the document feeder of model A084. For moredetails, refer to the ARDF section of the servicemanual for model A084.

[A] Feed Roller[B] Separation Tab[C] Pick-up Roller[D] Relay Rollers



FRR with Feed BeltSome document feeders, especially those usedwith higher throughput machines, use a version ofthe FRR (feed and reverse roller) system thatemploys a feed belt rather than a feed roller. Afeed-belt type FRR provides more contact areathan a roller type. This makes it more reliable forfeeding original documents, which can vary over awide range of types, sizes, and conditions.However, feed-belt type FRR is rarely used forprimary paper feed (where feedstock quality canbe controlled and throughput is much higher)because it is relatively expensive in terms of partsand maintenance.

Example: Model A294

The pick-up roller [A], feed belt [B], and separationroller [C] are driven by the feed-in motor [D]. Thefeed-in motor [D] and feed-in clutch [E] turn on tosupply the drive for the separation process.

Basic operation is the same as for standard FRR.When two originals are fed by the pick-up roller,the separation roller will turn opposite the feed belt

[E]

[D]

[A]

[C]

[B]

[B]

[C]



direction and the 2nd sheet will be pushed backinto the original tray. When there is only oneoriginal between the feed belt and separationroller, the separation roller will then rotate in thesame direction as the feed belt and feed theoriginal through to the platen glass. Theseparation roller contains a torque limiter so thatit can rotate in both directions.

When the leading edge of the original activatesthe entrance sensor [A], the feed-in clutch [B]turns off and the drive for the feed belt is released.The original is now fed by the transport rollers [C]to the platen glass.

At the same time, the pick-up motor starts againand the pick-up roller [D] is lifted up. When thepick-up roller HP sensor turns on, the pick-upmotor stops.

[B]

[D]

[A]

[C]



Original Size Detection

Most Ricoh made document feeders use one of two main methods to detect original size.

One method dynamically detects the original size using sensors to detect the width and length of theoriginal “on the fly” as the DF feeds it in. This method allows the user to copy a stack of mixed sizeoriginals. However, the drawback is that it may not be possible to start paper feed until after theoriginal has been fed (in auto paper size selection mode, for example).

The other method is a static detection system. It detects the original size prior to feeding. Generallythis is done by sensing the position of the side fence to determine the original width and by sensingthe original length with reflective photosensors on the original tray. Naturally, only the largest sheetwill be detected by this method; so, mixing different size originals isn’t recommended.

This following pages look at an example of each method.

Some document feeders, especially those used with low copy rate machines, do not measureoriginal size. The DF40 is an example. It is the user’s responsibility to ensure that the paper sizematches the original size on such machines.



Dynamic Original Size DetectionThe original size is sensed “on the fly” as it feedsin.

Example: Model A294

Model A294 (Bellini) detects the original size bycombining the readings of the original lengthsensor [A] and three original width sensors [B]while the original feeds in.

The original length sensor generates pulses as aslotted disk [C] rotates. The slotted disk engageswith the shaft of the driven transport rollers, so itturns as the paper moves past. The CPU thencounts these pulses, starting when the leadingedge of the original turns on the registrationsensor [D]. Pulse counting continues until thetrailing edge of the original passes the entrancesensor [E].

The CPU detects original width by using the threeoriginal width sensors. The three small circlesshown in the diagram to the right indicate thepositions of these sensors.

[C]

[E]

[A]

[D]

[B]



Static Original Size DetectionThe original size is sensed prior to feeding whilethe originals are on the document feed table.

Example: DF68

DF68 has one sensor [A] to detect the originalwidth and two sensors [B] to detect the originallength. The DF detects the original size throughthe combination of inputs from those sensors.

The original width sensor [A] is actually a slideswitch with four possible outputs (P1 to P4). Theoutput depends on the position of the slidingcontact on the original rear fence.

The original length sensors [B] are two reflectivephotosensors.

When using an original of a non-standard size, theuser needs to input the original length at theoperation panel.

[B]

[A]



Original Transport

This section deals with transporting the document after document feed.

Original Transport falls into two major classes based on the document scanning method. One type ofdocument feeder transports the document past fixed optics. In such document feeders the documentnever stops; transport and feed-out occur as one continuous process. This will be the firstmechanism examined in this section.

The second type of document feeder positions the document on an exposure glass, where it isscanned by moving optics. Such document feeders usually have several other transport functions.We will look at belt transport, skew correction, document inversion, and feed-out as separate originaltransport processes in such machines.

Transport Past Fixed OpticsWhen the optics are fixed, scanning is done by moving the document past the reading mechanism ata constant rate. This is the basic way that fax machines work, but it is also used in somemultifunction machines. The basic requirements are that the paper transport speed and the distancefrom the document to the exposure glass both remain constant. Such document feeders are simplein design and operation. The major drawback is that they cannot easily be designed for duplexing.



Example: DF68

When the leading edge of the original reaches theregistration sensor [A], the DF transport motorsturn off. At the proper registration timing, the DFtransport motors turn on again. The original is fedpast the DF exposure glass [B], where it isscanned. The original is fed through to the 2ndtransport roller [C] and fed out by the exit rollers[D].

The DF transport motor speed, while feeding theoriginal to the registration sensor, is constant.However, when the motor turns on again to feedthe original to the exposure glass, the speeddepends on the selected reproduction ratio. At100%, it is 90 mm/s. [A]

[D]

[C][B]



Transport BeltMost document feeders use a roller driven belt to position documents on the exposure glass.

Example: Model A294

The transport belt [A] is driven by the transportbelt motor [B]. The transport belt motor startswhen the copier sends an original feed-in signal.

Inside the transport belt are six pressure rollerswhich maintain the correct pressure between thebelt and original. The pressure roller [C] closest tothe left original scale is made of rubber for thestronger pressure needed for thick originals. Theother rollers are sponge rollers.

Normally, originals are manually placed at the leftrear corner, so an original [D] fed from the DFmust also be at this position. But if the original isfed along the rear scale [E], original skew, jam, orwrinkling may occur.

To prevent such problems, the original transferposition is set to 3.5 mm away from the rear scaleas shown. The 3.5 mm gap is compensated for bychanging the starting position of the main scan.

[C]

[B]

[A]

[E] [D



Skew CorrectionSkew correction compensates for any misalignment (original skew) that occurs when the original istransported to the exposure glass by the document feeder. The original is pushed against a scale,after transport to the exposure glass, to align it properly.

Example: Model A294

The transport belt motor remainsenergized to carry the original about 7mm past the left scale [A] (see themiddle drawing). Then the motor stopsand reverses to feed the original backagainst the left scale (see the bottomdrawing). This forces the original to hitthe left scale, which aligns the trailingedge to minimize original skew on theexposure glass.

After a two-sided original has beeninverted to copy the 2nd side, it is fedin from the inverter against the leftscale (see the bottom drawing; the toptwo drawings do not apply in this mode).

If a thin original mode is available (and is selected), skew correction does not occur. This preventsdamage to the thin originals.

[A]



Original InversionDocument feeders must invert (or turn over) documents to copy the reverse side or—with somedesigns—to return documents to their original order. Document feeders have various mechanismsfor inverting originals. Most involve routing the document around a roller (or rollers) using solenoid-actuated gates. The example shown below is typical.

Example: Model A294When the DF receives the original invert signalfrom the copier, the transport belt motor, feed-outmotor, exit gate solenoid [A], and inverter gatesolenoid [B] turn on and the original is fed back tothe exposure glass through the inverter roller [C],exit gate [D], inverter guide roller [E], inverter gate[F], and inverter roller.The transport belt motor turns in reverse shortlyafter the leading edge of the original turns on theinverter sensor [G], and feeds the original to theleft scale.

[C]

[A]

[B]

[F]

[G]

[D]

[E]



Original ExitDocument feeders switch gates within the exit/inverter section to direct documents to the exit tray.

Most document feeders have only one exit tray, which necessitates inverting the documents twice tokeep them in proper order. However, the example below has two exit trays one for duplex mode andthe other for normal mode; so, throughput can remain high with only a single inversion required induplex mode.

Example: Model A294

Single-sided Original Mode

The exit gate solenoid [A] remains off and the originalis fed out to the right exit tray. The transport beltmotor turns off after the exit sensor [B] turns off.To stack the originals neatly on the exit tray, the feed-out motor speed is reduced about 30 mm before thetrailing edge of the original turns off the exit sensor.

[B]

[A]



Double-sided Original Mode

The exit gate solenoid [A] turns on and the invertergate solenoid [B] remains off, and the original isfed out to the upper tray. The transport belt motorturns off when the trailing edge of the originalpasses through the exit sensor [C].To stack the originals neatly on the upper tray, thefeed-out motor speed is reduced shortly after thetrailing edge of the original turns off the invertersensor [D].

[A]

[B]

[D]

[C]


Handling Paper Handling Finished Copies/Prints

Handling Finished Copies/Prints

Handling finished copies and prints involves sorting and stacking with various tray types (fixed,moving, and shift), as well as stapling and punching. Finished copies and prints are usually handledwith a finishing or sorting unit. All finishing and sorting units do not have the same functions, butgenerally there is some sort of stacking and sorting on all basic units with stapling and punching asadded features.

This section will discuss sorting and stacking using the various tray types, stapling and punchingprocesses, and the exiting of the finished copy or print.

Sorters and finishers can be categorized into three basic types as follows:

• Those using fixed position trays or bins. These machines move the finished copies to theappropriate bin after it exits the copier.

• Those using moving bins. These move the trays to the copier exit at the appropriate time toreceive the copy as it exits the copier.

• Those using shift trays.

The following pages cover examples of each type.



Sorting/Stacking with Fixed Trays

Machines that Sort and Stack with FixedTrays are usually medium or high speedmachines. In fixed-tray sorters, the copiesare moved to the trays after exiting thecopier by belts or rollers. Fixed trays tendtoward Analog machines rather than Digitalones.

Example: Model ST23

The general concept of the fixed tray hasthe print or copy transported individually toan exit tray (usually one of many), whichdoes not move, through a series of rollers.Transportation is usually by a vertical,diagonal [D] and/or horizontal transport unit[E] with a distribution unit [F] that containsdistribution rollers, and bin gates operatedby bin solenoids.



The Sorter MechanismExample: Model ST23

Copies exiting the copier enter the sorter. They are thendelivered to the bins in order. The jogger arm arrangesthe copies in the bins. The distribution section has thedistribution rollers [A], bin gates, and bin solenoids.

When a bin gate solenoid [B] is off, the return spring [C]holds the bin gate [D] out of the paper path, allowing thecopies to pass to the upper bin.

The appropriate bin gate solenoid turns on and opensthe bin gate. The other solenoids are off. The copies goto the bin [E] through the gate.



Sorting/Stacking with Moving TraysSorters with Moving Trays tend to be smaller and less expensive. They are used with lower-endmodels. These machines usually have one of two types of mechanisms for moving trays—wheeldrive or screw drive (sometimes called a helical wheel).

Wheel DriveThe bin drive mechanism moves the bins upand down to receive copies or prints. Thismovement is made by a wheel mechanismthat is explained in the following example.

Example: Model CS130

Basic Operation- Sort Mode –In this mode, all copies of the firstoriginal are delivered to separate bins startingfrom the top. The copies of the second originalare delivered to the same bins, but starting fromthe bottom. The copies of the third original startfrom the top and so on. At 250 milliseconds afterthe copy has gone through the paper sensor, thebin drive motor turns on to advance the bin one step.- Stack Mode –In this mode, all copies of the first original are delivered to the first bin, all copies of thesecond original are delivered to the second bin, and so on. At 250 milliseconds after the last copy of theoriginal has gone through the paper sensor, the bin drive motor turns on to advance the bin one step.



[G] Exit Roller[H] Upper Paper Guide[I] Lower Paper Guide

Bin Drive Mechanism

The bin drive mechanism moves the bins up and down to receivecopies under the direction of the copier CPU. The main components inthis mechanism are the bin drive motor [A], two transfer wheels [B,B’],the wheel switch [C], and the bins themselves.

Pins on either side of each bin are inserted into slots called bin guides[D,D’]. The bins slide up and down in the bin guides. The bins sit oneach other with the lower bin resting on the 10th bin (the 10th bin ispermanently fixed in position). The upper and lower paper guides pivotup and down depending on the height of the bin to be picked up orreleased.



Screw Drive (helical wheel drive)Screw drive provides a bin drive mechanism that is more robust than the wheel drive method and issuitable for heavier workloads.

Example: Model ST10

Basic Operation

When sort mode is selected, the bin drive motor[A] energizes to rotate the helical wheels. Thehelical wheels [B] rotate twice to move the top binto the transport roller position, then the first copyis delivered to the top bin.

After the first copy of the first original has been fedto the top bin, the bin drive motor moves the binsup one step (the helical wheels rotate once) sothat the second copy of the first original will bedelivered to the next bin. The jogger plate [C]squares the copies after each copy has been fedto a bin. After the copies of the first original havebeen delivered to each bin, the sorter staplermaintains its status (the bin drive motor does notrotate). The first copy of the second original isdelivered to the final bin that was used for the firstoriginal, then the final bin descends one step. The

[A][B]

[C]



bins descend each time a copy of the secondoriginal is delivered.

The direction of motion of the bins alternates foreach page of the original until the copy run isfinished.

Stack mode is similar to sort mode. However, thebins move upward only.

Bin Drive Mechanism

The bin drive mechanism moves the bins up anddown to receive copies.

There are four pins on each bin. Two pins fit intothe slots [A] in both the front and rear side frames;the pins slide up and down in these slots. Theother two pins fit into the slot in the helical wheels;as the helical wheels turn, these pins move upand down, and the other pins move up and downin the slots at the other end of the bin.

The bin drive motor [B] drives the helical wheelsthrough four timing belts [C]. When the motorrotates clockwise, the bins lift; when it rotatescounterclockwise, the bins lower. There is a wheelsensor actuator [D] on the front helical wheel; the

[A]

[B]

[C][D]

[A]



actuator has a slot that detects when the helicalwheel has rotated once.

When the bins are advanced, the helical wheelsrotate once for each step. As the pitch of the spiralon the helical wheel is greater when the bins areat the staple and paper exit area than when thebins are elsewhere, the amount of bin shift isgreater when the bins are at the staple and paperexit area. This leaves enough space to staple andstack the copies. Also, this reduces the totalmachine height.



Sorting/Stacking with Shift Trays

Machines with Shift trays tend toward medium-sized, middle segment to upper segment machines.Recently, most digital machines are using this type of tray. Shift trays usually have up/down andside-to-side movement. This facilitates the sorting and stacking of copies or prints. The up/downmovement allows for a large number of copies to stack in the shift tray. The side-to-side movementseparates sets of copies by alternating the position of the shift tray for each set.

Example: SR810 Finisher

Up/Down MovementThe shift tray lift motor [A] controls the vertical positionof the shift tray [B] through gears and timing belts [C].When the main switch is turned on, the tray is initializedat the upper position. The tray is moved up until stackheight sensor 1 [D] is de-actuated.As paper feeds into the tray the stack height feeler [E]raises; when it actuates stack-height sensor 2 [F] theshift tray lift motor lowers the shift tray. (Exact timingand amount of movement depends on the mode. Seethe SR810 service manual for more details.)The shift tray rises until stack height sensor 1 is de-actuated when the user takes the stack of paper fromthe shift tray.

[B]

[E][D]

[F]

[A]

[C]



Side-to-Side MovementIn sort/stack mode, the shift tray [A] moves from side to side to separate the sets of copies.

The horizontal position of the shift trayis controlled by the shift motor [B] andshift gear disk [C]. After one set ofcopies is made and delivered to theshift tray, the shift motor turns on,driving the shift gear disk and the shaft[D]. The shaft positions the end fence[E], creating the side-to-sidemovement.

When the shift gear disk has rotated180 degrees (when the shift tray isfully shifted across), the cut-out in theshift gear disk turns on the shift trayhalf-turn sensor [F] and the shift motorstops. The next set of copies is thendelivered. The motor turns on,repeating the same process andmoving the tray back to the previousposition.

[F]

[B]

[C]

[A]

[E]

[D]



Paper pre-stackingThis mechanism improves produc-tivity in staple mode.

During stapling, the copier has towait. This mechanism reduces thewait by holding the first two sheets ofa job while the previous job is stillbeing stapled. It only works duringthe second and subsequent sets of amulti-set copy job.

The pre-stack junction gate solenoid[A] turns on about 230 ms after the1st sheet of paper turns on theentrance sensor, and this directs thesheet to the pre-stack tray [B]. (This sheet cannot be fed to the stapler yet, because the first set isstill being stapled.) The pre-stack paper stopper solenoid [C] turns on about 680 ms after the 1stsheet turns on the entrance sensor. The pre-stack paper stopper [D] then stops the paper.

The pre-stack junction gate solenoid turns off 450 ms after the trailing edge of the 1st sheet passesthrough the entrance sensor, and the 2nd sheet is sent to the paper guide [E]. The pre-stack paperstopper is released about 50 ms after the 2nd sheet turns on the pre-stack stopper sensor [F], andthe two sheets of copy paper are sent to the stapler tray. All sheets after the 2nd sheet go to thestapler tray via the paper guide [E].

[F]

[E]

[A]

[B]

[D]

[C]



Stapling and Punching

Stapling and punching go through a fairly set process. Thecopies are collected in a bin, stack correction occurs sothat all of the copies are aligned properly for the punch andstaple units, and finally the stapler and/or punch moves toone of usually three positions for stapling and/or punching.After stapling/punching is complete, the document istransported to the exit tray.

Example: SR810 Finisher

Stapler Unit

The stapler motor [A] moves the stapler [B] from side toside. After the start key is pressed, the stapler moves from its home position to the stapling position.

If two-staple-position mode is selected, the stapler moves to the front stapling position first, thenmoves to the rear stapling position. However, for the next copy set, it staples in the reverse order (atthe rear side first then at the front side).

After the job is completed, the stapler moves back to its home position. This is detected by thestapler HP sensor [C].

[A]

[B]

[C]



Punch Unit

The punch unit makes 2 or 3 holes(depending on the type of punch unit) atthe trailing edge of the paper.

The punch unit is driven by the punchmotor [A]. The punch motor turns on 78ms after the trailing edge of the paperpasses through the entrance sensor [B],and makes the punch holes.

The home position is detected by thepunch HP sensor [C]. When the cut-out inthe punch shaft gear disk [D] enters thepunch HP sensor, the punch motor stops.

[A]

[D]

[C]

[B]


PPhhoottooccooppyyiinngg PPrroocceesssseessOverview

1. ScanningAn exposure lamp illuminates the original. Light reflected off the original is used to create theimage on a drum*. In analog machines, the light is reflected through a series of mirrors,eventually striking the drum directly. For multi-copy runs, the original must be scanned for eachcopy.In digital machines, the reflected light is passed to a CCD or CIS, where it is converted into ananalog data signal. This data is further converted to a digital signal, processed, and stored inmemory. To print, the data is retrieved and sent to a laser diode. For multi-copy runs, the originalis scanned only once and stored to a hard disk.* In this overview section we refer to the photoconductor as a drum just for simplicity. However, be aware that thephotoconductor is often an OPC belt rather than a drum.

OverviewChargeExposureDevelopmentTransfer and SeparationCleaningQuenchingFusing

1


Photocopying Processes Overview

2. ChargingA charge is applied to thephotoconductor drum. There are avariety of methods for this. Somemachines apply a positive charge,others apply a negative. Most use anon-contact corona wire—thoughsome use a contact, charge roller.The drum holds the charge becausethe photoconductive surface of thedrum has a high electricalresistance–unless exposed to light.

3. ExposureIn an analog machine, the lightreflected off the original is redirectedto the drum. In a digital machine, the processed data from the scanned original is retrieved frommemory or from a hard disk and transferred to the drum by one or more laser beams. In bothcases, the areas exposed to light lose some or all of their charge. This writes an electrostaticimage on the drum.

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Photocopying Processes Overview

4. DevelopmentToner is attracted to the latent image on the drum. The exact process varies depending onwhether the drum holds a positive or negative charge. Most analog machines are Write toWhite—the toner is attracted to unexposed areas on the drum. Most digital machines are Write toBlack—the toner is attracted to exposed areas.

5. TransferThe image is transferred to paper. Some machines transfer the image directly from the drum.Others use an intermediary transfer belt. Transfer belts are particularly common in colormachines. The four colors are layered onto the belt, and then the final image is transferred to thepaper in one step.

6. SeparationThe paper can be separated from the drum (or image transfer belt) electrostatically ormechanically. Charge coronas, discharge plates, pick-off pawls and sharply curved paper pathsare all used. Often a machine will combine two or more methods.

7. CleaningThe remaining toner is cleaned off the drum. Most machines use a cleaning blade to wipe off theexcess toner. Some add a cleaning brush or cleaning roller to improve efficiency.

8. QuenchingLight from a lamp neutralizes the remaining charge on the drum’s surface.


Photocopying Processes

[A]

[B]

9. FusingHeat and pressure are used to melt the toner andattach it to the page. The hot roller [A] is usuallyheated by one or more halogen lamps. Thepressure roller [B] may or may not be heated.

Charge

Overview

Charge refers to the application of a uniform electrostatic charge to a photoconductor in darkness. Atpresent, two kinds of electrostatic charge methods are widely used in Ricoh products. The mostcommon is the corona electrostatic charge method (non-contact type), which takes advantage of thecorona discharge produced when a high voltage is applied to a fine wire. The other is theelectrostatic charge roller method (contact type), which provides an electrostatic charge by applying ahigh voltage to a roller and contacting the roller to the photoconductor.

9


Photocopying Processes Charge

Corona Charge

Corotron Method—Positive charge (Se)A power pack applies several thousand volts ofelectricity to a charge wire and a corona discharge isgenerated from the charge wire. The corona dischargeionizes air particles and the positive ions concentratearound the charge casing and photoconductive surface(Selenium). The photoconductor (insulator in darkness)stops the positive ions. The positive ions induce anegative electrostatic charge in the aluminum base,retaining the electrostatic charge.

Scorotron Method—Negative charge (OPC)When several thousand volts of electricity areapplied to a charge wire [A], a corona discharge isgenerated from the charge wire. The coronadischarge ionizes air particles and the negativeions concentrate around the charge casing [B] andgrid [C]. The negative ions adhere to the photo-conductor [D] (insulator in the darkness), causingpositive electrostatic charge in the aluminum base[E], retaining the electrostatic charge.

[A][B]

[C

[D]

[E]

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[B][C]

[A]

chrggrid.pcx

Scorotron Grid

The quantity of the current of dischargedelectricity along the wire length changes as shownby the chart on the right. As this suggests, anegative corona is less uniform than a positivecorona.

Therefore, the scorotron method uses a grid toeven out the electric potential on thephotosensitive surface.

The grid is located at +1 or +2 millimeters awayfrom the photosensitive surface, and the gridmaterial is either stainless steel or tungsten wire.

[A]: Grid

[B]: Power pack

[C]: Drum

050103.pcx

Coronaoutput

Effectof grid



Corona Charge Power PackA rated current power pack is used for corona charging. In comparison to a rated voltage powerpack, a rated current power pack provides a more stable image quality. It does this by stabilizing thetotal wire current even when the charge wire deteriorates or the wire resistance increases due tostaining caused by dust.

Uneven Charge PreventionTo prevent an uneven build-up of charge on thephotoconductor, a flow of air is supplied to theelectrostatic charge section. In the machineillustrated (model A184), the exhaust fan [A]causes a flow of air through the charge coronasection.

Generally, an ozone filter [B] is also installed inthe charge section to adsorb ozone (O3)generated by the charge corona.

[A]

[B]



Charge Roller Method

An electrostatic charge is applied to the photoconductor by applying several thousand volts ofelectricity to the drum charge roller [A]. The drum charge roller contacts the surface of the OPC drum[B] to give a negative charge

The DC power pack [C] for the electrostatic charge is a constant voltage type. This is because, incomparison to constant current power packs commonly used for coronas, the constant voltage typeis better able to supply a uniform electrostatic charge on the drum surface when using a roller.

The amount of ozone generated during drum charging is much less than the amount made by acorona wire scorotron system. Therefore, there is no need for an ozone filter

[A]

[B]

[C]

mo6.wmf



Drum Charge Roller ConstructionThe charge roller consists of a steel core,surrounded by layers of rubber and othermaterial.

Charge Roller CleaningIf the charge roller becomes dirty, uneven charge may be applied to the photoconductor. This woulddecrease drum charge efficiency and cause spots and streaks on the output image. For this reason,the charge roller must be cleaned.

The charge roller cleaning may be done periodically (see example 1) or, if space is limited, thecleaning pad may be constantly in contact with the charge roller (example 2).

Outer Layer:Hydrin,Fluorine com-pound, Silica

Inner Layer:EpichlorohydrinRubber

Steel Core



Example 1: Model A193—Contact and release

This machine has a contact and releasemechanism with which it cleans the charge rollerperiodically.

Drum charge roller cleaning is done for 2 secondsafter every copy job. After the copy job, the chargeroller contact clutch is driven another third of arotation. The pressure lever presses down more,so that the cleaning pad [A] contacts the chargeroller.

After charge roller cleaning, the clutch is driventhe final third of the rotation (until the charge rollerH.P sensor [B] is activated) to release the chargeroller from the drum. The pressure lever movesaway from the charge roller unit. Then the chargeroller unit is released from the drum by the springs[C].

A193D544.wmf

[B]

[A]

[C]

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[A]



Example 2: Model A230/A231/A232—Constant contact

Because the drum charge roller [A] always contacts the drum, it gets dirty easily. So, the cleaningpad [B] also contacts the drum charge roller all the time to clean the surface of the drum chargeroller.

The pin [C] at the rear of the cleaning pad holder rides on the cam [D] on the inside of the gear. Thiscam moves the cleaning pad from side to side as the gear turns. This movement improves cleaningefficiency.

[B]

[C][D]

[A]

A230D303.WMF


Photocopying Processes Exposure

Exposure

Overview

Exposure refers to a process where light is applied to a photoconductor to create a latent reverseimage in the form of a charge pattern on the surface of the photoconductive material. Dependingon the brightness of the image, the electric potential on the photoconducutor’s surface is attenuated;thus, forming an electrostatic latent image

Ricoh products use three main exposure methods—flash exposure, strip exposure (sometimescalled slit exposure), and laser exposure. The analog methods—flash and strip exposure—arecovered in this chapter. Strip exposure is further divided into exposure using moving optics andexposure with fixed optics. Laser exposure is covered in the Digital Processes chapter

Strip Exposure With Moving Optics

Strip exposure with moving optics scans a strong light source across a fixed original. The strip of theimage illuminated during this scanning, is continuously projected to the photoconductor by an opticalassembly (mirrors and lens).

This method makes it easy to obtain even illumination distributions and it is well suited to projectingimages onto cylindrical drums. Also, it is easy to change magnification by repositioning the opticalcomponents. However, it has speed limitations. Due to these characteristics, strip exposure is themost common exposure method used for low and medium speed models.



Example: Models A095/A096/A097

The illustration to the right shows the optics unit ofthe A095 series. This copier uses six mirrors to“fold” the optic path and thus make the optics unitsmaller and obtain a wide reproduction ratio range(50 ~ 200%). A halogen lamp [A] mounted in thescanner is the light source. The 2nd and 3rd mirrorcarrier [B] moves at half the speed of the scannerto maintain a constant optical distance betweenthe original and the lens [C] during scanning. Thelens and the 4th and 5th mirrors [D] can berepositioned to change the reproduction ratio. Atoner shield glass prevents toner and paper dustfrom leaking through the exposure slit into theoptics cavity.

stripexp.wmf

[A]

[D][B]

[C]



Scanner DriveHere we will look at a couple of examplesof scanner drive mechanisms in analogmachines.

The illustration to the right shows a typicaldrive mechanism for an analog processphotocopier. (Model A095)

A dc servomotor is used as the scannerdrive motor [A]. Scanner drive speedduring scanning depends on thereproduction ratio. For a 100% copy, thescanning speed is 330mm/s.

The scanner drive motor drives the first[B] and second scanners [C] using twoscanner drive wires via the timing belt [D]and the scanner drive shaft [E]. Thesecond scanner speed is half of the firstscanner speed. The scanner drive wire isnot directly wound around the pulley onthe scanner drive motor.

scandrv1.pcx



The second scanner drive example (model A219) shows scanner drive using belts rather than wires.

A stepper motor [A] drives the scanners. The first scanner [B], which consists of the exposure lampand the first mirror, is connected to the first scanner belt [C]. The second scanner [D], which consistsof the second and third mirrors, is connected to the second scanner belt [E]. Both the scanners movealong the guide rod [F].

A219D522.wmf[B]

[C]

[D]

[E]

[F]

[G]

[H]

[A]



There are no scanner drive wires, and only one side of the scanner is supported (by a rod and guiderail).

The pulley [G] drives both the first and second scanner belts. The 2nd scanner moves at half thespeed of the first scanner. This maintains the focal distance between the original and the lens duringscanning.

The scanner home position is detected by a home position sensor [H]. The scanner return position isdetermined by counting the scanner motor drive pulses.



Lens DriveFor a copier to make reduced or enlargedcopies, the lens must be moved to achievethe proper optical distance between the lensand the drum surface for the selectedreproduction ratio.

There are many ways this can be done. Theillustration (from model A152) shows a typicalarrangement. In this case, a stepper motor[A] changes the lens [B] position through thelens drive wire [C].

The rotation of the lens drive pulley movesthe lens back and forth in discrete steps. Thehome position of the lens is detected by thehome position sensor [D]. The main boardkeeps track of the lens position based on thenumber of pulses sent to the lens motor.

lensdrv1.pcx



Mirror PositioningTo make reduced or enlarged copies, it isn’tenough to just move the lens. To maintain focus,analog copiers must move mirrors also. For thetypical 6-mirror exposure system, the 4th/5th mirrorassembly is repositioned. (This is sometimesreferred to as “third scanner drive”; however, thatactually isn’t an accurate name because themirrors are stationary during scanning.)

The illustrations to the right show two examples. Inthe upper illustration, a stepper motor [A] changesthe 4th/5th mirror assembly position through a rackand pinion drive system [B].

The lower illustration shows a system where themirror assembly is repositioned using a drive belt[C].

A171D567.pcx

[C]

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[B]

[A]



Strip Exposure With Fixed Optics

Strip exposure with fixed optics is a systemwhere the original moves and the optics andlight source are fixed. A strip of the originalimage is illuminated as it moves past the optics,and the optics continuously project this stripimage to the photoconductor. While severaltypes of optics could be used for this system,Ricoh uses a SELFOC fiber optic array. Thefiber optic array has the advantage of being verycompact. For that reason it is used mostly inlarge format copiers, where lens and mirroroptics are impractical, and in small, low speedpersonal copiers, where compact size isimportant.

Original document

SELFOC fiber optic array

Exposure image

ips138.wmf



Example: Model A174 (Whale)

The illustration to the right shows the exposuremechanism of the model A174.

Light from the exposure lamp [A] reflects off theoriginal and through the fiber optics [B] to theOPC drum [C]. During exposure, the originalmoves across the exposure glass at the samespeed as the drum’s peripheral velocity.

The platen roller [D] presses the original [E] flatagainst the exposure glass [F] just above thefiber optic array. This ensures that the image isproperly focused. (The original must be within0.2 mm of the exposure glass surface.)

The exposure lamp is a fluorescent lamp.

a174d505.wmf

[A]

[B]

[C]

[D][E]

[F]



Flash Exposure

Flash exposure is an overall exposure method, whichprojects the document image onto the photoconductor,by exposing the entire document surface at once. Asthis method does not require a scanning mechanism, itenables high speed copying. However, it requires thephotoconductor’s surface to be flat and it requires anoptics cavity that is quite large compared to standardscanner optics.

Example: Models A112/A201 (Big Bird)

The illustration to the right shows the exposuremechanism of the FT9101/9105. A xenon flash lamp[A] illuminates the entire document in a single flash oflight. The flash is of such short duration (170 ms) thatthe opc belt [B], which moves at 430 mm/s, does nothave to stop during exposure.

Reflectors [C] provide even light intensity to theoriginal. Even though mirrors [D] are used to ‘fold’ thelight path, most of the interior of the main body of thecopier is taken up by the optics cavity. IPS165.wmf

[A]

[C]

[B]

[D]



Exposure Lamp Control

Fluorescent Lamp

Feedback Control System

Light from a fluorescent lamp tends tofluctuate. For this reason, exposure lampintensity must be stabilized during the copycycle to get a constant latent image on thedrum. To accomplish this the actual lightoutput by the lamp is fed back to a controlcircuit.

The illustration to the right (from modelA171) shows a typical control system. Themain PCB [A] monitors the light intensitythrough a fiber optics cable [B]. based onthis input, a lamp power signal (pulse widthmodulated signal) is sent to the fluorescentlamp regulator [C].

A171D572.pcx

[B]

[C]

[A]



Fluorescent Lamp Regulator

The fluorescent lamp regulator (also called“FL stabilizer”) converts the power input to astable, high-frequency ac output to thefluorescent lamp. A fluorescent lampoperates more efficiently with highfrequency power input.

The percentage of the time that the lampreceives power—the duty cycle—iscontrolled by a pulse width modulatedcontrol signal.

In the illustration to the right (from modelA163), the lamp regulator [A] receives 24volts dc at CN401-1 from the PSU [B]. Thecontrol signal, which is a pulse widthmodulated (PWM) signal, is received atCN401-4. The PWM signal has a period (T)of 1 millisecond and a duty ratio of 15% to100%.

FL_regulator.pcx



explamp1.pcx

explamp2.pcx

Halogen LampThe illustration to the right (from modelA110) shows a typical control circuit fora halogen lamp used for exposure.

The main board sends lamp triggerpulses to the ac drive board fromCN122-7. PC401 activates TRC401,which provides ac power to the expo-sure lamp, at the trailing edge of eachtrigger pulse.

The voltage applied to the exposurelamp is also provided to the feedbackcircuit. The feedback circuit stepsdown (TR401), rectifies (DB401), andsmoothes (zener diodes and capacitors) the lamp voltage. TheCPU monitors the lowest point of the smoothed wave (feedbacksignal), which is directly proportional to the actual lamp voltage.

The CPU changes the timing of the trigger pulses in response tothe feedback voltage. If the lamp voltage is too low, the CPUsends the trigger pulses earlier so that more ac power is appliedto the exposure lamp. This feedback control is performedinstantly; so, the lamp voltage is always stable even underfluctuating ac power conditions.


Photocopying Processes Development

DevelopmentThis section covers standard systems for latent image development that are commonly used in Ricohproducts. These development systems are divided into the dual-component development methodand the mono-component development method.

Dual-Component Development (Magnetic Brush)

OverviewThe two-component development process usesdeveloper made of mixed toner [A] and carrier [B]. Thesetwo components rub against each other in the develop-ment unit and take on opposite charges. When aselenium photoconductor (drum) [C] is used, the tonertakes a negative charge and the carrier takes a positivecharge.

The carrier consists of resin-coated metallic particles, andthey align with magnetic lines of force from magnets [D]inside the development roller, [E] forming a magneticbrush. The rotating drum contacts the magnetic brush,and the charged latent image areas of the drum attractthe oppositely charged toner particles.

[A] [E]

[D][C]

[B]

magbrush.pcx



Features

Advantages

• Achieves high speed development• Allows relatively wide scope in terms of accuracy

Disadvantages

• The development section is complex and large• Deterioration of developer over time (difficult to achieve maintenance free operations)• Requires toner concentration control

Developer Composition

Carrier

Carrier consists of roughly spherical metallic particles ranging in size from 50 to 200 µm. Theparticles have a resin coating with specific characteristics which determine the polarity and strengthof the carrier’s triboelectric charge.

Toner

Several weight percent of toner (weight ratio) is mixed with the carrier. Toner particles have adiameter of 5 to 20 µm. Toner particles are made of a thermosetting carbon black resin in which anelectrostatic charge agent is mixed. The triboelectric characteristics ensure that the toner alwaystakes on a charge that is opposite to the carrier.




Model A153 has a typical dual componentdevelopment unit. The parts shown in theillustrations are standard to most dual componentsystems.

When main motor rotation is transmitted to thedevelopment unit, the paddle roller [A],development roller [B], auger [C], and agitator [D]start turning. The paddle roller picks up developerin its paddles and transports it to the developmentroller. Internal permanent magnets in thedevelopment roller attract the developer (thecarrier particles are about 70 micrometers indiameter) to the development roller sleeve.

The turning sleeve of the development roller thencarries the developer past the doctor blade [E].The doctor blade trims the developer to thedesired thickness and creates developer backspillinto the cross-mixing mechanism. Thedevelopment roller continues to turn, carrying thedeveloper to the OPC drum. When the developerbrush contacts the drum surface, the negatively

[B]

[C]

[D]

[E]

[A]



charged areas of the drum surface attract andhold the positively charged toner. In this way, thelatent image is developed.

Negative bias is applied to the development rollerto prevent toner from being attracted to the non-image areas on the drum, which may have aresidual negative charge.

A toner density sensor [F] directly measures theamount of toner in the developer mixture.




Model A229 uses a double roller developmentsystem. Each roller has a diameter of 20 mmwhich is somewhat narrower than singledevelopment roller systems.

This system differs from single roller developmentsystems in that each development roller developsthe image in a narrower area and the image isdeveloped twice. Also, generally, the peripheral velocity of the development rollers relative to thedrum is less than with single rollers.

The internal parts are basically the same as thoseof the single roller system.

The operation is explained on the next page. [A]

[I]

[C]

[D] [E]

[F][G]

[H]

Paddle Roller [A]Upper Development Roller [B]Lower Development Roller [C]Toner Density Sensor [D]Developer Agitator [E]Toner Auger [F]Development Filter [G]Toner Hopper [H]Doctor Blade [I]

[B]



The paddle roller [A] picks up developer andtransports it to the upper development roller [B].Internal permanent magnets in the developmentrollers attract the developer to the developmentroller sleeve. The upper development roller carriesthe developer past the doctor blade [C]. Thedoctor blade trims the developer to the desiredthickness and creates backspill to the crossmixing mechanism.

In this machine, black areas of the latent imageare at a low negative charge (about –150 V) andwhite areas are at a high negative charge (about –950 V).

The development roller is given a negative bias toattract negatively charged toner to the black areasof the latent image on the drum.

The development rollers continue to turn, carryingthe developer to the drum [D]. When thedeveloper brush contacts the drum surface, thelow-negatively charged areas of the drum surfaceattract and hold the negatively charged toner. Inthis way, the latent image is developed.

[A]

[D]

[C]

[B]



Mono-Component Development

OverviewThe monocomponent development process uses toner only with no carrier. Monocomponentdevelopment systems are used mainly in small photocopiers with a low copy rate.

Advantages:

• Development unit structure is simple and compact.

• Toner density control is unnecessary.

Disadvantages:

• Unsuitable for high speed developing

• Suitable for low-volume copying only because the development unit parts wear out relativelyquickly.



Basic ProcessThe illustration to the right (from model A027) showsa typical monocomponent development system. Thissystem does not use a magnetic brush, and as aconsequence, there isn’t a doctor gap or photo-conductor gap. The development roller [A] directlycontacts the OPC belt [B] and the toner meteringblade [C].

As the development roller turns past the tonermetering blade, only a thin coating of positivelycharged toner particles stays adhered to thedevelopment roller. After that, the development rollerturns past the OPC belt. The negatively chargedlatent image on the OPC belt's surface attracts thetoner from the development roller, making the imagevisible on the OPC surface.

A027blackdev.pcx

[B]

[C]

[A]



Development Roller and Toner Metering BladeThe typical development roller used in the mono-component process has two layers. At the corethere is a conductive layer [A] to which thedevelopment bias is applied. Around that, there isa magnetic rubber layer [B], which has closelyspaced, alternating north and south magneticpoles. The development roller rotates at a highspeed—typically greater than 300 rpm.

The toner metering blade [C] is made of an ironbased material. It is attracted against the develop-ment roller by the magnetic field of the magneticrubber layer. The toner metering blade vibratesbecause of rapid changes in the magnetic field asthe roller turns. The vibration allows toner to passby and prevents foreign matter from being caughton the edge of the metering blade.

Toner particles [D] receive a positive triboelectric charge as they move past the toner metering blade.This charge is created by the rubbing action of the development roller, toner, and toner meteringblade.

The monocomponent toner used with this type of roller is composed of resin and ferrite. Attractionbetween the ferrite and the magnetic rubber layer causes the toner to adhere to the development

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roller. (Typically, this kind of toner also has high electrical resistance, which gives it gooddevelopment and image transfer characteristics, even under high humidity conditions.)

FEED Development RollerSome monocomponent development units use theFEED development technique. (FEED stands for“floating electrode effect development”.) Thissystem is similar to that discussed in the previoussection; however, the development roller has aninsulating layer over the magnetic rubber layer.Floating electrodes [A] are embedded in theinsulating layer [B]. (They are called floatingelectrodes because they “float” electrically in theinsulating layer.)

This type of system is suitable for use with tonerscontaining little or no ferrite (for example colortoners). The floating electrodes take on atriboelectric charge opposite to that of the toner,and thus, attract the toner to the developmentroller.

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Double Development Roller ProcessThe development of the double development roller method for monocomponent development was intwo stages. The double development roller process was originally developed as an adaptation of thenormal monocomponent process for use with an OPC drum. Since the development roller was ametal roller with magnetic strips, it wasn’t suitable for direct contact with a hard OPC surface.

Because of this, a rubber roller was placed between the drum and the metal roller. This rubber rollerwas called the development roller, and the old metal-and-magnet roller was called the tonerapplication roller. This is the type of development system used in model H523. (See example 1below for details.)

In the second stage, the double roller process was modified for use in replaceable cartridges. In suchcartridges, the toner application roller is a sponge. It is not magnetic. It just picks up toner andapplies it to the development roller. The development roller is similar to the one used in the firststage. The toner-metering blade was moved to the development roller, because the application rollerdoes not apply an even layer to the development roller.

Also, the potential difference (bias) between the application roller and development roller wasreduced in the second stage. Less potential difference is required because it isn’t necessary toovercome the attraction of the magnets. This is the type of development system used for modelsH545 and G026/G036. (See example 2 below for details.)



Example 1: Model H523

Toner is attracted to the toner application roller [A]because it has a magnetic layer. A thin coating ofnegatively charged toner particles adheres to thetoner application roller as it turns past the tonermetering blade [B].

During image development, a bias voltage of -700 Vis applied to the toner application roller and anotherbias voltage of -400 V is applied to the developmentroller [C]. This 300 volt difference in electricpotential moves the toner from the toner applicationroller to the development roller.

The development roller and OPC drum touch eachother with a slight amount of nip and rotate in thesame direction. The exposed areas on the drum [D]are at –100 volts. The development roller appliestoner to these areas of the latent image as the drumand development roller rotate. The developmentroller is made of a soft rubber so it does not damagethe surface of the drum.

The speed ratio (peripheral velocity) between thedrum, development roller, and the toner application

2RMCDev1.pcx

[B]

[C]

[D]

[A]



roller is 1 : 1 : 3. The toner application roller rotates three times as fast as the development roller, soit deposits a layer of toner three times as thick on the development roller. This leads to a clearerimage. Also, the toner application roller rotates in the opposite direction to the development roller,which helps to keep the toner level on the development roller.

Example 2: Models G026/G036

The toner application roller [A] supplies toner to thedevelopment roller [B]. The toner application roller is asponge roller. (Unlike the magnetic metal roller in example1.) A thin coating of negatively charged toner particlesadheres to the development roller as it turns past the tonermetering blade [C].

During printing, a bias voltage of –650 volts is applied tothe toner application roller and another bias voltage of -400volts is applied to the development roller. This 250-voltdifference in electric potential moves the toner from thetoner application roller to the development roller. Theexposed area on the drum [D] is at –200 volts. The development roller applies toner to these areasof the latent image as the drum and development roller rotate in contact with each other.

Since the development roller carries a thin layer of toner, it has to turn faster than the drum in orderto supply sufficient toner. Peripheral velocity is 1.38 times the peripheral velocity of the drum.

G025D709.wmf[B]

[C]

[D]

[A]



Development Bias

When a photoconductor (photosensitive drum or belt) is exposed, the charge decreases in thesections that receive light, corresponding to the white sections of the document. However, exposuredoes not eliminate the charge completely, and there is always a small residual charge on thephotoconductor. To prevent toner from being attracted to the non-image areas and thus causingtoner background on copies, the development roller is charged with a bias voltage greater than theresidual voltage on the photoconductor. This bias voltage is opposite in polarity to that of the toner;so, its attraction is greater than that of the residual voltage on the photoconductor.

In some machines, the bias voltage is also used to control image density. The higher thedevelopment bias voltage is, the less toner is attracted to the drum surface.

In the past, the most common copy process used a positively charged selenium drumphotoconductor, negatively charged toner, and a positive development bias. However, recentproducts use a negatively charged organic photoconductor (OPC) and positively charged toner; so,the development bias is negative.

NOTE: The calculation of the actual value of the development bias can be quite complex andvaries from machine to machine. Various compensating factors—for example for residualvoltage changes, temperature, original background, drum wear, magnification, and manyother factors—may be calculated by the machine’s CPU depending on the details of themachine’s process control. (For more details, see the Process Control section or refer tothe service manual of the product you are interested in.)



Example: Model A246

The high voltage control Board [A] applies thenegative development bias to both the lowersleeve roller and upper sleeve roller through thereceptacles [B] and the sleeve roller shaft [C].

The development bias prevents toner from beingattracted to the background of the non-imageareas on the OPC drum where there is residualvoltage. In addition, the development biasadjusts image density according to theconditions the customer selected.

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[A]

[B] [C]



Crossmixing

The illustrations above show a standard cross-mixing mechanism. Most dual componentdevelopment systems use a mechanism like this to keep the toner and carrier evenly mixed. Thismechanism also helps agitate the developer to prevent developer clumps from forming and helpscreate the triboelectric charge (an electric charge generated by friction) on the toner and carrier.

The developer on the turning development rollers [A] is split into two parts by the doctor blade [B].The part that stays on the development rollers forms the magnetic brush and develops the latentimage on the drum. The part that the doctor blade trims off goes to the backspill plate [C].

[A]

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[B]

[C]

[D]

[E]

[F][A]

[C][B]

[F]

[D]

[E]

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As the developer slides down the backspill plate to the agitator [D], the mixing vanes [E] move itslightly toward the rear of the unit. Part of the developer falls into the auger inlet and the auger [F]transmits it to the front of the unit.

The agitator moves the developer slightly to the front as it turns, so the developer remains evenlydistributed in the development unit.

Development Seal

Development units have several seals to prevent toner from spilling out into the copier. Usually thereare an upper (or inlet) seal, a lower seal, and side seals. In some cases, the upper seal is a brushseal and actually contacts the drum. In other development units, the upper seal is positioned close tothe drum to prevent particles from scattering upward. The development unit side seals, are in contactwith the drum ends (out of the image area) preventing toner scattering from the ends of the unit. Thelower seal is positioned to catch falling particles.



Toner Supply

In order to keep the toner density (ratio of toner to carrier) constant the development mechanismmust have a way of adding toner to the developer. This is called the toner supply mechanism.

The toner supply mechanism cannot just dump toner into the development unit. To avoid fluctuationsit must add small, measured amounts of toner in response to the toner density control system. (AlsoseeToner Supply Control in the Color Development section.)

There are many ways of designing a toner supply system. Here we will look at a couple of standardmechanisms.


This machine uses a toner bottle that has a spiralgroove in it. When the toner supply drivemechanism is activated, the toner bottle rotatesand the groove moves toner to the mouth of thebottle, where toner spills into a small hopper.Turning mylar blades move the toner to anopening in the side of the hopper and the tonerdrops into the development unit. The amount oftoner added depends on the length of time thatthe toner supply mechanism rotates.

Toner supply mechanisms similar to this one areused in many machines. A193d020.wmf




The illustration to the right is an example of the mostcommon structure for a toner supply system. Thetoner hopper, which is larger than the one in theprevious example, is mounted on top of thedevelopment unit and runs the full length of thedevelopment unit.

An agitator [A] inside the toner hopper stirs the tonerto prevent clumps from forming.

The toner supply roller [B] blocks the opening to thedevelopment unit. When the toner supply rollerrotates, the grooves on the toner supply roller catchthe toner. Then, as the grooves turn past theopening, the toner falls into the development unit.

A246D644.WMF

[B]

[A]



Toner Density Control

The toner density control system senses the density of toner in thedeveloper mixture and activates the toner supply mechanism to addtoner when the ratio of toner to carrier becomes too low. Somemachines measure the toner density directly, others use an indirectsensing method, and still other machines use a combination ofdirect and indirect sensing.

Indirect SensingThe CPU indirectly checks toner density by sensing the imagedensity of a sensor pattern developed on the photoconductor.

During image density check cycles, the sensor pattern is exposedprior to exposure of the original. After the sensor pattern isdeveloped, its reflectivity is checked by the image density sensor [A](which is a photosensor). The CPU notes the strength of reflectivity.If the reflected light is too strong, indicating a too low toner densitycondition, it adds toner to the development unit.

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Direct SensingThe illustration to the right is an example of asensor used to directly measure the amount oftoner in developer. (From model A163)

The active sensor element is a very smalltransformer with three coils. When iron ferrite(carrier) is near the sensor element, theinductance of the coils changes, causing thecurrent through the transformer to change. Asthe amount of toner in the developer increases,the effect of the carrier particles decreases andthe voltage applied to CN104-A10 decreases.Conversely, when the toner concentrationdrops as toner is used up, the effect of thecarrier on the sensor coils increases and thevoltage at CN104-A10 increases.The CPU monitors the output at CN104-A10and when the voltage at CN104-A10 reachesa level that indicates toner density is too low,the toner supply mechanism adds an appro-priate amount of toner to the developer.

TDSensor.pcx

Toner Density Sensor Main Board

Control

Circuit

1

2

3

4

CN104-A11

CN104-B20

CN104-A10

CN104-B21

[12V]

GND

Coils

TS. FB

TS Control

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Toner End Detection

Some machines detect the toner end condition directly using a sensor or mechanical detectionmechanism. Others detect toner end indirectly based on the toner density.

Indirect Toner End DetectionSome machines use the output of the image density sensor to determine when it is time to add toner.(Examples are models A166 and A110.) Other machines use the output from the toner densitysensor. (An example is model A219.)The details of how the CPU decides when toner has run outdepend on the control program and vary from machine to machine. However, there are some overallsimilarities.

Toner end detection proceeds in two steps. First, if toner density stays too low for a certain numberof machine cycles, the CPU decides that a toner near end condition exists. In this condition, the CPUgenerally monitors the toner density more closely and increases the amount of toner supplied to thedeveloper. Copying or printing is possible during the near end condition, but generally an Add Tonerindicator blinks.

The machine proceeds to the second step if the toner near end condition persists for more than apredetermined number of cycles—typically 50 copies. The CPU then determines (based on thecontrol program) that a true toner end condition exists, and it inhibits copying and lights an AddToner indicator.



Example 1: Model A110 (Image density sensor)

Toner Near End Condition

When (Vsp/Vsg x 100) becomes greater than 22.5, the toner density detection cycle changes fromevery 10 copies to 5 copies. When this condition is detected three times consecutively, the tonersupply ratio becomes two times the amount of toner supply level 4. The resulting toner supply ratio is60%, and the ID sensor data is 236. Then, when this condition is detected five times consecutively,the CPU determines that it is the near end condition and starts blinking the Add Toner indicators.

Toner End Condition

After the Add Toner indicator starts blinking (Near Toner End Condition), the operator can make 50copies. If the toner cartridge is not replaced within 50 copies, copying is inhibited and a toner endcondition is determined. In this condition, the Add Toner indicator lights.

Example 2: Model A219 (Toner density sensor)

Toner Near End Condition

If the CPU detects toner supply level 6 (VT ³ VTS + 4S/5) five times consecutively, the toner endindicator blinks and the machine goes to the toner near end condition.

In this condition, the toner supply motor is energized for 10 seconds for every copy (this time can bechanged using SP35). Also, the toner supply motor stays on continuously between pages of a multi-copy job.



If a toner sensor voltage lower than VTS + 4S/5 is detected twice consecutively while the tonersupply motor is on, the machine recovers from the toner near end condition. Also, if this condition isdetected during the normal copy cycle, the toner near end is canceled.

Toner End Condition

If toner supply level 6 is detected, the machine supplies toner between copies and for 10 secondsafter the copy job is finished (as explained above). While the toner supply motor is on, if the CPUdetects toner supply level 7 (VT ³ VTS +S) three times consecutively, a toner end condition isdetected and copier operation is disabled.

If the toner sensor voltage stays at level 6 after the toner near end condition is detected, 50 morecopies can be made. After 50 copies, the toner end indicator lights and copying is disabled.



Direct Toner End DetectionToner end is sensed directly using either a sensor or a mechanical mechanism. Here we will look atone example of each

Toner end sensorMany machines use a piezoelectric sensor [A] to detectwhether or not there is sufficient toner in the toner supplyunit. This type of sensor is sensitive to pressure. Pressurefrom toner in the toner supply unit causes the sensor tooutput a high signal. When there is not much toner in theunit, the pressure of toner on the toner end sensor becomeslow and the sensor outputs a low signal (0V). To preventfalse readings, the toner end sensor is cleaned by a spring[B] on the toner agitator shaft.The details of what happens when the sensor outputs a lowsignal vary depending on the machine; however, there arethree major steps. First; the toner bottle turns to add toner tothe toner supply unit. Then, if the sensor still has a lowoutput after a specified interval, the machine changes to thetoner near-end condition and the Add Toner indicator startsblinking. Finally, if the toner near-end condition persists for aprogrammed number of machine cycles (generally 50copies), the machine enters the toner end condition andoperation is disabled.

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[B]

[A]



Mechanical Toner End Detection

Several mid and high volume photocopiers use themechanism shown to the right to check the amount oftoner remaining in the toner tank.

The toner near end feeler [A] has a magnet [B] and isinstalled on the toner mixing vane drive shaft [C]. Thetoner near end sensor [D] is located underneath thetoner tank (outside) and has a sensor actuator [E], whichalso has a magnet. When the toner tank has enoughtoner, the toner near end feeler does not lower due tothe resistance of toner.

When the to amount of toner remaining in the toner tankbecomes below approximately 250 grams, the near endfeeler lowers and magnetic repulsion pushes down thesensor actuator. This actuates the toner near endsensor. When the main PCB senses the toner near endsensor actuation three times in a row, the toner near endcondition is displayed on the CRT screen to let theoperator know to replace the toner cartridge. In the tonernear end condition, copies can be made until the IDsensor detects toner end.

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[B]

[C]

[D]

[E][A]


Photocopying Processes Image Transfer And Paper Separation

Image Transfer And Paper Separation

Overview

The transfer and separation process can be brokendown into the three areas shown to the right.

Area A: Pre-transferJust before the image transfer process starts,guides direct the paper against the photosensitivesurface of the drum (or belt). The mechanism isstructured so that the transfer charge does notreach this area, and therefore, the paper canachieve complete contact with the photoconductorbefore image transfer starts.

Area B: Image TransferThis is the area where the image is actuallytransferred from the photoconductor to the paper.Generally, an electrostatic charge is applied to theback of the paper to pull the oppositely chargedtoner from the photoconductor to the paper.

Area C: Paper SeparationThe paper separates from the photoconductor afterthe toner image is transferred. This is usually

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achieved by applying an ac corona to the back of the paper to eliminate the previously appliedtransfer charge. Pick-off pawls are also used to physically separate paper of low stiffness from thedrum.



Corona Transfer And Separation

Image Transfer

In the image transfer process, the toner image onthe photosensitive material (drum surface) ismoved onto the copy paper.

As the paper enters the transfer area, a coronaapplies a charge to the reverse side of the copypaper [A]. This charge induces an oppositeelectrostatic charge in the drum’s substrate [B](usually aluminum) The resulting electrostaticforce holds the paper close against the drum. Thishelps the transfer process.

The charge on the reverse of the paper alsoattracts the toner because the polarity is opposite

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[B]

[A]

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to the charge on the toner. Since, this attractiveforce (FA) is designed to be greater than theattractive force holding the toner to the drum (FB),the toner attaches to the paper

Paper SeparationDuring the separation process, the copy paperwith the toner image on it separates from thephotoconductor. The paper can be separatedeither mechanically or electrostatically (or by acombination of both). Recent Ricoh copiers usethe electrostatic method.

The charge given to the paper during the imagetransfer process causes the paper to cling to thephotosensitive material. This makes it difficult tostrip the paper from the drum. Therefore, an ACcorona applied by the separation corotronneutralizes the charge on the paper in order tobreak the attraction between the drum and thecopy paper. The paper then separates from thedrum because of the rigidity and the weight of thepaper.

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The pick-off pawls provide a mechanical backupfor the separation process. Normally, they are notneeded. However, when the corona separationfunction is not sufficient for some unknownreason, they force paper separation.

The section with the diagonal lines in theillustration on the right shows the areas where thecharge on the paper is eliminated by theseparation corotron. This requires the use of twowires to create a wide-angle corona.

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Belt Transfer and Separation

Advantages Of The Transfer Belt SystemMany models use a transfer belt unit instead of a transfer and separation corona unit. The transferbelt process has the following advantages:

• Since the copy is held closely against the transfer belt, there is little chance of the paper liftingoff of the belt during transport, making it less likely that creases and jams will be produced atthe fusing unit inlet, and also reducing image blurring.

• As the paper adheres to the belt during transport, the transport performance is stable, evenwith smaller paper sizes, such as postcards.

• Because the belt and printing paper maintain close contact, an excellent separationperformance over a wide range of paper types is ensured.

• As high voltage charge wires are not used, there is no problem with electrical leaks fromcharge wires.

• There is no trailing edge white margin on copies.

• It improves the printing efficiency and also enhances the printing performance on paper with ahigher moisture content.

• A transport fan is not required.



tsbelt1.pcx

Belt Transfer and Paper Separation MechanismThe following is a discussion of the operation of a typical transfer belt mechanism. This example isbased on the Phoenix series (model A156).

1. The registration rollers [A] start feeding thepaper [B] to the gap between the OPCdrum [C] and the transfer belt [D] at theproper time to align the leading edges ofthe paper and the image on the drum. Thetransfer belt does not contact the OPCdrum at this moment (the on-off lever [E]pushes down the transfer belt lift lever [F]).



tsbelt2.pcx

2. Before the leading edge of the paper reachesthe gap between the transfer belt and the OPCdrum, the transfer belt contact clutch [G]rotates one third of a complete rotation torelease the on-off lever. Then, the transfer beltlift lever pushes up the transfer belt as a resultof spring pressure. The contact width [H] isabout 4 ~ 5 mm.

3. Then a negative potential of –1.0 ~ –6.5kilovolts is applied to the transfer bias roller [I].The negative charge attracts the positivelycharged toner [J] from the OPC drum. It alsoattracts the paper and separates the paperfrom the OPC drum.

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4. After the image transfer is completed, the charge onthe transfer belt holds the paper on the transfer belt.Excess charge on the paper and the transfer belt isdischarged during rotation via the grounded idleroller [K].

When the transfer high voltage supply board [L]inside the transfer belt unit provides high voltage tothe transfer bias roller, a small current (I2) flows toground via the transfer belt, the paper, and the OPCdrum. It is important that this current stays constanteven if the paper, environmental conditions, or thetransfer belt surface resistance change. The positivefeedback of I1 to the power supply board causes thevoltage to increase and decrease with I1 so that (I2)remains constant. (The relationship is I2 = I– I1.)

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trandrum.pcx

Drum Transfer

Basic ConceptSome color copiers (models A072, A030) use a drum to transfer the image from the photoconductorto the paper. This is actually a variation of the corona transfer and separation processThis process uses a second drum, the transfer drum, which rotates in contact with the OPC drum(photoconductor). The copy paper is held on the surface of the transfer drum, which makes severalrotations to transfer the various colored toners. The image is transferred electrostatically using acorona.

Drum Transfer And Paper Separation MechanismExample: Model A072

The registration rollers feed the copy paper to thetransfer drum, where the leading edge of thepaper is secured by a clamp. The transfer coronaunit [A] is located inside the transfer drum unit. Ahigh negative charge is applied to the transfercorona wire and the corona wire generatesnegative ions. The negative ions are applied to thecopy paper and the negative charge attracts thepositively charged toner away from the drum andonto the paper. At the same time, the copy paperis electrostatically attracted to the transfer sheet.



trandrum.pcx

The transfer drum motor [D] drives the transferdrum directly. The number of transfer cyclesdepends on the number of colors being copiedand the copier mode.

After the necessary number of transfer cycles, theclamp releases the leading edge of the paper andlifts it slightly. The leading edge of the papercatches on the pick-off pawls [B], which separatethe paper from the transfer drum. The separationcorona wire applies an AC charge to the paper inorder to break the attraction between the paperand transfer drum.

The cleaning unit [C] for the transfer drum islocated at the bottom of the transfer drum. Duringthe copy cycle, the cleaning unit is not in contactwith the transfer drum. After the copying sequenceis completed, the cleaning unit moves against thetransfer drum. This cleaning unit removes tonerthat gets on the transfer sheet as the result ofpaper misfeeds.

Note: The "transfer sheet" is a thin sheet ofpolyester film that forms the surface of thetransfer drum.



Pre-Transfer Potential Reduction

PurposeTo improve image transfer efficiency, prevent offset images and improve cleaning efficiency, theelectric potential on the photosensitive material surface is reduced, after the development process.There are two commonly used methods—the pre-transfer lamp method and the pre-transfer coronamethod.

Pre-Transfer Lamp (PTL)

After the latent image is developed but before the image is transferred to the copy paper, thephotoconductor surface is illuminated by a lamp. This illumination functions in much the same way asthe exposure process. The light neutralizes some of the charge on the photoconductor, and thusreduces the attraction of the toner to the photoconductor. This prevents the toner particles frombeing re-attracted to the photoconductor during the paper separation process. It also makes imagetransfer and paper separation easier.

Pre-Transfer Corona (PTC)

Some copiers use an alternating current corona prior to image transfer. This is referred to as the pre-transfer corona unit or PTC. The ac charge decreases the charge on the drum and makes paperseparation easier.

Ricoh uses the PTC process only in higher speed copiers that require quick image transfer andpaper separation.



Example: Models A170/A171

Model A170/A171 (Thunderbird) copiers useboth a PTC and a PTL.

The pre-transfer corona (PTC) [A] and pre-transfer lamp (PTL) [B] are used to preventincomplete toner transfer and pick-off pawlmarks on the copy.

To prevent incomplete toner transfer, the PTCreduces drum potential by applying an accorona. The PTC also applies a dc negativecharge at the same time to keep the tonerpotential negative.

The PTL further reduces the drum potential.Since the PTC gave a negative charge notonly to the toner but also to the non-image (notoner) areas on the drum, PTL reduces thenegative charge on the drum, which mayattract copy paper and cause pick-off pawlmarks.

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Pick-off Pawls

PurposePick-off pawls are mechanical “fingers” that forcibly strip copy paper off of the photoconductor. InRicoh photocopiers they are usually employed as a safety device to prevent paper from wrappingaround the drum.

Example: Model A053

Touch-and-Release Mechanism

The pick-off solenoid [A] energizes just after theregistration rollers turn on. The pick-off lever [B]rotates counterclockwise (rear view) and pushesthe pawl shaft pin [C]. The pawl shaft [D] thenrotates clockwise and the pick-off pawls [E] touchthe drum. The pawl springs [F] hold the pick-offpawls on the shaft and prevent them from touchingthe drum too strongly. When the leading edge ofthe paper passes the pick-off area and just before itreaches the fusing unit, the pick-off solenoid turnsoff. The pick-off shaft spring [G] then rotates thepick-off lever to move the pick-off pawls away fromthe drum.

pickoff1.



Side-to-Side Movement

The pick-off pawls do not always contact thedrum in the same place but instead move slightlyto the side on each copy cycle. The pick-off pawlshaft [H] and the cam rider [I] are joined by aone-way bearing [J]. Each time the pick-off pawlsolenoid turns on, the one-way bearing causesthe cam rider to turn together with the pick-offpawl shaft. As the cam rider turns, it and the pawlshaft are forced to move laterally by a cam [K].When the pawl shaft rotates the pawls away fromthe drum, however, the cam rider does not turn.Pawl lateral movement is 0.1 to 0.2 millimeter percopy cycle. After moving about 8 millimeters, thecam rider passes the lobe of the cam and thepawl shaft is returned to its start position by thepawl shaft spring [G].

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Curvature SeparationSome machines do not have a paper separationmechanism. In the illustration to the right (modelA027), the master (OPC belt) turns at a sharpangle (approximately 90 degrees) just after thetransfer point. Due to the paper’s stiffness, itcannot make this sharp turn and separateswithout any assistance.

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Master

Paper



Transfer Roller + Discharger

Process PrinciplesSome machines use a transfer roller rather than a corona or belt to transfer the image to the copypaper.

Copy paper is fed between the transfer roller and the surface carrying the toner image (either a drumor a transfer belt). The transfer roller is given a charge opposite to the charge on the toner; so, thetoner is attracted to the paper. After image transfer, a discharger removes the charge given to thepaper by the transfer roller, and this allows curvature separation to take place.


Instead of using a transfer wire or a transfer belt,this machine uses a transfer roller [A], whichtouches the drum surface.

The high voltage supply board supplies a positivecurrent (approximately +15 mA) to the transferroller. The roller has a high electrical resistance, soit can hold a high positive electrical potential toattract toner from the drum onto the paper.

There is a discharge brush [B] after the transferroller. The curvature of the drum and the dischargebrush help the paper to drop away from the drum.

[A]

[B]a193d021.wmf



Example 2: Models A172/A199

The transfer roller [A] contacts the transfer belt [B] andstarts rotating at the same speed as the transfer belt.Copy paper is fed to the nip band between the transferbelt and transfer roller aligned with the lead edge ofthe full color image. A high positive voltage is appliedto the transfer roller to attract toner onto the paper.

A high ac voltage is applied to the discharge plate [C].This discharges the remaining electricity on the paperto help the paper separate from the transfer belt.

[C]

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[A]

[B]


Photocopying Processes Cleaning

Cleaning

Overview

Cleaning refers to the process of removing any toner remaining on thephotoconductor (drum or OPC belt) after the imaging process is completeto prepare the photoconductor for the next copy/print cycle. The cleaningstep also removes any paper dust on the photoconductor surface.

Cleaning is necessary before a new copy cycle or print cycle can start. Ifthe cleaning step were not included in the copy process, the background ofimages would become progressively darker and dirtier.

All cleaning systems use a cleaning blade or a cleaning brush or both.Additionally, all cleaning systems have a mechanism for collecting andstoring (or recycling) the toner cleaned from the photoconductor.

The most common cleaning systems use blades, and these are furtherdivided into trailing-blade cleaning and counter-blade cleaning systems.

Cleaning brushes all rotate in contact with the photoconductor. There arealso two types of cleaning brushes—fiber brushes and magnetic brushes.

Some cleaning systems also use a corona (pre-cleaning corona) to preparethe drum and toner for cleaning.

We will look at examples of all of these mechanisms in this section.05050510.pcx

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Counter Blade

Counter blade cleaning is the most common method usedin modern copiers. In comparison to the trailing blademethod, counter blade cleaning causes less wear on thecleaning blade. Also, the blade has less of a tendency toride over toner particles, significantly improving thecleaning performance.

Example: Model A193

The illustrations to the right show a typical counter bladecleaning mechanism.

The cleaning blade [A] removes any toner remaining onthe drum after the image is transferred to the paper. Thecleaning blade scrapes off the toner remaining on the drumand it falls onto the toner collection coil [B].

To remove the toner and other particles that areaccumulated at the edge of the cleaning blade, the drumturns in reverse for about 5 mm at the end of every copyjob, A193d529.wmf

A193d010.wmf

[B]

[A]



Counter Blade + Brush

Some copiers, especially high-speed models, use acleaning brush in combination with a counter cleaningblade. This increases the cleaning efficiencycompared to systems using only a counter blade. Thecleaning brush has a support function. The counterblade is the main cleaning component.

Example: Model A171

A cleaning brush [A] supports the cleaning blade [B]to improve cleaning. A looped-type brush is used forbetter efficiency.

The brush removes some of the toner from the drumsurface and collects the toner wiped off the drum bythe cleaning blade. The flick bar [C] and the flickroller [D] mechanically remove toner on the cleaningbrush. Toner is transported to the toner cartridge bythe toner collection coil [E].

To remove the accumulated toner at the edge of thecleaning blade, the drum turns in reverse for about 20mm at the end of every copy job.

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[B]

[C]

[D]

[E]

[A]



Trailing Blade + Brush

Many older copiers use a cleaning brush incombination with a trailing cleaning blade. Typically,in such systems, the brush does most of the cleaningwith the cleaning blade as a supporting cleaningmechanism.

Electrostatic attraction is an important part of this typeof cleaning system. A pre-cleaning corona is used toprepare the toner for removal and a bias is applied toattract the toner.

Example: Model A029

The illustration to the right shows the majorcomponents in a cleaning unit that uses a brush [A]and a trailing type blade [B] for cleaning.

The first step in the drum cleaning process is theapplication of the pre-cleaning corona [C]. The pre-cleaning corona has both ac and dc components. Theac component makes drum cleaning more efficient byreducing the drum’s potential and weakening theelectrical attraction between toner and the drum. Thedc component of the corona gives a uniform negative

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[G]

[B]

[C]

[D]

[E]

[F]

[A]



charge to the toner particles.

Next, the drum rotates past the cleaning brush. The brush moves in the opposite direction to thedrum at the contact point. The brush, which is made of conductive acrylic carbon, receives a positivecharge from the bias roller [D]. The brush removes the toner from the drum by both rubbing actionand electrostatic attraction. The bias roller has a charge of +300 volts which attracts the negativelycharged toner from the brush. The bias roller blade [E] scrapes off the toner from the bias roller.

Finally, the cleaning blade scrapes off any toner, paper dust, or other foreign material remaining onthe drum. The toner collection coil [F] transports the toner to the rear end of the cleaning unit, Fromthere, a collection mechanism returns the toner to the toner cartridge.

Paper dust or toner build up on the blade edge decreases the efficiency of the cleaning blade. Toprevent this problem, the blade cleaner [G] (a strip of mylar) cleans the edge of the blade each timepressure is released.



Magnetic Brush

Magnetic brush cleaning is basically “development in reverse”. This method uses a magnetic rollerand carrier to electrostatically lift the toner off of the photoconductor.

Example: Models A030 and A072

The illustrations to the right and on the next page showthe cleaning unit used in models A030 and A072.

To ensure OPC drum cleaning, the pre-cleaningcorona [A] applies an ac voltage with a positive dc biasto the surface of the drum. This gives the residualtoner a uniform positive charge and neutralizes thenegative charge on the drum.

The cleaning roller [B] looks like and operates similarlyto a magnetic brush development roller. However, theattractive forces work in reverse. Internal permanentmagnets in the cleaning roller attract cleaning carrier tothe cleaning roller sleeve. The cleaning roller sleeveturns and carries the cleaning carrier to the OPC drum.

The cleaning carrier has a negative triboelectric chargeas the result of contact between the carrier and tonerparticles in the carrier. (New cleaning carrier contains A030cln1.pcx

[C]

[A]

[D]

[E][B]



1% toner.) This negative charge attractsthe positively charged toner particlesfrom the drum surface. A –150 V DCbias is applied to the cleaning roller toattract more toner particles from thedrum.

The cleaning bias roller [C] (called a“scavenging roller” in some machines)is near the cleaning roller. The cleaningbias roller receives a –500 V charge,which is strong enough to separate thetoner particles from the cleaner carrieron the cleaning roller and attract themto the cleaning bias roller. The cleaningcarrier remains on the cleaning roller forthe next cleaning cycle.

The bias roller blade [D] scrapes toneroff the bias roller. The toner collectioncoil [E] transports the toner to the rearside of the cleaning unit, where it dropsinto the toner collection bottle [F].

A030cln3.pcx

A030cln2.pcx

[C]

[D]

[E]

[F]

[B]



Used Toner Collection and Recycling

Once toner is cleaned from the photoconductor, something must be done with it. There are twooptions— (1) collect the used toner for later disposal or (2) recycle it. There is a cost versus imagequality trade-off between the two options.

Recycling has the obvious advantage of reducing toner consumption and thus reducing cost percopy/print. However, even if it is carefully done, recycling to some extent damages the toner anddegrades its triboelectric characteristics. Also, recycled toner tends to stick together and formclumps, and paper dust is collected along with the toner. For these reasons, image quality tends tobe a problem in machines that recycle toner. This presents a challenge for engineers.

On the other hand, simply collecting the used toner prevents fewer design problems and makes iteasier to maintain copy quality. However, the copy per cost increases. Also, the used toner containertakes up space inside the machine, and some provision must be made for periodic disposal of theused toner.



Used Toner CollectionThe location of the toner collection unit or usedtoner bottle varies. Smaller machines tend to havesimple designs. For example, machines that use all-in-one cartridges such as model G026 (shown to theright) have the used toner tank inside the cartridge.Such machines do not have a used toner overflowdetection mechanism because the used toner tank[A] is large enough for the lifetime of the tonercassette.

Other machines, especially low volume and midvolume products, mount the used toner tank directlyon the cleaning unit. An example is model A110,shown to the right. The used toner tank [A] of thismachine must be emptied periodically. The tank hasa toner overflow detection mechanism [B] that stopscopier operation when the used toner tank gets full.When the tank gets full, the pressure of the usedtoner pushes up a movable plate mounted in the topof the used toner tank. As this plate moves up, itraises the toner overflow actuator. When the actuatormoves into the toner overflow sensor.

G025D513.wmf

[A]

A110overflow.pcx

[B]

[A]



Larger machines have to transport used toner toa toner collection bottle. Typically, a helical coildoes this.

For example the toner recover mechanism ofmodel A174 (pictured to the right) has a tonercollection coil [A], which moves used toner fromthe cleaning unit to the toner collection bottle[B]. The toner collection bottle capacity isenough to hold used toner from making 6 km(capacity: 4000 ml) copies. (This is a largeformat copier.)

A toner overflow sensor [C] detects when theused toner tank is full.

A174D524.wmf



Recycling Used TonerThere are many configurations for toner recyclingsystems. All of them use helical coils to collect andtransport the toner from the cleaning unit. Some of themreturn the used toner directly to the development unit.Others, mix the old toner with new toner first. We will lookat a few examples.


In this model, toner recycling is completely internal to aphotoconductor unit (PCU). See the illustrations.

The cleaning blade removes any toner remaining on thedrum after the image is transferred to the paper. Thismodel uses a counter blade system. The tonerremoved by the cleaning blade falls onto the tonercollection coil [A].

The toner collection coil transports the recycled tonerto the transport belt [B] at the front of the PCU. Thetransport belt carries the toner to mixing auger 2. Thetwo mixing augers [C] combine the recycled toner withthe developer and new toner from the toner bottle.

A193D016.wmf[B]

[C]

[A]

A193D010.wmf

[A] [C]



Example 2: Models A230/A231/A232

The cleaning blade removes any toner remaining onthe drum after the image is transferred to the paper.This model like the previous example uses a counterblade system. The toner is transferred to the tonercollection coil [A] by the toner collection plate [B].

The toner collection coil transports the used toner tothe opening [C] in the bottom of the PCU. Then, thistoner falls into the development unit with new tonercoming from the toner bottle and it is all mixed intothe developer by the paddle roller [D].

A231D507.wmf

[B]

[C]

[A]

A230D452.wmf

[D]

[A]

[C]




The toner recycling system of this modelhas a couple of unusual features. First, itrecycles not only the toner cleaned from thedrum but also toner cleaned from thetransfer belt. Second, it filters the recycledtoner.

Toner collection coils in the drum cleaningunit [A] and in the transfer belt cleaning unit[B] transport used toner to the tonertransport coil [C]. To ensure good tonerflow, a fin [D] breaks up the toner that dropsfrom the tube of the drum-cleaning unit. Thetoner transport coil moves the toner througha tube to the filtering unit [E].

The filtering unit separates useable tonerfrom toner that has adhered together intoclumps. The useable toner is returned to thedevelopment unit, and the waste toner goesto a used toner bottle.

A246D500.wmf

[B]

[C]

[D]

[E]

[A]


Photocopying Processes Quenching

Quenching

Overview

Quenching is the process that eliminates any residual electric charge remaining on thephotoconductor after the cleaning process. Quenching prepares the photoconductor for the chargestep of the next copy or print cycle.

Several different methods are used to quench the photoconductor. The most common method isphoto quenching using a lamp. Some machines use a combination of a dc corona and photoquenching. A few machines use an ac corona for quenching. The choice of quenching methoddepends on the type of photoconductor used and the details of the other steps of the copy process.

Photo Quenching

As the name implies, photo quenching uses the application of lightto reduce the resistance of the photoconductor and thus eliminatethe electrical charge. Photo quenching also stabilizes the drumsensitivity from the first cycle by pre-illuminating the drum.

Various types of lamp have been used for quenching lamps. LEDarrays are the most common; however, cold cathode tubes, neontubes, and fluorescent lamps have also been used.

• LEDs are inexpensive and compact, and it is easy to matchthe wavelength of the light to the spectral sensitivity of the q_lamp.pcx



photoconductor. However, LEDs output a relatively weak light.

• The cold cathode lamp has the characteristics of low power consumption and low heat outputcombined with strong, even light output covering a broad spectrum. However, it is moreexpensive (special power supply) than LEDs.

• The neon tube is cost effective; however, there is significant unevenness in the amount of lightoutput.

• Fluorescent lamps output a strong, wide spectrum light, but they are the most expensive.Fluorescent lamps are used for quenching only in very high-speed photocopiers.

Various types of filters may be used depending on the copy process and photoconductorcharacteristics. For example when using a cold cathode lamp and an OPC drum, a yellow filter isusually used to reduce ultraviolet light which would cause light fatigue on the OPC drum.



DC Corona and Photo Quenching

This type of quenching involves two steps.First, the pre-quenching corona (PQC)applies a positive charge to the drum. Thisneutralizes any negative charge remainingon the drum from the pre-cleaning corona.Then, the quenching lamp neutralizes thepositive charge. Two steps are requiredbecause the quenching lamp is lesseffective against negative charges thanpositive charges.

The quenching lamp also stabilizes thedrum sensitivity from the first cycle by pre-illuminating (pre-fatiguing) the drum. Themachine illustrated (model A029) uses acold cathode lamp as the quenching lamp.The cold cathode lamp has characteristicsof low power consumption and low heatoutput combined with strong light output.

In some machines (for example modelA053), the PQC and quenching lamp areapplied simultaneously.

PQC.pcx


Photocopying Processes Fusing

Fusing

Overview After the image transfer and paper separation steps, the image must be bound or “fixed” to the paper. Modern photocopiers and other machines (fax, printer) that use photocopier imaging processes, use resin based toners. To form a stable permanent image, the toner is heated to cause it to melt and soften. Simultaneously, pressure is applied to cause the toner to fuse with the fibers of the paper.

Heat-Roll Method The heat-roll method is the most common way that Ricoh products use to fuse the toner image to paper. It is used in all types of machines from the lowest speed to high speed. In the heat-roll fusing method, paper with dry toner particles on it moves between two rollers, the hot roller and the pressure roller. A quartz halogen lamp heats the hot roller from inside. When the paper comes in contact with the hot roller, the heat of the roller melts the toner. The pressure between the two rollers forces the melted toner into the fibers of the paper.

Copy paper

Hot roller

Fusing Lamp

Thermistor

Oil application

Stripper pawls

Pressure roller

IPS_255.wmf



The Hot RollerThe hot roller is a hard-surfaced, hollow, metal tube with a halogen lamp at its axis. Toner tends tostick to the hot roller as well as the paper. To minimize this tendency, the hot roller is coated withnon-stick Teflon.

Even with the non-stick coating, a small amount of toner still sticks to the hot roller. This tonercontamination must be removed or it will be applied to subsequent copies, giving an offset image ordirty copies. This is usually done with a cleaning pad or with a cleaning roller. In many machinessilicone oil is applied to the hot roller. The silicone oil acts as a lubricant and helps to prevent tonerfrom sticking. (Refer to Oil Supply and Cleaning below.)

The Pressure RollerThe pressure roller is a relatively soft roller made of silicone rubber. Silicone rubber is used becauseit is not easily damaged by the heat of the hot roller. Sometimes the roller surface is coated withTeflon. Since the pressure roller is soft, the pressure between the two rollers causes the pressureroller to deform slightly and creates a zone of contact called the “nip band”. The nip band extends thetime that the rollers are in contact with the paper and helps to force the melted toner into the copypaper. If the pressure roller were a hard roller, the paper would contact the hot roller at only one pointand the toner would not completely bond with the paper.

The hot roller and pressure roller are very slightly concave (spindle shaped) so that the pressurebetween them is a little greater near the ends than in the middle. This tends to pull the paper outwardslightly at the edges and helps to prevent creasing of the paper.



Fusing Belt Method The fusing belt method is similar to the heat roll method in that it uses heat and pressure to fuse the toner image to the paper. Although somewhat more costly than the heat-roll method, the fusing belt method is often used in color copiers and printers as it has less of a tendency to disturb or smear the layers of colored toner on the copy or print. Compared to the heat-roll method it has the following characteristics:

• The fusing belt [A] heats up quicker than a Teflon roller because it is heated by an aluminum heating roller [B]. (Fast-heating aluminum can be used because it does not touch the paper.)

• During a multi-page print job, the belt does not cool as quickly as a Teflon roller.

• The belt applies less pressure to the paper than a heat-roll system, so there is less chance of toner smearing on the copy or print.

Example: Model G071

The illustration to the right shows the fusing unit of model G071. The key components are the heating roller, hot roller [C], pressure roller [D], and fusing belt. The heating and pressure rollers each have a fusing lamp. (770W and 350W respectively) However, the hot roller has no fusing lamp; instead, it is heated by the belt. Thermistors [E] control the

[C]

[D] [E]

[A] [F]

[B]



temperature of the rollers. A small idle roller [F] increases the nip width between the belt and the pressure roller, so more of the paper is heated at any one time. At the start of the fusing nip (area of contact between the pressure roller and the fusing belt), toner begins melting. When the paper comes between the hot and pressure rollers, the toner has already melted, and at that point it is pressed into the fibers of the paper.



Fusing Pressure Mechanism

The pressure mechanism is a critical part of the fusingunit. The fusing pressure must be sufficient to form aproper nip band (see previous page). The pressuremust also be even so that the paper feeds smoothlybetween the rollers without creasing or wrinkling.

The most common method of applying fusing pressureis with a spring. The illustration to the right (model A219)is a typical example. The fusing pressure can beadjusted by changing the point where the spring isattached. In this case fusing pressure is appliedconstantly.

Some copiers, especially higher-speed models, usescrews to apply fusing pressure. The mechanism shownin the lower picture (model A171) allows precisepressure adjustment using adjustment screws [A].

This model allows the user to release fusing pressure tohelp clear paper jams. This is done by the upperpressure lever [B] and lower pressure lever [C] whichare lifted up by the fusing unit release lever [D] via thepressure cam [E].

A219R538.wmf

A171D641.pcx

[B]

[C][E]

[D] [A]



Oil Supply

Silicone oil is applied to the hot roller to help prevent toner and paper from sticking to the hot roller, toreduce paper curl, improve hot roller durability, and to help in roller cleaning. With such benefits youwould expect that all photocopiers would have an oil supply system. This used to be the case.However, advances in design and composition of fusing rollers and toner have made oil applicationless important. Recently, many products do not have an oil supply mechanism. But, oil supplysystems are generally used in products that have a critical fusing function—typically high-speed orcolor machines.




The A166 series (Azalea) has a rather complex oilsupply system.

A small pump with a one-way valve moves the oilfrom the oil tank [A] to the oil supply pad [B]. Theoil pump lever [C] alternately presses and releasesthe rubber tube [D] between two one-way valves[E] as the oil cam [F] turns.

To keep oil use to at a minimum, two oil supplyrollers are used. One is in contact with the oilsupply pad and the other contacts the hot roller.The oil supply pad applies oil to the first oil supplyroller [G]. If there is not enough oil on the hot roller,friction between the second oil supply roller [H] andhot roller increases, and the oil supply roller turns.As it turns the second oil supply roller supplies oil tothe hot roller and picks up more oil from the first oilsupply roller.

Excess oil flows out through the hole [I] in thebottom of the oil sump and returns to the oil tank.

A166D637.wmf

[B]

[G]

[H]

A166D636.wmf

[C]

[D]

[E]

[F]

[I]

[A]

[B]



Cleaning

The hot roller has a non-stick coating and toner is formulatedto help prevent it from sticking to the hot roller; but even withthat, a small amount of toner still sticks to the hot roller. Thistoner is removed by a cleaning pad or a cleaning roller. Inmany machines silicone oil is applied to the hot roller. Thesilicone oil acts as a lubricant and helps to prevent toner fromsticking. (See the preceding section.)

Cleaning PadFusing roller cleaning pads are not as common now as in thepast, but they are still commonly used in low speed copiersand fax machines. The upper illustration shows the positionof the cleaning pad [A] in the fusing unit of model G026.

The chief advantages of a cleaning pad are low cost andsimple design.

The major drawback of the cleaning pad is that it must bereplaced periodically. To reduce service cost, recentlymachines have been designed with user replaceablecleaning pads. The illustration to the right showsreplacement of the fusing cleaning pad in model H523.

FX10fcln.pcx

[B]

G025D522.WMF

[A]



Cleaning RollerThe cleaning roller is the most common way ofremoving toner and paper dust from the fusing rollers.The principle of operation is simple. Any toner thatsticks to the hot roller preferentially transfers to thepressure roller. The pressure roller may also pick upsome toner from the reverse side of the paper (fromduplex copies). The toner and paper dust transfer tothe cleaning roller due to adhesion. The tonerpreferentially sticks to the cleaning roller because it ismade of metal.

Example: Model A133

The cleaning roller [A] is always in contact with thepressure roller [B]. It collects toner and paper dustadhering to the surface of the pressure roller. This isbecause the cleaning roller is made of metal andcollects any adhering matter more easily than thepressure roller (which has a Teflon coating).

A133d603.wmf

A133d575.wmf

[B]

[A]



Fusing Temperature Control

The CPU uses a thermistor to sense the temperature of the hot roller surface. Based on the inputfrom the thermistor, it turns the fusing lamp on and off to keep the hot roller surface at the targettemperature. Due to differences in copy rate, toner composition, and fusing unit construction, thetarget temperature varies from machine to machine but is generally in the 180°C to 200°C range.The target temperature may also change depending on the machine condition. For exampletemperature is controlled in model A219 as shown in the following diagram.

A219D533.wmf



The following table explains the conditions shown by the above diagram.

Machine Condition Fusing LampON/OFF Threshold

Remarks

Ready 165°C: 120 Vmachines

172°C: 230 Vmachines

—

After the main switch isturned on, until one minutehas passed after the hotroller temperature reachesthe Ready condition.

190°C After the fusing temperaturereaches the readytemperature the fusing lampis kept on until it reaches190°C.

After the above time period,the copier enters the energysaver mode.



When the Print key ispressed, the red indicatorblinks and copying starts afterthe fusing temperaturereaches the Ready condition.

During copying 190°C —



Fusing Lamp Control CircuitThe diagram (model A219) isa typical fusing lamp controlcircuit. While circuit detailsvary depending on powerrequirements and machinedesign, certain features arecommon to most machines.

First, all machines monitor thefusing temperature using athermistor. The thermistor iseither in contact with the hotroller or positioned very closeto it. Also, a zero cross signalgenerated from the ac powersupply is used to generate thetrigger pulse and control theapplied power accurately.

Since the fusing lamp is a high temperature heat source, safety is an important consideration.Interlock switches cut power to the fusing circuit whenever a cover is opened. Also, all machineshave an overheat protection circuit which automatically cuts off the fusing power and stops machineoperation if the temperature detected by the thermistor gets too high. Backup overheat protection is

CN113-1CN113-25 V

CN101-324 V

CN101-4

CN207-7

CN207-6

PC2

T205

T206

T204

T207

T208

T203

InterlockSwitch

Main Switch

Fusing Lamp

FusingThermistor

AC Power Source

FU1

AC Drive/DC PowerSupply Board

Main Board

Trigger Pulse24 V0 V

T202 T201

RY1 L4

C20

230 V machines only

A219D537.wmf

TF



provided by a thermofuse (TF). Even if the thermistor overheat protection fails, the thermofuse opensif the heat gets excessive, removing power from the fusing lamp.

On/Off Control

When the main switch is turned on, the main board starts to output a trigger pulse, which has thesame timing as the zero cross signal, to the ac power supply circuit. This trigger pulse allowsmaximum ac power to be applied to the fusing lamp. When the operating temperature is reached, theCPU stops outputting the trigger pulse (the trigger stays HIGH) and the fusing lamp turns off.

Phase Control

Normally, the voltage applied to the lamp is the full duty cycle of the ac waveform. However, manymachines have an alternate method of fusing power control called phase control. Generally, phasecontrol is used only if the customer has a problem with electrical noise or interference on the powerline. Phase control is selected using a service program.



Example: Model A219

The main board sends the fusing lamp triggerpulse (LOW active) to the ac drive/dc power supplyboard, which provides ac power to the fusing lampat the falling edge of each trigger pulse. Thetrigger pulse goes HIGH when the main boardreceives the zero cross signal.

The amount of time that power is applied to thefusing lamp depends on the temperature of the hotroller.

The trigger pulse (LOW part) is wider [C1] andpower is supplied for longer [D1] when the hotroller temperature is lower. It is narrower [C2] andpower is supplied for a shorter time [D2] when thehot roller is near the operating temperature.

A219D537.wmf


DDiiggiittaall PPrroocceesssseess Digital Scanning Basic concepts

Analog Machines Example: Model A219

An exposure lamp illuminates the original. Mirrors reflect light from the original directly onto the photoconductor. This light writes a latent image on the photoconductor. This image is then developed with toner and transferred to the copy paper.

a219d507.wmf

Digital Scanning Image Processing Printer Engines Printer Interface Basics


Digital Processes Digital Scanning

Digital MachinesExample: Model A193

The big difference with scanners in digital machines is that the light reflected from the original doesnot pass directly to the photoconductor.

The light is reflected onto a light-sensitive element, such as a CCD (Charge Coupled Device). Thisdevice converts the light into an analog electrical signal. Circuits inside the machine convert thissignal into a digital signal. This signal then passes to a laser diode, which emits a laser beam to writea latent image on the photoconductor.

So, in a digital machine, there is a lot of electronics between the light reflected off the original and thelight arriving at the photoconductor.

a193v505.wmf



Digital SignalsDigital signals consist of binary code. Whenscanning an original, binary code is used torepresent the brightness of each pixel of theimage.

In the most simple of systems, there are only twovalues for each pixel: 0 and 1, for black andwhite.

However, most machines use 4 or 8 bits.

In a four-bit system, there are 16 possible valuesfor each pixel. This allows black, white, and 14shades of grey in between.

Similarly, in an eight-bit system, there are 256possible values for each pixel. This allows black,white, and 254 shades of grey in between (seethe diagram).

digdata.wmf



Digital Images

OverviewAnalog machines transfer an optical image ofthe original directly onto the photoconductor.

Digital machines break the image up into smalldots, known as picture elements, or pixels forshort.

The example shows the image that the machinebuilds up of a fax machine test chart.

This may seem to be a rather inaccuraterepresentation. However, digital signals can bemanipulated to enhance the image and createspecial effects.

Also, digital images can be used immediately, orstored for later use (see Image Files).The size of the pixels (smaller pixels yieldgreater ‘resolution’) depends on several factorsrelated to the scanner and printer hardware.(The software may also be set up to alter theresolution in various ways, but we shall look athardware in this section.)

testchrt.wmf



Scanner ResolutionThere are two points to consider: the image detector (typically a CCD) and the scanner motor

CCD

The CCD (charge-coupled device) is a line ofphotosensitive elements. The output of the CCDrepresents one line across the page. Eachelement of the CCD generates one pictureelement of the line. So the CCD resolution is theresolution of the scanner across the page (this isalso known as the ‘main scan’). The moreelements there are per unit length, the finer theresolution. Typical CCDs have 200 or 400elements per inch (or, for Group 3 fax machinesoperating in metric units, 8 or 16 elements permm).

ccdpixel.wmf

CCD

Elements



Scanner or ADF Motor

Example: Model A229, ADF mode

The scanner or ADF motor is normally astepper motor. The distance fed by eachstep of the motor determines theresolution of the scan down the page(also known as the ‘sub scan’ direction).Typical resolutions are 200, 300, or 400lines per inch (or for Group 3 faxmachines, 3.85, 7.7, or 15.4 lines permm).

To scan an image, the CCD scans a line.Then the scanner motor feeds the pageone line, and the CCD scans anotherline. This is repeated until the entire pagehas been scanned.

a229d651.wmf

Main scan

Sub scan



Scanner OutputEach element of the CCD generates a voltagewhich represents the intensity of the light reflectedonto it from the document. The signals from all theelements are output in sequence, to generate ananalog signal that represents the line that iscurrently being scanned.

The upper diagram on the right shows an exampleof output from a line on a page which is all whiteexcept for a black shape on the left of the page.

After the line has been scanned, the scannermoves the document forward one scan line widthto move the next scan line into position. Then, theCCD reads the next scan line.

The bottom diagram shows the next line beingscanned.

White

Black

CCD

CCDOutput

SCANLINE

scanlin1

White

Black

CCD

CCDOutput

SCANLINE

scanlin2.wmf



The signals from each consecutive scan line arestrung together end to end, and sent out as ananalog signal. The diagram opposite shows whatthe video signal would be like for the twoconsecutive scan lines shown in the previous twodiagrams.

The output is then processed as described in ImageProcessing.

The next few pages show the basics about how the processed data is printed.

White

Black

Onescan line One scan line Etc

VIDEOSIGNAL

ccdsig.wmf



Printer ResolutionThe output from the scanner is converted to a laser diode drive signal. The laser beam then writes alatent image of the original on the photoconductor. There are two points to consider: the laser beamas it arrives on the photoconductor, and the speed of the photoconductor.

Example: Model H006, using a master belt

Exposure of the photoconductor to the laser beamcreates the latent image.

To make the main scan, the laser beam movesacross the photoconductor. The resolution dependson the speed of the laser beam’s motion across thephotoconductor and on the frequency of the laserbeam on/off switching clock.

To make the sub scan, the photoconductor rotates.The resolution depends on the speed that thephotoconductor rotates.

In multifunctional machines, laser engines have tobe able to print at a range of resolutions: 400 dpifor copying and Group 4 fax, 600 dpi for printing,and 16 x 15.4 dots per mm (391.2 x 406.4 dpi) forGroup 3 fax.

For full details of the laser optic system, see the Laser Printing section.

laserprt.wmf

Main Scan (LaserBeam Motion)

Sub Scan(Photoconductor Rotation)



The cross section of the beam on the master(i.e., the size of each printed dot) varies frommodel to model; it is roughly circular.

In the example shown, from a Group 3 faxmachine, the diameter is about 80 µm. Thismeans that the printed dots overlap eachother slightly, as shown in the diagram. 80 µmis about 12 dots per mm, and 90 µm is about11 dots per mm.

However, the printer resolution is 16 x 15.4 dots per mm for a Group 3 fax machine. The dots arelarger than this resolution, so they overlap. This results in a better image than if there were nooverlap.

Generally, the laser beam switches off between pixels, even between black pixels.

Note that, unlike the scanner/ADF motors, the motor that drives the photoconductor is normally a dcmotor, not a stepper motor. Therefore, in theory, the main scan lines written across thephotoconductor will be sloping very slightly.

For more details, see the Laser Printing section.

laserdot.wmf



Printer OutputDuring the copy cycle, thephotoconductor is charged to about -900 V (see Photocopying Processes –Charge). The laser beam writes alatent image on the photoconductor.

The charge on irradiated areas dropssignificantly, typically to between 0and -100 V. (Voltage values differfrom model to model.)

The area of the photoconductor that isirradiated depends on whether the’write to white’ or ’write to black’method is being used.

ORIGINAL WRITE TO WHITE WRITE TO BLACK

Irradiated Areaslaserwrt.wmf


Digital Processes Image Processing

Image Processing

Introduction

This section describes how digital machines convert the image from a scanned original into digitaldata. This section also describes techniques for processing the digital data, so that the printout is asclose to the original as possible. For example, techniques used to process a business letter will bedifferent from those used to process an original containing photographs.

Each model implements these techniques in different ways, and some models do not implement allthe techniques. In addition, the order of steps may be slightly different from that presented here. Thissection will provide a general description, with examples from various models.

The techniques used by black-and-white machines and color machines are different. Also, black-and-white machines can use two different types of image sensor in the scanner. As a result, thissection will be divided into three sub-sections, as follows.

• Black and White Machines - CCD SystemsThis section describes black-and-white models that use a CCD (Charge Coupled Device). This isthe standard method for mainstream digital machines.

• Black and White Machines - CIS SystemsThis section describes black-and-white models that use a CIS (Contact Image Sensor). This typeof system is often used in lower-priced models.

• Color MachinesThis section describes image processing for color machines. These use a CCD of a differenttype, to generate data for the three primary colors.



Black and White CCD Systems

Overview

The diagram shows a typical example of an image processing circuit.

An exposure lamp illuminates the original. Light reflected from the original is reflected through a lensto the CCD.

LDDriver

IPUDrum

SBICULDDR

SBU

CC

D

HDDGA1

LDController

(GAVD)

LDDriver

GA2

MemoryControl ICs

a229d578 wmf



The CCD generates an analog signal from the light. The voltage of the signal varies with the intensityof the light. The CCD is mounted on a board called the SBU (Sensor Board Unit). The analog outputfrom the CCD must be converted to a digital signal. In the above example, the analog-to-digitalconversion circuits are on the SBU board.

The digital signal is then processed, using large-scale integrated circuits, like the IPU (ImageProcessing Unit) in the above example. Some of the processes require enough working memory tostore a page of image data. The data may then be stored temporarily on a hard disk until it is time forprinting. The data then passes to the laser diode controller and laser diode driver.

After data processing, each pixel scanned from the original is represented by a number of bits (eightis a typical number), or only one bit (0: White, 1: Black), depending on the type of digital processingused. Also, the image may be enlarged or reduced. In this case, pixels will be deleted or artificiallycreated to make the new image.

Scanner Lamps and the Shading Plate

Fluorescent lamp: The ends of the lamp are not so bright as the center. To compensate for this, thelight reflected from the original goes through a shading plate before it reaches the CCD. The shadingplate allows more light to pass through from the ends of the lamp than from the center.

Xenon lamp: If a xenon lamp is used, the difference in brightness is smaller than with a conventionalfluorescent lamp, but this problem still exists.

LED array: This is a strip of photodiodes. As all the diodes are equally bright, a shading plate is notneeded.



CCDA CCD converts the light reflected from the original into an analog signal.

The CCD (Charge Coupled Device) consists of a row of photosensitiveelements. The circuit of each element in the CCD is shown at the right. Lighthitting the photodiode charges up a capacitor. The brighter the light, the morecharge goes into the capacitor. There is more about CCDs in the StandardComponents chapter.

The CCD has between 2,500 and 5,000 of these elements, depending on themaximum scanning width and number of pixels per unit length (i.e., theresolution across the page). A typical CCD in a high-end digital copier has5,000 elements, at a resolution of 400 dpi (15.7 dots/mm).

A CCD in a G3 fax machine may have a resolution of 8 or 16 pixels/mm, to match ITU-T standards.However, as many machines are now multi-functional, such machines often employ a dpi-basedCCD and convert the signal to mm format when sending a Group 3 fax.

The voltage from each element depends on the intensity of the light reflected from the original ontothe element; the intensity of the light depends on the darkness of the area of the document it wasreflected from.

These charges are output from the CCD one after another, to make an analog video signal. Then thescanner moves to the next line of the original, and the CCD scans the next line.

The CCD scans the original one line at a time, and outputs an analog signal for each line.

c222d580.wmf



Analog Signal Processing

Overview

CCD

Z/C

Z/C

Z/C

0 Ref

1 Ref

Black Level

White Level

Odd

Even

Peak Hold

Automatic GainControl (AGC)Signal Combining

Auto Shading Circuits

ZeroingBlackLevel

Feedback

Feedback Feedback

Feedback

Analog Signal Input

Digital SignalOutput

To DigitalProcessing

Circuits

A/DConverter

ana-ads.wmf



This section describes:

• How the raw CCD output is prepared for conversion to digital data

• How the corrected CCD output is converted to digital data

The previous illustration shows the various steps and processes involved in preparing and convertingthe analog signal. The following table quickly summarizes each step.

CCD output How the raw data is output from the CCD.

Auto shading A key part of analog signal processing. It affectsmost of the other steps and processes.

Zeroing Black level correction prior to signal combination.

Signal combining Merging of the odd and even picture elements.

Automatic gain control Signal amplification and white level correction.

Black level Black level correction after automatic gain control.

Auto image density Removes background from the scanned image

Peak hold Holds the peak white value for A/D conversion.

A/D conversion Conversion of the analog signal to a digital signal.



CCD Output

This diagram shows the CCD and its data outputlines as a simplified block diagram.

There are two outputs from the CCD. One is for odd-numbered pixels, and the other is for even-numberedpixels. A clock switches the output for each pixel ontothe odd or even output line alternately.

Having two outputs speeds up the image processing.CCDs in older models (mainly fax machines) only hadone output line.

The two outputs are amplified before entering theanalog signal processing circuits.

Details about the amplification of the raw CCD outputsignal are given in section 8 (Components).

Reflected

light

Even

Amplifier

Switching clock

CCD

Photoelectricconversion

Signalamplification

ODD

ccdblock.wmf



Auto Shading

Auto shading corrects errors caused by variations in the signal level for each pixel. Both the blacklevel and the white level are corrected.

a229d645.wmfVariations in theBlack Level

Variations in theWhite Level



1) White Level Correction

The video signal information for each pixel obtained during image scanning is corrected by the imageprocessing circuits.

The data has to be corrected for variations in white level across the page. These variations arecaused by the following factors.

• Loss of brightness at the ends of the exposure lamp with age or temperature (noticeable withfluorescent lamps and xenon lamps), or any bright and dull spots on the lamp

• Less brightness at the edges of the lens

• Variations in response among the CCD elements

• Distortions in the light path, such as differences in reflectivity across the scanner mirrors.

To correct for this, the machine scans a white plate before scanning each original. (This white plateis normally under the scanner cover or under the left scale of the exposure glass.) The white plate isuniform in color and in reflection.

The output from each element of the CCD isconverted to digital and passed to a memory in theauto shading circuit. The waveform of the whiteplaten cover from the CCD is not uniform, becauseof the factors mentioned above.

c222d584.wmf



In some models, there is a protection circuit which limits the white peak voltage. This is to preventdark printouts resulting from an abnormally high reference voltage caused by strong light intrudinginto the scanner.

In models that have a built in ADF, continuous scanning of large originals can cause the scanner toheat up, which affects the CCD’s response. Also, continuous exposure to light affects the CCD.Therefore, the white plate is scanned every 30 s to recalibrate the white level (it is done betweenoriginals; scanning is not interrupted).

After auto shading, the machine scans the page. The machine then uses the white waveform storedin the auto shading memory to correct the data. This is known as Automatic Gain Control (AGC). It isdescribed later.



2) Black Level Correction

Method 1: Dummy Pixels

This zeroes the black level for eachscanned line of data while scanning theoriginal. To get the current black level, theCPU reads the dummy data elements atone end of the CCD signal (some pixels atthe end are blacked off), and takes anaverage of the voltages read from theseelements. Then, the CPU deletes the blacklevel value from each image pixel.

This corrects the video signal for changes in response to the dummy black pixels as time passes.

The black level is stored in the auto shading circuits (as a charge inside a capacitor, for example).

Method 2: Black Level Waveform

In some older models, the black level is done for every original, by shutting off the exposure lampand reading a black level waveform across the page. This is stored in memory in the auto shadingcircuits in a similar way to that described earlier for the white level.

Method 3: Fixed Reference Voltage

Some models correct the black level using a standard reference voltage for the black reference(about 1.5 Volts)

1 line

(V)

Output Before Correction

Video Signal

Output

(V)

1 line

After Correction

Video Signal

0 0

blk-lvl.wmf



When the machine scans the white plate before scanning the original, the odd and even pixel signalsare combined. The resulting signal is converted to digital in the A/D converter, and stored in thememory in the auto shading circuits.

The auto shading circuits are normally inside the digital processing circuits, and signals from thisfeed back into the analog circuits when needed.

The black level goes to the auto shading circuit every line during scanning.

CCD

Z/C

Z/C

Z/C

A/DConverter

0 Ref

1 Ref

Black Level

White Level

Odd

Even



ZeroingBlackLevel

Fixed VoltageExample: 2.5 V

Analog Signal Input

Digital SignalOutputStraight

Through

StraightThrough

StraightThrough

Every line

From white plate,before each page

shadcct .wmf



Peak white can be detected every scan line too - this is Auto Image Density mode (also known asADS mode). This is described later in this section.

In the above diagram, the high level reference is arbitrarily fixed at 2.5 V and the low level referenceat ground. In some cases, analog to digital (A/D) conversion is done using the peak value of thesignal for the high reference, and half of the peak value for the low reference.

Example: Model C211

The potential difference between the outputof each pixel and the 53% level of the peakhold is converted by an A/D converter into 4-bit data.

VPH

100%

53%

4bitsMemory

5,000 pixels

VT2100/2130/2150: 1.7VVT2300/2500: 1.4V

shading1.wmf



Zeroing

A zero clamp (Z/C) on each output adjuststhe black level reference. The black level forthe even pixels is adjusted to match theblack level from the odd pixels. Feedback ofthe black level from the auto shading circuitis used.

Signal Combining

A multiplexer merges the analog signals forodd and even pixels from the CCD.

In very high speed digital machines, thesignals are not combined until the digitalprocessing circuits. These machines haveseparate analog processing circuits for oddand even pixels.

CCD

Z/C

Z/C

Z/C

Black Level

White Level

Odd

Even



ZeroingBlackLevel

Feedback Feedback

Feedback

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1 3 5 49954997

4999

2 4 49964998

5000

1 2 3 4 49984999

5000

vid-comb.wmf



Automatic Gain Control (AGC)

The analog signal is amplified byoperational amplifiers in the AGC circuit.

When the original is scanned, the whitelevel waveform is read back in from the autoshading memory. The AGC circuit uses thewhite level signal to correct the video datasignal.

In effect, each element of the scan line isamplified by an amount that depends on thevoltage of the same element in the whitelevel signal. An example is shown on thenext page

CCD

Z/C

Z/C

Z/C

Black Level

White Level

Odd

Even



ZeroingBlackLevel

Feedback Feedback

Feedback

ana-ads.wmf



For shading correction, the peak of the scanfrom the white plate is set to 1. Let us takean example, in which the level of the 500thelement of the white waveform is 0.8 (i.e.,not perfectly white).

Then, at a point during scanning, say thatelement 500 in the video signal has a valueof 0.6; it would be higher if there were noscanner irregularities.

So, element 500 in the video signal iscorrected as follows: 0.6/0.8 = 0.75.

Each element in each video signal scan lineis corrected in this way.

Also, if the platen cover is dirty, the values will be lower due to reduced reflection from the platencover. This means that the image data will be overcorrected, causing pale bands in the image.

0

0.8

1

500

Element 500

WhiteWaveformScanLine

0

0.6

Video ImageScanLine

500

shadcorr.wmf



Black Level

Before the data enters the A/D (analog-to-digital)converter, a zero clamp circuit again fixes theabsolute value of the black level using feedbackfrom the auto shading circuit.

Z/C

0 Ref

1 Ref

Black Level

White Level

Peak Hold



BlackLevel

Feedback

Feedback Feedback

Analog Signal Input

A/DConverter

ana-ads.wmf



Auto Image DensityIn some machines, this feature is called Original Background Correction.

Auto Image Density (ADS) mode corrects for variation in background density down the page, toprevent the background of an original from appearing on copies.

ADS mode detects the background level for the original, also known as the peak white level, andremoves this from the image, to make a white background. The machine must ensure that it detectswhite level from areas of the original that are free from image data. There are two methods, whichare explained on the next page.

When an original with a grey background is scanned, the density of the grey area becomes the peakwhite level density for that original. Therefore, the grey background will not appear on copies. Also, inmachines where peak level data is taken for each scan line, ADS corrects for any changes inbackground density down the page.

Unlike with analog copiers, the user can select a manual image density when in auto image densitymode, and the machine will use both the manual and auto settings when processing the original.This is useful when making copies of an original that has light image density with background; ADremoves the background, and if the user selected a dark manual image density setting, the imagewill be brought out more clearly in the copy.



Method 1: Scanned from a narrow strip near therear scale (Example: Model A229)

The copier scans the auto image density detectionarea [A]. This corresponds to a narrow strip at oneend of the main scan line, as shown in thediagram. As the scanner scans down the page, themachine detects the peak white level for each scanline, within this narrow strip only.

Method 2: Scanned from a narrow strip at thecenter of the leading edge (Example: C211series)

In this machine, the original is placed at the centerof the original feed path, and not at one side like inthe A229. Therefore, the peak level is read from the central 64 mm at the leading edge of theoriginal.

One problem with this method is that, since scanning starts before the light intensity from thefluorescent lamp stabilizes, the light intensity tends to increase for a little while. The voltage from theCCD increases until the light intensity stabilizes. As a result, lighter image densities may not appearon prints after the light stabilizes. To prevent this, the peak voltage is changed when a higher (whiter)image signal is detected. If the peak voltage changes regardless of the output value, like in the A229,there is a chance of mistaking grey areas in the center of the image for peak white.

75mm

15mm

0.5mm

Sub scan directiona229d581.wmf

[A]



The peak hold circuit holds the peak white level.

From this peak white level, the machine determinesthe white reference value for A/D conversion.

The white level from auto shading is fed back to theADS circuit to correct for fluctuations in the whitelevel across the page.

Z/C

0 Ref

1 Ref

Black Level

White Level

Peak Hold



BlackLevel

Feedback

Feedback Feedback

Analog Signal Input

A/DConverter

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A/D Conversion

The A/D converter converts the analog signal to digital.

In a typical machine, the resulting digital signal has eight bits. This means that each pixel can haveone of 256 values.

However, before this can be done, the A/D converter must be supplied with reference voltages thatdetermine the black and white limits.

To do this, the A/D converter is supplied with a blackreference voltage (0 Ref). For example, the inputcould be held to ground. This fixes the lowest of the256 levels – any pixel with the same voltage as theblack level will become black.

Also, the highest of the 256 values is fixed with awhite reference voltage (1 Ref).

When the analog signal is digitised, 0 Ref and 1 Refwill serve as references for black and white, and the256 levels of the grey scale will be distributedbetween these two levels.

If ADS is not being used, the white reference (1 ref inthe diagram) is held to a fixed voltage.

A/DConverter

0 Ref

1 Ref

Fixed VoltageExample: 2.5 V

Analog Signal Input

Digital Signal Output

To Digital ProcessingCircuits

ananoads.wmf



If ADS is being used, the white referencevoltage depends on the output of the peakhold circuit.

The A/D converter divides the range between the black and white reference voltage into 256 levelsand digitizes the analog signal based on these levels. These 256 levels are known as grayscales.

The low reference voltage terminal stays constant. Only the high reference terminal voltage varies.

Z/C

0 Ref

1 Ref

Black Level

White Level

Peak Hold



BlackLevel

Feedback

Feedback Feedback

Analog Signal Input

A/DConverter

ana-ads.wmf



Example: Model A099

In this example, the signal has beeninverted so that digital 0 is white and1 (0 Volts) is black.

The white level varies between 1.7and 2.9 V, depending on thefeedback from the peak hold circuitfor ADS. (If ADS was not being used,the white level would remain fixed.)

The A/D converter divides up therange from black to the current whitelevel into 256 levels.

The grey scale is based on the peakwhite level. The right side of thediagram shows how the range isdivided up if the white level is 1.7 V.If the white level was 2.9 V, thespacing would be wider.

If the voltage for a pixel is between level 2 and level 3, this is converted into a digital value of11111101.

Pure black (above level 255) becomes 00000000. Pure white (below level 1) becomes 11111111.

1.7V

2.9 V

25600000000............................

411111100............................

311111101............................

211111110............................

111111111............................

0V

25600000000...........................

256 levels calculated

Analog Digital

0RefRange

as follows:

D= Vin x0Ref256

(Dis the Digital data)

White

Black

00000001............................255

adcon.wmf



Digital Signal Processing

OverviewThis section explains how the raw digital data from the A/D converter is processed to produce afaithful image of the original.

Digital fax machines, scanners, printers, and copiers use a wide range of digital image processingtools. The processes used are different in every machine, and so is the order in which they are done.Because of this, a comprehensive description is impossible. However, representative examples willbe given. Many of the processes are proprietary, and in these cases, details cannot be given.

Digital processes can be broadly classified into the following types.

! Preliminary Image Enhancement: These processes prepare the data for processing by correctingthe data for scanner characteristics, and removing unwanted data such as dots in thebackground.

• Scanner Gamma Correction

• Background Erase

• Independent Dot Erase

• Text/Image Separation



! Filtering: These processes enhance the data to suit the original mode (text or photo) selected bythe user.

• MTF (Modulation Transfer Function)

• Photo mode Smoothing

! Magnification and Reduction: This enlarges and reduces the data, depending on the reproductionratio selected by the user, or the paper size in the receiving fax terminal.

! Gradation Processing: The gradation processing methods used generally depend on the originaltype setting (text, photo, etc) selected by the user.

• Grayscale Processing

• Binary Picture Processing

• Dithering

• Error Diffusion

! Editing and Merging

Using a memory work area, digital data can be manipulated to produce various effects, such ascombining several images onto one copy.

Also, multiple originals can be scanned into memory and several copies can be printed, alreadysorted, onto a single output tray. This is sometimes called electronic sorting. This feature allowslow-volume sorted output without needing all the extra hardware.



Another benefit of digital processing with memory storage is faster duplex copying throughput,using a feature known as 'interleaving'. This feature uses a duplex tray with a one-page capacity,stores multiple originals in memory, and outputs the data in the order that is suitable for the fastestprinting. This order is not necessarily the order in which the pages were scanned. This is coveredmore fully in the Paper Handling section (Interleave Duplexing).

The main benefits for most users are that a job with multiple originals can be scanned just onceand stored in memory, then printed many times from memory without having to scan again. Also,printer jams can be recovered without having to scan the original again.

• Merging

• Make-up Mode

• Image Rotation

• Combining Images

! Final Image Enhancement

• Erasure of Irregular Dots

• Line Width Correction

• Edge Detection

• Sub-scan Resolution Conversion

• Inch-mm Conversion



Scanner Gamma Correction

Scanner gamma correction corrects the data to account for thecharacteristics of the scanner (e.g., CCD response, scanneroptics). This ensures that the various shades in the grey scalefrom black to white on the copy match those on the original .

The relationship between original image density and analogcircuit output should be linear as shown in the upper diagram.However, in reality, it is more like that shown in the lowerdiagram.

Gamma correction corrects the datafor this deviation, as shown by thearrows in the lower diagram.

Scangam1.wmf



In some machines, the gamma curve can be changed with a service mode.

Also, some machines automatically adjust the gamma curve depending on the image density settingselected by the user.

Example 1: Model C222

If the user selects ‘dark’ mode, the ‘dark image’ gamma curve is used and the output is darker.

C222D588.wmf

Dark imagesetting

Normal imagesetting



Example 2: Model C210

In this machine, there are four different imagedensity settings, as shown (Darker 2, Darker 1,Normal, Lighter), There is an additionaladjustment for tone. Using these, the user canemphasize better reproduction of pale or darktones.

For example, if the user selects ‘dark tone’ mode(solid lines), the gamma curves change so that theoutput changes rapidly for small changes in inputat the dark end of the scale. (The dotted linesshow the curves for normal tone.) This causesshades of grey at the dark end of the scale to bereproduced.

There is also a printer gamma correction, to adjustthe data for printer characteristics. This isdiscussed in the Laser Exposure section.

Normal Tone

Normal

Darker 1

Darker 2

Lighter

na2gamma.wmfInput

Output

Dark Tone Mode



Background Erase

Usually, dirty background is erased using Auto Image Density (ADS). However, sometimes, dirtybackground areas will still appear. These can be erased by Background Erase.

If any low image density data which is lower than a threshold level remains after auto shading, thisdata will be treated as '0', which is equal to 'White'.

By adjusting the threshold to a larger value, darker backgrounds can be eliminated.

Example: Model A229

If there is a sudden cutoff at the threshold,sudden changes in the data around the thresholdlevel area can cause errors during the MTFprocess. So, in the example shown, the imagedensity does not cut off at the threshold [A], butgets paler more rapidly than usual, until at acertain point [B] it becomes white.

0 255

255

[A][B]A229D591.WMF

Output

Input



Independent Dot Erase

This feature removes isolated black pixels from the image. It is normally not used in photo mode, toavoid deleting details from images.


The software compares each pixel (C in thediagram above left) with the pixels around theedges of the surrounding 3 x 5 area. If the sumof the pixels at the edges is smaller than thethreshold value, the object pixel is changed to0 (white) or reduced in density to an averageof the pixels around the edge, depending onan SP mode setting.

The threshold can also be adjusted.

In the example shown to the right, if the pixel isbelow the threshold value, it is either erased,or reduced to 3 (the average of the pixelsaround the edge, which is 37 divided by 12).

A1

A6

A8 A9 A10 A11 A12

A7

A5A4A3A2

C

0

0

0 0 0 0 0

0

07300

90

Original image

3 x 5 area Image data

A231D528.WMF



Text/Image Separation

When the user selects Text/Photo mode, the machine processes text areas and image areasdifferently.

Some machines have only a simple text/image separation as part of the error diffusion process(described later), whereas others have a more sophisticated algorithm (described in this section).

Note that for some machines, “Letter mode” is used to refer to originals containing text. "Letter"refers to a type of image data, not Letter size paper or "correspondence". It means text and/or lineart.

Method 1: Edge and dot screen area detection

Generally, text areas have strong contrast between theimage and the background. In photo areas (dot screenareas), there is a less extreme range of contrast, andmid-range grey areas are common. By using thesecharacteristics and the following separation methods, theoriginal image is separated into text and photo areas.

1. Edge detection

Edges of letters and parts of images are detected by checking for strong contrast, continuity of blackpixels, and continuity of white pixels around the black pixels.

EdgeDetermination

Dot ScreenDetermination

FinalEvaluation

Text/Photo Separation

a229d625.wmf



2. Photo area (dot screen) detection

Each pixel is tested to see if it is in a dot screen area by comparing with nearby pixels.

Example: Model A229

The page is divided into 4 x 4 blocks ofpixels. Each block is placed at the centerof a 5 x 3 array of these blocks, andbecomes either text or photo, dependingon the other blocks in the 5 x 3 area .

If the number of dot screen blocks in the 5x 3 area exceeds a threshold, the centralblock is determined to be an image area.(The threshold is 2: if two or more of theblocks in the 5 x 3 area are dot screen,areas then all the pixels in the centralblock are determined to be in an image area.)

DotScreen

DotScreen

DotScreen

DotScreen

DotScreen

DotScreen

Determined to be Photo Determined to be Text

DotScreen

a229d640.wmf



Final Evaluation

The machine decides whether each pixel is in a text or image area by looking at the results of theedge and dot screen detection processes.

Example: Model A229

Dot Screen Edge Final EvaluationNo No PhotoNo Yes TextYes No PhotoYes Yes Photo

Text and image areas can then be processed differently.

Example: Model A133

The image data is treated by MTF and by smoothingsimultaneously. However, the result of the final evaluationcontrols a selector switch. For a text area pixel, the outputfrom the MTF selector is selected. For an image area pixel,the output from the smoothing circuit is selected.

MTF Correction

GA3

Smoothing

Selector Switch

Edge Detection

Dot ScreenDetection

Final Evaluation

Filter

Auto Text/Photo

a133d549.wmf



Method 2: Comparison of adjacent pixels

Example: Model C226

In the Letter/Photo mode, the machine checks each pixel of theoriginal to see if the pixel is in a line area or in a photo area. Torecognize a line area in a photo original, the CPU does thefollowing calculation on the 6-bit pixel data.

x = | (c + f + i) - (a + d + g) |

y = | (g + h + i) - (a + b + c) |

If x or y is greater than 10, the machine recognizes that pixel eis in a letter area.

If the calculated number is 10 or less, the pixel is in a photo area.

In larger digital machines, this is a part of the error diffusion process, in addition to the maintext/image separation process described earlier.

c222d595.wmf



MTF (Modulation Transfer Function)

When the CCD converts the original image to electrical signals, the contrast is reduced. This isbecause neighboring black and white parts of the image influence each other as a result of lenscharacteristics. This symptom is typical when the width and spacing between black and white areasare narrow. MTF correction counters this symptom and emphasizes image detail.

Because of this, MTF is necessary for reproduction of details such as thin lines, points, and complexcharacters. Without MTF, such details may be lost, or only partly reproduced. Small dots and thinlines may be split up over more than one pixel. If the dot or line is small enough, the pixel output mayfall below the threshold required to register a black pixel, and it would not be printed.

Because MTF sharpens the image, it is normally not used with photo mode. However, MTF can beuseful in photo mode when putting more weight on improving the resolution when copying fromcontinuous tone originals. Also, in text/photo or photo mode, MTF can be combined with errordiffusion, which reduces differences in contrast.

The MTF algorithm generates a new value for the density of the element, using an algorithm thatuses the density values of neighboring pixels in the image.



Example: Model C223

Consider a small black point on a original asshown in the illustration (a) and (b). The 6-bitimage data (range 0 to 63) for this section of theoriginal is shown in (c). If the threshold level is32, all the pixels in this area will become single-bit white data and the image will not bereproduced (d).

The MTF correction prevents this image loss bymodifying the value of each pixel in thefollowing manner

The value of the target pixel is multiplied by 3.Then, 3/8 of the values of the pixels to the left and right, 1/8of the values of the pixels two steps to the left and right, and1/2 of the values of the pixels above and below aresubtracted from the new value of the target pixel. (If theresult is less than zero, then the pixel value is set to zero.)

-1/2

-1/23 -3/8-3/8-1/8 -1/8

c223d668.wmf

0 0 0 0

30

0 12 4 0

0 12 0

0 0 0 00 0 0 0

a) Section of original

c) Image data afterA/D conversion

d) Print without MTF correction(threshold level: 32)

b) Enlarged view of dot

C223d667.wmf



After the MTF correction is applied, the image data ofthe example is as shown in (e) and (f). The smallblack point is reproduced on the print.

The MTF algorithm can be strengthened by using highervalues in the calculation. See the example on the right.

In some machines, the MTF algorithm can be strengthened ineither the main scan direction, sub scan direction, or both atonce. For example, if the original has a lot of thin horizontallines, MTF can be strengthened in the sub scan direction topreserve these lines, without applying an excessive MTF inthe main scan direction.

A stronger MTF filter sharpens the image and leads to better reproduction of low image densityareas, but may lead to the occurrence of moiré in the image. Also, stains, scratches, and otherblemishes in the light path will appear on prints more easily.

-2

-26 -3/8-3/8-1/8 -1/8

C223d625.wmf

0 0 0

63

0 19.5 1.5

0 22.7

0 0 0

0 0 0

0

0

0

00

e) Image data afterMTF correction

f) Printout after MTF correction

c223d624.wmf



Photo mode smoothing

There are some different processes that use the name 'smoothing'. This section describes the imageenhancement process that is used in photo mode to make a softer image. The other types ofsmoothing act on the final data to remove jagged edges from the image. They will be described later.

Smoothing acts in a directly opposite way to MTF. It smoothes the contrast between adjacent pixels,giving better reproduction for photos. Because of this, it will not normally be used in text mode.



Example: Model A099

The smoothing algorithm is: the values of the 24pixels surrounding the object pixel and the object pixelare multiplied by the values in a 5x5 filter matrix. Thenthe new values are added together. The result is thendivided by 64 and rounded off to yield the new valueof the pixel. If this procedure is applied to theexample, the value of the pixel shown in the figurechanges from 18 to 17.

This algorithm is applied to all pixels. If the pixel is onthe edge of the image area, the missing data isassumed to be "0".

5

14 14 1814 14

14

14

14

18

14

14

14 18 19

18 19

18 19 20 21

18 19 20 21

185

17

1 2 2 2 1

2 4 4 4 2

2 4 4 4 2

2 4 4 4 2

1 2 2 2 1

Filter

Result

Image

: Object Pixel

(1/64)

c4smth-1.wmf



The filter can be changed using a service program to suit the typeof original.

Example: Model A099 again

1 2 2 2 11 4 4 4 12 4 8 4 2

1 4 4 4 11 2 2 2 1

1 2 2 2 12 4 4 4 22 4 4 4 2

2 4 4 4 21 2 2 2 1

1 1 1 1 11 1 1 1 11 1 1 1 1

1 1 1 1 11 1 1 1 1

c4smth-2.wmf

High-contrastoriginals

Low-contrastoriginals

Normaloriginals



Magnification and Reduction

Overview

If the user selects a magnification or reduction ratio at the operation panel before copying, the imagedata must be enlarged or reduced.

Also, fax machines have to reduce the data if the paper in the machine at the other end is not wideenough to print the message. The machine determines whether reduction is necessary by comparingthe received protocol signal with the document width sensor readings.

Sub Scan Direction

Method 1: Original transport speed

Example: Model A229

Reduction and enlargement in the sub scan direction are done by changing the scanner or ADFmotor speed.



Method 2: Deleting scan lines

The cpu does sub-scan reduction by cuttingout the 3rd and 7th scan lines in every 7scan lines (for A3 [11.7" x 16.5"] to A4 [8.3"x 11.7"]), or the 6th and 13th scan lines inevery 13 scan lines (for A3 [11.7" x 16.5"] toB4 [10.1" x 14.3"] and B4 [10.1" x 14.3"] toA4 [8.3" x 11.7"]).

This is only done by older fax machines.Recent models change the scanner motorspeed.

Example: A3 to A4 reduction

Main Scan Direction

Reduction and enlargement in the mainscan direction are handled by digital image processing circuits.

Method 1: Calculation of Imaginary Pixels

faxsubrd wmf



Example: Model A229

Scanning and laser writing are done at a fixed pitch (the CCD elements cannot be squeezed orexpanded). So, to reduce or enlarge an image, imaginary points are calculated that wouldcorrespond to a physical enlargement or reduction of the image. The correct image density is thencalculated for each of the imaginary points based on the image data of the nearest four true points.The calculated image data then becomes the new (reduced or enlarged) image data.



80 % Reduction

For example, data for 10 pixels in a main scan line are scanned by the CCD.

Those data are compressed into data for 8 pixels by the magnification processor. As a result, theimage is reduced to 80 %.

140 % Enlargement

Data for 10 pixels of a main scan line are expanded into data for 14 pixels. As a result the image isenlarged with a 140 % magnification ratio.

The calculation method is described below in more detail.



To reduce or enlarge an image, imaginarypoints are calculated that wouldcorrespond to a physical enlargement orreduction of the image. The imagedensity is then calculated for each of theimaginary points based on the imagedata of the nearest four true points. Thecalculated image data then becomes thenew (reduced or enlarged) image data.

Here is an example of how the calculationis done.

In the example on the right, the density atpoint 3’ (ρ3’) is calculated from the densities at points 2, 3, 4, and 5 (ρ2, ρ3, ρ4, and ρ5) as follows:

(ρ3') = ρ2 x h(1+r) + ρ3 x h(r) + ρ4 x h(1-r) + ρ5 x h(2-r)

h(1+r) + h(r) + h(1-r) + h(2-r)

The values of the weighting factors h(1+r), h(r), h(1-r),and h(2-r) depend on the value of r, as shown in thetable on the right. The set for the nearest value of r isused.

ScannedData Point

CalculatedData Point

2 3 4 5

1+r 2-r

2' 3' 4'

r 1-r

Mainscan.wmf

r h(1+r) h(r) h(1-r) h(2-r)0 0 1 0 0

0.25 - 0.25 1 0.375 - 0.1250.5 - 0.25 0.75 0.75 - 0.25

0.75 - 0.25 0.375 1 - 0.25



Method 2: Adding and Deleting Pixels

Another way to expand or shorten the main scan line is to add or delete pixels at regular intervals.

However, this method is not so flexible as method 1, because it does not allow the user to increaseor decrease the magnification in 1% steps (the ‘zoom’ feature).

Example: Model C226

Reduction Mode Discarded Pixels Remaining Pixels

100% 0 Pixels All Pixels93% 1/14 Pixels 13/14 Pixels (0.929)82% (A4 version) 3/11 Pixels 9/11 Pixels (0.818)75% (LT version) 1/4 Pixels 3/4 Pixels (0.75)71% (A4 version) 2/7 Pixels 5/7 Pixels (0.714)64% (LT version) 5/14 Pixels 9/14 Pixels (0.642)

71% reduction: 5 out of 7 pixels are used, 2 pixels arediscarded (see the diagram).

82% reduction: 9 out of 11 pixels are used, 2 pixels arediscarded.

93% reduction mode: 13 out of 14 pixels are used, 1 pixel isdiscarded.

In some machines, there is one exception to this rule. If the71red.wmf



pixel scheduled for deletion is darker than the pixel immediately to the right, the latter pixel is deletedinstead.

Enlarge Mode Added Pixels Pixel Ratio

115% (LT/A4 Version) 2 Pixels 15/13 Pixels (1.154)

122% (A4 Version) 3 Pixels 17/14 Pixels (1.214)

127% (LT Version) 3 Pixels 14/11 Pixels (1.273)

141% (LT/A4 Version) 9 Pixels 31/22 Pixels (1.409)

115% enlargement mode: Every 7th pixel and 13thpixel are doubled to produce 15 pixels from every13 pixels in the original (see the drawing).

122% enlargement mode: Every 5th, 10th, and 14thpixels are doubled to produce 17 pixels from every14 pixels in the original.

127% enlargement mode: Every 4th, 8th and 11thpixels are doubled to produce 14 pixels from every11 pixels in the original.

141% enlargement mode: Every 3rd, 5th, 8th, 10th,13th, 15th, 18th, 20th, and 22nd pixels are doubledto produce 31 pixels from every 22 pixels in theoriginal.

115enl.wmf



Some digital processes can cause moiré when used in conjunction with reduction or enlargement atcertain reproduction ratios.

Because of this, the order of some processes depends on the reproduction ratio.

Example: Model A229

64% reduction or less: Main Scan Reduction then Filtering (MTF or Smoothing)

65% reduction or higher: Filtering (MTF or Smoothing) then Main Scan Magnification/Reduction



Method 3: Laser Diode Pixel Width

Example: Model H523

The CPU controls the magnification ratio by changing the interval between pulses in the laser clocksignals. So, for example, the clock signal pulse interval for 200% enlargement is twice as long as theinterval for normal (100%) image reproduction. This makes each image pixel for 200% enlargementbecome twice as long as each pixel for normal image reproduction.



When using the ADF, the magnificationcircuit has to create a mirror image.This is because the main scan starts isat the other end of the scan line in ADFmode (as compared with platen mode).In platen mode, the original is placedface down on the exposure glass, andthe corner at [A] is at the start of themain scan. The scanner moves downthe page. In ADF mode, the ADF feedsthe leading edge of the original to theDF exposure glass, and the oppositetop corner of the original is at the mainscan start position.

To create the mirror image, the CPUstores the main scan line data in aLIFO (Last In First Out) memory fromthe last pixel. When loading the mainscan line data from the LIFO memory,the CPU loads the first pixel of the mainscan line.

A193D504.wmf



Moiré

When one pattern is imposed over anothersometimes they interfere with each otherand form a third pattern called a moirépattern. In our products, MTF processing isa major cause of moiré patterns.

The illustration shows one of the moirémechanisms. In this case, the pixel densityof the CCD is the same as the density ofthe regular lines on the original. However,the regular lines are slightly out of stepwith the CCD pixels. As a result, eachCCD pixel has a different value (as shownin the figure). Since the length of a CCD pixel is very short, the waveform from the CCD output lookslike the cross lines in the figure. The moiré pattern appears when prints are made from this signal.The moiré pattern typically appears when the CCD pixel density is a multiple of the density of theregular lines on the original.

CCD

CCDOutputData

OriginalImage

1.7 V

Data forone CCDelement

Waveform

C223d635.wmf



Grayscale Processing

Grayscale processing uses many shades of grey to reproduce continuous tone originals, such asthose containing photographs. A black and white photograph contains an unlimited number ofshades of grey, but digital copiers and printers can normally only output a few shades, normally 64 or256.

If grayscale processing is used, the digital image processing circuit outputs, to the memory or laserdiode driver, the result of all the previous enhancement and filtering processes, without any errordiffusion or dithering. The result is a multi-bit per pixel stream of digital data. For example, if there are256 shades of grey, there are eight bits per pixel.

Note that grayscale processing needs a lot of memory. At eight bits per pixel (256 shades of grey),an A4 or LT page needs about 14 megabytes, without compression.



Binary Picture Processing

In binary picture processing, the output data is one-bit only. There are no shades of grey. the outputis black or white only.

The multi-bit per pixel data stream has to bereduced to single-bit data. To do this, athreshold level is used. If a pixel has a valuethat is brighter than the threshold, it becomesa white pixel. If it is darker than the threshold,it becomes a black pixel.

The threshold can usually be adjusted, and itoften varies depending on modes selected atthe operation panel. The example on the rightshows how the threshold level affects theoutput.

If binary picture processing is used withdithering or error diffusion, then the thresholdlevel for each pixel will be different, asdescribed in later sections.

60

36

2420

Output

Density

Print

Original

Threshold Level: 24

60

2016

8

Density

Print

Threshold Level: 16

Original

Output

thresh.wmf



Dithering

This is used to reproduce originals with continuous tones, such as photographs on machines thatcannot output true grayscales. Dithering produces different shades of gray by making differentpatterns of black and white dots. There are no gray dots at all. Dithering is sometimes called half-toning, and the various shades of gray are called halftones.



Example: Model C211

The diagram shows how a dither matrix is used. In this machine, a 4 x 4 dither matrix is used,repeated many times so that it becomes the same size as the data for the scanned original.

The dither matrix contains threshold levels. Each pixel of the scanned image is compared with thethreshold level at the same location in the dither matrix. Then, each pixel changes to either black orwhite depending on whether the image data is greater or less than the threshold level. Thisprocedure is repeated for the whole of the original. In the example, the original is a single tone ofgrey, and the repeated pattern output from the dither matrix appears grey to the human eye.

5

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Main Scan

Image Data Dither Matrix Result

4-bit dataAll pixels at 5

SubScan

dith1.wmf



The thresholds in the dither matrix are designed so that half-tones can be reproduced on prints usingonly black and white pixels, by changing the ratio of black pixels to white pixels.

The matrixes can be adjusted in many machines to increase or decrease the detail on the copy.Also, the greater the number of lines in the matrix, the better the image quality in photo mode.

Example: Coarse and FineScreen Mode in Model C223

In this model a 12 x 12 dithermatrix is used to convert 8-bitimage data into single-bit data.The dither matrix for fine screenmode is different from the onefor coarse screen mode.

The diagram shows whathappens to an original with aconstant grey tone of grade 55(out of the possible 256).

Fine Screen Coarse Screen

1/400inch

dith2.wmf



Error Diffusion

The error diffusion process reduces the difference in contrast between light and dark areas of ahalftone image. Each pixel is corrected using the difference between it and the surrounding pixels.The corrected pixels are then compared with an error diffusion matrix.

Compared with dithering, error diffusion gives a better resolution, and is more suitable for“continuous toned” originals. On the other hand, dithering is more suitable for “screen printed”originals.

Error diffusion is often used in text/photo mode. Dithering reproduces text areas poorly, and with justa simple thresholding or grayscale process, photo areas do not come out well. Error diffusion is agood compromise because it reduces the contrast between light and dark areas of halftone images,while having no effect on letter areas.

Example: Model C226

Before a 6-bit image signal is converted into a single-bit signal based on the threshold level, there isa difference between the image signal value and the complete black value (63 for a 6-bit signal) orwhite value (0). With the Error Diffusion process, the difference is distributed among the surroundingpixels. (The MTF process simply erases these differences.)

When considering Error Diffusion in one dimension only (across the page), the 6-bit data shown inthe example below produces white and black data output as shown below. In practice, this one-dimensional Error Diffusion is done in all directions on each pixel (across the page, down the page,etc.).



In each dimension, the differencebetween the pixel value and the nearestextreme (0 or 63) is transferred to thenext pixel. The 1st pixel in the rowbecomes either black or white,whichever is closest. Then, for the1st pixel above, the differencebetween 7 and 0 is added to the 2ndpixel. The value of the 2nd pixel,which is now 18, is then added to the3rd pixel. The 4th pixel becomes 52,which is closer to 63 than 0. In suchcases, the difference is subtracted(not added) to get the next pixelvalue. In this example, the differenceis 63-52=11, and the next pixel value(30-11) becomes 19.

These values will then be treated byan error diffusion matrix.

c222d590.wmf

na2erdif.wmf



In Text/Photo Mode, the error diffusion matrix that is used may depend on the image area type (textor photo). Therefore, before error diffusion, a simple text/photo separation process is performed. Thiswas described in Text/Image Separation - Method 2: Comparison of adjacent pixels.

If error diffusion is used with binary picture processing, the output image signal level has just 2 levels(white and black).

If it is used with grayscale processing, the output image signal level has a number of levels (fromwhite to black). For example, in a machine with 256 grayscale output, the output from error diffusionmay use a small selection of these values, which are selected to give a good print quality.

Example: Model A229 (256 grey scales)

Photo mode – 17 levels per pixel

Text areas in text/photo mode – 9 levels per pixel

Photo areas in text /photo mode – 17 levels per pixel



Merging

Digital processing allows the user to combine other forms of data with the original before printing.

Common examples include printing the date and time, printing a message (such as 'Confidential'), orprinting a background pattern.

Make-up Mode

In make-up mode, the user scans command sheets before the original. Each command sheetspecifies an area of the original. Before making the copy, the user then specifies which effects to usefor the designated areas of the original. Typical effects include original type (text, photo, etc), use ofvarious colored inks, reversed image, and background patterns.

This is a common feature in Priport machines. Color copiers achieve something similar using aneditor touch screen on the operation panel.

Image Rotation

If the machine has paper of the same size as the original but different orientation, the image will berotated by 90 degrees in memory before printing. The machine must have enough working memoryto do this. The amount of memory required for a certain paper size depends on the image resolutionand the number of bits per pixel.

In the A229, 12 MB of DRAM is enough to hold two A4 images. This allows users to scan oneoriginal into the RAM while still copying from another. This only works for originals up to A4.



Combining Images

Using the memory, digital machines can print reduced images up to eight pages on one sheet ofcopy paper, or 16 pages using duplex mode.

If the locations of the printed images are arranged suitably, the user can make a small booklet out ofup to 16 originals, using duplex mode, then folding and cutting the copy.

Example: Model A133

comb1 wmfcomb2.wmf



Erasure of Irregular Dots

After the binary picture processing stage,some fax machines use patternrecognition to remove irregular dots.

Example: Model H515

If an element after being converted towhite or black by binary pictureprocessing is irregular against thesurrounding pixels, it is output in theopposite color. The central pixel iscompared with the surrounding eightpixels to determine whether this processis necessary. There are ten cases, asshown above, in which conversion isdone. This results in a cleaner image.

H515D647.wmf



Line Width Correction

This is normally only used when the user selectsCopied Original mode (making a copy of aphotocopy). This mode is known as ‘GenerationCopy’ mode in some machines.

Some copiers cause lines to bulge in the main scandirection as a result of the development system. So,pixels on edges between black and white areas arecompared with adjacent pixels, and if the pixel is ona line, the line thickness will be reduced.

For example, if the line on the original is one pixel inwidth, the pixel on the copy may be slightly largerthan one pixel width (as shown in the bottomdiagram) due to the shape of the dot made by thelaser beam and the amount of toner attracted to thepixel. If this copy is used as an original, imageprocessing may then generate additional blackpixels at the edges of the line, so the resultingprintout will have slightly thicker vertical lines inplaces. Line width correction attempts to correct forthis effect.

Original

Copy

Original Copy

Lwc.wmf



Edge Detection

In some fax machines, this process preserves the sharpness of image outlines. Each element istested to determine whether it is on a boundary of two areas of sharp contrast (such as the edge of acharacter on a white background). If the element is on a boundary, it goes straight to the cpu as ablack (1) element. (Halftone processing on this element could lead to a fuzzy outline.)

Edge detection uses a threshold, which can be adjusted by RAM address in some models if edges ofcharacters appear fuzzy.

Sub-scan Resolution Conversion

Fax machines have to consider the resolution of the printer at the other end of the telephone line.The sending terminal learns the capabilities of the printer at the other end through exchanges ofprotocol signals.

If the printer cannot print at the same resolution as the scanned data, the sending terminal mustmodify the data. Two methods can be used: Line Skipping, and Or Processing.

Line Skipping

Example: Model H516

If the user selects Fine resolution, the machine scans the document at a resolution of 15.4 lines/mmdown the page. However, if the other terminal can only receive at Detail resolution (7.7 lines/mm; halfthe resolution in Fine mode), alternate lines are deleted before transmission.



Or Processing

Or Processing combines two consecutive scanlines using a logical OR operation. An exampleis shown on the right.

In this way, only one line is sent in place of thetwo lines of scanned data. OR processingensures that the resulting single line accuratelyreflects the two consecutive lines that it isreplacing, in that no black pixels are deleted.

Example: Model H521

The scanner always scans at 15.4 lines/mm, sothe sub scan resolution has to be convertedwhen transmitting to a terminal which is notcapable of higher resolutions.

Standard (3.85 lines/mm): The first and thirdlines in each four-line group are OR processedfor transmission. Other lines are deleted.

Orpro1.wmf

Cut

Cut

ORProcessing 3.85 l/mm

Transmit

Feed1st Line

2nd Line

3rd Line

4th Line

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

H521D513.wmf



Detail (7.7 lines/mm): Pairs of lines are ORprocessed for transmission.

Fine: All the scanned lines are transmitted.

Transmit

ORProcessing

Feed

ORProcessing

7.7 l/mm

7.7 l/mm

1st Line

2nd Line

3rd Line

4th Line

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

H521D514.wmf

Transmit

Feed

1st Line

2nd Line

3rd Line

4th Line

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

15.4 l/mm

H521D515.wmf



Inch-mm Conversion

Multifunctional digital machines are usually designed to print in dot-per-inch format, to conform tointernational standards for office computer equipment.

However, in Group 3 fax standards, the data is transmitted in dot per mm format. If the scannerscans in dots per inch, the data must be converted to dot per mm format before transmission. Thescanner hardware and image processing circuits can work together to get the right format.


Main Scan Direction

The base copier's scanner always scans at 400 dpi in the main scan direction.

Then, the image processor processes the scanned data to get the required resolution and datawidth. This is the same process as Reduction in copy mode.

dpi: dots per inch, dpm: dots per mmReduction 400 dpi 200 dpi 16 dpm 8 dpmNo reduction 100.0% 50.0% 101.5% 51.0%A3 to B4 86.5% 43.0% 88.0% 44.0%A3 to A4 70.5% 35.0% 71.5% 36.0%B4 to A4 81.5% 41.0% 83.0% 41.5%



Sub Scan Direction

The base machine's scanner changes the motor speed to get the required resolution. However, if thereduction rate requires a faster speed than the scanner motor's maximum (37% reduction rate whenusing the ADF), the scanner and the image processor work together to get the required resolution asshown in the second table below.

lpi: lines per inch, lpm: lines per mm

Reduction 400 lpi 200 lpi 100 lpm 15.4 lpm 7.7 lpm 3.85 lpmNo reduction 100.0% 50.0% 25.0%2 97.8% 48.9% 24.5%7

A3 to B4 86.5% 43.2% 21.6%3 84.6% 42.3% 21.2%8

A3 to A4 70.5% 35.2%1 17.6%4 69.0% 34.5%6 17.3%9

B4 to A4 81.5% 40.8% 20.4%5 79.7% 39.8% 19.9%10

Numbers in superscript – Scanner and image processor both work together; refer to thefollowing table



Case Mode Reduction by Scanner Reduction by BiCUCase 1 (35.2%) 52.8% 66.7%

ADF 50.0% 50.0%Case 2 (25.0%)Book 25.0%

Case 3 (21.6%) 43.2% 50.0%Case 4 (17.6%) 52.8% 33.3%Case 5 (20.4%) 40.8% 50.0%Case 6 (34.5%) 51.9% 66.7%

ADF 48.9% 50.0%Case 7 (24.5%)Book 36.8% 66.7%

Case 8 (21.2%) 42.4% 50.0%Case 9 (17.3%) 51.9% 33.3%Case 10 (19.9%) 39.8% 50.0%

Inch - mm conversion causes a slight enlargement in the main scan direction and a slight reductionin the sub scan direction. This can be seen from the above tables. For example, changing 400 x 400dpi to 16 x 15.4 l/mm requires enlargement of 101.5% in the main scan direction and a reduction of97.8 in the sub scan direction.



Similarly, if a dot-per-inch based machine receives Group 3 fax data, it has to convert it to dot-per-mm format. It can also change the polygon mirror speed.

Example: Model A120

13132.44 rpm (dot-per-mm mode), 13385.83 rpm (dpi mode)

We will mention this again in the Laser Exposure section.



Image Rotation Before Transmission

In copiers with fax boards, it ispossible to place an A4 or Lettersize original sideways on theexposure glass. In this case, theoriginal will be treated as an A3(DLT) width original, and reduced toA4 before transmission.

Also, if an A5 (half-letter) original isplaced lengthwise on the exposureglass, the image will be sent as A4(LT) with a lot of blank space at oneedge.

However, the Image Rotation Before Transmission feature prevents these things from happening, byrotating the image before sending it out.

Sub Scan(< 210mm/8.5")

Main

Sca

n(2

97

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/11

")

1st Pixel

1st

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Scanned ImageOriginal Transmitted Image

a693d503.wmf



Black and White CIS Systems

Contact Image SensorsSome low-price compact fax machines and Priports use a contact image sensor (CIS) instead of aCCD. A CIS consists of a strip of photodiodes to illuminate the document, and a strip ofphototransistors covered by a row of self-focusing lenses. If a CIS is used, a long light path is notneeded, because the CIS contacts the document directly, so the size of the scanner can be greatlyreduced (no mirrors, lenses, or shading plates are needed). When using a fluorescentlamp/lens/CCD arrangement, the light path is about 300 to 500 mm. However, a CIS is positionedless than 0.1 mm above the surface of the paper.

However, the built-in analog processing circuits in CIS assemblies are inferior to the videoprocessors of CCD models.

Originally, using a contact image sensor instead of a CCD removed the necessity of the complicatedadjustments needed for a CCD scanner. However, CCD assemblies need no adjustments in the fieldnowadays, so they are used now only for cost and space reduction.



The diagram shows a typical CIS scanner.

The scanner consists of a shading plate [A]and a contact image sensor (CIS) assembly[B]. Inside the CIS are an exposure glass[C], a self-focusing lens array [D], an imagesensor [E], and an LED array [F].

The image sensor is a row of 1728photosensitive elements (A4 width, 8dots/mm). The LED array illuminates theoriginal. The self-focusing lens arrayfocuses light reflected from the original ontothe image sensor.

Because of the short optical path inside the CIS, the focal depth is much shorter than for a CCD typescanner. Because of this, a spring pushes the shading plate against the document so that thedocument surface always touches the exposure glass at the scan line, and the distance between theCIS and the original is constant.

However in book scanning mode, if the original is out of the CIS focal range, the scanned image mayget darker.

H505D522.wmf

[A]

[B]

[C]

[D]

[E]

[F]



Analog Signal ProcessingAuto shading and other processes already described for the CCD are also used in CIS scanners.The only new ones are as follows.

Zeroing the Signal and Correcting the Amplification Ratio

Example: Model H516

The image sensor generates acertain voltage even if thescanner lamp is not turned on.To correct for this, the machineautomatically adjusts the groundlevel of the sensor output, if thepeak voltage of the analog videosignal exceeds 234 mV when thelamp is off.

Then, the machine adjusts the signal's amplification ratio if the peak output level of the analog videosignal while the scanner lamp is on is lower than 1.72V.

The machine will execute the above adjustments automatically, just before scanning the first page.Refer to the waveforms in the diagram to see how these adjustments work.

LED OFF

GND

VOFFCNT = Low Peak Level

GND

VGCOM = Low

LED ON

Peak Level

H516D565.wmf



Sampling Clock Selection

The image sensor output is a sawtooth waveform. So the sensor output level depends on thesampling clock selected as shown in the above diagram.

The clock is adjusted at the factory. But for some models, the clock should be reset using a servicefunction whenever the image sensor is replaced.

Example: Model H521

Scanner Lamp ON

Scanner Lamp OFF

Clock 0

Clock 6

Clock 7

Clock 5

Clock 4

Clock 3

Clock 2

Clock 1



Digital Signal ProcessingAll the features discussed for the CCD apply here also. There is another one that appears in Priportsthat use a CIS.

Paste Shadow Erase Mode

Due to the characteristics of the contact image sensor, shadows tend to appear on copies of paste-up originals. To counter this, pressing a key on the operation panel allows use of paste shadowerase mode.

When this mode is selected, the black or white threshold level (used in binary picture processing) isslightly lowered. At the same time, the strength of the MTF process in the sub-scan direction isweakened to make the shadows inconspicuous.



Color Systems

OverviewThis section will explain image processing incolor copiers.

Color CCD

The color CCD converts light reflected from theoriginal into three analog signals, one for eachof the three basic colors Red, Green, and Blue.The signals are called the R, G, and B signals.Each of the four scans (for toner colors YMCK)uses all three signals (RGB).

The CCD consists of three lines of 5000elements at a resolution of 400 dpi (15.7 dots/mm). Tomake the R, G, and B signals, each line has a colorseparation filter (R, G, or B).

The lines are spaced 8 pixels apart for full sizemagnification. To correct for these spacings, the R, G,and B signals must be synchronized. This is done usinga memory work area in the image processing circuits.

Col-ccd1.wmf

A166D540.wmf



A filter removes infra-red; this is particularly important for glossy photos containing black areas,which can appear reddish in copies.

Most color copiers do not have enough memory for the scanned RGB data to be processed andconverted to KCMY data all at once. Therefore, one scan is needed for each toner color that will beused in the copy. For example, for a full color copy, the original is scanned four times, as follows:

• First scan: The video processing circuits make K data from the scanned RGB data.

• Second scan: The circuits make C data from the RGB data.

• Third scan: The circuits make M data from the RGB data.

• Fourth scan: The circuits make Y data from the RGB data.

Analog Signal ProcessingThese are similar to the processes for black-and-white copiers, except for the following.

Auto Shading

This is done before the black scan.



Digital Signal Processing

Scan Line Correction

The three CCD lines providing the RGB signals are several scan lines apart (typically 8 scan linesapart) when full size magnification is used. To compensate for this discrepancy, the line correctioncircuits synchronise the output timing of the RGB signals to the digital processing circuits by storingthe data for each line in memory.

The discrepancy between RGB video signals depends on the reproduction ratio, and this is takeninto account in the correction.

Example: Model A166

• B: Standard (No correction)

• G: (8 lines) x (Reproduction ratio)

• R: (16 lines) x (Reproduction ratio)

If this calculation does not result in aninteger (for example if the reproductionratio is 90%), the correction factor is set tothe closest integer, but further correction isneeded (refer to Picture ElementCorrection). A166D505.wmf



Picture Element Correction

The target areas for this correction are shown in the diagram. The Picture Element Correction circuitdoes two things.

1. Completion of the Scan Line Correctionprocess

This is done if the scan line correctionprocess did not result in an integer.

2. Correction if the CCD is not perpendicularto the light

If the CCD board is not perpendicular to thelight axis, the position of each pixel isdifferent from the original image position.This difference becomes larger towards theends. Under this condition, vertical black lines(in the sub-scan direction) at the left and rightedges of the original are colored because theY, M, and C toner dots are not properlypositioned. (An example of this is the verticallines at the right and left edges of the C4color chart.)

For this second stage, the green CCD line is taken as a standard, and the ends of the red and bluelines are corrected.

A166D509.wmf



Scanner Gamma Correction

The RGB video signals detected by the CCDare converted to 8-bit digital signals. Thesesignals are proportional to the light intensityreflected from the original image (see the firstdiagram).

However, the image processor converts thesignal levels as shown in the second diagramby using a gamma correction table. This tablereverses the output of the video signal for eachcolor, and this improves the accuracy of RGBto CMY color conversion, which is done laterin the image process. The same table is usedfor R, G, and B signals.

A166D507.wmf

A166D508.wmf



The scanner γ correction converts the video signal levels as follows:

Dark (Black) Light (White)Scanner Input (RGB) 0 255After γ Correction (RGB) 255 0

↓ Color ConversionPrinter Output (CMYK) 255 0

The reversal is not linear. Dark areas need finer gradations for better copy quality.



ACS (Auto Color Selection)

Auto color selection mode determines if an originalis black/white or color. Then black copy mode or fullcolor mode is automatically selected to match theoriginal.

To recognize if the original has a colored area ornot, the RGB video signals are compared. If themaximum difference among RGB signal levels(MAX-MIN in the above diagram) is within a certainrange, the original is considered black and white.

Increasing the value of MAX-MIN makes it morelikely that an original will be treated as a black-and-white original.

During the 1st scanning cycle, the latent image is developed with the amount of black toner asspecified by the gamma-corrected RGB video signals. If the original does not have any color areas,the 2nd scanning is aborted and the developed image is transferred from the transfer belt to the copypaper. Then the black and white copy comes out. If the original has a colored area, copying resumesin the full color copy mode (4 scans).

Users can maximize the quality of their output by selecting priority for Black or Full color originalwhen using ACS mode. This will be discussed in more detail later in the section on Under ColorRemoval (UCR)

A166D510.wmf



Auto Text/Image Separation

This is similar to the method alreadydescribed for black-and-white systems.However, there is an extra step fordetermining which parts of text areas areblack and which are colored.

Black pixels and color pixels in text areas areidentified by determining the differencesbetween the maximums of the RGB signalsand by evaluating the output levels of theRGB video signals.

The edge separation and dot screen detection steps are similar to those described for black-and-white systems, but they are done using the green data signal only.

Auto letter/photo separation is mostly effective only for small letters or thin line diagram elements. Ifthere are big letters or solid line drawing elements in the original, only the edges of these areprocessed using text mode; the inner regions are processed using photo mode.

RGB Filtering

The appropriate filters are applied to the R/B/G video signals, depending on the selected imagemodes (text/image) or the result of Auto Text/Image separation.

A166d513.wmf



Smoothing Filter

The smoothing filter improves the image by smoothing the gradient between pixels in half-toneareas.

A166D514.wmf A166D515.wmf

Before

After



Edge Emphasis Filter (High Contrast Filter)

The high contrast filter improves letters by making the edges of text and line art elements stand outmore clearly.

These two types of filter are applied again in some models after conversion from RGB to CMYK. (Inthe drawing, it is shown being used on CMYK data after color conversion.)

The user can adjust the strengths of these filters to make the image sharper or softer.

A166D520.wmfA166D521.wmf

Before

After



Auto Image Density Control

This prevents the background of an original from appearing on copies.

Example: Model A166

If the user does not select ADS mode, the machine removes low ID image signals (background) thatare less than a certain threshold. The threshold that is applied depends on the color mode (singlecolor or full color). If the threshold is too high, colored backgrounds could be erased.

Image Density

Threshold

0

Main Scan LineA166D522.wmf

Image Density

0

Main Scan LineA166D524.wmf



If the user selects ADS mode, the machinecalculates the threshold, guided by input from theuser (there are 4 settings for black-and-white, and4 for full color).

In full color mode, after the first scanning (Bk) themachine calculates the threshold for removingbackground by referring to the RGB data takenfrom the whole of the original.

In black and white mode, the machine calculatesthe threshold for each pixel by referring toneighboring pixels.

A166D523.wmf



Color Conversion

The transparency of each color toner is notideal, as shown in the diagram.

Color conversion compensates for thedifference between ideal and actualcharacteristics.

RGB video signals from each scanning cycleare converted to YMCK video signals using amatrix.

Example: Model A166

Original ColorToner Bk R Y G C B M WY 1 1 1 1 0 0 0 0M 1 1 0 0 0 1 1 0C 1 0 0 1 1 1 0 0Bk 1 0 0 0 0 0 0 0

Some user and SP modes can change the contents of the matrix.

Examples: To change the color balance of the output, to allow three types of photo mode (PrintedPhoto, Glossy Photo, and Copied Photo).

A166D516.wmf



Positive/Negative Reverse

In the positive/negative image mode, colors are changed to their complements, as shown below:

Red – CyanGreen – MagentaBlue – YellowYellow – BlueMagenta – GreenCyan – RedBlack – WhiteWhite – Black

Posneg1.wmfPosneg2.wmf



UCR (Under Color Removal)Principle

Getting the right colors using YMC toner addition does not always work perfectly. For example, equalamounts of Y, M, and C toner should give Black. However, the result is a dark blue.

UCR compensates for this by removing equal amounts of each color toner and replacing them withblack toner.

The UCR ratio is the percentage of the common ID value for YMC that is subtracted and convertedto Black. In the above example, where the UCR ratio is 100%; the entire common ID value issubtracted from Y, M, and C, and converted to Bk.

In actual use, the UCR ratio depends on the color mode and the image density. For example, whenthe UCR ratio is 95%, 95% of the entire common ID value is subtracted from Y, M, and C, andconverted to Bk.

A166D525.wmf



In the following examples, the UCR ratio is 70%.

For a Black Image

When a black image is copied, the ID valuesfor all colors are equal (diagram on the left).

For each color, the ID value is reduced by theUCR ratio (70% in this example).

A black ID value equal to the 70% reductionis added to compensate for the color IDreduction (diagram on the right).

For a Color Image

When a color image is copied, the color ID values are different from oneanother. It is treated in three steps.

IDValue

Y

Y

M

M K

C

C

30%

70%

Ucr1.wmf

IDValue

Y M C

Ucr2.wmf

Result after70% UCR



1. The ID value for this image is broken downinto two parts: a set of values equal to thelowest color ID value, and the remainders ofthe two higher values.

2. The part with the equal values is treated as ablack image (see “For a Black Image” on theprevious page), using the 70% UCR ratio.

3. The resulting amounts are then added tothe remainders from step 1. The finalresult gives us the ID value for each colorand for black.

IDValue

Y M C Y M C CY

Ucr3.wmf

IDValue

Y

Y

M

M K

C

C

30%

70%

Ucr1.wmf

IDValue

Y YM MC CK KY CUcr4.wmf

Blackcomponent

Colorcomponent

Black componentafter 70% UCR

Color componentunchanged

RESULT



Changes in UCR Ratio with Image Density and Copy Mode

Example: Model A166

Also, the user can select either B/W Priority or Color Priority, to reproduce the B/W areas or Colorareas well, when the ACS mode is selected.

- Letter Areas -

The UCR ratio in letter areas is always 100%. The UCR ratio is set to 100% to reproduce the letterareas well. Black toner is always used if MIN (RGB Common Data) is greater than zero, and thevalue of MIN determines how much black toner is used.

A166D510.wmfA166D511.wmf



- Photo Areas, with ACS Priority set to Bk -

In photo areas, Bk toner is not used until MIN reaches a certain value.

When the user sets the ACS priority to Bk, UCR begins to replace color toner with Bk toner at lowimage densities (when MIN is about 13 – see the diagram on the previous page). This is to preventthe UCR process from reducing the image density too much in low image density areas.

At this point, the UCR ratio is zero. As shown in the graph above right (on the previous page), itgradually rises with image density, and the UCR ratio is about 100% when MIN is 255.

The UCR ratio changes with image density. The steeper the gradient in the above graph, the fasterthe UCR ratio increases with image density (as MIN increases).

- Photo Areas, with ACS Priority set to Full Color -

When the user sets the ACS priority to Full Color, the UCR process does not begin to replace colortoner with Bk toner until a low-medium image density (when MIN is about 102 – see the diagram).

At this point, the UCR ratio is zero. It gradually rises with image density, and the UCR ratio is about95% when MIN is 255.



Determining the UCR Ratio

To get the UCR ratio for any MINvalue, draw a line up from the MINvalue on the x axis until it reachesthe line corresponding to Lettermode. Measure this length (LT), andmeasure the length (MODE) up towhere this vertical line crosses theline for the copy mode being used.Because the UCR ratio for lettermode is always 100%, the UCR ratiofor this MIN value with this copymode is (MODE/LT) x 100%.

UCR = 100%

MODE

LT

A 255

UCR Ratio at A = X 100%Mode

LT Ucrcalc.wmf



When the user uses the UCR AdjustmentUser Tool, the UCR ratio for each imagedensity will change, so the gradient andintercept of the line for color mode willchange.

Example: Model A172

The diagram shows an example.

UCR ratio: 100%

UCRsetting 1

23

4

56

78

0 255

255 : Letter areas

: Photo areas

RGB Common Data

Bk Conversion Data

9

a172d527.wmf



UCA (Under Color Addition)

Using only UCR processing, the copy lacksdepth. So, a specified ratio of toner is added foreach color (YMC only). The amount of additionaltoner is proportional to the density of that color onthe copy.

UCA is only done in text and line-art areas. Inthese areas, UCR is 100%, so some color mayneed to be added back. In photo areas, the UCRratio changes with image density, so UCA is notneeded.

Increase the UCA level if dark colors areappearing black on the copy. Decrease the valueif pure black on the original is not pure black onthe copy.

Y YM MC

UCA

CK KUca.wmf



Printer Gamma Correction and Auto Color Calibration

KCMY Gamma

A gamma curve describes the relation between the image density of the original and that of the copy.The relationship is not linear: doubling the ID of an original does not double the ID of the copy.

The printer characteristics are much more variable than the scanner. Therefore, the printer gammaneeds recalibration and adjustment from time to time.

Ideally, the gamma curves for Yellow, Magenta, Cyan, and Black should be identical, as shown in inthe diagram above left. However, they are not, because electrical components always vary slightly,resulting in varying gamma curves, as shown in the diagram above right.

A166D528.wmf A166D529.wmf



To compensate for this discrepancy, the Auto Color Calibration (ACC) procedure can be done if colorreproduction is becoming unsatisfactory. ACC makes new gamma curves for each color in eachmode (letter, photo, black letter, glossy photo). After ACC, the gamma curve for each color can beadjusted with service programs.

Using these programs, each gamma curve can be adjusted using 4 different modes: ID max., HighID, Middle ID, and Low ID, as shown on the following page. (ID = Image Density)

Example: Model A109

- ID max. -

This mode is used to adjust the total imagedensity level.

HLL

H

IDMAX

Darker

Copy ID

Original ID

Lighter

If thevalue is incrementedby 1,the IDis increasedby 5%

10

0

10

0

Prtgam2.wmf



– High ID –

The High ID mode should be used to adjust theimage density between Level 6 and Level 9 of thecolor gradation scale on the C-4 test chart.

– Middle ID –

The Middle ID mode should be used to adjust theimage density between Level 3 and Level 7 of thecolor gradation scale on the C-4 test chart.

Darker

High ID

Copy ID

Original ID

Lighter

HLL

H20

0

20

0

Prtgam3.wmf

Darker

Middle IDCopy ID

Original ID

Lighter

HLL

H

30

0

0

30

Prtgam5.wmf



– Low ID –

The Low ID mode should be used to adjust theimage density between Level 2 and Level 5 ofthe color gradation scale on the C-4 test chart.

Darker

LowID

Copy ID

Original ID

Lighter

HLL

H

20

0

20

0

Prtgam4.wmf



Image Density

This shows how the gamma curve can be adjustedto change the image density.

Contrast

This shows how the gamma curve can be adjustedto change the contrast between light parts and darkparts of the image. The slope of the line in thegraph changes, but stays centered around point"A".

Copy ID

Original IDHL

L

H 1

5

9

Prtgam6.wmf

Copy ID

Strong

Strong

Weak

Weak

Original ID

A

HLL

H

Prtgam7.wmf



Pastel Mode

This shows how the gamma curves can be adjustedto produce pastel mode images. Another way to dothis is by changing the parameters of the colorconversion matrix.

Color Balance

The balance between the four colors CMYK can be changed by altering the gamma curves. Anotherway to do this is by changing the parameters of the color conversion matrix.

Copy ID

Original ID HLL

H

9steps

Prtgam8.wmf



Auto Color Calibration (ACC)

Example: Model A172

This machine automatically calibrates the printergamma curve when the user selects ACC.

A test pattern, including the patterns for Lettermode and Photo mode, will be printed first. Theuser then scans the test pattern. and themachine corrects the printer gamma bycomparing the ideal settings with the currentimage density.

The test pattern consists of eight lines, one foreach color (KCMY) in letter mode, and one foreach color in photo mode.

There are adjustment tables for L, M, H, and IDMAX values stored in the machine. The machineapplies these to approximate the actual curve tothe target curve as closely as possible. If needed,the printer gamma curve can be adjusted furthermanually using a procedure called Color BalanceAdjustment.

A172D534.wmf

L M H

Target γ

Actual γ

Image Density

A172D540.wmf9 August 2003 Page 304

Digital Processes Printer Engines

Printer Engines Laser Printing

Outline This section of the manual explains the optical and video data processing components of the laser printing system. It also explains how the printout data signal is generated from the received image data. The machine uses a laser diode to produce electrostatic latent images on the photoconductor. This gives high print quality and enables high-speed writing. The laser diode unit converts received image data into laser pulses, and the optical components direct these pulses to the photoconductor, where the laser beam forms a latent image. Notes 1. Every model has safety features to stop the laser if the photoconductor is not present or if certain

covers are open. Interlock switches are normally used to ensure these safety conditions. 2. Always observe the following cautions when servicing a laser printer:

• Never remove the laser unit cover while the main switch is on.

• Never remove any components of the laser circuit when the main switch is on.

• Never touch the surface of the optical components.



The Latent Image Exposure of the photoconductor to the laser beam creates the latent image. A rotating mirror moves the laser beam across the photoconductor to make the main scan while photoconductor rotation controls the sub-scan. In this example, the photoconductor is charged to about -780 V. The charge on irradiated areas drops significantly, typically to between 0 and -100 V. (Voltage values differ from model to model.) The area that is irradiated depends on whether the 'write to white 'or 'write to black' method is being used. Most machines use the 'write to black' method. (See Digital Processes Digital Images Printer Output.)

Main Scan(Laser Beam Movement)

Sub-scan(Photoconductor Rotation)

Laseropt.wmf



Optical Path The diagram shows the typical optical components of a laser printer.

Example: Model A133 The laser diode emits a thin pencil-like laser beam. This beam is reflected by a rapidly spinning polygonal mirror (a 5, 6, or 8-sided mirror is normally used). Each face of the mirror scans the laser beam across one main scan line on the photoconductor. The photoconductor then moves down one line, and the beam from the next face of the mirror writes the next main scan line. The beam then passes to the photoconductor through the various optical components. At the start of each main scan, the laser hits the laser synchronization detector. This detector then synchronizes the electronics for the start of a new scan line. This machine has two detectors; the reason for that will be explained later in this section.

[G][H]

[A]

[B] [C]

[D] [E]

[J][F]

[ I ]

A133d613.wmfA: Laser Diode Unit E: Laser Synchronization Detector Board-2 B: Fθ Lenses F: Laser Synchronization Detector Board-1 C: BTL (Barrel Toroidal Lens) G: Polygon Mirror Motor D: Drum Mirror H: Cylindrical Lens I: OPC Drum J: Toner Shield Glass



Optical Components The components of the optical path are described in the following pages. The actual components used and their names may differ from model to model.

Laser Diode Unit This consists of the laser diode, collimating lens, aperture, and laser diode drive board. The laser diode (sometimes called LD for short) radiates laser beams of a wavelength of 780 nm, which is in the far red to near infra-red range of the spectrum. The power of the laser beam depends on the type of photoconductor used, and on the paper feed speed (a faster engine needs a stronger laser, if the photoconductor type is the same). A typical example is 0.6 mW for the A193. The collimating lens forms the radiating beams into a parallel flux, which passes to the cylindrical lens. The cross section of the beam at the aperture is an ellipse about 2.6 mm long by 0.5 mm wide. Some models have two laser diodes. This is explained in Dual Laser Beam Printing.

Laser Beam

Laser Diode

Laser DiodeDrive Board Collimating Lens

Aperture

Lsrcmp1.wmf



Cylindrical Lens The cylindrical lens focuses the beam and sends it to the rotating polygonal mirror.

Polygonal Mirror The faces of the mirror are precision-ground for high reflectivity, and to prevent pixel misalignments in the main and sub-scan directions. The mirror rotates at a constant speed, which varies from model to model. As the mirror reflects the laser beam, its rotation scans the beam across the photoconductor, via lenses and mirrors. The beam reflected from one face of the polygonal mirror makes one main scan across the photoconductor. This is illustrated below.

LaserDiodeUnit

CylindricalLens

Beam Cross-sectionLsrcmp2.wmf

Lsrcmp3.pcx

Mirror

Motor

Drive Board



The relation between mirror face orientation and scanning is as follows. 1. Laser synchronization (main scan start) detector position 2. Main scan start position 3. Main scan intermediate position 4. Main scan end position (1) to (4) are repeated for each line. One scan line on the photoconductor is scanned by one face of the mirror. The above set of diagrams illustrates the main scan. When the beam hits the main scan start detector mirror (1), the CPU recognizes that a new line is about to be scanned. As the mirror rotates, the beam scans across the photoconductor [(2) - (3) - (4)]. Normally, there is no main scan end sensor at (4) because, as the mirror rotates and the beam hits the next face, the beam is instantly deflected to the vicinity of (1) and a new main scan begins. However, some machines have a sensor at the end of the main scan, and this will be explained later.

(3)

(4)

(2) (1)

Laser Beam

Lsrcmp4.wmf



Fθθθθ Lenses The angles between picture element beams are equal. However, the diameters of each element beam projected onto the photoconductor are different, being thicker at both ends of the main scan than in the center, as shown in the upper diagram. The Fθ (F-theta) lenses correct for this.

The Fθ lenses correct the laser beam so that it passes over the photoconductor at a constant speed. The lenses deflect the beam slightly inward to ensure that the diameters of all picture elements are equal.

Thick

Thin

Polygonal Mirror

Lsrcmp5.wmf

Lsrcmp6.wmf



Second Mirror The second mirror reflects the corrected laser beam to the focusing lens. There may be more than one mirror in this position, if the optical path is not straight.

Focusing Lens This lens corrects the beam for face irregularities on the polygonal mirror and second mirror, and focuses the beam onto the photoconductor. In printers where the photoconductor is close to the lens, a cylindrical lens is often used in this position. However, if the photoconductor is not close to the lens, a cylindrical lens would leave the left and right edges of the image blurred. In these models, a focusing lens (sometimes called a barrel toroidal lens) is used; this lens operates similarly to an Fθ lens. The barrel toroidal lens is also used when plastic Fθ lenses are used to reduce costs. With plastic lenses, it is difficult to get the required beam deflection with Fθ lenses only.

PolygonalMirror

SecondMirror

FocusingLens

F Lensesθ

Photoconductor Lsrcmp7.wmf

PolygonalMirror

Beams reflectedinaccurately because ofmirror face irregularities

SecondMirror

FocusingLens

F Lensesθ

Photoconductor

Accuratelyreflected beam

Lsrcmp8.wmf



The cross section of the beam on the photoconductor (i.e., the size of each printed dot) varies from model to model; it is roughly circular, with a diameter in the region of 80 mm. This means that the printed dots overlap each other slightly, as seen below in a typical example.

Example: Model H006 80 mm is about 12 dots per mm, and 90 mm is about 11 dots per mm. However, the printer resolution is 16 x 15.4 dots per mm. The dots are larger than this resolution, so they overlap. This results in a better image than if there were no overlap.

Lsrcmp9.wmf



Laser Synchronization Detector

Single-detector System Mechanism

Example: Model H006 The laser synchronization detector (sometimes known as the main scan start detector) synchronizes the main scan start timing of the laser beam across the photoconductor. Each face of the polygonal mirror scans the laser beam across the photoconductor for one main scan. Just before the laser beam starts scanning across the photoconductor, it hits the laser synchronization detector. The signal from the detector informs the cpu that a new main scan is about to start. The cpu then synchronizes the electronics for the start of the new scan line. The laser synchronization detector is a phototransistor. In some models, it is connected with a fibre optic cable.

Lsrcmp10.wmf

Polygonal Mirror

Fθ Lenses Second Mirror

Fibre Optic Cable



Circuit

Example: Model H006 Just before the laser beam starts scanning across the photoconductor, it hits the main scan start detector. An optic fiber or a mirror routes the laser beam to the detector. The detector output passes to a comparator. The comparator output [A] goes high when activated by the laser beam. It remains high for a few microseconds. The signal passes to the Laser Interface (LIF). An oscillator sends a clock signal to the clock generator. The clock generator generates eight clock signals (CK0 to CK7) from this clock. Each of these has the same frequency as the original clock signal, but there is a fixed phase difference of 30 to 40 nanoseconds (depending on the model) between each of the eight output signals. (A thousand million nanoseconds make one second.) The LIF selects one of these eight signals to time data output for the main scan line that is about to start. The selection process is shown below.

Detector

+5V+5V

+

_

Comparator

+5VD

Oscillator

CK0-7

Clock Generator

Clock

[A]

Laser DiodeDriveBoard

LIF

Lsrcmp11.wmf



As shown in the timing chart, the eight clock signals CK0 to CK7 have the same frequency but are out of phase with each other. The signal chosen is the one that has the nearest rising edge immediately after the signal from the main scan start detector goes high. Here, CK2 is selected. The process is repeated at the start of each scan line. In some models, the signal with the nearest rising edge before the main scan start signal is chosen; CK1 would be selected in the above example.

CK0

CK1

CK2

CK3

CK4

CK5

CK6

CK7

SYNCLsrcmp12.wmf



Double-detector System Example: Model A133 Some of the optical components are made of plastic, and may expand and contract with changes of temperature. If this happens, the number of pulses in the laser main scan across the photoconductor will vary. To counteract the effects of this, the machine adjusts the frequency of the laser pulses to keep the number of laser pulses in each main scan constant. To do this, the machine has two laser synchronizing detector boards [A] and [B], one at each end of the main scan line. They measure the number of clock pulses between the start and end of each main scan. (These clock pulses are from the base clock, which is at a much higher frequency than the laser frequency.) If the number of pulses is not correct, the machine adjusts the frequency of the laser to keep the number of laser pulses in each main scan constant. The laser synchronizing detector board-1 [B] synchronizes the main scan start timing. At the other side, the laser synchronizing detector board-2 [A] counts the number of clock pulses since detector board-1 was activated.

[A]

[B]

A133-613.wmf



Dual Laser Beam Printing System

Overview Example: Model A230 This LD unit has two laser diodes, [A] and [B]. This means that each face of the six-sided polygon mirror writes two main scan lines, and twelve main scans are produced when the mirror rotates once. This mechanism:

• Reduces the mirror motor rotation speed • Reduces the noise generated by the

polygon mirror motor • Reduces the image data clock frequency, to

allow high speed printing without costlier high-speed components

Two laser beams go to the polygon mirror [C] through collimating lens [D] and prism [E]. They arrive on the drum surface about 2 mm away from each other in the main scan direction and about 0.06 mm (at 400 dpi) in the sub scan direction.

[A]

[B]

[C]

[D]

[E]

A230D203.WMF



The reason for the two-mm difference in the main scan direction is so that the machine can detect a laser synchronization signal for each beam.

Laser Beam Pitch Change Mechanism Example: Model A230 When this machine receives data from a printer, it must print at 600 dpi. The machine changes the resolution between 400 and 600 dpi by rotating the LD unit. When the LD positioning motor [A] turns, the metal block [B] (which contacts the LD unit housing [C]) moves up and down. This changes the position of the L2 laser beam (L1 does not move). Both LD unit positions are at fixed distances from the LD home position sensor [D] (measured by motor pulses). Usually, the LD unit moves directly to the proper position. However, when the number of times that the resolution has changed reaches a certain value, the LD unit moves to the home position (the home position sensor activates), then it moves to the proper position. This recalibrates the LD unit positioning mechanism.

A231D503.WMF

[A]

[B][C][D]

P1

2 mm

P2

P1: 400 dpi P2: 600 dpi



Laser Diode Power Control Even if a constant electric current is applied to the laser diode, the intensity of the output light changes with the temperature. The intensity of the output decreases as the temperature increases. In order to keep the output level constant, the output light intensity is monitored through a photodiode enclosed in the laser diode. The photodiode passes an electrical current that is proportional to the light intensity. The output is not affected by temperature, so it faithfully reflects the changes in the LD output, without adding anything itself.

Example: Model A133 Just after the main switch is turned on, and every pixel during printing, IC2 on the LD drive board excites the laser diode at full power and stores the output of the photodiode (PD) as a reference. IC2 monitors the current passing through the photodiode. Then it increases or decreases the current to the laser diode as necessary, comparing the output with the reference level. The laser power level is adjusted on the production line. Do not touch the variable resistors on the LD unit in the field.

IC2IC1LVL1

LD5 V

+5 V

VIDEO

LEVEL

LD OFF

LD Drive Board

LD

PD

A133d618.wmf



Laser Signal Profile The cpu does not send a continuous stream of video data to the laser diode. If it did that, the start of each line of data would not be properly synchronized. The transfer of data to the laser diode is made line by line, using the signal from the main scan start detector to synchronize the signal. The following timing chart shows how each main scan line of data is sent to the laser diode. One page of data will consist of many repetitions of this basic signal profile. When the CPU detects the main scan start synchronization signal, it turns off the laser beam. After a short while, it turns back on. The amount of white dummy bits marked "b" on the diagram depend on the paper width; the number of bits "a" are fixed. The main scan line data follows ("c" on the diagram), then more dummy bits (the amount of the dummy bits marked "d" depends on paper width; the bits marked "e", "f", and "g" on the diagram are fixed). During "c", the signal will switch between high and low in accordance with the data signal. It also switches on and off between pixels. At point 7 on the timing chart, the laser beam turns back on so that it can activate the main scan start detector.

On

Offa b c d e

f

g h

4799dotsSynchronizationSignal

DetectedSynchronization Signal

Detected

1 2 3 4 5 6 7

Lasersig.wmf(1) Main scan start synchronization signal detected (2) Dummy bits ("a" and "b" on the diagram) (3) One main scan line of data ("c" on the diagram) (4) Dummy bits ("d" and "e" on the diagram) (5) Dummy bits ("f" on the diagram) (6) Dummy bits ("g" on the diagram) (7) Laser on, ready to activate sensor ("h" on the diagram)



The signal profile on the previous page is for a "write to black" printing process. In a "write to white" process, the signal profile is similar, except that dummy bits "b" and "d" are high instead of low. Also, the polarity of the data signal during "c" is the reverse. The duration of one cycle depends on the rotation speed of the polygon mirror.

Example: Models A229 at 400 dpi Six-sided mirror, rotation speed: 25984 rpm Duration: 60/(25984 x 6) s = About 0.38 ms



Image Processing

Printer Gamma Correction Printer gamma correction corrects the data output from the image processing circuits to the laser diode to account for the characteristics of the printer (e.g., the characteristics of the drum, laser diode, and lenses). Printer gamma correction is done after image processing, before the data goes to the laser diode.

Prtgam1.wmf



Gradation Processing This section explains how a laser printer reproduces grayscales. To make the latent image, the laser beam illuminates the image area of the drum surface. The longer the laser is on and the brighter it is, the darker the developed pixel becomes.

Changing the duration (also called the width) of the pulse is known as Pulse Width Modulation (PWM). Models with this feature typically have 8 possible pulse width levels.

876543210

1 2 3 4 5 6 7 8

Pulse WidthModulation

8 Levels

PowerModulation

8 LevelsGreyscale

1Greyscale

4Greyscale

8Greyscale

12Greyscale

16Greyscale

34Greyscale

64

Lasgrad1.wmf



While the laser is on to make a dot, the laser can be made brighter or dimmer. This is known as power modulation (PM). The lasers intensity is controlled by the amount of current sent to the laser diode. Models with this feature typically have either 8 or 64 possible power levels. The PWM and PM levels are combined to reproduce the various grades in the grey scale. Examples A193: 8 PWM levels, 8 PM levels, giving 64 possible greyscale levels per pixel A229: 8 PWM levels, 64 PM levels, giving 256 possible greyscale levels per pixel G020: 8 PWM levels, 0 PM levels, giving 8 possible greyscale levels per pixel The power is modulated only on the final part of the laser pulse (example: see Greyscale 12 or 34 in the diagram). For example: Greyscale 34 is made from PWM level 4 and PM level 2



Some machines having a high number of possible grayscales per pixel do not use them all.

Example: Model A229 The 8-bit data from the image processing circuits (enough for 256 grayscales per pixel) are converted to 4-bit data for the laser diode drive board (only enough for 16 grayscales per pixel). However, the machine emulates 256 grayscales by dealing with the output in blocks of 16 pixels (4 x 4), using the 16 grades per pixel in each of the 16 pixels in the block to produce 256 grayscales for blocks of 4 x 4 pixels. The drawing shows an example of the principle. This data is not taken from any machine; it is just a fictitious example. This technique is important for machines like the G020, which has only 8 grayscales per pixel. This machine emulates 256 grayscales in a similar manner.

1 1 1 1

1 1 1 1

1 1 1 1

1 1 1 1

4 3 5 3

3 5 4 4

5 4 5 3

3 5 3 5

6 8 6 8

8 7 8 6

6 8 7 7

7 6 8 7

16 16 16 16

16 16 16 16

16 16 16 16

16 16 16 16

11 10 14 12

10 14 12 11

14 13 12 11

10 12 14 13

Greyscale 1 Greyscale 50 Greyscale 100

Greyscale 256Greyscale 200

Lasgrad2.wmf



Laser Diode Pulse Positioning The laser pulse position (at the left side of the pixel, at the center, or at the right side) can also change depending on the location of the image pixel, so that the edges of characters and lines become cleaner. All the examples in the previous section (gradation processing) show the dot being reproduced at the left side of the pixel. In the example on the right, the machine reproduces a thin diagonal line. At the left edge of the line, the dot is on the right side of the pixel, and vice versa. In general, putting the pixel in the center gives better results for photo mode.

a133d590.wmf

a133d589.wmf



Edge Smoothing (Copiers and Printers) When binary picture processing mode is used, there are only two possible grey scales, black and white. With this process, sudden changes from black to white mean that there might be jagged edges in the image. Smoothing attempts to remove these edges. Using laser pulse positioning, dots on the left side of black areas are made with only a portion of the pulse width, and these dots are moved to the right side of the pixel. In a similar way, dots on the right edges are narrower, and at the left side of the pixel.

a231d529.wmf



Smoothing (Fax Machines) The resolution for printing depends on the resolution that was used for scanning; this is informed in the set-up protocol. It also depends on whether or not smoothing is switched on. Smoothing is a digital processing technique that improves the resolution of the received message, reducing jagged edges on characters. Smoothing will change some bits from white to black, or vice versa, to round off jagged edges. A simple example is shown in the diagram. If the image from the other end is in standard mode (8 x 3.85 dots/mm) and smoothing is on, the data is smoothed as shown in the diagram to give an effective resolution of 16 x 15.4 dots/mm. If smoothing is off, the same dot is printed twice across the page, and the same line is printed four times down the page. If the message was scanned in detail mode (8 x 7.7 dots/mm), and smoothing is on, the CPU smoothes the data to give an effective resolution of 16 x 15.4 dots/mm. If smoothing is off, the same dot is printed twice across the page, and the same line is printed twice down the page.

Original Transmitted Image (e.g., 8x 3.85)

Received Image (8 x 3.85) Smoothed Image (16 x 15.4)

Smooth1.wmf



Fax machines that can print large numbers of gray scales can take advantage of that also.

Example: Models A639/A804 When the fax unit prints a received fax image, the fax board converts the data into 400 x 400 dpi, 16 x 15.4 l/mm, or 15.4 x 16 l/mm (image rotation) resolution, and smoothes the image using the 64 gradation levels + 3 laser pulse positions format used by the base copier.

A

200 dpi

200 dpi

400 dpi

400 dpi

Received Image Calculated Patternfor pixel "A"

Printed Image(Smoothed)

200 dpi

100 dpi

400 dpi

400 dpi

Received Image Printed Image(Smoothed)

A

Calculated Patternfor pixel "A"

A194D504.wmf



Print Density Adjustment (Fax Machines) In some fax machines, the laser pulse width depends on the mode (copy or fax) being used, the image density setting, and whether halftone is being used.

Example: Model H515 Mode Normal Lighten Darken

Normal Copy Mode Halftone

80 % 40 % 160 %

Normal 100 % 40 % 160 % Fax Mode Halftone 20 % 20 % 100 %

To change the pulse width, the duty cycle of the laser pulse is changed. For example, to make the print density 40% of normal, the laser is only kept on for 40% of the normal duration for each pixel.



Toner Saving In some machines, toner consumption can be reduced by omitting dots, as opposed to the use of a recycling mechanism or by adjusting development bias. In toner saving mode, the image data is filtered through a matrix. The following example shows the principle. 1st line 1 0 1 0 1 0 1 0 1 0 . . . . . 2nd line 0 0 0 0 0 0 0 0 0 0 . . . . . 3rd line 0 1 0 1 0 1 0 1 0 1 . . . . . 4th line 0 0 0 0 0 0 0 0 0 0 . . . . .

(1: Actual data printed, black or white; 0: Always a white pixel) In toner saving mode, the machine prints a black pixel whenever the data changes from white to black in the main scan direction. In this way, edges of black areas are printed more clearly. This feature is known as Edge Enhancement.

Enlargement (Fax Machines) Some fax machines enlarge the received image by increasing the duration of each pixel in the laser signal. For example, to enlarge the image by 200%, the duration of each pixel is doubled.



Thermal Printing

Thermal Head Overview Thermal printers contain a thermal head. A thermal head consists of a row of heating elements, which are basically just resistors. If a heating element is turned on, it will heat up. The heat from the element will make a dot on thermosensitive printer paper (fax machines), or melt the over-coating and polyester film layers to make a hole in a master (Priports). Whether an element turns on or not depends on the image signal for each pixel Fax machines have either 8 or 16 heating elements for each mm across the thermal head. Priport printers generally have 400 elements per inch. The diagram shows a 64-element assembly. A typical thermal head, having 4608 elements (see Thermal Head Specifications), would have 72 of these assemblies.

1 2 362

63 64

Vcc

ENR

LATCH

DATA

CLK

VHD

Vcc

Vcc

Vcc

Thead-1.wmf



Basically, the cpu clocks a line of data into a shift register in the thermal head. When the line is complete, the cpu sends a latch signal, then prints the line. Then the paper is fed forward one line, and the next line is printed in the same way. There is normally an independent power supply for the thermal head, which applies power to the thermal heating elements. For more details on how a thermal head works, refer to the chapter on standard components.

Typical Thermal Head Specifications Example: Model C210 Maximum Printing Width: 292.6 mm Number of Thermal Heating Elements: 4608 Density of Thermal Heating Elements: 400 dots/inch

Size of Thermal Heating Element: 45 x 60 µm Average Resistance of Thermal Heating Elements: 1520 to 2300 W Power Source: 15.1 to 18.6 V



Thermal Head Energy

Overview Voltage to the thermal head is applied in 16 V pulses. The energy applied to the thermal head is changed by changing the duration of the pulses. The duration of the pulses depends on the thermal head temperature and resistance.

Thermal Head Resistance The resistance of each thermal head is different. Therefore, after installing a new thermal head, always recalibrate the power supply unit according to the ratings on the thermal head cover.

Thermal Head Temperature The thermal head contains a thermistor, which detects the thermal head temperature.

Thead-2.wmf

Pulse Duration

Thermal Head Temperature

High Low

Short

Long



Maintaining Constant Element Temperature A thermal heating element may get too hot when there are consecutive black pixels in the sub-scanning direction. Conversely, a thermal heating element may not get hot enough to make a black dot or burn a hole in a master when there are consecutive white pixels in the sub-scanning direction. To remedy this, each thermal element receives data twice for one line. The data depends on the state of each pixel for the previous line. If the pixel at a certain position in the previous line was white, the first data for that pixel on the current line is black, to warm the element up. Then the actual black data is sent to the element. If the pixel at a certain position in the previous line was black, the first data is white, to cool the element down to prevent overheating.

Overheat Prevention The thermistor on the thermal head provides thermal head protection, preventing the thermal head from overheating when processing a solid image.

C222d599.wmf

Main Scan Direction

Previous Line Current Line 1st Output 2nd Output



Handling Pay careful attention to the following remarks when servicing:

• Remove any foreign materials from

the platen roller.

• Remove foreign materials.

• Do not touch the master filmsurface with bare hands.

• Connect and disconnect the connectorscarefully. Keep them horizontal andfirmly reconnect them.

• Do not touch the connectorterminals with bare hands, toprevent damage from staticelectricity.

Connector

Master

PlatenRoller

Thermal Head

PSU

MPU

• Adjust the voltage supplied to match thespecified value for the thermal head.

• Do not touch the surfacewith bare hands. If thisoccurs, clean the surfacewith alcohol.

• Do not damage theheating elements.

• There are some ICs insidethe metal cover. Do not pushthe cover down.



- Other Remarks - Avoid using the machine under humid conditions. Moisture tends to condense on the thermal head, damaging the elements.



Image Processing

Smoothing (Fax Reception) The principle behind smoothing is the same as for laser fax machines, except that incoming messages are smoothed to 8 x 7.7 or 8 x 15.4 dots per mm. If the message was sent in standard mode (3.85 lines/mm) and smoothing is switched on, the cpu smoothes the data to give an effective resolution of 7.7 lines/mm. This smoothing is shown in the diagram. If smoothing is disabled, the same line is printed twice, and the image may appear jagged. If the message was sent in detail mode (7.7 lines/mm), the data is printed unaltered.

Original Transmitted Image(e.g., 8 x 3.85)

Received Image (8 x 3.85) Smoothed Image (8 x 7.7)

Thdsmth1.wmf



Printing at Different Resolutions (Fax Machines) The printing density is 8 dots/mm across the page and 15.4 dots/mm down the page. To print in standard resolution (3.85 dots/mm down the page), each line of data is printed four times (the second of each pair of lines may be treated with smoothing - see the previous section). To print in detail resolution (7.7 dots/mm down the page), each line is printed twice. To print in fine resolution (15.4 dots/mm down the page), each line is printed once. However, as printing is slow, the thermal head energy may have to be increased so that the heat of the printing elements does not drop, causing a pale printout.

1/15.4 mm

1/8mm

OnePictureElement

Detail

A A A A

A A A A

B B B B

B B B B

Line1

Line1

Line2

Line2Line2

Line2

Line2

Line2

Standard

Line1

Line1

Line1

Line1

B B B B

B B B B

B B B B

B B B B

A A A A

A A A A

A A A A

A A A A

Fine

A A A A

B B B B

C C C C

D D D D

Line1

Line2

Line3

Line4

Thdsmth2.wmf



Reduction (Fax Reception) Normally, the transmitting terminal does reduction. However, if the receiving terminal can handle more than one roll width, it may reduce the incoming data in the following situation. If the message is received by substitute reception and the user installs a roll which is less wide than the image, the machine will reduce the data after it comes out of the memory. The reduction process is the same as that explained for transmission.

Main-scan Direction Image Position Adjustment (Priports) To adjust the image position of the original across the printout, the image can be shifted ± 5 mm in the main-scan direction using SP mode. The image is shifted in the main-scan direction by changing the relationship between the original main scan start timing and the master making main scan start timing.

C222D594.wmf



Ink Jet Printing

Ink Cartridges Ink cartridges consist of an ink sponge and a print head.

Example: Model H504 Ink Sponge [A]: This contains about 20 grams of ink, which is enough for printing about 550 ITU-T #1 charts.

Printer Head [B]: The printer head faceplate contains a row of 64 nozzles [C], spaced at a resolution of 360 dots per inch. Ink passes to these nozzles through a pipe [D], which contains a filter. Printing signals arrive at the printer head at the signal contacts [E]. Color ink cartridges contain a sponge for each color of ink.

[A]

[E]

[D][C]

[B]

Inkcart.wmf



Print Head Small heating elements force ink out of the nozzles.

Example: Model H505 Ink from the sponge is filtered at [A] to remove dust, and then passes to the nozzles through pipe [B]. When the head drive current flows through a nozzles heater plate [C], the ink at the plate boils. The bubbles formed [D] eventually join into one large bubble [E]. The bubble forces a drop of ink [F] out of the nozzle. Head drive current stops before the bubble is fully formed. The remaining heat of the heat plate completes the bubble. The plate cools by the time the ink drop is ejected, and fresh ink enters the nozzle from the sponge.

[A]

[B]

[C]

[D]

[E]

[F]H505D508 wmf



The nozzles are arranged in a straight line at intervals of 1/360 inch. There are 128 nozzles in the black ink cartridge. The color ink cartridge has a total of 136 nozzles: 24 yellow nozzles, 24 magenta nozzles, 24 cyan nozzles, and 64 black nozzles. The drive circuit is explained in detail in section 8 (Components).

Black Ink Cartridge Colour Ink Cartridge

1

128 136

1

Yellow 1~24Magenta 25~48Cyan 49~72Black 73~136

H505D509.wmf



Purge Unit This unit does the following. Capping puts a cap on the nozzles to prevent drying of the nozzle and ink leakage when the machine is not printing. Cleaning: During cleaning, the wiper unit wipes the face plate to remove paper fiber and ink, and the ink pump in the purge unit sucks old ink from the capped cartridge and fills the nozzles with fresh ink. In addition, the printer regularly ejects ink from all nozzles the cartridge to the purge unit to prevent ink from drying inside the nozzles and blocking them up. This is known as the maintenance jet function. The purge unit must absorb this waste ink. The machine operates the purge unit at certain times automatically (for example, just after switching on, at the start of each page, every 60 s during printing, after a certain number of dots have been printed, or after a certain amount of time that the printer has been inactive).



Example: H504 Purge Unit Control Gear: This gear [A] drives the purge unit wiper, cap, and pump.

Wiper Arm: This contains a rubber wiper [B] and the maintenance jet absorber [C]. The rubber wiper cleans the cartridges face plate from top to bottom every 60 seconds during printing and when it is time for cleaning. The maintenance jet absorber absorbs ink ejected from the nozzles when power is switched on, before the start of printing, and every 12 seconds during printing. The ink absorber removes ink from the rubber wiper and the maintenance jet absorber when the wiper arm goes down.

Cap: The cap arm with its rubber cap [D] advances and caps the ink cartridge when the wiper arm goes down. The rubber cap connects to the ink pump. During cleaning, this pump sucks ink from the cartridge and fills the nozzles with fresh ink. The capping mechanism pushes the rubber cap against the face plate of the cartridge, to stop ink at the nozzles from drying up or leaking out.

Pump: The pump unit [E] sucks ink from the rubber cap and passes it to the waste ink absorber [F] in the paper feed roller.

Purge1.wmf

[B][C]

Purge2.wmf

[A][D]

[F]

[E]



Carriage Drive Mechanism A motor drives the print head backwards and forwards across the paper. The carriage position is detected by counting stepper motor pulses, or by using an encoder, as in the following example.

Example: Model H905

The carriage drive motor [A] drives the print head carriage [B] through the belt [C]. The sensor [D], located under the carriage generates a pulse signal while it moves along the encoder [E] , so that the printer engine can detect the horizontal location of the carriage.

[A]

[B]

[C]

H905d004.wmf

[E]

[D]

H905d005.wmf



Ink End Detection Example: Model H505 To determine whether ink is present in the cartridge, the machine prints a black dot (known as the ink end mark) after printing the last line on a page. The ink end sensor reads the white level around the mark, and then it looks for the ink end mark itself. If the sensor cannot detect the mark, the machine determines that the cartridge is empty. Some machines have no ink end sensor. The volume of ink used is monitored during printing by counting the number of dots made. The machine displays a warning when the ink has almost been all used up.


Digital Processes Printer Interface Basics

Printer Interface Basics USB (Universal Serial Bus)

Introduction USB was designed to replace the serial and parallel ports, to provide a medium to high-speed port for a wide range of devices (such as mice, printers, speakers, digital cameras, & hard disks). Most computers and operating systems now support USB. There are many similarities between USB and IEEE1394. The computer acts as the host, and a chain of up to 127 devices can be connected to one host. USB has the following advantages over older parallel and SCSI interfaces: # Installation is very simple (no complex software or driver setup required). Just plug the device into

the USB socket (a small rectangular socket) on the computer. The computer will automatically detect it (plug and play); in some cases, the user may have to install driver software.

# No terminators, device IDs (like SCSI), jumper, DIP switch, or IRQ settings are needed.

# Speed is much higher than the parallel port.

# Devices can be plugged in and disconnected at any time, without having to switch off the computer. This is known as hot plugging.



USB 1.1 vs USB 2.0 USB 2.0 is a successor to the USB 1.1 specification. It uses the same cables, connectors, and software interfaces (USB 1.1 devices can be connected to USB 2.0 ports, and vice versa). USB 2.0 provides a maximum data rate of 480 Mbps (high speed). This is particularly suitable for high-performance peripheral devices such as high-quality video conferencing cameras, high-resolution scanners, and high-density storage devices. However, the lower speeds supported by USB 1.1 will be enough to satisfy most printing requirements. Mbps: megabits per second Click here to see a comparative data rate table for various types of interface.

Specifications Data rates: 1.5 Mbps (low speed), 12 Mbps (full speed), 480 Mbps (high speed) # Only USB 2.0 supports high-speed mode. The official logo is shown here.



USB Connectors USB transmits all data on a single pair of wires. Another pair provides power from the host computer to downstream peripherals. The USB standard specifies two types of connectors, type A connectors for upstream connection towards the host computer, and type B connectors for downstream connection to the USB device.

Type A connector

Type B connector



Printers and printer controllers inside MFP copiers have a type B receptacle.

Pin No. Signal Description 1 Power 2 Data 3 Data + 4 Power GND

Computers have a type A receptacle. Pin 4 is at the left, and pin 1 is at the right. To connect two PCs together, USB requires a special crossover cable.

11112222

3333 4444



Connecting More Than One USB Device to a Computer Up to 127 devices can be connected to each USB controller inside the computer. # Additional USB controllers can be installed inside the computer if required, by installing a card

inside the computer.

# Note that many computers have two or more USB ports. In some computers, these are connected to separate USB controllers (so in theory, 254 devices can be connected if there are two ports). However, in other computers, the USB ports are connected to the same controller, so only 127 devices can be connected in total.

# Devices connected to the same USB controller all share the same bandwidth. Devices connected to another USB controller inside the same computer do not share the same bandwidth as those devices connected to the first USB controller. If a USB device, such as an audio speaker system, is taking up a lot of bandwidth, it might be a good idea to install another USB controller inside the computer and use it for that device only. Otherwise, other USB devices on the same bus, such as printers, may not work so fast.



The maximum cable length between each device is 5 meters. # Using USB hubs (see the next page), chains of devices can be connected, as shown in the

following example. However, there cannot be more than six jumps between the PC and a device connected to a USB bus. In the following diagram, for example, there are three jumps between the computer and the video camera.



USB Hubs To connect a large number of devices to a computer, you can connect a USB hub to your computers USB connector. Then, typically, you can connect four USB devices to this hub. The diagram shows an example of a hub with four outlets. If you need more USB ports, you can make chains using hubs, but the total number of devices (excluding hubs) must not exceed 127. Also, as shown earlier, there cannot be more than 6 cables (jumps) between the PC and any device on the bus.

Power Supply to USB Devices The USB cable carries power from the computer. Devices that require a lot of power (such as laser printers) normally have their own power source, such as a mains power connection, and do not need to draw power from the USB connection. Generally, if a device needs to draw more than 500 mA, it has its own power source. Low-power devices such as mice do not have their own power source, so they need to get power from the USB connection. In these cases, the power will come from the computer. If such devices are connected to a USB hub, the hub should have its own power source (the one shown above does not have a power cable). If the devices connected to the hub have their own power source, then the hub does not need a power source.



Protocol USB is bi-directional, allowing data, commands, and queries to flow both ways between computer and peripheral. Just after the host computer is switched on, it checks what is connected to the USB controller and assigns an address to each device on the USB bus. New devices can be connected without switching the computer off; whenever a new device is connected to the bus, it is allocated an address immediately. The computer also needs to determine what type of signalling each device will use to transfer data. There are three types: # Bulk: Printers use this mode. The printer receives the data in packets, which are checked for

errors.

# Isochronous: This mode is used by devices that require data transfer between host and device in real time, without interruption. An example would be a set of audio speakers. There is no error correction in this mode.

# Interrupt: Used by devices that do not send a lot of data, such as a USB mouse.



How does the USB controller inside the computer allocate bandwidth? The controller assesses bandwidth demands whenever it checks what is connected to the bus. The available bandwidth is divided into frames of 1-millisecond duration. During each frame, isochronous and interrupt devices get whatever bandwidth they need These devices are allowed to take up to 90% of the total bandwidth that is available. Bulk mode transfers and data flow control protocol requirements use what is left. From this, it can be seen that connecting isochronous devices to the same USB controller as a printer can result in a loss of output speed. This could be a particular problem for USB 1.1. However, with the wide bandwidth available with USB 2.0, printing should still be fast enough for most users.



Connecting an MFP Product using USB This section explains how this company implements USB in its printers and MFP products.

Connecting Up Just connect the printer to the computer using a USB cable, either directly or through a hub (or chain of hubs). There are no settings to make on the computer or the printer. Note that if either the computer, hub, or printer have only a USB 1.1 card, the maximum data rate will be 12 Mbps. 480 bps (high speed) will not be possible:



Operating Systems Supported by Ricoh Products # USB 2.0: Windows XP (Home Edition/Professional), Windows 2000

(Professional/Server/Advanced Server) ! This may change depending on future support by Microsoft and Apple for USB 2.0.

# USB 1.1: Windows 98 (Second Edition), Windows Me, Mac OS 9.x, X (Classic Mode) ! Mac OS X (Native Mode) and Mac OS 10.1 are not supported. ! For Macintosh OS, only the built-in standard port is supported. ! 'USB Printer Support' is required for USB printing on Windows 98 (Second Edition) or

Windows Me. It is included on the CD-ROM for the printer. Follow the operating instructions.



Remarks concerning USB # The machine does not print reports specifically for USB.

# Using USB, the printer can only be connected to one computer.

# After starting a job using USB, do not switch the printer off until the job has been completed. When a user cancels a print job and data transmitted to the printer has not been printed at the time of cancellation, the job will continue to print up to the page where the print job was cancelled

# When the printer controller board is replaced, the host computer may recognize the machine as a different device.

# When printing from a Macintosh, PDL emulation may not be switched automatically. Please use the printer user tools to specify the PDL that will be used.

# Bi-directional communication is supported by the RPCS and PCL drivers. The condition of the paper trays and items in the Accessories tab of the printer driver can be monitored from the computer using a software utility such as SmartNetMonitor.



Related User Tools and SP Modes

Data Transfer Rate

This adjustment has two settings. The Auto setting allows the machine to use either high-speed mode (480 Mbps) or full speed mode (12 Mbps) depending on the USB bus speed. The Full speed setting restricts the machine to full speed (12 Mbps). The 12Mbps-only setting may be used for troubleshooting if data transfer errors commonly occur using the high-speed mode. Example: G081 series SP mode 5-844 User Tools Host Interface Menu

Do not change any other service mode settings unless instructed otherwise, or the machine may be out of compliance with local regulations



IEEE 1394

Introduction IEEE1394 supports data transfer rates of up to 400 Mbps. It was originally developed by Apple. # Apple uses the name FireWire for IEEE1394 products. The

FireWire logo is shown here.

# Other companies use other names, for example, Sony uses I-Link.

The concept of IEEE1394 is very similar to USB. # It allows a lot of devices on the same bus (up to 63 can be

connected to the same bus).

# No terminator or device ID, or dip switch/IRQ/jumpers to adjust

# Hot plugging

# Plug and play

# Provides power through the cable



IEEE1394 was developed before USB, and was for a long time much faster than USB. # IEEE1394 has a maximum data rate of 400 Mbps, and USB 1.1 has a maximum rate of 12 Mbps.

# USB 2.0 has a speed of 480 Mbps, so there is currently not much difference between USB and IEEE1394.

# However, the IEEE1394 specification has been upgraded to IEEE1394b, which allows speeds of 800 Mbps, and using fiber optic cables, up to 3.2 Gbps.

# Click here to see a comparative data rate table for various types of interface.

The main difference from USB is that IEEE1394 is a peer-to-peer technology. # This means that there can be more than one computer on the same IEEE1394 bus. Because of

this, more than one computer can share the same printer. This is not possible with USB. For USB, there can only be one computer in the bus.

# Also, two devices can communicate without a computer; for example, you can copy from a camcorder to a VCR, or print a scanned image directly, without sending the data through a computer.

# Computers can also be connected together to form a high-speed network for copying files. No special cable or hardware is required to connect computers together.



Specifications IEEE1394-1995 supports data rates of 100, 200, and 400 Mbps (megabits per second) over a cable length of 4.5 m (15 ft). # These speeds are actually 98.304, 196.608, and 393.216 Mbps. The figures are rounded up to

100, 200, and 400.

IEEE1394a-2000: Introduces improvements to the signalling protocols, to improve efficiency. IEEE1394b: Includes more improvements, and supports data rates of 800, 1600, and 3200 Mbps. There is also support for long-distance cabling of up to 100 m. There is full backward compatibility with IEEE1394-1995 and IEEE1394a-2000.



Data Rate Comparison Table

Technology Maximum Throughput

Serial Port (RS-232C) 230 Kbps Parallel Port (Centronics) Standard: Up to 100 kbps

With ECP or EPP: Up to 2.5 Mbps USB 1.1 1.5, 12 Mbps USB 2.0 1.5, 12, 480 Mbps IEEE1394a 100, 200, 400 Mbps IEEE1394b 800, 1600, 3200 Mbps Ethernet 10 Mbps, or 100 Mbps IEEE802.11b 11 Mbps Bluetooth 720 kbps

bps: bits per second



Connectors and Cables Six-pin: Four pins are for two twisted pairs, for a transmit-receive connection. The other two pins are for power (8-40V, 1.5A). Used for devices that need AC power, such as printers and external disk drives. The following diagrams show a cross-section of a six-pin to six-pin cable, and a view of a six-pin socket of the type commonly found on IEEE1394 interface boards. Four-pin: Data only; does not carry power. Used for camcorders and small portable equipment.

Pin No. Signal Description 1 Cable Power 2 GND 3 Receive strobe 4 Transmit data 5 Receive data 6 Transmit strobe

Pin 1

Pin 6



Do not connect a 4-pin device between the device that supplies power to the bus and a device that needs to draw power from the bus. Including 4-pin devices in the middle of an IEEE1394 chain means that power is not carried to the units further along the chain, so it may not be convenient for some users. In the example below, device A supplies power to the bus. Device D is a 4-pin device. Devices to the right of D in the diagram will not be able to get power from the bus, unless one of them is able to supply power from its own main power inlet through to the bus in a similar manner to device A.

If a device is connected to the bus with a 4-pin cable, it must have its own power source, such as batteries or a main power cable. However, using the 6-pin cable for battery-powered devices like video cameras ensures that the batteries are not drained while downloading data to the computer.



Here is an example of an IEEE1394 cable with a six-pin connector at one end and a four-pin connector at the other. The cable length is limited to 4.5 m (15 ft). However, chains of devices can be connected, and there can be up to 16 jumps between the devices on the bus. Up to 63 devices can be connected to an IEEE1394 network. The reason for the 4.5 m limit on cable length and the 4.5 x 16 m (72 m) total bus length is signal attenuation. At the high speeds of IEEE1394, the signal would be attenuated too much if the cables were longer.



IEEE1394 Bus

Topology: Chains and Trees # The drawings give three examples of how a

printer containing an IEEE1394 card ports can be connected up. The ports are repeaters, allowing data to be passed on to the next device on the bus.

# The first example shows the printer connected to two computers; one on each port. The result is a chain of three devices, with a computer at each end and a printer in the middle.

# The second example shows one port on the printer being connected to a string of computers. The net effect is a chain of five devices, four computers and one printer.

# The third example shows a hub being used. Branching using hubs allows us to get up to 64 devices on the same bus, in a tree structure.

# Some rules must be followed, as explained below.



Rules # Up to 64 devices on each bus

# There must be no loops in the bus

# Max cable length between nodes: 4.5 m

# Max. number of cables between the ends of a bus: 16 ! Each cable is also known as a hop or jump.

Nodes # Each device on the bus is called a node.

# A device can contain more than one node.

# Each node can contain more than one port, allowing nodes to be chained together. Each port acts as a repeater, passing data packets on to other nodes on the bus. ! Optional IEEE1394 boards for printers and MFP copiers commonly have two ports, so that

another device can be connected after the printer, forming a daisy chain. See the previous page.

! If the six-pin cables (carrying power for the physical layer signalling) are used, the repeater functions take place even if the node is switched off.



# On each bus, there is a root node, which controls the bus and manages the resources. This root node is often a 1394 interface board inside a PC.

# During a process called tree identification, the topology of the bus is determined. Each node is assigned an address, and the device that will be the root node is decided. It is also possible to force a particular node to become the root.

# Tree identification is done every time a device is added or removed, or whenever the bus is reset (by switching the root node off/on).



Cable and Backplane Connections # There are two types of IEEE1394 bus: cable, and backplane. ! Backplane: Devices are plugged into a chassis, like boards plugged into a PC motherboard. ! Cable: Devices are plugged into a root node, in a branching configuration, as described earlier

# In the backplane environment, devices do not contain repeaters, and their physical addresses may be determined by their slot positions

# In the cable environment, physical addresses are determined every time the bus is reset or a device is removed or added.

# Because of these differences, a bridge is needed to connect these two environments.

Addressing # The IEEE1394 bus appears as a large memory space shared between all the devices.

# Each node occupies a certain address range of this memory space. ! Addressing is based on the IEEE1212 Control and Status Register (CSR) Architecture.



# The address is 64 bits. ! 10 bits are taken up by the network ID. This informs which IEEE1394 bus the signal is coming

from.

What do you mean, which bus the signal is coming from? There is only one bus, isnt there? In theory, there can be up to 1024 buses in one IEEE1394 network (the number of the bus is specified by the 10 bit network ID). Two or more buses can only communicate with each other if they are connected together using a device called a bus bridge. An example is shown below. The bus bridge isolates traffic in each IEEE1394 network.

Installing another IEEE1394 card inside a computer is also a way to make another bus.



! 6 bits are taken up by the node ID. This informs which device on the above bus the signal is coming from. As a result, up to 63 branch and leaf nodes can be connected to a single root node. The node ID is assigned automatically during tree identification.

! 48 bits are taken up by the memory address. This means that an IEEE1394 network can address up to 256 terabytes of memory in each node. This type of addressing views the devices on the bus as memory that can be accessed with processor-to-memory transactions.

In addition, each IEEE 1394 device has a unique identification code, similar to the MAC address on an Ethernet or IEEE802.11b interface card. The code for the IEEE 1394 device is called an EUI-64 code.



Protocol Overview

Isochronous and Asynchronous Transfer

Overview # Both of these modes of transfer are supported.

# The mode that is used depends on the type of device. For example, a camcorder will use isochronous transfer, and a disk drive will use asynchronous transfer.

# Isochronous transport guarantees transfer of data at a certain rate and at a certain time, without interruptions. Data is considered to be useless if it arrives late. There are no retries.

# Contrast this with asynchronous, in which data can be broken up at irregular intervals, and where reliability is more important than timing, and where there can be retries if errors occur.

# Isochronous transport is ideal for devices such as video devices that need to transfer high levels of data within certain time constraints. For example, multimedia requires isochronous transport so that data is delivered as fast as it is displayed and so that the audio is synchronized with the video.

# In each IEEE1394 packet, bandwidth is allocated for both asynchronous and isochronous transfer. Up to 80% of a packet can be allocated to isochronous transfer.



Isochronous # Broadcasts to channel numbers, not specific addresses

# No error correction or retransmission

# Time-critical applications, or applications that are tolerant of errors, such as linked video and audio

# Bandwidth and latency are guaranteed ! The isochronous resource manager (often the same device as the root node or bus manager)

allocates resources for a device wishing to make an isochronous transfer. Up to 80% of the bus bandwidth can be used for isochronous transfers. The amount a device can obtain depends on how many devices on the bus are also currently making isochronous transfers.

Asynchronous # Transfers to a specific node with a specific address

# Transfers are acknowledged, so error correction and retransmission are possible

# Applications that are not time-critical but are not tolerant of errors, such as printers and hard disks

# There is no guarantee of a specific amount of bandwidth on the bus.

# The max data block size for an asynchronous packet depends on the transfer rate of the device. ! 100 Mbps 512 bytes; 200 Mbps 1,024 bytes; 400 Mbps 2,048 bytes



Connecting an MFP Product using IEEE1394 This section explains how this company implements IEEE1394 in its printers and MFP products.

Cables Normally, the printer only uses the 6-pin connectors. Use 6-pin cables to connect the printer to the computer.

Number of Ports The IEEE1394 option normally has two ports. These ports are repeaters. In the diagram on the right, the printer is part of a single chain of five devices (four computers and one printer).

Data Speed IEEE1394 printer interface options still do not support IEEE 1394b, so the maximum speed is 400 Mbps.



Example of Use In the example shown opposite, traffic on the office LAN is reduced by connecting up heavy-duty printing workstations to the printers using IEEE1394 (up to 400 Mbps, as explained earlier). General office workers who do not have high-volume print jobs are connected up using the slower Ethernet LAN. The printers are shared by both sections of the office, and they contain Ethernet and IEEE1394 interfaces.

100100BaseBase--TT

オフィスオフィスオフィスオフィス系系系系オフィスオフィスオフィスオフィス系系系系IP o

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1394

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基幹系

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General Office

Heavy-duty Printing

IEE

E 1394



Two Ways to Set Up the Printer: SCSI Printing, and IP Over 1394

Overview

There are two ways for a manufacturer to implement IEEE1394 in a printer. # Implement SBP-2 (Serial Bus Protocol) and use the SCSI-2 printer command set: This is SCSI

Printing. Available for Windows 2000 or Windows XP.

# Use IP (Internet Protocol): This is IP over 1394. Available for Windows Me or Windows XP.

For each of these methods, the printer is plugged into the computer in exactly the same way, using the IEEE1394 cable (do not try to use SCSI or Ethernet cables and hardware). The daisy-chain or tree bus configuration is acceptable for either of these methods. Also, there can be a mixture of protocols on the same bus. For example, if a computer is connected to a printer using IP over 1394, the other devices on the same bus do not all have to use IP; some of them can be using SBP-2 based signaling (such as a disk drive, or a printer set up for SCSI printing). If using IP over 1394, the user must make additional settings to allow the IEEE1394 interface to use IP protocol. Normally, SCSI printing and IP over 1394 cannot both be enabled at any one time. Select either one, using a user tool. Check the documentation for the product for details.



SCSI Printing

- Advantages - The main advantage of SCSI printing is that it is easier to set up than IP over 1394. - Disadvantages - IP over 1394 is more flexible, and some applications cannot be used with SCSI printing, as we shall see later. - Operating Systems - Windows 2000 users must use SCSI printing. Windows XP users can use either SCSI printing or IP over 1394. - Setup - To set up the machine for SCSI printing, make sure that SCSI print is enabled in the user tools. - User Tools - Bi-directional SCSI printing in the user tools allows the status of the items in the Accessories tab of the driver to be monitored at the computer using a software utility such as SmartNetMonitor.



IP over 1394

- Advantages - IP over 1394 also allows scanning over IEEE1394. SCSI printing does not allow this. In addition, some document solutions applications such as Scan Router can work on an IP over 1394 bus, but not using SCSI printing. In addition, the use of TCP/IP allows the printer to be connected to local networks, other subnets, and even to the Internet.

Is it possible to connect a printer that uses IP over 1394 to a computer that is connected to an Ethernet LAN? Use of a 1394-Ethernet bridge or Media bridge (Windows XP) is not supported by GW products. Future products may support this.

- Disadvantages - With IP over 1394, Plug and Play does not work, and the user must make IP settings at the operation panel during installation. # However, Universal Plug and Play (UPnP) should allow the computer to find the printer. UPnP is

provided with Windows XP and Me, but with Windows Me, it is not enabled by default.



- Operating Systems - Windows Me users must use this method. Windows XP users can also use this method. - Setup - A Ricoh printer with an IEEE1394 board must have a separate IP address for IP over 1394; it cannot use its Ethernet IP address. In fact, as shown to the right, the subnet must be different, not just the IP address. Because of this, there are separate IP settings for IP over 1394 in the user tools. The user tool TCP/IP settings for the Ethernet connection will not be used for IP over 1394. # This specification may change in the future.

In addition, to set up the machine for IP over 1394, make sure that IP over 1394 is enabled in the user tools.



Comparing SCSI Printing and IP over 1394 SCSI Printing IP over 1394 Available Functions Printing Printing, Scanning PC Operating System Required

Windows 2000 Professional with Service Pack 1 Windows 2000 Server with Service Pack 1 Windows XP

Windows Me Windows XP

Protocol Used SBP-2 TCP/IP Bi-directional Communication

Yes Yes

Number of Hops 16 hops (Max.) 16 hops (Max.) Length of Cable 4.5m between devices (Max.) 4.5m between devices (Max.)

# If Service Pack 1 is not installed in Windows 2000, there can be only one SCSI print device

connected to an IEEE 1394 bus, and the client cannot install the printer driver without using an account with Administrator permission.

# Using IP over 1394 with Windows Me: Additional software may be required, such as SmartNetMonitor for Client. Check the documentation for the product.

# Using IP over 1394, some models support DNS, DHCP, and WINS, depending on the firmware version. Refer to the technical documentation for that model.

# When using the Scan to E-mail function on IP over 1394, an SMTP gateway may be required. Check the documentation for the printer.



Installing an IEEE1394 Option Extra memory may need to be installed in the printer/copier, or the IEEE1394 option will not work. Check your service or operation manuals to make sure. After installation, some settings need to be made. Check your training documentation and operation manuals for the product for details on the procedures to follow.

Remarks concerning IEEE1394 Options Note the following general points about IEEE1394 interface options. # The machine does not print reports specifically for IEEE1394. Print the Configuration Page during

installation to check that the machine recognizes the card.

# There is no spooler or print queue. If a computer tries to print using IEEE1394 while the printer is busy, the IEEE1394 interface card inside the printer will return a busy signal.

# After starting a job using IEEE1394, do not switch the printer off until the job has been completed. Although the printer may appear to be inactive, it may be in the middle of an IEEE1394 protocol exchange with the computer.

# When using IEEE1394, it is not possible to check the printer status (busy/idle) from the computer with a utility such as SmartNetMonitor. However, when using SCSI print mode, if bi-directional communication is enabled in the User Tools for IEEE1394, the condition of the paper trays and items in the Accessories tab of the printer driver can be monitored from the computer.



Troubleshooting Notes If there are problems when printing using the IEEE1394 interface, check the following. # Is the computer using Windows 2000 with service pack 1? If not, install service pack 1.

# Has the interface card been replaced recently? Each card has an individual address, similar to the MAC address in an Ethernet card. If the card was changed, the driver still looks for the old card. The new card is considered as another device and a new printer appears in the Windows Control panel. The new card must be configured in the same way as the printer that was replaced (the old printer icon in Windows Control Panel should be deleted).

# Is there a loop somewhere in the network? An IEEE1394 network must be a chain or a branched chain. There can be no closed loops. If there is a loop, just disconnect the devices and connect them up again in a chain. The bus will reconfigure itself.

# Try to find out where in the bus the problem is occurring. Test the machine one-to-one with the computer to determine if the printer is defective (when the printers interface cable is plugged in, the computer should see Printer Ready; when the cable is disconnected, the computer should see Offline).

# Does the device disappear soon after installation? If a device switches itself off because of the Energy Star settings, it may disappear from Device Manager. If this is a problem, adjust the Energy Star settings in the printer.



# After installing the printer in the middle of a daisy chain, is a device after the printer on the bus suddenly unable to get power? This might happen if you use a 6-pin to 4-pin cable to connect up the printer. The 4-pin connection does not carry power to the next device in the bus. Do not connect a 4-pin device between the device that supplies power to the bus and a device that needs to draw power from the bus.

# If the device is slow, there may be a low-speed device (e.g., 100 Mbps) partway along the chain. Low-speed devices must be placed at the end of the bus. Otherwise, 400 Mbps devices may be forced to communicate at 100 Mbps.

# Earlier IEEE 1394 host adapters are not OHCI compliant, and because of this they are not compatible with Windows 2000. Make sure that the IEEE 1394 board inside the computer is OHCI compliant.

Related Service Modes Do not change the settings unless instructed otherwise, or the machine may be out of compliance with local regulations



Related User Tools Already discussed in the SCSI Printing and IP over 1394 sections. Example: G081 series - Host Interface Menu - IEEE1394 Setup

Make sure that IP over 1394 and/or SCSI Print are enabled

To use IP over 1394, these values must be stored. They must be different from the TCP/IP settings used for the Ethernet network.



Bluetooth

Overview Bluetooth (logo shown opposite) is one of the two widely-used wireless LAN technologies. The other is IEEE802.11b. Bluetooth is a specification for short-range radio links between mobile PCs, mobile phones and other portable devices. It was designed for both voice and data communications. It aims for low cost and low power consumption. It can be thought of as a way to replace the cable between two devices. However, it can also be used to form small networks, as we shall see. In addition to connecting a computer and printer, Bluetooth can be used to network a wide range of domestic appliances, such as stereo equipment and headphones in a home entertainment system, and a cordless telephone to its base. The technology is based on radio waves, so the devices do not have to be in line of sight. They can be in different rooms, for example. There are no cables, and the user does not have to make any complex settings to get things working. In theory, if you have a Bluetooth device and walk up to another Bluetooth device, the devices will communicate automatically as soon as they are within range. The user does not have to press any buttons or input any commands. Devices can establish a connection when they come between 10 metres of each other. 10 metres is considered to be a short range, and this short range is due to the radio frequency power output of 1 mW, which is very low (some cell phones emit up to 3 W). However, it will go through walls. Higher-powered Bluetooth devices with a power output of up to 100 mW can have a range of up to 100 metres, but Bluetooth is mainly intended to work at low power.



Communication Speed The basic specification for printing is 720 Mbps (megabits per second). A Bluetooth network has a total capacity of 1 Mbps. Protocol overhead takes up about 20% of this. Voice: In a full-duplex (two-way) voice channel, such as a telephone, data can pass at 64 kbps. This is much more than enough to support a voice conversation. Data: In a half-duplex (one-way) data link, such as printing from a computer, Bluetooth can transmit at up to about 720 kbps in one direction, with 57.6 Kbps in the other. For a full-duplex data link, the speed is about 430 kbps in each direction. At 720 kpbs, Bluetooth is a lot slower than the other networking technologies discussed in this section. For example, IEEE802.11b, the other wireless technology, operates at 11 Mbps. However, an updated Bluetooth with higher data rates is being considered. Click here for a table of data rates for various printer interfaces.



Bluetooth Networks A Bluetooth network is known as a 'piconet'. Another term for this is a personal-area network (PAN). Devices are connected to each other in an ad hoc fashion. (Loosely translated from the Latin, 'ad hoc' means 'on the fly'). A Piconet can start with two devices connecting to each other, and can expand until eight devices are connected. The connection is peer-to-peer, but one unit acts as the master, and the others act as slaves. In addition to the seven active slaves, there can also be passive, or 'parked' slaves out in the piconet. These devices are not actively communicating at the moment, and enter a low power mode. Up to 255 slaves can be parked. Slaves can participate in different piconets, and a master of one piconet can be the slave in another. This is known as a 'scatternet'. Up to 10 piconets can form a scatternet. In a scatternet, the piconets are not all synchronized with each other.



The master allocates the slots for the various communications taking place on the piconet, to control timing and avoid collisions. The clock and frequency hopping sequence of the master device synchronizes all other devices in the Piconet (frequency hopping will be explained later). It also stores the ID codes of the slave devices. # Each device has a unique 48-bit ID code programmed into the ROM at the factory; this ID code

normally appears as six two-digit numbers, such as 00:04:76:c5:fe:18. It is also known as the Bluetooth Device Address.

# Each active device in a piconet is also given a 3-bit address called the Active Device address.

# The user can also store a name for the device that is easy to recognize when using Bluetooth PC software to browse the Bluetooth devices in the piconet; this is known as a friendly name.

In a piconet, the master can support up to three synchronous ('voice') links of up to 64 kbps. Any free slots in the bandwidth can be used for asynchronous ('data') links. There can be up to seven of these in a piconet (one master, seven slaves). Asynchronous links can be either point-to-point (from master to one slave) or broadcast from the master to all slaves. In an asynchronous link, the slave can only transmit when the master requests it. By connecting to a LAN access point, a Bluetooth device can also access LAN resources. However, if the LAN access point does not talk Bluetooth, the Bluetooth device will not be able to connect, unless it has TCP/IP.



Radio Frequency Control Frequency Hopping Bluetooth operates at 2.402 to 2.48 GHz. This waveband has been set aside by international agreement for the use of industrial, scientific and medical devices (ISM), and is license free in most countries. Many types of devices, such as cordless phones, microwave ovens, and baby monitors, can use these frequencies. Bluetooth breaks this waveband into 79 channels of 1 MHz width. # In Japan, it is different. The frequency range is 2.472 to 2.497 GHz, and Bluetooth breaks it into

23 channels of 1 MHz width. France and Spain also use different frequencies.

Communications between devices change frequency to another channel 1,600 times a second. In the diagram opposite, there are three devices on the network. Notice how the devices all simultaneously change to another frequency at regular intervals (1,600 times a second, or once every 625 microseconds). # Rapid frequency change helps prevent

persistent interference between devices, not only Bluetooth devices but other types of device using the same frequency range. Interference on a particular frequency lasts only a fraction of a second.

Time

Freq

uenc

y Channel 1Channel 2Channel 3



# The low power signal used by Bluetooth devices also reduces the chances of interference.

# In the same area, there can be several piconets, perhaps making up a scatternet. To reduce the chances of interference, each piconet hops frequencies differently. Even if there is interference, it will probably be only for 625 microseconds, and Bluetooth contains software to automatically sort out confusion.

# This frequency switching technique is called Frequency-Hopping Spread Spectrum (FHSS).

Each 625-microsecond interval is called a 'time slot'. # According to Bluetooth specs, the master transmits in even-numbered time slots, slaves in odd-

numbered time slots. Packets can be up to five time slots wide. Data in a packet can be up to 2,745 bits in length.



Bluetooth Profiles As stated earlier, a Bluetooth device will communicate with another automatically if within 10 metres. However, there are many different types of Bluetooth device, and because of this, there are a number of different connection protocols, known as 'profiles'. In order to work with each other, two devices must both be able to use the same profile. Here is a list of profiles. # Generic Access Profile

# Service Discovery Profile

# Cordless Telephony Profile

# Intercom Profile

# Serial Port Profile

# Headset Profile

# Dial-up Networking Profile

# Fax Profile

# LAN Access Profile

# Generic Object Exchange Profile

# Object Push Profile



# File Transfer Profile

# Synchronization Profile

# Hardcopy Cable Replacement Profile

# Basic Imaging Profile

Bluetooth devices also have a device type identifier to inform other devices on the network what type of device it is. Using this information, Bluetooth devices within range of each other can form piconets among themselves and start working together. For example, a computer and a printer will form a piconet, stereo equipment and a set of headphones will form another piconet, and a cordless phone and its base will form a third piconet.



Security Bluetooth provides for several types of security, and the Bluetooth management software used by your PC may implement some or all of these.

Authorization If somebody tries to connect to your piconet, there is an alarm or warning, and you can then check who it is on the screen (the User Friendly name and Active Device Address of the requesting unit appear). You can then allow or disallow the connection. This security is not foolproof, because the user of the requesting device can change the User Friendly name. The only way to be sure is to keep a record of the device addresses of authorized devices.

Authentication Similar to Authorization (above), but the requesting user has to input a password as well. Trusted devices can be allocated a link key, so that they do not have to keep inputting the password. Such devices are authenticated automatically, without needing operator intervention.



Encryption Bluetooth specs also allow some form of encryption using keys. It is thought to be adequate for most users, but those with high security requirements will need to use stronger algorithms. In addition, not all Bluetooth devices support encryption. If a Bluetooth device requests encryption but the other device does not have this feature, the communication may terminate unexpectedly.

Withdrawing the Availability of Services If a Bluetooth device offers more than one service, the user can disable some of them to prevent unauthorized access. However, this is a bit severe, because nobody can use these services in this case. So, Bluetooth provides for different passwords to be allocated to each service if required.



Connecting an MFP Product using Bluetooth This section explains how this company implements Bluetooth in its printers and MFP products.

Installing a Bluetooth Option To connect to the printer, follow the instructions provided with the computers Bluetooth card.

Operating Systems Supported by Ricoh Products There are no limitations on operating system. If there is a driver for the operating system, the printer can be used with Bluetooth.

Bluetooth Profiles Supported by Ricoh Products Three profiles are supported. Communication from a PC must take place using one of these profiles. Serial Port Profile (SPP) # The printer shown by a Bluetooth search is connected to the serial port of the PC for printing.

Hardcopy Cable Replacement Profile (HCRP) # The printer shown by a Bluetooth search is connected to the Bluetooth printer port of the PC for

printing. This port is installed on the PC with the utility that comes with the PCs Bluetooth card.



Basic Imaging Profile (BIP) # BIP is direct printing from a remote device without a printer driver. PostScript 3 may be required

for this profile to be effective.

Notes # HCRP supports Bi-directional communication, but SPP does not.

# HCRP is supported by Windows XP with the Service Pack 1 supplement.

Limitations on the Number of PCs that can Connect to the Printer # In brief, up to 3 PCs can connect to the printer at the same time.

# There cannot be more than one PC-to-printer connection using the same profile. For example, if a PC has connected using SPP, any other PC wishing to connect at the same time will have to use HCRP or BIP. SPP will only become available after the original PC has disconnected (or has been refused access for security reasons).

# Within the same piconet, only one computer can connect to the printer. This is because in the computer-printer relationship, the computer must be a master device, and a piconet can only have one master device.

# However, a PC from another piconet can connect to the printer. In this case, it must be using a different protocol from the printer that is already connected.



Security Features

Public and Private Mode

This can be set up either using a service mode or by the user (Telnet or Web Browser; refer to the operation manual for the product). Public mode (default setting): # The printer can be found by Bluetooth software on the PC. The printer is shown by its model

name and Bluetooth active device address.

Private mode: # The printer cannot be found by Bluetooth software on the PC. However, if the printer is specified

using the PCs Bluetooth card, the printer can be used even if it is in private mode.

Password

The printer contains a password made up of the last four digits of the printer's serial number. If the Bluetooth software in the PC is using a high security mode, this password will have to be input whenever printing to that printer. However, at the moment, there is no high security mode option built into the printers to force the password to be input, so PC users can sidestep this by changing their security mode to a lower setting. This limitation may be addressed in the future. So for now, to ensure security at the printer side, use the Private mode mentioned above.



Troubleshooting Notes If the printer does not print, try the following: # Restart the computer and printer.

# Transmissions between the client PC and the printer can be blocked by obstructions. Move the printer and/or computer.

# If throughput is lower than expected, make sure that no IEEE 802.11b or other Bluetooth devices are in use. There may be some interference.

# Make sure that the versions of Bluetooth used by the printer and computer are the same. A device running Bluetooth 1.1 may not be able to work with a device running version 1.0.

# Make sure the printer you want to use can be found by the computer's Bluetooth software, and that the printer port has been set up correctly for the printer as described in the documentation for that software.



Related SP Modes Public and Private Mode: See above Example: G081 series SP 5-851

User Tools - None



Other Questions Is anybody in charge? # The Bluetooth Special Interest Group (SIG) controls the Bluetooth specification. The SIG started

off with several leaders in telecommunications and computing, namely Intel, Ericsson, IBM, Toshiba, and Nokia. Other companies have since joined.

# In addition, the IEEE 802.15.1 standard is based on Bluetooth 1.1.

# Compatibility between Bluetooth 1.0 and 1.1 devices is poor.

Why 'Bluetooth'? # Scandinavian companies have been important in developing wireless technologies, and have

played a major role in setting up Bluetooth. In respect of that, this technology was named after Harald Bluetooth, king of Denmark in the 10th century, who united Denmark and introduced Christianity into that country.

Before wireless LAN technologies were developed, infra red ports (IrDA) were commonly seen on laptop computers. Why was an effective printing technology not developed from this? # The main reason is that these infra red ports emit a beam of light in one direction, and this

requires that the ports on the communicating devices point towards each other exactly. This also means that only two devices can communicate with each other; there cannot be a network of devices linked together at the same time.

# Also, there were incompatibility problems with some of the protocols used for IrDA.



Bluetooth vs IEEE 802.11b Why do we have two wireless technologies? Do they complement each other, or compete with each other? The following short series of notes addresses this in relation to printing. Distance # Bluetooth - 10 m (33.7 ft)

# 802.11b - hundreds of feet, but depends on the environment of installation (walls, metal objects, etc)

Application # 802.11b is more a LAN type application, with a full range of networking features

# Bluetooth more a point to point type application, allowing small-scale networking, but not enough features for corporate-scale networking

Speed # Bluetooth - 1 megabit per second bandwidth (700,000 bit per second throughput)

# 802.11b - 11 megabit per second bandwidth - throughput depends on distance - somewhat less than 11 megabit, but performance typically seems to be the same as a wired LAN connection.

# The throughput of Bluetooth is good enough for printing, but not for high throughput applications.

Cost # Bluetooth is lower. It also consumes less power than IEEE802.11b.



Ease of use # Bluetooth is much easier - 802.11b has more setup to do (like normal LAN management)

Conclusion # The two technologies are complementary. IEEE802.11b is more suitable for corporate networks.

Bluetooth is more suitable for home networks, and for use with PDAs and cell phones, but not for high-bandwidth devices such as digital cameras because it is too slow.



Interference between Bluetooth and IEEE 802.11b Networks

Symptoms If throughput is reduced on either or both networks, interference may be the cause.

Causes Bluetooth and IEEE 802.11b devices both use the 2.4 GHz band. However, IEEE802.11b devices communicate on a single channel, which limits the frequency output of an IEEE802.11b device to about a third of the 2.4 GHz waveband at any one time. Bluetooth devices, on the other hand, rapidly hop frequencies all over the 2.4 GHz waveband. So intermittent interference between these two types of device is very likely. IEEE802.11b stations check for radio activity before sending a frame. However, Bluetooth does not do this, and may begin transmitting at any time, even while an IEEE 802.11b station is sending. On both types of network, interference causes lost packets, requiring retransmission of data, and reducing throughput. In addition, IEEE802.11b throughput is reduced even more by the following factors (these factors do not affect Bluetooth): # IEEE802.11b protocol requires acknowledgement of reception for each packet. If

acknowledgement is not detected, the packet is resent.



# At the start of transmission, if Bluetooth interference is present, an IEEE802.11b transmitter may mistake the Bluetooth signals for carrier from another IEEE802.11b device, and think that the channel is busy.

Occurrence Interference happens only when Bluetooth and IEEE 802.11b devices transmit at the same time. Printing using Bluetooth will only cause radio activity for a short while, so an IEEE 802.11b network will only be affected temporarily, if at all. Serious problems are more likely to occur if there are large-scale Bluetooth and IEEE 802.11b networks in the same building. Also, Bluetooth devices only have a range of 10 metres, so if the IEEE 802.11b device is not nearby, interference is less likely. Studies show that interference is unlikely if the devices are more than 2 metres apart. Laptops with both Bluetooth and IEEE 802.11b cards may have problems, especially if the laptop is situated at the outer edge of the IEEE 802.11b network, where the signal is weaker.



Ways to Reduce Interference Limit the use of Bluetooth to applications that are only active for a short time, such as printing small documents, or synchronizing PDAs to computers. Make sure that IEEE 802.11b signals can be picked up clearly in all areas that need them. If the signal is weak, any Bluetooth activity nearby could cause interference. Wireless technologies in the 5 GHz band are becoming available. Critical devices that are experiencing intolerable interference could be moved to this waveband.



IEEE802.11b

Overview IEEE802.11b is a wireless LAN technology. It is more powerful than Bluetooth, but harder to set up. It is also known as Wi-Fi. The Wi-Fi logo shown to the right is attached to products that have been certified by the Wi-Fi Alliance (formerly known as WECA: Wireless Ethernet Compatibility Alliance), which is supervising compliance with the IEEE802.11b standard. Compared with Bluetooth, IEEE802.11b is faster and has a longer range. Also, IEEE802.11b devices can easily be integrated into existing Ethernet networks.

Communication Speed and Effective Range The top speed is 11 Mbps whenever possible. The speed automatically falls back to 5.5 Mbps, then 2 Mbps and finally down to 1 Mbps if there are communication problems caused by interference or low signal strength. This means that speed can fluctuate, but data transfer is reliable. The range depends on the communication speed, as shown below.

11 Mbps 100 m 5.5 Mbps 200 m 2 Mbps 270 m 1 Mbps 400 m



However, these figures are for outdoor use. Indoors, the range depends on the layout of the building, and it is anything up to 100 m, but could be as low as 10 m in extreme cases. The maximum range also depends on which mode is being used (50 m for ad hoc, 100 m for infrastructure). Throughput also depends on network topology and load. However, there is typically no difference in performance compared to a wired connection. Note that some countries forbid the use of wireless LAN technology out of doors. Click here for a table of data rates for various printer interfaces.

Radio Frequency Control IEEE802.11b operates in the 2.4 GHz band, which is the same as Bluetooth. IEEE802.11b divides this waveband into 14 channels each of 22 MHz width. Devices on the same network must be tuned to the same channel. This method is known as DSSS (Direct Sequence Spread Spectrum). The channels that can be used depend on the region. # Europe: Channels 1-13 between 2412 and 2472MHz

# North America: Channels 1-11 between 2412 and 2464MHz

# Japan: Channels 1-14 between 2400 and 2497MHz

# Spain: 10, 11

# France: 10-13



To avoid interference with other radio frequency equipment, it is recommended to separate the frequencies by at least three channels. The diagram shows that a device using channel 11 may encounter interference if it is near a device using a frequency between channels 9 and 13. For example, if there are problems using channel 11 (default), try using channel 8. The machines that are using the same channel are called a BSS (Basic Service Set).

1 2 3 4 5 6 7 8 9 10 11 12 13Channel

MHz 2,412 2,437 2,462

25 MHz 25 MHz



What is Spread Spectrum Technology? This wideband radio frequency technique consumes more bandwidth than narrowband transmission, but produces a signal that is louder and easier to detect, if the receiver knows the parameters of the spread-spectrum signal. If a receiver is not tuned correctly, a spread-spectrum signal looks like background noise. There are two spread spectrum techniques: frequency hopping (used by Bluetooth) and direct sequence (used by IEEE802.11b).



IEEE802.11b Networks There are two types of IEEE802.11b network: ad hoc, and infrastructure.

Ad Hoc The ad hoc mode allows communication between each device in a simple peer-to-peer network. All devices must use the same channel. The channel can be set at the printers operation panel. The effective range between devices is about 50 m. There are two types of ad hoc mode. One is Ad hoc mode and the other is 802.11b ad hoc mode. In 802.11b ad hoc mode, in addition to having the same channel, machines must also have the same SSID (Service Set ID) in order to communicate; see Infrastructure mode for more on the SSID. 802.11b ad hoc mode is also called IBSS peer to peer mode (IBSS: Independent Basic Service Set). Some operating system environments and some wireless LAN cards only support one of these ad hoc modes.



Infrastructure Mode In infrastructure mode, devices can only communicate through an Access Point. Wireless LAN devices must use the same SSID (Service Set ID) as the access point in order to communicate. The SSID is a case sensitive 32-byte code. # Some device makers use a different name (NEC and Colega

call it ESS-ID; Apple and IBM call it Network name).

If a device has the same SSID as the access point, the channel will automatically be set to the same as the one used by the access point. If there is more than one Access Point, the client will connect to the access point that has the same SSID as the client. Printers generally only have one SSID; check the documentation for the product. Some access points support ANY mode, which allows devices to connect without comparing SSID codes, even if they have no SSID stored. If the access point is also connected to an Ethernet LAN using an Ethernet cable, devices on the wireless LAN will be able to connect to devices on this Ethernet LAN, and to a WAN or the Internet. The effective range between devices is about 100 m.

Access Point



Allowable Number of Users There is no limit on the number of users in an IEEE802.11b network. Also, if there are overlapping access points, people can move around a large area, such as a university campus, while remaining in contact with the network.

Advantages of Infrastructure or Ad Hoc mode Infrastructure mode # Access points provide access to Ethernet, WANs, and the Internet.

# Wireless LAN range is almost double.

# An access point can optimize traffic on the network.

Ad hoc mode # Easier to set up



Protocol

Protocol Layers IEEE802.11b provides only two layers. These are the physical (PHY) layer and the medium access control (MAC) layer. The data transport layer (such as TCP/IP, IPX/SPX, Apple Talk, NetBEUI) must be supplied by the computer or device separately.

Physical Layer

The physical layer describes how the data is sent between devices, as radio signals. This has already been discussed.

MAC Layer

This is a CSMA/CA (carrier sense multiple access with collision avoidance) protocol. Compare this with a CSMA/CD (carrier sense multiple access with collision detection) protocol such as used by Ethernet. # In a collision avoidance protocol, before device A sends a packet to device B, it checks to make

sure that no other device is transmitting. If the channel is busy, device A waits for a short while before checking again. Device A also asks device B if it is ready to receive, because device B may be already receiving from another device C (if device C is out of wireless LAN range from device A, then device A will not detect that device C is transmitting).



# A collision detection protocol cannot be used on a wireless LAN because collisions cannot be detected. This is because when a device is transmitting, the signal that it sends will drown out any incoming signal, and collision will not be possible to detect.

In addition to collision avoidance, acknowledgement and cyclic redundancy check routines are also used. Note that in contrast with IEEE802.11b devices, Bluetooth devices do not use a collision avoidance protocol, so they can cause radio interference.

Control of Infrastructure and Ad Hoc Modes In infrastructure mode, fixed access points control communication. When a client moves from the service area of one access point to another, the access points control the handoff to the next access point in a manner similar to a cellular network. In ad hoc mode, there is no structure to the network; there are no fixed points; and the devices can all communicate with each other. To keep order in this type of network, one device is elected as the master, while the other become slaves. This is similar to the Bluetooth piconet.



Security Several factors contribute to security, as described below.

Direct Sequence Spread Spectrum (DSSS) This type of radio frequency transmission technology is resistant to corruption, interference, jamming, and detection.

SSID (Service Set ID) Use of the SSID (either in 802.11b ad hoc or infrastructure mode) ensures that a device that does not have the same SSID as your network will not be able to gain access.

Encryption using the WEP (Wired Equivalent Privacy) Key

What is the WEP Key?

WEP is an encryption method using keys. There are 64 bit and 128 bit WEP keys. To unlock received encrypted data, the receiver must have the same WEP key as the sender.

Open and Shared Modes

There are also two modes, called Open and Shared modes # Open: Transmission data is encrypted.

# Shared: Handshaking protocol is also encrypted.



WEP Key Number

Some LAN card utilities allow more than one WEP key, and give a 'key number' to each WEP key. Most wireless LAN devices use 1 as the key number.

The WEP key and the WEP key number must be the same or communication will not be possible.

MAC Address The MAC (Medium Access Control) address is similar to the MAC address used for Ethernet devices. If infrastructure mode is used, access to the network can be limited at the access points using the MAC address. This type of security may not be available with some types of access points. This feature has to be enabled at the access point. Then, the supervisor of the access point must register the MAC addresses of devices that are allowed to use the access point.



Connecting an MFP Product using IEEE802.11b

Installing an IEEE802.11b Option In addition to IEEE802.11b settings, the data transport protocol must be set up properly, because IEEE802.11b does not supply a data transport protocol. Supported data transport protocols depend on the printer model and the operating system. Some common examples are TCP/IP, IPX/SPX, Apple Talk, and NetBEUI. For the following example, we shall assume TCP/IP is being used. On the computer and printer, both TCP/IP and IEEE802.11b settings must be made. It does not matter in which order these are done. However, if you wish to use telnet or a web browser to set up the printers IEEE802.11b settings, you must set up TCP/IP first. After installing the wireless LAN card, some parameters have to be programmed. Briefly, these are as follows: 1. First, input the following TCP/IP settings at the printers operation panel: IP address, Subnet Mask,

Gateway Address, DHCP, Frame Type (NW), and Active Protocol. ! Example: G080 printer

Use the User Tools Host Interface Menu Network Setup Menu ! Basic TCP/IP concepts are not covered in this section of the manual.

2. Make sure that the computer has its TCP/IP settings stored correctly. ! The IP address must be on the same subnet as the printer.



3. At printers operation panel (user tools) and at the computer, set up the IEEE802.11b parameters. ! Communication mode for the PC and the printer must be set initially to the ad hoc mode, even

if you will use the machine in infrastructure mode. The default for the printer is ad hoc mode. ! The channel setting on the PC must be the same as for the printer. ! When using a WEP key, set 1 as the WEP key number.

Ricoh wireless products use 1 as a default WEP key number. ! If 802.11 adhoc mode is being used, some vendors utilities need an SSID of ASSID.

4. At the printers operation panel, set the LAN type setting (a user tool) to IEEE802.11b (wireless LAN). ! This is only necessary in models where the IEEE802.11b and Ethernet connections cannot

both be active at the same time. If the printer has both types of LAN card installed, one of them must be switched off with this user tool.

5. Try to ping the printer from the computer. 6. If you wish to use ad hoc mode, you have finished. Make a test print.

If you wish to use infrastructure mode, change the printers IEEE802.11b settings (WEP key, SSID, Channel number) to match those of the access point. Then make a test print.

Note: After TCP/IP contact has been established between PC and printer, you can change the printers settings with telnet (or a browser if the printer contains a web server such as Web Status Monitor).



Operating Systems Supported by Ricoh Products There are no limitations on operating system. If the wireless LAN card in the PC is supported by the operating system, the printer can be used over the wireless LAN interface.

Operating Modes Supported by Ricoh Products Infrastructure, ad hoc, and 802.11 ad hoc modes are supported. However, ad hoc is not supported with Netware. Only one SSID can be stored. The default is null. If the operating mode is 802.11 ad hoc, then the default SSID automatically becomes ASSID. In such cases, if the printers default SSID is not changed, the SSID of the PC using the printer must also be ASSID. The SSID can be set at the machines operation panel, or with telnet, Web Status Monitor, or Web Image Monitor. Some devices automatically change from ad hoc mode to infrastructure mode when the same SSID is used in ad hoc mode and infrastructure mode. If you wish to connect the printer to such a device, the device must have a specified SSID to use infrastructure mode and ASSID to use ad hoc mode.

Security Features Some models support 64-bit but not 128-bit WEP keys. Some models support both types. Check the documentation for the model. Normally, only one WEP key can be stored in Ricoh printers. Check the documentation for the model.



Troubleshooting Notes

General

1) Check the LED indicators on the wireless LAN card. ! Orange LED: Lit - IEEE 802.11b card is working

Off - No power If the IEEE802.11b (wireless LAN) is not selected as the LAN type in the user tools, it does not light, even if the printer power is on.

! Green LED: Lit - It is connected properly to a network. Blinking - The machine is searching for devices. Off - No link established

2) Check if IEEE802.11b is selected in the LAN Type setting in the user tools. 3) Check for interference. If a Bluetooth network is nearby, there could be some intermittent interference. If there is persistent interference, try changing the channel setting (there should be a separation of at least three channels between interfering devices). 4) Make sure that the computer and printer are communicating on the same channel. If the computer cannot use the channel used by the printer (some client PC software has limitations on the channels that can be used), then change the channel setting in the printer. 5) WEP settings must be the same in the printer and the computer (Enable/Disable, WEP key and WEP key number)



Ad Hoc Mode

Move the devices closer together Check that printer and computer are using the same ad hoc mode. If there are both ad hoc and 802.11 ad hoc devices in the network, communication may not work correctly. # Some operating system environments and some wireless LAN cards only support one of these ad

hoc modes.

If the connection mode is 802.11 ad hoc mode, check that the SSID of the communicating devices is the same.



Infrastructure Mode

Bring the machine closer to the access point, change the antenna position, or check for obstructions between the machine and the access point. Do the printer and access point have the same SSID? If the Access Point has enabled MAC address security, check that the MAC address table has the printers MAC address, and that the printers MAC address is correct. The Access Point probably has a list of wireless clients that are currently connected. If the printer is not in the list, the printer cannot connect. If the printer is in the list, the printers IEEE802.11b settings should be correct (however, the PCs IEEE802.11b settings may be bad, the settings at the access point may be bad, or the printers IP address setting may be incorrect). Check the wireless communication status (use a user tool, telnet, or a web browser if the product contains a web server such as Web Status Monitor). This feature is only available with infrastructure mode. The status is described on a simple number scale.

STATUS DISPLAY COMMUNICATION STATUS Good 76~100 Fair 41~75 Poor 21~40

Unavailable 0~20



Related User Tools and SP Modes

User Tools Example: G080 printer Maintenance menu

Host Interface menu Network Setup LAN Type

# Select either Ethernet or IEEE802.11b as the active network connection

# If you wish to use IEEE802.11b, select it with this user tool. Printing using the Ethernet LAN will be disabled

Check the wireless communication status (only works for infrastructure mode).



Host Interface menu Network Setup IEEE802.11b

Transmission mode (ad hoc or infrastructure)

Channel number used for communication; depends on the location of the machine, as discussed earlier

Communication speed



Host Interface menu Network Setup IEEE802.11b, continued

SSID

WEP key: After setting to active, enter the WEP key that will be used for encryption by the PC



SP Modes Example: G080 printer, SP 5-840

Do not adjust other SP modes, or the machine may not be in compliance with local regulations.

SSID

WEP key WEP key number (normally fixed at 1 in printers; this may change in the future) Type of WEP key (64-bit or 128-bit)


FFaaccssiimmiillee PPrroocceesssseess Fax Basics What is a Fax Machine? Facsimile, commonly known as fax, is used for sending written, printed, or graphic information from one location to another. The communication can be across the room or across the world. A simple block diagram of fax operation is on the right. Facsimile machines combine scanner and printer technology with telephone equipment to send copies to a remote location. There are three basic steps in a facsimile transmission. • A light source scans the writing and drawings

on the original, and converts the information into an electrical signal.

• This signal is sent over the telephone line to a receiving fax machine.

• The receiving machine converts the incoming signal into a copy of the original.

ORIGINAL

SCANNING

CONVERSION

TRANSMITTINGFAXMACHINE

TELEPHONELINE

PRINTING

CONVERSION

RECEIVINGFAXMACHINE

RECEIVEDFAXMESSAGE

--- ---- -- ---- ------- --- ---- ------ --- - - --- -

-- -- -- -- ---- -- -- --- -

-- ---- -- --- --

--- ---- -- ---- ------- --- ---- ------ --- - - --- -

-- -- -- -- ---- -- -- --- -

-- ---- -- --- --

Faxintro.wmf

Fax Basics Transmission Reception Fax Circuit Update Compression Techniques Modulation Techniques Protocol Faxing From a PC Fax Troubleshooting Common Fax Features


Group 3 Fax Communication Fax Basics

Facsimile machines can transmit alphanumeric and graphic characters. Anything that can be put onpaper, from handwritten notes to photographs, can be sent by fax.

Mechanical Processes

A fax machine contains a scanner and a printer. The mechanisms are basically the same as thoseused in copiers.

Data Path

This section outlines the path of data through the machine in transmission and reception modes.

ComponentsThe following components of the fax video data path are not used in copiers.

SAF Memory (Store And Forward Memory)

When a user stores a fax message in the memory for sending later or transmission to more than onedestination, the message goes into the SAF memory. Also, incoming confidential messages and’substitute’ receptions (data coming in when the printer is not working) are held in this memory.



Line Buffer

This memory buffer ensures synchronization of video data transfer between different components ofthe circuit. If the line buffer is too small, the scanner mechanism will have to keep stopping andstarting, leading to excessive noise. A line buffer size of four or eight lines is typical.

Data Compressor and Reconstructor (DCR)

This circuit compresses the data before sending it out over the telephone line. It also reconstructscompressed data coming in from the telephone line

ECM Memory (Error Correction Mode Memory)

ECM is an optional extension to Group 3 protocol that provides a more reliable way to send data overnoisy lines. Using ECM, data is assembled into protocol frames. ECM requires RAM for assemblyinto and extraction from protocol frames. This memory is the ECM memory.

With ECM, image data is arranged in protocol frames (256 bytes in each frame), and transmitted inblocks made up of 256 frames. Therefore, each block is 64 kbytes. Normally, one page ofcompressed image data can be sent in one block, but more than one may be needed if halftonemode was used when scanning the original.

Single Buffer and Double Buffer ECM Memory

Single Buffer (64 kbytes): This memory is only large enough to hold one block. After receiving a blockof compressed facsimile data from the remote terminal into ECM memory, the data is reconstructed



and printed. The next block cannot be received until printing has finished. The first block is deletedfrom memory after printing.

Double Buffer (128 kbytes): This memory can hold two blocks. While one block is being printed, thenext block can be received into the other half of the double buffer memory. This ensures continuousoperation, saving time and overall communication charges. In some machines with a single bufferonly, SAF memory or hard disk memory are used to provide double buffer capability.

ECM is explained in more detail in the Protocol section. For full details, see ITU-T recommendationT.30.

FIFO Memory (First-In First-Out Memory)

The FIFO synchronizes the transfer of video data to the modem (transmission) or from the modem(reception). It also acts as a buffer, ensuring that there is always some data for the modem to pickup, modulate, and send out.

The FIFO also has some unique functions, in addition to synchronizing data transfer from the cpu tothe modem, as explained in the Transmission section (see the part entitled Data Transmission).

Modem

During transmission, the modem converts the data into a form that can be sent out on the telephoneline in accordance with the appropriate ITU-T V-series recommendations; this process is calledModulation.



During reception, the modem converts incoming data into a form that the machine can work with; thisprocess is called Demodulation.

The term ’modem’ is derived from these two processes; MOdulation/DEModulation. The differenttypes of modulation encountered in fax machines are described in the Modulation section (for fulldetails see the ITU-T V-series recommendations).

Network Interface Circuits

The filters, relays, attenuators and other components in these circuits interface the machine with thepublic telephone network. These circuits ensure that the machine connects to the line and that itdials in the correct way. They also ensure that the machine and the network equipment do notdamage each other. Some of the components are included in an assembly called the “Hybrid IC”(HIC).

Voice Message Processor

This converts recorded voice messages from analog (audio) to digital for storage in the memory. Italso retrieves the message for memory when it is needed for sending out over the telephone line.

TransmissionThis section explains the path of data through the machine during transmission. The maindescription is for memory transmission with ECM. Following this main description are diagramsshowing the differences between memory transmission with ECM and the following modes:• • • • Memory transmission without ECM



• • • • Immediate transmission with ECM

• • • • Immediate transmission without ECM

Scanning

This is the same as for digital copiers. Faxmachine scanners either contain a CCD(Charge Coupled Device) or a CIS (ContactImage Sensor).

Data Processing

CCD and Analog Video Processing

This is the same as for digital copiers.

Digital Video Processing

This is the same as for digital copiers.

If the original is wider than the paper in theprinter at the other end, data will be deleted inthe main scan and sub-scan directions to makethe data fit on the paper at the other end. Thisprocess is known as reduction.

Txpath.wmf9 August 2003 Page 435


Storage to SAF Memory

After leaving the Video Processor, the data is compressed and then stored in the SAF memory.

The compression method used varies from model to model. A simple compression technique suchas MH gives fast data storage, but the data takes up more room in the memory. More complexcompression techniques such as MR or MMR compress the data more effectively so that lessmemory space is used, but they increase the scanning time.

If a line takes up more space after compression, it is stored in raw uncompressed format.

Retrieval from SAF Memory

When it is time to send the data, the data comes out of the memory into the cpu. The cpureconstructs the raw data, and passes it to the line buffer.

(Lines of data that were stored without compression go from the memory straight to the line buffer.

Compression

The cpu then compresses the data in accordance with the method agreed in the set-up protocol thatwas exchanged between the two machines.

ECM Data Frame Assembly

Using the ECM memory, the cpu assembles the data into ECM data frames, which are sent to themodem and the line.



Modulation

The modem converts the data to serial and modulates it.

Attenuation

The data then passes through an attenuator, which adjusts the tx level (this is the output power ofthe data signal). It then passes through a variable resistor on the NCU, which can be used to adjustthe tx level. The data then passes to the network.

Flow charts for the different transmission modes are given below.

Memory Transmission, with ECM

SAFMemory

ECMMemory

Modem AttenuatorGain

Control

LineBuffer

Compression

Reconstruction Compression

CPU

CPUCPU

VideoProcessor

LineBuffer

Txdata1.wmf



Memory Transmission, without ECM

Immediate Transmission, with ECM

SAFMemory


Control

LineBuffer

LineBuffer

Compression

Reconstruction Compression

FIFOMemory

CPU

CPU CPU

VideoProcessor

Txdata2.wmf

LineBuffer

Compression

ECMMemory


Control

CPUVideo

Processor

Txdata3.wmf



Immediate Transmission, without ECMCompression


ControlFIFO

Memory

LineBuffer

CPUVideo

Processor

Txdata4.wmf



ReceptionThis section explains the path of data through the machine during reception. The data paths forthermal printers and laser printers are explained separately.

The main description is for basic reception without ECM. Following this main description arediagrams showing the differences between basic reception with ECM and the following modes:

• Basic reception without ECM• Memory reception without ECM• Memory reception with ECM

Common Processes

Filtering and Demodulation –

Data from the line passes through a filter to remove unwanted frequencies. Then it goes to themodem, which demodulates the data.

Reconstruction

From the modem, the data goes to the SAF memory, where it is held in case the printer jams or runsout of paper or toner; after the user corrects the fault, the message will be printed out from thememory and no data will be lost.

The data coming from the modem is compressed data. From the SAF memory, the data passes tothe cpu where it is reconstructed using the line buffer.

After this, the path depends on the type of printer inside the machine.



Thermal and Ink Jet Printers

Smoothing

The cpu then smooths the data, to remove jagged edgesfrom the data. The resolution of the received data isupgraded into the highest that the printer can print; this istypically 8 x 7.7 dots per mm.

Printing

The cpu passes the data to the thermal head or ink jetprint head through the line buffer.

Modem

FromtheNetwork

SAFMemory

ECMMemory I/OPort

Filter

LineBuffer

ThermalHead

ThermalPaper

CPU

Rxpath1.wmf



Laser Printers

Page Assembly

The data then goes through the slave cpu to the pagememory. When a full page of data has been assembled inthe page memory, the data goes to the LIF (LaserInterface). If the page is too long for the paper in thecassette, the data is split into two pages and/or reduced inthe page memory.

Smoothing

The LIF smooths the data. Smoothing removes jaggededges, converting the resolution of the received imageinto the highest resolution that the printer can accept. Thisis typically 8 x 15.4 dots per mm or 16 x 15.4 dots per mmfor a laser printer.

Printing

The laser beam switches on/off in accordance with thedata signal, and forms a latent image on the mastersurface.Flow charts for different reception modes are on the nexttwo pages.

Modem

FromtheNetwork

Laser Diode

Copy Paper

PageMemory

SlaveCPU

Buffer

SAFMemory

ECMMemory

MainCPUI/OPort

Laser DiodeDriver

Filter

LineBuffer

LIF

Rxpath2.wmf



Basic Reception with ECM

Basic Reception without ECM

LineBuffer

MainCPUModem

ECMMemory

PrinterEngine

ECMDataExtraction

SAFMemory

Reconstruction

Rxdata1.wmf

LineBuffer

MainCPU

ModemPrinterEngine

FIFOMemory

SAFMemory

Reconstruction

Rxdata2.wmf



Memory Reception with ECM

Memory Reception without ECM

LineBuffer

MainCPUModem

PrinterEngine

ECMDataExtraction

SAFMemory

Reconstruction

Rxdata3.wmf

LineBuffer

MainCPU

Modem

PrinterEngine

FIFOMemory

SAFMemory

Reconstruction

Rxdata4.wmf


Group 3 Fax Communication Transmission

Transmission

Overview

This section explains the communication control circuits for transmission.

When they leave the factory, most machines that have memory are set up for automatic dialing andtransmission from memory. The main part of this section is based on the steps taken by this type ofmachine. Other modes, such as transmission without memory, send later, automatic dialing frombehind a PABX, and manual dialing will be explained at the end of this section.

Below, there follows a brief outline of the individual steps for memory transmission with automaticdialing. These steps are basically the same for most machines.

Document Detection—The user places the document in the feeder, and the CPU turns on thefluorescent lamp when it detects the document. This process is not described in this section.

Document Feed—The machine feeds the document through the scanner. This process is notdescribed in this section.

Video Processing—The machine scans the document, converts the scanned data to digital, andpasses it through the video processing circuits. This process is not described in this section.

Call Collision Prevention—After the document has been scanned, the machine checks whether afax message is coming in. (The machine cannot dial while a message is coming in.)



DC Loop Closure and Line Monitoring—If there is no incoming call, the machine closes the circuitbetween itself and the telephone exchange. The machine will monitor the line for dial tone and/or linecurrent if required by local conditions (this is required in some European countries).

Dialing—The machine dials the other party.

Signal Detection—The machine then waits for a signal from the other party before going into txmode, if required by local conditions (this is required in some European countries).

Data Transmission—The data passes from the memory out to the line through the modem andnetwork interface circuits.

Return to Standby—The machine returns to standby mode.

The circuits for European and Asian models are different from those for North American models.Because of this, two separate sections have been prepared.


Facsimile Processes Transmission

North American Models

Call Collision Prevention

Overview

After placing an original in the feeder, the user enters the telephone number at the operation panel'sten-key pad, then presses the Start key. The machine then scans the document and stores it in theSAF memory. The machine then prepares to dial.

Note: Remember that for transmissions that do not use the memory, the order of events is different.After the user presses Start, the document is fed partway into the scanner and the machinedials. Scanning and storing is done after the other end has been reached. See ImmediateTransmission for details.

However, before the machine dials, it must check whether another call is in progress or not, toprevent a collision of incoming and outgoing signals. If the machine detects that a call is already inprogress, it will wait until the line is clear before dialing.

There are two criteria for detecting whether a call is in progress.

1. Has a ringing signal been detected, or is a potential ringing signal still being analyzed?

2. Is the local loop with the local telephone exchange closed?

To understand this, we need to understand how a fax machine connects to a PSTN (Public SwitchedTelephone Network). This explanation begins on the next page. The explanation is based on networkconditions in the USA; details differ from country to country.



PSTN Circuit

DC Loop Overview

Every telephone or fax machine isconnected to a local exchange of the PSTNthrough a two-wire pair. One wire is called"Tip" and the other is called "Ring"; thesenames refer to the tip and ring parts of theplugs used in manual switchboards (inEurope, L1 and L2 are often preferred). Thistwo-wire circuit is known as the "dc loop", or"local loop".

Each telephone and fax machine contains aswitch which opens and closes the localloop. When the switch is closed, dcgenerated by the local exchange flowsthrough the dc loop. The voltage on the dcloop varies from area to area; for example,in the USA, it is about 48 V.

LOOPOPEN

LOOPCLOSED

Fax or Telephone

+

Fax or Telephone

+

Local Exchange

Local Exchange

Dcloopu1.wmf



DC Loop through Telephone

When the telephone is on-hook, the hook switchconnecting it to the local exchange is open, and dcfrom the local exchange cannot pass through thedc loop. However, the telephone's ringer isconnected (the ringer does not allow the dc fromthe exchange to pass, but allows the ac ringingsignal to pass).

When the handset is picked up, pressure on thehook switch is released, and the switch closes.Then, dc from the local exchange passes throughthe dc loop.

DialingCircuit

HookSwitch

Ringer

TELEPHONE(Simplified)

TIP

RING+

RingingSignal

Generator(20-47 Hz)

LOCALEXCHANGE

Dcloopu2.wmf



DC Loop through Fax Machine with External Telephone

Inside the fax machine, there are two components,called the Oh relay and the Di switch. These act asthe fax machine's hook switch.

When the machine is in standby mode (as shownabove), the Oh relay is set up so that the network isconnected to the external telephone (commonlyknown as the handset); in this set-up, the handsetcan be used as a normal telephone, as explained onthe previous page. The dc loop is open, because thehandset's hook switch is open. However, the ringingsignal detector in the fax machine and the ringer inthe handset are both connected to the line.

When the machine closes the dc loop, it switchesover the Oh relay to disconnect the handset from theline. Then it closes the Di switch to connect the faxmachine to the dc loop. The fax machine's CPU willbe able to detect the presence of dc by monitoringthe line current detector. Ringing

SignalGenerator(20-47 Hz) +

LOCAL EXCHANGE

+24V

FAXTERMINAL(Simplified)

RingingSignal

Detector

LineCurrentDetector

HandsetHook Switch

To/FromFaxCircuits

Dcloopu3.wmf

Di Switch

Oh Relay



Call Collision Prevention in Fax Machines

For 0.2 s after the user presses Start, the CPUmonitors the ringing signal detector and the linecurrent detector to check that the local loop hasnot already been closed (if the local loop hasbeen closed, there will be current on thetelephone line).

If a possible ringing signal is still being analyzedwhen the user presses Start, the CPU will wait for8 seconds, then check whether the signal is stillbeing analyzed.

The diagram shows the call collision preventioncircuits. The position of the relays in standbymode depends on the reception mode beingused. See Reception for diagrams.

Ringing signal detector: This circuit consists ofsome zener diodes and a photocoupler. If the voltage of an incoming signal is high enough, it turnson the photocoupler. Then, the CPU detects that its connection to the ringing signal detector hasbeen grounded.

Line current detector: This is a pair of photocouplers. The CPU detects line current when one ofthe sensor outputs is grounded; the output that is grounded depends on the polarity of the dc on theloop.

TIP

RING

RI

TI

Network

+24VS

RINGINGSIGNAL

LINECURRENT

LINECURRENT

HandsetCPU

Dcloopu4.wmf



DC Loop Closure and Line MonitoringAfter it has been confirmed that there is no possibility of call collision, the machine automaticallycloses the circuit between itself and the local exchange; this circuit is commonly called the dc loop, orthe local loop. Closing the dc loop is the fax machine's way of going off-hook before dialing.

In some areas, dialing cannot begin until the machine has checked for dial tone and line current. Thisis known as "line monitoring".

DC Loop Closure

The fax machine closes the dc loop after checking forincoming calls. If there is no incoming call, the cpucloses the dc loop by activating the Oh relay todisconnect the handset from the line. Then, after 5ms, it closes the Di switch to connect the fax machineto the line.

The cpu then waits for the 'PSTN wait interval' [A] ofabout 2 s before starting to dial.

OHRelay

Only if pulsedialingisused

DiSwitch

5ms

Dialling

[A]

Dcclus1.wmf



On the circuit diagram, curved arrows show therelays switching over from standby mode toclose the dc loop. The Di switch is aphotocoupler.

The standby position of the Oh relay dependson the reception mode selected. See Receptionfor details.

Note

PSTN wait interval: This can normally beadjusted by RAM address.

TIP

RING

RI

TI

Network

Oh Relay

DiPhotocoupler

+24VS

+5V

+5V

5

5

CPU

Handset

Dcclus2.wmf



Line Monitoring

Before starting to dial, conditions in parts of Europe require that the machine monitors the linecurrent detector for line current, and signals on the line for dial tone.

Therefore, in Europe/Asia models, the PSTN wait interval can be replaced by dial tone and linecurrent detection, if required by local conditions. (Dial tone and line current detection are alsoavailable in USA versions of some of the more complex models.)

Line Current Monitoring

Line current detection allows the machine tocheck whether the dc loop has been closed.If there is no line current, the dc loop may stillbe open.

The machine uses the following parametersto detect line current.

• Line current wait time [A]• Line current detection time [B]• Line current drop detection time [C]

[A] starts when the dc loop closes. [B] startswhen the line current first reaches the machine.

[B]

[A]

Line Current MonitoringStarts Here

[C]

Dcclus3.wmf



The machine checks for line current during [A]. Line current must be on the line for [B] or longerbefore it is recognized by the CPU. If the CPU has not recognized line current during the interval [A],the machine disconnects. However, if the line current has started but has not been on for [B] when[A] expires (as shown below), detection continues until it has been on for [B].

After starting [B], the machine continually checks the line current for interruptions. If any singleinterruption lasts for [C] or longer, the line is cut, [A] and [B] are reset, and the machine returns tostandby.

Dial Tone Monitoring

The local exchange sends a dial tone to inform the user thatthe exchange can accept a telephone number. Dial tonemonitoring allows the fax machine to check for this tonebefore dialing; if there is no dial tone, the exchange may notbe ready to accept a telephone number.

The machine uses the following parameters to detect dialtone.

• Acceptable frequency range• Dial tone detection time [A]• Reset time [B]• Continuous tone time [C]• Permissible drop time [D]

Dial ToneDetected

Dial Tone<[C]

>=[D]

<[D]

[C]

Dial tonefirst appears

[A]

DCLoopClosure

[B]

Dcclus4.wmf



[B] starts when the dc loop is closed. Dial tone must appear before [B] expires. If dial tone appearsjust as [B] expires, detection continues and the deadline at the end of [B] is ignored.

The machine detects a dial tone when the tone continues for [C] or longer without interruption. Also,[A] must have passed since the dial tone first appeared. Interruptions shorter than [D] are ignored.

Switching Line Monitoring On/Off

A nation that requires line monitoring has the necessary parameters programmed in the ROM; theyare normally activated when the country code (normally a bit switch setting) is set to the code for thatnation.

However, if required, line current and dial tone can be disabled; the way to do this varies from modelto model.

Similarly, in countries which normally have line monitoring disabled, line current and dial tonedetection can be enabled; however, the parameters for detection will have to be stored in theappropriate RAM addresses.

When line monitoring is disabled, the machine waits for thePSTN wait interval [A] before starting to dial.

Dial Pulses or Tones

[A]

LoopClosure

Dcclus5.wmf



Note

The following parameters can be programmed by RAM address.

Line Current MonitoringLine current wait time Line current detection timeLine current drop detection time Line current monitoring on/off

Dial Tone MonitoringAcceptable frequency range Dial tone detection timeReset time Continuous tone timePermissible drop time Dial tone monitoring on/off

OtherPSTN wait interval



Dialing

Overview

After the dc loop has been closed, the machine can dial. In automatic dialing mode, the machinedials in accordance with the number entered by the user at the operation panel, either in full, or as aQuick Dial or Speed Dial.

There are two types of dialing: pulse dialing, and tone dialing. The dialing method must match thedialing mode that can be accepted by the local exchange, or the machine will not be able to dial out.

The dialing method can be chosen by a user function in most countries.



Pulse Dialing

Pulse dialing was originally developed tooperate mechanical switching systems in thelocal exchanges.

The machine sends voltage pulses to the localexchange by interrupting the dc loop. It doesthis by opening and closing the Di switch. Eachdigit is represented as a different number ofpulses. For example, to dial a "2", the machinesends out 2 pulses.

The Oh relay remains fixed during dialing (itdoes not move until the machine returns tostandby mode).

The Di switch is a photocoupler.Photocouplers are compact and inexpensive.

Each digit of the telephone number is sent out as a pulse train. The cpu sends out the dial pulses byopening and closing the Di photocoupler on/off.

TIP

RING

RI

TI

Network

Oh Relay

DiPhotocoupler

+24VS

+5V

+5V5

CPU

Handset

Dialu1.wmf



The time that the Di photocoupler opens iscalled the break time [A] and the time that itcloses is called the make time [B]. Eachpulse sent out on the line is made byopening and closing the Di photocoupler.

A minimum pause [C] is required betweeneach digit, regardless of whether the userpressed the pause key while dialing.

Example: Dialing 43

Notes

Most countries dial in the same way (the number of pulses sent out [P] is the same as the numberdialed [N]). However, some areas require different types of pulse dial signals. For example, in Oslo,P must be 10 - N, and in Sweden, P must be N + 1. The required mode can be selected by bit switchadjustment.

Pulse dialing can be done at two rates: 10 pulses per second (pps) or 20 pps. If the local exchangecan only handle 10 pps dialing, the machine must not be set to dial at 20 pps. The dial pulse rate canusually be adjusted by bit switch.

Parameters A to C illustrated on the diagrams in this section are programmable.

For pulse dialing at 10 pps, the times stored in the NCU parameters are used as explained in thissection. However, at 20 pps, only half the values in parameters A and B are used, and three-quartersof the value in parameter C.

DiPhotocoupler

[C]

[A]

[B]

4 3ONHOOK

OFFHOOK

DCLoopClosed

Dialu2.wmf



Tone Dialing

Overview

Each dialed digit is sent out as a DTMF (Dual Tone MultiFrequency) tone, which is a mixture of two frequencies. Thefollowing diagram shows what frequencies are generated foreach digit on a typical telephone keypad. For example, a '5' isrepresented by a 770 Hz tone combined with a 1,336 Hz tone.

The DTMF tone frequencies are the same throughout theworld. They were carefully chosen so as not to coincide withother frequencies that may occur on the line.

In some types of telephone equipment, the DTMF circuitremains on line after the call has been connected. This allowsthe use of DTMF tones for giving orders to the remote terminal(e.g., extracting information from a remote database).

The advantages of using DTMF over pulse dialing are asfollows.

• Dialing is faster

• DTMF tone generation circuits are compact solid-state circuits

• There can be end-to-end signaling after call connection, as mentioned in the previous paragraph

Diale5.wmf



DTMF Tone Generation

The diagram shows how DTMF tones aregenerated in fax machines.

The cpu generates two square waves of therequired frequencies. These each passthrough a low pass filter to remove noise, andare added together.

In the attenuator, the DTMF tone isattenuated. The attenuation value is differentfrom that used for the attenuation of facsimiledata.

The DTMF tone is then amplified tocompensate for the signal loss between theattenuator and the telephone line. The tonethen passes to the line through the Di switchand Oh relay, which remain fixed during tonedialing.

To theNetwork

Filter

Filter

Adder Attenuator

CPU

Dialu3.wmf



Attenuation of DTMF Tones

The machine always uses permissive attenuation for DTMF tones, even if programmable attenuationhas been selected. (See Data Transmission concerning permissive and programmable attenuation.Programmable attenuation is only done in older models, some of which may still be in the field.)

Note: The DTMF tone attenuation value can be adjusted by RAM address. However, unlike theattenuation value for facsimile data, it cannot be adjusted using dedicated transmissionparameters or bit switches.

Timing

DTMF tones are sent out in accordance with thetiming shown in the diagram.

Note: The DTMF tone on time [A] and off time [B]can be adjusted by RAM address.

Pauses

If the user dials a pause using the Pause key, themachine waits for a pre-programmed interval before sending the next tone or pulse.

Note: The pause interval can be changed using a RAM address adjustment.

[A] [B]Diale7.wmf



Signal Detection

Overview

After dialing, the machine waits for the response from the other end. The response is usually either aCED tone, a busy tone, or a ringback tone. These tones are known as progress tones. Instead of aprogress tone, a protocol signal such as NSF or DIS may be detected at this time.

The received signal passes through two filters. A highpass filter (with a cut off of about 300 Hz) removes lowfrequencies, such as noise from the fax machine'spower supply, and a low pass filter (with a cut off ofabout 2100 Hz) removes high frequencies, such asnoise from overhead railway power cables.

The signal then passes to a programmable gainamplifier, which raises the signal level enough for themachine's hardware to analyze it. The minimum signallevel on the line will vary from country to country, sothe amplifier is programmable. For example, in typicalUSA models, the amplifier is set up so that signalsweaker than -53 dBm are not detected.

The amplified signal is converted to digital, then passed to the tone detector in the cpu.

FromtheNetwork

Filters

ProgrammableGain

Amplifier

A/DConverter

CPU

Sigdet.wmf



The incoming signal may determine whether or not the machine goes into transmit mode. Mostmachines have bit switch or other settings to determine when the machine goes into transmit mode.The choices are typically as follows:

• After dialing• After receiving NSF or DIS• After receiving CED

Note: The gain of the amplifier depends on the country code (the country code is selected by a bitswitch adjustment). However, the gain can be changed by a RAM address adjustment; in mostmachines, there are 4 possible values to choose from.



Busy Tone Detection

If the call has gone through and if the called terminal is already off hook (i.e., the other end is busy),the local exchange at the other end sends back a busy tone.

If the machine detects busy tone, it will disconnect the line. The number will be redialed (seeRedialing), unless the maximum number of redials have already been made.

If busy tone detection is disabled and the line is busy, the machine will hold the line until the ITU-TT1 timer (about 1 minute) runs out. So busy tone detection can reduce the amount of time themachine holds the line.

Transmitter Receiver

BUSYNetworkDIALLINGSIGNAL

BUSYTONE

LocalExchanger

LocalExchanger

Sigdet2.wmf



Busy Tone with Cadence

In many countries, the busy tone has acadence (a fixed on-off cycle), so themachine measures the on and off times ofthe received signal and compares them withvalues programmed in the RAM.

RAM addresses specify four permissiblelengths for each signal state. The machinefirst checks if the signal has a length withinrange 1. If it does not, then range 2 isselected, and so on. An example is shownto the right, in which the on-off timedurations are found to be within range 3.

Note

The following values are stored in RAM.

• Range 1, ON time Range 1, OFF time• Range 2, ON time Range 2, OFF time• Range 3, ON time Range 3, OFF time• Range 4, ON time Range 4, OFF time• The number of cycles required for detection (for example, a setting of 4 means that ON-OFF-ON

or OFF-ON-OFF must be detected twice).

Busy Tone

DetectionFlag

ON OFF ON OFF ON OFF

Out ofRange1

Out ofRange2

WithinRange3

(1) (2) (3) (4)

TwoCycles

WithinRange3

WithinRange3

WithinRange3

Sigdet3.wmf



• ON or OFF time tolerance (+/-), for ranges 1 to 4.• Acceptable signal frequency range

Continuous Busy Tone

In some countries, such as the UK, the busy signal is not a cadence. The busy tone must continuefor a certain time before the machine detects it.

Note: The minimum time required for continuous busy tone detection is stored in RAM.



Ringback Tone Detection

If the call has gone through and if the called terminal is on hook, the local exchange at the other endsends a ringing signal to the called party; at the same time it sends a ringback signal back to thecaller.

Ringback tone detection is always switched on in Austria. Ringback tone is detected if the ringbacktone is longer than the minimum ringback tone detection time (0.1 s), which is stored in RAM.


NetworkDIALLINGSIGNAL

LocalExchanger

LocalExchanger

RINGBACKTONE

NOREPLYYET

Sigdet4.wmf



- If the machine at the other end is a telephone -

When the phone rings at the other end, the transmitting machine detects ringback tone. The otherparty picks up the handset when the phone rings, and replaces it when there is no voice on the line.Then, the local exchange at the receiving end sends back a busy tone to the transmitter (this isnormal in Austria).

When the transmitter detects this busy tone, it immediately disconnects the line without waiting forthe ITU-T T1 time to expire. Ringback tone and busy tone were both detected on this call; in suchcases, the software in the transmitter disables automatic redialing for this number.

Note: In Austria, it is necessary to prevent a fax machine from redialing addresses for which the T1timer expired on the first attempt.

- If the machine at the other end is a fax machine -

In Austria, the receiving fax machine will close the dc loop after it has detected one ringing signal.(So, the ringback tone to the transmitter will be short, but not too short for detection.)

Immediately after closing the dc loop, the receiving machine will send CED. If the user at thereceiving end presses Stop after this, both machines will disconnect immediately.

The transmitter will not receive busy tone from the other end, as it has already disconnected, so thenumber can be redialed automatically.



Note

The ringback tone has the same frequency as the busy tone.

The only RAM address that must be programmed for ringback tone detection is as follows.Ringback tone detection time

CED Detection

If the receiver is a fax terminal in Auto Receive (Fax) mode, it will emit a 2100 Hz tone called CED.

This signal informs the caller that they have connected to a fax machine. CED is the high-pitchedtone that prompts the user to press the Start key when using Manual Dialing.

In automatic dialing mode, the transmitting fax terminal confirms CED detection when the CED tonecontinues for 200 ms or more. Then it starts to scan the document.



LocalExchanger

LocalExchanger

CEDTONE

FAXMODE

CEDTONE

Sigdet5.wmf



Data TransmissionThe data transmission circuit is shownabove. The cpu retrieves the data from theSAF memory, processes it, and passes it tothe modem. The modem modulates thedata to convert it into a form that is suitablefor transmission over the public telephonenetwork. The data is then attenuated to thecorrect signal strength for transmission.

The major steps are explained on thefollowing pages.

Processing in the CPU

The cpu retrieves the data from the SAFmemory and reconstructs it (if it wascompressed before storage into the SAF).The cpu then processes the data beforesending it to the modem. The signal to themodem is eight-bit parallel, with one bitrepresenting one picture element (unlessthe data was reduced—see the DigitalProcesses chapter for details on reduction).

To theNetwork

SpeakerVolume and

On/OffControl

Modem

ProgrammableResistorSelectSwitch

TIP

RING

Attenuator

SAFMemory

ProgrammableResistor

Attenuator

CPU

[B]

[A]

Tx-u.wmf



Compression

Compression reduces the number of bits in the data signal, and therefore the transmission time forone page.

MH, MR, and MMR compression are done according to ITU-T standards.

A proprietary procedure called EFC (Estimated Fillbit Control) may be applied to the compresseddata. EFC is not strictly a compression technique, but it improves the efficiency of data transfer bycontrolling the number of fill bits inserted by the transmitter at the end of each line of data (seebelow).

The data is compressed in accordance with the method agreed in the protocol between thetransmitting and receiving machines. In Group 2 and Group 1 modes, the data is not compressedbefore transmission.

Brief explanations of the different coding types follow. MH and MR coding are explained in detail inthe ITU-T recommendations for Group 3 facsimile.

MH—Every line is MH coded.

MR—Data is treated in blocks of 2 lines (in Standard or Detail resolution) or in blocks of 4 lines (inFine resolution). The first line of each block is MH coded, then the remaining lines in the block areMR coded using the first line as the reference line.

SMR—This is similar to MR coding except that data is treated in blocks of 8 lines (in Standard orDetail resolution) or in blocks of 16 lines (in Fine resolution).



MMR—Data is treated by the page (or the ECM block if the page needs more than one block). Thefirst line of the page is MH coded, then all the following lines on the page are MR coded using thefirst line as the reference line. In some models, MMR is only done for storing data into memory, or ifECM is being used.

EFC—The sending machine only includes fill bits in the data stream when the FIFO memory in thereceiver is full (normally fill bits are always added to the end of any line that is sent out in less thanthe time specified by the I/O rate).

New EFC—Fill bits are never added to the data, and the receiver uses the SAF memory or hard diskinstead of the FIFO memory. If the receiver's memory is full, it sends PIN and the line isdisconnected.

If ECM (the extension to Group 3 protocol known as Error Correction Mode) is used, EFC and NewEFC are not used.

The compressed data goes out to the modem on the data bus.

Compression is described in more detail in the section on compression.



Data Transfer to the Modem

I/O rate: The I/O (input/output) rate is the amount of time needed for the scanner or printer toprocess one scan line of image data (modulation and demodulation are not included in this time). Onthe transmitting side, it indicates the time needed to scan, process, and compress a scan line. Onthe receiving side, it indicates the time needed to reconstruct, process, and print a scan line. InGroup 3 transmission without ECM, I/O rates of the communicating machines must be the same. IfECM is used, I/O rate is not used (0 ms/line is assumed).

Without ECM


The FIFO has some unique functions, in addition to synchronizing data transfer from the CPU to themodem, as explained below.

Without EFC (Estimated Fillbit Control): During the protocol exchange, I/O rate capabilities arecompared. The I/O rates of both terminals must be the same during communication. The maximumI/O rate of the slower machine is used. Say that the chosen I/O rate is 10 ms/line. If the sendingmachine takes less than 10 ms to scan, process, and compress a particular scan line, it adds fill bits(zeros) to the end of the compressed scan line to make up the extra time. This keeps the twomachines synchronized.



With EFC: If EFC is used, the two terminals' FIFO sizes are compared during the protocol exchange,as well as the I/O rates. During transmission, the sending machine continually estimates how muchspace remains in the receiver's FIFO (the I/O rate, receiver's FIFO size, and amount of data sent areused in this estimation). Fill bits are not added to the end of each scan line, unless the receiver'sFIFO seems to be getting full; the transmitter then sends fill bits (zeros) until there is some space inthe FIFO. This system speeds up data transfer between the terminals.

With ECM

All compressed image data for an ECM block (normally one page, unless halftone is used) are heldin the ECM memory, and assembled into protocol frames before transmission.

At the receiving end, printing does not start until the whole block of data has been received.Therefore, there is no need to synchronize the scan line I/O rate of the two machines.

The FIFO is not needed for ECM; the ECM memory at each end acts as a buffer memory.

Printing is not done until a block of data has been assembled in the receiver's ECM memory.Therefore, there is no real time synchronization of the scan line I/O rate of the two machines.Because of this, no fill bits need to be exchanged between the terminals. This means that EFC is notused with ECM.

Note: In laser printers, the I/O rate is also 0 ms/line during reception. This is because the data isassembled in a page memory before printing.

ECM is described in more detail in the section on fax protocol, and EFC is described in more detail inthe section on compression.



Modulation

The data passes to the modem on the data bus as 8-bit parallel data. The modem converts this toserial and modulates it before passing it on to the network interface circuits.

Modulation techniques are described in detail in another section.

Attenuation

The signal is then attenuated and passed to the line.

Permissive Attenuation

For G3 and V.21 protocol signals, the attenuator ensures that the signal level output to the linematches the value programmed in the bit switches for tx signal level.

If the number is dialed as a Speed or Quick Dial, any value stored for tx level in the dedicatedtransmission parameters for this address will be used instead of the bit switch value.

Note: For G2, G1, and PIS (462 Hz) signals (these are all now obsolete), the output to the line isslightly different than for G3. For example, if the bit switches specify -9 dBm, the differenttypes of signal will have the following level on entering the network.

G3, V.21: -9 dBG2, PIS (462 Hz): -8 dBG1: -12 dB.

The above values differ from model to model.



Programmable Attenuation

Programmable attenuation is only done in older models, some of which may still be in the field.

If programmable attenuation is required (which is not very often), a technician from the telephonecompany will visit the location and measure the output level from the machine. The technician willthen connect a programmable resistor to the rear of the machine; the resistor value is selectedcarefully to ensure that the machine's output level is between 0 and -15 dBm.

Programmable attenuation must then be switched on by a bit switch adjustment.

The bit switches and dedicated transmission parameters for signal level are ignored. The attenuationbetween points [A] and [B] on the circuit diagram is fixed (see the beginning of this section). Forexample:

G3, V.21: -5 dBG2, PIS (462 Hz): -4 dBG1: -8 dB

The above values differ from model to model.

G1 and G2 are now obsolete.



Exit to the Network

The signal then passes through an amplifier, which raises the signal level to make up for the signalloss as the data passes out to the line through the network interface circuits. The data then passes tothe line through the Di and Oh Relays, which do not change position during data transmission.

Notes1. The transmission level can be changed by bit switch, if local line conditions make it necessary.2. Dedicated transmission parameters are three bytes of settings, that can be programmed for each

Quick Dial Key and Speed Dial Code. The settings include transmission level, and initial modemrate. The settings can be programmed to suit the line conditions normally encountered whensending to the terminal stored in the Quick Dial Key or Speed Dial Code.

3. In older models programmable or permissive attenuation can be selected by a bit switchadjustment.

4. ECM is normally on. In some models, it can be switched off for a particular destination usingdedicated tx parameters, or for all destinations by bit switch adjustment.

5. If transmitted signals are degraded (especially at higher frequencies) because of the length of wirebetween the modem and the local exchange, try adjusting the cable equalizer by bit switch. Thereare normally four values available, including zero (off). If the cable equalizer is switched on, highfrequencies are made louder and low frequencies are made softer. The cable equalizercharacteristic may vary depending on the modem in use. Modems used in fax machines generallyraise the levels of frequencies between 1700 Hz and 3000 Hz, and reduce the levels offrequencies between 300 Hz and 1700 Hz. If the cable equalization is overcorrected, outputsignals will be degraded again, leading to unnecessary modem rate fallback during training.



Return to StandbyAfter transmission, the next step dependson the status of the handset hook switch.

If the handset is on hook at the end of thecommunication, the cpu turns off the Diswitch to disconnect the fax machine fromthe dc loop, then the Oh relay inaccordance with the following diagram onthe right.

If the handset is off hook (for example, if theVoice Request feature was being used), theOh relay switches off before the Di switch,as shown on the right.

Note: The difference in timing is to meetPTT requirements in some Europeancountries.

OHRelay

DiSwitch

10 ms

Stbyu1.wmf

OHRelay

DiSwitch

5 ms

Stbyu2.wmf



Finally, the cpu turns off the power supply for all components except those needed for monitoring themachine and telephone line in standby mode. The machine is now back in standby mode.

Note

The machine must wait for a minimum amount of time before dialing the next number. This interval isnormally stored in RAM and can be adjusted. However, there may be a government requirementregarding the value, as for most of the adjustable communication parameters that are discussed inthis manual.



Others

Manual Dialing

An outline of the steps taken follows.

Document Detection: The user places the document in the feeder, and the tx motor feeds thedocument to the scan line.

Document Feed, Video Processing: These steps are the same as for automatic dialing.

DC Loop Closure, Dialing, and Signal Detection: The user picks up the handset. The handsethook switch closes the circuit between the machine and the telephone exchange (known as the dcloop). The user listens for dial tone then dials. The user presses Start after hearing a signal from theother end. There is no automatic call collision prevention after the user presses Start.

Data Transmission, Return to Standby: These steps are the same as for automatic dialing



Circuits

Machines without Auto Select Mode Machines with Auto Select Mode

TIP

RING

RI

TI

Network

CPU

+24VS

LINECURRENT

LINECURRENT

[A]

[B]

HandsetHookSwitch

LINECURRENT

TIP

RING

Network

LINECURRENT[A]

[B]

HandsetHookSwitch

RI

TI

+24VS

[C]

CPUAutoModeRelay

OhRelay

RingingSignal

Detector

Mandlu2.wmf



Picking up the Handset

After placing the document in the feeder, the user picks up the handset. The hook switch in thehandset closes the dc loop between itself and the local exchange.

Auto or Manual Receive modes: The cpu detects dc loop closure when pin A or pin B goes low; thepin that goes low depends on the polarity of the circuit.

Auto Select mode: The cpu detects that the handset is off hook when the signal on pin C changesstate. When the cpu detects this, it switches over the Auto Mode and Oh relays. (The above diagramshows the relays in standby mode for Auto Select mode.)

The +24V signal used here must remain on during standby mode. This is because pin A is also usedfor detecting when the handset is picked up in Auto Select mode.



Dialing

When the cpu detects the dc loop, the operation panel LED prompts the user to dial.

Dialing from the handset: The dial switch or tone generator in the handset sends the dial signal outto the line. The user presses Start after hearing a signal from the other end.

Dialing from the ten-key pad: When the first number is input at the ten-key pad, the Oh relayswitches into the down position (see the previous diagram). After the dial pulses or tones have goneout to the network, the Oh relay switches over again to connect the handset to the line. The userpresses Start after hearing a signal from the other end.

The cpu then connects the line to the fax machine by turning on the Di switch then switching over theOh relay 10 ms later. This is the opposite of the dc loop closure procedure for automatic dialing.

The reason for the above is as follows. If the Oh relay is closed first, the dc loop already establishedbetween the handset and the local exchange would be disconnected and the call would beterminated. So, the Di switch is closed first. There are now two dc loops; one to the handset, and onethrough the fax circuit. Then the Oh relay disconnects the handset to leave the fax machineconnected to the local exchange. In automatic dialing, there is no dc loop formed with the localexchange at this time, so the Oh relay can be switched over first without disconnecting the call.

Document feed, video processing, data transmission, and return to standby then proceed aspreviously described.

The user may pick up the handset during communication (for a voice request), or before a documentis placed in the feeder (for example, to make a phone call).



When the user picks up the handset, the hook switch inside the handset closes.

If this is done in standby mode, the dc loop then forms through the hook switch in the handset. Thecpu detects line current, which informs it that the handset has been picked up.

If the user picks up the handset after the dc loop has been closed (for example, to answer a voicerequest), the cpu cannot directly detect that the handset has been picked up. The user has to pressthe Stop key after picking up the handset. Then the Oh relay switches over to connect the handset tothe local exchange.



Immediate Transmission

An outline of the procedure follows.

Document Detection: The user places the document in the feeder, and the CPU turns on thescanner lamp when it detects the document.

Call Collision Prevention, DC Loop Closure, Line Monitoring, Dialing, and Signal Detection:After the user has pressed Start on the operation panel, the machine feeds the first page partwayinto the scanner. The machine then dials the other party, before scanning the document.

Document Feed: When the other terminal has been reached and handshaking and modem traininghave been done, the machine scans the document. When document stamping is switched on, thepage is stamped if transmission was successful.

Video Processing: While the machine scans the document, it converts the scanned data fromanalog to digital, and passes it through the video processing circuits.

Data Transmission: The data passes to the telephone line through the modem and networkinterface circuits.

Return to Stand-by: After all data has been transmitted, the page is fed out. The machine returns tostand-by.



Redialing

If there is a line failure, or if the line is busy, the machine can redial the same number automatically,as defined by parameters stored in RAM. (Also, the user can redial immediately by pushing theRedial key.)

There are RAM addresses to control the following:

• Redialing (memory transmission)

• Redialing (immediate transmission)



International Dialing

Some national PTTs require automatic detection of international dial and country dial tones.

International numbers are dialed as follows.

International dial tones and country dial tones are detected in the same way as PSTN dial tones,except that the timers and frequency limits are different.

0 P 009 112 P 123...

Tel. number

Pause

Country code

International dial access code

Pause

PSTNaccess code

If behindPABX

PABXMonitoring

PSTNMonitoring

International DialToneDetection

Country DialToneDetection

DCLoopClosure



Note: The necessary parameters are held in RAM.

International Dial ToneAcceptable frequency range Detection timeReset time Continuous tone timePermissible drop time Wait interval

Country Dial ToneAcceptable frequency range Detection timeReset time Continuous tone timePermissible drop time Wait interval

OtherInternational dial access code



Auto Dialing from behind a PABX

Outline

The procedure is as follows.

Document Detection, Document Feed, Video Data Processing, Call Collision Prevention, DCLoop Closure: These are the same as for transmission without PABX. When the machine goes intotransmit mode, it checks for incoming calls, then it connects to the PABX by switching over the Diswitch and Oh relay.

Line Monitoring: Some local conditions require the machine to monitor the line for PABX linecurrent, dial tones, busy tone, and ringback tone. If line monitoring is disabled, the machine waits forthe PABX wait interval before going on to the next step (in the USA, this interval is 2 s).

Access to the PSTN: The machine must gain access to the PSTN through the PABX by dialing anaccess code.

Line Monitoring, Telephone Number Dialing, Signal Detection, Data Transmission, Return toStandby: These are the same as for transmission without PABX.

Line monitoring and access to the PSTN are explained in more detail on the following pages.



Line Monitoring

1. Line Current

This is the same as for PSTN line current detection.

2. Dial Tone

The machine monitors the line for PABX dial tone in the same way as when it monitors the line forPSTN dial tone. However, the following parameters for dial tone detection are different and arestored in separate RAM addresses.

• Acceptable frequency range• Detection time• Reset time• Continuous tone time• Permissible drop time

If PABX line monitoring is enabled and parameters are already programmed, you can disable dialtone detection. The method differs from model to model.

If PABX dial tone detection is disabled, the machine will wait for the PABX wait interval (see the nextpage) before dialing the PSTN access code. This interval is stored in RAM.



3. Busy Tone Detection

This is the same as for basic transmission, except that the following parameter has a separate RAMaddress.

• Acceptable frequency range

4. Ringback Tone Detection


• Detection time



Access to the PSTN

The machine sends out the first digit ofthe phone number, which should be thePSTN access code. The PSTN accesscode is programmed by bit switch.

If this first digit is the same as the valuespecified by the bit switch, the cpurecognizes the access code and starts tomonitor the line from the PABX.

Note that the PSTN access code can be atwo-digit code. In this case, the cpumonitors the line for line current and dialtone after the user dials the two-digit codespecified by the access code bit switch.

If line monitoring is disabled, the cpu waits for preset intervals before dialing. The intervals are:

• [A]: PABX wait interval

• [B]: PSTN wait interval; this is the same as the interval discussed in DC Loop Closure.

Both intervals are stored in RAM and can be adjusted. The above diagram shows the set-up for theUSA; A is 2 s and B is 4 s.

2s 4s

0 5 5 5

LoopClosure

ExampleAccessCode: 0Tel.No.: 555

[A] [B]

Pabxe1.wmf



The next step depends on the PSTN access mode selected. There are three types: loop start,ground start, and flash start.

1. Loop Start

After the cpu recognizes the PSTN accesscode, it monitors the line for line current anddial tone, then starts to dial the destinationtelephone number.

2. Ground Start

After the cpu recognizes the PSTN access code, itgains access to the line by closing the Gs relay for acertain interval [A], which is stored in RAM.

PABXLine CurrentandTone Detection

0 1 2 3

DCLoopClosure

PSTNLineCurrent and

Tone Detection

Pabxe2.wmf

DCLoopClosure

PSTNLineCurrent and

ToneDetectionBegins

[A]

Gs Relay

Pabxe3.wmf



3. Flash Start

After the cpu recognizes the PSTN access code,it gains access to the PSTN by opening the Direlay for a certain interval [A], which is stored inRAM.

Circuit DCLoopClosure

PSTNLineCurrent and

ToneDetectionBegins

[A]

Di Relay

Pabxu3.wmf

Gs

Ds

Di

OH

OH

Di

Ds

Gs

Driver

GS

Line

CPU

Handset

Pabxu5.wmf



4. Pauses

If the user enters one or more pausesafter the access code, the machinemonitors the PSTN then waits for thePABX pause time (stored in RAM) foreach pause dialed. Then it dials thenumber.

However, the machine will wait for onlyone pause:

• If the pause key was pushed morethan 8 times consecutively

• If the pause time RAM addresscontains FF.

Notes

The access method can be selected by bit switch. The following settings are available; no PABX,loop start, ground start, and flash start.

The PSTN access code can be programmed by bit switch.

The PABX pause time ([A] in the above diagram) can be changed by a RAM address adjustment.

DCLoopClosure

PSTNLineCurrent and

Tone Detection

PABXLineCurrent and

ToneDetection

Example: 0PPP123

0 1 2 3

[A] [A] [A]

Pabxe6.wmf



EUROPEAN/ASIAN MODELS

Call Collision Prevention

Overview

After placing a document in the feeder, the user enters the telephone number at the operationpanel's ten-key pad, then presses the Start key. The machine then scans the document and stores itin the SAF memory. The machine then prepares to dial.

Note: Remember that for transmissions that do not use the memory, the order of events is different.After the user presses Start, the document is fed partway into the scanner and the machinedials. Scanning and storing is done after the other end has been reached. See ImmediateTransmission for details.

However, before the machine dials, it must check whether another call is in progress or not, toprevent a collision of incoming and outgoing signals. If the machine detects that a call is already inprogress, it will wait until the line is clear before dialing.

There are two criteria for detecting whether a call is in progress.

1. Has a ringing signal been detected, or is a potential ringing signal still being analysed?

2. Is the local loop with the local telephone exchange closed?

To understand this, we need to understand how a fax machine connects to a PSTN (Public SwitchedTelephone Network). This explanation begins on the next page.



PSTN Circuit

DC Loop Overview

Every telephone or fax machine is connectedto a local exchange of the PSTN through atwo-wire pair. One wire is called "Tip" and theother is called "Ring"; these names refer tothe tip and ring parts of the plugs used inmanual switchboards (in Europe, L1 and L2are often preferred). This two-wire circuit isknown as the "dc loop", or "local loop".

Each telephone and fax machine contains aswitch which opens and closes the local loop.When the switch is closed, dc generated bythe local exchange flows through the dc loop.The voltage on the dc loop varies from area toarea; for example, in the USA, it is about 48 V.

LOOPOPEN

LOOPCLOSED

Fax or Telephone

+

Fax or Telephone

+

Local Exchange

Local Exchange

Dcloopu1.wmf



DC Loop through Telephone

When the telephone is on-hook, the hook switchconnecting it to the local exchange is open, and dcfrom the local exchange cannot pass through thedc loop. However, the telephone's ringer isconnected (the ringer does not allow the dc fromthe exchange to pass, but allows the ac ringingsignal to pass).

When the handset is picked up, pressure on thehook switch is released, and the switch closes.Then, dc from the local exchange passes throughthe dc loop.

DialingCircuit

HookSwitch

Ringer

TELEPHONE(Simplified)

TIP

RING

+

RingingSignal

Generator(20-47 Hz)

LOCALEXCHANGE

Dcloopu2.wmf



DC Loop through Fax Machine with External Telephone

Inside the fax machine, two components (called theOh relay and the Ds relay) act as the fax machine'shook switch.

When the machine is in standby mode (as shownabove), the Oh relay is set up so that the network isconnected to the external telephone (commonlyknown as the handset); in this set-up, the handsetcan be used as a normal telephone, as explainedon the previous page. The dc loop is open, becausethe handset's hook switch is open. However, theringing signal detector in the fax machine and theringer in the handset are both connected to the line.

When the machine closes the dc loop, it switchesover the Oh relay to disconnect the handset fromthe line. Then it closes the Ds relay to connect thefax machine to the dc loop. The fax machine's cpuwill be able to detect dc by monitoring the linecurrent detector.

Note: In France, the Di switch is in series with theOh relay instead of the Ds relay, and the Direlay closes the dc loop.

RingingSignal

Generator(20-47 Hz) +

LOCAL EXCHANGE

+24V


RingingSignal

Detector

LineCurrentDetector

HandsetHook Switch

To/FromFax Circuits

Dcloopu3.wmf

Ds relay

Oh relay



Call Collision Prevention in Fax Machines

For 0.2 s after the user presses Start, the cpumonitors the ringing signal detector and the linecurrent detector to check that the local loop hasnot already been closed (if the local loop has beenclosed, there will be current on the telephone line).If a possible ringing signal is still being analyzedwhen the user presses Start, the cpu will wait for 8s, then check whether the signal is still beinganalyzed.

The call collision prevention circuit is shownbelow. The circuit shown is for a fax machine instandby mode.

Ringing signal detector: This circuit consists of some zener diodes and a photocoupler. It isadjustable, to allow for variations in ringing signals within Europe. If the voltage of an incoming signalis high enough, it turns on the photocoupler. Then, the cpu detects that its connection to the ringingsignal detector has been grounded.

Line current detector: This is a Hall effect sensor. The cpu detects line current when one of thesensor outputs is grounded; the output that is grounded depends on the polarity of the dc on theloop.

LineCurrentSensor

Network

Handset

RINGINGSIGNAL

LINECURRENT

LINECURRENT

L1

L2

T1

T2

CPU

Dcloope4.wmf



DC Loop Closure and Line MonitoringAfter it has been confirmed that there is no possibility of call collision, the machine automaticallycloses the circuit between itself and the local exchange; this circuit is commonly called the dc loop, orthe local loop. Closing the dc loop is the fax machine's way of going off-hook before dialing.

In some areas, dialing cannot begin until the machine has checked for dial tone and line current. Thisis known as "line monitoring".

DC Loop Closure

The fax machine closes the dc loop afterchecking for incoming calls. If there is noincoming call, the cpu closes the dc loop byactivating the Oh relay to disconnect thehandset from the line. Then, after 5 ms, itcloses the Ds relay to connect the faxmachine to the line.

The cpu then waits for the 'PSTN waitinterval' [A] of about 2 s before starting todial.

The PSTN wait interval can normally be adjusted by RAM address.

On the following circuit diagrams, curved arrows show the relays switching over from standby modeto close the dc loop.

OHRelay

Only if

5 ms

Ds or DiRelay

Diallingstarts

[A]

Dccle1.wmf



In most countries, the circuit is as shown in the left-hand diagram (the Ds relay closes the dc loop). InFrance, the circuit is as shown in the right-hand diagram (the Di relay closes the dc loop). The Gsrelay is not used for dc loop closure; it is only shown for reference in these diagrams.

Gs

Di Ds

OH

OH

Di

Ds

Gs

GS

Line

5

5

5

Driver CPUHandset

Dccle2.wmf

Gs

Ds

Di

OH

OH

Di

Ds

Gs

Driver

GS

Line

5

5

CPU

Handset

Dccle3.wmf



Line Monitoring

Before starting to dial, conditions in parts of Europe require that the machine monitors the linecurrent detector for line current, and signals on the line for dial tone.

Therefore, in Europe/Asia models, the PSTN wait interval can be replaced by dial tone and linecurrent detection, if required by local conditions. (Dial tone and line current detection are alsoavailable in USA versions of some of the more complex models.)

Line Current Monitoring

Line current detection allows the machine tocheck whether the dc loop has been closed. Ifthere is no line current, the dc loop may still beopen.

The machine uses the following parameters todetect line current.

• Line current wait time [A]• Line current detection time [B]• Line current drop detection time [C]

[A] starts when the dc loop closes. [B] starts when the line current first reaches the machine.

The machine checks for line current during [A]. Line current must be on the line for [B] or longerbefore it is recognized by the cpu. If the cpu has not recognized line current during the interval [A],

[B]

[A]

Line Current MonitoringStarts Here

[C]

Dcclus3.wmf



the machine disconnects. However, if the line current has started but has not been on for [B] when[A] expires, detection continues until it has been on for [B].

After starting [B], the machine continually checks the line current for interruptions. If any singleinterruption lasts for [C] or longer, the line is cut, [A] and [B] are reset, and the machine returns tostand-by.

Dial Tone Monitoring

The local exchange sends a dial tone to inform the user thatthe exchange can accept a telephone number. Dial tonemonitoring allows the fax machine to check for this tonebefore dialing; if there is no dial tone, the exchange may notbe ready to accept a telephone number.

The machine uses the following parameters to detect dialtone.

• Acceptable frequency range• Dial tone detection time [A]• Reset time [B]• Continuous tone time [C]• Permissible drop time [D]

[B] starts when the dc loop is closed. Dial tone must appearbefore [B] expires. If dial tone appears just as [B] expires, detection continues and the deadline atthe end of [B] is ignored.

Dial ToneDetected

Dial Tone<[C]

>=[D]

<[D]

[C]

Dial tonefirst appears

[A]

DCLoopClosure

[B]

Dcclus4.wmf


Group 3 Fax Communication

The machine detects a dial tone when the tone continues for [C][A] must have passed since the dial tone first appeared. Interrup

Switching Line Monitoring On/Off

A nation that requires line monitoring has the necessary parameare normally activated when the country code (normally a bit swination.

However, if required, line current and dial tone can be disabled; to model.

Similarly, in countries which normally have line monitoring disabldetection can be enabled; however, the parameters for detectionappropriate RAM addresses.

When line monitoring is disabled, the machine waits for thePSTN wait interval [A] before starting to dial.

9 August 2003

Transmission

or longer without interruption. Also,tions shorter than [D] are ignored.

ters programmed in the ROM; theytch setting) is set to the code for that

the way to do this varies from model

ed, line current and dial tone will have to be stored in the

Dial Pulses or Tones

[A]

LoopClosure

Dcclus5.wmf

Page 507


Note:

The following parameters can be programmed by RAM address.

Line Current MonitoringLine current wait time Line current detection timeLine current drop detection time Line current monitoring on/off

Dial Tone MonitoringAcceptable frequency range Dial tone detection timeReset time Continuous tone timePermissible drop time Dial tone monitoring on/off

OtherPSTN wait interval



Dialing

Overview

After the dc loop has been closed, the machine can dial. In automatic dialing mode, the machinedials in accordance with the number entered by the user at the operation panel, either in full, or as aQuick Dial or Speed Dial.

There are two types of dialing: pulse dialing, and tone dialing. The dialing method must match thedialing mode that can be accepted by the local exchange, or the machine will not be able to dial out.

The dialing method can be chosen by a user function in most countries.



Pulse Dialing

Pulse dialing was originally developed tooperate mechanical switching systems inthe local exchanges.

The machine sends voltage pulses to thelocal exchange by interrupting the dc loop.It does this by opening and closing the Diswitch. Each digit is represented as adifferent number of pulses. For example, todial a "2", the machine sends out 2 pulses.

The Oh Relay remains fixed during dialing(it does not move until the machine returnsto stand-by mode). The Di switch is a relay.This is because of PTT requirements insome areas. (PTTs are national telephonenetwork administrative bodies.)

When the Di relay is opened and closed, there are sharp voltage peaks at the leading and trailingedges of the dial pulses, which could damage circuits in the machine. Because of this, a extra relayis added to the dialing circuit; this relay is known as the Ds relay. The Ds relay is opened while the Direlay is dialing, to prevent voltage spikes from damaging the machine.

Di

Ds

OH

Di

DsDriver

Line

5 5

To themodemand other data

circuits

CPU

Handset

Diale1.wmf



Each digit of the telephone number is sent out as a pulse train. The cpu sends out the dial pulses byswitching the Di and Ds relays in accordance with the following timing.

Example: Dialing 32

The time that the Di relay opens is called thebreak time [A] and the time that it closes iscalled the make time [B]. Each pulse sentout on the line is made by opening andclosing the Di relay.

A minimum pause [C] is required betweeneach digit, regardless of whether the userpressed the pause key while dialing.

Ds[C]

[E]

3 2

[D] [A]

[B] [B] [B]

[A] [A] [A] [A]

Di

[D][E]

Diale2.wmf



Notes:

Most countries dial in the same way (the number of pulses sent out [P] is the same as the numberdialed [N]). However, some areas require different types of pulse dial signals. For example, in Oslo,P must be 10 - N, and in Sweden, P must be N + 1. The required mode can be selected by bit switchadjustment.

Pulse dialing can be done at two rates: 10 pulses per second (pps) or 20 pps. If the local exchangecan only handle 10 pps dialing, the machine must not be set to dial at 20 pps. The dial pulse rate canusually be adjusted by bit switch.

Parameters A to E illustrated on the diagrams in this section are programmable.

For pulse dialing at 10 pps, the times stored in the NCU parameters are used as explained in thissection. However, at 20 pps, only half the values in parameters A, B, D, and E are used, and three-quarters of the value in parameter C.



In France, the relay circuit and the relay timing are different, as already mentioned. The principle isthe same, however.

Ds

Di

OH

Di

DsDriver

Line

55

To the modemand other data

circuits

CPU

Handset

Diale3.wmf

Ds

[C]

[E]

3 2

[D] [A]

[B] [B] [B]

[A] [A] [A] [A]

Di

[E] [D]

Diale4.wmf



Tone Dialing

Overview

Each dialed digit is sent out as a DTMF (Dual Tone MultiFrequency) tone, which is a mixture of two frequencies. Thefollowing diagram shows what frequencies are generated foreach digit on a typical telephone keypad. For example, a '5' isrepresented by a 770 Hz tone combined with a 1,336 Hz tone.

The DTMF tone frequencies are the same throughout theworld. They were carefully chosen so as not to coincide withother frequencies that may occur on the line.

In some types of telephone equipment, the DTMF circuitremains on line after the call has been connected. This allowsthe use of DTMF tones for giving orders to the remote terminal(e.g., extracting information from a remote database).

The advantages of using DTMF over pulse dialing are asfollows.

• Dialing is faster

• DTMF tone generation circuits are compact solid-state circuits

• There can be end-to-end signalling after call connection, as mentioned in the previous paragraph

Diale5.wm



DTMF Tone Generation

The diagram shows how DTMF tones aregenerated in fax machines.

The cpu generates two square waves ofthe required frequencies. These each passthrough a low pass filter to remove noise,and are added together.

In the attenuator, the DTMF tone isattenuated. The attenuation value isdifferent from that used for the attenuationof facsimile data.

The DTMF tone is then amplified tocompensate for the signal loss betweenthe attenuator and the telephone line. Thetone then passes to the line through theDs or Di relay and the Oh relay, whichremain fixed during tone dialing.

9 August 2003

Transmission

To theNetwork

Filter

Filter

Adder Attenuator

CPU

Dialu3.wmf

Page 515


Attenuation of DTMF Tones

A variable resistor can be used to adjust the signal level within a range of about 2 dB.

Note: The DTMF tone attenuation value can be adjusted by RAM address. However, unlike theattenuation value for facsimile data, it cannot be adjusted using dedicated transmissionparameters or bit switches.

Timing

DTMF tones are sent out during the DTMF on time[A] as shown in the diagram.

Note: The DTMF tone on time [A] and off time [B]can be adjusted by RAM address.

Pauses

If the user dials a pause using the Pause key, the machine waits for a pre-programmed intervalbefore sending the next tone or pulse.

Note: The pause interval can be changed using a RAM address adjustment.

[A] [B]Diale7.wmf



Signal Detection

Overview

After dialing, the machine waits for the response from the other end. The response is usually either aCED tone, a busy tone, or a ringback tone. These tones are known as progress tones. Instead of aprogress tone, a protocol signal such as NSF or DIS may be detected at this time.

The received signal passes through two filters. A highpass filter (with a cut off of about 300 Hz) removes lowfrequencies, such as noise from the fax machine'spower supply, and a low pass filter (with a cut off ofabout 2100 Hz) removes high frequencies, such asnoise from overhead railway power cables.

The signal then passes to a programmable gainamplifier, which raises the signal level enough for themachine's hardware to analyze it. The minimum signallevel on the line will vary from country to country, sothe amplifier is programmable. For example, in typicalUSA models, the amplifier is set up so that signalsweaker than -53 dBm are not detected.

The amplified signal is converted to digital, then passed to the tone detector in the cpu.

FromtheNetwork

Filters

ProgrammableGain

Amplifier

A/DConverter

CPU

Sigdet.wmf



The incoming signal may determine whether or not the machine goes into transmit mode. Mostmachines have bit switch or other settings to determine when the machine goes into transmit mode.The choices are typically as follows:

• After dialing• After receiving NSF or DIS• After receiving CED

Note: The gain of the amplifier depends on the country code (the country code is selected by a bitswitch adjustment). However, the gain can be changed by a RAM address adjustment; in mostmachines, there are 4 possible values to choose from.



Busy Tone Detection

If the call has gone through and if the called terminal is already off hook (i.e., the other end is busy),the local exchange at the other end sends back a busy tone.

If the machine detects busy tone, it will disconnect the line. The number will be redialed (seeRedialing), unless the maximum number of redials have already been made.

If busy tone detection is disabled and the line is busy, the machine will hold the line until the ITU-TT1 timer (about 1 minute) runs out. So busy tone detection can reduce the amount of time themachine holds the line.


BUSYNetworkDIALLINGSIGNAL

BUSYTONE

LocalExchanger

LocalExchanger

Sigdet2.wmf



- Busy Tone with Cadence -

In many countries, the busy tone has acadence (a fixed on-off cycle), so themachine measures the on and off times ofthe received signal and compares them withvalues programmed in the RAM.

RAM addresses specify four permissiblelengths for each signal state. The machinefirst checks if the signal has a length withinrange 1. If it does not, then range 2 isselected, and so on. An example is shownbelow, in which the on-off time durationsare found to be within range 3.

Note

The following values are stored in RAM.

• Range 1, ON time Range 1, OFF time• Range 2, ON time Range 2, OFF time• Range 3, ON time Range 3, OFF time• Range 4, ON time Range 4, OFF time• The number of cycles required for detection (for example, a setting of 4 means that ON-OFF-ON

or OFF-ON-OFF must be detected twice).

Busy Tone

DetectionFlag

ON OFF ON OFF ON OFF

Out ofRange1

Out ofRange2

WithinRange3

(1) (2) (3) (4)

TwoCycles

WithinRange3

WithinRange3

WithinRange3

Sigdet3.wmf



• ON or OFF time tolerance (+/-), for ranges 1 to 4.• Acceptable signal frequency range

- Continuous Busy Tone -

In some countries, such as the UK, the busy signal is not a cadence. The busy tone must continuefor a certain time before the machine detects it.

Note: The minimum time required for continuous busy tone detection is stored in RAM.



Ringback Tone Detection

If the call has gone through and if the called terminal is on hook, the local exchange at the other endsends a ringing signal to the called party; at the same time it sends a ringback signal back to thecaller.

Ringback tone detection is always switched on in Austria. Ringback tone is detected if the ringbacktone is longer than the minimum ringback tone detection time (0.1 s), which is stored in RAM.



LocalExchanger

LocalExchanger

RINGBACKTONE

NOREPLYYET

Sigdet4.wmf



- If the machine at the other end is a telephone -

When the phone rings at the other end, the transmitting machine detects ringback tone. The otherparty picks up the handset when the phone rings, and replaces it when there is no voice on the line.Then, the local exchange at the receiving end sends back a busy tone to the transmitter (this isnormal in Austria).

When the transmitter detects this busy tone, it immediately disconnects the line without waiting forthe ITU-T T1 time to expire. Ringback tone and busy tone were both detected on this call; in suchcases, the software in the transmitter disables automatic redialing for this number.

Note: In Austria, it is necessary to prevent a fax machine from redialing addresses for which the T1timer expired on the first attempt.

- If the machine at the other end is a fax machine -

In Austria, the receiving fax machine will close the dc loop after it has detected one ringing signal.(So, the ringback tone to the transmitter will be short, but not too short for detection.)

Immediately after closing the dc loop, the receiving machine will send CED. If the user at thereceiving end presses Stop after this, both machines will disconnect immediately.

The transmitter will not receive busy tone from the other end, as it has already disconnected, so thenumber can be redialed automatically.



Note

The ringback tone has the same frequency as the busy tone.

The only RAM address that must be programmed for ringback tone detection is as follows.Ringback tone detection time

CED Detection

If the receiver is a fax terminal in Auto Receive (Fax) mode, it will emit a 2100 Hz tone called CED.

This signal informs the caller that they have connected to a fax machine. CED is the high-pitchedtone that prompts the user to press the Start key when using Manual Dialing.

In automatic dialing mode, the transmitting fax terminal confirms CED detection when the CED tonecontinues for 200 ms or more. Then it starts to scan the document.



LocalExchanger

LocalExchanger

CEDTONE

FAXMODE

CEDTONE

Sigdet5.wmf



Data TransmissionThe data transmission circuit is shown on theright. The cpu retrieves the data from theSAF memory, processes it, and passes it tothe modem. The modem modulates the datato convert it into a form that is suitable fortransmission over the public telephonenetwork. The data is then attenuated to thecorrect signal strength for transmission.

Details of the major steps follow.

Processing in the CPU

Outline

The cpu retrieves the data from the SAFmemory and reconstructs it (if it wascompressed before storage into the SAF).The cpu then processes the data beforesending it to the modem. The signal to themodem is eight-bit parallel, with one bitrepresenting one picture element (unless thedata was reduced—see Digital Processingfor details on reduction).

9 August 2003

Transmission

To theNetwork

SpeakerVolume and

On/OffControl

Modem

Attenuator

L1

L2

Attenuator

SAFMemory

VariableResistor

CPU

[B]

[A]

Tx-e.wmf

Page 525


Compression

Compression reduces the number of bits in the data signal, and therefore the transmission time forone page.

MH, MR, and MMR compression are done according to ITU-T standards.

A proprietary procedure called EFC (Estimated Fillbit Control) may be applied to the compresseddata. EFC is not strictly a compression technique, but it improves the efficiency of data transfer bycontrolling the number of fill bits inserted by the transmitter at the end of each line of data (seebelow).

The data is compressed in accordance with the method agreed in the protocol between thetransmitting and receiving machines. In the obsolete Group 2 and Group 1 modes, the data is notcompressed before transmission.

Brief explanations of the different coding types follow. MH and MR coding are explained in detail inthe ITU-T recommendations for Group 3 facsimile.

MHEvery line is MH coded.

MRData is treated in blocks of 2 lines (in Standard or Detail resolution) or in blocks of 4 lines (inFine resolution). The first line of each block is MH coded, then the remaining lines in the block areMR-coded using the first line as the reference line.

SMRThis is similar to MR coding except that data is treated in blocks of 8 lines (in Standard orDetail resolution) or in blocks of 16 lines (in Fine resolution).



MMR—Data is treated by the page (or the ECM block if the page needs more than one block). Thefirst line of the page is MH coded, then all the following lines on the page are MR coded using thefirst line as the reference line. In some models, MMR is only done for storing data into memory, or ifECM is being used.

EFC—The sending machine only includes fill bits in the data stream when the FIFO memory in thereceiver is full (normally fill bits are always added to the end of any line that is sent out in less thanthe time specified by the I/O rate).

New EFC—Fill bits are never added to the data, and the receiver uses the SAF memory or hard diskinstead of the FIFO memory. If the receiver's memory is full, it sends PIN and the line isdisconnected.

If ECM (the extension to Group 3 protocol known as Error Correction Mode) is used, EFC and NewEFC are not used.

The compressed data goes out to the modem on the data bus.

Compression is described in more detail in the section on compression.



Data Transfer to the Modem

I/O rate: The I/O rate is the amount of time needed for the scanner or printer to process one scanline of image data (modulation and demodulation are not included in this time). On the transmittingside, it indicates the time needed to scan, process, and compress a scan line. On the receiving side,it indicates the time needed to reconstruct, process, and print a scan line. In Group 3 transmissionwithout ECM, I/O rates of the communicating machines must be the same. If ECM is used, I/O rate isnot used (0 ms/line is assumed).

Without ECM


The FIFO has some unique functions, in addition to synchronizing data transfer from the CPU to themodem, as explained below.

Without EFC (Estimated Fillbit Control): During the protocol exchange, I/O rate capabilities arecompared. The I/O rates of both terminals must be the same during communication. The maximumI/O rate of the slower machine is used. Say that the chosen I/O rate is 10 ms/line. If the sendingmachine takes less than 10 ms to scan, process, and compress a particular scan line, it adds fill bits(zeros) to the end of the compressed scan line to make up the extra time. This keeps the twomachines synchronized.

With EFC: If EFC is used, the two terminals' FIFO sizes are compared during the protocol exchange,as well as the I/O rates. During transmission, the sending machine continually estimates how much



space remains in the receiver's FIFO (the I/O rate, receiver's FIFO size, and amount of data sent areused in this estimation). Fill bits are not added to the end of each scan line, unless the receiver'sFIFO seems to be getting full; the transmitter then sends fill bits (zeros) until there is some space inthe FIFO. This system speeds up data transfer between the terminals.

With ECM

All compressed image data for an ECM block (normally one page, unless halftone is used) are heldin the ECM memory, and assembled into protocol frames before transmission.

At the receiving end, printing does not start until the whole block of data has been received.Therefore, there is no need to synchronize the scan line I/O rate of the two machines.

The FIFO is not needed for ECM; the ECM memory at each end acts as a buffer memory.

Printing is not done until a block of data has been assembled in the receiver's ECM memory.Therefore, there is no real time synchronization of the scan line I/O rate of the two machines.Because of this, no fill bits need to be exchanged between the terminals. This means that EFC is notused with ECM.

Note: In laser printers, the I/O rate is also 0 ms/line during reception. This is because the data isassembled in a page memory before printing.

ECM is described in more detail in the section on fax protocol, and EFC is described in more detail inthe section on compression.



Modulation

The data passes to the modem on the data bus as 8-bit parallel data. The modem converts this toserial and modulates it before passing it on to the network interface circuits.

Modulation techniques are described in detail in another section.

Attenuation

The signal is then attenuated and passed to the line.

For G3 and V.21 protocol signals, the attenuator ensures that the signal level output to the linematches the value programmed in the bit switches for tx signal level.

If the number is dialed as a Speed or Quick Dial, any value stored for tx level in the dedicatedtransmission parameters for this address will be used instead of the bit switch value.

Note: For G2, G1, and PIS (462 Hz) signals, the output to the line is slightly different than for G3. Forexample, if the bit switches specify -9 dBm, the different types of signal will have the followinglevel on entering the network. The following values differ from model to model.

G3, V.21: -9 dBG2, PIS (462 Hz): -8 dBG1: -12 dB

There is also a variable resistor, which can be used to adjust the signal level within a small range,typically 2dB.



Exit to the Network

The signal then passes through an amplifier, which raises the signal level to make up for the signalloss as the data passes out to the line through the network interface circuits. The data then passes tothe line through the Di (or Ds) and OH relays, which do not change position during data transmission.

Notes

1. The transmission level can be changed by bit switch, if local line conditions make it necessary.

2. Dedicated transmission parameters are three bytes of settings, that can be programmed for eachQuick Dial Key and Speed Dial Code. The settings include transmission level, and initial modemrate. The settings can be programmed to suit the line conditions normally encountered whensending to the terminal stored in the Quick Dial Key or Speed Dial Code.

3. ECM is normally on. In some models, it can be switched off for a particular destination usingdedicated tx parameters, or for all destinations by bit switch adjustment.

4. If transmitted signals are degraded (especially at higher frequencies) because of the length ofwire between the modem and the local exchange, try adjusting the cable equalizer by bit switch.There are normally four values available, including zero (off).If the cable equalizer is switched on, high frequencies are made louder and low frequencies aremade softer. The cable equalizer characteristic may vary depending on the modem in use.Modems used in fax machines generally raise the levels of frequencies between 1700 Hz and3000 Hz, and reduce the levels of frequencies between 1700 Hz and 300 Hz.If the cable equalization is overcorrected, output signals will be degraded again, leading tounnecessary modem rate fallback during training.



Return to StandbyAfter transmission, the next step depends on th

If the handset is on hook at the end of thecommunication, the cpu turns off the Dsrelay to disconnect the fax machine from thedc loop, then the Oh relay in accordance withthe timing diagram on the right.

If the handset is off hook (for example, if theVoice Request feature was being used), theOh relay switches off before the Ds relay, asshown on the right.

Notes:

• The difference in timing is to meet PTTrequirements in some European countries.

• In France, the Di relay opens the dc loopinstead of the Ds relay.

D

9 August 2003

Transmission

e status of the handset hook switch.

OHRelay

10ms

s or DiRelay

Stbye1.wmf

OHRelay

5 ms

Ds or DiRelay

Stbye2.wmf

Page 532


Finally, the cpu turns off the power to all components except those needed for monitoring themachine and telephone line in standby mode. The machine is now back in standby mode.

Note: The machine must wait for a minimum amount of time before dialing the next number. Thisinterval is normally stored in RAM and can be adjusted. However, there may be a governmentrequirement regarding the value, as for most of the adjustable communication parameters thatare discussed in this manual.



Others

Manual Dialing

Outline

An outline of the steps taken follows.

Document Detection: The user places the document in the feeder, and the tx motor feeds thedocument to the scan line.

Document Feed, Video Processing: These steps are the same as for automatic dialing.

DC Loop Closure, Dialing, and Signal Detection: The user picks up the handset. The handsethook switch closes the circuit between the machine and the telephone exchange (known as the dcloop). The user listens for dial tone then dials. The user presses Start after hearing a signal from theother end. There is no automatic call collision prevention after the user presses Start.

Data Transmission, Return to Standby: These steps are the same as for automatic dialing.



Picking up the Handset

After placing the document in the feeder,the user picks up the handset. The hookswitch in the handset closes the dc loopbetween itself and the local exchange.The CPU detects dc loop closure whenpin [A] or pin [B] goes low; the pin thatgoes low depends on the polarity of thecircuit.

Dialing

When the CPU detects the dc loop, theoperation panel LED prompts the user todial.

• Dialing from the handset: The dialswitch or tone generator in thehandset sends the dial signal out tothe line. The user presses Start afterhearing a signal from the other end.

• Dialing from the ten-key pad: When the first number is input at the ten-key pad, the Oh Relayswitches into the up position (see the previous diagram). After the dial pulses or tones have gone

LineCurrentSensor

Network

CPU

LINECURRENT

LINECURRENT

Handset HookSwitch

[A]

[B]

Mandiale.wmf

Oh Relay



out to the network, the Oh relay switches over again to connect the handset to the line. The userpresses Start after hearing a signal from the other end.

The cpu then connects the line to the fax machine by turning on the Ds relay (or Di relay in France)then switching over the Oh relay 10 ms later. This is the opposite of the dc loop closure procedure forautomatic dialing.

The reason for the above is as follows. If the Oh relay is closed first, the dc loop already establishedbetween the handset and the local exchange would be disconnected and the call would beterminated. So, the Ds relay is closed first. There are now two dc loops; one to the handset, and onethrough the fax circuit. Then the Oh relay disconnects the handset to leave the fax machineconnected to the local exchange. In automatic dialing, there is no dc loop formed with the localexchange at this time, so the Oh relay can be switched over first without disconnecting the call. Seethe DC Loop Closure and Dialing sections for details of the automatic dialing circuit.

Document feed, video processing, data transmission, and return to standby then proceed aspreviously described.

The user may pick up the handset during communication (for a voice request), or before a documentis placed in the feeder (for example, to make a phone call).

When the user picks up the handset, the hook switch inside the handset closes.

If this is done in standby mode, the dc loop then forms through the hook switch in the handset. Thecpu detects line current, which informs it that the handset has been picked up.

If the user picks up the handset after the dc loop has been closed (for example, to answer a voicerequest), the cpu cannot directly detect that the handset has been picked up. The user has to press



the Stop key after picking up the handset. Then the Oh relay switches over to connect the handset tothe local exchange.

Immediate Transmission

An outline of the procedure follows.

Document Detection: The user places the document in the feeder, and the cpu turns on thefluorescent lamp when it detects the document.

Call Collision Prevention, DC Loop Closure, Line Monitoring, Dialing, and Signal Detection:After the user has pressed Start on the operation panel, the machine feeds the first page partwayinto the scanner. The machine then dials the other party, before scanning the document.

Document Feed: When the other terminal has been reached and handshaking and modem traininghave been done, the machine scans the document. The page is stamped if transmission wassuccessful.

Video Processing: While the machine scans the document, it converts the scanned data to digital,and passes it through the video processing circuits.

Data Transmission: The data passes to the telephone line through the modem and networkinterface circuits.

Return to Standby: After all data has been transmitted, the page is fed out. The machine returns tostandby.



Redialing

If there is a line failure, or if the line is busy, the machine can redial the same number automatically,as defined by parameters stored in RAM. (Also, the user can redial immediately by pushing theRedial key.)

There are RAM addresses to control the following:

• Redialing (memory transmission)

• Redialing (immediate transmission)



International Dialing

Some national PTTs require automatic detection of international dial and country dial tones.

International numbers are dialed as follows.

International dial tones and country dial tones are detected in the same way as PSTN dial tones,except that the timers and frequency limits are different.

0 P 009 112 P 123...

Tel. number

Pause

Country code

International dial access code

Pause

PSTNaccess code

If behindPABX

Intdle1.wmf

PABXMonitoring

PSTNMonitoring

International DialToneDetection

Country DialToneDetection

DCLoopClosure

Intdle2.wmf



Note:

The necessary parameters are held in RAM.

International Dial ToneAcceptable frequency range Detection timeReset time Continuous tone timePermissible drop time Wait interval

Country Dial ToneAcceptable frequency range Detection timeReset time Continuous tone timePermissible drop time Wait interval

OtherInternational dial access code



Auto Dialing from behind a PABX

Outline

The procedure is as follows.

Document Detection, Document Feed, Video Data Processing, Call Collision Prevention, DCLoop Closure: These are the same as for transmission without a PABX. When the machine goesinto transmit mode, it checks for incoming calls, then it connects to the PABX by switching over theDs relay (or Di relay in France) and the Oh relay.

Line Monitoring: Some local conditions require the machine to monitor the line for PABX linecurrent, dial tones, busy tone, and ringback tone. If line monitoring is disabled, the machine waits forthe PABX wait interval before going on to the next step (in the USA, this interval is 2 s).

Access to the PSTN: The machine must gain access to the PSTN through the PABX (by dialing anaccess code for example).

Line Monitoring, Telephone Number, Dialing, Signal Detection, Data Transmission, Return toStandby: These are the same as for transmission without a PABX.

Line monitoring and access to the PSTN are explained in more detail on the following pages.



Line Monitoring

1. Line Current

This is the same as for PSTN line current detection.

2. Dial Tone

The machine monitors the line for PABX dial tone in the same way as when it monitors the line forPSTN dial tone. However, the following parameters for dial tone detection are different and arestored in separate RAM addresses.

• Acceptable frequency range• Detection time• Reset time• Continuous tone time• Permissible drop time

If PABX line monitoring is enabled and parameters are already programmed, you can disable dialtone detection. The method differs from model to model.

If PABX dial tone detection is disabled, the machine will wait for the PABX wait interval (see the nextpage) before dialing the PSTN access code. This interval is stored in RAM.



3. Busy Tone Detection


• Acceptable frequency range

4. Ringback Tone Detection


• Detection time



Access to the PSTN

The machine sends out the first digit ofthe phone number, which should be thePSTN access code. The PSTN accesscode is programmed by bit switch.

If this first digit is the same as the valuespecified by the bit switch, the cpurecognizes the access code and starts tomonitor the line from the PABX.

Note that the PSTN access code can be atwo-digit code. In this case, the cpumonitors the line for line current and dialtone after the user dials the two-digit codespecified by the access code bit switch.

If line monitoring is disabled, the cpu waits for preset intervals before dialing. The intervals are:

• [A]: PABX wait interval

• [B]: PSTN wait interval; this is the same as the interval discussed in DC Loop Closure.

Both intervals are stored in RAM and can be adjusted. The above diagram shows the set-up for theUSA; A is 2 s and B is 4 s.

2s 4s

0 5 5 5

LoopClosure

ExampleAccessCode: 0Tel.No.: 555

[A] [B]

Pabxe1.wmf



The next step depends on the PSTN access mode selected. There are three types: loop start,ground start, and flash start.

1. Loop Start

After the cpu recognizes the PSTN accesscode, it monitors the line for line current anddial tone, then starts to dial the destinationtelephone number.

2. Ground Start

After the cpu recognizes the PSTN access code, itgains access to the line by closing the Gs relay for acertain interval [A], which is stored in RAM.

PABXLine CurrentandTone Detection

0 1 2 3

DCLoopClosure

PSTNLineCurrent and

Tone Detection

Pabxe2.wmf

DCLoopClosure

PSTNLineCurrent and

ToneDetectionBegins

[A]

Gs Relay

Pabxe3.wmf


Group 3 Fa

3. Flash S

After the cit gains acrelay for aRAM. (In relay is us

Circuit

L

9 August 20

x Communication Transmission

tart

pu recognizes the PSTN access code,cess to the PSTN by opening the Ds certain interval [A], which is stored inFrance, the circuit is different; the Died. See DC Loop Closure.) DCLoop

ClosurePSTNLineCurrent and

ToneDetectionBegins

[A]

Ds Relay

Pabxe4.wmf

Di

Gs

OH

OH

Di

Ds

Gs

Driver

GS

ine

Ds

CPU

Handset

Pabxe5.wmf

03 Page 546


4. Pauses

If the user enters one or more pausesafter the access code, the machinemonitors the PSTN then waits for thePABX pause time (stored in RAM) foreach pause dialed. Then it dials thenumber.

However, the machine will wait for onlyone pause:

• If the pause key was pushed morethan 8 times consecutively

• If the pause time RAM addresscontains FF.

Notes

The access method can be selected by bit switch. The following settings are available; no PABX,loop start, ground start, and flash start.

The PSTN access code can be programmed by bit switch.

The PABX pause time ([A] in the above diagram) can be changed by a RAM address adjustment.

DCLoopClosure

PSTNLineCurrent and

Tone Detection

PABXLineCurrent and

ToneDetection

Example: 0PPP123

0 1 2 3

[A] [A] [A]

Pabxe6.wmf


Group 3 Fax Communication Reception

Reception

Overview

This section explains how a fax machine receives a fax message. The base of the description will befor Auto Receive (Fax) Mode. Points concerning Manual Receive (Tel) Mode and Auto Select (Auto)Mode are discussed in the relevant sections. In addition, a section at the end explains additionalfeatures.

Below follows a brief summary of the individual steps for Auto Receive Mode. These steps arebasically the same for most machines.

Ringing Signal Detection—When someone sends the unit a fax, the local exchange sends aringing signal to the unit. The CPU monitors the ringing signal detector. If Manual Receive Mode hasbeen selected, ringing signal detection is disabled.

Loop Closure—When the CPU confirms that the incoming signal is a ringing signal, it closes the dcloop with the local exchange. If the caller is not a fax machine, the unit will send out the pre-programmed voice message, if it has been enabled (some models do not have this feature). Thissection also explains how the machine treats an incoming call if the machine is in Manual ReceiveMode or Auto Select Mode.

Data Reception—Data from the line passes to the modem and to the CPU.

Printing – The machine prints the fax message and feeds it out. This process is not described in thissection.



Return to Standby—After the final page has come in, the unit disconnects the line. After printinghas finished, the unit disconnects the dc loop (in exactly the same way as for the end oftransmission). Note that if the message is received to memory first, printing takes place after thewhole message has been received and the machine has disconnected itself from the telephone line.This is explained in the Transmission section.

The circuits for European and Asian models are different from those for North American models.Because of this, two separate sections have been prepared.



North American Models

Ringing Signal Detection

Monitoring the Line

The ringing signal detector is a circuitcontaining a photocoupler and some zenerdiodes. The cpu constantly monitors theoutput [A] for a ringing signal unless theprinter is in use or the dc loop is alreadyclosed.

An incoming signal switches thephotocoupler on/off if the voltage is higherthan a certain voltage. The cpu analyzesthe signal [A].

The above circuit is for machines that donot have Auto Select Mode. The circuit formachines that have Auto Select Mode isdiscussed on the next page.

TIP

RING

RI

TI

Network

+24VS

[A]RingingSignal

Detector

Handset CPU

Rngdetu1.wmf



Auto Select Mode

Machines that have this extra reception modehave an extra relay in the network interface,called the Auto Mode relay. The circuit isshown below.

When the machine is standing by in AutoReceive mode, the relays are as shown above.

When the machine is standing by in ManualReceive mode, the Oh relay is in the upposition and the Auto Mode relay is in thedown position.

When the machine is standing by in AutoSelect mode, the Oh relay is in the downposition and the Auto Mode relay is in the upposition.

TIP

RING

RI

TI

Network

CPU

+24VS

OHRelay

AutoModeRelay

Handset

RingingSignal

Detector

Rngdetu2.wmf



Silent Ringing Detection

If Auto Select mode is used, the Oh relay is in the down position, so the handset cannot ring. Thismeans that the machine makes no noise when a call comes in, unless the incoming call is from atelephone; if CNG is not detected, the cpu rings the fax machine's internal buzzer.

If Auto Receive mode is used, the user may have the option to enable silent ringing detection. In thiscase, the Oh relay will be in the down position, disconnecting the handset ringer from the line.



Signal Analysis

A ringing signal must satisfy three basic criteria: frequency, number of rings, and continuity. In allmodels, the principles of ringing signal detection are the same. A few models differ slightly from theexplanation given below.

Frequency

When the cpu detects a signal, it measuresthe frequency. If the frequency is within thelimits specified by the parameters [A]programmed in the memory, the cpudetermines that it is a possible ringing signal.

Number of Rings

Ringing signals have a cadence, consistingof rings and intervals between rings, asshown on the previous page. The cpu countsthe rings.

However, the cpu does not increment the ring counter unless the ring was long enough. The first ringmust be longer than the interval [B], and subsequent ones must be longer than the interval [C].

A certain number of rings [D] must be detected before the cpu confirms that the incoming signal is aringing signal. When the count reaches the required value, the cpu confirms that the signal is a

One Ring

RingingSignal

[B] [C]

Ringing Signal,One Wavelength

[A]

[E]

Rngdete2.wmf



ringing signal. The machine then goes into receive mode, and the cpu turns on the power supply forall components.

Continuity

The ringing signal must also satisfy a continuity test. The time between the end of a ring and the startof the next ring must not exceed the interval [E]. Otherwise, ringing detection flags will be reset andthe next ring detected will be treated as the start of a new ringing signal.

Note: Parameters A to E described in this section can be adjusted.



DC Loop Closure

Auto Receive (FAX) Mode

After confirming the ringing signal, the cpu closes the dc loop by switching over the Oh relay thenturning on the Di switch. The timing is the same as for transmission. The machine sends CED to thetransmitting machine, to inform it that it has connected to a fax terminal.

Manual Receive (TEL) Mode

In manual receive mode, automatic ringing signal detection and loop closure are not done. The userpicks up the handset after hearing it ring; this closes the dc loop. The user then presses Start afterhearing the fax signal from the other end. Then the fax machine connects to the line by closing the Diswitch then switching over the Oh relay. The timing is exactly the same as for manual dialing.



Auto Select (AUTO) Mode

The machine detects the ringing signal in the same way as for Auto Receive Mode. However, the Ohrelay is in the down position in standby mode, so the handset does not ring.

If the machine detects CNG (which means that the other end is an auto-dialing fax machine), itcloses the dc loop and sends out CED. From this point, the machine behaves in the same way as if itwas in Auto Receive Mode.

If the machine does not detect CNG after 2 s, it will send out a voice message (if the machine hasthis function). Then, if CNG has still not come in within a certain time (let us call it [A]), the machinewill emit an alarm to alert the user. From this point, the machine must detect CNG or the user mustpick up the handset within a certain time (let us call it [B]). If the other party hangs up during thisinterval, the machine will also hang up.If the interval [B] expires, the machine sends out CED. If theother party is a fax machine in manual dialing mode, the other party will press Start, and faxcommunication can go ahead in the same way as for Manual Receive Mode. If the other party hangsup instead, this machine will also hang up.

Note: Timers A and B can be adjusted.



Data ReceptionThis section explains the path of data from thetelephone line to the cpu (non-memory transmission)or the SAF memory (memory transmission).

Data from the line first passes to an amplitudeequalizer, which raises the level of frequencies aboveabout 1000 Hz, and lowers the level of frequenciesbelow about 1000 Hz. This makes the signal profile asflat as possible. The data is then filtered to removelow frequency noise (such as from the power supply)and high frequency noise (such as that caused byoverhead power lines for railways). The data thenpasses to the modem.

The modem demodulates the incoming data andconverts it to parallel.

TIP

RING

SpeakerVolume and

On/OffControl

FromtheNetwork

Modem

Equalizer

Filters

SAFMemory

ECMMemory

FIFOMemory

CPU

Rx-u.wmf



The data is extracted from the ECM data frames in the ECM memory and passed to the cpu for datareconstruction (the opposite of compression). If ECM is disabled, the data passes through the FIFOmemory instead of the ECM memory.

- Machines with SAF Memory -

Machines with SAF memory store the message in the SAF at the same time as the data passes tothe cpu for decoding. This protects against data being lost as a result of a printing error (such as ajam).If memory reception is used (e.g., confidential mode), the data is held in the SAF memory untilthe user prints the data.

Note: If transmitted signals are degraded because of the distance between the modem and the localexchange, try adjusting the cable equalizer. This is normally a bit switch adjustment.

Note concerning ECM

In receive mode, both buffers of the double buffer memory are used, so if a page has to be split intotwo blocks, the second block can be received while the first block is still being printed. (In transmitmode, only a single buffer is used; if a page has to be split into two blocks, the first block must besent and erased before the second block can be stored in the ECM memory)

ECM reception of MMR coded data—If the printer jams or runs out of paper while receiving thesecond block, the second block will be erased from memory. This is because the data at thebeginning of the second block cannot be reconstructed, as the line at the end of the first block hasalready been erased. An Error Report is printed, which contains a message for the user to contactthe sender for retransmission.



Others

Voice Message

Voice Message Types

There are two types of voice message thatcan be recorded. One is for use with theNotify function (to inform the Notifydestination that a fax message has come in),and the other is for use in Auto Receivemode (to warn any telephone caller that theyhave connected to a fax machine). In mostmodels, only the Auto Answer voice messageis available.

The diagram shows the circuits for storing,playing back, and transmitting a voicemessage.

To theNetwork

SpeakerVolume and

On/OffControl

Modem

ProgrammableResistorSelectSwitch

TIP

RING

Voice MessageProcessor

Memory

Speaker

MicrophoneRECORDING

PLAYBACK

TRANSMISSION

ProgrammableResistor

Attenuator

Voice-u.wmf



Storing the Voice Message

To record a voice message, the user speaks into the microphone, which is either in the handset orbuilt into the operation panel. The diagram on the previous page shows the circuit when amicrophone is used.

The signal is amplified. Then, it passes to the Voice Message Processor, which converts the voicesignal to digital and stores it in the memory. The voice message memory normally has battery back-up.

Note: In some models, the user speaks into the handset microphone. When the user selects voicemessage recording, a relay connects the handset microphone to the voice messageprocessor.

Playing Back the Voice Message

To play back a voice message, the Voice Message Processor reads the digitized message from thememory and converts it back to an audio signal. The signal is then amplified.

The signal passes through the speaker volume control, which the user can normally adjust. Thesignal is then amplified before going to the speaker.



Voice Message Transmission in Auto Receive Mode

If the Voice Message has been programmed and switched on, the unit sends it out immediatelybefore the CED tone if it does not receive CNG; if CNG is not received, the calling machine is not anautomatic dialing fax terminal. Total communication time is increased by the length of the voicemessage.

The Voice Message Processor converts the stored Voice Message into a voice signal. The VoiceMessage is attenuated and passed to the line in the same way as transmitted data.



Reception with Answering Machine

Overview

The answering machine is connected to therear of the fax machine, in the same place asa handset.

In standby mode, the Oh relay connects theanswering machine to the line. The hookswitch in the answering machine is open, sothere is no dc loop. However, the ringer in theanswering machine can detect ac ringingsignals coming from the local exchange.

+24V


LOCALEXCHANGE

Ringer

ANSWERINGMACHINE(Simplified)

OhRelay

Ansmach1.wmf



Answering Machine with Telephone

When an answering machine with a telephone answers anincoming call, the call proceeds as shown in the diagram.

When a ringing signal comes in from the local exchange,the answering machine starts to ring [A]. While theanswering machine is still ringing [B], the call can still beanswered if someone picks up the handset.

If by point [C] the handset has not been picked up, theanswering machine connects to the line and starts to sendthe pre-recorded message, with a beep at the end [D]. Thecaller then has a chance to record a message, before theline is disconnected [E].

(

9 August 2003

Reception

CallerTelephone)

Receiver(Telephone with

Answering Machine)

Dialling

End-to-end Delay

[A]

[B]

[D]Beep

[C]

Pre-recordedmessage

Recordingmode

[E]

Ansmach2.wmf

Page 563


Answering Machine with Fax Terminal

Auto Receive (Fax) Mode

When a ringing signal comes in [A], the answeringmachine starts ringing and the fax machine begins ringingsignal detection. As soon as the fax machine detects theringing signal, it closes the dc loop [B], disconnecting theanswering machine.

Therefore, as long as the fax machine closes the dc loopbefore the answering machine can react ([C] in thediagram on the previous page), the answering machinedoes not affect the fax machine's operation.

Caller

Dialling

End-to-endDelay

[A]

[B]Ringing

Receiver(Fax Terminal with

AnsweringMachine)

Fax communicationproceedsas normalfromthispoint

Ansmach3.wmf



Manual Receive (Tel) Mode

As just explained, the answering machine has no effect onthe fax machine when it is in Fax Mode. Therefore, the usermust set the fax machine up in Tel Mode to use ananswering machine. The operation of the fax machine thendepends on what type of equipment is calling it.

a) Receiving from a fax machine in automatic dial mode

First, the ringing signal comes in [A]. The fax machine is inmanual receive mode, so it ignores this. Because the faxmachine ignores the ringing signal, the answering machineanswers the line [B], and proceeds in the same way as if itwere connected to a telephone (see "2. Answering Machinewith Telephone").

The recorded message should contain the followinginstructions: "If you want to leave a recorded message,speak after you hear the beep. If you want to send a faxmessage, press 2 after you hear the beep, then press Starton your fax machine after you hear a high-pitched tone."(The number the person at the other end has to pressdepends on the answering machine.)

Dialling

End-to-endDelay

[A]

[B]

[D]

Beep

[C]

Pre-recordedmessage

RecordingmodeCNG

Receiver(FaxTerminal with

AnsweringMachine)

Caller(Auto-diallingFaxTerminal)

Answeringmachineis ringing

Fax communicationproceedsasnormalfromthispoint

Ansmach4.wmf



While this is going on, the other end sends CNG [C]. When the receiving fax machine detects CNG,it switches over the Oh relay to disconnect the answering machine [D], and closes the Di relay toconnect itself to the line.

The answering machine does not have any effect on the operation of the machine, unless there is aproblem with CNG detection.

If the fax machine cannot detect CNG, it cannot connect to the line. For example, CNG cannot bedetected if it comes in at the same time as the answering machine's recorded message is going out.Because of this, the best time for the fax machine to detect CNG is while the answering machine is inrecording mode, after sending out the beep (see the previous diagram).

Note: Some problems have been experienced in this area, as different types of terminal transmitCNG at different times, due to variations in interpretation of ITU-T recommendations.



b) Receiving from a fax in manual dial mode or atelephone

There is no CNG, so the answering machine hascontrol of the line. When the answering machinedetects a ringing signal [A], it sends out a recordedmessage. This message should contain the followinginstructions: "If you want to leave a recorded message,speak after you hear the beep. If you want to send afax message, press 2 after you hear the beep, thenpress Start on your fax machine after you hear a high-pitched tone." (The number the other end has to pressdepends on the answering machine; see the Note atthe end of this section.)

When the fax machine detects this '2' from the otherend [B], it switches over the Oh relay to disconnect theanswering machine, and closes the Di switch toconnect itself to the line [C]. Then it sends CED to thecaller [D]. When the caller hears this high-pitched tone,the caller presses Start [E], and fax-to-faxcommunication can go ahead.

Receiver(Telephone with

AnsweringMachine)

Dialling

End-to-endDelay

[A]

[B]

[D]

Beep

[C]

Pre-recordedmessage

Recordingmode

[E]

Caller(Telephone, orManual DiallingFax Terminal)

Ringingsignal comes in

Answering machineis ringing

'2'

CED

End-to-endDelay

'Start'

Ansmach5.wmf



The caller must use a DTMF tone dialingtelephone. The cpu detects the tone at [A].Then the cpu will switch the machine into autoreceive mode using [B], and the other end willbe able to send the fax message.

TIP

RING

RI

TI

Network

Oh Relay

+24VS

+5V

+5V

DTMF ToneDetector

[A]

[B]

AnsweringMachine

HookSwitch

CPU

Ansmach6.wmf



Remote Control

Remote control features do not use the same circuit to detect the codes input at the remotetelephone or fax machine. In remote control mode, the machine closes the dc loop, so DTMF tonesfrom the other end pass to the cpu along the same route as received fax data signals.

Using remote control, the fax machine is controlled from a remote location through the telephonenetwork using a telephone or fax machine. The user dials the fax machine and selects a feature byinputting some numbers. The fax machine then executes the selected function.

When the receiving machine detects a ringing signal, it closes the dc loop and sends out CED. Theuser at the other end then presses the required button on his ten-key pad, and transmits DTMF tonesto the receiver (the caller must use a DTMF tone dialing telephone or fax machine). The receivingside's cpu detects the DTMF tones.



European/Asian Models

Ringing Signal Detection

Monitoring the Line

The ringing signal detector is a circuitcontaining a photocoupler and some zenerdiodes. The cpu constantly monitors the output[A] for a ringing signal unless the printer is inuse or the dc loop is already closed.

An incoming signal switches the photocoupleron/off if the voltage is higher than a certainvoltage. The cpu analyzes the signal [A].

The circuit contains a variety of resistors,capacitors, and jumpers to ensure compliancewith a wide range of PTT requirements.

Network

[A]

Handset

RingingSignal

Detector

CPU

Rngdete1.wmf



Signal Analysis

A ringing signal must satisfy three basic criteria: frequency, number of rings, and continuity. In allmodels, the principles of ringing signal detection are the same. A few models differ slightly from theexplanation given below.

- Frequency -

When the cpu detects a signal, it measuresthe frequency. If the frequency is within thelimits specified by the parameters [A]programmed in the memory, the cpudetermines that it is a possible ringing signal.

- Number of Rings -

Ringing signals have a cadence, consistingof rings and intervals between rings, asshown on the previous page. The cpu countsthe rings.

However, the cpu does not increment the ring counter unless the ring was long enough. The first ringmust be longer than the interval [B], and subsequent ones must be longer than the interval [C].

A certain number of rings [D] must be detected before the cpu confirms that the incoming signal is aringing signal. When the count reaches the required value, the cpu confirms that the signal is a

One Ring

RingingSignal

[B] [C]

Ringing Signal,One Wavelength

[A]

[E]

Rngdete2.wmf



ringing signal. The machine then goes into receive mode, and the cpu turns on the power supply forall components.

- Continuity -

The ringing signal must also satisfy a continuity test. The time between the end of a ring and the startof the next ring must not exceed the interval [E]. Otherwise, ringing detection flags will be reset andthe next ring detected will be treated as the start of a new ringing signal.

Note: Parameters A to E described in this section can be adjusted.



DC Loop Closure

Auto Receive (FAX) Mode

After confirming the ringing signal, the cpu closes the dc loop by switching over the Oh relay thenturning on the Di or Ds relay. The timing is the same as for transmission. The machine sends CED tothe transmitting machine, to inform it that it has connected to a fax terminal.

Manual Receive (TEL) Mode

In manual receive (TEL) mode, automatic ringing signal detection and loop closure are not done. Theuser picks up the handset after hearing it ring; this closes the dc loop. The user then presses Startafter hearing the fax signal from the other end. Then the fax machine connects to the line by closingthe Di or Ds relay then switching over the Oh relay. The timing is exactly the same as for manualdialing.

Auto Select (AUTO) Mode

When the machine detects the ringing signal, it closes the dc loop in the same way as for AutoReceive Mode.

If the machine detects CNG (which means that the other end is an auto-dialing fax machine), it sendsout CED. From this point, the machine behaves in the same way as if it was in Auto Receive Mode.

If the machine does not detect CNG after 2 s, it will send out a voice message (if the machine hasthis function). Then, if CNG has still not come in within a certain time (let us call it [A]), the machine



will emit an alarm to alert the user. From this point, the machine must detect CNG or the user mustpick up the handset within a certain time (let us call it [B]). If the other party hangs up during thisinterval, the machine will also hang up.

If the interval [B] expires, the machine sends out CED. If the other party is a fax machine in manualdialing mode, the other party will press Start, and fax communication can go ahead in the same wayas for Manual Receive Mode. If the other party hangs up instead, this machine will also hang up.

Note: Timers A and B can be adjusted.



Data ReceptionThis section explains the path of data from thetelephone line to the cpu (non-memory transmission)or the SAF memory (memory transmission).

Data from the line first passes to an amplitudeequalizer, which raises the level of frequencies aboveabout 1000 Hz, and lowers the level of frequenciesbelow about 1000 Hz. This makes the signal profile asflat as possible. The data is then filtered to removelow frequency noise (such as from the power supply)and high frequency noise (such as that caused byoverhead power lines for railways). The data thenpasses to the modem.

The modem demodulates the incoming data andconverts it to parallel.

L1

L2

SpeakerVolume and

On/OffControl

FromtheNetwork

Modem

Equalizer

Filters

SAFMemory

ECMMemory

FIFOMemory

CPU

Rx-e.wmf



The data is extracted from the ECM data frames in the ECM memory and passed to the cpu for datareconstruction (the opposite of compression). If ECM is disabled, the data passes through the FIFOmemory instead of the ECM memory.

- Machines with SAF Memory -

Machines with SAF memory store the message in the SAF at the same time as the data passes tothe cpu for decoding. This protects against data being lost as a result of a printing error (such as ajam).If memory reception is used (e.g., confidential mode), the data is held in the SAF memory untilthe user prints the data.

Note: If transmitted signals are degraded because of the distance between the modem and the localexchange, try adjusting the cable equalizer. This is normally a bit switch adjustment.

Note concerning ECM

In receive mode, both buffers of the double buffer memory are used, so if a page has to be split intotwo blocks, the second block can be received while the first block is still being printed. (In transmitmode, only a single buffer is used; if a page has to be split into two blocks, the first block must besent and erased before the second block can be stored in the ECM memory)

ECM reception of MMR coded data—If the printer jams or runs out of paper while receiving thesecond block, the second block will be erased from memory. This is because the data at thebeginning of the second block cannot be reconstructed, as the line at the end of the first block hasalready been erased. An Error Report is printed, which contains a message for the user to contactthe sender for retransmission.



Others

Voice Message

Voice Message Types

There are two types of voice message that can berecorded. One is for use with the Notify function (toinform the Notify destination that a fax message hascome in), and the other is for use in Auto Receivemode (to warn any telephone caller that they haveconnected to a fax machine). In most models, onlythe Auto Answer voice message is available.

The diagram shows the circuits for storing, playingback, and transmitting a voice message.

9 August 2003

Reception

To theNetwork

SpeakerVolume and

On/OffControl

Modem

Attenuator

L1

L2


Memory

Speaker

MicrophoneRECORDING

PLAYBACK

TRANSMISSION

Voice-e.wmf

Page 577


Storing the Voice Message

To record a voice message, the user speaks into the microphone, which is either in the handset orbuilt into the operation panel. The diagram on the previous page shows the circuit when amicrophone is used.

The signal is amplified. Then, it passes to the Voice Message Processor, which converts the voicesignal to digital and stores it in the memory. The voice message memory normally has battery back-up.

Note: In some models, the user speaks into the handset microphone. When the user selects voicemessage recording, a relay connects the handset microphone to the voice messageprocessor.

Playing Back the Voice Message

To play back a voice message, the Voice Message Processor reads the digitized message from thememory and converts it back to an audio signal. The signal is then amplified.

The signal passes through the speaker volume control, which the user can normally adjust. Thesignal is then amplified before going to the speaker.



Voice Message Transmission in Auto Receive Mode

If the Voice Message has been programmed and switched on, the unit sends it out immediatelybefore the CED tone if it does not receive CNG; if CNG is not received, the calling machine is not anautomatic dialing fax terminal. Total communication time is increased by the length of the voicemessage.

The Voice Message Processor converts the stored Voice Message into a voice signal. The VoiceMessage is attenuated and passed to the line in the same way as transmitted data (see section 2-8for details).

Remote Control

Using remote control, the fax machine is controlled from a remote location through the telephonenetwork using a telephone or fax machine. The user dials the fax machine and selects a feature byinputting some numbers. The fax machine then executes the selected function.

When the receiving machine detects a ringing signal, it closes the dc loop and sends out CED. Theuser at the other end then presses the required button on his ten-key pad, and transmits DTMF tonesto the receiver (the caller must use a DTMF tone dialing telephone or fax machine). The receivingside's cpu detects the DTMF tones.


Facsimile Processes Fax Circuit Update

Fax Circuit Update

North American Models The descriptions in the Core Technology Manual (Facsimile Processes Transmission North American Models, Facsimile Processes Reception North American Models) are based on the C series models (H081 series). There have been a few small changes since these models.

Changed Names The following components have new names. There is no change in the function of these components. These new names took effect from the F/L series models (H516/H521 series).

Old New Oh relay CML relay, Relay Di switch OHDI switch

Changes to the Circuit In some NCUs, there is no Off-hook Detection circuit. DC Loop: This new circuit, between the OHDI switch and the exit to the fax main board prevents dc from entering the fax main board from the NCU. CML relay: In some NCUs, the wiring between this relay and the telephone line has been altered, but there is no change in how the machine dials out, because PTT requirements have not changed. Some example block diagrams are shown on the next few pages.



C series (H081 series): Old names, as used in the main text of the core technology manual



Schmidt 3 (H547): Changed names, but no changes to the circuits

Ring Detect

RING

TIP

OHDISW

Hook0

Hook1

Ex Ring

JP5

Ex TDIExt. TelDP/Off-Hook

Detection

CurrentSensor

24V

CMLSW

RITONE

Q6

Q5

Relay

24V

OHDISW

JP6

T1

R1

TRXD

NCU

BR1



Schmidt 4 (H535): Changed names, and changes to the circuits

TIP

RING

OHDISW.

JP8

CMLRelay

DB1

NoiseFilter

SurgeProtection

Over-current

Protection

TRXDL-

TransformerDC-Loop

SurgeProtection

JP7

Hook0

OHDISW

Hook1

ExRing

CMLSW

CurrentSensor

T1

T2

RingDetection

Circuit

NoiseFilter



European/Asian Models The fax circuit descriptions in the Core Technology Manual (Facsimile Processes Transmission European/Asian Models, Facsimile Processes Reception European/Asian Models) are based on the C series models (H081 series). There have been a few small changes since these models. These changes are listed below.

Changed Names The following components have new names. There is no change in the function of these components. These new names took effect from the F/L series models (H516/H521 series).

Old New Oh relay CML relay Di switch, Di relay OHDI switch Ds switch, Ds relay DO switch

Changes to the Circuit DC Loop: This new circuit, between the OHDI switch and the exit to the fax main board prevents dc from entering the fax main board from the NCU. ! In some NCUs, there is a control signal (DCLSW) to this DC Loop circuit. This signal adjusts the

maximum level of dc that passes out of the machine through the NCU to the line. In TBR21 nations, the limit is 60 mA. For other European nations, the limit is 120 mA.

Some example block diagrams are shown on the next few pages.



C series (H081 series): Old names, as used in the main text of the core technology manual



FX6 (H516): Changed names, but no changes to the circuits

TIP

RING

SHUNT

GS

T1

R1

TRXD

JP24

TIP

RING

SHUNT

GS

T1

R1

OHDISW

Hook0

RSEL

DOSW

CMLSW

Hook1

ExRing

CSEL0

CSEL1RingDetection

Circuit

CurrentSensor

Filter(16Hz)

CML Relay

DO Sw.

GSSW

OHDI Sw.

GS Sw.

CN5

Loop ClosureCircuit

CN7



Schmidt 4 (H535): Changed names, and changes to the circuits

TIP

RING

SHUNT

GS

T1

R1

TRXD

TIP

R1

SHUNT

GS

T1

OHDISW

Hook0

RSEL

DOSW

DCLSW

Hook1

ExRing

CSEL

CurrentSensor

Filter(16 kHz)

CML Relay

DO Sw.

GSSW

OHDI Sw.

GS Sw. CMLLSW

NoiseFilter

NoiseFilter Ring

DetectionCircuit

DC-Loop


Group 3 Fax Communication Compression Techniques

Compression Techniques

Overview

Compression and ReconstructionDigital machines compress image data for two purposes.• To reduce the amount of memory or hard disk space required for storage• To reduce the amount of time needed to transmit the image data by fax.

This section will deal mainly with fax data compression and reconstruction. For faxcommunication, data is compressed in accordance with internationally-agreed standards.However, for temporary storage on hard disk, other techniques may be used.

An analog facsimile machine takes a long time to transmit all the black and white pixels of ascanned original. Therefore, to reduce transmission time, the high-speed facsimile compressesthe scanned data before transmission.

Compression: Reduces the volume of scanned dataReconstruction: Converts the compressed data back into the original data



Encoding Scheme for CompressionIf an A4-size document (216 mm x 297 mm, very approximately equal to a Letter size document)is scanned at standard resolution (8 dots per mm across the page and 3.85 dots per mm downthe page), a large number of pixels are generated. The actual number is:

216 x 8 x 297 x 3.85 = 1,975,882 pixels.

If these pixels are sent out at 9,600 bits per second, it takes about 3 minutes and 40 seconds tosend the page.

To reduce this time, an encoding system was developed to achieve high-speed transmissionwhich reduces the transmission time to 1/6 - 1/7th of that required for uncompressed data.

Modified Huffman (MH) coding is the basic compression technique for facsimile datatransmission. It looks at run lengths, that is, the consecutive numbers of pixels that have thesame color.

For example, if a sample of data is "white, white, white, black, black, black", it can be consideredas "3 white, 3 black". Modified Huffman coding specifies a code of "1000" for "3 white", and "10"for "3 black".

The designers of MH coding determined the most common run lengths and gave them theshortest codes; “3 black” is one of the most common sequences. Less frequent run lengths weregiven longer codes. In this way, a code table was constructed with regard to the variousoccurrence rates of run lengths, to minimize the total number of bits in the transmitted data.



The ITU-T T.4 recommendation contains the run length code tables, as shown on the followingpages. The code table consists of "terminating codes" to replace run lengths of 0 to 63, and"make-up codes" to replace run lengths of multiples of 64 bits. Scanned data is compressed byreplacing each run length with either:

• A terminating code (for black or white run lengths less than 64)

• A make-up code followed by a terminating code (for black or white run lengths of 64 orgreater)

Terminating Codes

White Run Length Black Run Length0 00110101 0 00001101111 000111 1 0102 0111 2 113 1000 3 104 1011 4 0115 1100 5 00116 1110 6 00107 1111 7 000118 10011 8 0001019 10100 9 00010010 00111 10 000010011 01000 11 000010112 001000 12 000011113 000011 13 0000010014 110100 14 00000111



White Run Length Black Run Length15 110101 15 00001100016 101010 16 000001011117 101011 17 000001100018 0100111 18 000000100019 0001100 19 0000110011120 0001000 20 0000110100021 0010111 21 0000110110022 0000011 22 0000011011123 0000100 23 0000010100024 0101000 24 0000001011125 0101011 25 0000001100026 0010011 26 00001100101027 0100100 27 00001100101128 0011000 28 00001100110029 00000010 29 00001100110130 00000011 30 00000110100031 00011010 31 00000110100132 00011011 32 00000110101033 00010010 33 00000110101134 00010011 34 00001101001035 00010100 35 00001101001136 00010101 36 00001101010037 00010110 37 00001101010138 00010111 38 00001101011039 00101000 39 00001101011140 00101001 40 00000110110041 00101010 41 000001101101



White Run Length Black Run Length42 00101011 42 00001101101043 00101100 43 00001101101144 00101101 44 00000101010045 00000100 45 00000101010146 00000101 46 00000101011047 00001010 47 00000101011148 00001011 48 00000110010049 01010010 49 00000110010150 01010011 50 00000101001051 01010100 51 00000101001152 01010101 52 00000010010053 00100100 53 00000011011154 00100101 54 00000011100055 01011000 55 00000010011156 01011001 56 00000010100057 01011010 57 00000101100058 01011011 58 00000101100159 01001010 59 00000010101160 01001011 60 00000010110061 00110010 61 00000101101062 00110011 62 00000110011063 00110100 63 000001100111



Make-up codesWhite Run Length Black Run Length

64 11011 64 0000001111128 10010 128 000011001000192 010111 192 000011001001256 0110111 256 000001011011320 00110110 320 000000110011384 00110111 384 000000110100448 01100100 448 000000110101512 01100101 512 0000001101100576 01101000 576 0000001101101640 01100111 640 0000001001010704 011001100 704 0000001001011768 011001101 768 0000001001100832 011010010 832 0000001001101896 011010011 896 0000001110010960 011010100 960 000000011100111024 011010101 1024 00000011101001088 011010110 1088 00000011101011152 011010111 1152 00000011101101216 011011000 1216 00000011101111280 011011001 1280 00000010100101344 011011010 1344 00000010100111408 011011011 1408 00000010101001472 010011000 1472 00000010101011536 010011001 1536 00000010110101600 010011010 1600 0000001011011



White Run Length Black Run Length1664 011000 1664 00000011001001728 010011011 1728 0000001100101EOL 000000000001 EOL 000000000001

Note: A scan line for A4-width paper at the normal 8-pixel/mm resolution requires 1728 bits.However, some machines can scan wider paper. The following table gives the make-upcodes used for wider paper.

Additional make-up codes for wide paper

Run Length(White or Black)

Make-up codes

1792 000000010001856 00000011001920 000000011011984 0000000100102048 0000000100112112 0000000101002176 0000000101012240 0000000101102304 0000000101112368 0000000111002432 0000000111012496 0000000111102560 000000011111



Modified Huffman (MH) Method

One-dimensional CodingMH coding is often referred to as a “one-dimensional” coding scheme. This refers to the fact thatMH codes the data on a scan line without referring to the data on adjacent lines. Modified Read(MR) coding uses a reference scan line to encode the scan line, and is thus known as “two-dimensional” coding.

MR coding is dealt with in a later section. This section explains how MH coding is implementedin facsimile communications.

Encoding Example The following diagram shows a 1728-bit scan line. If MH coded, "10 white" is encoded as"00111", "5 black" as "0011", "3 white" as "1000", "2 black" as "11", and "1708 white" as acombination of the make-up code for 1664 white ("011000") and the terminating code for 44white ("00101101").

1 Scan Line (1728 bits)

...

W10"00111"

B5"0011"

W3"1000"

B2"11"

W1708W1664 + W44

"011000" "00101101"

040101.vsd



All data lines begin with a white run length, in order for the receiving terminal to ensuresynchronization of color. If, however, the actual scan begins with a black run length, a white runlength with length of 0 is transmitted.

End of line encoding (EOL)EOL (End of Line) : 000000000001

At the end of each scan line of data, an EOL code is added. This is a unique code than cannever be generated within a line of MH coded data. EOL ensures that the communicatingmachines can resynchronize if a noisy telephone line causes data errors. There is also an EOLat the start of the page, before the first line.

The receiving terminal uses the following rules to reconstruct the line of original data betweenEOL codes:

• EOL is always followed by a white run length.

• A black run length always follows a white run length, and a white run length always followsa black run length.

• A make-up code is always followed by a terminating code.

• The number of bits in a scan line is either 1,728 (for A4 size), 2,048 (for B4 size), or 2,376(for A3 size).



Fill DataFill data: A variable length string of 0s.

Using MH coding, it is possible that a line of encoded data is very short, and the next line is sentout before the receiving machine has processed that short line of data. To solve this problem,each line must take a minimum time to send. This must equal the receiver’s I/O processing time.If the line of data ends before the I/O processing time, fill bits (all zeroes) are inserted betweenthe encoded data and the EOL code until the I/O processing time is reached.

EOLCodedData

EOL Fill EOLCodedData

CodedData

C>N C<N

C≥N

C: Coded Data (includes EOL)N: Minimum bit quantity

040102.vsd



The I/O processing time is determined as a minimum number of bits as shown in the followingtable. It depends on the modem transmission rate, the I/O rate (for an A4-width scan line), andthe paper width.

I/O rate 40 ms 20 ms 10 msPaper Width A4 B4 A4 B4 A4 B4Modem rate9,600 bps 193 229 97 1157,200 bps 145 173 73 874,800 bps 193 229 97 115 49 592,400 bps 96 115 49 59 25 31



Return to Control (RTC)The end of a page is indicated by transmitting six consecutive EOL codes. This is known as RTC(return to control).

EOL Data Fill EOL

<T≥Τ T: Minimum transmission time of a total coded scan line

EOL Data Data

≥Τ

EOLData EOLEOL Data EOL EOL EOL EOL

RTC

Several scan lines of data at the beginning of a page.

Last coded scan line of a page

Post messagecommand

040103.vsd



Recommendation T.4 includes the following descriptions:

• Minimum transmission time per line (also known as the I/O rate)

‘One line’ refers to one encoded scan line and is defined as the sum of data bits,required fill bits, and EOL bits.

a. 20 milliseconds : recommended standard

b. 40 milliseconds : approved option.10 milliseconds : approved option.5 milliseconds : approved option.

These are applicable to standard resolution (3.85 lines/mm down the page) and highresolution (7.7 lines/mm).

• Maximum transmission time per line

The maximum transmission time per one encoded scan line is 5 seconds. When thetransmission time exceeds 5 seconds, the receiving terminal must proceed todisconnect the line.

• Encoding system

Two encoding systems are available: a one-dimensional run length encoding method(MH) and a two-dimensional encoding method (MR), which is approved as an option.

ITU-T Recommendation



Modified Read (MR) Method

OverviewThe MR method is an expanded form of the one-dimensional run length encoding method and isconsidered an option of that encoding method. The method is described in detail in this section.

While the MH method encodes pixels in the pixel scanning direction, the MR method also takesnotice of the pixels running in the feed direction. The MR method compares the pixels in thecurrent line with the pixels in the preceding line, and transmits information on the relationshipbetween these two lines.

When dealing with relatively simple characters such as those contained in the alphabet,encoding based on the MH method remains effective. However, when dealing with morecomplex characters, like Chinese-based characters, the encoding efficiency falls. This is wherethe two-dimensional coding method, the MR method, is more effective. The MR encodingmethod bases itself on the Relative Address Designation Encoding Method (READ) whichcombines NTT's Edge Different Coding (EDIC) method and KDD's Relative Address Coding(RAC) method. Slight modifications were made to this method.

In two-dimensional coding, the first line is MH coded, and is treated as a reference line forcoding the second line. The second line is expressed as the difference between itself and thereference line. Then, the second line becomes the reference line for the third line, and so on.



K ParameterThe weakness of this method is that if an error occurs, all data after the line with the error will bedecoded wrongly, and the rest of the page will be garbled. To counter this, a limit is placed onthe number of consecutive lines that are MR coded. When this limit is reached, the next line isMH coded, and this line becomes the reference line for the next block of consecutive MR-codedlines. In this way, if an error occurs, only the block containing the error will be lost.

The limit on the number of consecutive MR-coded lines is the K parameter. Every Kth line is MHcoded. Following each MH-coded line, the number of consecutive MR-coded lines is K-1. Themaximum K value is as shown below:

• Standard vertical resolution (for regular characters): K = 2• Optional higher resolution (for fine characters): K = 4


Group 3

Two-diIn two-dare codeither oline)

Changi

Changithe sam

a0: Refa1: Firsa2: Firsb1: Firsb2: Firs

9 August 2

Fax Communication Compression Techniques

mensional Encoding Schemeimensional coding, the positions of pixels that change color (known as changing pixels)ed with respect to the position of a reference element. The reference element can ben the coding line (the line being coded) or on the reference line (directly above the coding

ng Pixels

ng pixels are pixels with color (black or white) different to the pixel immediately before one line. See the following diagram.

erence or initial changing pixel along the coding linet changing pixel to the right of a0 on the coding linet changing pixel to the right of a1 on the coding linet changing pixel on the reference line to the right of a0 and of opposite color to a0t changing pixel to the right of b1 on the reference line

040102.tifChanging pixels

Reference line

Coding line

003 Page 603


Coding Modes

When encoding the position of a changing pixel on the coding line, one of the three modesshown below must be selected.

• Pass Mode• Vertical Mode• Horizontal Mode

- Pass Mode -

If b2 is to the left of a1, pass mode is used. The pixel is represented by the code for Pass Mode(0001; see the Two-dimensional Code Table later in this section). After encoding, a0 becomesthe pixel directly beneath b2, to prepare for the next encoding procedure.

Note that if b2 is located directly above a1, pass mode is not selected (see the followingdiagrams).

040103a.tif

Reference line

Coding line

Pass mode



- Vertical Mode -

Vertical mode is used if the distance between a1 and b1 is three pixels or fewer.

The pixel is represented by one of the following codes: V(0), VR(1), VR(2), VR(3), VL(1), VL(2),VL(3). The appended characters, R and L, represent whether a1 is to the right or the left of b1,while the figures in parentheses represent the distance. The codes are listed in the Two-dimensional Code Table (later in this section).

After encoding in vertical mode, a0 is set in the a1 position to prepare for the next encodingprocedure.

040103b.tif

Reference line

Coding line

Not pass mode



- Horizontal Mode -

Horizontal mode is used if the distance between a1 and b1 is more than three pixels.

In this mode, the run lengths a0a1 and a1a2 are encoded by the following formula:

H + M (a0a1) + M (a1a2)

H is the horizontal mode flag code 001. M (a0a1) and M (a1a2) represent the run length andcolor of each, and are encoded using one-dimensional coding.

After encoding in horizontal module, a0 is set in the a2 position.

040104a.tif

Reference line

Coding line

Horizontal mode

Vertical mode

Vertical Mode and Horizontal Mode



The following table shows the codes used in the three modes explained above.

Two-dimensional Code Table

Mode Elements to be coded Notation Code word

Pass b1, b2 P 0001

Horizontal a0a1, a1a2 H 001+ M(a0a1) + M(a1a2 )

a1 just under b1 a1b1 = 0 V(0) 1

a1b1 = 1 VR(1) 011

a1b1 = 2 VR (2) 000011

a1 to the right of b1

a1b1 = 3 VR(3) 0000011

a1b1 = 1 VL(1) 010

a1b1 = 2 VL(2) 000010

Vertical

a1 to the left of b1

a1b1 = 3 VL(3) 0000010



Coding Procedure

Coding is conducted in accordance with the flow chart shown in the Two-dimensional coding flowdiagram on the next page.

When the required coding mode has been identified (using Step 1 or 2 as explained below), thecode word is selected from the Two-dimensional Code Table on the previous page.

Step 1

• If a pass mode is detected, this is coded as 0001. Then, a0 is set directly beneath b2 toprepare for the next encoding procedure.

• If a pass mode is not detected, go to step 2.

Step 2

• If the distance between a1 and b1 is three or fewer pixels, vertical mode is used. Then, a0is set in the a1 position to prepare for the next encoding procedure.

• If the distance between a1 and b1 is more than three pixels, horizontal mode is used.Then, a0 is set in the a2 position to prepare for the next encoding procedure.



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Processing the first and last pixels in a line

(A) Processing the first pixel

The first initial reference pixel a0 along each coding line is imagined to be immediately beforethe first pixel and is considered to be a white pixel.

The first run length a0a1 is replaced by a0a1 - 1. Therefore, when the first run is black, and theline is encoded using horizontal mode, then M(a0a1) corresponds to a white run of zero length.

(B) Processing the last pixel

The machine continues until it has encoded the position of the changing pixel imagined to beimmediately after the last actual pixel. This pixel is encoded either as a1 or a2. Also, if b1 and/orb2 are not detected on this line, they will be placed on the imaginary changing pixel immediatelyafter the last actual pixel on the reference line.

Line synchronization code

EOL will be added at the end of the line. After the EOL, a tag bit will be added to indicatewhether one-dimensional encoding or two-dimensional encoding will be used for the next line.

EOL + 1: The next line will go through one dimensional encoding.

EOL + 0: The next line will go through two dimensional encoding.



Fill

To ensure that the encoded data is not shorter than the per-line minimum transmission time, fillwill be inserted between the data and the line synchronization code. Fill bits are not inserted inthe middle of data.

Format : Variable length string of 0s

Return to control (RTC)

At the end of a page, six EOL + 1 signals are transmitted.



Summary

In summary, transmitted data will look something like the following after MR coding.

At the end of the page, the data will appear as follows.

Mrsumm1.wmf

Mrsumm2.wmf



Simple Modified Read (SMR) MethodThis is the same as MR coding except that K is 8 for Standard and Detail resolution, and 16 forFine resolution. This compresses data more effectively, but more data will be lost if line errorsoccur.



Modified MR (MMR) Method

The modified MR (MMR) encoding method uses the same algorithm as the MR methodexplained previously. The differences between the MMR and MR methods are as follows:

i. K parameter = ∞ : This means that all lines are encoded by two-dimensional encoding. Thefirst line of the page, the reference line, is a white line added to the top of the page, and MHcoded. All lines on the page are coded with reference to this imaginary white line.

ii. EOL is the line synchronization signal.

iii. No fill bits are used.

iv. RTC: Transmission of two consecutive EOL signals (also known as EOFB)

v. After EOFB, when it is necessary to arrange the information into a certain block size (such asto make up a complete ECM data frame), pad bits are added. Pad bits are a variable lengthrow of 0s.

vi. If there is a change in coding mode from MMR to something else, an ‘extension code’ is used.The format of the extension code is 0000001xxx, where xxx depends on which coding mode isused instead of MMR after the extension code.

Because an error can result in the loss of a lot of data, MMR is only used where datatransmission is highly reliable, such as on high-quality digital networks (Group 4 Facsimile), or ifECM is in use. MMR may also be used when storing data to SAF memory, for the most efficientuse of the memory space.



Estimated Fillbit Control (EFC)

OverviewEstimated Fillbit Control (EFC) was developed by Ricoh to improve the efficiency of MH, MR,and MMR coding. To reduce transmission time, EFC controls the number of fill bits inserted atthe end of each line of compressed data.

EFC is not strictly a compression technique, but it improves the efficiency of data transfer bycontrolling the number of fill bits inserted by the transmitter at the end of each line of data.

There are several proprietary EFC techniques on the market. The techniques used by thismanufacturer include EFC, New EFC, and SSC (Super Speed Coding).

Basic EFCThis method works as follows: while data is being received into memory, it is passes through aFIFO (first-in first-out) memory. However, because of memory capacity limitations, thetransmission side must be controlled so that the FIFO memory in the receiving terminal will notoverflow. The transmission side controls the number of fillbits by estimating the status of thereceiver’s memory.

For the MH method, the minimum number of bits (number of bits per line after encoding + fillbits) is defined by the following equation:

• Minimum no. of bits = (Modem speed x I/O rate) + 1

However, with the EFC method, the minimum number of bits is such that:

• Minimum no. of bits ≥ Modem speed x Minimum reproduction processing time



The I/O rate shows the time needed by the receiver to process a line, but the full duration maynot always be needed, so:

• I/O speed ≥ Minimum reproduction processing time

Therefore, the number of fillbits will be smaller than with the MH or MR method. Consequently, itis possible to achieve a reduction in transmission time.

Furthermore, EFC comes in two kinds, EFC and New EFC. While machines with EFC capabilitycan exchange a page in 13 seconds, a boosted buffer memory allows machines with New EFCto transmit a page in 12 seconds (from memory to memory).

EFC Without Consecutive Flag TransmissionThis is also known as EFC plus Short Preamble.

This method is an improvement in terms of transmission control. With the preamble set at onesecond, transmission time is further reduced.

The receiving terminal can ignore carrier interruption signals transmitted from the modem untildata processing within the memory is completed.

Normally, the post-message command can be received immediately after the page of imagedata.. However, depending on the contents of the data, processing the data stored in thereception memory takes some time, occasionally causing the post-message command to bereceived only on the second try.



Super Speed Coding (SSC) Method

The Super Speed Coding (SSC) method combines EFC plus Short Preamble and white linedouble-speed processing to achieve a further reduction in transmission time.

White-Line Double Speed ProcessingWhen the data is all white, this method reduces the minimum number of bits to half that of theconventional bit number.

On the reception side, when a white line is transmitted, the printer motor is fast forwarded to skipthe line.

Both terminals must have this feature, or it will not work.



JBIG Method

What is JBIG?JBIG (Joint Bi-Level Image Expert Group) is a working group which consists of members of ITU-T T.82 and ISO11544. The JBIG compression method allows lossless compression of bi-level(black-and-white) images. Data compression is approximately 1.2 to 1.3 times better than theMMR method in text mode, and 2 to 10 times in halftone mode.

How is it Done?JBIG compression consists of four processes:

• Conversion to bi-level data (if the original data is more than one-bit-per-pixel (i.e., if the outputcontains greyscales)

• Progressive coding (sending a low resolution image first, then increasing the resolution bysending more data to enhance the image)

• Division into stripes• Coding (using a process known as ‘arithmetic coding’)

Conversion to Bi-level Data

Multi-level data is converted to bitplanes using a process known as Grey coding. Each bitplaneconsists of an image made up of bi-level pixels (0 or 1). Each bitplane will then undergo theremaining steps of the JBIG compression process.



The number of bitplanes generated increases with the number of greyscales in the image.Because of this, if there are more than 8 bits per pixel, other compression techniques may bemore efficient than JBIG.

Progressive CodingWith progressive coding, an image is sent gradually instead of all at once. A low resolutionimage is sent first, then more detail is sent, and the receiver can progressively build up a higher-resolution image. With JBIG, the resolution doubles with each level of detail.

Division into Stripes

The image is then divided into stripes, and each stripe is coded and sent separately. There aretwo modes for JBIG compression.

• Standard mode: The transmitted data stripe consists of 128 lines.• Optional mode: the transmitted data stripe consists of one page (transmission speed with this

mode is faster).

The mode used is determined during handshaking, and can be set by bit switch adjustments.

Coding

MH, MR, and MMR are based on run-length coding. JBIG is based on a different process, knownas ‘arithmetic coding’. Arithmetic coding is done by a device known as a ‘Q-coder’.

Arithmetic coding looks at the patterns of pixels (known as ‘contexts’) surrounding each pixel.The algorithm contains a library of contexts, and for each context, there is a prediction as to



whether the central pixel is black or white. For example, if the context consists of all white pixels,it is likely that the target pixel is also white.

As for MH coding, the Q-coder assigns short codes to the most probable combinations of pixels,and long codes to the least likely combinations. In this way, maximum compression is achieved ifeach target pixel is always equal to the predicted pixel value for their context.

Other Points about JBIG

When is JBIG used?

JBIG compression is disabled when any of the following conditions occur.

• When JBIG compression is turned off• When ECM is turned off• When the receiving terminal does not have the JBIG feature.• When the receiving terminal does not have the ECM feature.

What is the Data Format?

JBIG compressed data is referred to as a Bi-level Image Entity (BIE).

The BIE consists of a header frame (BIH: Bi-level Image Header) and a compressed dataframe (BID: Bi-level Image Data).

BIH(Bi-Level Image

Header)

BID(Bi-Level Image Data)

Image Data Header

BIE: Bi-level Image Entity

a693d531



The BIH frame contains information such as main scan width (pixels), sub-scan length, andcompression mode (standard/optional).

The BID frame contains the actual data.

What are the Strengths and Weaknesses?

Strengths

• Superior compression for bi-tonal images than MMR, especially for complex images containingshading for example.

• Smaller files for greyscale images than JPEG.

Weaknesses

• Takes twice as long to decompress as Group 4 MMR.• JPEG is better for photographs


Group 3 Fax Communication Modulation Techniques

Modulation Techniques

Introduction

Fax machines communicate with each other by emitting a wave of a certain frequency onto thetelephone line. This wave is called the carrier. The data signal from the fax machine is known asthe modulating signal. To transmit data using this carrier wave, the fax machine superimposesthe modulating signal onto the carrier wave by varying the frequency, amplitude, or phase (or acombination of these) in a standard manner. This process is known as modulation. Themachine receiving this modulated signal can recover the original data by demodulating thesignal. Demodulation also includes noise removal and compensation for distorted waveforms.

A device called a modem carries out modulation and demodulation. The modem outputs thecarrier wave. The characteristics of the carrier wave are based on the following formula.

E = A sin (2πft + θ) A: Amplitude, f: Frequency, θ: Phase, t: Time, E: Output

The modem transmits data by modulating either A, f, or θ, or a combination of these.

For example, the V.29 modem sending at 9,600 bps modulates A and θ. The frequency of thewave is fixed at 1,700 Hz. At any point on the wave, the wave has one value of A and one valueof θ. The V.29 modem can output 2 possible values of A and 8 possible values of θ. This meansthat the V.29 modem can output 16 different waves. Each of these 16 waves can be made torepresent a different combination of bits; 0000, 0001, 0010, and so on up to 1111 can berepresented with a unique waveform.



A simple example of how a V.29 modemconverts digital data into an analog signal isillustrated here. The receiving modem decodesthe signal by measuring the amplitude of thewave and the phase of the wave at the start ofeach Baud.

Baud Rate

Each of the individual waveforms shown in theprevious diagram is known as a Baud. TheBaud rate is the number of bits per seconddivided by the number of bits per Baud. For a9600 bps (bits per second) modem, each Baudrepresents 4 bits. Therefore, the Baud rate is2400. This means that the V.29 9,600 bpsmodem sends out 2,400 waveforms per second.

Another way to think of the Baud is that it is thenumber of times per second that the signal fromthe modem changes.

Do not confuse the Baud rate with bps whenconsidering the machine's data speed.

9600bpsDigital Data

0011 1000 1001Modem

OneBaud

1700Hz

0011 1000 1001

Modem1.wmf



Generally, public telephone networks can only communicate using frequencies that are withinthe voice band, that is, between 300 and 3,400 Hz. Therefore, the carrier wave must besomewhere within these limits (the frequency of the carrier differs depending on the modulationmethod used).

In facsimile communication, several types of modulation are used. This section will describethese methods briefly. Details of the methods are given in the following ITU-T recommendations.

• V.21: Specifies conditions for signalling (protocol signals) at 300 bps, using frequency shiftkeying (FSK).

• V.27ter: Specifies conditions for signalling (fax data) at 2,400 and 4,800 bps, using polyphaseshift keying (PSK).

• V.29: Specifies conditions for signalling (fax data) at 7,200 and 9,600 bps, using quadratureamplitude modulation (QAM).

• V.32/V.17: Specifies conditions for signalling (fax data) at 9,600 bps using trellis codemodulation (TCM); this is used in machines that communicate at speeds of up to 14,400 bps,if they have to step down to 9,600 bps.

• V.33 (V.32bis)/V.17: Specifies conditions for signalling (fax data) at 12,000 and 14,400 bps.

• V.8/V.34: Specifies conditions for signalling (fax data) at up to 28,800 bps

• V.8/V.34bis: Specifies conditions for signalling (fax data) at up to 33,600 bps



As will be seen, a more complex modulation type allows more information to be carried on the samewave, which leads to a higher data speed. This is illustrated by the fact that the data rate for the9,600 bps modem is higher than for the 7,200 bps modem, even though the Baud rate is the same(refer to Quadrature Amplitude Modulation).

Note

• bps is the data rate in bits per second

• Hz (Hertz) is the frequency of a wave in cycles per second



V.21–Frequency Shift Keying (FSK)

Frequency shift keying (FSK) is a type offrequency modulation that is used fortransmitting digital signals. In basicfrequency modulation (FM), the modulatingsignal changes the frequency of the carrierwave. In the example in the diagram, ananalog signal is modulating the carrierwave. Notice how the phase of the wavechanges when the value of the data signalchanges from 0 to 1 and from 1 to 0.

In fax machines, the modulating signal is a 300 bps digital signal (for example, an NSF protocolsignal). Fax machines use the FSK method outlined in ITU-T recommendation V.21. If the signalis a 0, the transmitted frequency is 1,850 Hz. If the signal is a 1, the transmitted frequency is1,650 Hz.

The Baud rate is 300 Baud, and there is only one bit per Baud.

Fm.wmf



V.27TER–Polyphase Shift Keying (PSK)

OverviewPolyphase shift keying (PSK) is a type ofphase modulation (PM). In PM, data ismodulated by altering the phase of the carrierwave. The frequency is kept constant. Seethe diagram for a simple example. A one isrepresented by a 180 ° phase shift, and azero is represented by the phase staying thesame.

PSK under the V.27ter specifications uses a carrier frequency of 1,800 Hz. However, the datarate of 4,800 bps is considerably faster than the carrier wave frequency. To fit the data onto thecarrier wave, the carrier wave must be modulated in such a way that more than one bit is beingtransmitted at any time.

To do this, V.27ter specifies two types of phase modulation.

Pm.wmf



PSK at 2,400 bpsData is sent two bits at a time. The phase of the signal is varied in accordance with the data.There are four possible signals, as shown in the following table.

Two-bit value Phase00 0 °01 90 °11 180 °10 270 °

PSK at 4,800 bpsData is sent three bits at a time. The phase of the signal is varied in accordance with the data.There are eight possible signals, as shown below.

Three-bit value Phase Three-bit value Phase001 0 ° 111 180 °000 45 ° 110 225 °010 90 ° 100 270 °011 135 ° 101 315 °

The two-bit and three-bit groups described above are known as Bauds. The Baud rate is thenumber of Bauds transmitted per second. Do not confuse the data rate with the Baud rate.



Using V.27ter PSK, at a data rate of 2,400 bps, the Baud rate is 1,200 Baud, and at 4,800 bps,the Baud rate is 1,600 Baud.

Note: In PM, the phase change is the actual change in the signal phase between a Baud andthe Baud following it.

SummaryV.27 PSK modulation is summarized in the following table.

ModemType

DataSpeed

CarrierFreq.

BaudRate

ModemType

Eye Pattern

V.27 ter 4800 bps 1800 Hz 1600Baud

8 φ PSK

0

45

90

135

180

225

270

315

001

000

010

011

111

110

100

101

Psk1.wmf



ModemType

DataSpeed

CarrierFreq.

BaudRate

ModemType

Eye Pattern

V.27 ter 2400 bps 1800 Hz 1200Baud

4 φ PSK

0

90

180

270

00

01

11

10

Psk2.wmf



V.29–Quadrature Amplitude Modulation (QAM)

OverviewQuadrature amplitude modulation (QAM) is acombination of amplitude modulation (AM) andphase modulation (PM).

PM has already been described (see the previoussection). In AM, the amplitude of the wave varieswith the data signal. In the following example, adigital signal modulates the carrier. The amplitudeis high when the digital signal is at 1, and lowwhen it is 0. The frequency is kept constant.

AM is a relatively simple technique, however, it is susceptible to noise.

QAM under the V.29 specifications uses a carrier frequency of 1,700 Hz. V.29 specifies twotypes of modulation.

Am.wmf



QAM at 9,600 bpsData is sent four bits at a time. The phase and amplitude of the signal are varied in accordancewith the data. There are 16 possible signals, as shown in the following table.

Four-bit value Phase Amplitude0001 0 ° 30000 45 ° √20010 90 ° 30011 135 ° √20111 180 ° 30110 225 ° √20100 270 ° 30101 315 ° √21001 0 ° 51000 45 ° 3√21010 90 ° 51011 135 ° 3√21111 180 ° 51110 225 ° 3√21100 270 ° 51101 315 ° 3√2



QAM at 7,200 bpsData is sent three bits at a time. There are eight possible signals.

Three-bit value Phase Amplitude001 0 ° 3000 45 ° √2010 90 ° 3011 135 ° √2111 180 ° 3110 225 ° √2100 270 ° 3101 315 ° √2

The phase change in the above tables refers to the actual change in the signal phase between aBaud and the Baud following it. The amplitude in the above tables is a relative amplitude value.

Note: V.29 also gives a recommendation for faxing at 4,800 bps. However, in fax machines,V.27ter modulation is used at this data rate.



SummaryV.29 QAM is summarized in the following table.

ModemType

DataSpeed

CarrierFreq.

BaudRate

ModemType

V.29 9600 bps 1700 Hz 2400Baud

16ptQAM

9 August 2003


Eye Pattern

0

45

90

135

180

225

270

315

1010

0010 1000

00000001 1001

0101

1101

0100

1100

0110

1110

1111 0111

1011

0011

√2

3 2√

35

qam1.wmf

Page 634


ModemType

DataSpeed

CarrierFreq.

BaudRate

ModemType

V.29 7200 bps 1700 Hz 2400Baud

8 φQAM

9 August 2003


Eye Pattern

0

45

90

135

180

225

270

315

√23

001000

010

011111

110

100

101

Qam2 wmf

Page 635


V.17/V.32–Trellis Code Modulation (TCM)

Trellis code modulation (TCM) uses QAM. However, part of the data signal is encoded, usingTrellis Coding, for error correction purposes.

TCM at 9,600 bpsThe data signal is divided into groups of 4 bits (Q1, Q2,Q3, Q4). The first two bits of the group (Q1, Q2) areencoded into Y1 and Y2. The result of the encodingdepends on the previous Y1 and Y2 bits.

Y1 and Y2 are then encoded again. Y1 and Y2 emergeunchanged, but an extra 'redundant' bit Y0 has beengenerated. The original four bit group has been convertedinto a five-bit group. The algorithm for generating Y0, Y1,and Y2 is rather complex, and is known as Trellis Coding.Please refer to the ITU-T V.32 and V.32bisrecommendations for full details.

The five-bit group is then modulated by QAM inaccordance with the following diagram (the array of dotsis known as a ‘signal constellation’). The five-bit groups inthe diagram are listed in the following order: Q4, Q3, Y2,Y1, Y0.

2

4

2 4

-2

-4

-2-40

90

180

270

00011

01010

00101

11000

10100

11001

10110

10111

01000

01011

11111

00010

01001

00000

10101

11110

10011 01111

11100 10010 01100 11010 00100

00001 11101 10001 10110

01110 10000 00110

00111 11011

Tcm.wmf



TCM at 12,000 bps (V.32 bis)The data signal is divided into groups of 5 bits (Q1, Q2, Q3, Q4, Q5). The first two bits of thegroup (Q1, Q2) are converted to three bits (Y0, Y1, Y2) in the same way as for TCM at 9,600 bps(see above). The original five-bit group is now a six-bit group.

The six-bit group is then modulated by QAM in a similar way to that shown on the previous pagefor TCM at 9,600 bps. A similar diagram can be drawn, but for TCM at 12,000 bps, there are 64points on the diagram.

TCM at 14,400 bps (V.32 bis)The data signal is divided into groups of 6 bits (Q1, Q2, Q3, Q4, Q5, Q6). The first two bits of thegroup (Q1, Q2) are converted to three bits (Y0, Y1, Y2) in the same way as for TCM at 9,600 bps(see above). The original six-bit group is now a seven-bit group.

The seven-bit group is then modulated by QAM in a similar way to that shown on the previouspage for TCM at 9,600 bps. A similar diagram can be drawn, but for TCM at 14,400 bps, thereare 128 points on the diagram.

Note: For all three data rates discussed in this section, the Baud rate is 2,400 Baud. Each Baudcontains four bits (at 9,600 bps), five bits (at 12,000 bps), or six bits (at 14,400 bps). Theredundant bit is not included as part of the Baud.



V.8/V.34: Adaptive Bandwidth

OverviewITU-T introduced the following recommendations for facsimile communication at higher speeds.

• V.8 (1994): Procedures for starting sessions.• V.34 (1994): Specifications for modulation and protocol for modems operating at up to 28,800

bps (modified in 1996 to allow data rates of up to 33,600 bps)

V.34 introduces a lot more technical changes compared with the previous speed upgrade fromV.29 to V.17.Signals used in V.34 procedures include tone signals, and data signals at 300 bps, 600 bps,1200 bps, and from 2.4 kbps to 33.6 kbps.

• T.30 (1996): This recommendation has been modified to include changes to protocol signalingas a result of V.8 procedure implementation (see ‘Protocol – V.8/V.34 Protocol’ for details).

The ‘Protocol – V.8/V.34’ section contains more information on V.8/V.34 modulation, with anemphasis on protocol.



Principal Characteristics

The principal characteristics of V.34 procedure are as follows:

1. The use of Error Correction Mode (ECM) is mandatory.

2. Facsimile machines with a V.34 modem must support V.8. If a communication is not startedwith V.8 procedures, V.34 protocol cannot be used.

3. If V.34 is selected for communication between two terminals, V.17, V.29, V.27ter are notapplied.

For best results, good line condition is required. Transmission time can be halved in thesecases.

BandwidthThe theoretical maximum data rate for a telephone line of bandwidth 3000 Hz and S/N ratio ofabout 30 dB is about 30 kbps.For 26.4 kbps, a bandwidth of 3000 Hz is required.For 28.8 kbps, a bandwidth of 3200 Hz is required.For 33.6 kbps, a bandwidth of 3429 Hz is required.As we can see from this, V.8/V.34 modulation approaches the limits of what is possible on aconventional telephone line, and the highest data rates may only rarely be observed in the field.



Noise Level

The bandwidth required for a certain data speed depends on signal-to-noise ratio (S/N)

For 28.8 kbps, the signal-to-noise (S/N) ratio must be 32-34 dB or better.

Summary of V.8/V.34 TechnologiesThe following is a list of the technologies used to implement V.8/V.34. This section will explainthem in outline.

• V.8 Handshaking• Line Probing• Precoding• Pre-emphasis• Power Control• Trellis Coding

V.8 HandshakingV.8 handshaking is the first thing that happens in a V.8/V.34 communication. This procedureuses 300 bps V.21 signaling to establish whether the other party is V.8/V.34 compatible. If theother end is not compatible, then communication can drop back to a slower modem type, suchas V.27ter.

Line ProbingThe receiver sends out a complex series of signals to analyze the condition of the telephone line.The results of this process determine what the carrier frequency will be for the communication,



the bandwidth that is available (and thus the possible range of data speeds that can be used),and the pre-emphasis and power control parameters.

Line probing is done at the start of every communication, and whenever retraining has to bedone during a communication.

Pre-codingV.8/V.34 modulation approaches the theoretical data capacity limit for a telephone line.Therefore, an adaptation of the most effective receiver equalization technique for analog voicegrade modems is used. This technique is known as Decisions Feedback Equalization (DFE).

However, this technique does not always work well with Trellis Coding. To get around this, thereceiving terminal calculates the best equalizer parameters in the usual way, but sends themback to the sending terminal. The sending terminal then equalizes the signal beforetransmission, and can employ Trellis Coding on this signal without any problem.

The term ‘pre-coding’ refers to something that is done before Trellis Coding.

Pre-emphasisPre-emphasis corrects the signal for distortion by boosting signals in some parts of thewaveband and attenuating others. The frequencies boosted and attenuated depend on theresults of line probing.



Power ControlHigh transmitting power leads to a good S/N ratio at the receiving end but can cause echoeffects. Power control selects the best transmitting power based on the results of line probing, toattain the best possible receiving side S/N with minimal echoes.



Trellis CodingTrellis coding was introduced in V.17/V.32 modulation. V.34 uses a more complex form, knownas ‘four-dimensional’ trellis coding. (V.17 used ‘two-dimensional’ trellis coding.)

The signal constellation contains many more points than the ones for V.17/V.32, but the principleis similar.

However, the signal constellation is intentionally warped to counter non-linear distortion (alsoknown as harmonic distortion), which can cause a lot of problems with high-speed datacommunications, where the difference in phase and amplitude between different points in thesignal constellation is quite small. The warping technique increases the distance between thepoints in the outer margins of the constellation (where the effects of non-linear distortion are thegreatest), but brings those near the center closer together.


Group 3 Fax Communication Protocol

Protocol

Introduction

People often find it hard to relate to each other and exchange information without some kind offormal introduction. Fax machines have similar problems.

Standard signalling procedures for fax machines have been developed so that any pair of faxmachines can communicate with each other, regardless of their makers or countries of origin.

Facsimile machine protocol allows handshaking between the two machines before and after datatransmission. Handshaking allows the machines to exchange identification and information onwhat features they are equipped with. Also, the protocol allows the machines to determine theoptimum transmission speed for the communication.

The most commonly used signalling procedure is known as ITU-T Group 3.

Protocol. This protocol was developed by the ITU-T (International Telecommunications Union –Telecom) and implemented in 1980.

The ITU-T was previously known as the CCITT (Consultative Committee for InternationalTelephony and Telegraphy).



ITU-T Protocol Categories

There are four types of facsimile protocol.

Group 1 (also known as G1)This was implemented in 1972. It allows analog fax machines to send a letter-size or A4 page inabout 6 minutes, with an optional 4-minute transmission speed. Group 1 transmits data usingfrequency modulation (FM). Group 1 protocol does not allow handshaking.

Group 2 (also known as G2)This was implemented in 1976. It allows analog fax machines to send a letter-size or A4 page inabout 3 minutes, with an optional 2-minute transmission speed. Group 2 transmits data usingamplitude modulation (AM), frequency modulation (FM), and vestigial sideband modulation(VSB).

Group 3 (also known as G3)This was implemented in 1980, and is the most commonly used mode of facsimilecommunication world-wide. It allows digital fax machines to send a letter-size or A4 page inabout 30 seconds to 1 minute. Group 3 transmits data using phase modulation (PM), frequencyshift keying (FSK), quadrature amplitude modulation (QAM), and trellis code modulation (TCM).The Group 3 signals have a digital structure, so that information such as machine type andcapabilities can be exchanged during the handshaking procedure.



Basic Group 3 uses V.21/V.27ter/V.29 modem standards to communicate at 9,600, 7,200,4,800, and 2,400 bps. V.17/V.33 modem standards allow speeds of 12,000 and 14,400 bps. Inaddition, V.8/V.34 standards allow speeds up to 33,600 bps.

Group 4 (also known as G4)This was implemented in 1984. It allows digital fax machines to send a letter-size or A4 page inabout 3 seconds. Group 4 was designed for use on high-speed data networks and ISDNs,allowing data communication at high speeds such as 56 kbps or 64 kbps.

This manual will outline the Group 3 protocol system. For full details of ITU-T Group 3 protocolsignalling, refer to the following ITU-T recommendations.

• T.30: Describes the various protocol signals, and their uses.

• T.35: Provides ITU-T member codes for various countries so that they can implement non-standard features.

This section will first describe the basic T.30 G3 protocol at speeds of up to 14,400 bps, withoutECM. Examples of use will be given, showing how fax features such as Polling are implemented.

Error Correction Mode (ECM) will then be described)

After that, the modifications to T.30 that allow high speeds of up to 33,600 bps using V.8/V.34will be described.



Standard Group 3 Protocol (Without ECM)

Phases A to EThe ITU-T T.30 recommendation dividesfacsimile communication into five phases.

Phase A: Call setup

This phase is from the start of the call untilthe fax machines have connected to thetelephone line.

Phase B: Pre-message procedure

During this phase, the two machines exchange information on their capabilities, the transmissionparameters selected for this communication, and confirmation of the parameters that bothmachines can accept.

Modem training also takes place during Phase B.

In addition, the use of optional features and non-standard features can be informed to the otherend during Phase B.

Proto-1.wmf



Phase C: Data communication

This phase is divided into two parts. Signals from each of these parts are transmitted duringPhase C.

• Phase C1: In-message procedure. This controls in-message signalling techniques, such asmessage synchronization and error detection.

• Phase C2: Message transmission. This controls the exchange of data.

Phase D: Post-message procedure

Signalling during this phase informs whether the data was received correctly, and whether or notthere are more pages to follow.

Phase E: Call release

This phase ends when both machines have released the line.


Group 3 Fax Comm

This five-phase debelow. However, nstraightforward. Fophase B or C after

9 August 2003

unication Protocol

scription can be illustrated best by a simple one-page transmission, as shownote that in more complex communications, the situation is not sor example, between pages of a transmission, the procedure will go back to phase D.

Proto 2 wmfPage 649


An Example CommunicationIn this section, we shall examine the G3 protocolprocedure and introduce some of the signals by lookingat a single-page transmission using Group 3 standardprotocol.

Step 1

The transmitting machine (TX) dials the other party.This happens either after the user has pressed Start(automatic dialling) or dialled the other party on anexternal handset (manual dialling). When the receivingmachine (RX) has detected the incoming call, itconnects itself to the line.

Step 2

If the TX side is an automatic dialling fax machine, itwill send out a 1100 Hz signal called CNG after dialling.CNG informs the receiver that a fax machine is calling.The tone has a cadence; it is on for 0.5 s and off for 3s. CNG will be transmitted intermittently until themachine at the other end returns a signal.

About 1.8 s after connecting to the line, the RX sidesends out a 2100 Hz tone to the TX side. This is theCED tone; it informs the TX side that they have

TX RX

'Start' key pressed

Dialling

CNGCED

Connects to the line

1.8s

75ms

0.2s - 3s

75ms

Modemtraining

TCF

0.2s - 3s

CFR0.2s - 6s

Retraining

Onepageof facsimiledata

75ms

0.2s - 3s

0.2s - 6s

EOP

MCF

DCN

DISCSI

DCSTSI

End

V.21modem(300bps)

V.27ter or V.29modem(e.g., at 9,600bps)

RTC

Step 1Step 2

Step 3

Step 4

Step 5

Step 6Step 7

Step 8

Step 9

Step 10



connected to a fax machine. The CED tone lasts for 2.4 to 4.6 s.If the TX side is a manualdialler, the operator at the TX side will press the Start key and hang up the handset upon hearingCED, which is a continuous high-pitched tone.

Step 3

After CED, the RX side pauses for 75 ms. Then it transmits two signals: DIS and CSI. Note thatCSI is not a compulsory signal; some makers may not implement this signal in their products.

DIS contains information about the RX side's capabilities, such as the types of modem installed,the maximum resolution, the printer paper width, and the data compression/reconstructionmethods available. CSI contains the telephone number of the RX side, to identify itself to theoperator at the TX side.

The information in the DIS, CSI, and other protocol signals is digitally coded at 300 bps using atype of frequency modulation known as FSK; a '0' is represented by 1,850 Hz, and a '1' isrepresented by 1,650 Hz.

Step 4

After about 200 ms, the TX side sends out DCS and TSI (TSI is not a compulsory signal). DCSinforms the RX side of how the TX side is set up; it includes the resolution that will be used tosend the message, the document width, the starting modem rate for facsimile data transmission,and the compression method that will be used. TSI contains the telephone number of thetransmitting side, for identification purposes.



Step 5

After about 75 ms, the TX side begins modem training, to check that the V.27ter and V.29modems in both machines are functioning normally; this training check prevents data from beingsent out through a defective modem, which would cause the data to be garbled. Modem trainingstarts at the maximum modem rate (normally 9,600 bps).

During modem training, the TX side modem first transmits a standard test pattern to the RX sideto synchronize the modems (the standard patterns are described in V.27ter for 2,400/4,800 bpstraining and V.29 for 7,200/9,600 bps training). The RX side's modem must be able to detect thestandard pattern correctly from the received signal. Then the TX side modem sends a signalcalled TCF. TCF is a string of zeros lasting for up to 1.5 s. The RX side monitors 0.9 s of thissignal, and checks if any of the zeros have been changed to ones.

Step 6

After about 0.3 s, the RX side replies with the result of the modem training. If training wassuccessful, the RX side sends a CFR signal. If training was unsuccessful (too many errors due toa malfunctioning modem or a noisy telephone line), the RX side sends an FTT signal. Theprocedure then resumes from step 4, at a lower data rate. If training fails at the lowest data rate(2,400 bps), the line is disconnected as fax communication is impossible. When CFR has beensent, the CSI is displayed on the TX side's machine, and the TSI is displayed on the RX side'smachine.

Note: Most machines have a pair of bit switch settings to specify how many bit errors areacceptable in the TCF signal (this setting is known as the training error tolerance).



Step 7

After about 0.2 s, the TX side is ready to send facsimile data. First, a short modem trainingpattern is sent to confirm modem synchronization (this signal is known as retraining). Then thefacsimile data is sent at the modem rate for which modem training was successful.

At the end of the data, an RTC code is sent. This consists of six consecutive EOL(000000000001) codes. RTC informs the other end that the page of data has ended. (For moreabout EOL codes, refer to "Compression Techniques".)

Step 8

After transmitting the end of the page of data, the TX side pauses for about 75 ms. Then the TXside sends a post message command to the RX side, to inform it of what is going to happennext. In our example, there are no more pages, so the TX side sends an EOP signal. In othersituations, the TX side might send MPS (indicating that there is another page to come, and it willbe transmitted using the same settings as the previous page; the next page is sent from step 7)or EOM (indicating that there is another page to come, but it will be transmitted using differentsettings from the previous page; the procedure goes back to step 3).

Step 9

After about 0.2 s, the RX side sends back a post-message response, to inform whether the pagewas received correctly or not. If the page was received correctly, the RX side sends out MCF. Ifthe page was not received correctly, the RX side sends out RTN; an alarm sounds at the TX sideand an error report may be printed.



Step 10

After about 0.2 ms, the TX side sends a DCN signal to inform the RX side that it is going todisconnect from the telephone line. Both machines then return to standby mode. Thecommunication is over.

Notes:

• 75 ms interval - This interval is required whenever the machine has to switch between signalsfrom the V.21 to the V.27ter/V.29 modems (or vice versa).

• 0.2 - 3 s interval - This interval occurs whenever communication is handed over to the otherterminal in expectation of a command from the other end. If the terminal does not receive acommand within 3 s (the value of the ITU-T T4 timer), it will resend the signal. However, afterDIS/CSI or after EOP, if a reply is still not received at the third try, the machine will send DCNand a Line Fail will be detected.

• 0.2 - 6 s interval - This interval occurs whenever communication is handed over to the otherterminal in expectation of a response to a command. If the terminal does not get a responsewithin 6 s (the value of the ITU-T T2 timer), it will send DCN and a Line Fail will be detected.



Non-Standard Group 3 Protocol

Standard Group 3 protocol provides the framework for Grofew features such as Free Polling. However, some manufafeatures consider that ITU-T standard Group 3 protocol is lmanufacturers have used optional signals provided by the their own additional features, such as Transfer Request anthese features only work between fax machines thatwere produced by the same maker.

The use of these optional signals is illustrated in theprotocol sequence on the right, which is for a single-page transmission.

The rest of the transmission (after TCF) is the same asfor standard Group 3 protocol as shown in the previoussection.

The new signals are as follows.

NSF: This informs the transmitting side of who themanufacturer is, and what non-standard features areavailable.

NSS: This informs the receiving side of what non-standard features will be used for the transmission. Ifthe maker of the TX side is different from that of the RX

'

9 August 2003

Protocol

up 3 facsimile communication, and acturers who wish to introduce newimited. Therefore, theseT.30 recommendation to implementd Confidential Transmission. Usually,

TX RX

Start' key pressed

Dialling

CNGCED

Connects to the line

1.8s

75ms

0.2s - 3s

75ms

Modemtraining

TCF

NSS

NSFCSIDIS

Proto-4.wmf

Page 655


side, NSS will not be sent. DCS and TSI will be sent, and standard Group 3 protocol will befollowed.

Note: NSF is divided into two parts: NSF(S) first, then NSF(C). NSF(S) contains information onthe machine's non-standard capabilities, and NSF(C) contains the RTI, which is an alternative tothe CSI as a means of identification. Similarly, NSS is also divided into NSS(S) and NSS(C).



Protocol Signals

HDLC FramesProtocol signals such as CED and CNG are just single tones transmitted for a certain period oftime; these have no structure. However, signals that consist of digital information, such as DIS,NSF, and so on, have a frame-like structure known as HDLC (High-level Data Link Control).

The basic HDLC frame structure consists of a number of frames, each of which is subdividedinto a number of fields. An example is shown below, in which a block of four protocol frames(NSF(S), NSF(C), CSI, and DIS) is transmitted in sequence.

Proto-5.wmf



Each of the fields is described below.

Preamble

A preamble will be sent before any digitally coded signal if the direction of communication hasjust changed. The preamble assures that all elements of the communication circuit, such asecho suppressors, are properly conditioned so that the following data can be passed withoutbeing damaged. The preamble consists of a sequence of flags transmitted for about 1 s.

Flag: Code 01111110

Flags show the start and end of each frame, and establish bit and frame synchronization.

Address Field (AF): Code 11111111

This is intended to provide station identification in a multi-point network. For communication overthe public telephone network, the address field is fixed at 11111111.

Control Field (CF): Code 1100X000

If another signal immediately follows this one, X is 0. If this is the last signal, and a response isexpected from the other end, X is 1.

Facsimile Control Field (FCF)

This eight bit code identifies the protocol signal. There is information on all the Group 3 protocolsignals later in this section.



Facsimile Information Field (FIF)

This field has bit assignments to show the settings of various features, such as resolution. Thisfield is used in NSF, CSI, DIS, NSC, CIG, DTC, NSS, DCS, and TSI frames, and some of theECM protocol signals. The bit assignments for some signals are given in the ITU-T T.30recommendation. Assignments for NSF, NSS, and NSC will vary from maker to maker, and areconfidential.

Cyclic Redundancy Check (CRC)

This is also known as the Frame Check Field. This is a 16-bit checksum based on the contentsof the AF, CF, FCF, and FIF fields. When receiving a frame, the receiver makes an identicalchecksum calculation based on the received data and checks the result with the received CRCcode to determine whether there have been any errors. The method of calculating the CRC codeis given in ITU-T recommendation T.30.



Table of Group 3 Protocol SignalsThe following table shows all the Group 3 protocol signals and a brief description of what theydo. Some examples will be shown in the following section. This section covers only the basicGroup 3 signals; ECM signals are described later.

Stage: At the start of reception

Name Full Name FCF Code UseCED Called Station

IdentificationNone The machine is ready to receive. CED is a 2100

Hz single frequency signal.DIS Digital Information

Signal0000 0001 DIS informs the TX side of the RX side's

capabilities (modem type, I/O rate, printer paperwidth, and so on).

NSF Non-standard Facilities 0000 0100 NSF is an optional signal. It informs the TX side ofany features that the RX side's has that are notITU-T standard (for example, confidentialcommunication, transfer request).

CSI Called StationIdentification

0000 0010 This contains the RX side's tel. number to identifyitself to the TX side's operator.



Stage: At the start of transmission

Name Full Name FCF Code UseCNG Calling Tone None The machine is ready to transmit. CNG is an 1100

Hz tone with the following cadence: on for 0.5 sand off for 3 s.

DCS Digital CommandSignal

X100 0001 DCS tells the RX side what settings will be used totransmit the fax message (such items as modemrate resolution and document width are included).

NSS Non-standard FacilitiesSet-up

X100 0100 NSS is an optional signal. It informs the RX side ofany non-standard features that the TX side will beusing for the transmission.

TSI Transmitting StationIdentification

X100 0010 This contains the TX side's tel. number to identifyitself to the RX side operator.

Stage: During polling reception

Name Full Name FCF Code UseDTC Digital Transmit

Command1000 0001 Informs the called machine of the calling machine's

capabilities and requests polling reception.NSC Non-standard

Facilities Command1000 0100 The same as DTC except that it informs non-

standard features.CIG Calling Station

Identification1000 0010 This contains the calling side's telephone number

to identify itself to the called side's operator.



Stage: During modem training

Name Full Name FCF Code UseModem training None The TX side sends a standard test pattern to

check whether both modems are functioningproperly. The test pattern is described in ITU-Trecommendations V.27ter and V.29.

TCF Training Check Field None This modem training signal is a series of zeroslasting for 1.5 s. It is not a HDLC frame.

CFR Confirmation toReceive

X010 0001 This informs the TX side that modem training wassuccessful.

FTT Failure to Train X010 0010 This informs the TX side that modem training wasnot successful.

Stage: After transmitting a page of data

Name Full Name FCF Code UseEOP End of Procedure X111 0100 This informs the RX side that there are no more

pages to send.EOM End of Message X111 0001 This informs the RX side that the settings for the

next page (resolution, for example), will bedifferent from those for the page that was just sent.

MPS Multi Page Signal X111 0010 This informs the RX side that the settings for thenext page will be the same as for the page thatwas just sent.



Stage: When making a voice request

Name Full Name FCF Code UsePRI-EOP

Procedure Interrupt -End of Procedure

X111 1100 This is the same as EOP, except that it indicatesthat a voice request has been made.

PRI-EOM

Procedure Interrupt -End of Message

X111 1001 This is the same as EOM, except that it indicatesthat a voice request has been made.

PRI-MPS

Procedure Interrupt -Multi Page Signal

X111 1010 This is the same as MPS, except that itindicates that a voice request has been made.

Stage: Response after receiving a page of data

Name Full Name FCF Code UseMCF Message Confirmation X011 0001 This informs the TX side that the page of data and

the post-message command were receivedcorrectly.

RTP Retrain Positive X011 0011 This informs the TX side that the page of data wasreceived correctly, but that additional pages canonly be sent after NSS/DCS and training.

RTN Retrain Negative X011 0010 This informs the TX side that the page of data wasnot received correctly.

PIP Procedural InterruptPositive

X011 0101 This informs the TX side that the page of data wasreceived correctly, but further transmission is notpossible without the presence of the operator.

PIN Procedural InterruptNegative

X011 0100 This informs the TX side that the page of data wasnot received correctly, and that the operator'spresence is required.



Stage: At any time, whenever necessary

Name Full Name FCF Code UseCRP Command Repeat X101 1000 This requests retransmission of the previous

signal.DCN Disconnect X101 1111 This informs that the machine is about to release

the line.

Notes: • In the FCF code, X is 1 on the side that received DIS or NSF.

• The FCF as indicated in this table is transmitted from the left side first.

• Like NSF and NSS, NSC consists of two parts: NSC(S) and NSC(C).

• If more pages follow after a voice request, the protocol resumes from CED thenNSF/DIS after the conversation.



Comparison of Standard and Non-standard Group 3 Signals

Capability information IdentifierRX side TX side Polling rx

requesterRX side TX side Polling rx

requesterNon-std NSF(S) NSS(S) NSC(S) NSF(C) NSS(C) NSC(C)Standard DIS DCS DTC CSI TSI CIG

The identifier in standard mode is the data programmed into the CSI. In non-standard mode, it isthe data programmed into the RTI.



ITU-T Timers

ITU-T T1 Time

Just after transmitting side finishes dialling the other end, T1 time starts and the machine waitsfor a signal, such as identification (NSF/DIS/CSI), from the receiving end. If the T1 time runs outbefore a response is detected, the machine disconnects the line.

For the receiving side, T1 starts when it has sent out NSF/DIS/CSI, and is waiting for aresponse. While waiting, the machine retransmits NSF/DIS/CSI.

The ITU-T standard value of the T1 timer is 35 s ± 5 s.

ITU-T T2 Time

After sending a response to training (CFR or FTT) or a response to a received page (such asMCF), the T2 timer starts. If T2 runs out before image data or a command signal is received, themachine disconnects the line. The ITU-T standard value of T2 is 6 s ± 1 s.

ITU-T T3 Time

T3 starts when the machine calls the operator (after it has detected PIN, PIP, or PRI-Q; e.g., theother side made a voice request). If the operator does not answer within T3, the machine willcontinue with the facsimile communication procedure that was interrupted. The value of the T3timer is 10 s ± 5 s.



ITU-T T4 Time

T4 starts when a machine sends out a command (such as NSF/DIS/CSI, TCF, or EOP). If thetransmitting terminal does not receive a reply within T4, it will resend the signal. However, ifwaiting for a response to NSF/DIS/CSI or EOP/EOM/MPS, it will disconnect the line if a reply hasnot been received after the signal has been sent out three times. The values of the T4 timer areas follows:

• Automatic receiving fax machines: 3.0 s ± 15%

• Manual receiving fax machines: 4.5 s ± 15%

ITU-T T5 Time

This is used with ECM. The transmitting terminal starts T5 when it detects the first RNR andresets it when it detects MCF or ERR. If T5 runs out before MCF or ERR are detected, thetransmitter sends DCN. Examples are shown later in this section. The value of the T5 timer is 60s ± 5 s.



Example Uses Of Group 3 Protocol Signall

Two-page TransmissionThe left side of the diagram shows whathappens when the second page is transmittedwith the same settings as the first page.However, the right side of the diagram showswhat happens if the transmitter's operatorchanges the settings for the second page, forexample, by selecting a different resolution.The diagrams begin half-way through the firstpage. Until that point, the protocol is the sameas for one-page transmission.

9 August 2003

Protocol

ing TX RX

Retraining

EOP

MCF

DCN

End

Facsimile data -Page1

MPS

MCF

Facsimile data -Last page

TX RX

Facsimile data -Page 1

EOM

MCF

CFR

Modemtraining

TCF

NSS/DCS

Retraining

EOP

MCF

DCN

End

Facsimile data -Last page

NSF/DIS

6 s

Proto-6.wmf

Page 668


Automatic FallbackThe diagram shows how automatic fallback is achieved.Automatic fallback occurs if modem training cannot be donesuccessfully, and the transmitter has to use a slower modemrate. In the example shown, training fails at 9,600 and 7,200bps, but succeeds at 4,800 bps. The protocol is only shown upto the transmission of facsimile data.

9 August 2003

Protocol

TX RX

CED

Modemtraining

TCF

FTT

DISCSI

(9,600 bps)

Modemtraining

TCF

CFR(4,800 bps)

Modemtraining

TCF

FTT(7,200 bps)

DCSTSI

DCSTSI

DCSTSI

Retraining

One pageof facsimiledata

(4,800 bps)

NSS

NSF

Proto-7 wmf

Page 669


PollingThe diagram shows how polling is done.

• Polling will only work if:

• Both terminals have compatible polling features.

• The ID codes are the same, unless free pollinghas been selected. (Free polling is a ITU-Tstandard procedure, using DIS, DTC, CIG, andDCS. However, polling using ID codes is non-standard, using NSF, NSS, and NSC, and canonly be guaranteed between models produced bythe same maker.)

• The polled side is ready for polling (it must have adocument ready on polling standby).

Note how the direction of the communication changesafter the polling side has sent out NSC or CIG/DTC.

Polling side

CED

Modemtraining

TCF

Retraining

Polled side

NSF/CSI/DIS

NSC/CIG/DTC

Fax messagedata

NSS

EOP

CFR

MCF

DCN

Proto-8.wmf



Voice RequestThe following diagrams showhow the transmitting sidemakes a voice request to thereceiving side.

Voice request does not workwhen the other end does nothave the voice requestfunction.

PRI-Q refers to PRI-EOM,PRI-EOP, or PRI-MPS,whichever is applicable in thecircumstances.

PIP/PIN means either PIP orPIN.

The diagrams are for ITU-Tstandard procedure. In non-standard procedure, PRI-Q issent up to 6 times. If there isstill no response, Q is sent.

TX RX

Faxmessagedata

"VoiceRequest"key pressed

PRI-Q

PRI-Q

3s "Stop" keypressed

PIP/PIN

Operator calltone ringing

PRI-Q

Operator call tonerings for 2s

"Stop" keypressed

Conversation

CED

NSS/DCS

NSF/DIS

The receiver operatorresponds to the voice request.

Proto-9.wmf

TX RX

Fax messagedata

"Voice Request"key pressed

PRI-Q

PRI-Q


PRI-Q

MCF/RTN/RTP

for 10 s

Fax communication continues

TX RX

Last page

"Voice Request"key pressed

PRI-EOP

PRI-EOP


PRI-EOP

MCF/RTN/RTP

for 10 s

DCN

The receiver operator does notrespond to the voice request.

Proto-10.wmf9 August 2003 Page 671

"ui

9 A


Commonly Occurring Problems- When the page is not received correctly -

TX RX

MPS

RTN

Fax messagedata

NSS/DCS

Modemtraining

TCF

Retraining

CFR(FTT)

LineFail" blinksntil theStopkey

s pressed.

Nextpage

Using MPS

Proto-11.wmf

TX RX

EOP

RTN

Fax messagedata

DCN

"Line Fail" blinksuntil the Stop keyis pressed.

Using EOP

Proto-12.wmf

TX RX

EOM

RTN

Fax messagedata

NSS/DCS

Modemtraining

TCF

Retraining

CFR(FTT)

"Line Fail" blinksuntil the Stop keyis pressed.

NSF/DIS

6 s

Nextpage

Using EOM

Proto-13.wmf

ugust 2003 Page 672


RTN may make older terminals release the line. Newer models continue as shown, even though"Line Fail" blinks. For example, if page 3 in a five-page transmission fails, the machine willcontinue to send pages 4 and 5. The fact that page 3 failed will be output on an error report.

If the transmitting machine is using memory transmission (without ECM), and a page fails, thesame page will be retransmitted using the above protocol procedure (or using EOP or EOM ifrequired).



- When there is a copy jam or paper runs out during reception -

TX RX

MPS/EOM

PIN

Fax messagedata

NSS/DCS

Modemtraining

TCF

DCN

"LineFail" blinksuntil theStopkeyis pressed.

6s max.

Copy jamoccurs

FlagOperator callrings for upto22s.

Using MPS or EOM

Proto-14.wmf

TX RX

EOP

PIN

Fax messagedata

DCN"LineFail" blinksuntil the Stop keyis pressed.

6s max.

Copy jamoccurs

FlagOperator callrings for upto 22 s.

Using EOP

Proto-15.wmf



If the RX side does not detect MPS/EOM/EOP within 6 s of the jam occurring, it will disconnectthe line.

The operator call rings for 22 s in non-standard mode, but only for 10 s in ITU-T standard Group3 mode.

The diagrams on the previous page show what happens when the receiving machine has nomemory. If the receiving machine does have SAF memory, the incoming data can be stored inthat memory using a process known as Substitute Reception. This is explained on the nextpage.



Substitute ReceptionThere are two procedures for substitutereception. Some models have a bit switchsetting to select one or the other of these.Both procedures are shown.

In the left-hand procedure, data is stored inmemory as it comes in. So, if the printer hasa problem, the data is already saved, andany more incoming pages are automaticallysaved to memory.

In the right-hand procedure, the data is notstored during reception. If a problem occurs,the receiver sends out PIN and thecommunication stops; the last page of thecommunication is lost. Substitute receptiononly takes place from the nextcommunication.

The operator call rings for 22 s in non-standard mode, but only for 10 s in ITU-Tstandard Group 3 mode.

TX RX

Retraining

EOP

MCF

DCN

End

Facsimiledata -Page2

MPS

MCF

Facsimiledata -Last page

TX RX

Facsimiledata -Page2

EOM

PIN

DCN

NSS/DCS

CED

Jam Jam

Operator callrings for upto22s.

Flag

Line isdisconnected

NSF/DIS

Modemtrn.

TCF

Proto-16.wmf



AI Short Protocol

Overview

AI (Artificial Intelligence) Short Protocol reduces the time required for the protocol exchange betweenterminals. When the machine communicates with a particular fax terminal for the first time, protocolproceeds as normal. However, the communication parameters agreed during the protocol exchangeare stored, and so is the modem rate that was used for sending the last page of the message. Then,when the same number is called again some time later, these parameters are immediately put intoeffect, eliminating most of the handshaking and training procedures.

This feature is only available with numbers that are stored as Quick or Speed Dials.

Notes: This feature may not be effective for international communication because of the linedelay caused by satellite links. The delay means that the rx side may not be able toreceive the AI Short Protocol trigger signal (800 Hz) before it has finished sending CED.



Basic Protocol Procedures

- First Communication - - Later

Communications -

1. After it detects CED, the tx side will send out an 800 Hz signal for 0.5 s. Then, it will sendNSS(A) and NSS(C). If the RTI is not programmed, NSS(C) will not be sent.

Tx Rx

CED

NSF(S)/NSF(C)

CSI/DIS

NSS(S)/NSS(C)

TCF

CFR

ImageData

Aipro1.wmf

Tx Rx

CED

NSS(A)/NSS(C)

CFR

ImageData

800 Hz

0.5s

0.2s0.2s

75 +/- 15ms

Aipro2.wmf



2. When it detects 800 Hz, the rx side enters AI Short Protocol mode. It will stop sending CED0.2 s after it detects the 800 Hz signal, and it will not send out NSF or DIS.

3. If the CRC data in the rx side's own NSF(S) signal is the same as that of the received NSS(A)signal, the rx side will send CFR.If the CRC is different, the rx side will send FTT and NSF. Then normal G3 protocol resumeswith NSS(S). In this case, the overall communication time will be longer.

4. After receiving CFR, the tx side will send image data at the modem rate determined by the AIShort Protocol Algorithm (see below).



Communication Using AI Short Protocol

- First Recording -

The machine recognizes it as a first communication if the AI Short Protocol data for thatQuick/Speed Dial contains no NSF(S) or RTI/CSI information.

Data is recorded for use with AI Short Protocol if:

• The number is a Quick or Speed Dial

• The remote terminal has the AI Short Protocol feature (bits 1, 2, and 3 of NSF(S) must beon)

• NSF(S) was received correctly, even if the protocol failed elsewhere

In the first communication, data will not be recorded if a closed network transmission failed dueto an ID Code mismatch.

AI Short Protocol data can be recorded for any transmission mode (such as multi-pagetransmission, transfer request, and so on).

During communication, the following takes place:

• Any modem rate data in the AI Short Protocol memory for that Quick/Speed Dial is deleted

• The CRC data of the received NSF(S) is stored



• The modem rate for the final page is stored

- Later Communications –

AI Short Protocol takes place if:

• The remote terminal's number is stored as a Quick or Speed Dial

• AI Short Protocol data exists for that number

• A 2100 Hz signal (CED) is received<R>

AI Short Protocol data is deleted from the memory if:

• The machine at the other end has been replaced with a machine that does not have AIShort Protocol (if NSF indicates the absence of this feature, or if DIS is received)

• If the Quick/Speed Dial is reprogrammed

AI Short Protocol data is replaced if:

• The response to NSS(A) is NSF/DIS

• Multipage transmission, voice request, page retransmission



NSS(A) Frame FormatHDLC FIF

Flag AF CF FCF ITU-TCode

MakerCode

P. ID IDCode

NSS(A) FCS Flag

• Protocol ID (P. ID) for NSS(A) = 04[H]

• ID Code = ID Code for Polling, Transfer Request, and so on

• NSS(A): CRC data and feature information (see below)

NSS(A) Frame Bit Assignment

Bits Contents1-8 Contents of CRC in other terminal's NSF(S): Low byte9-16 Contents of CRC in other terminal's NSF(S): High byte

17-40 Facsimile feature information

At the receiving terminal, the CRC data in the received NSS(A) signal is compared with the CRCdata of its own NSF(S) signal.

• If these are the same, the receiving machine prepares to receive, without sending outNSF(S).

• If these are not the same, the receiving machine will send out FTT then NSF(S). At thetransmitting side, the AI Short Protocol data for this machine will be replaced.



AI Short Protocol AlgorithmNotes: 1. This depends on a RAM

address or dedicatedtransmission parametersetting. If line conditionsare not constant, TCFshould be added afterNSS(A).

2. First Communication: Ifthe communication failsdue to third try fail ormodem rate fallbackfailure, no modem ratehistory is stored for thatnumber. However, inlater communications,800 Hz will be sent,because the NSF(S) andRTI/CSI data arepresent.



Tx Rx

CED

800 Hz

NSS(A)

FTT

TCF 9600 bps

NSS(A)

Retraining 7200 bps

CFR

ImageData

Tx Rx

CED

800 Hz

NSS(A)

Retraining 9600 bps

CFR

ImageData

Type 1 Type 2

Aipro3.wmf



Short PreambleIf both communicating machines have the Short Preamble feature, the time required by theprotocol procedure can be reduced, as explained below.

• In standard Group 3 protocol, there is a one-second preamble at the start of each signal orgroup of signals (see section 5 "Protocol Signals"). If Short Preamble is used, this isreduced to 0.2 second.

• Normally there is a minimum 0.2 pause in the signalling whenever communication ishanded over to the other terminal (see section 3 "Standard Group 3 Protocol"). If ShortPreamble is used, the minimum becomes 0.1 s.

As a result, about 4 seconds can be shaved off the protocol time during a one-pagetransmission.



Secure TransmissionWith Secure Transmission, the data isscrambled before transmission. The twocommunicating machines check whether theSecure IDs are the same, and whether themachine can do Secure Transmission orSecure Reception.

TX RX

CNGCED

Training

TCF

CFR

Retraining

EOP

MCF

DCN

Faxmessage

NSFNSS

NSFNSS

TX RX

CNGCED

NSFDCN

TX RX

CNGCED

NSFNSS

NSFDCN

If the Rx side is notequipped with this feature.

If the Rx side does not havethe same Secure ID as the Tx side.

Proto-17.wmf



Error Correction Mode (ECM)

BackgroundECM is an optional extension to Group 3 Protocol. It was recommended in 1986 as acountermeasure to the frequent data errors that occur in areas that suffer from noisy telephonelines.

Transmitters that have SAF memory are able to resend data without using ECM. However, asthe whole page is resent, the communication takes a lot longer. With ECM, only the damagedparts of the data are resent, so although there is extra protocol overhead, time can be saved inareas where errors are frequent. Also, a large SAF memory is not needed for retransmittingdata, as long as the machine has a small memory set aside for ECM (this is known as the ECMmemory).

Principle

Data Structure

Without ECM, fax message data is sent as a continuous stream of bits, in units of a page.However, in ECM, a HDLC frame structure is used to send fax message data as well, as for theprotocol signals.

ECM works with four units: the octet, the frame, the block, and the page.



Each HDLC frame consists of 256 octets (8-bit groups) of facsimile data (64 octets is anoptional size), and 8 octets for the other parts of the HDLC frame (flags, address field, controlfield, and so on).

If a page of compressed data needs more than 256 frames, the page is divided into<B>blocks<D>. Each of these blocks, also known as "partial pages", consists of 256 HDLCframes. Each new page starts with a new block.

An average compressed page takes up about 320,000 bits. Therefore, assuming a 256-octetframe size, an average page takes up about half a block. If halftone is used, a lot more bits willbe generated, and more than one block may be required for a page.

Procedure

The page is sent in units of one block; each block is a sequence of up to 256 HDLC frames.After receiving the block, the receiver informs whether the block was received with or withouterrors. If there were errors, the receiver informs which HDLC frames contained the errors, andasks the transmitter to resend those frames.



Basic Protocol

The diagram shows the transmission of a one-page faxmessage, with no errors. The page is small enough to fitinto 256 frames (or one block).

The procedure is basically the same as for Group 3without ECM, except for the HDLC frame structure of thefax message data, which will be explained soon, and thenew signal PPS.EOP replacing EOP. The new signalsPPS.EOP, PPS.EOM, PPS.MPS, and PPS.PRI-Q areequivalent to EOP, EOM, MPS, and PRI-Q as used inGroup 3 protocol without ECM (see the previous pages).

If the page requires more than 256 data frames and mustbe divided into more than one block, a signal calledPPS.NULL is used instead.

TX RX

'Start' key pressed

Dialling

CNGCED

Connects to the lin

Modemtraining

TCF

CFR

Retraining

PPS.EOP

MCF

DCN

DISCSI

DCSTSI

End

Faxmessage

NSF

NSS

Ecm1.wmf



If the receiver detects errors in the data, theprotocol procedure begins to look quitedifferent. This page shows what happens. Inthis example, the errors are corrected at thefirst attempt.

TX RX

CNGCED

Modemtraining

TCF

CFR

Retraining

PPS.EOP

PPR

DISCSI

DCSTSI

End

Faxmessage

DCN

Retraining

Error framesresent

PPS.EOP

MCF

NSS

NSF

Ecm2.wmf



HDLC Data Frame StructureWhen ECM is used, compressed facsimile data is sent in blocks made up of HDLC frames. Thename of the data signal is FCD. The facsimile message data is transmitted in the FacsimileInformation Field (FIF) of this FCD signal.

The following diagram shows the structure of a block of ECM data, and the frames in that block.

Retraining Data RCP

FCDframe 0

FCDframe 1

- - - - - FCDframe255

RCP RCP RCP

Flag AF CF FCD Frameno.

Faxdata

FCS F

FCF FIF

Flag AF CF RCP FCS F

FCF



Three consecutive RCP frames signify the end of a block. After RCP, error correction signallingis done, then error frames are resent or the next block is sent.

The above diagram shows a full block of 256 full data frames. If the final block in a page is onlypartly full, or if the page does not need a full block, zeros are used to fill up the frame where thedata ended. Then the three RCP frames follow. The data structure is as follows.

Retraining Data RTC Zeros RCP

FCDframe 0

FCDframe 1

- - - - - FCDframe N

RCP RCP RCP

Flag AF CF FCD Frameno.

Faxdata

RTC Zeros FCS F

FCF FIF

Denotes the end of image data



ECM Protocol SignalsName Full Name FCF Code UseCTC Continue to Correct X100 1000 The TX side informs the RX side that it

will continue attempting to correct thisblock of data after receiving CTR fromthe RX side.

CTR Response to CTC X010 0011 The RX side acknowledges receipt ofCTC, and states that it is ready toreceive.

EOR End of Retransmission X111 0011 The TX side informs the RX side that itwill not continue attempting to correctthis block of data, and that it will go on tothe next block after receiving ERR fromthe RX side.

ERR Response to EOR X011 1000 The RX side acknowledges receipt ofEOR, and states that it is ready toreceive.

FCD Facsimile Coded Data 0110 0000 The FIF of this signal contains faxmessage data. Up to 256 of theseframes can be sent consecutively as oneblock of data.



Name Full Name FCF Code UsePPS Partial Page Signal X111 1101 This tells the RX side that a block of data

has just been sent. PPS also informs thepage number, block number, and thenumber of frames in the block.

PPR Partial Page Request X011 1101 This informs the TX side that the blockjust received contained errors. It informswhich frames contained the errors andasks for these frames to beretransmitted.

RCP Return to Control forPartial Page

0110 0001 This informs the RX side that there is nomore data in the current block.

RR Receive Ready X111 0110 The TX side asks the RX side whether itis ready to receive data.

RNR Receive Not Ready X011 0111 The RX side informs that it is not readyto receive data, perhaps because theECM memory still holds some data.



Notes: • MCF is only returned when the RX side has received a block without errors, or whenall errors for the block have been corrected.

• MPS, EOM, EOP, and PRI-Q are not used between blocks. Instead, PPS and EORhave an extra Facsimile Control Field to carry a NULL, EOP, EOM, MPS, or PRI-Qsignal. For example, PPS.NULL means that the page has not finished (at least onemore block is needed), and PPS.EOP means that this is the last page of the faxmessage. Refer to the ECM protocol examples in this section to see the usage ofthis type of signal.



Examples of ECM Protocol ProceduresWe have already seen the simplest case.Now let us examine some more complexsituations. NSF and NSS are not shown inthese diagrams.

Error Correction

In this example, page 1 has more than 1block, so PPS.NULL is used after sendingdata. After 4 attempts at 9,600 bps, CTC in-forms the RX side that the next attempt will beat 7,200 bps. This attempt succeedsimmediately. This usage of CTC to indicatefallback varies from maker to maker.

TX RX

CNGCED

ModemtrainingTCF

CFR

RetrainingFaxmessagePage1, block1

PPS.NULL

PPR

RetrainingError frames resent

PPS.NULL

PPR


PPS.NULL

PPR


PPS.NULL

PPR


PPS.NULL

MCF

CTC

CTR

NSFDISCSI

NSS/DCS/TSI

Ecm3.wmf



Page 1 has more than one block, and the firstblock cannot be sent. However, in thisexample, the machine does not use CTC toreduce the modem rate after four failures, andthe TX side states to the next block. Insteadof EOR.NULL, the TX side could sendEOR.MPS and go on to the next page,skipping remaining blocks in page 1completely.

TX RX

CNG

CED

ModemtrainingTCF

CFR

RetrainingFax messagePage 1, block 1

PPS.NULL

PPR


PPS.NULL

PPR


PPS.NULL

PPR


PPS.NULL

PPR

Retraining

PPS.NULL

MCF

EOR.NULL

ERR

Fax messagePage 1, block 2

NSFDISCSI

NSS/DCS/TSI

Ecm4.wmf



In this example, a two-page message is sent.Each page has only one block. Note the useof PPS.MPS and PPS.EOP, which is similarto the use of MPS and EOP in Group 3protocol without ECM.

E

E

E

9 August 2003

Protocol

TX RX

CNGCED

ModemtrainingTCF

CFR

RetrainingFax messagePage 1

PPS.MPS

PPR

Retrainingrror frames resent

PPS.MPS

PPR


PPS.MPS

MCF

PPS.EOP

PPR

MCF



PPS.EOP

DCN

NSFDISCSI

NSS/DCS/TSI

Ecm5.wmf

Page 698


Here, the TX side sends a two-block page. Whilesending PPS.NULL, some noise on the line stopsthe RX side from detecting it. The TX side resendsthe signal if the ITU-T T4 timer expires before areply is detected. The ITU-T timers are explainedlater in this section.

9 August 2003

Protocol

TX RX

CNG

CED

Modemtraining

TCF

CFR

RetrainingFax messagePage 1, block 1

PPS.NULL

PPS.NULL

PPR


PPS.NULL

MCF

Retraining

PPS.EOP

MCF

Fax messagePage 1, block 2

Couldnot bereceivedasa result oflinenoise.T4

DCN

NSFDISCSI

NSS/DCS/TSI

Page 699


In this example, the TX side cannot detect PPRbecause of noise on the line. After T4 elapsedwithout detection anything the previous signal is sentout again.

E

9 August 2003

Protocol

TX RX

CNGCED

ModemtrainingTCF

CFR

RetrainingFax messagePage1, block 1

PPS.NULL

PPS.NULL

PPR


PPS.NULL

MCF

Retraining

PPS.EOP

MCF

Fax messagePage1, block 2

T4

DCN

PPRcannot bereceivedasa result oflinenoise.

PPR

NSS/DCS/TSI

NSFDISCSI

Page 700


In this case, line noise has damaged the data.If the data signal is totally destroyed, the RXside can check the block and page counters tosee which part of the fax message is missing.

9 August 2003

Protocol

TX RX

CNGCED

ModemtrainingTCF

CFR


PPS.NULL

PPS.MPSPPR


PPS.MPS

MCF

MCF


andsoon

Datasignaldamaged bylinenoise

NSS/DCS/TSI

NSFDISCSI

Ecm8.wmf

Page 701


Flow Control

On the transmitting side, data flow is controlled by sending consecutive flags before the firstframe, or between frames as long as the ITU-T T1 timer is not exceeded.

On the receiving side, flow is controlled using the RNR signal, as shown in the followingexamples.



The TX side starts the T5 timer when it first detects RNR.The TX side repeatedly asks the RX side whether it isready to receive, using RR. If T5 runs out before the TXside detects MCR or ERR, the TX side sends DCN.

9 August 2003

Protocol

TX RX

CNG

CED

ModemtrainingTCF

CFR

RetrainingFaxmessagePage1, block 1

PPS.NULL

PPR


PPS.NULL

RNR

MCF

MCF


PPS.EOP

DCN

Memory busy

RR

RNR

RR

T5starts

T5 reset

NSS/DCS/TSI

NSFDISCSI

Page 703


In this example, T5 runs out so the TX side sendsDCN. Also, if the TX side cannot detect any reply toRR comes after three attempts, the TX side will sendDCN.

9 August 2003

Protocol

TX RX

CNGCED

ModemtrainingTCF

CFR


PPS.NULL

MCF

PPS.MPS

RNR

RNR


DCN

Memorybusy

RR

RNR

RR

T5starts

Damagedbylinenoise

RR

T4starts

T4 reset

RNR

RR

T5runsout

NSS/DCS/TSI

NSFDISCSI

Ecm10.wmf

Page 704


Procedural Interrupts

This shows what happens when the TX side operator makes avoice request.

TX RX

CNG

CED

Modemtraining

TCF

CFR


PPS.PRI-EOP

PPR

(Errors)

Retraining

PPS.PRI-EOP

Resend errorframes

PIP

PRI-EOP

Operatoralerted

Operatoralerted

Operatoron-lineOperator

on-line

(Operatorinterventionrequested)

NSS/DCS/TSI

NSFDISCSI

Ecm11.wmf



This shows what happens when the RX sideoperator makes a voice request.

9 August 2003

Protocol

TX RX

CNGCED

ModemtrainingTCF

CFR


PPS.MPS

PPR

(Errors)

Retraining

PPS.MPS

Resend errorframes

PIP

PRI-MPS Operatoralerted

Operatoralerted

Operatoron-line

(Operatorinterventionrequested)

Operatoron-line

PIP

NSS/DCS/TSI

NSFDISCSI

Page 706


Flexible Implementation of ECM Protocol

The ITU-T standard for ECM allows some flexibility, and manufacturers may implement ECM inslightly different ways. The following notes explain how this manufacturer has implementedsome of the more flexible rules.

Frame size

The machines are set up for a frame size of 256 octets.

In receive mode, the machines adopt whichever of the two optional frame sizes (256 or 64) isbeing used by the sender.

Some makers may use non-standard frame size options. This manufacturer's machines cancommunicate with terminals that use non-standard frame sizes lower than 256 octets. However,communication is impossible if the other terminal's non-standard frame size is higher.

Block size

This is always 256 except for the following cases

• A block at the end of a page

• When resending error frames

• When RNR was received partway through a block and then T5 runs out.

If a page needs two blocks, or if T5 runs out, the page is separated into two blocks.



EOR vs CTC

This manufacturer's machines use EOR as little as possible.

If all frames within a block cannot be corrected within four tries (this includes the original attemptand three retries), the machine will send CTC and modem rate fallback will be used.

After fallback, if the block is sent correctly, the next block will be sent either at the original ratebefore fallback or at the successful rate (after fallback). There is an adjustment to select whichmethod is used.

If the modem rate is 2,400 bps and the data still cannot be sent correctly, the machine will sendEOR, and will go on to send the next block of data.

Page printout timing

Normally, data is printed while it is received. However, if an error frame is received, printoutstops at that point. When the error frames are resent, the page is printed again from the pointwhere it left off.

If one of this manufacturer's machines receives EOR, the block is printed up to the first errorframe, then the line is cut.



SEP/PWD/SUB/SID Signals

The ITU-T recommendations were changed in 1996 to allow pollincommunications. Before, these could only be done between RicoNSF/NSS. Now, these features can be used between any maker’sSUB, and other new signals.

Secured Polling using SEP/PWDSEP Signal: When the Rx terminal receives the SEP signalwith the NSC or DTC signal, the Rx terminal switches over tosecured polling transmission using the SEP ID. The SEP(Selective polling) signal must contain four digits as an ID.

The Rx terminal automatically disconnects the line when any ofthe following conditions occurs (error code 0-15).

• When the SEP ID is other than four digits• When anything other than numbers is included in the ID

The communication becomes free polling when the SEP ID is0000.

PWD Signal: When the PWD (password) signal is transmittedtogether with the SEP signal, the PWD programmed is used asan ID code for stored ID override.

H

9 August 2003

Protocol

g and confidentialh-made terminals, using machines, using the SEP,

Tx Rx

CED

NSF

DIS

SEP

NSC or DTC

NSS or DCS

CFR

TCF

551d501.wmf

Page 709


Confidential ID Override using SUB/SIDSUB Signal: The SUB (sub-address) signal transmitted from the Txterminal contains a confidential ID. A stored message can beprinted using the SUB ID as confidential ID override.

The SUB ID must contain four digits. The receiving terminalautomatically disconnects the line when any of the followingconditions occurs (error code 0-15).

• When the SUB ID is other than four digits• When anything other than numbers is included in the ID• When a confidential ID is not programmed in the Rx terminal and

when the transmitted SUB ID is 0000

A stored message can be printed using the (normal) confidential IDstored in the machine when the SUB ID sent from the transmitter is0000.

Tx Rx

CED

NSF

DIS

SUB

NSS or DCS

CFR

TCF

H551d502.wmf



V.8/V.34 Protocol

Overview

New Recommendations

ITU-T modified T.30 in 1996 to include changes to protocol signaling as a result of V.8procedure implementation.

If V.8/V.34 signaling is used, ECM must also be used.

Phases Of The V.34 Procedure

The protocol procedure for a V.34 fax communication consists of 6 phases. The followingexplain the phases briefly.

Phase 1: V.8 SequenceThe calling and called terminals exchange available modulation modes (fax or data modem) anddata transmission direction information, and decide a communication mode.

Phase 2: Line ProbingThe receiving terminal determines the available bandwidth for the fax data transmission channel(known as the primary channel) based on the analysis of line probing signals sent from thetransmitting terminal. This bandwidth is informed to the transmitting side as a symbol rate.



Phase 3: Primary Channel Equalizer TrainingThe receiving terminal adjusts its equalizer etc., while receiving training signals from the sender.The tx side uses the data transmission modulation parameters informed by the rx side at the endof phase 2.

Phase 4: Control Channel Start-upBoth terminals determine a data rate for the primary channel (in other words, for datatransmission).

Phase 5: Control ChannelBoth terminals exchange T.30 protocol signals (DIS/DCS, NSF/NSS) to determine transmissionparameters (this equivalent to phases B and C of T.30 protocol)

Phase 6: Primary ChannelThe sending terminal sends fax image data at the data rate that was determined with thereceiver in phase 4. One ECM block is sent at a time.

Post Message ProcedureAfter the primary channel has finished, both terminals restart the control channel to exchangepost message signals, as former fax machines do in phase E of T.30 protocol.If there is another ECM block to send, the machines then start the primary channel again,otherwise they disconnect the line.



Protocol OverviewThis shows a one page fax transmission with nospecial features and no errors.

The time required for the communication (one ECMblock) is approximately as follows:Until the end of phase 5: About 6 to 7 sPhase 6: About 3 sPost-message: About 2 s

Total: About 11 to 12 s

TX RX

CNG

ANSam

CM

JMCJ

1100 Hz

2100 Hz

300 bps

300 bps

300 bps

INFO0c

1200 Hz

600 bpsINFO0a

B

A

B bar

A bar

L1

L2

BA

INFOh

1200 Hz

2400 Hz

2400 Hz

2400 Hz1200 Hz

600 bps

600 bps

Spectrum

Spectrum

(Symbol Rate, etc.)

S

S bar

PP

TRN

PPh

1200 bps ALT

MPh

E

(Data Rate, etc.)

PPh

ALT

MPh

E

MPh

MPh

1200 bps

1200 bps

1200 bps

1200 bps

1200 bps

or

1's

Flag

CFR

NSF

(Silence)

1200 bps

CSI

DIS

Flag

1200 bpsFlag

NSS TSI

DCS

Flag

TX RX

(Pix Data)

S

S bar

PP

B1

PrimaryChannel

Turn-off

Sh

1200 bps ALT

E

ALT

E 1200 bps

1200 bps

1200 bps

Sh bar Sh

Sh bar

1's

Flag

MCF

(Silence)

Flag

PPS-EOP

DCN

Flag

75

ms

75

ms

70

ms

70

ms

70

ms

70

ms

Ph

as

e 1

(V.8

Pro

ce

du

re)

Dial

Disconnect Disconnect

Ph

as

e 2

(Lin

e P

rob

ing

)

Ph

as

e 3

(Pri

ma

ry C

h.

EQ

.T

rain

ing

)

Ph

as

e 4

(Co

ntr

ol

Ch

. S

tart

-up

)P

ha

se

5(C

on

tro

l C

ha

nn

el)

Ph

as

e 6

(Pri

ma

ry C

ha

nn

el)

Ph

as

e 4

(Co

ntr

ol

Ch

. R

es

tart

)

Ph

as

e 5

(Co

ntr

ol

Ch

an

ne

l)P

os

t M

es

sa

ge

V.8/V.34 Protocol Sequence (1 page/ 1 block)

Lower Frequency

Higher FrequencyYou hear higher frequency signals inphases indicated with light gray.

You hear lower frequency signals inphases indicated with dark gray.

Symbol Rate(baud)

Data Rate(kbps)

2400 2800 3000 3200 3429

33.6

31.2 31.2

28.8 28.8 28.8

26.4

24.0

21.6

19.2

16.8

14.4

12.0

9.6 9.6 9.6 9.6 9.6

7.2 7.2 7.2 7.2 7.2

4.8 4.8 4.8 4.8 4.8

2.4

21.6

19.2

16.8

14.4

12.0

21.6

19.2

16.8

14.4

12.0

21.6

19.2

16.8

14.4

12.0

21.6

19.2

16.8

14.4

12.0

26.4

24.0

26.4

24.0

26.4

24.0

Single-page-tx.wmf



Basic Procedure

Phase 1: V.8 Sequence

Overview

V.8 protocol establishes communicationbetween the calling modem and the answeringmodem. The general communication functionsand modulation modes are exchanged. Thebest modulation mode for the calling andanswering modems is determined upon theexchange of call menu (CM) and joint menu(JM) signals.

ANSam• 2100Hz, amplitude modulated using 15Hz

cosine wave, phase inverted every 450 msCM (V.21L)/JM (V.21H)• Full duplex• Modulation mode• Data directionCJ (V.21L)• Phase 1 end

Calling Called

CNG

ANSam

CM

JMCJ

1100 Hz

2100 Hz

300 bps(V.21H)

300 bps(V.21L)

300 bps(V.21L)

Full Duplex

Ph_1.WMF



Signals

CNG(Call indicator)

Transmitted from the calling terminal to indicate the start of acommunication.

ANSam Amplitude-modulated, phase inverted 2100 Hz signal.CM

(Call menu signal)Transmitted from the calling terminal primarily to indicate itsavailable modulation modes, and to inform whether it issending data or wishes to receive data by polling.

JM(Joint menu signal)

Transmitted from the receiving terminal primarily to indicatethe modulation modes available in both terminals.

CJ(CM terminator)

Acknowledges the detection of a JM signal and indicates theend of the CM signal. CJ ends this phase of thecommunication.



Procedure

Calling Terminal Called TerminalAfter dialing, the machine sends CNG signaland waits for an ANSam signal.

After ring detection, the called terminal sendsANSam signal for up to 3.2 s, while waiting fora CM signal from the calling terminal. (See thenote after the table.)

After ANSam detection, the machine sends CM,while waiting for a JM.CM settings:• Normal transmission: 81 85 D4• Polling reception: A1 85 D4After JM detection, the machine sends CJ.

After CM detection, the machine sends JM,while waiting for a CJ.JM Settings

• Normal reception: 81 85 D4• Polling transmission: A1 85 D4

Both terminals go into phase 2 (line probing) 75 ms after CJ .

- ANSam -

After detecting CNG, the called terminal sends ANSam. This starts the V.8 sequence.

The ANSam signal is a 2100 Hz tone signal that is amplitude modified with a 15Hz-cosine wave.Also, the signal phase of ANSam inverts every 450 ms. The frequency is the same as the CEDtone.

Some fax machines cannot detect the 15Hz cosine wave modulation and phase inversion, andthink that ANSam is a CED tone.



- CM, JM -

The exchange of CM and JM signals is next. These are sent in accordance with V.21modulation. CM is sent with a low carrier frequency (V.21L), and JM is sent at a higher frequency(V.21H). Because of this, the CM/JM exchange is full duplex (the signals are sent at the sametime, because they do not interfere with each other).

• Digital networks that have a sampling rate of 8 kbps cannot pass CM and JM. CM cannotreach the called terminal, so the called terminal falls back to V.17 mode. V.34 communicationwill not be possible.

The machines inform what type of modem they have (fax modem or data modem). If acommunication mode (e.g., V.34 fax communication to calling terminal to called terminal) isavailable at both terminals, the terminals communicate using that communication mode for thesubsequent phases.

• If no communication mode is commonly available at both sides (for example, if a fax modemhas called a data modem), both terminals disconnect the line after the JM and CM signals.

The calling terminal informs whether it wants to send data or receive data. From this point, thedata sender becomes the Tx terminal, and the receiver becomes the Rx terminal. Note that forpolling, the calling terminal becomes the Rx terminal.

• The communication ends if the receiver of a polling request does not have files on pollingstandby.



- CJ -

This signals the end of the CM/JM exchange.

After 75 ms, phase 2 will begin

Refer to Advanced Procedures Various V.8 Sequences for examples of various V.8 sequences.

NOTE: The ITU-T recommendation for the ANSam length is 2.6 to 4.0 s. Ricoh uses 3.2 s (as ofFebruary, 1998).

If no response to an ANSam signal is detected within the maximum signal duration, it isassumed that V.8 protocol is not supported, and communication takes place inaccordance with recommendation T.30.

Error Codes

• 0-70: Refer to Possible Errors Phase 1.• 0-74: Refer to Possible Errors Phase 1.• 0-75: Refer to Possible Errors Phase 1.• 0-76: Refer to Possible Errors Phase 1.• 0-77: Refer to Possible Errors Phase 1.



Phase 2: Line Probing

Overview

Phase 2 establishes the condition of theline, which decides the bandwidth availablefor the communication.

INFO0c/INFO0a• Modem capabilities• Modulation parametersL1/L2• Probing tone• L1>L2 (by 6dB)INFOh• Symbol rate (carrier frequency)• Pre-emphasis• Power reduction

TX RX

INFO0c

1200 Hz

600 bps INFO0a

B

A

B bar

A bar

L1

L2

BA

INFOh

1200 Hz

2400 Hz

2400 Hz

2400 Hz1200 Hz

600 bps

600 bps

Spectrum

Spectrum

(Symbol Rate, etc.)

Ph_2.WMF



The aim of phase 2 is to determine a set of modulation parameters that will be used in phase 6(the primary channel) for image data transmission.

Both modems exchange information about their capabilities and modulation parameters usingINFO0c and INFO0a signals. Then the transmitting terminal sends L1 and L2, which are knownas probing tones. These tones allow the receiving modem to analyze the network qualities, suchas bandwidth and noise level.

Based on its analysis of how well the network passed the probing tones, the receiving modeminforms a set of modulation parameters, such as symbol rate, pre-emphasis, and powerreduction, using the INFOh signal.

Both modems then go into phase 3 (equalizer training) 70 ms after INFOh.



Signals

INFO0c A signal transmitted from the calling terminal to indicate its availablemodem capabilities and data mode modulation parameters.

INFO0a A signal transmitted from the receiving terminal to indicate itsavailable modem capabilities and data mode modulation parameters.

B A modem control signal of 1200 Hz.B bar The same as B, but with phase inverted.

A A modem control signal of 2400 Hz.A bar The same as A, but with phase inverted.

L1 A line probing signal to analyze line characteristics. L1 is 6 dB higherthan L2. This signal is used to check the amplitude distortion.

L2 A line probing signal to analyze line characteristics. This signal isused to check the amplitude distortion.

INFOh A signal used by the receiving terminal to inform the results of lineprobing. The symbol rate is informed by this signal.



Procedure

Sender Terminal Receiver Terminal75 ms after the end of phase 1, themachine sends INFO0c.

75 ms after the end of phase 1, themachine sends INFO0a.

When the machine detects an INFO0a, itstops INFO0c and sends B and B bartones.

When the machine detects an INFO0c, itstops INFO0a and sends A and A bartones.

When the machine detects A bar, it sendsline-probing signals (L1 and L2).

When the machine detects B bar, it startswaiting for line-probing signals (L1 andL2).

After L2 has finished, the machine sends Btone again.When the machine receives an INFOhsignal, it stops B.

After L2 reception has finished, themachine sends A tone again followed byINFOh signal

Both terminals go into phase 3 (control channel start-up) 70 ms after above steps.

- INFO0c, INFO0a -

The two machines exchange their modem capabilities and the available modulation parameters.

- A, A bar, B, B bar -

The two machines exchange 2400Hz and 1200Hz tones with phase reversals.

• V.34 provides for full duplex and half duplex modes for fax communication. In full duplexmode, these signals determine any delay to signal round trip time caused by line conditions.



However, current fax machines use half-duplex only, so the round trip time calculation is notused.

- L1, L2 -

The tx side transmits a series of tones, in a very short period of time, ranging from 150 Hz to3750 Hz. These are known as probing tones.

The table shows the range of frequenciesthat the tx side sends to the rx side in the L1and L2 signals. As can be seen, the phasesometimes reverses.

The rx side analyses how the signals arereceived. Based on the results, the rx sidedoes the following:

• Decides the available bandwidth for datatransfer, by specifying a symbol rate. Thepoorer the line, the narrower thebandwidth.

• Requests the tx side to adjust the pre-emphasis and power reductionparameters, so that the rx side canoptimize reception across the bandwidth.

The rx side informs the above to the tx sidein the INFOh signal.

cos (2ππππft + ϕϕϕϕ)

ϕϕϕϕ (degrees)

180

0

180

0

180

180

180

180

0

0

f (Hz)

2250

2550

2700

2850

3000

3150

3300

3450

3600

3750

ϕϕϕϕ (degrees)

0

180

0

0

0

0

0

0

180

0

0

f (Hz)

150

300

450

600

750

1050

1350

1500

1650

1950

2100

PROBING TONES.WMF



- INFOh -

The receiving terminal informs the results of the line probing.

70 ms later, phase 3 begins.

The results include pre-emphasis, power reduction, and symbol rate.

Symbol Rate

The symbol rate is a baud rate. However, the data can be modulated in different ways using thissymbol rate to achieve different data rates. If the line condition is good, a higher data rate will beselected. The data rate is selected in phase 4 (see the section on phase 4).

This means that the actual data rate for fax communication has not been decided yet.

The maximum data rate of 33.6 kbps is only possible if a symbol rate of 3429 can be used.

ITU-T also lists 2743 as a possible symbol rate. However, at the time of writing, the two makersof V.34 modems (Panasonic, Rockwell) did not support this symbol rate.

The following table and diagram show the required bandwidths for V.27, V.29, V.17, and thevarious V.34 symbol rates. Bandwidth is one of the important factors the modems use to select asymbol rate. As shown in the table, the faster the modulation, the wider the required bandwidth.This is because required bandwidth for a modulation depends on symbol rate and carrierfrequencies.



Other factors determining the symbol rate are signal to

3k Hz

2k Hz

1k Hz

0

3.5k Hz

1200

2400

1000

2600

500

2900

600

3000

400

2800

600

3000

280

467300

500

229320

245

3080

3267 3300

3500 34293520

3674

V.27(2.4k)

V.27(4.8k) V.29 V.17 V.34

(2400)V.34

(2800)V.34

(3000)V.34

(3200)V.34

(3429)

9 August 2003

Protocol

noise levels.

Symbol Rate(baud)

2400

2800

3000

3200

3429

CarrierLow/High

1600/1800 Hz

1680/1867 Hz

1800/2000 Hz

1829/1920 Hz

1959/1959 Hz

RequiredBandwidth (Hz)

400 - 2800 Hz (L)600 - 3000 Hz (H)

280 - 3080 Hz (L)467 - 3267 Hz (H)

300 - 3300 Hz (L)500 - 3500 Hz (H)

229 - 3429 Hz (L)320 - 3520 Hz (H)

245 - 3674 Hz

Modem

V.34

V.17 2400 1800 Hz 600 - 3000 Hz

V.29 2400 1700 Hz 500 - 2900 Hz

V.27 (4800) 1600 1800 Hz 1000 - 2600 Hz

V.27 (2400) 1200 1800 Hz 1200 - 2400 Hz

CARRIER FREQ TABLE.WMF

Page 725


Pre-emphasis

This is a linear equalization method where the transmitted signal spectrum is shaped tocompensate for attenuation distortion.

Power reduction

When the received signal is too strong, the rx side asks the tx side to reduce the tx level by up to7 dB.

Error Codes

• 0-80: Refer to Possible Errors – Line Probing and Training



Phase 3: Primary Channel Equalizer Training

Overview

The tx side sends training signals using the data transmissionmodulation parameters informed by the rx side at the end ofphase 2.

The fax data transmission channel is known as the primarychannel.

Tx side• Sends training signals using the modulation parameters

decided in INFOh.Rx side• Modem equalizer training• Data rate determination• AGC adjustment

TX RX

S

S bar

PP

TRN

Ph_3.wmf



Signals

S, S barPP Training signals

TRN

The receiver modem monitors the phase 3 signals and adjusts its equalizers and AGC(Automatic Gain Control).

In addition, the receiving modem selects a data rate (bps) from the possible range specified bythe agreed symbol rate – this will be used in phase 6 (primary channel). However, at this point,the tx side still is not aware of the rate that has been decided - it is not informed until the nextphase.

Both modems then go into phase 4 (control channel start-up) 70 ms after TRN.

Recovery Procedure

If the receiving modem does not detect S within 2 seconds or if a TRN error is detected, thereceiving modem goes back to the last part of phase 2 to restart sending signal A.

After detection of signal B, the receiving modem sends INFOh and tries again to detect S.



Error Codes

• 0-81: Refer to Possible Errors Line Probing and Training.



Phase 4: Control Channel Start-Up

Overview

The aim of control channel start-up is todecide the modulation parameters that willbe used in the control and primarychannels.

• Control channel: T.30 fax controlprotocol

• Primary channel: Fax data transmission

MPh

• MPh from rx side determines modulationparameters

• Primary ch. data rate• Control ch. data rate• Type 0: Tx to Rx• Type 1: Rx to Tx

E

• Start of control channel

TX RX

PPh

1200 bps ALT

MPh(Type 0)

E

(Data Rate, etc.)

ControlChannel

PPh

ALT

MPh(Type 1)

E

MPh(Type 0) MPh

(Type 1)

1200 bps

1200 bps

1200 bps

1200 bps

1200 bps

ControlChannel

Ph_4.wmf



Signals

PPh PPh is a signal for control channel receiver initialization and resynchronization.ALT A scrambled series of alternating 0s and 1s at 1200 bps.MPh MPh contains the modulation parameters that will be used for data mode

transmission, such as control channel data rate and primary channel data rate.The sender uses type 0 only., and the receiver uses type 0 or type 1. The type 1 MPhcontains additional parameters to the type 0 MPh.

E E is a 20-bit scrambled signal to inform the beginning of the control channel (phase5).

The sending terminal informs its of modulation parameter capabilities using a type 0 MPh signal.Using a type 0 or type 1 MPh signal, the receiver informs the set of modulation parameters that itdecided while receiving training signals in phase 3.

The MPh sent from the tx side is a Type 0 MPh, and from the Rx side it is a Type 0 or Type 1MPh (mostly, it is Type 1).

• The Type 1 signal contains some coefficients that will be used for pre-coding (pre-coding is anon-linear equalization technique).

If the initial transmission or reception data rate is changed by bit switches or dedicated txparameters, the new setting is reported in the MPh signals.

The signals in this phase use 1200 bit/s, 600 symbols/s QAM modulation.



Procedure

Sender Terminal Receiver Terminal70 ms after the end of phase 3, the machinesends PPh and ALT.

After detecting a PPh from the sender, themachine sends PPh and ALT

The machine sends MPh signals while waiting forMPh from the other machine.

The machine sends MPh signals while waitingfor MPh from the other machine.

After detecting a MPh from the receiver, themachine stops MPh and sends E.

After detecting a MPh from the sender, themachine stops MPh and sends E.

Both terminals go into phase 5 (control channel).

- MPh -

The rx side informs the data rate that it decided as a result of phase 3. The data rate will be oneof those possible with the previously agreed symbol rate (see the next page).

The control channel rate is always set to 1200 bps. There is an option for 2400 bps, but it is notused at the moment.

The final MPh from the rx side contains the data rate information.

NOTE: 1) If the sender receives signal A while waiting for an MPh signal, it goes back to phase2, and sends signal B and prepares to receive INFOh.

2) If either terminal fails to start up the control channel, it sends AC tone. Refer to‘Possible Errors – Control Channel Start-up – Error Recovery Using the AC Tone’ fordetails on the recovery sequence after the AC tone.



Data Rates and Symbol Rates

The above table shows the available data ratesfor each symbol rate.

In the MPh signals, both terminals must inform adata rate that is available with the symbol ratewhich was decided in phase 2 (INFOh signal).

Error Codes

• 0-82: Refer to Possible Errors – ControlChannel Start-up/Restart.



Symbol Rate(baud)

Data Rate(kbps)

2400 2800 3000 3200 3429

33.6

31.2 31.2

28.8 28.8 28.8

26.4

24.0

21.6

19.2

16.8

14.4

12.0

9.6 9.6 9.6 9.6 9.6

7.2 7.2 7.2 7.2 7.2

4.8 4.8 4.8 4.8 4.8

2.4

21.6

19.2

16.8

14.4

12.0

21.6

19.2

16.8

14.4

12.0

21.6

19.2

16.8

14.4

12.0

21.6

19.2

16.8

14.4

12.0

26.4

24.0

26.4

24.0

26.4

24.0

Data and Symbol Rates.wmf



Phase 5: Control Channel

Overview

In the control channel, both terminalsexchange T.30 protocol signals. However, thedata rate is 1200 bps, as opposed to the 300bps used with V.21 signaling.

Since both terminals (modems) havedetermined a modulation mode and a set ofmodulation parameters in the previousphases, the machines do not repeat thosesettings in the NSF or DIS signals.

“0000” is set in bits 11 to 14 of the DIS/DCSsignals (initial modem rate).

In this phase, a flag sequence is transmittedwhenever there is no data to transmit (thisapplies to both Tx and Rx terminals).

Silence (or the absence of flags) from the Rxside indicates the end of this phase.

TX RX

or

1's

E

Flag

CFR

NSF

(Silence)

1200 bps

E

CSI

DIS

Flag

1200 bpsFlag

NSS TSI

DCS

Flag

Ph_5.wmf



Procedure

The procedure in this phase is the same as phases B and C of T.30 protocol, except thefollowing.

• The receiver terminal always responds with CFR. It never uses the training signal responsesTCF and FTT.

• Modem type and speed are not included in the negotiated parameters. However, machinecapabilities are exchanged (such as paper size, the availability of duplex printing, and so on).

• Both machines sends flags while they do not send data.• When the tx side detects CFR, it starts to send 1's. When the rx side has detected 40

consecutive 1's, it stops flag transmission and prepares to receive fax data.• When the tx side has detected silence from the other side, it starts the next phase



Phase 6: Primary Channel

Overview

S, S bar, PP Training signalsB1 A signal to inform the beginning of user

data.

The primary channel is used for image datacommunication. It uses the data rate which wasdetermined in phase 4 (MPh) and the symbol rate thatwas specified in phase 2 (INFOh).

One primary channel contains one ECM block. If a page issplit into two blocks, it requires two primary channels to betransmitted. (Refer to Multi-page Control for details on howthis is done.)

• Note that it is split up into ECM blocks, not pages.

TX RX

(Fax Data)

S

S bar

PP

B1

PrimaryChannel

Turn-off

Ph_6.wmf



An ITU-T chart takes about 3 seconds.

• This is from the S signal to the turn-off.• Group 4 is also specified as 3 seconds for one ITU-T #1 chart, but the resolution is different.

V.34 Group 3: Standard resolution 8 x 3.85 dots/mmGroup 4: Detail resolution 200 x 200 dpiGroup 4 sends twice as much image data in the same time.

Error Code

• 0-87: Refer to Possible Errors – Primary Channel.



Control Channel Restart

Overview

After an ECM block has been sent, the controlchannel restarts so that the terminals can exchangepost-message signals.

Signals

Sh, Sh bar Training signals, similar to S and Sbar, but sent using the controlchannel modulation

PPh PPh is a sequence for controlchannel receiver initialization andresynchronization. This is usedinstead of Sh if a change inmodulation parameters is desired forthe next page.

ALT A scrambled series of alternating 0sand 1s at 1200 bps

E E is a 20-bit scrambled sequence of1s at 1200 bps to signal thebeginning of control channel data.

TX RX

Sh

1200 bps ALT

E

ControlChannel

ALT

E 1200 bps

1200 bps

1200 bps

ControlChannel

Sh bar Sh

Sh bar

PH_4_RESTART.WMF



This phase is similar to phase 4. The signals are similar to phase 4, except instead of using aPPh – MPh sequence, an Sh sequence is used.

During control channel restart, either terminal can request a change in the data rate. In suchcases, the requesting terminal will send PPh instead of Sh, and MPh will be used to decide thenew data rates for the next block of fax data.

NOTE: Also, if an error occurs during control channel restart, a PPh – MPh sequence is usedinstead of Sh.

Procedure

Sender Terminal Receiver Terminal70 ms after the end of phase 6, themachine sends Sh, Sh bar, and ALT.

After detecting a Sh from the sender, themachine sends Sh, Sh bar, and ALT

After detecting a Sh bar from the receiver,the machine stops ALT and sends E.

After detecting a Sh bar from the sender,the machine stops ALT and sends E.

Both terminals go into the post message procedure (control channel).

NOTE: If the sender receives signal A while waiting for an MPh signal, it goes back to phase2, and sends signal B and prepares to receive INFOh.

Error Codes

• 0-83: Refer to Possible Errors – Control Channel Start-up/Restart.• 0-85: Refer to Possible Errors – Control Channel Start-up/Restart.



Post Message Procedure (Control Channel)

Overview

This phase is similar to phase 5.

In this phase, both terminals use the control channel toexchange T.30 end-of-page or end-of-message signals(T.30 phase E protocol).

Data communication errors are reported using ECMprotocol, and retransmission of parts with errors isrequested.

When the sender detects silence, it stops sending theclosing “1’s” and disconnects the line.

9 August 2003

Protocol

TX RX

1's

E

Flag

MCF

(Silence)

E

Flag

PPS-EOP

DCN

Flag

Ph_5_Post_Message.wmf

Page 740


Procedure

Procedure in this phase is the same as phase E of T.30 protocol, except the following.

• Both machines sends flags while they do not send data.• When the receiving terminal detects 40 consecutive “1’s”, it stops flag transmission.

If there were errors, there is a PPS – PPR exchange in accordance with T.30 ECM protocol, thenthe error frames are resent in the primary channel. Then the control channel is restarted and theline is disconnected (or the next ECM block prepared for).

If there are no more ECM blocks to send, the sender terminal transmits DCN. Then the receiverstops flag transmission and disconnects the line.

For the multi-block transmission sequences, using PPS-MPS and PPS-EOM, refer to AdvancedProcedures – Multi-page Control.



Advanced Procedures

Various V.8 Sequences

Non-V.8 to V.8

The called V.8 terminal transmits ANSam until thetimer expires, then falls back to V.17 to transmitNSF/CSI/DIS.• The calling side (non-V.8) thinks that ANSam is

CED, and waits for NSF/DIS as usual for T.30procedure.

• When the called side cannot detect JM in reply toANSam within 3.2 s, it drops back to V.17/T.30and sends NSF/CSI/DIS.

NOTE: The ANSam timeout can be anythingfrom 2.6 s to 4.0 s. Ricoh has decidedon 3.2 s as a result of various evaluation and

9 August 2003

Protocol

compatibility tests.

3.2 secmax.

TX RX

CNG

ANSam

NSF

1100 Hz2100 Hz

TSI

CSI

DIS

DCS

NSS

Timeout

V.8 available

V.8 available

Ph_1 (non-V8 to V8).WMF

Page 742


If the calling terminal has a communication record forthe receiver using AI short protocol, the communicationcan step down to V.17/T.30 more quickly. The Tx sidesends an 800Hz tone immediately after detecting2100Hz. The called V.8 terminal then stops ANSam toreceive NSS(A), which follows immediately.

NOTE: The machine needs 0.4 s to detect 2100Hz.

V.8 to Non-V.8

The calling side checks the 2100Hz signal for amplitudemodulation and phase inversion to see if it is an ANSam.

If the calling side cannot detect ANSam within 2 s, it fallsback to V.17 and waits for an NSF or DIS signal.

NOTE: The machine needs 0.4 s to detect 2100Hz, thenwaits for 2 more seconds (2.4 s in total) whiletrying to detect ANSam characteristics (such asphase reversals).

9 August 2003

110

Protocol

TX RX

CNG

ANSam

0 Hz2100 Hz

800 Hz

NSS(A)

400 ms min.

Ph_1 (AI to V8).WMF

about 2.4 s

TX RX

CNG

CED

NSF

1100 Hz2100 Hz

TSI

CSI

DIS

DCS

NSS

ANSam notdetected.

Ph_1 (V8 to non-V8).WMF

Page 743


If the calling V.8 terminal has a communicationrecord for the receiver using AI short protocol, thecommunication can step down to V.17/T.30 morequickly. The calling V.8 terminal sends an 800Hztone 500 ms after 2100Hz detection, instead of after2 seconds.

NOTE: The machine needs 0.4 s to detect2100Hz, then waits for 0.5 moreseconds (0.9 s in total) while trying todetect ANSam characteristics.

9 August 2003

Protocol

900 ms

TX RX

CNG

CED

1100 Hz2100 Hz

800 Hz

NSS(A)

ANSam notdetected.

Ph_1 (V8 AI to non-V8).WMF

Page 744


Manual Tx (Non-V.8 to V.8)

Manual transmission from a non-V.8 terminal is thesame as former T.30 protocol.

TX RX

CNG

ANSam

NSF

1100 Hz

2100 Hz

CSIDIS

Start

NSFCSIDIS

T4timer

TSI

DCS

NSS

V.8 available

V.8 available

PH_1 (MANUAL TX TO V8).WMF



Manual Tx (V.8 to V.8)

The calling side misses the first ANSam andthe communication drops out of V.8 mode toV.17.

However, if the calling side detects that V.8 isavailable (the V.8 bit in NSF/DIS is on), it asksthe called side to restart V.8 from the beginningwith a CI (Call Initiation) signal.

NOTE: As of February 1998, Ricoh V.34 faxmachines do not support V.8 in manualtransmission. Fax machines from othermanufacturers may support thissequence.

TX RX

CNG

ANSam

NSFCSIDIS

Start

NSFCSIDIS

T4timer

V.8 available

V.8 available

ANSam

CI

JMCMCJ

V.8restart

PH_1 (MANUAL TX V8).WMF



Manual Rx (Non-V.8 to V.8)

This is the same as non-V.8 to V.8 faxcommunication (described earlier)

Immediately after the operator at the called sidepresses Start, the called side sends ANSam for3.2 s, then drops back to V.17 communicationbecause there is no V.8 response from the caller.

NOTE: 1) The ITU-T recommendation of theANSam length is 2.6 to 4.0 s. Ricohuses 3.2 s (as of February 1998).

2) V.8 sequence in manual reception is amachine specific function (as ofFebruary 1998). Refer to themachine’s service manual for theavailability of V.8 in manual reception

3.2 secmax.

TX RX

CNG

ANSam

NSF

TSI

CSIDIS

DCSNSS

Timeout

CNG

Start

PH_1 (MANUAL RX NON-V8).WMF



Manual Rx (V.8 to V.8)

Immediately after the operator at the calledside presses Start, the called side sendsANSam.

The calling side immediately sends CM if itis a V.8 terminal, and V.8 signalling cancontinue.

NOTE: V.8 sequence in manualreception is a machine specificfunction (as of February 1998).Refer to the machine’s servicemanual for the availability of thisfunction.

TX RX

CNG

ANSam

JMCM

CJ

CNG

Start

PH_1 (MANUAL RX V8).WMF



Polling

In phase 1, the calling terminal uses the CM signal toindicate polling reception, and the receiving terminalacknowledges it in the JM signal. Then the directionof communication is reversed (the called sidebecomes a transmitter and the calling side becomesa receiver).

In phase 2, the called terminal (sender) transmitsline-probing signals, L1 and L2, and the callingterminal (receiver) transmits INFOh. All other signalsgo in the same direction as normal V.34communication.

In phases 3 and 6, the data goes from the calledterminal to the calling terminal.

Note that polling is the only fax feature to beinformed in phase 1. All the others (confidential tx,etc.) are informed in phase 5. If polling with ID is tobe used, this is informed in phase 5.

CNG

ANSam

CM

JMCJ

INFO0c INFO0a

B A

B bar A bar

L1

L2

B

AINFOh

Spectrum

Spectrum

(Symbol Rate, etc.)

Dial

SS barPP

TRN

TXRX

Polling.wmf



Multi-Page Control

Strictly speaking, this is multi-ECM-block control, as eachprimary channel transmission sends one ECM block. If apage requires more than one ECM block, it will be divided intotwo primary channels.

PPS-MPS

If the sender does not want to use new settings for the nextblock, it sends PPS-MPS in the control channel. The receiverthen responds with MCF or PPR (see below).

Then, both terminals close the control channel restart phase.Then, the Tx side restarts the primary channel..

- MCF (Message Confirmation) -

If the receiver received previous the ECM block completely(with no errors), it sends MCF. Image data in the next primarychannel will be the next ECM block.

- PPR (Partial Page Request) -

If the receiver did not receive the previous ECM blockcompletely, it sends PPR. Image data in the next primarychannel will be retransmitted error frames from the sameECM block.

9 August 2003

Protocol

(Fax Data)PrimaryChannel

Turn-off

Sh

ALTE ALT

E

Sh bar ShSh ba

1's

Flag

MCF

Flag

PPS-MPS

Flag

SS barPPB1

PrimaryChannel

TX RX

(Next page)

P t (PPS MPS) WMF

Page 750


PPS-EOM

If the sender terminal has another block and wantsto change the settings, it sends PPS-EOM in thecontrol channel. The receiver then responds to thesender with either of the following.

- MCF (Message Confirmation) -

If the receiver received the previous ECM blockcompletely, it sends MCF. After the T2 timer (6 s)expires, the receiver sends T.30 phase B signals(NSF/DIS) to exchange new communication settingsagain. The following procedure is the same asphase 5.

Image data in the next primary channel will be thenext block.

- PPR (Partial Page Request) -

If the receiver did not receive the previous ECMblock completely, it sends PPR. The receiver thengoes back to the primary channel to resend the errorframes. There is no change of communicationsettings at this time.

9 August 2003

Protocol

(Pix Data)PrimaryChannel

Turn-off

Sh

ALTE ALT

E

Sh bar ShSh bar

Flag

MCF

Flag

PPS-EOM

Flag

TX RX

or

1's

Flag

CFR

NSF

(Silence)

CSIDIS

Flag

NSS TSIDCS

Flag

Primary channel (Phase 6)

6 stimeout

Post message (PPS-EOM).WMF

Page 751


Data Rate Change Request

Overview

According to ITU-T recommendations, either the sender or the receiver can initiate a rate changerequest in the control channel restart phase using a PPh – MPh sequence, during acommunication. However, the recommendation does not specify any request conditions. So, theconditions depend on each manufacturer.

NOTE: This section explains how either terminal requests a rate change, but does not explainrequest conditions. Refer to the machine’s service manual for the condition in which themachine requests a rate change.



Request from Receiving Terminal

This is an example of a one-step shift-down requestfrom the receiving terminal due to several partialpage requests (there were a lot of errors in thereceived data).

The sender restarts the control channel using an Shsequence. Then, the receiver responds to it with PPhinstead of an Sh. This signifies that a rate changerequest is coming up. The sender can then start aPPh – MPh sequence. The MPh signals from the rxside determine the new data rate.

Both terminals then exchange modulationparameters again to decide a new data rate for thenext primary channel. The new rate must beavailable using the same symbol rate as theprevious data rate. (The line conditions have notbeen tested again with L1 and L2, so it is unsafe totry a wider bandwidth.)

9 August 2003

Protocol

Fax Data(e.g., 33.6kbps)

PrimaryChannel

Turn-off

Sh

ALT

E

ALT

E

Sh bar PPh

1's

Flag

PPR

Flag

PPS-MPS

Flag

SS barPPB1

PrimaryChannel

TX RX

MPhMPh MPh

MPh

PPhALT


Ratechangerequest

RATE CHANGE (RX TO TX).WMF

Page 753


Request from Sending Terminal

This is an example of a one-step shift-up requestfrom the sender terminal.

The sender restarts the control channel using a PPhsequence instead of an Sh. Then, the receiverresponds to it with PPh, which enables the sender tostart a PPh – MPh sequence as both terminals did inphase 4.

Both terminals then exchange modulationparameters again to decide a new data rate for thenext primary channel. The new rate may be higheror lower, depending on how previous blocks werereceived. It must be available using the samesymbol rate.

9 August 2003

Protocol


PrimaryChannel

Turn-off

ALT

E

ALT

E

PPh

1's

Flag

MCF

Flag

PPS-MPS

Flag

SS barPPB1

PrimaryChannel

TX RX

MPhMPh MPh

MPh


Ratechangerequest

PPh

RATE CHANGE (TX TO RX) WMF

Page 754


Possible Errors

Phase 1 (V.8)

Error Code 0-70

NOTE: This error code can be generated by either the callingor called terminal.

If the communication modes specified in CM and JM do notmatch, both terminals disconnect the line after the V.8sequence.

This error can occur in the following cases.

• A V.34 fax terminal called a V.34 data terminal, or viceversa.(JM = C1 05 10 10 for a data terminal)

• The calling terminal requested polling reception, but thecalled terminal did not have a polling transmission file (ordocument).

Calling Called

CNG

ANSam

CM

JMCJ

Hang up

0-70.wmf



Error Code 0-74

NOTE: This error code can be generated by the calling terminalonly.

Because the calling terminal could not receive the first ANSam, orthe called terminal could not receive CM, the called terminal fellback to T.30 mode.

After detecting in the NSF or DIS signal that V.8 is enabled, thecalling terminal transmitted CI (Call Initiation) to restart the V.8sequence.

But, the called terminal could not detect CI signals, and finally thecalling terminal also fell back to T.30 mode.

CM, CJ and CI signals from the sender use V.21(L) modulation. Ifthe network cannot pass these signals, this problem could occur.

CNG

CI

DIS

ANSam

DCS

TCF

CI

DIS

ANSam

Calling Called

V.8 Available

V.8 AvailableT.30 Fallback

0-74.wmf



Error Code 0-75 (ANSam Timeout)

NOTE: This error code can be generated by thecalled terminal only.

The called terminal restarted the V.8 sequence afterreceiving a CI signal. However, it could not detect aresponse to ANSam within 3.2 s.

As a result, the called terminal then transmits NSFand DIS using T.30/V.17, signalling that V.8 isdisabled.

The receiver may have a problem detecting ANSam,or the network may have a problem transferringANSam.

9 August 2003

Protocol

CNG

CI

DIS

ANSam

DCS

TCF

DIS

ANSam

Calling Called

V.8 Available

V.8 Not Available

ANSam TimeoutT.30 Fallback

0-75.wmf

Page 757


Error Code 0-76 (CM Timeout)

NOTE: This error code can be generated by thecalling terminal only.

The calling terminal sent CM in response to ANSam,but it could not detect a JM within 3 s, so it fell backto V.17/T.30 mode.

The receiver may have a problem detecting CM, orthe network may have a problem transferring V.21(L)signals.

JM

CNG

CM

DIS

ANSam

DCS

TCF

Calling Called

V.8 Available

CM TimeoutT.30 Fallback

0-76.wmf



Error Code 0-77 (JM Timeout)

NOTE: This error code can be generated by the calledterminal only.

The called terminal sent JM in response to CM, but itcould not receive CJ within 3 s, so it fell back toV.17/T.30 mode.

JM

CNG

CM

DIS

ANSam

DCS

TCF

Calling Called

V.8 Not Available

JM TimeoutT.30 Fallback

0-77.wmf



Line Probing and Training

Error Code 0-80 (Phase 2 Timeout)

The line probing sequence was not completed within 35 s from the start of phase 2.

Error Code 0-81 (Phase 3 Timeout)

Equalizer training was not completed within 35 safter the start of phase 3.

In phase 3, if the rx level has almost reached the -20dBm threshold for ACG to switch on, the modemadjusts the gain control to amplify the signal.

But the resulting rx level may become too high forrx to continue. So, phase 3 cannot be completed,and the process goes back to the end of phase 2.

There is an A - B exchange, and the rx side sendsINFOh and goes back to phase 3. But the sameerror occurs again, and we are stuck in a loop. Aprotocol dump list shows repeated INFOh signals.Error code 0-81 prevents this repetitive cycle.

To solve the problem, the tx level at the sendershould be increased by 1 or 2 dB.

TX RX

INFO0c

1200 Hz

600 bps INFO0a

B

A

B bar

A bar

L1

L2

BA

INFOh

1200 Hz

2400 Hz

2400 Hz

2400 Hz1200 Hz

600 bps

600 bps

Spectrum

Spectrum

(Symbol Rate, etc.)



Control Channel Start-up/Restart

Error Code 0-82

The sender terminal could not start the control channel within 10 s, or the receiver terminal could notstart the control channel within 35 s.

A relatively low signal reception level or a high signal-to-noise ratio could cause this problem.

Normally, this occurs at the receiving terminal. If this occurred, check the reception level usingtechnical data print on the TCR/Journal, and ask the sender to adjust the signal transmission level.



Error Code 0-83

The sender terminal could not restart the control channel within 10 s, or the receiver terminalcould not restart the control channel within 11 to 35 s. The timer setting for Rx depends on thedata rate and data re-send status.

A relatively lower signal reception level or a high signal-to-noise ratio could cause this problem.

Normally, this occurs at the receiving terminal. If this occurred, check the reception level usingtechnical data print on the TCR/Journal, and ask the sender to adjust the signal transmissionlevel.

Error Code 0-84

The modem did not finish transmitting a signal within 10 s (during phase 4 – control channelstartup).

Try switching the machine off/on to reset the modem. Upgrading the modem's firmware may benecessary in some cases.

Error Code 0-85

The modem did not finish transmitting a signal within 10 s (during control channel restart).

Try switching the machine off/on to reset the modem. Upgrading the modem's firmware may benecessary in some cases.



Error Code 0-86

The other terminal specified a data rate that is not supported by the current symbol rate.

The other terminal is not behaving in accordance with V.8/V.34 standards.



Error Recovery using AC Tone

If one of the modems could not detect a response to thecontrol channel restart signals, it can send an AC tone toask the other modem restart the control channel. In theexample diagram, the tx side could not detect controlchannel signals, so it sends AC.

If the other modem detects an AC tone for more than 100ms, it responds with a PPh – ALT – MPh sequence evenin the control channel restart phase (normally, an Shsequence is used in the restart phase, not PPh).

If there is no PPh in response to the AC tone, the ACtone transmitter disconnects the line.

If AC tone is frequent to (or from) a certain terminal,adjust the transmission level or equalizer settings.

The AC tone may occur on noisy lines.

9 August 2003

Protocol

No response

TX RX

Sh

ALT

AC

ControlChannel

ALT

E

ControlChannel

Sh barSh

Sh bar

PPh

ALT

E

PPh

ALT

more than 100 ms

Co

ntr

ol c

ha

nn

el r

etr

ain

MPh

MPhMPh

MPh

AC TONE WMF

Page 764


Primary Channel

Error Code 0-87

NOTE: This error code is generated by the receivingterminal.

If the rx side cannot receive primary channel data (faxdata), it drops back into the control channel and waitsfor control channel signals (Sh or PPh) from thesender.

• This error could have been a temporary carrierdrop, for example.

When the control channel restarts, the rx siderequests all frames to be sent again in the PPRsignal.

Note that the rx side may receive all the framesproperly after this, but error code 0-87 is stillgenerated.

9 August 2003

Protocol

(Fax Data)

PrimaryChannel

Turn-off

Sh

ALTE ALT

E

Sh bar ShSh bar

Flag

PPR

PPS-Q

TX RX

1's

Flag

(Silence)

CFR

Flag

FlagFlag

No datareceived

Controlchannel

0-87.wmf

Page 765


Error Code 0-88

When nine PPRs have been sent back to the tx sidewithin the same ECM block, the line is disconnected.

PPS-Q means any of the PPS signals (such as PPS-EOP, PPS-MPS, and PPS-NULL). It is standardnotation for T.30 ECM protocol.

NOTE: Line disconnection after nine PPRs is aRicoh-specific function.

N eor = No. of PPRs before EOR is sent.

Fax data

PPS-Q

PPR

TX RX

Fax data

PPS-Q

PPR

Fax data

PPS-Q

PPR

Fax data

PPS-Q

PPR

EOR-Q

DCN

Neor Neor

DCN

9 (default)9 (default)

8

77

8

0 0

66

0-88.wmf


Group 3 Fax Communication Faxing From a PC

Faxing From a PC Fax Modems

Overview This section deals with boards installed in fax machines to allow a fax application package on a PC to send a fax through the fax machine to the telephone line. EIA/TIA (Electronic Industries Association/Telecommunications Industry Association) has two modem standards for PCs to interface with fax machines. These are known as Class 1 and Class 2. Class 1 is a bare-bones standard, providing just enough support to allow a PC to send a fax. Class 2 adds a wide range of modem commands based on the Hayes modem signaling standards. These commands are known as AT commands (AT is short for ‘Attention’).

AT Commands The AT commands that are implemented depend on the model.



Internet/LAN Fax Boards

Overview

What is an Internet fax? If a fax machine contains a network interface board and is connected to a LAN, the machine can send faxes over the Internet as well as using PSTN G3. This section explains how a fax machine can send fax messages to PCs and fax machines over a LAN or the Internet. An Internet fax machine is also known as a ‘NIC Fax’ or an ‘IFAX’. Using the Internet for faxing can reduce telephone line charges and paper consumption. The drawing outlines some of the network operations that a typical Internet fax can support (see the next page for an explanation).

G3 FaxMachine

011-1-212-555-3456#8888

PSTN

NIC Fax

03-3123-4567

Japan

[email protected] Printer

Server

Router

[email protected]@abcd.com

Internet

NIC Fax

nicfax@abcd. comPersonal Code 8888 = [email protected]

Ethernet

PaperPaper

Paper

PC display

RouterServer

Laser Printer

Ethernet

[email protected]

USA

[email protected]

H132V551.WMF



The NIC Fax at [email protected] can send a G3 fax message to a G3 fax machine inside Japan (at the top of the diagram), by dialing a telephone number. The NIC Fax can also send a fax message over the Internet by specifying an e-mail address ([email protected]) instead of the telephone number. The NIC fax can also send the message to a PC ([email protected]). Depending on the type of protocol used for reception, the received message will be either: Stored in the network server at the remote end, until the PC picks it up (this is reception using POP or IMAP)

Sent to the destination directly without being stored in a server at the receiving end (this is reception using SMTP)

How is it done? Protocol and Standards IETF (Internet Engineering Task Force) and ITU-T have standardized procedures for sending fax messages over the Internet as e-mail attachments. The message is sent as a TIFF-F format image file attached to a MIME format e-mail message. (Some older models can also send DCX image files, depending on a user setting). To receive a fax by e-mail, a MIME-compatible mail reader is needed. To view the fax, a TIFF-F viewer is needed. (For some models, the viewer should also be able to view DCX files.) The NIC fax must be connected to a LAN and set up correctly in order to use Internet fax functions. There is no need to set up a special server. Existing servers on the LAN can be used. TCP/IP



protocol is used. There must be an SMTP server to send mail, and either a POP3, IMAP4, or DNS server to receive mail. For people that do not have servers, the H535 model has an optional PDU unit that allows the mail transmission and reception to be done using servers at the Internet Service Provider. Software installed on the PC (such as a Web Browser) can be used to check the settings and status of a NIC fax from a PC.

Limitations An Internet fax does not contact the other party directly when sending a fax by e-mail. It only communicates with the local server, which passes the message through the network to a server at the other end, and the remote terminal picks it up from the server.

Except for errors during SMTP procedures, information about errors during e-mail communication will not be fed back to the sending Internet fax. Users have to confirm with the other end that important messages have got through.

Users are recommended not to send confidential material over the Internet. The level of security for Internet communications is low.

The Internet can get congested at times. If the message is time sensitive, use PSTN G3.

Voice communications are not supported over a LAN.

The next few sections explain in outline what functions are available with an Internet fax. They will be explained in more detail after sections describing some basics concerning e-mail and networks.



LAN Fax

The PC can use a fax application send a G3 fax message to G3 and Internet destinations through the Internet fax (also known as a NIC fax). Internet transmission is not shown in the diagram, but it can be done.

G3 FaxMachine

G3 Fax Message

PSTN

NIC Fax

[email protected]

PC to Fax Machine

NIC FaxServer

Laser Printer

PC FaxApplication

G3

Fax

Mes

sage

H132V552.WMF



The NIC fax will then send the fax message to the destination, which could be either a PSTN G3 fax or an e-mail address. Points to note about this feature are: • When sending a fax using the Internet, the receiving party can be another Internet fax or a

computer. The user inputs an e-mail address as the destination instead of a telephone number. • Received faxes can be sent directly to a PC by e-mail. • Fax messages can be sent from any PC (by e-mail or by Group 3 PSTN) on the same network as

the fax machine. (The machine is like a shared fax modem, with G3 PSTN and Internet capability.) • No paper is required at the transmitting side. • Software required on the PC depends on the model



IP Fax

This feature allows you use TCP/IP to communicate with fax machines. The other party can be on the same TCP/IP network as your machine, or it can be on the Internet anywhere in the world. • It can also be on a PSTN, if your intranet has a Gateway to interface with the PSTN. No e-mail server is required (compare with internet fax). Use the IP address (or host name) to dial the destination machine, instead of the fax number. • If there is a Gatekeeper on your intranet, you can use the ‘alias number’ stored in the gatekeeper.

The gatekeeper stores a look up table of ‘alias fax numbers’ and actual IP addresses.



Autorouting

The NIC fax routes incoming fax messages to client PCs on the same network, using the code included in the SUB signal.

G3 FaxMachine

PSTN

NIC FaxSUB Code:

5555

Fax Machineto PC

NIC Fax Server

Laser Printer

[email protected]

Personal Code 8888 = [email protected]

Personal Code 5555 = [email protected]

[email protected] Code:

8888

G3

Fax

Mes

sage

G3 Fax Message

H132V555.WMF



1. The sender must specify a code when sending a fax message. This code is transmitted using the SUB protocol signal (see ‘Protocol’ for more details on this signal).

2. Personal codes must be stored in the receiving NIC fax in advance, and associated with e-mail addresses on the same LAN. To do this, the machine uses the SUB code that is received, and the ‘Personal Box’ and ‘Transfer Box’ features. Personal Box: If the code in the received SUB signal specifies a Personal Box, the NIC fax routes the incoming message to the address that is stored with that Personal Box. Example: In the above diagram, if a received message has a SUB code of 5555, it is forwarded to [email protected] Transfer Box: If the code in the received SUB signal specifies a Transfer Box, the NIC fax routes the incoming message to all the addresses that are stored with that Transfer Box.

3. The client PC receives the fax as an e-mail message with an image file attached. If a machine cannot send a SUB code, the Forwarding feature must be used for that machine (this is the next feature to be described). Advantages of this are: • Fax messages are delivered directly to the mail server for the client PC to pick up. • No paper is used.



Forwarding

The NIC fax routes incoming fax messages to client PCs on the same network, based on the contents of the RTI or TSI. In this way, a message from a certain sender can always be forwarded to a certain location.

G3 FaxMachine

PSTN

RTI: FREDFax Machine

to PC

NIC Fax Server

Laser Printer

[email protected]

Forwarding by TSI: For 1234, send to [email protected] by RTI: For FRED, send to [email protected]

[email protected]

TSI: 1234

G3 FaxMachine

H132V556.WMF



1. The sender must have a TSI or RTI programmed.

2. RTIs and TSIs of expected senders must be stored in the receiving NIC fax in advance, and associated with e-mail addresses on the same LAN. If the received RTI or TSI is the same as one of those stored, the NIC fax routes the incoming message to the associated address. Example: In the above diagram, if a received message has an RTI of FRED, it is forwarded to [email protected]

3. The client PC receives the fax as an e-mail message with an image file attached. Advantages of this are: • No SUB code is required for forwarding (some machines cannot send SUB codes). • Fax messages are delivered directly to the mail server for the client PC to pick up. • No paper is used.



Internet Fax (Paper to Paper)

1. Instead of a PSTN telephone number, an e-mail address is specified when sending a fax message.

2. The fax message goes through the Internet to the receiver, and is printed.

NIC Fax

Japan

Laser PrinterServer

Router

Internet

Router

NIC FaxServer

Laser Printer

Ethernet

Ethernet

USA

To: [email protected]

[email protected]

H132V557.WMF



NOTE: The time required to send a fax over the Internet depends on the traffic conditions at the time of transmission. Also, the sending machine has no way to know whether the message arrived intact at the other end.

The advantage of this is that it is cost-saving.



Internet Fax (Paper to PC)

1. An e-mail address is specified when sending a fax message. 2. An e-mail message is sent to the client PC with the fax message attached.

NIC Fax

Japan

Laser PrinterServer

Router

Internet

Router

NIC Fax

ServerLaser Printer

Ethernet

Ethernet

USA

To: [email protected]

[email protected]

[email protected]

H132V558.WMF



The PC must have: • E-mail software to pick up the e-mail from the server • A TIFF-F or DCX file viewer to read the image The advantages of this are: • Cost-saving • No paper is used



Transfer Request through the Internet

G3 Fax Machine

NIC Fax

Japan

Laser PrinterServer

Router

Internet

RouterNIC Fax(Transfer Station) Server

Laser Printer

Ethernet

Ethernet

USA

To: Quick Dial 01 stored [email protected] [email protected]

206-936-1234

PSTN

Quick dial #01= 206-936-1234

H132V559.WMF



A fax message can be transferred over the Internet and then forwarded to a G3 facsimile, using the NIC fax as a transfer station. 1. The sender specifies the end receivers using the quick dials, speed dials, and group dials that

are stored in the transfer station. 2. The fax message is sent to the transfer station over the Internet and the LAN at the remote

location. Then it is transferred to the destination over the local PSTN. It can also be transferred by e-mail over a LAN or the internet, if the transfer station is a NIC fax.

This saves costs for long-distance communications.



LAN Basics Before we look at Internet fax features in more detail, it is important to know a bit about Local Area Networks (LANs) and e-mail. This section will deal with LANs, and the following section will deal with e-mail.

LAN Configurations

Overview

A LAN (Local Area Network) links computers within an installation such as a building or factory. It consists of communications hardware such as interface boards and cables, and software for the computers that are to be connected.

Basic Types

The following three configurations are available for linking computers. The different wiring configurations are often referred to as ‘topologies With all three topologies, signals sent from one computer go to all other computers. An address is included at the start of the data so that it is ignored by all computers except the destination.



Bus Configuration

One central cable is installed, with computers connected to it in branch fashion. All data is sent via the central cable. a) Bus Connection

H132X501.WMF

Network Topology



Star Configuration

A central hub is used, with computers connected around it. All data is sent from the central hub.

b) Star Connection

H132X502.WMF



Ring Configuration

Computers are connected in a ring. Because the data sent by one computer reaches all the others, only one computer may send data at any one time, or there will be a collision of data on the circuit. If one computer continues sending data, it will occupy the LAN to the exclusion of all others. To prevent this problem, data is limited to a length of a few kbytes. These small units of data are referred to as ‘packets’ or 'frames'.

c) Ring Connection

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Avoiding Data Collision Collisions occur when data is sent from a number of computers simultaneously. Two methods are employed to prevent this. (a) The computers detect whether there is any data on the LAN, and only send when the LAN is free.

There are several ways to do this. A typical method is CSMA/CD, which is used with Ethernet applications. CSMA/CD (Carrier Sensing Multiple Access/Collision Detection) A method by which multiple computers have access to the transmission route (referred to as ‘multiple access’). The computers monitor the transmission route for data (carrier sensing), and send data if none is currently being sent. If a data collision is detected, the data is resent after a randomly determined wait time.

(b) Token passing, in which collision of data is avoided before the event. Tokens ensure that the data only goes to the intended computer.

The various connection configurations and ways of avoiding data collision have resulted in a number of different types of LANs. The different types are incompatible when directly connected to each other, thus requiring the use of relay devices.



Main LAN Types and Their Characteristics

Type Cable

connection configuration

Transmission speed Cables

Access control

(collision avoidance)

Remarks

10Base-5 Bus 10 Mbits/s Thick coaxial CSMA/CD The original Ethernet configuration

10Base-2 Bus 10 Mbits/s Thin coaxial CSMA/CD A simplified version of 10Base-5

Ethernet

10Base-T Star 10 Mbits/s Twisted-pair CSMA/CD Currently the main type in use

Token ring Star 4 Mbits/s or 16 Mbits/s Twisted-pair Token passing IBM standard

LAN

FDDI Ring and star 100 Mbits/s Optical fiber, twisted-pair

Token appending

Used primarily for trunk lines

Local Talk Daisy chain 230 kbits/s Twisted-pair Proprietary Fitted as standard to Macintosh PCs

* The NIC fax uses 10Base-T.



Ethernet

Overview

Ethernet is currently the commonly-used LAN. It was originally developed by DEC, Intel, and Xerox. The original Ethernet standard incorporated what is now known as the 10Base-5 specialized Ethernet coaxial cable. The IEEE802.2 standard was based on the Ethernet standard. Specifications for hardware components such as cables, were revised. IEEE802.3 was then developed for use with media other than 10Base-5. 10Base-2, 10Base-F, and the most widely used 10Base-T, were subsequently developed. In contrast to the Ethernet standard data transfer speed of 10 Mbps, IEEE802.3 allows data transfer at speeds between 1 and 20 Mbps.



Ethernet Frame Structure

Ethernet frames consist of the addresses of the source and destination computers, an identifier for the type of protocol used, the data, and finally the FCS (which is used to check whether or not the data has been correctly sent and received). Compare the Ethernet frame type and the IEEE802.3 frame type in the following diagram.

Data (46 ~ 1,500 octets)Ethernet frame

Frame Type (2 octets)Source Address (6 octets)

Destination Address (6 octets)FCS (4 octets)

LLC Frame(Data, 46 ~ 1,500 octets)IEEE802.3 frame

LLC Data Length (2 octets)Source Address (6 octets)

Destination Address (6 octets)FCS (4 octets)

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• FCS (Frame Check Sequence): A CRC (Cyclic Redundancy Check) is employed to check whether or not the received data is correct. The receiving device (receiving node) reconstitutes the FCS from the received data. If it does not match the sent FCS, that frame is discarded as corrupted.

• Identifier: Indicates the type of data that follows. The identifier is referenced by the receiving node to determine the type of protocol used to send the data.

• Octet: A unit employed to indicate network data size. 1 octet is 8 bits (1 byte). The term is used to make a clear division into 8-bit units from a continuous stream of 1s and 0s with no inherent division into bytes.

• LLC (Logical Link Control): The name of the data frame defined in IEEE802.3.

• Node A computer or printer connected to the network.



MAC Addresses

To allow each node in the network to communicate with others, it must have a unique identifier. In the Ethernet standard, a 48-bit address known as the MAC (Media Access Control) address is assigned to each computer. Each data frame contains the MAC addresses of the source and destination computers. The MAC address is a fixed physical address that is set on the network card. It is six bytes in length for the Ethernet standard. The first three bytes are a header code which is controlled and allocated by the IEEE, and the last three bytes are a code independently controlled with each header (to prevent duplication). This ensures that the physical address of each Ethernet card is unique. Under the Ethernet standard, frames are sent and received using these addresses (see ‘Ethernet Frame Structure’).



LAN Hardware

Overview

The basic LAN configuration consists of four hardware items. • Interface boards - also known as LAN boards or Network Interface Cards (NICs):

Convert digital data into electrical signals, prevent data collision, and transmit data on cables • Cables:

Primarily unshielded twisted-pair (UTP) and optical fiber cables • Hubs:

Distribute signals • Relay devices:

Connect LANs for the transmission of data to remote locations LAN devices are regulated by IEEE (Institute of Electrical and Electronic Engineers) standards. In addition to hardware, the following types of software are also needed. • Transmission protocol software that can transmit data via a variety of relay devices • Applications (database, e-mail), to provide the data in a format usable by the operator



Relay Devices

Relay devices are required to expand LANs. These devices do the following. Extending the Connection Distance

LANs allow high-speed transmission of data, achieved by sending high frequency signals over the cables. High frequency signals are considerably attenuated when transmitted over the cables, and signal waveforms are easily distorted, resulting in difficulties when transmitting over long distances (the maximum distance for transmission using twisted-pair cables to connect the hub and terminals with 10Base-T is 100m). When expanding a LAN, relay devices are used to amplify the attenuated signals. Distorted signals are first converted back to digital format and regenerated to remove the distortion. To cover even more remote locations, telecommunications companies provide dedicated lines, PSTN lines, and ISDN lines for connection to remote LANs.



Connection between Networks of Different Standards

As the types of cable used, and the signal and data format differ between different LAN systems, such systems cannot be connected directly. When a LAN system has to be connected to a different system, a relay device that can convert between the two systems is employed. Conversion between different LAN systems involves first converting the signals back to digital format, and resending them in a format appropriate for the destination LAN. Control of High-speed Transmission Routes

As the network grows, the number of connected computers increases, and so does the volume of data transmitted. There is a limit to the amount of data that can be transmitted on the network. When this is exceeded, the flow of data is impeded and communications are no longer possible. There are a number of ways to increase the speed of data transmission on a LAN. A high-speed LAN may be used to prevent network congestion when the amount of data to be transmitted is large. When connecting LANs of different transmission speeds, relay devices are required that can convert between the two LAN types. By-pass circuits may be installed when connecting LANs with relay devices. When there is a complex web-like interconnection of networks, there are a number of routes to the destination, so that busy parts of the network can be by-passed.



Filtering

There are also relay devices that can check the data on the network and remove all except that which is necessary. This is referred to as 'filtering'. Controls which pass only specific protocols (used for the transmission of data and voice between terminals on networks such as TCP/IP, IPX/SPX, AppleTalk) are used to alleviate congestion in the relay circuits. As the number of users increases, the network is used for greater variety of purposes, resulting in the entry of data through illegal access. Relay devices to limit access and to maintain security become necessary.



Types of Relay Devices and Gateways Relay devices may be of various types - repeaters, bridges, switches, routers - depending upon their purpose and principles of operation.

Types of Relay Devices and their Functions

Function Repeater Bridge Switch Router Cable extension Connection with remote sites Connection with different LAN types Avoiding congestion Restricting access



Repeaters

A repeater amplifies signals. It is normally connected to a number of LANs, and amplifies signals from one LAN (one segment) and outputs it to another LAN (another segment). It is considerably cheaper than a bridge or router, and does not require special setup. After power is switched on, the repeater connects to the two networks. As distortion occurs when signals are amplified, the number of repeaters is limited to two with Ethernet. Repeaters have no ability to store data, and are unable to prevent collisions when sending signals. Therefore, they have no effect on relieving congestion in a network.

Amplifies the signal

Signal

Becomesweaker

LAN

Repeater

LAN

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Bridges

In the same way as a repeater, a bridge converts received electrical signals back to digital format, and then regenerates the original electrical signals for transmission, thus preventing signal distortion. Bridges can also filter out unnecessary data, and can act to alleviate congestion on the network. The bridge records the source MAC address in the header of the arriving data packets. In this way, the bridge builds up a picture of the location of each node (PC and printer). In the example shown below, data sent from A to B also reaches the bridge. The bridge automatically records this data and remembers that A is located in the left-hand segment. When data is subsequently sent from B to A the bridge does not relay it to the right-hand segment. This process is referred to as filtering. The bridge does not require special setup. After power is switched on, the bridge connects to the two networks. Signals to node B are not

transferred to the right-hand side.

Left Side Right SideA CB

Bridge

Signals to node C are transferredto the right-hand side.

A B C

A CA → C

A BA → B

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Switches Switches have the same filtering function as bridges, however they also support simultaneous connection of multiple LANs, and allow parallel relaying. Relay processing time is reduced in comparison to bridges, and operation is therefore faster.

Switch

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Routers

A router checks the destination information in the headers of the data packets on the network and determines which LAN it has to be sent to. The router contains a table which records the destinations.

A

B C

D

E

Router

Router

Router

Router

Up

RightLeft

RightLeft

A

CB

DE

Data going to LAN segment A is transferred to the upper route.Data going to LAN segments B or E is transferred to the left-hand route.Data going to LAN segments C or D is transferred to the right-hand route.

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In contrast to repeaters and bridges, simply switching power on and connecting to the networks does not make ready the router for operation. Software appropriate for the communications protocol must first be installed, the network configuration checked, and the setup completed. While filtering with bridges is implemented primarily by the checking of addresses, filtering with a router is implemented by the communications protocol. Depending upon the application protocol, the router may be set to pass e-mail data, but not to transfer files. Routers support considerably more sophisticated functions than bridges. For example, they may be set up to allow high priority data to be passed more quickly (priority control). Different LAN types have different formats for the destinations. The router makes sure that the destination is in the correct format for the next network. When there are multiple routes to the destination, bridges and switches cannot be employed to reduce congestion since the data is sent via all routes. Routers, on the other hand, employ a number of routes set beforehand in accordance with the amount of data to distribute the load throughout the network (while bridges divide up the network with MAC addresses, routers achieve this, in the case of a TCP/IP protocol, by analyzing IP addresses and sub-nets). The router is a device central to the configuration of the network, and as such router functions are implemented in software in PC LAN servers and UNIX machines.



NOTE: In the NIC fax, the device setting the IP address as the default gateway is in practice a default router. When data is sent from the network belonging to the local machine to other networks, the device at the exit from the network is referred to as the default router.

Gateways

While repeaters, bridges, and routers are available as dedicated hardware for network use, gateways are available as server and client software packages. They analyze all network communications protocols, and convert data, thus allowing connection of different networks. The Netware Gateway Service supplied with the Windows NT Server is an example of this software.



Network Protocols

Overview

Network protocols are standard procedures for transmitting data over a network. There are different protocols for different stages of the communication.

Data Transmission

Data is sent using the following procedures. (1) Finding the destination (2) Determining the route to the destination (3) Sending the data

A number of protocols must be used in combination in order to execute each procedure. The TCP/IP protocol used with the Internet, the Netware IPX/SPX protocol, and the Macintosh AppleTalk protocol, are combinations of protocols designed to achieve various specific procedures. Protocols used for steps (1), (2), and (3) listed above are referred to as (1) the name service protocol, (2) the routing protocol, and (3) the transfer protocol respectively.



The roles of the protocols

Network

Target PC

Transfer protocol

Name ServerDirectory Server

Router

Routing protocol

Name service protocol

Sending PC

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Name Service Protocol

A computer name is normally assigned to the computer. However, for the purposes of transmitting data, the name is converted to an address indicating its location on the network. The name service protocol provides lists of all names when the destination computer name is unknown. The address is an identifier used in distinguishing between terminals and nodes on the network. The most common addresses are IP addresses and MAC addresses. An IP address consists of a network address (to identify the network to which the terminal belongs) and a host address (to identify the terminal within the same network), both of which are set by the user. A MAC address is registered in the memory of the network interface board by the manufacturer. Each MAC address is unique (no two are alike throughout the world).

Routing Protocol

The routing protocol is used in determining the route used to transmit the data. A preset network route may be necessary, or it may be determined automatically by communication between routers. If relay devices are to be added or moved, it is convenient to have a method of automatically determining new routes. The routing protocol provides this ability.



Transfer Protocol

The transfer protocol is used in the transmission of data. It first checks for errors in the received data, and resends it if an error is detected. It also controls the rate at which data is transmitted, by communication between the source and destination. In addition to these basic protocols, there are also various other protocols which provide for notification of network congestion, notification of errors, and so on.



Protocols Used with Different LAN Types

Name Service Protocol

Routing Protocol

Transfer Protocol

Protocols used with the Internet (TCP/IP) DNS RIP

OSPF

IP TCP UDP

Protocols used with Netware (IPX/SPX)

SAP NDS

RIP NLSP

IPX SPX

Protocols used with Macintosh (AppleTalk)

NBP ZIP RTMP DDP

ASP

DNS: Domain Name Service NLSP: NetWare Link State Protocol RIP: Routing Information Protocol IPX: Internetwork Packet Exchange OSPF: Open Shortest Path First SPX: Sequenced Packet Exchange IP: Internet Protocol NBP: Name Binding Protocol TCP: Transmission Control Protocol ZIP: Zone Information Protocol UDP: User Datagram Protocol RTMP: Routing Table Maintenance Protocol SAP: Service Advertisement Protocol DDP: Datagram Delivery Protocol NDS: NetWare Directory Service ASP: AppleTalk Session Protocol



TCP/IP

Overview

TCP/IP is the standard Internet protocol, and is supported as a standard by Windows 95. It allocates 32-bit network addresses (IP addresses) to the nodes. As the addressing system does not depend upon physical media, TCP/IP provides for considerable flexibility in selection of routes. The use of TCP/IP is not limited to Ethernet, but allows use of a variety of physical media. TCP/IP is a combination of the TCP protocol and IP protocol.

Communications with IP protocol

The IP protocol divides data into packets. When the destinations may be on several different LANs, the router selects the appropriate route for each packet before it is sent. This process is repeated until all data arrives at the destination network.



IP Address

Communications with IP protocol requires that network devices such as PCs and routers using TCP/IP be assigned a 32-bit IP address as a means of identification. When used in a single closed network, the IP addresses (referred to as private addresses in this case) may be used freely. However, when connected to the Internet, global addresses which are unique throughout the world must be used. Global addresses are managed by the Internet Assigned Numbers Authority (IANA), and are assigned upon receipt of an IP address.

IP Address Format

IP addresses are 32 bits in length, and are normally converted to decimal notation in four 8-bit blocks as shown below.

Example of IP Address Notation 133. 139. 212. 11 Host portion (16 bits) Network portion (16 bits)

The IP address consists of host and network blocks as shown above. The network block represents a logical collection of hosts (a network), and the host block specifies a unique host within the network.



In the example above, a maximum of 65,534 (the maximum number of combinations of 16 bits) hosts may be allocated to that particular network block. As TCP/IP involves the routing of packets using the address in this network block, the network block must be unique (no two can be alike throughout the world). On the other hand, the address within the host block is up to the user.

Subnet and Subnet Masks

Subnet masks divide the host block into sub-nets. In the example above, there are 65,534 possible host addresses, and it is difficult to manage all with one network. The host address block is therefore subdivided into the upper and lower 8 bits, with the upper 8 bits handled as a logical group address. In this way, the IP addresses assigned to a company for its networks can be divided up into sub-nets of about 250 hosts for ease of management (each department of the company can be allocated a different logical group number, for example).

Example: Sub-net 133. 139. 212. 11 1 ~ 254 ... 254 hosts Logical group Host block (8-bit)



The final part of the IP address (the host block) cannot be 0 or 255. The dividing is done using a parameter known as the subnet mask. The subnet mask blocks off addresses, only permitting certain addresses to be used in a subnet. A logical AND operation is done using the subnet mask to find the range of allowed sub-net addresses. If your computer has the IP address 210.145.159.11, and the subnet mask is 255.255.255.0, the server can recognize that machines with an IP address of 210.145.159.* are on the same LAN, so messages are sent to it directly. Any IP address with a different value at the start has to be accessed through a router. The following diagram shows how the AND operation can be used to limit the size of the subnet to a few IP addresses.



1

IP address and Subnet maskIP Address (4 octets)

1 0 0 1 0 0 1 1 0 0 1 0 0 0 1 1 0 0 1 1 1 1 1 0 0 0 0 1 0 1 1

210 145 159 11

1

Subnet mask

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0

255 255 255 240

28 bits

14 hosts are available

The address "0000" and "1111" cannot be used

Logical Network Address

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TCP and UDP

While data is formatted into packets and sent to the desired node on the Internet using IP, communications applications (eg e-mail) do not control data transmission in packets. The host requires a procedure for passing IP packets to the desired application. This requirement is satisfied with TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).



E-Mail Basics

Principles

Overview

Electronic mail (E-mail) is a system by which messages in the form of digital data are sent and received between computers. A variety of types of electronic mail are available - Internet e-mail, Microsoft Mail as used with the exchange client under Windows95, and Lotus Notes Mail. E-mail works as follows. • Messages are stored at some location. • Users generally have equal privileges, and are able to both send and receive messages. A telephone system requires that users are able talk to each other simultaneously. In the case of e-mail, the user first receives the message, and may then read it at any time, and send a reply if necessary.



Sending And Receiving

E-mail generally supports the following functions. • A UA (User Agent) for creating e-mail and displaying received mail. • An MTA (Message Transfer Agent) to handle transfer of messages. The mail created by the sending UA is sent from the sending MTA to the receiving MTA, and displayed by the receiving UA.

The simplest e-mail system is one in which messages are stored at a location accessible by all users. Each user has his/her own mailbox, and the sender puts messages in the recipient’s mailbox. The recipient checks his/her mailbox to receive mail.

User Agent Message Transfer Agent

User AgentMessage Transfer Agent

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The mailboxes are normally at one location, often referred to as a “post office”, and the process of sending e-mail approximates that of sending mail at the post office. When the post office is accessible from all computers connected to the network, the system constitutes an e-mail system. Microsoft Mail as used in Windows95, and Lotus Cc: Mail employ this system, as does the UNIX local mail system (i.e., not connected to the Internet, etc.).

E-Mail Networks

As the number of users increases, and geographically distant users are connected to the network, multiple post offices must be established, and users are no longer able to use the same post office for sending and receiving mail. A system which connects post offices for the purpose of exchanging mail (a transfer system) then becomes necessary. In this case, the destination of mail is checked at the post office, separated into the various destination post offices, and passed it to the transfer system. The transfer system then communicates with the transfer systems of other post offices, and transfers the mail to the appropriate post offices. Mail sent from other post offices is sorted into the appropriate mailboxes at the receiving post office. The above is a general description of an e-mail system. These functions are implemented with the exchange server software packages for Microsoft Mail and CC: Mail using optional gateway software. The fundamental principles of Internet mail are the same, and are implemented in the UNIX SendMail program under UNIX.



The following diagram shows what happens when somebody sends mail from a PC to a receiver with an account in the same post office and to a receiver with an account in another post office. Machines A and B both have accounts in mail server 1. Machine C has an account in mail server 2. When machine A sends the message, it goes to the local mail server using SMTP protocol. SMTP is based on TCP/IP. The post office transfers the message to receiver B’s mail box. Receiver B picks the mail up from there, using POP procedures (POP is also based on TCP/IP). To get to receiver C, the server sends the mail to mail server 2, using SMTP procedures. Mail server 2 puts the incoming mail into receiver C’s mail box. Receiver C picks it up using POP procedures. SMTP and POP are both procedures for Internet mail based on TCP/IP. If there is no SMTP server on the LAN, the fax machine cannot send e-mail. If there is no POP server on the LAN,

Sender AClient mail software

Mail server 1

Mail server 2

SMTPProcedures

SMTPProcedures

Receiver BClient mail software

POPProcedures

POPProcedures

Receiver CClient mail software

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the fax machine cannot receive e-mail. Some more detail on SMTP and POP follow later in this section.



Internet Mail

Overview

Internet e-mail (hereafter referred to as Internet mail) is a system for creating text messages in accordance with a set of standards, the messages then being sent to destinations using SMTP (Simple Mail Transfer Protocol). NOTE: SMTP is a protocol for sending and receiving mail as defined in RFC821. It was originally

developed for sending and receiving mail between servers. However it is currently used for sending mail from client environments using POP (Post Office Protocol – discussed in a separate section).

Character Codes

Messages consist of a header and the main text, both being subject to restrictions on usable character codes. Specifications for data exchanged on the Internet are determined within the organization of the Internet, and do not necessarily conform to ISO (International Standards Organization) requirements. However, these organizations have codified these specifications to the extent that they are now the default standards organizations. For example, the main text of a message created Japanese using JIS character codes must satisfy a particular set of requirements for transmission on the Internet. However, if it is to be sent on a



network within a particular company, the unique requirements of that system may mean that the JIS codes are not always used.

Message Address Notation

The UA attaches the required header to the main text and sends it to the MTA. The MTA then adds to or changes the header as required to ensure that the message transfer route is recorded, and that the addresses of the destination and sender are correct. Internet mail employs an 'address' to specify the message destination. The address format is generally as follows.

user name @ domain name

The mailbox name is generally employed as the ‘user name’. The MTA uses the ‘domain name’ to check the destination IP address with the DNS, and then sends the mail using SMTP. NOTE: DNS (Domain Name System) is a service which enables the IP address to be obtained from

the host name under the TCP/IP network environment.



DNS and Domains

The IP address allows destinations within the Internet to be identified. This IP address is, however, a string of numbers not easily remembered by the user. To resolve this problem, a corresponding name is added so that the user need only specify the name in order to identify the destination. DNS was developed for this purpose. Internet domain names are distributed among organizations in a hierarchical manner, with lower order domains being managed by the higher order domain. All organizations participating in the Internet have a domain name. The domain name first identifies countries, and is subsequently further divided in a tree structure to identify organizations. The name server (DNS server) located in each domain holds the information about the domains and hosts under its management. When the client communicates using a host name or domain name, an inquiry is made to the DNS to obtain the destination IP address. Note that this domain name structure is independent of the physical structure of the network. The items in brackets below are examples of domain and mail addresses.

DNS model

host-2

a a a

c c c

e e e

d d db b b

g g gf f f

host-1 host-3

(jp domain)

➀➀➀➀

➁➁➁➁

➂➂➂➂

(co domain)

(ricoh domain)

host-2.eee.ccc.aaa(f64g@ricoh. co. jp)

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Internet Fax and DNS

A NIC fax can use the Domain Names for the SMTP and POP3/IMAP4 server instead of the actual IP addresses, if there is a DNS server on the same LAN as the SMTP server, POP3/IMAP4 server, and the NIC fax. If the NIC fax does not support DNS, the user must input the actual IP addresses of the SMTP and POP3/IMAP4 servers.

Transfer Of Incoming Mail

In some cases, incoming mail may be transferred to another server using SMTP and then stored on another mail server. The UA used by the user receiving this mail detects its arrival (e.g., by monitoring the contents of the directory designated to contain mail) and informs the user. The UA then extracts the mail in accordance with instructions from the user and displays it. The mail stored on the server is transferred to the user's PC using POP.

E-mail transration

DNS

MTA

DNS

MTA

MTASMTPSMTP

➀➀➀➀

➁➁➁➁

➂➂➂➂➃➃➃➃

name@aaa. ccc. ddd

user name domain name



The mail address consists of a host name (mailbox name) and domain name. Mail is distributed by first finding the IP address of the destination with the DNS, and then transferring the message using SMTP.

1. The mail destination within the relevant domain is checked using the domain portion of the mail address.

2. The MTA then connects to the destination mail server using the mail address thus obtained. 3. The mail is transferred to the destination MTA using SMTP. 4. Depending upon the size of the organization, the message may be further transferred to an

internal MTA (not visible from outside the domain). NOTE: POP (Post Office Protocol) is a protocol used to read the content of the mail spooler using

TCP/IP protocol. It is specified in RFC1725 (see a later section for more details). Verifying Incoming Mail

Arrival of mail at the intended destination on the Internet is not guaranteed. In the worst case, it may disappear at some unknown location. Furthermore, it is impossible to verify whether sent mail has been read or not. Mail sent on the Internet passes through multiple servers and networks, and computers used within the Internet are of a variety of architectures. The network therefore contains a wide variety of hardware environments, in addition to the wide variety of software employed for mail transfer. While there are no problems in most cases, it is obvious that arrival of mail cannot be completely guaranteed within this complex environment.



Message headers

Requests for Comments

The basic protocols used for transmission of messages on the Internet are defined in RFC822. RFC822 primarily defines the header information for e-mail, with the details of the main text of the message being defined in MIME (RFC2045 - 2047).

NOTE: 1) An RFC (Request For Comments) is a document formally released by the Internet Engineering Task Force (IETF). The IETF has released a wide variety of RFCs on technical matters (e.g., network protocols) related to the Internet environment.

2) MIME (Multipurpose Internet Mail Extensions) is a protocol which removed such restrictions as the number of characters per line, and the maximum size of an e-mail transmission. It also made possible the transmission of non-character data (e.g., programs and bitmaps).

Header Format The header of an e-mail message consists of a header and the main text. A blank line is inserted between this header and the main text (the blank line is not included in the header). The header is defined as a collection of fields, with the field format as follows.

field name ”:” content



An example of the ‘To’ field, indicating the destination, is as follows.

To:[email protected]

Header Example:

Received: from F64G.shinyoko.ricoh.co.jp ([133.139.167.30]) by bb.shinyoko.ricoh.co.jp (4.1/2.8Wb-91Jan07) id AA15193; Sun, 15 Feb 98 14:53:50 JST Return-Path: <[email protected]> Message-Id: <[email protected]> Date: 15 Feb 1998 14:54:06 +0900 X-Mailer: ICFAX Version 1.0 Mime-Version: 1.0 Content-Type: multipart/mixed; boundary = “--ICFAX_60670AE6CB--” To: [email protected] From: [email protected] Subject: Fax Message NO.0003 from “+81454771786” (“RICOH SERVICE”)



Header Types

While a number of header fields are possible, the following three must be present. • Date • From • To

Message Header Table (fields defined in RFC822)

Field Field name Meaning Description

Date Date Date that the mail was created

Date and time in specified format Syntax: <address>

Person submitting

mail From

Person submitting mail Mail address (including comments)Syntax: <address>

Sender Person sending mail Mail address (including comments)Syntax: <address>

Reply-To Destination when a reply is sent

Mail address (including comments)Syntax: <address>

To Mail destination Mail address (including comments)Syntax: <address>

Address

Cc Destination of carbon copy




Field Field name Meaning Description

Address Bcc Destination addressees not covered by To and CC


Message-Id Message ID Message identification In-Reply-To Source of reply Message ID of original mail References Referenced mail Message ID of referenced mail Reference

Keywords Keywords for search purposes

Any character string

Subject Mail title (summary) Any character string Comments Mail comment Any character string Other Encrypted Encryption algorithm

specification Defined word (defined in separate RFC)

Return-Path

Route for return of mail Mail address

Route Received

Transfer record added by MTA

Describes transfer destination, transfer source, and protocol etc with From, By, With, etc

User defined Fields defined by user Field names beginning with X-.

May be any character string, definition is up to the user.

* Other fields are available defined by separate RFCs (e.g., MIME).



Fields for Sending E-Mail

- From Field - The From field indicates the person sending the mail. The difference between the From and Sender fields is that between ‘the person creating the message’ and ‘the person actually sending the message’. These two fields are used when the two differ. When the From field is omitted, the Sender field is added automatically. When a error occurs, a error notification is sent to the destination in the Sender field. When the Sender field has been omitted, the notification is sent to the destination in the From field. Fields containing mail addresses may also include real names as a comment (the same applies to the Person Sending Mail and Addressee fields). In both cases below , ‘IC FAX’ is handled as a comment, and [email protected] is recognized as the address.

Example 1 From: IC FAX <[email protected]> Example 2 From: [email protected] (IC FAX)

Multiple mail addresses may be delineated by commas, and both address formats may be used together. - Reply-To Field - Reply-To clearly specifies the address to which the reply is to be sent. As this field may be omitted, it is possible that mail may be sent with this field blank. In such cases, the mail is returned to the address in the From field.



When both the From and Reply-To fields are used, the latter has priority. The Return-Path field appears to have a similar function at first glance. However it is not for return of mail, but is automatically added by the transfer system to specify the person submitting the mail, and is used to investigate the mail route when an error occurs.

Addressee Fields

- To Field - The To field specifies the addressee for the mail. As with the From field, multiple mail addresses may be delineated with commas. The To field differs from the Cc field in that only the name of the person sending the message is specified. - CC Field - Mail is sent to the addresses in the Cc (carbon copy) field in the same way as to the address in the To field. The difference only with the To field is whether the name is in the To field or the Cc field of the received mail. - BCC Field - Bcc means Blind Carbon Copy. The Bcc field is deleted in mail sent to the addressees in the To and Cc fields. It is most commonly used when the address of the person sending the mail (the user in the From field) is to be entered in order to leave a copy of the sent mail. As some mail software saves a copy of the sent mail, it may not be possible to specify the Bcc field in some cases.



Exceptions

The addressee fields do not always contain the addressee’s name when mail is received. This is because since the actual addressee for the mail is specified by the MTA, when an alias is used to create a virtual addressee (in a local system, for example), the virtual address remains in the To field. This also occurs in cases such as mailing lists in which mail is sent to all on the mailing list.

NOTE: 1) An alias is a group address. Mail sent to the group address is sent to all members in the group.

2) A mailing list is a form of electronic conference using e-mail. E-mail sent to a mailing list is transferred to each member of the list. As such, it provides the same service as available with a PC-based centralized host-type bulletin board system in a distributed network environment.

Date

The Date field indicates the date on which the mail was created (not the date it was sent). The date is in the following format.

Day, date month year hour: minute: second zone

Zone indicates the local time used in the system in which the mail was created, and is expressed as GMT+/-hhmm.



Miscellaneous

- Received Field - The Received field is used by the MTA sending the mail, to record the status of the mail. This field shows the route over which the mail was sent, and the computers which handled it prior to delivery. In addition to information showing when and where the mail originated, and where it was sent to, some systems add further information (e.g., host IP address, software version) as a comment. - Message-ID Field - Internet mail adds an internationally unique message ID. This ID is created automatically, and is normally a combination of the time the message was sent and the name of the mail server.



SMTP

Overview

SMTP (Simple Mail Transfer Protocol) is used as the protocol for communication between Internet mail MTAs. It is defined in RFC821, which covers 8-bit data communications and message size negotiation, etc. SMTP is expanded upon in RFC1651 and RFC1653 as ESMTP. SMTP uses text-based commands and responses between the client and server. In practice, it is a protocol used under TCP/IP, and data is therefore sent and received under TCP. Retry processing with communications errors is therefore handled at the TCP/IP level, and SMTP therefore needs only to handle sending and receiving of data, and command errors.



SMTP Commands

SMTP commands are sent, and responses received, between the client and server when sending Internet mail. This communication involves sending of the domain name, sender's name, destination name, and main text etc to the server, and user verification.

Sender AClient mail software

Mail server 1

Mail server 2

SMTPProcedures

SMTPProcedures

Receiver BClient mail software

POPProcedures

POPProcedures

Receiver CClient mail software



POP

Overview

E-mail on the Internet was originally transferred between hosts using SMTP, with the computer receiving the mail being operated all day long under the control of SMTP. In practice, the use of dial-up IP connections to connect to the mail server via telephone lines, and the fact that the power supply may be switched off when the user returns home in the case of PC clients, means that mail cannot be transferred until the user connects to the server. POP (Post Office Protocol) servers are used in such cases, i.e., when the connection is not permanently established.

Pop Server Configuration

The POP server is a computer which receives user mail using SMTP. The mail for the user includes a setting to ensure that it is directed to the POP server. Following connection to the Internet, the user receives e-mail directed to the server with POP procedures. As with SMTP, POP is text-based, and as such sends command lines and receives responses, as well as sending instructions for user identification by clients, transmission of passwords, acquisition of mail, and deletion of mail on the server.



MIME

Overview

Audio messages and image files cannot be sent without further processing, if mail is restricted solely to characters. MIME (Multipurpose Internet Mail Extensions) is a specification for the inclusion of various types of data in e-mail, and currently supported by almost all e-mail software for attachment of files. MIME is defined in RFCs 2045 - 2049.

Mime Functions

MIME supports the following functions. • Inclusion of multiple objects in e-mail. other than text, each able to be handled at the receiving

end. • Binary encoding. • Insertion of non-ASCII code characters (eg names in Japanese) in the header. As MIME is a set of conventions which dictate how the main text of the message is to be handled, it employs a character string, referred to as the MIME header, to specify the content and method of encoding used, and to identify whether or not MIME is used in the mail.

Mime Header



Messages using MIME contain a header field as follows.

MIME-Version: 1.0

The use or not of this field determines whether or not the main text of the message follows the MIME conventions. Currently, only Version 1.0 of MIME exists.

MIME Header

Header Meaning Format MIME-Version Indicates that the message uses MIME MIME-Version: 1.0 Content-Type Message data type Content-Type:

Type/Subtype [;parameter] Content-Transfer-Encoding

Encoding method used when sending data

Content-Transfer-Encoding:Encodingtype

Content-ID A unique data ID. Uses the message ID. Content-ID: Message ID Content-Description

Data description Content-Description: “This is MIME Data”

Content- MIME header for future expansion —

[Content-Type] is added to the header to indicate that a message is in MIME format. The [Content-Transfer-Encoding] header is also added as necessary to indicate how the data has been encoded. As some types of data do not require encoding, the [Content-Transfer-Encoding] header is not always required.



The [Content-Description] header is used when including comments. The content of this header is interpreted as comments referring to the content of the message, and has no effect on operation of the software.

Data Types Supported with Mime

The following data types may be specified in the [Content-Type] header. • Text: Information consisting of characters. The ISO-2022-JP character code set is used

in Japan, while US-ASCII is used for ASCII codes. • Image: Still images such as GIF and JPEG data. • Audio: Audio information. • Video: Digital animation such as animation and MPEG. • Application: Various application files and standard data formats. • Multipart: Main text which includes multiple objects. A MIME header is also added within the

message to record other messages. Use of this data type allows sound, animation, and messages to be included in the same e-mail message.

• Message: Text message information.



Multipart

Multipart is a data type which allows inclusion of multiple data items (objects). It allows for the inclusion of text and attached files in messages, and is the most commonly used type. Multipart indicates the inclusion of multiple parts (data) in the main text, while the Contents-Type header indicates how the individual parts are handled. Multipart supports the following sub-types to indicate the relationship between the individual parts. • Mixed: The message consists of multiple independent parts.

• Alternative: The message consists of multiple parts of the same content, but in different format.

• Parallel: The message consists of multiple parts which are reproduced and displayed simultaneously.

• Digest: A collection of RFC822-format messages in digest format.



Example: Received Multipart Mail Header

Received: from f64g.shinyoko.ricoh.co.jp ([133.139.167.30]) by bb.shinyoko.ricoh.co.jp (4.1/2.8Wb-91Jan07) id AA15193; Sun, 15 Feb 98 14:53:50 JST Return-Path: <[email protected]> Message-Id: <[email protected]> Date: 15 Feb 1998 14:54:06 +0900 X-Mailer: ICFAX Version 1.0 Mime-Version: 1.0 Content-Type: multipart/mixed; boundary = “--ICFAX_60670AE6CB--” To: [email protected].

From: [email protected] Mail header Subject: Fax Message NO.0003 from “+81454771786” (“RICOH SERVICE”) text message here ----ICFAX_60670AE6CB-- Content-Type: image/tiff; name = “FAX.TIF”

Content-Transfer-Encoding: base64 Part header Content-Discription: “FAX.TIF”



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 ----ICFAX_60670AE6CB----

A Multipart message contains multiple parts, with the strings which delineate these parts being specified with the boundary parameter. Each part is delineated with

--boundary_string

and the final part is indicated with

--boundary_string--



Binary Data Encoding

The binary data must be encoded as character strings in order to insert a binary file into a text message. In Internet mail, non-ASCII data such as single-byte Katakana in Japanese is not sent correctly. This encoding method is indicated in the [Content-Transfer-Encoding] field in the MIME header. The following encoding methods may be specified in the [Content-Transfer-Encoding] field. • 7-bit: 7-bit code (8th not used) • 8-bit: Full 8 bits used • Binary: Binary data • Base64: Encoding of binary data in base64 notation • Quoted Printable: Encoding of character subject binary data Of the above, only 7-bit, Quoted Printable, and Base64 are normally used with e-mail. Other encoding methods cannot be used unless they are supported over the network.



BASE 64

Base 64 is commonly supported in e-mail application software for the transmission of binary data. This method of encoding takes each six bits of the original binary data and converts it to numbers between 0 and 63, each of these numbers being assigned to one of 64 characters (26 upper case characters of the alphabet, 26 lower case characters of the alphabet, the numbers 0~9, and the + and / symbols). Now that we have covered e-mail basics, we can look at some of the features of an Internet fax in more detail. All examples are taken from the Internet fax option for model H551. This following sections show how the fax machine communicates with other terminals using G3 and e-mail.



Mail Protocol

SMTP Commands

Command Syntax Responses HELO <domain> S:250 <domain>

E:500,501,421 HELO (Hello)

This command is used to identify the sender-SMTP to the receiver-SMTP. The argument field contains the host name of the sender-SMTP. The receiver-SMTP identifies itself to the sender-SMTP in the connection greeting reply, and in the response to this command. This command and an OK reply to it confirm that both the sender-SMTP and the receiver-SMTP are in the initial state, that is, there is no transaction in progress and all state tables and buffers are cleared. MAIL FROM:<reverse-path> S:250

F:552, 451, 452 MAIL (Mail)

This command tells the SMTP-receiver that a new mail transaction is starting and to reset all its state tables and buffers, including any recipients or mail data. It gives the reverse-path which can be used to report errors. If accepted, the receiver-SMTP returns a 250 OK reply. The <reverse-path> can contain more than just a mailbox. The <reverse-path> is a reverse source routing list of hosts and source mailbox. The first host in the <reverse-path> should be the host sending this command.



Command Syntax Responses RCPT TO:<forward-path> S:250, 251

F:550, 551, 552, 553, 450, 451, 452 E:500,501,503

RCPT (Recipient)

This command gives a forward-path identifying one recipient. If accepted, the receiver-SMTP returns a 250 OK reply, and stores the forward-path. If the recipient is unknown the receiver-SMTP returns a 550 Failure reply. This second step of the procedure can be repeated any number of times. The <forward-path> can contain more than just a mailbox. The <forward-path> is a source routing list of hosts and the destination mailbox. The first host in the <forward-path> should be the host receiving this command.



Command Syntax Responses DATA I:354

F:451, 554 E:500, 501, 503, 421 after transmitting data; S:250 F:552, 554, 451, 452

DATA (Data)

If accepted, the receiver-SMTP returns a 354 Intermediate reply and considers all succeeding lines to be the message text. When the end of text is received and stored the SMTP-receiver sends a 250 OK reply. Since the mail data is sent on the transmission channel the end of the mail data must be indicated so that the command and reply dialog can be resumed. SMTP indicates the end of the mail data by sending a line containing only a period. A transparency procedure is used to prevent this from interfering with the user's text. NOTE: The mail data includes the memo header items such as Date, Subject, To, Cc,

From [2]. The end of mail data indicator also confirms the mail transaction and tells the receiver-SMTP to now process the stored recipients and mail data. If accepted, the receiver-SMTP returns a 250 OK reply. The DATA command should fail only if the mail transaction was incomplete (for example, no recipients), or if resources are not available.



Command Syntax Responses SEND FROM:<reverse-path> S:250

F:552, 451, 452 E:500, 501, 502, 421

SEND (Send)

The SEND command requires that the mail data be delivered to the user's terminal. If the user is not active (or not accepting terminal messages) on the host a 450 reply may returned to a RCPT command. The mail transaction is successful if the message is delivered the terminal. SOML FROM:<reverse-path> S:250

F:552, 451, 452 E:500, 501, 502, 421

SOML (Send or mail)

The Send Or Mail command requires that the mail data be delivered to the user's terminal if the user is active (and accepting terminal messages) on the host. If the user is not active (or not accepting terminal messages) then the mail data is entered into the user's mailbox. The mail transaction is successful if the message is delivered either to the terminal or the mailbox. SAML FROM:<reverse-path> S:250

F:552, 451, 452 E:500, 501, 502, 421

SAML (Send and mail)

The Send And Mail command requires that the mail data be delivered to the user's terminal if the user is active (and accepting terminal messages) on the host. In any case the mail data is entered into the user's mailbox. The mail transaction is successful if the message is delivered the mailbox.



Command Syntax Responses RSET S:250

E:500, 501, 504, 421 RSET (Reset)

This command specifies that the current mail transaction is to be aborted. Any stored sender, recipients, and mail data must be discarded, and all buffers and state tables cleared. The receiver must send an OK reply. VRFY <user name> S:250, 251 <full name of

user> F:550, 551, 533 E: 500, 501, 502, 504, 421

VRFY (Verify)

This command asks the receiver to confirm that the argument identifies a user. If it is a user name, the full name of the user (if known) and the fully specified mailbox are returned. This command has no effect on any of the reverse-path buffer, the forward-path buffer, or the mail data buffer. EXPN <mailing list> S:250

F:550 E: 500, 501, 502, 504, 421

EXPN (Expand)

This command asks the receiver to confirm that the argument identifies a mailing list, and if so, to return the membership of that list. The full name of the users (if known) and the fully specified mailboxes are returned in a multiline reply. This command has no effect on any of the reverse-path buffer, the forward-path buffer, or the mail data buffer.



Command Syntax Responses HELP [command] S:211, 214

E: 500, 501, 502, 504, 421 HELP (Help)

This command causes the receiver to send helpful information to the sender of the HELP command. The command may take an argument (e.g., any command name) and return more specific information as a response. This command has no effect on any of the reverse-path buffer, the forward-path buffer, or the mail data buffer. NOOP S:250

E:500, 421 NOOP (No operation) This command does not affect any parameters or previously entered commands. It specifies

no action other than that the receiver send an OK reply. This command has no effect on any of the reverse-path buffer, the forward-path buffer, or the mail data buffer. QUIT S:221

E:500 QUIT (Quit)

This command specifies that the receiver must send an OK reply, and then close the transmission channel. The receiver should not close the transmission channel until it receives and replies to a QUIT command (even if there was an error). The sender should not close the transmission channel until it send a QUIT command and receives the reply (even if there was an error response to a previous command). If the connection is closed prematurely the receiver should act as if a RSET command had been received (canceling any pending transaction, but not undoing any previously completed transaction), the sender should act as if the command or transaction in progress had received a temporary error (4xx).



Command Syntax Responses TURN S:250

F:502 E:500, 503

TURN (Turn)

This command specifies that the receiver must either (1) send an OK reply and then take on the role of the sender-SMTP, or (2) send a refusal reply and retain the role of the receiver-SMTP. If program-A is currently the sender-SMTP and it sends the TURN command and receives an OK reply (250) then program-A becomes the receiver-SMTP. Program-A is then in the initial state as if the transmission channel just opened, and it then sends the 220 service ready greeting. If program-B is currently the receiver-SMTP and it receives the TURN command and sends an OK reply (250) then program-B becomes the sender-SMTP. Program-B is then in the initial state as if the transmission channel just opened, and it then expects to receive the 220 service ready greeting. To refuse to change roles the receiver sends the 502 reply.

Remarks: S: Successful E: Error F: Failure I: Intermediate



SMTP Response Commands

Reply codes Meaning

211 System status, or system help reply

214 Help message [Information on how to use the receiver or the meaning of a particular non-standard command; this reply is useful only to the human user]

220 <domain> Service ready 221 <domain> Service closing transmission channel 250 Requested mail action okay, completed 251 User not local; will forward to <forward-path> 354 Start mail input; end with <CRLF>.<CRLF>

421 <domain> Service not available, closing transmission channel [This may be a reply to any command if the service knows it must shut down]

450 Requested mail action not taken: mailbox unavailable [E.g., mailbox busy]

451 Requested action aborted: local error in processing 452 Requested action not taken: insufficient system storage

500 Syntax error, command unrecognized [This may include errors such as command line too long]

501 Syntax error in parameters or arguments 502 Command not implemented



Reply codes Meaning

503 Bad sequence of commands 504 Command parameter not implemented

550 Requested action not taken: mailbox unavailable [E.g., mailbox not found, no access]

551 User not local; please try <forward-path> 552 Requested mail action aborted: exceeded storage allocation

553 Requested action not taken: mailbox name not allowed [E.g., mailbox syntax incorrect]

554 Transaction failed



POP Commands Command Syntax Responses

USER <name> +OK name is a valid mailbox -ERR never heard of mailbox name

USER

To authenticate using the USER and PASS command combination, the client must first issue the USER command. If the POP3 server responds with a positive status indicator ("+OK"), then the client may issue either the PASS command to complete the authentication, or the QUIT command to terminate the POP3 session. If the POP3 server responds with a negative status indicator ("-ERR") to the USER command, then the client may either issue a new authentication command or may issue the QUIT command. The server may return a positive response even though no such mailbox exists. The server may return a negative response if mailbox exists, but does not permit plain text password authentication. PASS <password> +OK maildrop locked and ready

-ERR invalid password -ERR unable to lock maildrop

PASS

When the client issues the PASS command, the POP3 server uses the argument pair from the USER and PASS commands to determine if the client should be given access to the appropriate maildrop. Since the PASS command has exactly one argument, a POP3 server may treat spaces in the argument as part of the password, instead of as argument separators.



Command Syntax Responses QUIT +OK

-ERR some deleted messages not removed QUIT

The POP3 server removes all messages marked as deleted from the maildrop and replies as to the status of this operation. If there is an error, such as a resource shortage, encountered while removing messages, the maildrop may result in having some or none of the messages marked as deleted be removed. In no case may the server remove any messages not marked as deleted. Whether the removal was successful or not, the server then releases any exclusive-access lock on the maildrop and closes the TCP connection. STAT +OK nn mm STAT The POP3 server issues a positive response with a line containing information for the maildrop. This line is called a "drop listing" for that maildrop. In order to simplify parsing, all POP3 servers are required to use a certain format for drop listings. The positive response consists of "+OK" followed by a single space, the number of messages in the maildrop, a single space, and the size of the maildrop in octets. This memo makes no requirement on what follows the maildrop size. Minimal implementations should just end that line of the response with a CRLF pair. More advanced implementations may include other information. Note that messages marked as deleted are not counted in either total.



Command Syntax Responses LIST [message number] +OK scan listing follows

-ERR no such message LIST

If an argument was given and the POP3 server issues a positive response with a line containing information for that message. This line is called a "scan listing" for that message. If no argument was given and the POP3 server issues a positive response, then the response given is multi-line. After the initial +OK, for each message in the maildrop, the POP3 server responds with a line containing information for that message. This line is also called a "scan listing" for that message. If there are no messages in the maildrop, then the POP3 server responds with no scan listings--it issues a positive response followed by a line containing a termination octet and a CRLF pair. Note that messages marked as deleted are not counted in either total. RETR <message number> +OK message follows

-ERR no such message RETR

If the POP3 server issues a positive response, then the response given is multi-line. After the initial +OK, the POP3 server sends the message corresponding to the given message-number, being careful to byte-stuff the termination character (as with all multi-line responses). DELE <message number> +OK message deleted

-ERR no such message DELE

The POP3 server marks the message as deleted. Any future reference to the message-number associated with the message in a POP3 command generates an error. The POP3 server does not actually delete the message until the POP3 session enters the UPDATE state. NOOP +OK NOOP The POP3 server does nothing, it merely replies with a positive response.



Command Syntax Responses LAST +OK nn LAST The POP3 server issues a positive response with a line containing the highest message number which accessed. Zero is returned in case no message in the maildrop has been accessed during previous transactions. A client may thereafter infer that messages, if any, numbered greater than the response to the LAST command are messages not yet accessed by the client. RSET +OK RSET If any messages have been marked as deleted by the POP3 server, they are unmarked. The POP3 server then replies TOP <message number> <number of lines>

+OK top of message follows -ERR no such message

TOP

If the POP3 server issues a positive response, then the response given is multi-line. After the initial +OK, the POP3 server sends the headers of the message, the blank line separating the headers from the body, and then the number of lines of the indicated message's body, being careful to byte-stuff the termination character (as with all multi-line responses). Note that if the number of lines requested by the POP3 client is greater than the number of lines in the body, then the POP3 server sends the entire message.



Command Syntax Responses APOP <name> <digest> +OK maildrop locked and ready

-ERR permission denied APOP

Normally, each POP3 session starts with a USER/PASS exchange. This results in a server/user-id specific password being sent in the clear on the network. For intermittent use of POP3, this may not introduce a sizable risk. However, many POP3 client implementations connect to the POP3 server on a regular basis -- to check for new mail. Further the interval of session initiation may be on the order of five minutes. Hence, the risk of password capture is greatly enhanced. An alternate method of authentication is required which provides for both origin authentication and replay protection, but which does not involve sending a password in the clear over the network. The APOP command provides this functionality.



Mail Transmission

IFAX SMTPServer

E-mail

LANRouter

Router

InternetIFAXPOP/IMAP

ServerE-mailLAN

Sending Terminal

Reception usingPOP or IMAP

E-mail IFAX

Reception usingSMTP

ServerDNS

H132D551.WMF



Procedure Scanned documents are sent as electronic mail (e-mail). All messages are sent using memory transmission. When a backup mail address (Bcc address, also known as Blind carbon copy) has been stored with the NIC Fax user settings, the machine also sends the message to all the Bcc address. All e-mail transmissions are controlled using Simple Mail Transfer Protocol (SMTP) procedures. There must be an SMTP server on the same LAN as the sending machine, or the machine will not be able to send e-mail (it is not necessary to set up an SMTP account). NOTE: ‘IFAX’ is the same as ‘NIC FAX’. Some models use the name ‘IFAX’. Others use the name

‘NIC FAX’.



Mail Transmission using a PDU (PSTN Dial-up Unit) As explained above, you cannot send e-mail using the NIC fax if you do not have an SMTP server on your LAN. A customer using the H535 model can send mail without an SMTP server if you install the optional PDU kit. The PDU controls protocols for communication between then Internet Service Provider (ISP) and the fax machine. The PDU also converts scanned image data to MIME format for e-mail.

IFAX

LAN

Router

Router

Internet IFAXPOP/IMAPServer

E-mail

LAN

Sending Terminal

SMTPServer

E-mail

Internet ServiceProvider



The fax machine sends the mail to the ISP, and the SMTP server at the ISP sends the mail over the internet to the destination. During transmission, the FCU detects a dial tone and then dials the telephone number for the ISP. After connecting to the ISP, the NCU changes the data line relay from the FCU to the PDU. This connects the PDU to the PSTN line.

Data Formats The scanned data is converted into a TIFF-F formatted file (only MH compression can be used). Some models also allow DCX; in these models, the file format depends on a user setting (for more on image file formats, see Image Files). The fields of the e-mail and their contents depend on the model (see below).

Example: H551 Field Content

From Mail address of the sender Reply-To Mail address to be replied To Mail address of the destination Bcc Blind carbon copy address (backup mail address) X-Mailer ICFAX Version 1.0 (ICFAX is a Ricoh mail utility - IC

means Image Communication) Subject Fax message no. xxxx (file number) from the TSI (see the

notes below this table)



Field Content Content-Type Multipart/mixed

Attached files: image/tiff, application/octet-stream Content-Transfer-Encoding Base 64 Message Body MIME-converted DCX or TIFF-F (MIME standards specify

how files are attached to e-mail messages)

NOTE: 1) The message no. will exist in the subject field if no TSI or RTI is registered.

2) The label of the personal code and RTI will appear at the end of the subject field, if the personal code is entered.

3) The file number can be checked on the TCR/Journal.



Errors An error report will be generated if an error occurs during the communication between the machine and the SMTP server. However, it is possible that the sender will not receive notice of errors that occurred between the SMTP server and the receiving terminal. For what happens when an error occurs when the machine is receiving, refer to the Mail Reception section.

Secure Internet Transmission To transmit e-mail via the Internet more securely, use SMTP authentication, and POP before SMTP for IFAX.

SMTP Authentication. SMTP Authentication requires user authentication before they can access the server. This prevents unauthorized access to the server. To use SMTP authentication, your server must support CRAM-MD5, PLAIN, or LOGIN. The account name and password specified in the “Mail Server” settings are used for SMTP authentication. Other account names and passwords cannot be specified.

POP Before SMTP. Prevents unauthorized access to the SMTP server and requires users to access and log onto the POP3 server before sending e-mail.



Mail Reception – Overview Internet fax machines support three types of e-mail reception: • POP3 (Post Office Protocol Version 3.) • IMAP4 (Internet Messaging Access Protocol Version 4) • SMTP (Simple Mail Transfer Protocol).

POP3 picks up the mail from a POP3 server and deletes it from the server. The machine can be adjusted to keep the mail on the server. IMAP4 also picks up the mail from a server, but does not delete the mail from the server. • Concerning the deletion of mail after reception, the server’s settings may take priority over the

machine’s settings. With SMTP, a mail server is not needed. However, the network administrator must register the NIC fax machine as an SMTP server in the MX record of the DNS server. Then the NIC fax will receive the mail automatically without the machine having to pick it up from a server. The machine can be adjusted to select one of these types of reception. However, if SMTP is selected and the machine is not registered in the MX record of the DNS server, then either IMAP4 or POP3 will be used. Some older models only support reception using POP3.



Mail Reception – POP3

Procedure In order for the fax machine to receive e-mail, 1) there must be a POP3 server on the same LAN as the NIC Fax, and 2) an account must be set up for the fax machine. There are two ways to receive mail from the server: automatic, and manual.

NIC Fax SMTPServer

E-mail

LANRouter

Router

InternetNIC FaxPOP

ServerE-mail

LAN

ReceivingTerminal

H132D562.WMF



Automatic E-Mail Reception

The machine calls the POP server at a regular interval to check if any e-mail has come in. The interval is adjustable. The default setting is normally 3 minutes.

Manual E-mail Reception

The manual e-mail reception function can be stored in a Quick Operation Key. When the key is pressed, the machine calls the POP3 server immediately. The timer for automatic e-mail reception is not reset when the machine calls the POP3 server manually. Here is an example of the sequence • Automatic e-mail reception interval: 30 minutes. • The machine calls the POP3 server (automatic e-mail reception) • 10 minutes later, the user calls the POP3 server (manual e-mail reception) • The machine will call the POP3 server again automatically after 20 minutes. Reception Process

When new e-mail is detected, the server receives the mail. If the POP server is holding several e-mails for the NIC fax, the machine picks up the e-mails one at a time, in the order of arrival at the server. Mail is not picked up if memory is low. The machine will wait until sufficient memory is free. E-mail reception is done in accordance with Post Office Protocol version 3.0 (POP3) procedures.



Mail Reception using a PDU (PSTN Dial-up Unit) As explained above, you cannot receive e-mail using the NIC fax if you do not have a POP server on your LAN. A customer using the H535 model can receive mail without a server if you install the optional PDU kit The PDU controls protocols for communication between then Internet Service Provider (ISP) and the fax machine. The PDU also converts scanned image data to MIME format for e-mail.

IFAX SMTPServer

E-mail

LANRouter

Router

Internet

IFAX

E-mail

LAN

ReceivingTerminal

POPServer

Internet ServiceProvider

For more about the PDU kit, please refer to Mail Transmission using a PDU.



Characteristics of POP3/IMAP4 Reception Here are some general characteristics of POP3 receiving. They also apply to reception using IMAP4.

No MX record registration. There is no need to register the machine in the MX record of the DNS server.

Power can be switched off. As long as the machine is not receiving mail, mail stored in the mail server is not lost when the power is switched off. With SMTP reception, if the machine is switched off, the SMTP server sends an error report back to the sender, and the machine will not receive the mail unless the sender sends it again after the machine is switched on.

Dial-up compliance. POP3 can be accessed spontaneously, making it ideal for dial-up operation.



Mail Reception – IMAP4 The descriptions in the previous section (Mail Reception - POP3) also apply for reception using IMAP4, except for the following. • E-mail reception is done in accordance with IMAP4 procedures. • There must be an IMAP4 server on the same LAN as the fax machine. • IMAP4 does not automatically delete the mail from the server after picking it up.



Mail Reception – SMTP IFAX SMTP

ServerE-mail

LANRouter

Router

InternetIFAX

LAN

ReceivingTerminal

E-mail

ServerDNS

SMTP Mail Reception Procedure By registering the IFAX as an SMTP server in the MX record of the DNS server, you can enable direct receiving of mail from the SMTP server. The fax machine does not call the server to pick up the mail (as is done in the POP/IMAP protocol using either automatic or manual e-mail reception). Also, with SMTP, the received mail can be routed to another fax (this is known as ‘delivery’). NOTE: ‘IFAX’ is the same as ‘NIC FAX’. Some models use the name ‘IFAX’. Others use ‘NIC FAX’.



Required Settings • The IFAX must be registered as an SMTP server in the MX record of the DNS server, and the

address of the received mail must specify the IFAX. • SMTP reception must be enabled on the fax machine (normally a user tool).

However, if SMTP reception is selected and the machine is not registered in the MX record of the DNS server, then either IMAP4 or POP3 is used, depending on the setting:



SMTP Reception Characteristics • Delivery of received mail. The ‘Off Ramp Gateway’ feature allows expansion for RX mail delivery

to a G3 fax. The machine transfers incoming mail is sent to the G3 fax specified by the local part. For example, in a destination address specified as:

[email protected]

the ‘local part’ is 0454778907. • A POP3/IMAP4 server is not required. For example, in an environment where there is only a

UNIX server or in an intranet environment where Notes is used for mail, mail received from outside is handled via the SMTP gateway.

• Immediacy of response is slightly better. There is no interval in the acquisition of mail as with POP3/IMAP4, thus slightly improving the response time.

• Easier error handling. When an error occurs with POP3/IMAP4, the receiving terminal sends an error mail back to the sender in order to inform them that an error has occurred. With SMTP mail reception, however, in almost all cases the SMTP server sends the error mail to the sender.

• Disadvantage: If the machine’s power is switched off when mail comes in, the SMTP server receiving the mail will send an error report back to the sender and delete the mail. It will not keep it for the machine to pick up next time it switches on. The sender has to resend the mail.

The user may be able to check a log on the SMTP server to see if any mail came in and was sent back during the night. Nothing can be done on the NIC fax machine. With POP3 and IMAP4, the user can switch the machine off and the server keeps the mail.



Delivery: Transferring Mail Received With SMTP (Off Ramp Gateway)

Overview

If the address of the mail received with SMTP contains the following information, it can be delivered to another G3 fax: Fax = “ Delivery Number”@”IFAX Host Name.Domain”

IFAX

Router

IFAX

DNS SMTP

SMTP

Router

SMTP

SMTP

Telephone LineTransmission

SwitchingStation

SwitchingStation

IFAX

R

R

PSTN

DNS

(SMTP Receive Setting:[email protected])

(Address:fax = [email protected])

Internet/Intranet



How to Set Up Mail Delivery

The sender must set the mail address in the following format: 1) When dialing using a fax number

fax=<Delivery Destination Fax Number>@<IFAX Host Name>.<Domain Name> Example: [email protected]

Delivers to fax number 0454771459

2) When dialing using a Quick dial destination

fax=<# Quick Dial Number>@<IFAX Host Name>.<Domain Name> Example: fax=#[email protected] Delivers to the number registered for

Quick Dial key 001.

3) When dialing using a Group destination

fax=<#**Group Dial Number>@<IFAX Host Name>.<Domain Name> Example: fax=#**[email protected] Delivers to numbers registered for

Group dial key 05.



Mail Delivery Conditions 1) The machine must be set up for SMTP mail delivery: 2) If the user wishes to limit this feature so that the machine will only deliver mail from designated

senders, the machine’s “Auth. E-mail RX” feature must be selected 3) If SMTP reception has been disabled, and if there is mail designated for delivery, then the

machine responds with an error. 4) The “fax=” setting does not distinguish between upper and lower case letters. 5) More than one destination cannot be specified in the mail address. A Group counts as 1

destination. 6) If the quick dial, speed dial, or group dial entry is incorrect, the mail transmission is lost, and

the Internet fax machine issues an error to the SMTP server and outputs an error report.



Authorized E-mail Reception

Authorized e-mail reception prevents all except certain specified senders from using your NIC fax machine. To limit access to mail delivery, the addresses of senders must be limited using the Access Limit Entry.

1) Access Limit Entry For example, to limit access to @ifax.ricoh.co.jp:

[email protected] Matches and is delivered. [email protected] Does not match and is not delivered. [email protected] Does not match and is not delivered.

2) Conditions

• If the Access Limit Entry address and the mail address of the incoming mail do not match, the incoming mail is discarded and not delivered, and the SMTP server responds with an error. However, in this case an error report is not output.

• If the Access Limit Entry address is not registered, and if the incoming mail specifies a delivery destination, then the mail is delivered unconditionally.



Other Points Concerning E-Mail Reception

Errors during reception

Errors during POP3/IMAP4 procedures

When an error of this type occurs, the machine stops receiving and the message stays in the server. An error report is output. After a prescribed interval, the machine calls the server and starts to receive, starting with the interrupted message. If there is an incomplete received message in memory, it will be erased.

Abnormal Files

When an error of this type occurs, the machine stops receiving and commands the server to erase the message. Then the machine prints an error report out and sends information about the error by e-mail to the sender’s address (in the “From” or “Reply-to” field of the message). If there is an incompletely received message in the machine’s memory, it will be erased. The machine prints an error message when it fails to send a message after a certain number of attempts.



Abnormal files are as follows: 1. The e-mail has an unsupported MIME header.

Supported types of MIME header depend on the model.

Example: H551 Header Supported Types

Content-Type Multipart/mixed, text/plain, message/rfc822 Image/tiff, application/octet-stream

Charset US-ASCII, ISO-2022-JP, Others are determined to be US-ASCII.

Content-Transfer-Encoding Base 64, 7-bit, 8-bit

2. MIME decoding error 3. The machine cannot recognize the file format as TIFF-F (some older models also accept DCX). 4. The resolution, document size, or compressed type cannot be accepted.

Remaining SAF Capacity Error

The machine CALLS the server but does not receive e-mail if the remaining SAF capacity is less than a certain value (the value depends on a bit switch setting). The e-mail will be received when the SAF capacity increases (for example, after substitute reception files have been printed). Also, if the capacity of the SAF memory goes down to zero during reception, the machine acts in the same way as when receiving an abnormal file (refer to ‘Abnormal files’).



Paper Size

1. If the incoming message is wider than the maximum paper width specification for the machine, an error is generated. The procedure is the same as when receiving an abnormal file.

2. When the machine receives a message that is wider than the paper currently in the paper trays (but within machine specs for image width), the machine reduces the data to fit on the paper in the tray and prints it.

Printing

When a line of text is longer than the paper width, the excess data will be deleted.

Multi-part When a multi-part e-mail message contains several text parts and binary files, the message will be divided with boundaries. Then, each part will be printed separately. If the machine cannot determine where the boundary is, it will generate an error report and print, then send error information e-mail back to the sender.



Secure Internet Reception APOP. Passwords are encrypted when e-mail is received, making it safer than POP3 authentication (clear text), which is not encrypted. APOP requires a POP server that supports APOP.

IMAP-AUTH (Mail Reception). If the IMAP Server supports the AUTHENTICATE command (CRAM-MD5, PLAIN, or LOGIN confirmation), then higher-level security confirmation can be implemented for users logging in. These features can be enabled with user tools. Security is needed for reception using POP/IMAP, because the mail is stored in the POP/IMAP server and the machine must call and pick it up. Security ensures that the mail goes to the correct machine. For reception using SMTP, the mail goes directly to the destination address (it is not held on a server), so this type of security is not needed.



Mail Broadcasting (e-Mail and G3 FAX are combined)

The machine can send the same message to several destinations in one operation. Some destinations can be G3 fax and some can be e-mail. For the G3 fax transmissions, each address has to be dialled separately. However, all the e-mail addresses can be sent with the message to the SMTP server in one transmission. The SMTP server then sends the message to each destination.

E-mailtransmission

LAN

G3 Transmissions(PSTN)

NIC Fax

E-mail Transmissions(LAN/Internet)

SMTPServer

H132D552.WMF



The following example for broadcasting to three e-mail destinations and two G3 fax destinations shows how G3 fax messages are each sent individually, but the e-mail destinations are all sent to the server at the same time. • Order of inputting the addresses at the operation panel

G3 fax (1) - mail (1) - G3 fax (2) - mail (2) - mail (3) • Order of transmission

G3 fax (1) - mail (1), (2), (3) [these 3 sent to the server at the same time] - G3 fax (2)

The SMTP server cannot broadcast the message if a feature included individual information for each terminal in the transmitted data (such as label insertion). If this type of feature was used, the machine sends the e-mails to the server one by one. To send the messages to the server at the same time, the batch transmission feature must be enabled in the Internet fax machine. The maximum number of e-mail destinations in a broadcast depends on the mail server’s limits.



Transfer Request

Operation at the Transfer Requester

Making a Transfer Request by E-Mail

SMTPServer

E-mail

LANR

POPServer

E-mail

E-mail

LAN

Individual G3Transmissions

(PSTN)TransferStation

NIC Fax

TransferRequester

G3 End Receivers

NIC Fax

SMTPServer

Individual E-mailTransmissions

E-mail EndReceivers R

(several destinations,one transmission)

R: Router

E-mail (one transmissionfor each destination)

H132D553.WMF



The requesting terminal dials the transfer station, and requests it to transfer the message to end receivers stored as quick dials, speed dials, and group dials in the transfer station. A quick dial number is indicated by a “#” and two or more digits, a speed dial is indicated by “#’, “*”, and two or more digits, and a group dial is indicated by “#” and “**” and two or more digits. This is the same as for transfer request in a normal fax machine. The destinations can be a mixture of e-mail and G3 fax addresses. However, only an Internet fax can be specified as a transfer station if the end receivers include e-mail addresses. The transfer request goes to the SMTP server as an e-mail message. The quick/speed/group dials (and the ID code) are included in the mail body field of the e-mail as text. The message arrives at the POP server of the transfer station. The transfer station then does the following (see Operation at the Transfer Station for details). • The transfer station picks up the transfer request. • The transfer station sends the message to the G3 destinations one-by-one. • The transfer station sends the message to its SMTP server once. The SMTP server sends the

message to the e-mail destinations one-by-one. The transfer station sends back a transfer result report. The original may be attached to the transfer result report, depending on the G3 settings of the fax machine. For transmissions to e-mail end receivers, the transfer result report only indicates whether the message was successfully transmitted from the transfer station to its SMTP server. The transfer station sends an error report to the requester if it fails to transfer the message to an end receiver. However, if the selected transfer station cannot handle transfer requests, or cannot handle e-mail, no error report is returned to the transfer requester.



The fields of the e-mail and their contents depend on the model.

Example: H551 Field Content

From E-mail address of the requesting terminal To Destination address (transfer station’s address) Bcc Blind carbon copy address (backup mail address) X-Mailer ICFAX version 1.0 Subject Fax Message No. xxxx (file number) from theTSI Content-Type Multipart/mixed

Text/Plain (for a text part), image/tiff or application/octet-stream (for attached files)

Content-Transfer-Encoding Base 64 Mail body (text part) RELAY-ID-: xxxx (xxxx: 4 digits for an ID code)

RELAY: #01#*01#**01…. Message body MIME-converted TIFF-F or DCX



Making a Transfer Request by G3 FAX

The procedures are the same as for a normal G3 fax machine. The requesting NIC fax contacts the transfer station by G3 over the PSTN. The requesting terminal dials the transfer station, and requests it to transfer the message to end receivers stored as quick dials, speed dials, and group dials in the transfer station. Using NSF, the machine sends an ID code and the machine’s own telephone number. Up to 30 end receivers can be requested. End receiver destinations can also be selected using tonal signals, in the same way as for other recent fax models. E-mail address can also be selected in this way, as end receivers and as the destination for receiving the transfer result report. The receiving NIC fax machine receives the transfer request on the PSTN connection. It then handles the transfer request in the same way as explained in “Making a Transfer Request by E-Mail’.

LAN

TransferStation

E-mail

PSTN

G3 Transmission (Transfer Request)

RequestingTerminal

G3 Transmission (Report)

G3 End Receivers

SMTPServer

E-mail EndReceivers

NIC FAX

NIC FAX

H132D554.WMF



Operation at the Transfer Station

Handling a Transfer Request Received by E-Mail

SMTPServer

E-mail

LANR

POPServer

E-mail

E-mail

LAN

Individual G3Transmissions

(PSTN)TransferStation

NIC Fax

TransferRequester

G3 End Receivers

NIC Fax

SMTPServer

Individual E-mailTransmissions

E-mail EndReceivers R

(several destinations,one transmission)

R: Router

E-mail (one transmissionfor each destination)

H132D555.WMF



The NIC fax polls the POP server at regular intervals, as mentioned in a previous section. If the server has received a transfer request, the fax machine receives it from the server in the form of an e-mail message. The end receivers are included in the text part of the message. The machine then sends the message to the end receivers by G3 fax or e-mail, depending on the type of end receiver address, in the same way as described for Broadcasting. The NIC fax sends each G3 fax as an individual transmission. However, for the e-mail, the NIC fax sends the message to the SMTP server once, and the server broadcasts the message to the e-mail end receivers one at a time. The transfer station sends back a transfer result report to the address in the From field of the received e-mail. If an administrator's address is registered, the result report is also sent to that address. The original may be attached to the transfer result report, depending on the G3 settings of the fax machine. For transmission to e-mail end receivers, the transfer result report only indicates whether the message was successfully transmitted from the transfer station to its SMTP server (the transfer station does not know if the messages were received successfully at the end receivers). The transfer station prints an error report if it cannot send the result report to its SMTP server.



Handling a Transfer Request Received by Fax

When the machine receives a transfer request by G3 fax, it sends the message to the various e-mail and G3 end receivers in the same way as for a request received by e-mail. The machine sends back the transfer result report to the requesting terminal’s telephone number, which it specified in the NSF signal. If the machine cannot send this report back to the requesting terminal, it prints the report itself, so that the user can contact the other party. The NIC Fax can accept end receiver destinations and transfer result report destinations that were sent from the requester as DTMF tones. This applies for e-mail or PSTN G3 addresses.

LAN

TransferStation

E-mail

PSTN

G3 Transmission (Transfer Request)

RequestingTerminal

G3 Transmission (Report)

G3 End Receivers

SMTPServer

E-mail EndReceivers

G3 FAX

NIC FAX



Transfer Result Reports for Multi-step Transfer

If All Links Are By E Mail

After it has passed on the transfer request to the next transfer station, each transfer station sends a transfer result report back to the previous transfer station in the chain by e-mail. The main point is that the reports are only sent back one link in the chain. The requesting terminal has no idea what happened further along the chain. The bottom part of the drawing shows details of the route from Transfer Station A back to the requesting machine.



The procedure is as follows. 1. The requesting terminal requests transfer station A to transfer a message. 2. Transfer station A passes the request on to transfer station B. 3. Transfer station A sends a transfer result report back to the requesting machine. 4. Transfer station B passes the request on to transfer station C. 5. Transfer station B sends a transfer result report back to transfer station A.

Requesting Terminal(NIC Fax)

Transfer Station A(NIC Fax)

e-mail Transfer Station B(NIC Fax)

e-mail Transfer Station C(NIC Fax)

e-mail

SMTPServer

e-mail

LAN

POPServer

SMTPServer

Transfer result report

LAN

NIC FAX TransferStation A

NIC FAX

POPServer

SMTPServer


Requesting Terminal


H132D557.WMF



6. The broadcasting station (transfer station C) sends the message to its SMTP server (e-mails) and to the G3 destinations.

7. Transfer station C sends a transfer result report to transfer station B (for e-mail end receivers, it only indicates whether the message was successfully passed on to transfer station C’s SMTP server).

NOTE: The requesting machine’s own telephone number is not included in a transfer request message by e-mail, so the transfer station at the end of the chain cannot send a report back directly to the requesting machine. The requesting terminal only receives a report of how the communication went between transfer stations A and B.



If Some Links Are G3 Fax

This example shows that even if there is only one e-mail link in the chain, the transfer result report from the final transfer station cannot get back to the requesting terminal. (The bottom part of the drawing shows details of the route from Transfer Station A back to the requesting machine.)

The procedure is exactly the same as for a request by e-mail, as described on the previous page. However, if there are two or more consecutive PSTN links in the chain, the transfer station at the end of the PSTN chain will be able to send a transfer result report back to the machine at the start of the PSTN chain. For example, if only the link between transfer stations B and C is e-mail, transfer station B will be able to send a report all the way back to the requesting terminal. If there is even one e-mail link, continuity is broken. The requesting terminal can only get a report from the final transfer station if all links are G3.

G3 Fax

LAN

NIC Fax TransferStation A

SMTPServer

PSTNRequesting Machine

Transfer resultreport (G3 tx)

Requesting Machine(G3 Fax)

Transfer Station A(NIC Fax)

PSTN Transfer Station B(NIC Fax)

e-mail Transfer Station C(NIC Fax)

PSTN



Example of a Transfer Request and Result Report

The steps of the transfer request are as follows:

1. G3 Fax 1 sends a transfer request to NIC Fax 1 by G3 fax (➀ in the diagram).

2. NIC Fax 1 sends e-mail to E-mail Server 1 (➁ in the diagram).

3. E-mail Server 1 sends e-mail to E-mail server 2 (➂ in the diagram).

4. E-mail server 2 sends e-mail to NIC Fax 2 (➃ in the diagram).

LAN

Japan

PSTN


G3 FAX 1

Internet

Europe

G3 Fax 2 PSTN

LAN

Router

Router

Error mail

E-mail Server 1(SMTP/POP)

E-mail Server 2(SMTP/POP)NIC Fax 2

Error mailTransfer result e-mail

➀

➄ ➃

➂

➁NIC Fax 1

H132D559.WMF

[A] [B]

[D] [C]



NOTE: Steps 2 to 4 assume that NIC Fax 1 sends the transfer request to NIC Fax 2 by e-mail, and not G3 fax.

5. NIC Fax 2 sends a G3 fax message to G3 Fax 2 (➄ in the diagram). The steps for sending the transfer result report and any mail reporting errors is as follows:

1. NIC Fax 1 sends a transfer result report [A] to G3 Fax 1 after ➀ in the diagram.

2. When an error occurs at ➂, e-mail server 1 sends e-mail reporting an error [B] to NIC Fax 1. Error mail is also sent to the administrator if the address has been registered in NIC Fax 1.

3. When an error occurs at ➃, e-mail server 2 sends e-mail reporting an error [C] to NIC Fax 1. Error mail [C] is also sent to the administrator if the address has been registered in NIC Fax 1.

4. NIC Fax 2 send a transfer result report [D] to NIC Fax 1 through e-mail server 1 and e-mail server 2 after transferring the message to the end receivers (after ➄ in the diagram).



Autorouting

The sending G3 fax machine appends a code to the telephone number. This code is sent in G3 protocol to the NIC Fax in the SUB code. When a G3 fax message is received with a SUB code, the machine compares the SUB code with the personal codes stored with Personal Boxes and Transfer Boxes in the machine. If there is a match, the machine routes the message to the e-mail address in the Personal Box by e-mail. (If the SUB code corresponds to a Transfer Box, the machine routes the message to all the addresses in the Transfer Box). A communication failure report will be printed if a transmission error occurs between the machine and the SMTP server.

G3 Fax

LAN

NIC FaxSMTPServer Forwarding by

e-mail

PSTN

G3 Transmission with SUB code

H132D560.WMF



Conditions

1. E-mail addresses for autorouting must be registered in the machine with personal codes in Personal Boxes and/or Transfer Boxes.

2. If the received SUB code specifies confidential reception, the message at the NIC fax can be received using confidential reception. However, when this message is forwarded by e-mail, the ‘confidential’ attribute is not passed on – you cannot specify confidential reception by e-mail.

3. The RTI or CSI of the forwarding machine is indicated in the subject field of the forwarded e-mail. 4. Autorouting only works for incoming G3 faxes. It does not work for incoming e-mails, because

there are no SUB codes in the e-mail protocol.



- Example -

1. The sending terminal sends a fax message with a SUB code “1111” to the NIC Fax. 2. Personal code 1111 in the receiving NIC fax has been allocated to a PC on the network. The NIC

fax makes an e-mail out of the incoming fax message, then sends the e-mail to that PC.

G3 Fax

LAN

NIC FAXSMTPServer

e-mail

PSTN

G3 Transmission

SUB code: 1111

ClientPC

E-mail address:[email protected]

Personal Code 1111:[email protected]

H132D561.WMF

[A]



Forwarding Forwarding is a similar feature to autorouting, useful when the sending machine cannot send SUB codes. • The sending machine must have the RTI and CSI programmed. • The receiving machine must have already specified a destination PC e-mail address for messages

received with that RTI/CSI. • The message can only be forwarded to one destination.



LAN Fax Transmission

ClientPC NIC Fax

Request tosend fax

LANe-mail

G3 Transmission

SMTPServer

PSTN

PC fax applicationinstalled

This section shows how a PC on the same network can: • Send a document created with a PC application, through the NIC fax, to another fax machine by

G3 or by e-mail. The destination fax machine does not need a NIC fax card, because the message goes out over the PSTN.

• Print out a document created with a PC application, using the NIC fax as a printer. Normally, this is not so effective as installing a printer controller option. There are fewer features and resolution settings available with the LAN fax driver.

This feature is known as LAN Fax. The following items and settings are required to use this feature: • A NIC Fax and a PC connected to a LAN. • The initial settings set up correctly on the NIC FAX (such as the IP Address, Subnet Mask, and

Default Gateway settings). Refer to the documentation for the model. • Software installed on the PC (depends on the model)

Example: H231: SmartNet Monitor for Client, the LAN Fax driver, and an Address Book



IP-Fax

What is IP-Fax? This feature allows you use TCP/IP to communicate with fax machines. The other party can be on the same TCP/IP network as your machine, or it can be on the internet anywhere in the world. • It can also be on a public telephone network, if your intranet has a Gateway to interface with the

public telephone network. Modem speed in this case is below V.17. • If the other fax machine is connected directly to a TCP/IP network, it must use T.38 protocol. IP-Fax uses a Group 3 style fax protocol, but in packets to conform to TCP/IP. No e-mail server is required (compare with internet fax). Use the IP address (or host name) to dial the destination machine, instead of the fax number. • If there is a Gatekeeper on your intranet, you can use the ‘alias number’ stored in the gatekeeper.

The gatekeeper stores a look up table of ‘alias fax numbers’ and actual IP addresses.IP-Fax is faster than PSTN.

Direct connection with the other party’s machine is possible, so function capability information can be exchanged and transactions can be confirmed.



The diagram below shows the three methods of data transmission.



Note how cases , , and operate in the illustration above: • Case : The NIC Fax, connected to the Internet/Intranet via a VoIP gateway connected to

telephone network, sends a transmission through the Gateway (address: 192.168.1.64) to the destination fax number (212 123 5678). (The Host Name can be substituted for the IP Address.)

• Case : The NIC Fax, connected to the Internet/Intranet using a VoIP gatekeeper, sends a transmission to the destination with the alias fax number 212 333 6666 through VoIP gatekeeper 192.168.1.20.

• Case : The NIC Fax, connected to the Internet/Intranet, sends a transmission to IP Address 192.168.1.10 or to Host Name IPFAX1 (192.168.1.10). The IP Address and Host Name must be previously registered on the DNS server.

Note the difference between the ‘gateway’ and the ‘gatekeeper’. A gatekeeper contains a list of IP addresses of destinations, and an ‘alias number’ for each one. The alias numbers allow you to use telephone numbers instead of IP addresses when sending a message. This may be more convenient for many people. When you specify one of these alias numbers as the destination, the gatekeeper wakes up and passes your fax to the destination over your LAN or the Internet. To set up your machine for using a gatekeeper, do the following: 1. Store the gatekeeper’s IP address in the NIC fax machine. 2. Store your ‘own fax number’. This will be your NIC fax machine’s alias number. It is convenient to use the machine’s telephone number, but any number will do.



3. Make sure that your NIC fax machine’s IP address is stored already in the NIC fax machine with the user tools. 4. Your machine will then automatically contact the gatekeeper, and your machine’s IP address and alias number will be registered with the gatekeeper. This works even if the gatekeeper is on a different LAN, or over the internet, as long as the gatekeeper’s IP address is input correctly. To set up an ‘alias number’ network of NIC fax machines on different LAN segments or internet locations, all machines will have to register with the gatekeeper using the above procedure. There only needs to be one gatekeeper in this network. The gatekeeper system will not work if there are any firewalls in the network. A VoIP gateway interfaces your LAN with the public telephone network. If you input the IP address of the gateway and the destination fax number, the gateway will handle things from there, converting the TCP/IP frames into T.30 fax protocol. • VoIP: Voice over IP. This allows voice frequency tones to be send out over TCP/IP. Internet

telephones use this technology. However, with the NIC fax, voice message transmission is not possible.



Features of IP-Fax IP-Fax provides these features: • Compliance with ITU-T T.38 Standards. • Employs TCP/IP communication protocols. • Allows destinations to be identified by the IP Address, Host Name, or an Alias Telephone Number. The main advantages of IP-Fax are: • Costs are reduced as the main method of communication is over the Internet. • All transactions can be confirmed because the machine is connected directly to the other party. • Extremely high speed because IP-Fax can operate over a 10/100Base LAN. The disadvantages of IP-Fax are: • Communication through firewalls is not possible. • Communication via gateway is the only method of transmission. • High visibility (poor security).

NOTE: The transmission speed of IP-Fax is affected by the condition of the network (distance of wiring, packet loss, etc.). IP-Fax operates in real time, so IP-Fax must occupy one line until the other party’s machine breaks communication.

IP-Fax can use all G3 fax features except the following: • Sending: Memory file transfer, batch transmission • Receiving: Batch reception



T.38 Transmission Protocol The T.38 transmission protocol handles data in packets in order to allow IP-Fax to transmit with a T.30 G3 fax protocol network.

(1) Transactions in an Intranet (2) Transactions Between PSTN and Intranet

NIC FAX NIC FAX

T.30 IND: Flags

V21: HDLC:CSI/FCS

DIS/FCS-Sig-End

H231D923.WMF

GATEWAY NIC FAX

T.30 IND: Flags

V21: HDLC:CSI/FCS

DIS/FCS-Sig-End

G3FAX

Flags

CSI

DIS

H231D924.WMF



Packet Format Fax communications are conducted with T.38 IFP (Internet Fax Protocol) packet exchange via the Internet. TCP or UDP (protocols that employ two different packet formats) can be selected for transmission. TCP is selected by default for NIC Fax; you can change this to UDP with a bit switch adjustment.

TCP Packet Format

TCP requires more time because it requires a confirmation response. However, TCP is more reliable because it always demands an affirmative response and requests a retry in response to an error.

Packet 1

Packet 2

Packet 2

ComfirmResponse

ResendRequest

H231D925.WMF

T.30 IDExtension T.30 DataIP + TCP

Header

H231D926.WMF



UDP Packet Format

UDP is output without establishing the session. The UDP protocol does not correct errors or attempt re-sending. While it is much faster, generally its reliability is lower. However, on the receiving side with IP-Fax the speed is forced lower to prevent data overflow, making UDP slower than TCP. NOTE: As a general rule, UDP is faster than TCP but slightly less reliable. On the other hand, TCP

is more reliable than UDP but slightly slower.

Packet 2 Packet 0 Packet 0




Used for Error Correction

Receive Send

H231D927.WMF



UDP appends a redundant packet to the data packet and sends both. At the NIC Fax, the redundant packet is attached to only Phase C and the post message. The number of redundant packets can be changed as shown below. However, increasing the number of redundant packets increases the size of the data and slows down the speed of the transmission.

UDP Related Adjustments

IP FAX Delay Level Raise the level by selecting a higher setting if too many transmission errors are occurring on the network. If TCP/UDP is enabled on the network, raise this setting on the T.30 machine. Increasing the delay time allows the recovery of more lost packets. If only UDP is enabled, increase the number of redundant packets. Level 1~2: 3 Redundant packets Level 3: 4 Redundant packets

SequenceNumber

T.30 IDExtensionIP + UDP

HeaderT.30 Data Redundant

PacketRedundant

Packet

H231D928.WMF



E-Mail Options

Subject and Level of Importance You can enter a subject message with a user tool. The Subject entry for the mail being sent is limited to 64 characters. The subject can also be prefixed with an “Urgent” or “High” notation.

E-mail Messages After entering the subject, you can enter a message with a user tool.



Message Disposition Notification (MDN)

IFAX

Router

Server

Internet

RReception Confirmation Optioin [email protected]

ServerServer

ModemRouter

IFAX

[email protected]

RRMail (Request receive

respone)

IFAXIFAX

TX ManagementReport

ConfirmMail (Answer to Reception

Confirmation Request)

* * * JOURNAL * * *

10:17AM [email protected] MailSMQ 0'09" 2 - -

Time ADDRESS Mode T ime PAGE RESULT

Confirmation(TX Management

Report)

OK

* * * JOURNAL * * *

Time ADDRESS Mode T ime PAGE RESULT

10:18AM [email protected] MailSMA 0'09" 2 - -

* * * JOURNAL * * *

10:17AM [email protected] MailSMQ 0'09" 2 OK

Time ADDRESS Mode Time PAGE RESULT



The network system administrator can confirm whether a sent mail has been received correctly or not. This confirmation is done in four steps. 1. Send request for confirmation of mail reception. Enable or disable this request with a user tool. 2. Mail reception (receive confirmation request) 3. Send confirmation of mail reception 4. Receive confirmation of mail reception The other party’s machine will not respond to the request unless the two conditions below are met: • The other party’s machine must support MDN (Message Disposition Notification). • The other party’s machine must be set up to respond to the confirmation request. To do this:

1) The ‘Disposition Notification To’ field is in the received mail header (automatically inserted in the 4th line in the upper table on the previous page, if MDN is enabled), and

2) Sending the disposition notification must be enabled. The content of the response is as follows: Normal reception: “Return Receipt (dispatched)” in the Subject line

Optional response (bit switch adjustment)

“Return Receipt (displayed)” in the Subject line

Error: “Return Receipt (processed/error)” in the Subject line



Handling Mail

- Handling Mail on the Send Side - When mail is sent, a “Disposition Notification To” notation is included in the header as a request for confirmation that the mail was received.

X-Mozilla Status : 0001

X-Mozilla Status2 : 00000000

Message-ID : <[email protected]>

Disposition-Notification-To : T.Suzuki <[email protected]>

Date : Tue, 28 Nov 2000 13:4203 +0900

From : T.Suzuki <[email protected]>

X-Mailer : Mozilla 4.73 [ja]C-CCK-MCD BDP jm-Sony 3 (Win95: U)

X-Accept-Language : ja

MIME-Version : 1.0

To : [email protected]

Subject : Mail Request for Reception Confirmation

Content-Type : text/plain: charset=iso-2022-jp

Content-Transfer-Encoding : 7bit



- Handling Mail on the Receive Side - Return Path: <>

Received : From fuser_01 ([133.139.157.20]) by dom1g.ricoh.co.jp (post office MTA V1.9.3 ID# 0100110-37392) with SMTP id AAA163 for<[email protected]>

Date : 28 Nov 2000 13:4236 +0900

X-Mailer : ICFAX Version 1.0

MIME-Version : 1.0

Content-Type : multipart/report: report-type=disposition-notification: boundary=”—ICFAX_000000EF48—“

To : T.Suzuki <[email protected]>

Message-ID : <[email protected]]>

From : [email protected]

Subject : From @81454771459”(“RICOH GTS)(Return Receipt)(dispatched)

X-Mozilla-status : 8001

X-Mozilla-Status2 : 00000000

X-UIDL : 20001128044713447.AAA163@fuser_01

This is a Return Receipt for the mail that you sent to “[email protected]”

Final Receipt: rfc822:fuser_01#dom1g.ricoh.co.jp

Original Message ID: <[email protected]

Disposition: automatic action/MDN-send-automatically: dispatched Respond Mail Text



Image Data Path

TIFF-F format

Reception

The software module [A] receives TIFF-F data from the memory [B] on the NIC board. Afterdecompression, the directory information for the data (resolution, file size) and image data aretransferred to the DCR buffer [C] in blocks. The data is then MH compressed.

The MH compressed image data in the DCR buffer is decompressed to bitmap data in the QPCR30[D] and transferred to the line buffer [E]. The data is MMR compressed in the QPCR30 then stored inthe SAF.

Memory

TIFF-FCompression

andDecompression

Module

DCRBuffer

LineBuffer

SAF

NIC FCE

Software MH MMR

QPCR30 QPCR30

BITMAP

H132D564.WMF

[B] [A] [C] [E]

[D]



Transmission

Data from the SAF data is decompressed into bitmap data in the QPCR30 and stored in the linebuffer. Then, it is MH compressed in the QPCR30 and transferred to the DCR buffer.

The software module makes a TIFF-F formatted file with directory information from the image data,then transfers this file to the memory on the NIC board.

NOTE: The TIFF (Tagged Image File Format) was developed by Aldus and Microsoft as anextensible common file format for the exchange of image files.In order to increase the portability of TIFF files, various classes of TIFF files have beendefined in order to clarify the requirements of readers and writers to ensure compatibility.Class F TIFF files are used for the exchange of fax images and are a subset of Class B (bi-level or black & white) TIFF images.MH, MR, and MMR compressions can be used to make a TIFF-F file.

Memory

TIFF-FCompression

andDecompression

Module

DCRBuffer

LineBuffer

SAF

NIC FCE

Software MH MMR

QPCR30 QPCR30

BITMAP

H132D565.WMF



DCX format

Reception

The software module [A] receives DCX data from the memory [B] on the NIC board. The DCX file isdivided into PCX images (one PCX image for each page). The data is decompressed into bitmapdata, then transferred to the line buffer [C].

The data is MMR compressed in the QPCR30, and stored in the SAF [D].

Memory

DCXCompression

andDecompression

Module

LineBuffer

SAF

NIC FCE

Software MMR

QPCR30

BITMAP

H132D566.WMF

[B] [A] [C] [D]



Transmission

Data from the SAF is decompressed into bitmap format in the QPCR30, and stored in the line buffer.The software module makes PCX and DCX data and headers and transfers these to the memory onthe NIC board.

NOTE: The DCX format was developed by Microsoft. It is an enhancement to the PCX format whichallows multi-page images.

Memory

DCXCompression

andDecompression

Module

LineBuffer

SAF

NIC FCE

Software MMR

QPCR30

BITMAP



Troubleshooting Procedures

OverviewTo resolve problems, a basicunderstanding of networking is required.

The drawing shows the route used for thevarious features used by this machine.

• LAN fax tx: $-#• 200-dpi printer: $• 200-dpi scanner: &-%• Autorouting: #-&-%• Forwarding: #-&-%• Internet fax (paper to paper): &-(• Internet fax (paper to PC): &-(• IC Fax Monitor: $• IC Viewer: On PC

only

NIC FAX Overview

PSTN

NIC FAX

#

Mail ServerG3 FAX

Client PC

NIC FAXMail Server

Client PC

Internet

$ %

& (

H132T511.WMF



Troubleshooting proceduresUse the following procedures to determine whether the machine or another part of the network iscausing the problem.

CommunicationRoute

Item Action Remarks

1. Connection withthe LAN

• Check that the LANcable is connected tothe machine.

• Check that the LEDs onthe NIC board and thehub are lit.

General LAN

2. LAN activity • Check that otherdevices connected tothe LAN cancommunicate throughthe LAN.

# G3communication

Refer to G3 faxtroubleshooting



CommunicationRoute

Item Action Remarks

1. Com Redirector • Check the modemsettings in Windows 95

• Check the port setting inWindows 95

• Make sure that the IPaddress registered inthe machine is the sameas the address stored inCom Redirector.

• Is the target NIC faxrunning?

• Is the modem set up inWindows 95 controlpanel set up the sameway as described in theoperation manual?

• Are the printerproperties in Windows95 control panel createdby the fax applicationsoftware set up as in theoperation manual?

2. Application faxsoftware

• Check the transmissionport setting.

• Check whether a PSTNaccess number isrequired.

• Refer to the operationmanual for theapplication.

$ Between NICFax and PC

3. Network settings onthe PC

• Check the Windows 95network settings on thePC.

• Is the IP addressregistered in the TCP/IPproperties in theWindows 95 networksetup correct? Checkthe IP address with theadministrator of thenetwork.



CommunicationRoute

Item Action Remarks

4. Check that PC canconnect with themachine

• Use the “ping”command on the PC tocontact the machine.

• At the MS-DOS prompt,type ping then the IPaddress of the machine,then press Enter.

5. LAN settings in themachine

• Check the LANparameters

• Check if there is an IPaddress conflict withother PCs.

• Use “LAN parameters”in service function 20.

• If there is an IP addressconflict, inform theadministrator.

1. E-mail applicationsoftware

• Use the application tocheck if transmissionand reception arepossible withdestinations other thanthe NIC fax machine.

• When an error messageappears in theapplication, solve it first.

• Inform the LANadministrator of theproblem so that it can bedealt with.

% Between PCand e-mailserver

2. Network settings onthe PC

• Check the PC’sWindows 95networksettings.

• Is the IP addressregistered in the TCP/IPproperties in theWindows 95 networksetup correct? Checkthe IP address with theadministrator of thenetwork.



CommunicationRoute

Item Action Remarks

3. E-mail account onthe server

• Make sure that the PCcan log into the e-mailserver.

• Check that the accountand password stored inthe server are the sameas in the machine.

• Ask the administrator tocheck.

4. E-mail server • Make sure that the clientdevices which have anaccount in the servercan send/receive e-mail.

• Ask administrator tocheck.

• Send test e-mail with themachine’s own numberas the destination. Themachine receivesreturned e-mail whenthe communication isperformed successfully.

& Betweenmachine and e-mail server

1. LAN settings in themachine

• Check the LANparameters

• Check if there is an IPaddress conflict withother PCs.

• Use “LAN parameters”in service function 20.

• If there is an IP addressconflict, inform theadministrator.



CommunicationRoute

Item Action Remarks

2. E-mail account onthe server

• Make sure that themachine can log into thee-mail server.



& Betweenmachine and e-mail server




( Between e-mailserver andinternet

1. E-mail account onthe Server

• Make sure that the PCcan log into the e-mailserver.





CommunicationRoute

Item Action Remarks




3. Destination e-mailaddress

• Make sure that the e-mail address is actuallyused.

• Check that the e-mailaddress contains noincorrect characterssuch as spaces.

4. Router settings • Use the “ping”command to contact therouter.

• Check that otherdevices connected tothe router can sent dataover the router.

• Ask the administrator ofthe server to check.



CommunicationRoute

Item Action Remarks

5. Error message by e-mail from thenetwork of thedestination.

• Check whether e-mailcan be sent to anotheraddress on the samenetwork, using theapplication e-mailsoftware.

• Check the error e-mailmessage.

• Inform the administratorof the LAN.



Symptoms For TroubleshootingInternet fax machines use procedures which are not the same as the fax machines we are familiarwith. The following can help solve problems in the field.

Decoding error during reception (1)

-- Possible Cause -When the machine receives e-mail with attached files that are not in TIFF-F or DCX format, adecoding error occurs because the machine cannot decode the files. The error occurs even if a textfile is attached.

- Explanation/Action -ITU-T and IETF require a TIFF-F formatted file to be attached for an Internet fax message. Thesender should send the e-mail again, with a TIFF-F formatted file attached.

Decoding error during reception (2)

- Possible Cause -The received e-mail has an attached file that has an unsupported resolution or page size.Messages of up to A4 width and up to 200 x 200 dpi resolution can be received.

- Explanation/Action -ITU-T and IETF specify a maximum size of A4 width for an attached file. The sender should resendthe e-mail, with an A4 size file attached. The paper size is not negotiated during Internet faxhandshaking.



E-mail Transmission with Incorrect LAN Parameters

(The machine can send e-mail even though the host name and domain name are not stored in themachine’s LAN parameters.)

- Possible Cause -During transmission to the SMTP server, the host name and domain name stored in the machineare used in the argument of the SMTP “HELO” command. However, the SMTP server can receivethe "HELO" command without the argument, so the machine does not check whether the hostname and domain name are stored.

- Explanation/Action -At installation, the host name and the domain name are not required if they are unknown at thetime. If incorrect names are stored, the SMTP server does not accept the HELO command and themachine cannot send e-mail to the SMTP server. Then, the machine fails to resend the correctnumber of times and prints an e-mail transmission error report.



Error in the first part of the e-mail transmission procedure

- Possible Cause -There is no domain name in the destination e-mail address (e.g., “123” is used instead of an e-mailaddress).

- Explanation/Action -When an e-mail address is sent to the SMTP server without a domain name (the address is blank isafter the “@” symbol), the server searches for the same user name in the local server. The serverfails to find the user name then the transmission is rejected in accordance with SMTP procedures.This is done in the first part of the e-mail transmission SMTP procedure.

NOTE: The following describes what happens if the domain name of thedestination is correct but the user name of the destination is incorrect.

1) When an e-mail with a domain name which is different from the localdomain name is sent, the SMTP server accepts the transmission andforwards the e-mail to the next SMTP server even if the user name ofthe e-mail address is incorrect. The local SMTP server cannot checkuser names in a remote server.

2) After that, the destination SMTP server checks the user name to see ifthat user has an account with the server. If there is no account, theserver creates an e-mail error report and sends it to the sender, and thisreport is printed by the machine.



LAN Parameters not listed after NIC Replacement

LAN parameters are not listed on the system parameter list after the NIC board is replaced.

- Possible Cause -Poor electrical contact between NIC board and machine

- Explanation/Action -When the machine does not recognize the NIC board, the NIC board does not initialized and LANparameters are not listed. The NIC board should be installed again.

Communication Error—E-mail Server Down

A communication error is indicated on the operation panel because the e-mail server is down.

- Possible Cause -The machine attempts to receive e-mail from the POP server by POP procedures at a regularinterval. When the machine cannot contact the server, a POP error occurs in the machine. A POPerror also occurs if the LAN cable is pulled out of the machine or if the network is down.When there is a POP error, a communication error is indicated on the display and thecommunication error LED is lit.

- Explanation/Action -The machine recovers from a POP error when either the next POP procedure or the next SMTPprocedure with the server is performed successfully. The user does not have to press the Stop key.



Transmission Error with Comma-separated Addresses

When a number of e-mail addresses separated with commas are stored for transmission, atransmission error occurs. (eg. [email protected], [email protected], [email protected])

- Possible Cause -An SMTP error occurs in the above case.

- Explanation/Action -When storing more than one e-mail address, the user must press the Yes key after storing eachaddress.


Group 3 Fax Communication Fax Troubleshooting Techniques

Fax Troubleshooting Techniques

Introduction

This section describes methods of solving commonly-occurring communication problems.Concerning copy quality and mechanical problem troubleshooting, specific troubleshootingprocedures for each model are given in the Service Manuals.

Basic Troubleshooting Philosophy

Discuss the problem and its symptoms with the customer in detail

There are many types of problem that can be encountered.

• Performance/operation errors

• Document jams (ADF problems)

• Copy paper jams

• Copy quality problems

• Communication problems



Understand when, where, how, and in what conditions the problem occurs. To do this, ask the userabout the following aspects of the problem and the machine's location of installation.

Location Office/warehouseClean/dustyTemperature and humidityPower source (stability, dedicated/shared)

Line Direct connection to the telephone company linePABX connectionDedicated/branchedTone dialling (DTMF)/pulse dialling

Settings DTMF/pulse dialCSI (full 20 digits)

Operation Auto dialling/manual diallingAuto reception/manual reception

Others Type of model at the other end



Study the symptoms by making communication tests (Tx and Rx)

- At the user's site -

Make tests with the terminal that the user was communicating with when the problem arose. Then,make tests with terminals that the user communicates with regularly. It is also helpful to call theseterminals from a telephone in order to find out about the line condition (echoes, noise, and other lineproblems can be heard).

After that, make tests with your test centre. Have your test centre observe the protocol sequence,modem rate, level, and line condition with an oscilloscope and other equipment.

- At the test centre -

Make tests with the user end at first. Then, make tests with the other end that the user wascommunicating with when the problem arose.

During these tests, observe the protocol sequence, etc.

Make up a drawing of the protocol sequence using these observations.

Try to adjust the terminal settings

Try to solve the problem by adjusting bit switch or RAM address settings in the machine.



Sources of Line Problems in Telephone Circuits

OverviewSources of problems affecting the quality of data transmission over the telephone network can beroughly classified into two groups, as shown below, in accordance with their character.

Constant sources These include transmission loss, attenuationdistortion, envelope delay, frequency deviation,echo, circuit noise, and non-linear distortion.

Unpredictable sources These include impulse noise, dropouts, phasehits, and gain hits.

It is necessary to consider the following characteristics of the telephone network when using datatransmission equipment.

• Separate calls between the same terminals may be connected along different paths in thetelephone network, thus causing differences in various transmission characteristics because ofthe difference in the connected links or types of exchange.

• Impulse noise, dropout and other types of interference having a great influence on datatransmission and telephone communication are unpredictable both in their occurrence and in theireffects.

• The characteristics of the communication network are continually being improved by theintroduction of new systems or equipment. However, the mixture of new and old switches andvarious types of transmission equipment makes transmission characteristics irregular.



The following pages contain explanations of some sources of line problems. First, however, it isimportant to understand some of the terminology concerning the relationship between the data signaland noise. The following diagram illustrates the most important terms that are used on the next fewpages.

The diagram covers a wide frequency spectrum. However, the frequency range of modems in typicalfax machines is only from 500Hz to 2900Hz.

Tshoot1.wmf



Another important term is the Signal to Noise ratio (S/N). To calculate the S/N (Signal to Noise) ratio,do the following.

1. Measure the level in dBm of the transmitted (or received) V21 protocol signal or V27/V29document data signal.

2. Measure the white noise level in dBm.

3. To calculate the S/N ratio (dB), subtract the white noise level from the signal level.

For example:

Received signal level = -25 dBmWhite noise level = -50 dBm

⇒ S/N ratio = -25 - (-50) dB= 25 dB

The S/N margin of a modem is the S/N ratio below which the modem cannot separate the data signalfrom the noise.



Transmission LossTransmitted signals are attenuated by the resistance of the telephone circuit, mainly due to the longcopper cables. This weakening is known as transmission loss. Different sections of the circuit causedifferent amounts of transmission loss.

Attenuation DistortionSignal levels at high frequencies level may bereduced by resistance and the length of the line.Cable equalizers can be used to counteract thisproblem. However, if the cable equalizer isovercorrected, the machine may be forced to fallback to a lower modem rate during training.

Tshoot2.wmf



White Noise and Circuit NoiseCircuit noise includes power supply noise and noise generated by components such as tubes andtransistors.

White noise is the major contributor to the background noise level at the receiving end and is thebasic parameter used to determine the S/N margin of the modulation system.

Data errors may be caused by a low S/N ratio but this is not the only cause of data transmissionerrors. Data transmission over a circuit with an S/N ratio that exceed the S/N margin for the modemis susceptible to interference such as impulse noise or envelope delay.

Impulse NoiseImpulse noise is unpredictable in generationinterval and in amplitude. Therefore, theanalysis of its generation, the method ofmeasurement, and the evaluation of the effecton data signals are different from circuit noise.

In data communication, impulse noise mayalter the data signal, possibly causing anerror.

The diagram shows typical impulse noiseclicks caused by a step-by-step switch. These clicks occur at irregular intervals.

Tshoot3.wmf



Time Unit SignalTime unit signals are generated by the trunk exchangeswitchboard on the calling side and can be observed atthe Tip and Ring (L1 and L2) terminals on the faxmachine.

The drawing shows an example of this type of signal.The charge billed to the caller is determined by thenumber of pulses generated by the trunk exchangeswitchboard.

Pulses of long wavelengths cause no problems, butinterference within the voice band may cause errors tothe data.

Tshoot4.wmf



Dropouts And Gain HitsA dropout is a sharp decline of the receivedsignal level in a relatively short time. This mayhave been caused by a line problem, a fault ina terminal, or another cause.

In the ITU-T recommendations, a dropout is adrop in level of 6 dB or more over a durationof between 1 ms and 1 minute.

A gain hit is a sudden increase or decrease insignal level. A dropout is a special case ofgain hit, where the signal may become almostundetectable.

Envelope DelayVoice, data, and other transmitted electric signals take some time to reach the receiving side. Thereceived signal may be out of phase with the transmitted signal. The phase difference is known asenvelope delay.

If different envelope delays occur with different carrier frequencies, this is known as envelope delaydistortion.

Generally, the attenuation and phase characteristics of the transmission line vary depending on thesignal frequency.

Gain hit

Line problemor

gain hit

10

6

5

0

Dropout

Duration0.5

[ms]1

[ms]1.5

[ms]1

[min]

orgain hit

Impulsenoise

CCITT definition of dropouts and gain hitsTshoot5.wmf

Level drop (dB)



Effects of Line Problems on Copy Quality

The two major effects of line problems on copy quality are:

• Missing lines, causing shrinkage in the sub scan direction

• Cutoff, with the data abruptly stopping in the middle of the page.

These are illustrated in the following set of diagrams.

OriginalTshoot6.wmf

Missing LinesTshoot7.wmf

CutoffTshoot8.wmf



Test Procedures

GeneralThe diagram shows the basic testingprocedure when dealing with line noise.

OK

OK

OK

Increase the Tx level

Use the cable equalizer,

Use MH coding

Drop the modem rate

NG

NG

NG

Change the error threshold

Check the other terminal

Check for noise

Check the Tx level

Change the trainingerror tolerance

Is it a Tx or an Rx problem?

Tx

Check for noiseNG

Use MH coding/dropthe modem rate

OK

Rx

or ask the other party toincrease their Tx level

Check the Rx leveland the S/N ratio

Tshoot9.wmf



Other problems that may occur are as follows:

• If the T1 timer runs out before a CED signal comes in from the other end, increase the T1 time.This problem may occur on international calls.

• If there are echoes on the line, switch on the echo countermeasure.

• If the other terminal is a fax board or other PC controlled device, you may have to change thereconstruction time of the 1st line from 6 s to 10 s.

The adjustments mentioned above can be made in most models by bit switch. Some parameters canbe changed using dedicated transmission parameters; these allow a technician to change aparameter for a particular destination only (for example, if echoes are frequently encountered whendialling a particular destination). For details on a particular model, refer to the Service Manual for thatmodel.



Decibel Level MeasurementSignal levels are measured in decibels. The decibel is the logarithm of the ratio of the output signalpower (P1) to the input signal power (P2).

dB = 10 log10(P1/P2)

Logarithms are the most effective way to measure signal levels because:

• The ear responds to sound in a roughly logarithmic manner.

• The ratio between two levels, such as the S/N ratio, can be obtained simply by subtracting the twosignal levels, instead of dividing.

For measuring signal levels on telephone circuits, a standard reference value of 1 milliwatt (mW) istaken for P2. Signals measured in this way are quoted in dBm (decibels relative to 1 mW).

dB = 10 log10 (Signal Power [in mW]/1 mW)

A signal of 1 mW is quoted as 0 dBm. Each telephone circuit contains a 0 dBm reference point at theoutput of the telephone exchange at the sending end of the circuit. This reference point may also bereferred to as the zero transmission level point (0TLP).

Signal levels measured at any point in a circuit can be measured in dBm. For example, if a signal isdelivering 100 mW of power, its level is 20 dBm. However, if you wish to quote relative gain or lossbetween two points in the circuit, the value must be stated in the dB unit. Also, ratios of signal levels,such as the S/N ratio, are quoted in dB.



To measure signal levels, you can use an oscilloscope. For example, to measure the level of signalsentering and leaving the fax machine, connect the oscilloscope across the Tip and Ring (L1 and L2)terminals on the fax machine. Measure the peak-to-peak level in millivolts (mVp-p) and convert it todBm using the following table.

dBm mVp-p dBm mVp-p10 6.931 -11 0.6179 6.176 -12 0.5518 5.506 -13 0.4927 4.907 -14 0.4386 4.372 -15 0.3905 3.897 -16 0.3484 3.473 -17 0.3083 3.097 -18 0.2772 2.760 -19 0.2461 2.458 -20 0.2210 2.192 -22 0.175-1 1.954 -24 0.139-2 1.742 -26 0.110-3 1.553 -28 0.088-4 1.383 -30 0.071-5 1.233 -32 0.054-6 1.097 -34 0.042-7 0.978 -36 0.034-8 0.874 -38 0.028-9 0.777 -40 0.023-10 0.693



Signal levels vary from country to country in accordance with local regulations. However, transmittedsignals are usually between 0 and -15 dBm, and received signals are normally in the region of -20 to-34 dBm.

CAUTION: Do not place grounded test equipment across the Tip and Ring (L1 and L2) terminals.This will cause an imbalance in the phone line, leading to erroneous readings or evenline disconnection. If the test equipment is grounded, bypass the ground by plugging thethree-pin plug into an adapter that converts the plug into a two-pin plug (do not cut off theground plug of the power cord).

Back-to-back TestsIf you wish to test communication between two fax machines directly, without having to connect themthrough any type of exchanger or switching device, you can carry out a back-to-back test. Theprocedure is as follows.

1. In both of the machines, enable back-to-back test mode. This is normally done by adjusting a bitswitch; refer to the Service Manual for the machine for details.

2. Connect the two machines together with a line cord. Do not connect a switching device betweenthe machines.

3. Place a document in the feeder of one of the machines.

4. Press the Start key on both machines at about the same time.

5. After finishing the test, put the back-to-back test mode bit switch back to the default setting in bothmachines.



Note

Normally, a battery must be connected somewhere in the circuit between the two machines to supplyline voltage. This voltage simulates the voltage supplied by the telephone network. However, somemachines have a circuit to generate this voltage. If both machines in the test have such a circuit, thenactivate the circuit in both machines before starting the test, and deactivate it after the test. There isno need to connect a battery. Refer to the model's Service Manual for details on how to activate thiscircuit for each model.


Group 3 Fax Communication Common Fax Features

Common Fax Features

This section contains technical descriptions of some fax features that are common to most models.

Auto Service Calls

Service Call ConditionsThe machine makes an automatic service call to the service station telephone number when an errorcode occurs. The error codes specified for this feature may differ from model to model.

Periodic Service CallThe periodic service call notifies the condition of the machine to the service station. The call is madeperiodically at a time interval programmed in RAM.

The Call Service indicator does not light for a periodic service call, so that the machine can beoperated normally after it has sent the service call.

PM CallIf PM call is enabled, the machine will make an automatic service call when the PM counter reachesthe PM call interval in RAM.

The Call Service indicator does not light for a PM service call, and the machine can be operatednormally after it has made the service call.



Excessive Jam Alarms

6

1

2

3

4

5

03224168 64564840 72

16

8

03224168 64564840 72

4

12

48

16

32

03224168 64564840 72

JAM

NO-JAM1

NO-JAM2

CALL Threshold (=6)

DEC Threshold (=16)

CLR Threshold (=48)

OR

16 pages fed without jam 16 pages fed without jam 16 pages fed without jam

48 pages fed without jam

Decrement

DecrementReset to

zero

H516d535.wmf



The excessive jam alarm automatically notifies the service station when the machine's scanner orprinter frequently has jam problems.

Each type of jam has three counters allocated to it (JAM, NO-JAM1, NO-JAM2). Each of thesecounters has a threshold value (CALL, DEC, and CLR respectively; these can be adjusted.) Themachine uses these counters to monitor jams as follows.

• JAM: Jam counter used to place a service call• NO-JAM1: Counter used for JAM counter decrement• NO-JAM2: Counter used for clearing the JAM counter

Each time a jam occurs: The JAM counter is increased by 1, and NO-JAM1 and NO-JAM2 are bothset to zero. When JAM reaches CALL (6 by default), the machine sends an Auto Service Report witha System Parameter List.

If a sheet of paper is fed without a jam occurring: NO-JAM1 and NO-JAM2 are both incrementedby 1. When NO-JAM1 reaches DEC (16 by default), NO-JAM1is set to zero, and JAM isdecremented by 1. When NO-JAM2 reaches CLR (48 by default), NO-JAM2 and JAM are both resetto zero.

The CALL, DEC, and CLR thresholds can be adjusted for each type of jam.

The Call Service indicator does not light for an excessive jam alarm, and the machine can beoperated normally after the automatic service call has been made.

Effective Term of Service CallsIf a time limit for the effectiveness of service calls is programmed, the machine stops makingautomatic service calls after the time limit.



Fax On Demand

OverviewFax On Demand is a polling application with pre-recorded voice assistance. A caller can get one ormore fax messages in one polling operation using a DTMF tone sequence. A password (Remote ID)can be used to secure the information from unauthorized access.

CircuitExample: H515

MFCEMFDU

Voice A/DConverter

SCP

LPCEXIO-2(IC4)

HIC

DTMFReceiver

Microphone

Speaker

ModemNCU

FOD CardSRAM

(512kB)

Serial InterfaceBus Interface

Message Record

Playback Message Playback / Transmission



The machine can have several voice messages to instruct the caller. The voice messages arerecorded using the microphone, then the Voice A/D Converter on the MFCE converts them intodigital format and stores them in the SRAM inside the Fax On Demand card. When playing back amessage or transmitting it to a caller, the Voice A/D Converter converts the digitized message backto an analog voice message and sends it to the speaker or the NCU through the HIC on the MFDU.

The SRAM on the Fax On Demand card is backed up by a battery on the card.



Protocol

CNG

CNG

CNG

CED

NSF

DIS

Message"This is a fax service ... "

Tx Rx

Dial Ring Detection

Message"This is a fax service ... "

Tx Rx

Dial Ring Detection

" 1 "

" 5 "

" # "

Box No.Specified

Message

" # "

" # "

No Box No.Specified

Message"Press Start ..."

CED

NSF

DIS

DIS or NSF

CN

G/D

TM

F D

ete

ctio

n

CN

G/D

TM

F D

ete

ctio

n

H515D523 wmf



After ringing detection, the machine sends a pre-recorded message, and at the same time, starts todetect CNG signals or DTMF tones from the caller. The dedicated DTMF receiver on the MFDU isused to detect both CNG signals and DTMF tones.

If the machine detects CNG signals, the machine goes into fax reception mode. If the machinedetects DTMF tone signals, the machine then sends some more messages to instruct the caller whatto do. After the last message has been sent to the caller, the machine goes into fax transmissionmode.

Sometimes the machine might not detect DTMF signals while the machine is transmitting a voicemessage. To avoid this, the messages should instruct the caller to send DTMF signals after themessage has been finished.

While Fax On Demand is enabled, the machine disables receiving Transfer Request using DTMFtones, because it may use the same key sequence.



Line Type Change

When the machine is initially used only with the PSTN, the line type programmed with phonenumbers in Quick Dials and the Speed Dials is stored as PSTN G3.

Later, if the line connection is changed so that G3 is to be used only with the ISDN, thecommunication port for all stored Quick and Speed Dials must be changed to ISDN G3.

This feature allows the communication mode and port to be changed for all stored numbers at once.

Procedure:

1) Change the following data in RAM.

• Current line type setting• Line type to be used after this procedure

2) Turn the main switch off and on.

Then, the machine checks all phone numbers stored in Quick Dials, Speed Dials, AI Redial, andForwarding Stations. If the communication mode and the port setting for a number are the same asspecified for the “current line type setting” above, the machine changes these to the new setting.

Do not use this procedure if there are any files stored in the memory awaiting transmission.



Parallel Memory Transmission

Using memory transmission, normally the machine starts dialing after the document has beencompletely scanned. Using Parallel Memory Transmission, the machine starts dialing at the sametime the machine starts scanning. If the document has multiple pages, the machine scans them intomemory and sends them at the same time.

The following table shows the differences between normal memory transmission and parallelmemory transmission.

Memory tx Parallel memory tx

File Reserve Report Printed, if automatic reportprintout is enabled.

Not printed.

If the other terminal is busy Tries to resend the messagelater.

Continues scanning thedocument into memory, andtries to resend it later.

If transmission failed Tries to resend the remainingpages later.

Tries to resend the remainingpages later.

If memory overflows duringscanning

Stops scanning and erases allthe scanned pages frommemory, if the user agrees toerase them.

Stops scanning and hangs upthe communication whenmemory overflow is detected.Then erases all the scannedpages from memory without



notifying the user.

If a document jam occurredduring scanning

Stops scanning and deletes allthe scanned pages frommemory.

Stops scanning and hangs upthe communication when adocument jam is detected.

How and when the scannedmessage is erased frommemory

The complete message iserased after all the pages havebeen sent.

Each page is erased after thepage has been successfullysent.

Memory threshold to startscanning into memory

Depends on the setting ofcommunication switch 0D.H515 Default setting – 24kB

Depends on the setting ofsystem switch 10.H515 Default setting – 512 kB

Meaning of the stamp mark Successfully stored. Successfully stored.

Batch numbering (P. x/x) Enabled Not available unless the numberof pages is programmedmanually.

Using G4 transmission, parallel memory transmission is normally disabled because the transmissionspeed is much faster than the scanning speed.

Transmission using parallel memory transmission is about twice as long as normal memorytransmission (using an ITU-T #1 test chart).



However, if the document contains pages with complicated images or when sending a photodocument using halftone, using parallel memory transmission may be faster than normal memorytransmission.

If the user commonly sends this type of fax message, enable parallel memory transmission for G4transmission by changing system switch 11, bit 7 to 1.



Page Separation and Sub-scan Reduction

IntroductionIn fax machines that use cut paper (such as laser fax machines), there is a problem if the incomingmessage is longer than the copy paper. This section explains the settings that control how themachine deals with this problem.

The two techniques used are:

• Page separation: Printing the received page on two or more sheets of copy paper.

• Sub-scan reduction: Reducing the data in the sub-scan direction so that it will fit on the page. Thismeans that the image will appear to be squashed.

The methods used so far can be classified into two types (there is no special reason for having twodifferent methods). These will be described separately

• Method 1 (normally used in standalone fax machines)

• Method 2 (normally used in fax board options for digital copiers)



Method 1Example: H515

The process depends on whether reduction is enabled or disabled. This is a bit switch adjustment.

If reduction is disabled

Case 1: If the incoming page is up to x mm longer than the copy paper, the excess portion will notprint.

• The value of x is adjusted by bit switch. It can be between 0 and 15 mm.

Received message

Copy paperlength

x mm

Printout

H515dis1.wmf



Case 2: If the incoming page is more than x mm longer than the copy paper, the message is printedon more than one sheet of paper.

• The last few lines of the first page can be repeated at the top of the second page, or not (look atpoints A and B in the above diagram). This is another bit switch adjustment.

• A mark can be printed on incoming messages that have been printed on more than one page.

Received message

Copy paperlength

x mm

Printout (twopages)

AB

A

B

A

B

OR

A

P.1 P.1

P.2 P.2



If reduction is enabled:

Case 1: If the incoming message is more than 5 mm shorter than the copy paper, there is noreduction. This 5 mm is a fixed value.

Received message

Copy paperlength

5 mm

Printout

No reduction

H515en1.wmf



Case 2: If the incoming message is within 5 mm shorter than the copy paper and a certain maximumlimit, the page is reduced in the sub-scan direction.

• This maximum limit depends on the copy paper size, and the reduction ratio selected for that copypaper size. (Example: For A4 at a reduction ratio of 4/3, this limit is 388.8 mm.) Beyond thismaximum limit, the incoming data cannot be reduced to fit on the copy paper.

• The reduction ratio for each copy paper size can be adjusted with bit switches.

Received message

Copy paperlength

Limit

Printout

Reduced

H515en2.wmf



The following tables show the limits for each copy paper size. These have been the same in allrecent models.

USA Models

- Resolution: lines/mm -

Copy Printable Page Maximum LimitType Length Ratio = 4/3 Ratio = 8/7 Ratio = 12/11Letter 279.2 mm 365.2 mm 313.0 mm 298.7 mmLegal 355.6 mm 467.0 mm 400.3 mm 382.1 mm

- Resolution: lines/inch -

Copy Printable Page Maximum LimitType Length Ratio = 4/3 Ratio = 8/7 Ratio = 12/11Letter 279.4 mm 365.8 mm 313.4 mm 299.2 mmLegal 355.6 mm 467.4 mm 400.6 mm 382.3 mm



Europe/Asia Models

- Resolution: lines/mm -

Paper Printable Page Maximum Reducible Incoming Page LengthType Length Ratio = 4/3 Ratio = 8/7 Ratio = 12/11

A5 Sideways 147.8 mm 190.1 mm 162.9 mm 155.3 mmA4 296.9 mm 388.8 mm 333.2 mm 318.2 mmF4 330.1 mm 433.2 mm 371.2 mm 354.3 mm

- Resolution: lines/inch -

Paper Printable Page Maximum Reducible Incoming Page LengthType Length Ratio = 4/3 Ratio = 8/7 Ratio = 12/11

A5 Sideways 147.8 mm 190.2 mm 163.4 mm 155.7 mmA4 296.9 mm 388.9 mm 333.5 mm 318.3 mmF4 330.2 mm 433.3 mm 371.3 mm 354.6 mm



Case 3: If the incoming message is longer than the maximum limit, it is not reduced. It is printed onmore than one sheet of paper, in a similar manner to case 2 when reduction is disabled (see above).

• The last few lines of the first page can be repeated at the top of the second page, or not (look atpoints A and B in the above diagram). This is another bit switch adjustment.


Received message

Copy paperlength

Limit

Printout (two pages); no reduction

AB

A

B

A

B

OR

A

P.1 P.1

P.2 P.2



Bit Switch Summary

- General -

• Reduction, enable/disable

- If reduction is disabled -

• Page separation threshold• Repetition of the last few lines of the previous page at the top of the next page• Page separation mark

- If reduction is enabled -

In addition to the above three switches for when reduction is disabled, there is the following:

• Reduction ratio for each copy paper size

Each paper size can have a separate reduction ratio. Example: H545, Printer switches 04 and 05In each of the two bit switches, there is one bit for each possible paper size. The combination ofthe bit settings determines the ratio for that paper size.

Bit No. Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0Switch

No.Not used Not used Legal F4 A4 Letter Not used A5

sidewaysSw 04 0: 4/3 1: 4/3 0: 8/7 1: 12/11Sw 05 0: 0: 1: 1:

For example, bit 3 in switches 04 and 05 determine the reduction ratio for A4.If bit 3 is 1 in switch 04 and 0 in switch 05, the reduction ratio for A4 is 4/3.



Method 2Example: A891

The process depends on whether reduction is enabled or disabled. This is a bit switch adjustment.

If reduction is disabled

Case 1: If the incoming page is shorter than the copy paper length + x mm but longer than the paperlength - 4 mm, the part of the image after paper length - 4 mm will be lost

• The value of x is adjusted by bit switch. It can be between 0 and 15 mm. It is known as the ‘pageseparation threshold’.

• The 2 mm gaps at the leading and trailing edges depend on the leading and trailing edge marginsettings.

Paper length - 4 mm

WithinPaper length +x mm

Not printed

Received Image Printed Image

A891dis1.wmf



Case 2: If the image is longer than the copy paper length + x mm, it is printed on more than onesheet of paper.

• The last few mm of the first page can be repeated at the top of the second page, or not (note therepetition or non-repetition of A in the diagram). This is another bit switch adjustment.

• The amount of repeated data can also be adjusted by bit switch. In the above diagram, it is 10 mm.The bottom of the repeated part of the data is always at ‘paper length – 4 mm. If the amount ofduplicated data is 10 mm, then the top of the data is at ‘paper length – 14 mm’.


Paper length - 4 mm

Paper length - 14 mm

Received ImagePrintout, withduplication

AA

A

A

Printout, with noduplication

A891dis2.wmf



If reduction is enabled:

Case 1: If the incoming message is more than 4 mm shorter than the copy paper, there is noreduction. This 4 mm is a fixed value.

Received message

Copy paperlength

4 mm

Printout

No reduction

A891en1.wmf



Case 2: If the incoming message is within 5 mm shorter than the copy paper and a certain maximumlimit, the page is reduced in the sub-scan direction.

• This maximum limit depends on a bit switch setting. Typically, it can be between 0 and 155 mm,with a default setting of 20 mm. This limit is also known as the ‘page separation threshold’ (there isa different threshold for when reduction is disabled).It is used for all paper sizes.

• The size of the limit determines the maximum reduction ratio that is used. A larger value allowsgreater reduction. However, the actual reduction that is used depends on the length of themessage; the message is always reduced to fit on the copy paper exactly, so the ratio will differfrom case to case.

Received message

Copy paperlength

Limit

Printout

Reduced

A891en2 wmf



Case 3: If the length of the incoming message exceeds the maximum limit, a feature called reductionrate equalization comes into play. If this is switched off, the incoming page is printed on more thanone page. However, reduction is only used in the final page.

The diagram shows an example where duplication is enabled, the amount of duplicated data is 10mm, and the maximum limit is 20 mm. Again, the maximum reduction rate for the final page dependson the value of this limit, and the actual reduction rate used depends on the amount of data that hasto fit on the final page of copy paper.

Paper length - 4 mm

Paper length - 14 mm

Received Image Printout

AA

A

Betweenpaper length - 4 mm

andpaper length + 20 mm

Notreduced

Reduced

A891en3.wmf



1. The data up to [page length - 4 mm] will be printed on page 1, without reduction.

2. The last 10 mm of this data will be repeated at the top of the next page (this length can be can beadjusted or repetition can be switched off).

3. The remaining data will be printed on page 2, with reduction, if it is within [paper length – 4 mm][paper length + 20 mm]. The 20 mm limit can be adjusted with bit switches.

4. If it is longer than this, page separation is done again. Data up to [paper length - 4 mm] will beprinted on page 2, without reduction.

5. The process for page 3 and subsequent pages will repeat from step 2.



Case 4: If the length of the incoming message exceeds the maximum limit, and reduction rateequalization is on, the incoming page is printed on more than one page. Reduction is used on allpages of the output, at the same reduction ratio.

The diagram shows an example where duplication is enabled, the amount of duplicated data is 10mm, and the maximum limit is 20 mm.

Received Image Printout

AA

AB

Reduced

Reduced

A

Within (paper length x 2)+ 20 mm

A must equal B

A891en4.wmf



1. The machine determines how many pages will be needed to print the message, taking thefollowing into account:

The final page (n) is such that the received image length is within (paper length x n) + 20 mmThe data must be reduced to fit on pages of length (paper length - 4 mm), with an equalreduction rate for each page.The last 10 mm of the previous page will be repeated at the top of the next page (this length canbe adjusted or repetition can be disabled).

2. The machine prints all the pages, at the same reduction rate.



Bit Switch Summary

- General -

• Reduction, enable/disable

- If reduction is disabled -

• Page separation threshold for when reduction is disabled• Repetition of the last few mm of the previous page at the top of the next page• Amount of repeated data (if repetition is enabled)• Page separation mark• Page separation, on/off

- If reduction is enabled -

• Page separation threshold for when reduction is enabled• Reduction rate equalization, on/off• Repetition of the last few mm of the previous page at the top of the next page• Amount of repeated data (if repetition is enabled)• Page separation mark• Page separation, on/off

Note that there is a switch to disable page separation. If page separation is disabled, any messagerequiring this feature is kept in the SAF memory (using Substitute Reception) until a paper size isinstalled that can be used to print the message without page separation.


Process Control

Basic Concepts

Process control is a system that automaticallychanges machine processes to compensate forchanges in the environment or the machinecondition. The objective of process control is tostabilize the quality of image output. The practicalresult is a decrease in the frequency of servicecalls, thus increasing customer satisfaction anddecreasing service cost.

The box to the right lists the machine conditionsthat process control compensates for.

In this section (Basic Concepts) we will take an overall look at process control. Then we will look atthe details of process control using several example machines. We will look at two OPC analogmachines—one using a potential sensor (model A095) and one using a V sensor (model A074).Then we will study an OPC digital system (model A229). Finally, we will look at selenium drumanalog systems (models A029 and A058).NOTE: Unlike other parts of the Core Technology Manual, we don't pull out and compare example sub-units of

process control but instead look at the process control systems of the example machines in their entirety.This is because process control components are interactive and best studied as a whole.

Basic ConceptsOPC Analog SystemsOPC Digital SystemsSelenium Analog Systems

Target Machine Conditions

! Dirty optics

! Exposure lamp deterioration

! Dirty charge corona wire/grid

! Change of drum sensitivity

! Deterioration of developer


PROCESS CONTROL Basic Concepts

Latent Image Control and Image Density Control

This illustration represents a copier modelthat uses two process control methods.One compensates for variation in the drumpotential (latent image control) and theother controls the toner concentration andtoner supply amount (image densitycontrol).

All process control components affect oneor the other (or both) of these methods.



Latent Image Control

The figure shows the changes of the drum potential during the copy process.

VO Drum potential just after charging the drum.

VD (Dark Potential) Drum potential just after exposing the black pattern (VD pattern)

VL (Light Potential) Drum potential just after exposing the white pattern (VL pattern)

VR (ResidualVoltage)

Drum potential just after the exposure of the erase lamp.



Image Density Control

The following sensors control image density.

• Toner density sensor (TD sensor)• Image density sensor (ID sensor)

Data from the TD sensor is used to keep the toner concentration in the developer at a constant level.However, the image on the OPC drum varies due to the variation of toner chargeability (influenced bythe environment) even if the toner concentration is constant. By the ID sensor compensation, tonerconcentration is changed to keep the image density on the OPC drum constant.

The following items are controlled to maintain a constant copy image density:

• Toner supply clutch on time• Toner supply level data (VREF) of the TD sensor

NOTE: Some machines do not have a TD sensor and use only an ID sensor forimage density control.



Terminology and Abbreviations

The following list explains the meaning of some of the terms and abbreviations used when describingprocess control.

VO (Original Potential) The drum potential after the drum is charged.

VD (Dark Potential) The drum potential in black image areas after exposure. StandardVD is the potential measured after exposing a black pattern.

VL (Light Potential) The drum potential in white image areas after exposure. StandardVL is the potential measured after exposing a white pattern.

VR (Residual Voltage) The drum potential after the drum has been exposed by the eraselamp.

Potential Sensor A sensor used to measure the strength of the charge on the OPCdrum surface (drum potential).

VL Pattern A standard white pattern used for reference. On some machinesthe VL pattern is actually a light gray tone rather than pure white.

VD Pattern A standard black pattern used for reference.

ID Sensor A photosensor that measures the image density (reflectivity) of thedrum and of a test pattern (ID sensor pattern). The output of thissensor is used to control toner supply.



ID Sensor Pattern A standard pattern that is exposed and developed for sensing bythe ID sensor.

VSG The ID sensor output when checking the erased drum surface.

VSP The ID sensor output when checking the ID sensor pattern image.

VLAMP Exposure lamp voltage.

VB or VBB Development bias.

TD Sensor Toner density sensor—it measures the concentration of toner inthe developer.

VREF A targeted control reference for the TD sensor. When VTDbecomes too low, toner is added to the developer to bring VTDback to the VREF value.

VTD, VT, or VOUT The output voltage of the TD sensor.

V Sensor A reflective photosensor similar to the ID sensor that is used toindirectly measure the drum potential. It was used prior to thedevelopment of the potential sensor system and will be found inearlier models using process control.

VG or VGRID Charge corona grid potential.



VH (Halftone Potential) A standard halftone drum potential. This value is used for laserpower adjustment in the process control system of some digitalproducts.


PROCESS CONTROL OPC Analog Systems

OPC Analog Systems

Model A095—Process Control Using a Potential Sensor

After long usage following installation or a PM, drum potential will gradually increase due to thefollowing factors:

• Dirty optics or exposure lamp deterioration• Dirty charge corona casing and grid plate• Change of the drum sensitivity

In this copier, the change in drum potential is detected by the drum potential sensor and the followingitems are controlled to maintain good copy quality.

• The grid bias voltage• The exposure lamp voltage• The development bias voltage.

A drum thermistor detects the drum temperature and this data is also used to control the abovevoltages. It is impossible to explain simply because it is controlled by methods developed in ourlaboratories using an artificial neural network.



Process Control Data Initial Setting

The flow chart shows the stepsperformed when turning on the machinewhile the hot roller temperature is below100°C. This initializes all the processcontrol settings.



Latent Image Control

Drum Potential Sensor Calibration

The drum potential sensor [A] detects thestrength of the electrical potential on the drum.The output of the potential sensor depends onthe strength of the electrical field on the drum.Since environmental conditions, such astemperature and humidity affect sensor output,the sensor output data is recalibrated duringeach process control initialization.

The High Voltage Control PCB [B] has tworelay contacts. Usually RA602 grounds thedrum. However, during the initial setting, themain PCB turns RA601 on and RA602 off andapplies the recalibration voltage to the drum shaft.By measuring the output of the drum potential sensor when –100 V and –800 V are applied to thedrum, the sensor output data is calibrated automatically. (The machine recognizes the relationshipbetween actual drum potential and the potential sensor output.) To prevent toner attraction duringpotential sensor calibration, an equivalent bias voltage (-100 and -800) is applied to the developmentrollers.



VR Measurement

The relationship between the drumpotential and the original density isillustrated at right. To get consistentcopy quality throughout the drum’slife, this relationship must bemaintained. Since this relationshipchanges due to various factors to theone represented by the dotted line,compensation is required. Factorscausing these changes occur in theoptics and charge sections and indrum sensitivity. The residual voltage(VR) cannot be compensated even ifexposure lamp voltage is increased.Therefore, the VR change has to becompensated by other means.

After drum conditioning the maincontrol board turns on the erase lamps. Then the potential sensor checks the drum potential. Thismeasured drum potential is in fact VR. This VR is used as the standard for the VD and VL corrections.

NOTE: In the figure above, the residual voltage (VR) for the new drum is 0V. Actually, there is someresidual voltage even on a new drum.



VD Correction

The drum potential just after the blackpattern (VD Pattern) is exposed (VD: DarkPotential) tends to lower during drum life dueto a decrease in the drum’s capacity to carrya charge. To check the actual VD, the firstscanner moves to the home position and theVD pattern (Black) mounted on the bottom ofthe exposure glass bracket, is exposed onthe drum.

The main control board measures VDthrough the drum potential sensor andadjusts it to a target value by adjusting thegrid bias voltage (VGRID). On the other hand,there is a change of the drum residualvoltage (VR), so that the target VD voltage iscompensated as follows:

Target VD Value: VD = VR + (–770)

The adjusted grid bias voltage (VGRID) is kept in memory until the next process control data initialsetting.



VL Correction

Dirty optics and exposure lamp deteriorationdecreases the intensity of the light that reachesthe drum. In addition to this, the drum sensitivityalso changes during the drum’s life. These factorschange the drum potential just after white patternexposure (VL: Light Potential).

To check the actual VL, the lens moves to the VLpattern check position. The VL pattern (White)mounted on the bottom of the exposure glassbracket is exposed on the drum. The main controlboard measures VL through the drum potentialsensor and adjusts it to a target value by adjustingthe exposure lamp voltage (VLAMP). The residualvoltage (VR) change also affects VL, so thatVL’s target voltage is compensated as follows:

Target VL Value: VL = VR + (–140)

The adjusted exposure lamp voltage (VLAMP) isstored in memory until the next process controldata initial setting.



VR Correction

Potentials (VR, VD, VL) are monitored bythe potential sensor. (This is done onlywhen the fusing temperature is less than100°C after the machine is turned on.)

During the check cycle, the VD and VLpatterns are exposed and the drumpotential of the area exposed by eachpattern is checked by the potential sensor.

Compare the curve of the VD and VLcompensated drum potential with thecurve of the new drum, they are parallelbut the compensated potential is stillhigher (VR) than the new drum potential.To prevent dirty backgrounds due toincreased residual potential, developmentbias (VBB) is applied as follows:

VBB = VR + (–220)

The adjusted development bias (VBB) is stored inmemory until the next process control initialsetting.



Image Density Control

Toner density sensor (TD sensor)

Developer consists of carrier particles (iron) and toner particles (resin and carbon). Inside thedevelopment unit, developer passes through a magnetic field created by coils inside the tonerdensity sensor. When the toner concentration changes, the voltage output by the sensor changesaccordingly.

Toner weight %



When new developer with the standard toner concentration (2.0% by weight, 20 g of toner in 1000 gof developer for the illustrated machine) is installed, developer initial setting must be performed byusing SP mode.

During this setting, the output voltage (VOUT) from the auto gain control circuit (AGC) on the maincontrol board PCB varies to change the output voltage from the toner density (TD) sensor. This isdone by changing the gain data as follows.

If the data is high, VOUT becomes high, and the sensor output voltage becomes high. As a result, thesensor characteristic becomes as illustrated by curve A. If the data is low, VOUT becomes low, andthe sensor output voltage becomes low. As a result, the sensor characteristic shifts as illustrated bycurve C.

By selecting the proper gain data, the sensor output is set within the targeted control level (VREF,VREF = 2.5 ±0.1 V). Now, the sensor characteristic is illustrated by curve B and the TD sensor initialsetting is completed. The selected gain data is stored in memory, and VOUT from the auto gaincontrol circuit stays constant during the toner sensor detection cycle.



Toner Supply Criteria

At every copy cycle, toner density in thedeveloper is detected once. The sensoroutput voltage (VTD) during the detectioncycle is compared with the toner supplylevel voltage (VREF).



Toner Supply Clutch on TimeTo stabilize toner concentration, toner supply amount (toner supply clutch on time) is controlled byreferring to VREF and VTD. The toner supply amount is calculated at every copy. The toner supplyamount is determined by using the following factors.

1. VREF – VTD

2. VREF – VTD' (VTD' = VTD of the previous copy cycle)

By referring to these factors, the machine recognizes the difference between the current tonerconcentration (VTD) and the target toner concentration (VREF). The machine also understands howmuch toner concentration has changed and predicts how much the toner supply amount will probablychange.

By changing the toner supply amount precisely, toner concentration (image density) is kept at aconstant level. Since the toner supply clutch on time updating is under fuzzy control, the relationamong VTD, V TD', VREF cannot be expressed by a simple algebraic formula.



VREF Correction

The image on the OPC drum changes due to variation of toner chargeability (influenced by theenvironment) even if the toner concentration is constant. The image density sensor (ID sensor)directly checks the image on the OPC drum and shifts VREF data (under fuzzy control) to keep theimage on the OPC drum constant, as explained in the next section.

NOTE: 1. Toner end condition is detected by the toner end sensor.

2. The toner supply clutch turns on at the intervals between each copy process whileimage development is not being performed.



Image density sensor (ID sensor)VSG and VSP are checked by the IDsensor [A]. The ID sensor is locatedunderneath the drum cleaning section.

There is no ID sensor pattern in theoptics, however, a pattern image is madeon the OPC drum by the charge coronaunit [B] and the erase lamp [C].

• VSG is the ID sensor output whenchecking the erased drum surface.

• VSP is the ID sensor output whenchecking the ID sensor pattern image.

To compensate for any variation in light intensityfrom the sensor LED, the reflectivity of both theerased drum surface and the pattern on the drumare checked.



In the above example, VSG is detected every time the machine starts copying. During VSG detection,the development sleeve rollers do not rotate and no development bias is applied.

VSP is detected after copying is completed if 10 or more copies have been made since VSP was lastdetected. Since the transfer belt must be released when checking VSP, a VSP check cannot be doneduring continuous copying.



Model A074—Process Control Using a V sensorThe copy process around the drum andthe copy image (image and backgrounddensity) are controlled by many factors.The following items are controlled duringthe copy process to maintain good copyquality:

• exposure lamp (optics)• grid bias (drum charge)• development bias (development)• toner supply (development)

The items above use various electricalcomponents for the various processcontrol functions. The most significant ofthese are for the control of the drumresidual voltage, exposure lamp voltageand drum aging.



Overview

During the OPC drum’s life, residual drum voltagegradually increases due to electrical fatigue. Thismay cause dirty background on copies. The Vsensor is used to avoid this problem. The Vsensor is located in the drum unit, near the IDsensor.

The CPU checks the drum residual voltagethrough the V sensor by directly sensing the VRpattern on the drum surface. This VR patterndetection is performed after the drum initialsetting. After this, the CPU will do one VR patterndetection every 200 copies for the next 2,000copies, and every 1,000 copies after that. Alsowhen VR data correction is applied and the drumtemperature goes over 25°C, this detection isperformed.

According to the data of VR pattern detection, theCPU applies VR correction to the grid bias voltageand the development bias voltage.

Residual Voltage



VR Pattern ControlThe VR pattern is made on the drumbefore the original latent image, as in thecase of the ID sensor pattern.

During VR pattern detection, the drumsurface is charged with a fixed grid biasvoltage: -500V + VG correction (DrumRotation Time Control). At the same timeall the blocks of the erase lamp unit turnon to illuminate this charged area of thedrum.

The exposed area of the drum is developed with a fixed bias voltage for non-image area: -160V + VRcorrection + VR Data correction (Drum Temperature Control) + Black Bias correction. The V sensorchecks the reflectivity of the bare area of the drum and this sensor output voltage is called Vrg. (Vrgis the same as Vsg detected by the ID sensor.) Next to this bare drum area, the drum is developedwith VR pattern bias voltage (0V). If there is residual voltage on the drum, this area of the drum willattract some toner, making a VR pattern. The V sensor checks the reflectivity of the VR pattern andthis sensor output voltage is called Vrp.



VR Correction

The CPU notes the ratio, of Vrp/Vrg. This VR pattern check is done 5 times in a row during the copycycle and the CPU takes their average. The reference voltage of the V sensor output Vrg, isautomatically adjusted to 4V at the same time as Vsg isadjusted.

VR Level VrpxVrg x 100(%) Grid bias correctionvoltage

Development biascorrection voltage

0 100~84 ±0 V ±0 V1 83~58 –40 V –40 V2 57~41 –80 V –80 V3 40~28 –120 V –120 V4 27~0 –160 V –160 V

The grid bias voltage and the development bias voltage are corrected (VR correction) according tothe ratio between Vrp and Vrg as shown in the above table.



VL Pattern Control Overview

Dirty optics or deterioration of the exposure lampdecreases the intensity of the light that reachesthe drum via the optics cavity. As more copies aremade during the drum’s life, the photoconductivelayer gets worn and drum sensitivity drops. Thedrum sensitivity also drops under low temperaturecondition.

VL pattern control is performed on this copier toprevent dirty backgrounds caused by the factorsmentioned above. The V sensor is used for VLand for VR pattern control.

The VL pattern (light gray) is located on thebottom of the left scale bracket. When a copy jobfinishes, VL pattern detection occurs. Theexposure lamp stays on for about 6 seconds whileat the home position. The VL pattern is lit and alatent image is made on the drum. After thisimage is developed, its reflectivity is checked bythe V sensor. The CPU notes the strength ofreflectivity, and if the reflected light is too weak,the exposure lamp voltage is increased.

ID Pattern



VL Pattern DetectionVL pattern detection is done after VR pattern detection, but unlike VR pattern detection it is done afterthe copy job is finished. This means after the drum initial setting, based on specific copy counts andwhen the drum temperature goes over 25°C under the VR data correction condition.

When VL pattern detection starts, the exposure lamp turnson, the main motor stays on, the charge corona, grid bias,all the blocks of the erase lamp, the pre-transfer andquenching lamps turn on. After about one drum revolution,the appropriate blocks of the erase lamp turn off and on tomake a VL pattern on the drum surface. The drum surfaceis developed with non-image area bias for both the baredrum and VL pattern.

The V sensor checks the reflectivity of the bare drum (Vlg)and the VL pattern (Vlp). The CPU calculates the ratiobetween Vlp and Vlg (Vlp/Vlg).

The VL pattern is made 4 times with 150 mm distancebetween each pattern. The CPU takes the average of Vlp/Vlg (=Vdat).



VL CorrectionWhen the drum initial setting (SP mode #66) is performedand more than 7 black copies are made, the initial VLdetection is performed at the end of the copy job and theCPU stores the VL reference value (initial Vlp/Vlg = Vref)in memory. ID sensor pattern detection and VR patterndetection is done prior to this initial VL detection.

ID sensor pattern and VR pattern detection are performed when black copies are made, even in theSP mode. VL pattern detection is performed only when a black copy is made in enlarge or full sizemode and not in the SP mode.

The V sensor output is automatically adjusted to 4V for both Vlg and Vrg) by SP mode. When the VLpattern detection is performed during the copy operation, the CPU compares the Vdat with the Vref.According to the ratio between Vdat and Vref, the CPU applies the voltage correction to the exposurelamp (VL Correction) as shown in the above table.

Vdat/Vref x 100 = VL level (%)

The exposure lamp voltage for VL pattern detection depends on all previous correction factors, andthe new VL correction factor is added to them. This result is then applied to the exposure lampvoltage till the next VL pattern detection.

VL Level (%)Lamp

correctionvoltage

151~> –1 V101~150 ±0 V

0~100 +1 V



Drum Temperature Control

Under low temperature conditions drum sensitivity drops and drum residual voltage increases. This isa characteristic of the drum and may cause dirty backgrounds on copies. To compensate for this, adrum thermistor is installed to monitor the temperature around the drum.

When the main switch is turned on, the CPU checks the temperature through the drum thermistor. Ifthe temperature is 25°C or less, the CPU applies appropriate corrections to the exposure lampvoltage (low temp. correction), to the grid bias voltage (VR data correction), and to the developmentbias voltage (VR data correction).

When the temperature goes over 25°C, the VR pattern detection and VL pattern detection areperformed and the corrections above are canceled.

If the temperature is already over 25°C when the main switch is turned on, no correction is applied.



Drum Rotation Control And VG Correction

OverviewDuring the OPC drum’s life the photoconductive layer gets worn and thiscauses a drop in drum sensitivity and adecrease in the drum potential after thedrum charge. The CPU keeps track ofthe drum rotation time that correspondsto the wear of the drum surface. Thegrid bias voltage is increased at setintervals (VG correction).

VG CorrectionIf drum potential decreases after thedrum charge, the ID sensor pattern onthe drum becomes lighter, causinghigher toner concentration in thedeveloper. Also, copy image densitybecomes slightly lighter. To controltoner density and copy image density,the drum potential is maintained byincrements of the grid bias voltage atset intervals. (See graph.)


PROCESS CONTROL OPC Digital Systems

OPC Digital Systems

Based on model A229

Overview

The drum potential will gradually change because of the following factors.

• Dirty optics or exposure glass• Dirty charge corona casing and grid plate• Changes in drum sensitivity

To maintain good copy quality, the machine does the following just after the main switch has beenturned on (if the fusing temperature is less than 100 °C and Auto Process Control [SP] is selected).

1) Potential Sensor Calibration2) VSG Adjustment3) VG (Grid Voltage) Adjustment4) LD Power Adjustment5) VREF Update

This process is known as ‘Process Control Initial Setting. The rest of this section will describe thesesteps in more detail.

Processes 1, 3, and 4 in the above list compensate for changes in drum potential. Processes 2 and5 are for toner density control.



Drum Potential Sensor Calibration

The drum potential sensor [A] detects the electric potential of the drum surface [B].

Since the output of the sensor is affected by environmental conditions, such as temperature andhumidity, the sensor needs recalibration at times. This is done during process control initial setting.

The development power pack [C] has two relay contacts. Usually RA102 grounds the drum.However, to calibrate the sensor, RA102 and RA101 switch over and apply the power pack outputvoltage to the drum shaft [D].



The machine automatically calibrates the drum potential sensor by measuring the output of thesensor when –200V and –700V are applied to the drum. From these two readings, the machine candetermine the actual drum potential from the potential sensor output that is measured duringoperation.

During calibration, if the rate of change in drum potential sensor response to applied voltage is out ofthe target range, SC370 is logged and auto process control turns off. The VG and LD poweradjustments are skipped; VG is set to the value stored in SP2-001-01, and LD power is set to thevalues stored in SP2-103.

VSG adjustment

This calibrates the ID sensor output for a bare drum to 4.0, ± 0.2V. It does this by changing theintensity of the light shining on the drum from the sensor. This is done automatically during processcontrol initial setting, and it can also be done manually with SP3-001-002.

If the ID sensor output cannot be adjusted to within the standard, SC350 is logged and toner densitycontrol is done using the TD sensor only.



VG Adjustment

The potential on unexposed areas of the drum(VD) gradually changes during drum life. To keepVD constant, the grid voltage (VG) is adjustedduring process control initial setting. The SBICUchecks VD using the drum potential sensor [A]. Ifit is not within the target range (-900V +– 10V),the SBICU adjusts VG (Grid Voltage) through theCharge/Grid power pack to get the correct targetvoltage. The most recently detected values canbe displayed with SP3-902-2 (VD) and 3-902-4(VG). If the CPU cannot get VD within the targetrange by changing VG, VG is set to the previousvalue and SC 370 is logged. For details of howthe machine determines an abnormal sensordetection see the A229 service manual (p7-9).



LD power adjustment

This adjustment uses the drum potential sensorto keep the ID sensor pattern at the samedensity, so that VREF will be updated correctly(see the next page). The VH pattern isdeveloped using the current LD power (thedensity is the same as the ID sensor pattern).The drum potential sensor detects the potentialon this pattern. The LD power is adjusted untilVH becomes –300V +–20V. This is done onlyduring process control initial setting.

The latest VH can be displayed using SP3-902-3. The corrected LD power can be displayed usingSP3-902-5 (the default is stored in SP2-103-1-4). See “Laser exposure” for more details about laserpower. If VH cannot be adjusted to within the standard within 25 attempts, LD power is set to thelatest value (the one used for the 25th attempt) and SC 370 is logged. For details of how themachine determines an abnormal sensor detection.



VREF Update

The TD sensor reference voltage (VREF) is updated to stabilize the concentration of toner in thedevelopment unit as follows;

New VREF = Current VREF + VREF

VREF is determined using the following Vsp/Vsg and VREF– VT table

VT: TD Sensor Output

When SC350 (ID Sensor Abnormal) is generated, VREF is not updated. The machine uses thecurrent value. VREF is updated during process control initial setting. It is also updated if both ofthe following conditions exist:

• 50 or more copies have been made since the last VREF update• The copy job is finished


PROCESS CONTROL Selenium Analog Systems

Selenium Analog Systems

Based on models A029 and A058

Image Density ControlChanging the strength of the positive bias voltage applied to the development roller sleeve controlsimage density. The bias voltage applied to the development roller sleeve reduces the potentialbetween the development roller and the drum. This reduces the amount of toner transferred to thedrum. So, the stronger the bias voltage is the lighter the resulting copy image will be.

The bias base level is set either by the operator through the manual image density keys (V1) or bythe automatic image density system (V2). The CPU increases the bias base level as necessary tocompensate for the rest time between copy runs and the drum temperature, both of which areaffected drum sensitivity.

Bias Compensation FactorsWhile not a true process control system, the drum temperature and rest time compensation of theseanalog systems was a forerunner of the systems we have today. The rest time (V3) and drumtemperature (V4) compensation factors affect only the development bias voltage value. Thesecompensation factors are added to the manual (V1) or automatic (V2) image density base biaslevels.



Rest Time Compensation (V3)The CPU increases the bias level as necessary to compensate for the rest time between copy runsand the drum temperature, both of which affect drum sensitivity.

<----------------------------------V3-------------------------------- >Copy #

Rest Time1 2 3,4 5,6 7-11 12

0 to 1 minute 30 30 0 0 0 0 1 to 6 minutes 60 30 0 0 0 0 6 to 30 minutes 90 60 30 0 0 0 0.5 to 3 hours 120 90 60 30 0 0 Over 3 hours 150 120 90 60 30 0

The drum sensitivity often drops slightly over the first few cycles of a copy run. This is because thelight from the exposure lamp fatigues the drum slightly. The amount that it drops depends on the resttime between copy runs—the longer the rest time the greater the change.

The A029/A058 copiers increase the bias at the beginning of each copy run to prevent variations inthe image density of the first few copies. The bias increase is shown in the above table.

When the main switch is turned on, the CPU will automatically select the greater than three hoursrest time compensation level.



Drum Temperature Compensation (V4)

When the switch on the bias powerpack is on, the development biaspower pack monitors the drumtemperature through a thermistor, andit increases or decreases the biasvoltage to compensate for temperatureinduced variations in drum sensitivity.The temperature compensation is -6volts for each degree increase in drumtemperature and is effective from 15°Cto 45°C.

However, if the bias switch is off, theCPU assumes a drum temperature of30°C. The power pack does notcompensate for temperature, and V4becomes +90 volts.


CCoolloorr PPrroocceesssseessThis chapter of the Core Technology Manual deals withcolor specific principles and processes. Discussions ofmonochromatic specific process or general subjectsthat are not affected by color will be found in otherchapters.

Principles of Color

When discussing the processes involved in colorcopying, it is important to understand what light isand how just three basic colors can create a vastarray of colors.

Electromagnetic Waves

Once thought to be the smallest particles ofmatter—atoms—have over time been shown toconsist of a variety of subatomic particles. Thesesubatomic particles are organized into threegroups—hadrons, leptons, and bosons.

0 1 111111

000

0

Principles of ColorColor ScanningColor DevelopmentColor Image TransferImage Files


Color Processes Principles of Color

The first group, the hadrons, includes amongothers the protons and neutrons that are found inthe nucleus of the atom.

Of the second group, the leptons, the electron isthe most important from the standpoint of color.Electrons are part of ordinary matter; the volumeof an atom is nearly all occupied by the cloud ofelectrons surrounding the nucleus.

The final group the bosons, includes the particlesresponsible for carrying the fundamental forces ofthe universe such as electromagnetic energy andgravity. One of them is a particle of major interesthere, the photon. You can think of the Bosongroup of particles as the universe’s tiny energytransporters. Photons then, are particles that forma packet of electromagnetic energy and cantransport this energy.

All matter and energy (as they are understood atpresent) consist of these particles. All matter thatwe normally deal with is made up of atoms. Forour purposes, we will consider an atom to consistof a positively charged nucleus surrounded by anegatively charged cloud of electrons. These

What do these particles have to dowith color?



negatively charged electrons encircle the nucleusin fixed orbits or shells. Each shell has its ownenergy level, and when energy is to be releasedfrom the atom, we will call upon the boson groupof particles to transport this energy outward.

If sufficient energy, say in the form of heat, isapplied to the atom, one or more of the orbitingelectrons will be forced to move to an outer shell.This process is referred to as absorption. An atomin which the electrons are boosted to higherenergy levels is said to be in an excited state.

As the electron returns to its “normal” energystate, electromagnetic radiation is released. Thisprocess is referred to as emission. One type ofelectromagnetic radiation is visible light. The colorof the visible light depends on the atom, how farthe electron moved to return to its initial orbit, andhow much energy was released.



Electromagnetic radiation consists of rapidlychanging electrical and magnetic fields, and isreleased from the atom in the form of particles or“packets” of energy. These tiny packets ofelectromagnetic energy are referred to asphotons. These particles of radiation released inmass numbers take on the characteristics of awave. The three wave characteristics ofamplitude, wavelength, and frequency aredescribed below. Photons are sometimes definedas particles of energy that behave like waves.

Along the radiation wave, the electric andmagnetic fields oscillate or go up and down instrength. The amount that the wave varies instrength is the amplitude.

Wavelength



The distance between one peak of the wave tothe next in either the electric or magnetic field iscalled wavelength, which is measured in meters.

And, the number of peaks that pass a given pointin one second is called the frequency. Frequencyis measured in Hertz (Hz).

1 second



Electromagnetic radiation covers a very broad spectrum of wavelengths. From the longest—theextremely long frequency radio waves (ELF)—through radio waves, television, microwaves, radar,infrared, visible light, ultraviolet, x-rays and on down to the shortest waves—the gamma rays.

The principle difference between the various kinds of radiation is their differences in wavelength,frequency and energy. As the wavelength decreases, both the frequency and energy increases.

Notice that visible light occupies only a narrow band of the spectrum between about 400 and 700nanometers.

GA

MM

A R

AY

S

X R

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INF

RA

RE

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FM

BR

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DC

AS

T /

TV

EL

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SH

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T W

AV

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AM

BR

OA

DC

AS

T

MIC

RO

WA

VE

S

ULT

RA

VIO

LE

T

VIS

IBL

E L

IGH

T

V B G O R

WAVELENGTH,METERS

400 500 600 700 (nm)

InfraredUltraviolet

10- 1 6

10- 1 4

10- 1 2

10- 1 0

10- 8

10- 6

10- 4

10- 2

1 102

104

106

108



• Some wavelengths are long and less frequent.

• Other wavelengths are short and morefrequent.

• The longer the wavelength the lower thephoton’s energy.

• The shorter the wavelength the greater thephoton’s energy.

• A red photon of light (longer wavelength) hasabout half the energy as that of a blue photonof light (shorter wavelength).



The Visual Spectrum

Visible light occupies a very small portion of thiscontinuous spectrum. The electromagnetic energywith wavelengths of between about 400 nm and700 nm makes up the entire visible light spectrum.(The abbreviation “nm” refers to a unit of measurecalled a nanometer. One nanometer is equal to0.000000001 meters or written in exponential form1x10-9 meters.) This range of wavelengthsconsists of all the colors of light that humans areable to perceive. White light contains all thesewavelengths and hence, contains all the colors ofthe visible spectrum.

This can be demonstrated through the use of aprism. A prism works on the principle of refraction,or the bending of light. As light passes throughdense matter (such as glass), longer wavelengthsof color bend less than shorter ones. In thismanner the various wavelengths of color benddifferently from one another. The result is that allthe individual colors that make up white light areseparated from one another, producing a“rainbow” of colors.



As you can see in the previous illustration, thedivisions between the colors are not pronouncedor sharp. If you begin at the top, you may noticethe color red, then going down through thespectrum you may be able to pick out a reddish-orange, then maybe an orange, a yellowish-orange and so on down through to the color violet.

We perceive certain colors based on theproportion of one color to another. For example, ifthe ratio of yellow light to orange is 1:1, we wouldperceive the color as yellowish-orange. If the ratiowas increased to 2:1, we would perceive the coloras yellow-yellowish-orange, and so on. There are,however, three primary colors of light that whenany two are mixed together, in equal amounts, anew or secondary color is produced. And, when allthree of these colors of light are blended togetherin equal amounts “white light” is produced. Thethree primary colors of light that best produce thiseffect are the colors red, green, and blue.

Since all the various colors of light, as well as white light, can be created by combining these threecolors in varying amounts, it is then possible to categorize visible light (from about 400nm to about700nm) into three basic categories

Range of Wavelengths Color

400nm to about 500nm Blue

500nm to about 600nm Green

600nm to about 700nm Red



Reflection and Absorption

Luminous Color and Intrinsic ColorWe see objects that create, reflect, or transmit,visible light. Objects that create light are said to beluminous. Luminous color is the color emitted byan object, and is dependent upon the wavelengthsproduced. Objects that reflect or transmit light aresaid to be intrinsic. Intrinsic color is the result ofthe wavelengths of light that are bounced off anobject (reflected), or that are allowed to passthrough a translucent or transparent object(transmitted color).

For example, the sun, a candle, a television or ared spotlight are all examples of luminous color.They all generate light.



Reflection and AbsorptionAn orange, the pages in a book, a leaf or atransparent piece of blue glass have intrinsiccolor. The colors they produce are the result ofabsorbing or stopping some wavelengths of light,while reflecting or passing others.

As white light strikes the leaf, the greenwavelengths are reflected, while the otherwavelengths are absorbed.

When white light strikes the blue glass, the bluewavelengths pass through and all otherwavelengths are stopped (absorbed). The eyeperceives the color blue.

Substances which are colorless, such as air, areunable to absorb any of the wavelengths of light.Colorless substances either reflect all thewavelengths of light striking it, such as whiteclouds, or allow all the wavelengths to passthrough, such as the glass in a window.



All the visible colors of light can then beexpressed as some combination of three principlecolors of light— red, green, and blue. It is thisability to reproduce all the colors of light using onlythree basic colors that is called additive colormixing. Red, green, and blue light are referred toas the three additive primaries.

Light Reflective Characteristics of Color Toner.The light reflective characteristics of color tonerare of special interest to us. We will get into this inmore detail later, but for now lets take a quick lookat how color toner reflects light.

Cyan toner absorbs red rays and reflects blue andgreen rays. Reflected “B” and “G” rays are seenas cyan.

R

BG

Cyan Toner

White paper



Magenta toner absorbs green rays and reflectsblue and red rays. Reflected “B” and “R” rays areseen as magenta.

Yellow toner absorbs blue rays and reflects greenand red rays. Reflected “G” and “R” light rays areseen as yellow.

Magenta Toner

White paper

R

BG

R

BG

Yellow Toner

White paper



Color Mixing

The Primary Colors Colors can be created by mixing three primary colors in two basic methods. One is additive color mixing, which is the mixing of the three primary colors of light. The other is subtractive color mixing, which is the blending of the three primary colors of pigment (such as ink, paint, or toner).

Subtractive color mixing uses cyan, magenta, and yellow.

Additive color mixing uses red, green and blue.

7 October 2003 Page 1031


Additive Color MixingIn additive color mixing red, green, and blue lightare blended in various amounts to produce allother colors and white light. Additive Color Mixingis the process used by color televisions, and bycolor computer monitors.

As discussed earlier, if equal amounts of red light,green light, and blue light are mixed together,white light is produced. The resultant color createdwhen mixing colors of light using the additivetheory of color is “brighter” and lighter in color theneither of its elements. The colors “ADD” together.

When only two of the three primary colors aremixed together, in equal amounts, the colorcreated is referred to as a secondary color.

When equal amounts of red light and green lightare mixed together, the color yellow is produced.

Red + Green ! Yellow



Mixing equal amounts of red light and blue light,produce the color magenta.

And when equal amounts of green light and bluelight are mixed together, the color cyan isproduced.

Red + Blue ! Magenta

Green + Blue ! Cyan



When one of the additive primary colors iscombined with one of the secondary colors andthe result is white or near-white light, the twocolors are said to be complementary. Forexample, cyan light consists of green and bluelight, adding cyan to red light would create whitelight. So, the color cyan and the color red areconsidered to be complementary colors.

By the same reasoning, the color magenta isformed by the mixing of equal amounts of bluelight and red light. If these colors were added inthe correct proportions to green light, white lightwould be the result. Magenta and green arecomplements.

The table lists the additive primaries and theircomplementary colors.

When mixing pigments, such as ink or dye, thesecomplementary colors are used as the principle orprimary colors in a process known as subtractivecolor mixing.

AdditivePrimary Color

ComplementaryColor

Blue Yellow

Green Magenta

Red Cyan



Subtractive Color MixingMixing colors of light is one thing, but mixing opaque colors such as pigments or dyes is quiteanother. For example, red and green pigments will not blend to produce the color yellow no matterhow hard you try. This is because these materials get their color by absorbing or “subtracting” certainamounts of red, green, and blue light, and reflecting what is not absorbed.

This means that a pure red pigment would absorb blue and green light and reflect only red light; apure green pigment would absorb red and blue light and reflect only green light; and a pure bluepigment would absorb red and green light and reflect only blue light. The mixing of any two of thesethree pigments, red, green or blue would result in all three primary colors of light being absorbed,which is black. So as you can see, in a three color print process, using the colors Red, Green, Blue,as pigments would not work. What must be determined are the three principle or primary subtractivecolors.

As you read the above paragraph you may have noticed that for each color pigment: pure red, puregreen, and pure blue; two colors of light were absorbed or subtracted by each. If we had threedifferent colors, colors that would each absorb only one color of light, then by mixing these threecolors we could control the absorption of any combination of the three colors of light, resulting in theability to create any color.

As we mentioned earlier three separate colors do exist that will each absorb only one of the threecolors of white light, namely the complementary colors of red, green and blue which are cyan,magenta, and yellow. These three colors are referred to as the subtractive primaries.



Cyan, Magenta and Yellow will each absorb adifferent additive primary and reflect the remainingtwo.

When white light strikes a pure yellow pigment theadditive primary blue is absorbed and theremaining two additive primaries, red and green,are reflected. Remember, red and green lightcreate yellow light. When white light strikes a puremagenta pigment, green is absorbed and red andblue are reflected. Red and blue light createmagenta light. And as shown here, when a purecyan pigment is used, red is absorbed and greenand blue are reflected. (Green and blue = cyan)



When magenta pigment (the circle on the left) ismixed with yellow pigment (the circle on the right)in equal proportions the color red is produced(center).

When yellow pigment and cyan pigment are mixedtogether in equal proportions, the color green isproduced.

Yellow + Cyan ! Green

Magenta + Yellow ! Red



When cyan pigment is mixed with magentapigment in equal proportions, the color producedis blue.

When all three colors: cyan, magenta and yelloware blended together in equal pro-portions, theresult is that all the wavelengths of light areabsorbed, and black is produced. This black coloris referred to as “processed black,” and dependingon the purity of the colors for cyan, magenta, andyellow will actually appear to be a very deep blueor brown.

Cyan + Magenta ! Blue



The final color created, when mixing pigmentsusing the subtractive theory of color, is always“darker” and deeper in color than either of itselements. The colors, when mixed together,“Subtract” light from being reflected.

The colors, cyan, magenta and yellow, known asthe subtractive primaries, will be the colors usedto print the images when using the three colorprint process.

The illustration to the right is an example of asimple “color wheel.” Starting at the color greenand following the top arrow, moving clockwisetoward red is the color yellow. Remember, yellowis produced by mixing equal amounts of greenand red light. Continuing clockwise past red is thecolor magenta, which is a mixture of red and bluelight. Then comes cyan and so on... Notice thateach portion of the color wheel points to itscomplementary color. For example the red“wedge” points to its complement cyan. The bluewedge to its complement yellow.

Not only does this color wheel show therelationships of the additive primaries, it also



demonstrates the relationships of the subtractiveprimaries. For example, yellow and cyan pigmentsmixed in equal amounts create green. The color“green” sits between yellow and cyan on the colorwheel. Green also points to its complement whichis magenta. There are other, more elaborate colorwheels, that can also demonstrate all the various“hues” of colors created as the proportions of thevarious colors mixed are changed.

Familiarizing yourself with the color wheel can bea strong aid to obtaining a specific color. Forexample, using the color wheel, when equalproportions of magenta and yellow pigments aremixed, red is produced. If the amount of magentawas reduced the color would take on a moreorange look to it. Reduce the magenta even moreand the color would begin to appear more andmore yellow. Understanding these concepts ofhow cyan, magenta and yellow interact in formingall the printed colors are important in bothoperating and servicing any device using the threecolor print process, such as a full color copier.

Some Color Wheels

An additive mixingcolor wheel

A subtractive mixingcolor wheel

A continuous colorwheel



Color Separation

“Color Separation” can be thought of as theopposite of “Color Mixing.” The process of colorseparation will take a full color image and “break itdown” to its fundamental or primary components.This is accomplished using the intrinsic colortransmission properties of optical filters. Althoughthe process of color separation can beaccomplished by using either the additive filters—Red, Green, or Blue (R,G,B), or subtractivefilters—Cyan, Magenta, or Yellow, when used inthe three color print process, such as used in colorcopiers, generally R,G,B filters are used. For thisreason we will limit our explanation to the use ofthese three filters.

The Characteristics of Filters

Red Filter—The “Red” filter allows “Red” light topass through and absorbs “Blue” and “Green”.

G RB

Red Filter



Green Filter—The “Green” filter allows “Green”light to pass through and absorbs “Blue” and“Red”.

Blue Filter—The “Blue” filter allows “Blue” light topass through and absorbs “Green” and “Red”rays.

Let’s look at the separation process...

White light is first cast upon a full color image orobject. Depending on the color of the image orobject, certain wavelengths of light will beabsorbed while others are reflected. The colorswhich are reflected can be considered as beingcomposed of various proportions of the threeprimary colors: red, green, and blue.

G RB

Green Filter

G RB

Blue Filter



By passing the reflected light through a red filter,only the reflected light that consists of a redcomponent will pass through. The intensity oramount of red that passes through is in directproportion to the amount of red light reflected bythe image. In other words, a pure yellow pigmentwould reflect red and green light in equalamounts. A red filter passes only the red element,hence the intensity of the light passed is only halfof when the red and green light were combined.

White light is cast on the image again. This timethe reflected light is passed through a green filter.The filter transmits only the green element of eachcolor; the other colors are blocked.



Again, white light is cast on the image. This time ablue filter intercepts the reflected light. Only theblue element of each color from the image isallowed to pass.

These steps are basically what occur during thecolor separation process in a full color copier.Each time white light is cast on the image wouldbe equivalent to one scan of the copier. For eachscan, the reflected image is passed through adifferent color filter. The end result is that theimage is “broken apart" into its R,G,B,components.

Image ScanningThe three-scan process has been replaced by afour-scan process in almost all modern full colorcopiers. The fourth scan is used to determine howmuch black pigment or toner should be added tothe reproduced image. This is because thepigment or toner colors used are not necessarilypure. The magenta used may not be a puremagenta color, the cyan, not a pure cyan, and theyellow, not a pure yellow. This is due primarily tomanufacturing, since the materials used to create



the pigment color must also meet a range ofrequirements that are independent of color, suchas: resistance to caking or clumping, consistencyof particle size, or in the case of liquids the flowrate. The materials chosen to meet all thespecifications may not wind up being pure in hue.For this reason black toner is used to produce amore true black, instead of the bluish or brownishlook of a processed black. The amount of blackused is usually a percentage of the C,M,Y ratioused—a process referred to as under colorremoval.

After scanning, the next process involves usingthe RGB separated color data and determininghow much toner to apply. This is referred to asRGB to CMYK conversion (K = BLACK toner).This step is generally performed immediately aftereach scan before the next scan occurs. Since thesubtractive primaries (C,M,Y) are the opposite orcomplements to the additive primaries (R,G,B),the amount of toner used is inversely proportional(or the opposite of) the amount of light transmittedthrough each filter.

Original image

CMYKseparationsafter RGB toCMYKconversion



Let’s examine the light transmission and tonerselection for a solid pink original.

Since a large amount of red light is reflected fromthe pink image, then very little red light wasabsorbed. The color that absorbs red light is itscomplementary color cyan. Cyan pigment absorbsred light. Since very little red was absorbed by theimage, the image must contain very little cyanpigment. So a very small amount of cyan toner willbe used.

The pink original reflects only a very small amountof green light; so, a large amount must have beenabsorbed. The color pigment that absorbs greenwavelengths of light is the complementary color ofgreen, which is the color magenta. So, a largeamount of magenta toner will be necessary toreproduce the color of this image.



Finally, the pink original reflects a moderateamount of blue light; so, a moderate amount mustalso have been absorbed. The color pigment thatabsorbs blue light is the complementary coloryellow. And a moderate amount of yellow tonermust be added to reproduce this image.

Blended together using heat and pressure, theend result is a copy or reproduction of the originalimage in full color. In this example the color “Pink”is reproduced.



By altering the proportions of cyan, magenta andyellow pigments used, based on the levels of red,green and blue light reflected, any color can bereproduced. Adding a fourth pigment, black, at theproper amount adds depth to the copy andimproves black reproduction. And those are thebasic processes surrounding light and colormixing.



Brightness, Saturation, and Hue

We will finish the section on the principles of colorwith a discussion of three important terms—brightness, saturation, and hue.

These color characteristics form one of thesystematic models available for classifying colors.It is based on how the eye perceives shades ofcolor.

Brightness: This is related to the amount of blackor white in a color. It is also a measure of howmuch light the color is reflecting. Adjusting thelightness changes the intensity of R, G, and B butkeeps their proportions the same. Brightness isalso known as ‘lightness’.

Saturation: Colorfulness with respect to a neutralgray (chroma is another term used). To adjustsaturation, the intensity of the complementaryRGB color is adjusted, keeping the dominant colorthe same.

Hue: This is the color of an object. It is a measureof the proportions of R, G, and B in the color.

Black

White

RedBlue-green

Green-blueBlue Violet

Orange

YellowGreen-yellow

Green

Bri

gh

tnes

sB

rig

htn

ess

Saturation

Hue



These three characteristics of color can be shownon a three-dimensional diagram as shown on theprevious page. The illustration on this page is acolor representation of this concept.

In this diagram, the brightness increases towardthe top apex and decreases toward the bottomapex. All colors can be represented as a verticalcolor section in the solid, with a white apex at thetop and a black apex at the bottom.

The colors going through the center of the solidfrom top to bottom are all shades of gray. Also,colors get brighter (more white) above theequatorial plane, and darker (more black) below it.

The colors get more intense as you move awayfrom the vertical axis (the percentage of graydecreases). This represents increase insaturation.

Any horizontal slice through the solid yields ourfriend the color wheel. The hue changes as youmove around the center.

A 3D “brightness, hue,and saturation” colordiagram



Color Matching

In theory, color management is simple; the colors eithermatch the original, or they don’t. In practice, however, it ismuch more complex. While accurate color matching is a goalof almost every color process, it is not always possible. Thereare a number of technical elements that limit our ability toreproduce specific colors, as well as psychological elementsthat influence our perception of colors. Understanding thesewill help you create a close-as-possible color match.

Color GamutA color gamut is the maximum color range for a particulardevice. Different devices and different color processes havedifferent gamuts.

The illustration on the right represents the entire visualspectrum—the color gamut visible to the human eye. The area inside the yellow triangle represents atypical RGB gamut. This is the color range that can be displayed on a typical monitor.

While the actual gamut will vary from monitor to monitor, it is always smaller than the visible range.There are always some colors that cannot be displayed.

The area inside the blue line represents a typical CMYK device. This, too, will vary depending on thequality of the printer or copier, but it is smaller than the RGB gamut. The unfortunate result is, some



colors can be displayed on a monitor but cannot be printed. You can calibrate, adjust and manipulatethe printer as much as you like—you won’t get the desired color.

Dark blue shades are a common example. On some printers certain blues come out purple.

MetamerismMetamerism is an illusion in which two or more colorsappear identical under certain light sources, but aremarkedly different from each other under other lights.This is a common problem in the paint, printing andtextile industries.

A typical example of metamerism occurs when you try topaint yourliving room tomatch yourcouch. Youtake a fabricsample withyou to thehardware store, but while the paint chip and fabric samplematch perfectly under the store’s florescent lighting, theylook quite different in your living room’s blend ofincandescent and natural light.



Metamerism is a particular problem for CMYK processes, where the colors are created from justthree colorants.

Part of the problem is that, as we discussed earlier, light has color. Different light sources producedifferent colors—and these colors influence the appearance of fabric samples, paint chips and colorcopies.

The color of a light source is described by its temperature. The temperature scale is calculatedbased on the amount of light emitted by a blackbody at any given temperature.

Blackbodies are theoretical objects that are perfectly black when cold. At zero degrees Kelvin theyabsorb all light cast upon them; however, as they heat up, they begin to emit light—first red, thenyellow, then white and finally blue.

While perfect blackbodies do not exist, most solid objects are a good approximation of blackbodies.Think of the coils on an electric heater, the filament of an incandescent bulb, and even the sun andstars.

Color temperatures are measured using the Kelvin scale. Kelvin is similar to Celsius. The unitintervals are the same; however, zero K is equal to -273 degrees Celsius.

Note, hotter temperatures emit bluish light. Cooler temperatures emit reds. This runs contrary tomost people’s color intuition. Blue is usually seen as a cold color. Red as warm or fiery.



Color Temperatures12000 K11000 K

Clear blue sky at noon

10000 K9000 K

Graphics arts monitor

8000 K North Sky Light7000 K Overcast Sky at noon6000 K Sunlight at noon5000 K Standard Color viewing lamps,

Cool white florescent4000 K Photoflood tungsten,

Warm white florescent2854 K Tungsten incandescent lamp2000 K Sunlight at sunset, Candlelight

When matching colors it is important to consider the light that the objects will be viewed under. Mostprofessional color matching goes one step further—using strict lighting standards when comparingproofs. 5000 K is the default standard. This produces a completely neutral, white light source, similarto natural daylight. To be even more precise, the ANSI standard also defines the chromaticity,spectral power distribution, color rendering index, and intensity of the light for viewing differentmedium.

Color temperature of standard light sources


Color Processes Color Scanning

Color MemoryWe are often disappointed with color reproduction, when thecolor does not live up to our memory of the scene. The truth is,colors that we remember are not always the colors we actuallysaw.

People tend to remember colors as being more vibrant, morerich than they actually where. If you take two prints of the sameobject, one with accurate coloring and one with over-saturatedcoloring, most people will pick the over-saturated one. Itappears more alive and more interesting.

This is just one way in which psychology influences ourdefinition of a “quality color image.”

For hands on experiments with interestingonline applets, check out

http://www.cs.rit.edu/~ncs/color

Over saturated colors

Normal colors


http://www.cs.rit.edu/~ncs/color


Color Scanning

In this section we will look at the aspects of imagescanning and photoconductor exposure that areunique to color systems. The details of processesthat are common to both color and black/whitesystems are covered in Photocopying Processesand Digital Processes chapters.

Ricoh color products have used three differentscanning methods, depending on the underlyingbasic architecture of the machines. Thesemethods can be classified as color analogscanning/exposure, digital systems using lens andmirror scanning, and direct scanning digitalsystems using a fiber optic array. We will discussand look at examples of each.

The number of scans that a color copier makesdepends on the amount of memory it has. Mostcolor copiers must make one scan per color.However, digital color copiers with a large amountof memory—for example model A269—can storethe full image data for all colors and need onlyone scan per image.

Digital with lens and mirrors

Analog

Digital with fiber optic array



Analog Scanning

Most color machines are digital. However, thereare some analog color machines in the field.

The color analog scanning and exposure isbasically the same as the systems used for blackand white analog copiers. (See and Exposure inthe Photocopying Processes chapter.) The onlydifference is that filters have to be used toseparate the colors and the original has to bescanned for each of the primary colors to bereproduced.


The illustration to the right shows the scanningmechanism of models A030/A072.

During the copy cycle, an image of the original isreflected onto the drum surface via the opticsassembly.

Three color filters (red, green, and blue) and aneutral filter are mounted on a rotor. The threecolor filters are used when the full color mode isselected or single color erase mode is selected.

Exposure Light Path:Exposure Lamp [A] ⇒ 1st Mirror [B] ⇒ 2nd Mirror [C]⇒ 3rd Mirror [D] ⇒ Lens [E] ⇒ 4th Mirror [F] ⇒ Color Filter[G] ⇒ Toner Shield Glass [H] ⇒ Drum [I]

Optics cooling fan: [J]



The neutral filter is used when black copies orsingle color copies are made.

The filter rotor, which holds the four filters [A], isshown to the right. The rotor turns to bring theproper filter into the light path. A home positionsensor [B] informs the CPU when the rotor is atthe home position. A stepper motor [C] rotates thefilter rotor the precise angle to bring the selectedfilter into the light path.

[B]

[A]

[C]



Lens and Mirror Digital Scanning

Most color digital machines use a lens andscanners with mirrors to reflect an image of theoriginal to a charge coupled device (CCD). This isvery similar to the system used in most digitalblack and white copiers.


An image of the original illuminated by theexposure lamp [A] (a halogen lamp) is reflectedonto a color CCD [B] (Charge Coupled Device) viathe 1st [C], 2nd [D], and 3rd [E] mirrors, filter, andlens [F]. The filter removes infrared from the lightreflected off the original; this is particularlyimportant for glossy photos with black areas,which can appear reddish in copies.

For all copy modes except the “Auto OriginalType” mode machine makes a single scan. TheCCD is a one-chip color CCD with RGB colorfilters. The scanning resolution is 400 dpi (5,000pixels).

[B]

[C]

[D]

[E]

[F]

[A]



The key element in digital color machines is thecolor CCD. The color CCD resembles the type ofCCD used in black & white digital machines;however, it has three rows of light sensitiveelements instead of one row. The color CCDconverts light reflected from the original into threeanalog signals, one for each of the three basiccolors Red, Green, and Blue. The signals arecalled the R, G, and B signals. A single scangenerates a separate set of three signals (RGB).

The CCD consists of three lines of 5000 elementsat a resolution of 400 dpi (15.7 dots/mm)—oneline for each color. To make the R, G, and Bsignals, each line has a color separation filter (R,G, or B). The lines of CCD elements are veryclose together, but there is some space betweenthem. In model A269 the lines are spaced 4 pixelsapart at full size magnification—illustrated to theright. (In many earlier models they are spaced 8pixels apart.) To correct for the spacing, the R, G,and B signals must be synchronized. This is doneby delaying the signals in memory buffers on theimage processing unit (IPU) board. This processis called scan line correction.

1

5

9

2 31R

G

B

5000



The CCD is mounted on the board with the lensblock (the assembly is known as the SBU orSensor Board Unit). Therefore, to replace theCCD, you must replace the SBU.



Direct Digital Scanning (SELFOC +CCD)

Color direct digital scanning systems use a self-focusing fiber optic array (SELFOC) and full-sizeCCD mounted together on a scanner. The basicprinciple of this method is quite simple. As thescanner moves across (scans) the original, a stripof the original is reflected through the fiber opticarray to the CCD.


The scanner unit used in models A046 and A105consists of two exposure lamps [A] (fluorescentlamps), the full-size CCD [B], the CCD drive board[C], the CCD pre-amp board [D] and the opticalfiber array [E]. The light from the exposure lampsexposes the original and reflects on to the full-sizeCCD through the optical fiber array.

[B][C]

[D]

[E]

[A]



The full-size CCD board has an unusual design.There are 5 CCD chips on the CCD board, eachCCD chip has 2,928 elements (2,880 elements formodel A105). Each element has a tiny green (G),blue (B), or red (R) filter on top. This G.B.R. orderis repeated along the full length of the CCD chips.One set of these G.B.R. elements is equal to onepicture element or pixel. The CCD elements areangled 45 degrees, so that all three CCDelements of any pixel receive the same reflectedlight.

62.5 µm

45°

1 pixel


Color Processes Color Development

Color Development

Like black and white machines, color copiers andprinters use dual-component development ormonocomponent development systems. However,color systems require a separate developmentunit for each color, and they must make at leastone development cycle per color.

The development systems of Ricoh color productscan be classified into three groups—(1) systemswith the development units arranged in fixedpositions around the photoconductor, (2) systemswith a revolver that brings the development unitsto the photoconductor when needed, and (3)tetradrive systems. This section looks atrepresentative examples of each group.

KC

Y

M

1std

2nd

Development unitson a revolver

Tetradrive

Developmentunits in fixedpositions



Fixed Position Development Systems

Many color copiers and printers have the four color development mechanisms (CMYK) arranged infixed positions around the photoconductor. Such an arrangement is logical from a design point ofview; however, such designs have two requirements that designers must address.

1. Photoconductor Surface AreaFour development mechanisms take up a lot of photoconductor surface. For this reason, colorsystems using fixed position development units must use a larger than normal photoconductor. Oneway is to increase the drum size; this is the approach used by model A109 as explained in example 1below. Another method is to use a long photoconductor belt; this is the method used by model G033(see example 2 below).

2. Prevention of Simultaneous DevelopmentAlthough the development units are in a fixed position, only one color can be allowed to develop theimage at a time. Examples 1 and 2 below show two ways to handle this requirement—model A109removes the developer from the rollers that aren’t being used for development, and model G033holds the development rollers away from the photoconductor when they are not in use.




This machine has one large development unitdivided into four sections. From the left they arethe black development section [A], the cyan deve-lopment section [B], the magenta developmentsection [C] and the yellow development section[D]. Each development section has a sleeve roller[E], dual mixing roller [F], doctor plate [G], andtoner density sensor [H].

To make room for the four development sections,model A109 uses a drum with a diameter of 120mm. (Other Ricoh color systems typically use a 90mm diameter drum.)

Continued on next page.

[B]

[C]

[D]

[E]

[F]

[G]

[H]

[A]



One interesting feature of this machine is the useof six motors to drive the various developmentcomponents. The color development drive motordrives the dual mixing rollers in the cyan,magenta, and yellow development sections. Theblack development drive motor drives those in theblack development unit.

Each of the four sleeve rollers is driven by anindependent, reversible motor [A]. When thesleeve turns as shown by the black arrows,developer is carried to the OPC drum. When thesleeve turns in the direction of the white arrows,all the developer left on the sleeve roller surface isreturned to the development section. Only onecolor development section at a time carriesdeveloper to the drum.

[A]



Example 2: Model G033

This machine has the four color developmentunits [K,Y,M,C] arranged along one side of anOPC belt [A].

When the printer is idle, none of the developmentunits contacts the OPC belt. During printing, themachine moves the development units intocontact with the belt one at a time. (Refer to theG033 service manual for details. The mechanismused is a standard mechanical system using asolenoid, a spring clutch, and a cam.)

[A]



Revolver Systems

Revolver Operation OverviewMachines using the revolver system have the fourdevelopment units (K, Y, C, and M) mountedaround a rotating mechanism called the revolver.The revolver rotates to bring the proper colordevelopment unit to the drum. Revolver systemsuse a standard size OPC drum.

Example: Model A257/A269

The illustrations to the right show the revolver [A]used in models A257 and A269.

The revolver unit holds four development units,one for each color (KYCM). It develops colors byrotating the revolver counter-clockwise (as viewedfrom the front of the copier), 90 degrees at a time,in the order K, Y, C, and M. (In printer mode, thismachine develops in the order Y, C, M, and K toimprove the reproduction of black letters.)

KC

Y

M

1std

2nd

[A]



Tetradrive Systems

The tetradrive system uses four print engines lined up in a row. It hasfour drums, four laser beams, four charge corona units, four transfercorona units, and four development units. The four print engines allowthe creation of the CMYK images simultaneously, thus greatlyincreasing the full color copy speed. The primary drawback of thetetradrive system is expense.

Examples of the original tetradrive system include models A092 andA105. The development units of these products use a standarddual component development system. The components of thedevelopment units of model A105 are illustrated to the right.

[A] OPC drum[B] Development roller[C] Toner supply roller[D] Transport rollers[E] Mixing augers

[B]

[C]

[D]

[E]

[A]



Newer tetradrive systems (sometimes called four-tandemsystems) have a number of improvements over the original.

In the model G060, the paper path is inclined about 38degrees to make the machine as compact as possible. Thedevelopment units are redesigned, and there are four motors.

Development drive motor-K drives the development unit forblack, the fusing unit, and the paper exit section.

Development drive motor-CMY drives the developmentunits for magenta, cyan, and yellow, the registration roller andby-pass feed mechanism.

Drum drive motor-K drives the PCU for black and the transferunit.

Drum drive motor-CMY drives the PCUs for magenta, cyan,and yellow.



Toner Supply Control

Current machines generally use fuzzy logic to control toner supply. Most use two inputs to the fuzzycontrol algorithm—the amount of toner attracted to the drum as sensed by the ID sensor and thecalculated volume of toner used based on pixel count. (See example 1.) Higher end systems alsouse a toner density sensor. (See example 2.)

Note: While the explanation and examples in this section are given using machines with revolverdevelopment units, the basic information applies to other machines—both color and black and white.


Fuzzy Control ModeFirst, the machine assesses the amount of tonerper unit area on the drum (M/A). This isdetermined from two sensor inputs: Vsg, andVsp(toner).

The fuzzy logic algorithm then uses the mostrecent M/A values to assess current toner densityconditions.

The output from the fuzzy logic process is thencombined with the image area ratio obtained fromthe image data signal coming from the IPU board.The result of this calculation is the amount of

Vsp Detect ion for TonerSupply Control

Image Area Rat io

Required Amount of Toneris Determined

Copy

Toner Supply MotorDurat ion is Calculated

Fuzzy Control



toner required, and from this, the machinedetermines the time that the toner supply motormust stay on in order to supply the correct amountof toner.

Vsp detection for toner supply controlThe copier generates an ID sensor pattern using astandard laser diode power. The copier generatesthis pattern between the K, C, M, and Y images,and then detects the density using the ID sensor.The result is known as ‘VSP for toner supplycontrol’, or ‘VSP (toner)’ to distinguish it from theother VSP, measured during potential control.

This process is done after

• Each color development cycle for odd-numbered copies when making continuouscopies of A4/LT landscape size or smaller.

• Each color development cycle, every copy in allother modes.

Calculating the amount of toner on the drumFirst, the machine calculates a value from thecurrent VSP (toner) value. Then, it refers to a table

2 0 m m

2 0 m m



in the ROM to determine the toner density on thedrum (M/A).

• M/A: Toner amount per unit area on the drum(mg/cm2)

The target M/A for toner supply control is 0.4mg/cm2 for the C, M, and Y toners and 0.3mg/cm2 for the K toner. M/A is calculated in thesame way as for potential control.

– Fuzzy Logic Algorithm –

The fuzzy logic algorithm has two input factorswhich are related to the amount of toner on thedrum. These are:

• The difference between the average of theprevious 10 M/As and the target M/A

• The tendency of the previous 10 M/As

– Image Area Ratio –

This is a measure of how much toner will beneeded for each color on a page. From the image



data from the image processing unit (IPU), themachine determines the total amount of the coloron the page. It takes into account the grayscalevalues for each pixel for that color.

Fixed Supply ModeModels A258/A259/A260 normally use the fuzzylogic supply mode described above. The fixedsupply method is used only when abnormalconditions occur during the process control selfcheck. In fixed supply mode, the machine adds afixed amount of toner to the developer every copy.Readings from the ID sensor are ignored.

The toner supply ratios for each color in fixedsupply mode are determined by service programs(SP 2-208-005 to 008).



Example 2: Models A257/A269

Fuzzy Control ModeThe toner supply control of models A257 and A269 is similar to that described in example 1 above.However, in the fuzzy logic control mode, input from the toner density sensor (TD sensor) is alsoused in the calculation. Thus these machines use three input parameters as follows:

1. Density of the toner read by the TD sensor

2. Amount of toner attached to the drum sensed by the ID sensor

3. Pixel count (image area ratio)

The amount of toner supplied is determined by the toner supply clutch on time

Other Toner Supply Control ModesIn addition to the default fuzzy logic control mode, these copiers have a proportional control modeand a fixed supply mode.

The proportional control mode is used if an ID sensor becomes faulty. Only the TD sensor is used tocontrol toner supply.

The fixed supply mode is used if both the TD sensor and ID sensor become faulty.



TD Sensor OutputThe relationship between the TD sensor output Vtand the toner density in the developer is shown inthe figure on the right. The target toner density ofthis copier is 5 WT%. The TD sensor output forthis toner density is referred to as Vref. Vref of thiscopier is adjusted to 2.5 ± 0.1 volts for a tonerdensity of 5 WT% (brand-new developer) for eachof the C, M, Y, and K toners. When developersare replaced, since TD sensor fluctuations canoccur in such a case, it is necessary to initializethe TD sensor and adjust its gain using SP3-005-1through SP3-005-5.

Relationship between toner density and TDsensor output



TD Sensor Noncontact CouplerInterfacing the toner density sensors in a revolvermechanism presents a special design problem.Models A257 and A269 handle this with amechanism called a noncontact coupler.

Each of the four development units has a TDsensor [A]. These sensors interface with the CPUthrough a single interface—the noncontactcoupler. The noncontact coupler has two parts;one is mounted on the main unit [B] and the other[C] is inside the bearing ring of the revolver. Thesetwo sections are separated by an air-gap.

Power for the revolver side is provided through acircular coil [D] (a small transformer) inside thecoupler sections. The power transformation is:

38 Vac (main unit) ! 12 Vac (revolver) ! 12 V(for TD sensor).

The TD sensor output is conveyed through opticalcommunication. The CPU receives TD sensoroutput only from the development unit at thedevelopment position.

[B][C]

[A]

[D]


Color Processes Color Image Transfer

Color Image Transfer

Image transfer in color machines is morechallenging than in single color copiers or printers.The image must be developed and thentransferred once for each color. Each of the colorseparations must be transferred and overlaid toachieve the complete colored copy or print. Ricohproducts have two basic methods of transferringthe developed color separations.

The most common method is a two step transfersystem. In the first step, each of the color separa-tions transfers from the OPC to an intermediatesurface. The complete image builds on the inter-mediate surface one color at a time. Once thecolor image is complete, it is then transferred tothe paper.The OPC can be either a drum or a belt. When itis a drum, the intermediate surface is a “transferbelt”. (Schematically illustrated to the right.) Whenit is a belt, the intermediate surface is a “transferdrum”.

Transferbelt

Paper

OPC drum

Two step image transfer



The other method is to transfer the colorseparations from the OPC drum the paper as theyare developed much in the same way as in singlecolor imaging systems. This is repeated for eachcolor to build the complete image directly on thepaper. This is the method used in analog colorcopiers and in tetradrive systems.

The following sections examine examples of bothmethods.

Paper

OPC drum

Direct-to-paper image transfer



Two-step Color Image Transfer

The two-step transfer method builds the completecolor image before transferring it to paper. Each ofthe color images (color separations) is firstdeveloped on an OPC and then transferred fromthe OPC to an intermediate surface. Once thecolor image is complete, it is then transferred tothe paper. This method has the followingadvantages over direct transfer to paper.

• It reduces paper handling (less chance forslipping, wrinkling, jamming, etc.)

• It allows greater control over the electrostaticsof image transfer and more precise registrationof the color separations.

• It is possible to increase the copy speed bydesigning the system so that more than oneimage can be made at a time. The illustration tothe right (model A269) shows two images beingcreated on the transfer belt.

KC

Y

M

1std

2nd

Two A4/LT images made in onerevolution of the transfer belt




The image transfer mechanism of modelsA257/A269 is illustrated to the right. Thismechanism uses two transfer belts—an imagetransfer belt and a paper transfer belt. The copiertransfer belt system first transfers the 4 color tonerimages from the drum to the image transfer beltand then later transfers the complete image ontothe paper. This permits image transfer to thepaper in a single operation.

For the paper transfer step, the copier employs aninsulated transfer belt system to improve theefficiency of image transfer to the paper. Thepaper transfer belt also provides smooth papertransport as the paper passes through the imagetransfer area and receives the image.

1. OPC drum2. Transfer belt bias roller3. Image transfer belt (ITB)4. Belt mark sensor5. Transfer belt drive roller6. Transfer belt tension roller7. Paper transfer counter roller8. Paper registration rollers9. Paper transfer tension roller10. Paper transfer belt (PTB)11. Paper transfer bias roller12. PTB blade counter roller13. PTB cleaning blade

14. PTB cleaning brush15. PTB back brush16. Belt discharge corona

unit17. Paper transfer drive

roller18. Pick-off plate19. Separation corona unit20. ITB blade counter roller21. ITB cleaning blade22. ITB lubricant brush23. ITB lubricant bar24. Ground roller



Direct-to-paper Color Image Transfer

Direct-to-paper transfer of color images is an older method that can be found in analog color copiers. It is alsoused in the unique tetradrive design.

Example 1: Model A072 (Analog)The illustration to the right shows the image transfermechanism of model A072.This model uses a transfer drum, which rotates incontact with the OPC drum. Copy paper is fed andclamped to the transfer drum. The transfer drum thenmakes the necessary number of rotations to transfereach color to the paper.The transfer corona unit is located inside the transferdrum unit. A high negative charge is applied to thetransfer corona wire and the corona wire generatesnegative ions. The negative ions are applied to thecopy paper and the negative charge attracts thepositively charged toner away from the drum and ontothe paper. At the same time, the copy paper iselectrostatically attracted to the surface of the transferdrum.When full color image is complete, the clamp releasesand the paper separates from the transfer drum.

[B]

[C]

[D]

[F][F]

[G]

[A]

[A] Transfer drum[B] OPC drum[C] Transfer corona unit[D] Separation corona unit

[E] AC discharge corona units[F] DC discharge corona units[G] Transfer drum cleaning unit

[E]

[E]



Example 2: Models A092/A105 (Tetradrive)

The image transfer method of the tetradrivesystem is different from all other color systems. Ituses a standard corona transfer system repeatedfour times. Transfer coronas [A] are located beloweach drum to pull the toner image onto the paper.

The transfer belt position lever [B] raises thetransfer belt to the drum to prevent void imageproblems under high humidity conditions.

Continued on next page.

[B]

[A][A]

[A][A]

C Y M K



The transfer corona units for all four colors are thesame, except for the corona wire height. Thecorona wires for yellow and cyan are installedcloser to the drum than those for black andmagenta [A].

The potential at the paper surface is increased insteps as each color is developed [B]. This isnecessary because the top layers of toner requirea stronger transfer force than the bottom layers.

The transfer corona current for each color is asfollows:

Black: 300 µAMagenta: 400 µAYellow: 350 µACyan: 600 µA


Color Processes Image Files

Image Files

Instead of being printed immediately, scanned data can be stored as an image file for later use. As agrowing number of machines produce or use these image files, a basic understanding of file typesbecomes increasingly necessary.

Raster vs. Vector

There are two basic ways to create images. Rasters are created by defining color data for each dotin the image. Images are built from a grid of dots. A crude example can be seen at the footballstadium. Fans holding up colored squares produce images for the television cameras.

Rasters are usually created by scanners or “paint” programs. They are particularly good atrepresenting textures or photo-realistic images. On the down-side, the unmodified, physical size ofthe image varies depending on the resolution of the output device. Rasters are naturally displayeddot-for-dot on the output device. If an image is 600 x 600 pixels, it will be displayed as a 1 inchsquare on a 600 dpi printer. The same image will appear as an 8.3 inch square on a 72 dpi monitor.

While most applications can force the image to appear at a user-defined size, scaling the image canadversely affect its quality. Also, file sizes are based on the number of pixels and color depth of theimage. Large, full-color raster images often result in mammoth files.

Vectors, on the other hand, do not try to define every dot. The image is created by building objectsout of mathematically defined curves and lines. These objects can be further filled with various colorsor patterns. Vector images are usually used for graphs, illustrations and technical drawings. They arecreated using “draw” programs. Vector images are easily resized without losing image quality. The



file size depends on the number and complexity of the objects—not the image size. However, mostoutput devices display images as rasters, so vector images need to be rendered (rasterized) beforethey can be displayed.

Metafiles represent a third option for storing image data. A metafile is not a new type of image—rather it is a composite. It is created from a combination of vector images, raster images and text.

The rest of this section will focus on raster images. Since most of our images will be created fromscan data, raster images are the most important for our purposes.

Color Depth

Images are often described by their color depth—or the amount of information stored in each dot.The larger the color depth, the greater the variety of colors available. For example, in a 4 bit colorimage, each pixel must be one of 16 different colors. An 8 bit image allows 256 different colors. Mostfull color images are 24 bit (16 million colors) or greater.

Sometimes the color depth is listed as bits/channel. PhotoShop, for example, supports 8 and 16bits/channel RGB images (x 3 channels = 24 and 48 bit color).

Color depth greatly affects the image file size. All other things being equal, a 24-bit color image willbe three times larger than a grayscale image, and twenty-four times larger than a black and whitebitmap.

Resolution

Raster images are also defined by their resolution, usually measured in dots per inch (dpi).Resolution depends largely on the device that will be used to display them. The typical computer



monitor has a 72 dpi resolution. Images displayed at this resolution look natural to the eye—thepixels blend into a smooth image. However, if that same image is printed on a 300-dpi color printer,the pixels will appear as visible blocks, giving the image a jagged appearance.

On the other hand, an uncompressed 300-dpi image file is 17 times larger than a same-size 72-dpiimage file. This means that, if the print-quality image was used on a web page, it could take 16 timeslonger to download.

Actually, the real-world difference would be greater still, since print-quality compression typically onlyreduces the file size by 1/2. Compression for web images often produces files 1/10 their original sizeor smaller.

For the best results, you should select an image resolution based on how the image will be used.Note, if you are using a single image for multiple purposes (for example, a web site and a brochure),it is usually best to create a separate image file for each.

Intended Use: Recommended Resolution:

Internet Use (e-mail and web) 72 dpi

Halftone Printing Printer’s screen frequency multiplied byx 1.5 (good quality) to x 2 (best quality)

Other Printing Printer’s resolution

Halftone printing refers to printers that use dithering to produce grayscale images. These printerscannot produce true shading. Rather, they create dot patterns to give the appearance of grays. Since



it takes multiple pixels to create one shaded pixel’s worth of information, the image resolution shouldbe less than the printer’s true resolution. Anything over the printer’s screen frequency x 2 is a wasteof memory.

However, when printing bitmaps (pure black and white images) or printing to a device that cancontrol the shading of individual pixels (through power modulation and pulse width modulation), eachpixel-worth of information is important. The image file’s resolution should equal the printer’s.

Remember, an image’s resolution and it’s scale go hand in hand. A 1-inch, 100 dpi image stretchedto fill 2 inches is the same as a 2-inch, 50 dpi image.

Resolution-based quality problems are often seen when people try to print images from the web orfrom a lower-resolution digital camera.

Lossy and Loss-less

Because raster images files can grow quite large, most image data is compressed. Compressionreduces the amount of memory needed to store the file. But not all compression techniques areequal.

Loss-less compression techniques carefully maintain all the details of the original image. Thecompression ratio will vary depending on the complexity of the image, but most are around 2:1. Theycompresses images by combining strings of identically colored pixels.

For example, if the image has a row of 5 blue pixels the original sequence would appear asBLUEBLUEBLUEBLUEBLUE. The compressed image data could be reduced to BLUEX5.



Lossy compression, on the other hand, sacrifices some image detail in order to get a greatercompression ratio, often up to 20:1. By using optical tricks that exploit limits in human vision, theycreate an image that is often indistinguishable from the original. However, depending on the amountof data sacrificed, the reduction in quality could become quite noticeable.

Lossy compression is usually used on the internet, where image size is crucial. When printing, thedrop in quality is more noticeable. Loss-less images are therefor recommended.

Format Highlights

The following section looks at seven of the most common image formats. This, however, is just asmall sampling. A lot of up-to-date graphics information is available on the web. If you are interested,I recommend looking at The Graphic File Format Page for technical information on a wide variety ofimage formats. The Graphic Formats frequently asked questions page provides a more detaileddiscussion of the advantages and disadvantages of the TIFF, PNG, JPEG and GIF formats.

BMPThe BMP file is one of the most commonly used formats for the Windows environment. It supports24 bit color depth and loss-less compression. A very stable bitmap format; however, support is verylimited on Apple or Unix systems. On Windows machines, it is used both for screen display (windowswallpaper) and printing. It is not typically used on the web.

EPSEncapsulated PostScript (EPS) files use the Adobe PostScript language. They can store eitherbitmaps or vector information. The files are accepted on virtually all platforms, and virtually all


http://www.dcs.ed.ac.uk/home/mxr/gfx/2d-hi.html

http://www.cywarp.com/FAQ_TimeCapsules.asp?goto=205


graphics, illustration and page layout applications. The format also offers a variety of options for high-quality printing to postscript printers.

Most applications cannot read the postscript information directly—therefor the file also contains alow-resolution (often binary) thumbnail image. Thumbnails are usually TIFF or PICT format. Theseimages are displayed as placeholders in many graphics and page layout programs.

There are three cautions when using EPSs. First, the PostScript may contain references to fonts. Ifthe EPS was created on a different computer, those fonts may not be available on the currentsystem. This can cause a variety of printing problems, from font replacements to print errors. Also,this may not be obvious when viewing the image in the page layout application.

Second, some thumbnail images are more accurate than others. What you see on the screen is notnecessarily what you get out of the printer. Be sure to test print and check any EPSs.

Finally, EPSs are an excellent format when working with PostScript printers. However, if the printercannot use PostScript information, the application will send the low-resolution thumbnail imageinstead. The result is very poor quality output from what was supposed to be a high-quality imageformat.

The bottom line is, EPSs provide an excellent format for high-quality printing when used properly.However, they require a bit more care and technical know-how.

GIFAn older format, the Graphics Interchange Format (GIF) only supports indexed color (8 bit, 256colors) and LZW compression (loss-less compression). Once commonly used for onlinephotographic images, it has largely been replaced by the JPEG. However, the loss-less



compression, the limited color range, and the ability to have transparent backgrounds makes it anideal choice for web-based icons, or any web-images requiring small, clear text or using only alimited number of colors. When saving rasterized line drawings, GIF files are often much smaller andmuch cleaner than JPEGs.

JPEGThe Joint Photographic Experts Group (JPEG) format is commonly used to display photographs andother continuous tone images on the web. It supports 24-bit color, and uses a lossy compression togreatly reduce the file size. While most loss-less compression averages around a 2:1 ratio, JPEGscan achieve 10:1 to 20:1, often without any visible loss in quality.

When saving a JPEG you can set variable amounts of compression. More compression results in asmaller file—but there is a greater loss in image quality. The maximum quality setting usuallyproduces a result indistinguishable from the original.

While JPEGs are an excellent choice for screen-viewable photographs, it does not handle largeareas of a single color or sharp edges very well. Blocks of color often develop odd distortions orsquiggles, while text tends to appear blurry. It is also not recommended for binary (pure black andwhite) images.

Printing tends to bring out the worst in a JPEG. The optical tricks it uses to compress the data aremore noticeable on the printed page.

One final note about JPEGS, they lose quality every time you open, edit and save them. Whilesaving it once or twice may not be noticeable, continually editing and re-saving the file can result in a



considerable loss of quality. If you are going to need to edit an image, create a master copy using aloss-less format. After you are done editing that copy, convert it to a JPEG.

PICTThe PICT format is popular with Macintosh graphics and page-layout applications. It supports 16 or32 bit color and loss-less compression. It can also support various JPEG compressions. PICT filescan store either raster or vector data. While well supported on the Macintosh, it has very limitedsupport on other systems.

PNGThe Portable Network Graphics (PNG) format was developed as a patent-free alternative to the GIF.It supports up to 48-bit color and transparent backgrounds without jagged edges. Unfortunately, olderbrowsers may not support PNG images.

TIFFThe Tagged-Image File Format (TIFF) is a flexible bitmap image format supported by virtually allpaint, image-editing and page-layout applications. It is also platform independent—being wellrepresented on Windows, Macintosh and Unix. This makes it an excellent choice for cross-platformor cross-application projects. If JPEG is the default web graphic format, TIFF is the default forprinting. It supports up to 24-bit color and a variety of loss-less compression routines. Unfortunately,its flexibility can become a liability. There are many different flavors of TIFF, and not all applicationssupport all formats.

If you run into TIFF compatibility problems, try re-saving the file without any compression. While thisproduces a larger file, it can be read by almost all image-handling applications.


DDiiggiittaall DDuupplliiccaattoorrssOverview

Digital duplicators are designed to provide inexpensive, large-quantity duplication services. They use digitally-created stencil masters and ink to make prints.

Digital duplicators are a modern adaptation of an older technology. The basic rotary stencil processwas developed in the 1930s. Before the electrostatic copy process was introduced, the reproductionof documents in the office was manly done with carbon paper (for about five copies) and stencilduplicators (for larger volumes). While much of this work has been shifted to copiers, digitalduplicators still provide a high-volume, inexpensive printing option.

Most printing methods, such as lithography, apply a specificamount of ink to the paper. The stencil process used bydigital duplicators, however, requires the ink to pass throughthe master before it is applied to the paper. While stencilmasters are very easy to make—it is difficult to control theamount of ink passed to the paper. Fortunately, advancesover the last two decades have made modernDigital duplicators easier to use, while greatlyimproving their print quality.

Compared to photocopiers, the printing speedfrom a single original is much faster. The C235

OverviewDuplicating ProcessInk Supply ControlThermal Head ControlSpecifications


Digital Duplicators Overview

supports 5 different printing speeds, ranging from 60 sheets/minute to 120 sheets/minute. Mostdigital duplicators can also use a variety of ink colors. On the other hand, the setup time for eachoriginal is longer, and digital duplicators tend to require more-complex mechanical components tohandle tasks like ejecting old masters and wrapping new masters around the drum.

While many digital duplicators are marketed towards schools, small government offices, and anyonewho needs inexpensive, high-volume printing, the high quality machines can even handle some ofthe work usually done by offset printers.


Digital Duplicators Duplicating Process

Duplicating Process

1. Master Ejecting: Ejects the used master wrapped around the druminto the master eject box.

2. Scanning: Scans the original image with the CCD through themirrors and the lens.

3. Master Feeding: Converts the image signal read by the CCD intodigital signals and sends them to the thermal head towrite the image on the master. The master thenwraps around the drum.

4. Paper Feeding: Sends paper to the drum section.

5. Printing: Presses the paper fed from the paper feed sectionagainst the drum. This transfers ink to the paperthrough the drum screen and the master.

6. Paper Delivering: Peels off the printed paper with the exit pawls and airknife, and ejects the paper onto the paper deliverytable.



Master Ejecting

To keep the ink from drying, the master remainswrapped around the drum. Therefore, the first step inthe duplicating process is to eject the old master.

When the start key is pressed, the drum rotates fromthe home position to the master eject position. Thenthe drum master clamper (A) opens.

Master pick-up rollers (B) grab the leading edge ofthe master, and remove the master from the drum.The master is ejected.

Once the master is fed completely into the mastereject box, a pressure plate compresses the masterinto the box.

After ejecting, the drum rotates into the mastermaking position.

A

B



Scanning

Scanning and image processing for digital duplicators is basically the same as other digitalprocesses. Older machines tended to use a pass-through scanner, where the image was moved pasta stationary CCD or CIS. This is the same method commonly used by fax machines—in fact, theduplicators often used the same components as the fax line. Newer machines tend to use a bookscanner—the type of scanner used on a copier. Again, the components are identical to those usedby the digital copiers.

For example, the C231 and the A265 use identical scanners.

See Digital Scanning for more information.



Master Feeding

The masters are made from a low-fiber content papercoated by a thin layer of heat-sensitive film. Thepaper is fed from a roll to the thermal head. Here,image data from the CCD is burned into the film,creating the new master.

The master is then fed to the drum. Once the drumrotates into the master feed position, the masterclamper opens, and the leading edge of the master isfed under the clamper. The clamper then closes onthe leading edge.

The new master is wrapped around the drum, as itslowly rotates. When the master making process isfinished, the master feed motor turns off, and thecutter activates. After the master is cut, the drumrotates again to wrap the remaining portion aroundthe drum.

[B]

[C]

[A]

A: MasterB: DrumC: Clamper



Master Buffering

As the master passes the thermal head, the thermalhead burns the image data into the thermal head. Inan unbuffered machine, the master is transporteddirectly to the drum. As the image is created, it isimmediately clamped onto and wrapped around thedrum.

This process can take a significant amount of time,especially for higher-resolution printers. Also, theprocess does not begin until the old master hasbeen completely ejected, and the drum has rotatedinto the master making position.

In order to improve the first print speed, many of thehigher-end duplicators buffer the master, allowingthem to start creating a new master while the oldmaster is being ejected. Old master creation andmaster ejection begin at almost the same time.

In master buffering, the new master is fed until theleading edge is past the master feed control rollers.The master feed control rollers then stop. Themaster vacuum fans activate, drawing air down themaster buffer duct.

[B]

[C][D]

[A]

A: Thermal HeadB: Master Feed Control RollersC: Master Vacuum FansD: Master Buffer Duct



As the master is created, the slack is drawn into the master buffer duct. When the drum rotates intothe master creation position, the master feed control rollers activate again. The leading edge isclamped onto the drum, and the master is fed out and wrapped around the drum.

Paper Feeding

Digital duplicators use standard paper handling processes. See Paper Feed for more information.



Printing

There are two variations on the printing process. Oneuses a pressure roller, the other uses a pressurecylinder. The basic procedure, however, is similar.

As the paper is fed, the pressure roller (or pressurecylinder) presses it against the drum.

The drum itself consists of a cloth screen over a metalscreen. The ink pump supplies ink from the inkcartridge into the drum through the drum shaft. The inkroller and doctor roller spread the ink evenly over thescreen. Ink seeps through the master where the filmhas been burnt away, transferring the image to thepaper.

The pressure roller is a smaller roller, held against thedrum by tension springs. It is attached to a camsystem, so it can disengage from the drum, and allow the master clamper to pass.

The pressure cylinder is a much larger roller—it is the same diameter as the drum. The pressurecylinder and the drum rotate in synch. The cylinder has a slot which the clamper fits into as it rotatesthrough the printing nip. This allows the clamper to pass through without disengaging the cylinderfrom the drum. So, while the cylinder takes up more space, it also simplifies the mechanical design.

[B]

[C]

[A]

A: DrumB: Ink RollerC: Pressure Cylinder



Finally, on some of the higher-end machines, a drum idlingroller has been added. This enables the Quality Start mode—ensuring that the first print has enough ink, even if themachine has not been used in a long time. When QualityStart mode is selected, the drum idling roller is loweredagainst the drum, providing ink onto the screen and masterbefore printing begins. Note: there must be a master on thedrum—if there is no master, this procedure is skipped.

Some Idling rollers also include a quality blade to scrapeexcess ink off the inside of the metal screen.

The drum idling roller disengages before printing begins.Actual printing proceeds as previously described.

[B]

[C]

[D]

[A]

A: Ink RollerB: Doctor RollerC: Drum Idling RollerD: Quality Blade



Paper Delivery

Paper separation takes place shortly after the leading edge passes the nip between the pressureroller and the drum. Since this is a wet process, the paper has a tendency to stick to the drum. Mostmachines use both air knifes and exit pawls to separate the paper. Like the pressure roller, the exitpawls are also placed on cams. They disengage from the drum to allow the master clamper to pass.

Once separated, the paper is fed into the delivery tray.

Since the ink is still wet, paper transport must be handled without smearing the ink. On oldermachines, two rollers were used to transport the paper.Each roller’s position was carefully adjusted accordingto the paper size and the paper’s position on the papertable. The rollers had to catch the paper within the5mm margin along its edges.

Newer machines use a combination of rubber beltsand a vacuum fan to transport the paper. The vacuumdraws the paper down, holding the sheet to the belts.

Finally, the paper guide wings lift the side of the paperas it leaves the delivery unit. This stiffens the paper sothat the leading edge will not sag and brush againstthe sheets already on the delivery table. Again, thisprevents the ink on freshly printed sheets fromsmearing as the paper is stacked.

[B]

[C]

[A]

A: Rubber BeltsB: Vacuum FanC: Wings


Digital Duplicators Ink Supply Control

Ink Supply Control

Overview

Ink is pumped from the ink cartridge to the ink roller. Theink travels through the drum shaft. Holes in the shaft dropthe ink onto the ink roller.

The ink on the ink roller is squeezed by the doctor roller,spreading it into an even thickness. While printing, thepressure roller pushes paper, master, and the screensagainst the ink roller. Ink seeps through the holes in thescreens and master, and is applied to the paper.

Ink Level Detection

The ink detection pins work like the electrodes of acapacitor. The capacitance between the pins is measured.This capacitance varies depending on how much ink istouching the pins. Based on the capacitance, the ink motoris turned on and off. This way, the machine maintains aconsistent level of ink on the roller.


Digital Duplicators Ink Supply Control

Ink End Condition

As soon as the capacitance indicates that the ink level is getting low, the ink pump activates. If thecapacitance does not change within a specified time, the CPU stops the printing process and turnson the Ink End Indicator. For example, the C235 waits 40 seconds after the pump activates.


Digital Duplicators Thermal Head Control

Thermal Head Control

Overview

The thermal head is a row of heating elements—one element per pixel. The thermal heatingelements melt the over-coating and polyester film layers of the master, according to the image datasent by the CCD.

The power supply PCB applies power (VHD) to the thermal heating elements. The applied voltagevaries from one head to the next, since the average resistance of each element varies. When thethermal head or power supply PCB are replaced, the applied voltage must be set to match the valuespecified for that particular head.

When creating a new master, the amount of energy sent to the head is controlled by varying thelength of time during which power is applied. This is adjusted depending on the thermal head’scurrent temperature. If the temperature is higher, the time will be shorter. The time setting iscalculated when the Start key is pressed. It is kept throughout the entire master making process.

See Thermal Head for more information.

Thermal Head Protection

To prevent the thermal head from overheating when continuously processing a solid image, athermistor in the thermal head is used to monitor the unit’s temperature. The CPU checks for anyunusual conditions when the Start key is pressed.


Digital Duplicators Thermal Head Control

Special Handling

Pay attention to the following when servicing the thermal head.

• Remove any foreign materialsfrom the platen roller.

• Remove foreign materials.

• Do not touch the master filmsurface with bare hands.

• Connect and disconnect theconnectors carefully. Keep themhorizontal and firmly reconnect them.

• Do not touch the connector terminalswith bare hands, to prevent damagefrom static electricity.

Connector

Master

Platen Roller

Thermal Head

PSU

MPU

• Adjust the voltage supplied to match thespecified value for the thermal head.

• Do not touch the surface with barehands. If this occurs, clean thesurface with alcohol.

• Do not damage the heatingelements.

• There are some ICs inside themetal cover. Do not push thecover down.


Digital Duplicators Digital Duplicator Specific Specifications

Digital Duplicator Specific Specifications

There are several specifications specific to digital duplicators. The following are some of the morenoteworthy specifications, and can be useful when comparing the capabilities of two differentmachines.

Master Processing Time

This is the amount of time it takes to create a new master. All other things being equal, this is largelya function of the machine’s resolution. A 600 dpi machine will have a much longer master processingtime than a 400 dpi machine. However, machines that buffer the master will have a much shortermaster processing time than those that do not—regardless of resolution.

Run Length Per Master

This is the number of prints that can be made from a single master. If you need more copies thanthis, the machine will need to process the job in batches, creating a master for each batch.

Master Roll Yield

This lists the number of masters that can be created from one roll.

Master Eject Box Capacity

This lists the number of masters that can be created before the master eject box needs emptying.


Digital Duplicators Digital Duplicator Specific Specifications

Ink Recommended Maximum Storage Period

Duplicator ink has a limited shelf life. For example, the gradual evaporation of water from the ink willcause it to become overly viscous, reducing its quality. Other elements also contribute to a slowreduction in ink quality.

Printing Speeds

This is the sheet-per-minute speed from a single master. It does not take into account any masterprocessing time. Unlike copiers, digital duplicators often have several different speed settings. Lowerspeeds allow higher density prints. The greater the density of ink on the page, the greater thelikelihood of wrapping jams. The slower speeds help to compensate.

Since there is a direct trade-off between print quality and speed, several options are provided. Thecustomer can select a speed appropriate to their needs.


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Light Sources

Our products use a variety of different light sources. These range from intense sources such ashalogen lamps to relatively weak sources such as LED arrays. The light source selected depends onthe function—original exposure, quenching, etc.—and the machine design. The most important lightsources from a design point of view are those commonly used for original exposure (scanning)—thehalogen lamp, the fluorescent lamp, and the xenon lamp. The most basic characteristics of thesethree lamps are summarized in the following table.

Halogen Fluorescent Xenon

Light Intensity High Low Low

Spectrum Wide Narrow Narrow

Temperature dependency* Small Large Large

Stability at start-up Good Poor Good

Heat output Large Small Smallest†

Cost High Low Lowest†

*Dependency of light intensity on temperature †of these three lamp types.

Light SourcesSemiconductor ComponentsSensors and SwitchesClutches, Motors, and SolenoidsOther Electrical ComponentsConsumables


Standard Components Light Sources

Halogen LampA Halogen lamp is an incandescent lamp filled withhalogen gas (iodine or bromine). The halogen gassuppresses filament evaporation using a chemicalregeneration process known as the “halogen cycle”(see below). Halogen lamps have a long effectivelife and strong light output.

Characteristics• Extensive spectrometric distribution• High illumination level• Small changes resulting from the temperature of

the light source and small transient changes• Long lead time to lighting• Large electricity consumption• Large heat output

Halogen CycleDuring lamp operation, the halogen gas combines with tungsten molecules that have evaporated offthe filament. The evaporated tungsten molecules are then deposited back onto the filament, insteadof on the lamp wall. Consequently, there is almost no reduction of light output from lamp walldarkening. Some light reduction from filament degradation does occur, but it is significantly lowerthan in other incandescent lamps. The halogen regenerative process requires that tungsten-halogen

halogen.pcx



lamps operate at an extremely high temperature, which slightly increases lamp efficiency, andproduces bright light and high temperatures. To withstand these high temperatures, tungsten-halogen lamps usually have quartz glass walls. Halogen lamps with quartz walled bulbs must behandled carefully. Quartz materials are extremely sensitive to oil and dirt from human skin, which cancause bulb wall deterioration, and premature lamp failure.

ApplicationsThe intense light and wide spectral output of the halogen lamp suit it to color copiers and high-speedcopiers. However, as it consumes a lot of electricity and undergoes drastic rises in temperature, it isgenerally not used for low-speed copiers and single scanner models. Since halogen lamps output alarge amount of heat, they are also commonly used as a heat source in fusing units.



Fluorescent Lamp

A fluorescent lamp is a closed glass tube that haselectrodes at each end and an internal coated surface ofa phosphorous material. The tube is filled with argon gas(or argon/krypton gas) mixed with a small amount ofmercury vapor. When a suitable high voltage is appliedacross the electrodes, an electric arc forms and theresulting current ionizes the mercury vapor. The ionizedmercury emits ultraviolet radiation, which strikes andexcites the phosphor coating, causing it to glow andproduce visible light.

Characteristics• Has a medium luminance• Produces excess heat from filaments• Short lead time to lighting• The exact makeup of the phosphor coating determines the color

properties of a fluorescent lamp’s light output.• The intensity of illumination changes depending on the tube

temperature.• Uneven illumination at the ends of the tube requires shading

plates.

Fluorescent lamp

Lamp heater

fluorsnt.pcx

FL operation (Illustration source unknown)



ApplicationsFluorescent lamps are suited for use in low-speed color copiers as well as medium-speed black andwhite copiers. They are the most commonly used type of lamp in fax machines. However, the lightquantity changes depending on the tube temperature; and a lamp heater may be included to solvethis problem.Some Ricoh machines use a variation of the fluorescent lamp, called the cold cathode fluorescentlamp (sometimes called CFL or CCFL), as a quenching lamp or pre-transfer lamp. CFLs are alsosometimes used as the exposure lamp in image scanners.



Xenon Lamps

A xenon lamp is a tube filled with xenon gas. When a voltage is applied across the lamp terminals,the xenon gas ionizes and current flows through the gas, which emits light. The terminals do nothave to be preheated, unlike in fluorescent lamps.

There are different kinds of xenon lamp. The xenon lamps used in black and white digital machinesoutput a yellowish-green light with a peak at 543 nm. The xenon lamps used with color machinesutilize fluorescence as well as gas discharge to produce white light.

The xenon lampused in model A250



Characteristics• Medium brightness light output• Less expensive than fluorescent or halogen lamps• Good durability—generally can be expected to last the life of the machine• Low heat output—exposure cavity cooling isn't required• More compact than fluorescent lamps

ApplicationsXenon lamps can be used as exposure lamps for printers, lower speed copiers, fax machines, andscanners.

Recently, xenon lamps have been increasingly used in digital products. This is mainly due toimprovements in the spectral sensitivity of CCDs, which allows use of the more economical xenonlamp.



Xenon Flash Lamp

The xenon flash lamps used in officemachines are basically the same asthe flash lamps used in photography—only larger. A xenon flash lamp hasmain electrodes at both ends of a gastube, which contains xenon (Xe) gas.(Generally, any noble gas will work in aflash lamp. However, gases other thanxenon are rarely used.) The lamp alsohas trigger electrodes, generally in theform of a wire, or conductive coating inthe lamp tube wall.

The typical xenon flash lamp circuit consists of four parts: (1) power supply, (2) energy storagecapacitor, (3) trigger circuit, and (4) the flash lamp itself. It operates as follows:

• The energy storage capacitor connected across the flash lamp is charged by the power supply.(The energy storage capacity is quite large.)

• A separate small capacitor is charged to generate a trigger pulse.

• The charge on the trigger capacitor to is dumped into the primary of a pulse transformer whosesecondary is connected to the trigger electrodes. The pulse generated by this trigger is enoughto ionize the xenon gas inside the flash lamp.

xenon.pcx



• The resistance of the ionized xenon gas is very low and the energy storage capacitordischarges through the flash lamp, which then emits a brilliant burst of light.

Characteristics• Produces an intense peak of radiant energy.

• Since flash lamps use a high voltage, precautions must be taken against electric shocks.

ApplicationsXenon flash lamps are suited for use in high-speed black-and-white copiers. They are alsooccasionally used as the heat source for flash fusing.



Neon LampsLike the cold cathode fluorescent lamp, a neon lamp uses a cold cathode to excite the atoms of agas in an enclosed tube. However, the light is emitted by the neon gas in the tube rather than by aphosphorous coating inside the tube. The neon gas gives an orangish-red light.

ApplicationsIn Ricoh products, neon lamps are used only as quenching lamps.



LED ArraysLED stands for light emitting diode. As the nameimplies, an LED is a diode that emits light when asmall electric current passes through it. LEDs arecommonly used as display devices and indicators(see the next section), but they can also bemounted together in an array and used as a lightsource.

Characteristics• LED arrays can be wired so that the LEDs can be

turned on/off in blocks to provide preciseillumination.

• LED arrays are useful where compact componentsare required.

ApplicationsIn Ricoh products, LED arrays are used for documentexposure in small fax machines and scanners. Theyare commonly used as quenching lamps in analog anddigital copiers. Also, most analog copiers use them forerase lamps. The illustration to the right shows an LEDarray [A] used as an erase lamp in a copier. [A]


Standard Components Semiconductor Components

Semiconductor Components

This section deals with components that are based on semiconductors.

Diodes

Normal DiodesA diode consists of a p-type semiconductor joined to an n-type semiconductor. A diode only passes current in onedirection. If it is connected up as shown opposite, currentwill flow.

However, if the power source is connected up the oppositeway around, current will not flow.

+_

P N

Currentflow

Symbol:



Zener DiodesA zener diode is connected the opposite way aroundfrom a normal diode. Normal diodes cannot pass anycurrent if connected up in this way, and may bedestroyed. However, zener diodes connected inreverse will pass current, if the voltage across thediode exceeds a certain value, known as thebreakdown voltage. After the breakdown voltage hasbeen reached, the voltage across the diode will notchange much, even if the current is greatly increased.

Zener diodes can be used to make sure that the voltage ata certain point in a circuit (Vz in the above-right diagram)does not exceed a certain value. The diagram below rightis the typical diode characteristic curve. While normaldiodes should operate below the breakdown voltage andmay be damaged if it is exceeded, the zener diode isintended to operate at that voltage.

+

V VZ

Zener Diode



VaristorsA varistor acts like two zener diodes connected backto back. This means that it has positive andnegative breakdown voltages. A single zener diodeonly has a negative breakdown voltage. Varistorsare used in similar ways to zener diodes. They arealso useful in protecting circuits against voltagespikes. The example to the right shows a varistorconnected across a switch to eliminate sparking.

The illustration below right shows the characteristicdouble-breakdown curve of the varistor.

VacL



Light Emitting DiodesA light emitting diode (LED) is a kind of diode that emitsphotons (light particles) when a small electric currentpasses through it. When current flows across the pnjunction in diodes, energy is released in the form ofheat. However, the material used to make LEDs isselected so that some of the energy is emitted as light.

Light emitting diodes have some special characteristics.They convert electrical current directly into light;therefore, the LED is more efficient than many otherlight sources. Also the light emitted by an LED has anarrow wavelength range.

The LED is enclosed in a transparent case of epoxyresin or plastic. The typical LED produces red orinfrared light; however, there are varieties to producemany colors. Alternately, as shown in the illustration, acolored case can be used to modify the light output.

LEDs can be used to form large displays and are oftenthe lighting elements in information displays used inpublic places such as highways and airports. In officemachines, LEDs are used to light indicators onoperation panels, as indicator lights on circuit boards,and in LED arrays.

P

N

Symbol:

+_

P N

Currentflow

A small PCB with indicator LEDs on it.



Laser Diodes

Natural light is a mixture of light of differentwavelengths. However, a laser beam consists oflight at one wavelength, and the waves are all inphase (the peaks and troughs in the waves allcoincide).

As the waves are all in phase, the light is veryintense (if peaks and troughs do not coincide, theytend to cancel each other out, reducing the powerof the beam).

Natural light can be focused, but it cannot befocused to so fine a point as laser light can. Thisis because a lens at the same angle does notrefract the different components of natural light,having different wavelengths.

To the right is a simplified diagram of a laserdiode. Laser diodes can be considered as similarto LEDs in operating principle; current flowingacross the pn junction causes energy to beemitted in the form of light. LEDs emit light in alldirections. However, the pn junction in laserdiodes has a mirror at each end, reflecting thelight back into the diode. When the current

+ _

Currentflow

P N



Laser diode LD Unit

passing through the diode reaches a thresholdvalue, the light reflected back into the junctionstimulates more atoms in that region to emit moreradiation of the same wavelength. Some of thislight passes out of the diode through one of themirrors, which is partially transparent. The lightbeams emerge from the mirror parallel to eachother.

The wavelength of the laser depends on thecomposition of the semiconductor material. Thelasers used in most printers emit red light.Engineers are trying to develop lasers that emitgreen or blue light; the shorter wavelengths of thislight would allow smaller dots to be written to thephotoconductor, leading to higher resolutionprintouts.

For More Information

For a brief introduction to laser theoryand more information on laser diodeswe suggest you reference A BriefIntroduction to Laser Diodes at theUniversity of Washington web site(http://www.ee.washington.edu/class/ConsElec/Chapter6.html)*.

*We have no control over this web page. The content orlocation may change at any time.



Transistors

Bipolar Junction TransistorsA bipolar junction transistor contains two junctionsbetween p and n type semiconductor, and threeelectrodes (the collector, the base, and theemitter). The most common use of a transistor isas a switch. They are also used in amplificationand rectification. There are two types of transistor:the npn transistor, and the pnp transistor. The npntransistor is the most commonly-used of these.

The diagrams to the right show the symbols forboth types of transistor, their construction, and thedirection of current flow. Notice that the batteriesin the pnp transistor circuit are connected up theopposite way round from the npn transistor.

(Continued on next page.)

PNPType

NPNType



In the diagram on the right, an npn transistor iscontrolling a lamp. A positive voltage is appliedbetween the collector and the emitter. The lampcannot switch on unless a voltage is also appliedbetween the base and the emitter.



PhototransistorsA phototransistor works like an ordinary bipolartransistor, except that the transistor is switched onby light shining on the base region of thetransistor. The diagram on the right shows an npn-type phototransistor.

In office machines, phototransistors are used inphotointerrupters, optoisolators, and reflectivephotosensors.


Standard Components Sensors and Switches

Sensors and Switches

Reflective Photosensors

Reflective photosensors are short range sensors thathave a light emitting element (usually an LED) and alight sensitive element (usually a phototransistor).Reflective photosensors work by bouncing light off ofan object.

There are two main types of reflective photosensor.The simplest type signals the presence or absenceof an object or condition—the presence of paper, thepresence of a belt reference plate, the presence of acassette or cartridge. The illustration to the right is anexample. This type of sensor has a binary output; itis either activated or deactivated.

The other type of reflective photosensor is used togather information about the surface being sensed. Ithas a variable output that depends on the strength ofthe light striking the light sensitive element. Theprimary example is the image density sensor (or IDsensor) used in copiers and other products.



Characteristics! Small, inexpensive, rugged! Available in many different types (size, shape,

sensitivity, specifications).

ApplicationsReflective photosensors are used for detectingpaper in the paper path, paper size detection,master belt position detection, and a number ofother functions.

A reflective photosensor



ID Sensor

The ID sensor is a special application of thereflective photosensor. Two types of ID sensor areused as part of the process control system inphotocopiers.

One type is a direct reflection ID sensor. It ispositioned so that light from the LED reflectsdirectly to the detector. This is the commonly usedtype of ID sensor.

The other type is a diffused reflection ID sensor.In addition to the light reflected at a direct angle,diffuse light reflects at all angles from the toner onthe drum. This sensor detects image density byreceiving some of this diffused light. Using thistype of sensor improves the measurementaccuracy of the sensor pattern densities—particularly for yellow, cyan, and magenta toners.

DirectreflectionID sensor

Drum

Toner

LEDDetector

LED

DiffusedreflectionID sensor

Diffuse light

Drum

Toner

Detector



Photointerrupters

A photointerrupter consists of an LED and aphototransistor separated by a slot. The sensordetects when something enters or leaves the slot,such as an actuator, a part of the machine, or asheet of paper.

When there is no actuator in the slot, light fromthe LED activates the phototransistor, and currentflows through it. However, if an actuator enters theslot, light from the LED is blocked and currentcannot pass through the phototransistor.

Photointerrupters have a variety of uses in officemachines. They are commonly used as homeposition detectors for moving parts such as lensesand scanners and to detect paper as it movesthrough the paper feed path. In machines such asphotocopiers that handle a variety of feed stockphotointerrupters are generally preferred overreflective photosensors because photointerruptersare not affected by the reflectivity of the paper.

Continued on next page.)



Characteristics! Small, inexpensive, rugged! Available in many different

types (size, shape, sensitivity,specifications).

Most photointerrupters that are used as paper detectorsuse a "feeler" type plastic actuator. However, a photo-interrupter is occasionally installed across a paper feedpath, as shown above. This type of photointerrupter maybecome dirty and will need cleaning periodically.

A photointerrupter [A] used as a homeposition sensor. Notice the scanner drivewire below the slot of the photointerrupter.

[A]

Photointerrupters: The one on the left has aweight operated actuator built on it.



CCDsA CCD (Charge Coupled Device) is asemiconductor chip with light receiving elementsetched onto it. In a digital machine that scansdocuments, the CCD is a row of these elements;each element on the CCD corresponds to onepixel on one main scan line across the original.The CCD also contains circuits for transferring theaccumulated charges out of the elements and intothe video processing circuits.The diagram on the right shows a simplified cross-section of a CCD element. When applying theappropriate voltage across the element, any lighthitting the element liberates electrons from thesilicon at the boundary between the n and p typesemiconductors. Positive charges can flow out, butan insulating layer traps the electrons, and gathersthem under the electrodes. The brighter the lightshining on the element, the more electronsgenerated in that element.

T1 T2 T3

Light sensitiveelements

Charge transfer circuitsOutput

Charge transfercontrol signals

N

P

_

+



After scanning a line, the charges trapped ineach element must be moved out of theCCD and into the video signal processingcircuits so that the next line can bescanned. The diagram shows how this isdone.

The diagram shows two adjacent elements.Each element has three electrodes attachedto it. After scanning a line of data, theelectrons are under electrode 1, as shownin the top diagram.

A voltage V2, higher than V1, is thenapplied to electrode 2. The electrons areattracted to the area beneath electrode 2,as shown in the middle diagram.

Then, the voltage at electrode 1 switches offand the voltage at electrode 2 is set to V1,as shown in the bottom diagram. Theelectrons all gather under electrode 2.

By repeating the above procedure, butusing electrodes 2 and 3 instead ofelectrodes 1 and 2, the electrons move to

__ __ __ __

T1=V1

T2=0

T3=01 2 3 1 2 3

T1=V1

T2=V2

T3=01 2 3 1 2 3

__ __ __ __

T1=0

T2=V1

T3=01 2 3 1 2 3

_ _ ___ ____ _ ___ ___



electrode 3. The result of this is that one element shifts all the charges along, and the elementcharges at the end of the CCD shift out of the CCD. By continuing this process, all the charges shiftout of the CCD. The series of charges appears on the CCD output line as a serial analog videosignal. This signal passes to the video processing circuits, allowing the next line of the original to bescanned.



Contact Image Sensors (CIS)

The contact image sensor (CIS) is a compactimage reading assembly containing an LED array,an array of self-focusing optic fibers (SELFOC),and a strip of light detectors, such asphototransistors. The CIS is used instead of theCCD in the most compact of fax machines.

The illustration to the right (from model H545)shows a typical CIS. Light from the LED array [A]reflects off of the document, through a row of self-focusing optic fibers [B], and onto a strip ofphototransistors [C]. The entire assembly islocated directly below the document, so a longlight path is not necessary.

When using a fluorescent lamp/lens/CCDarrangement, the light path is typically about 300to 500 mm. However, with a CIS, the light pathcan be reduced to about 15 to 50 mm; with themost recent types, the CIS is positioned less than0.1 mm from the surface of the document.

[B]

[C]

[A]



Hall Effect Sensors

Hall effect sensors are used in some networkcontrol units (NCU) of fax machines to detect linecurrent. The output of a Hall effect sensor is calledthe Hall voltage. If a conductor [A] is placed in amagnetic field [B], and current [C] flows throughthis conductor perpendicularly to the magneticfield, a Hall voltage (VH) is generated across theconductor.

The conductive material in Hall effect sensors isnormally a semiconductor, as the Hall effect is toosmall to measure accurately in metallicconductors.



Thermistors

A thermistor is a device that undergoes a verylarge change of resistance with temperature. Thename is derived from thermally sensitiveresistor. Typically, a thermistor is made from asemiconductor or sintered metal oxides.

Most types have a negative temperaturecoefficient—that is, the resistance decreases asthe temperature increases. However, somepositive temperature coefficient varieties are alsoavailable. The material can be formed into rods orsmall beads, but for sensing purposes the smallbead shape is generally used in order to get thefastest possible response.

Thermistors have a large variety of uses. In officemachines, they are used mainly to measure thetemperature at critical points—for example insidefusing units or optic cavities.

Thermistors [A] used to measure thetemperature of fusing rollers (model G024)

[A]



MicroswitchesMicroswitches are electromechanical devices,which contain two contacts. They are modular,inexpensive, resistant to dust and contaminationas well as metered. This means that any time theactuator is depressed, the contacts of the switchwill close at the same point each time. Theseswitches have a characteristic sound or click whenthe contacts close. The main advantage of amicroswitch is its durability and its consistency.

Above pictures courtesy of Zippy USA Inc.

FP = Free PostionOT = OvertravelOP = Operating PositionPT = PretravelRP = Release PositionMD = Movement DifferentialOF = Operating Force

The “normally open”terminal of this switchhas been removed sothat it cannot beconnected incorrectly.



Reed SwitchesReed switches are magnetically operatedcomponents with contacts hermetically sealed in aglass capsule. Bringing a permanent magnet tothe switch or placing the switch in or near anelectromagnet causes the contact “reeds” to flexand touch, completing the circuit. Either protectiveinert gas or a vacuum within the capsule keepsthe contacts clean, protecting them for the life ofthe device.

Due to their lack of mechanical parts, reedswitches are maintenance-free and remainunaffected by temperature change, moisture,chemicals, dust, abrasive fluids and other hostilesurroundings.

Features:• Reliable• Non-mechanical• Long operating life• Compact• Rugged



ThermoswitchesAs the name implies, a thermoswitch (also known asthermal switch or thermostat) is a temperaturecontrolled switch.

Thermoswitches have contacts made of twodissimilar metals molecularly bonded together.These are called bi-metal contacts. The two metalsexpand and contract at different rates with changesin temperature. As the temperature rises the bi-metalcontacts start to flex, and at a certain temperature,the contacts will open. At a lower, temperature, thecontacts will close again.

The difference between the opening and closingtemperature of a thermoswitch is the "hysterisis" or"differential" of the device. Some thermoswitches,such as those used in deep fat cookers or popcornmachines, have a narrow hysterisis. However, InRicoh products, thermoswitches are usuallyoverheating safety devices with a large hysterisis.For example, the thermoswitch used in the 1stscanner of model A257 opens at 140ºC but will notclose again until its temperature drops to -35ºC!

A collection of thermoswitches.(Photo courtesy of ElmwoodSensors, Inc.)

Note: Thermoswitch and thermostat are oftenused interchangeably. In fact, thermostat is theterm used in our parts catalogs. However, herewe use thermoswitch to avoid confusion withadjustable control devices such as roomtemperature thermostats.


Standard Components Clutches, Motors, And Solenoids

Clutches, Motors, And Solenoids

Clutches

Torque Limiter ClutchesIn Ricoh products, torque limiter clutches are oftenin reverse rollers of feed and reverse roller paperfeed mechanisms. In concept, torque limiterclutches (also called slip clutches) are simple.They transmit rotation to a drive component(usually a roller, pulley, or gear mounted on arotating shaft). As long as the resistance torotation is less than the torque (twisting force)limitation of the clutch, the roller turns with theshaft. If the resistance exceeds the torquelimitation, the roller stops turning—it slips. In fact,it may turn in the opposite direction if sufficientcounter force is applied.

Torque limiter structures vary: some use springsas slip mechanism, while others use magneticforce or powder filling. Compared to those thatuse springs, torque limiters that use magnetsand/or powders do not need to be lubricated with



grease or other lubricants, so that they are easierto maintain. In addition, the magnet-type torquelimiter does not generate much heat, even afterextended use, because it does not come incontact with other components. Consequently, itensures stable torque. The torque limiter of themodel A112 reverse roller, shown on the previouspage, is a magnetic type.

Here are some other examples of torque limiterclutches:

The clutch used in Model A084, illustrated to theright, uses two coupled magnetic type clutches.(Two coupled clutches have a stronger totaltorque than a single clutch.)

Continued on the next page.

Driveshaft

Rotor

Innermagnet

Outermagnet Casing

Model A084 (magnet)



Model A133 uses a magnet and ferrite powdertype slip clutch.

Model A133 (magnet + ferrite powder)

Inputhub

Outputhub

Magneticring

Ferritering

Ferritepowder



Electromagnetic ClutchesThe illustration to the right diagrams the basicparts of an electromagnetic clutch. Gear [A] isdriven by a motor. This gear is an idle gear; itdoes not drive the roller shaft [B]. Shaft [B] isattached to the rotatable part [C] of the clutch, andheld in place by an E-ring [D].

When the clutch is switched on, current flowsthrough the coil [E]. The magnetic field generatedby this coil attracts plate [F], which is connected togear [A]. The motor is still turning gear [A], andwhen plate [F] comes into contact with the rotatingpart of the clutch [C], the roller shaft begins toturn.

A typical application is shown to the right, where aclutch [A] switches on to connect shaft [B] to thedrive from motor [C].


[B]

[C]

[D]

[E] [F]

[A]



An electromagnetic clutch requires + 24 or + 12volts to drive it, but a CPU cannot output this higha voltage, so the CPU controls the clutch througha driver. When the clutch is off, the driver isholding the control signal to the clutch high,preventing current from going to ground. Whenthe CPU drops the control signal low, + 24V flowsthrough the coils in the clutch, and through thedriver to ground.



Spring ClutchA spring clutch is purely mechanical clutch. It is asimple device that consists of two separate pieces fittedinside a coiled spring. One piece called the drive hub,supplies rotation from a motor. The other piece, calledthe output hub, delivers the rotation of the drive hub toa shaft. Under normal circumstances, the spring gripsboth pieces very tightly, so they function as one unitand pass on the rotation from the motor. The clutch’srelease mechanism is a sleeve that surrounds thespring. The sleeve is attached to one end of thespring—the clutch spring tail. The other end of thespring is engaged with the output hub. When the sleeveis kept from turning, the spring expands away from thedrive hub, disengaging the drive.

The sleeve of a spring clutch either has a ratchetsurface for a pawl to engage with or one or moreprojections for a stopper to engage with.

Typically, spring clutches are engaged and disengagedby some kind of electronic control—usually a solenoid.

Sleeve

DriveHub

OutputHub

Sleeveprojection

Springtail



Magnetic Spring ClutchA magnetic spring clutch is a hybrid of theelectromagnetic clutch and the spring clutch.Unlike the normal spring clutch, the spring is loosewhile idling. When the electric coil is energized, itcauses the spring to tighten around the outputelement.



DC Motors

Electric motors are based on the following twoobservations:

• When current flows along a wire, a magneticfield develops about that wire.

• When two magnetic fields are close to eachother, an attractive or a repulsive force is felt.

So, if a wire carrying current is placed in amagnetic field, a magnetic field develops aroundthe wire, and a force is exerted on the wire. Theforce is strongest if the wire is at 90° to themagnetic field. The force is also at 90° to the wire.If there is no angle between the wire and the field,there is no force. This is summarized in thediagram opposite; the wire would be forceddirectly upwards, away from the plane of thepaper.

If a loop of wire is placed in a magnetic field, thecurrent direction is opposite on each side of theloop. This means that one side has an upwardforce on it, and the other side has a downward



force on it. This causes the loop to rotate, asshown opposite.

The part of the motor containing the loop of wire iscalled the armature. It is normally in the form of adrum, with many loops of wire wound around it forincreased motor power.

The armature is connected to the drive current bya split metal ring called the commutator, and apair of brushes made from a low-resistancematerial such as graphite.

Each segment of the commutator is insulated fromthe other. The commutator is split in a dc motor sothat the polarity of the current flowing through theloop is reversed every 180° of rotation. This allowsthe rotation of the coil to continue; if there were noreversal of current, the coil would not rotateconstantly.



Brushless DC MotorsIn the dc motor described above, the magnet isstationary while the coil rotates. In the brushlessdc motor, the coil is stationary and the magnetmoves.

In a typical example, nine coils are attached to themotor drive board, arranged in a circle around theshaft. A circular magnet, com-posed of eightalternating north and south polarized segments,fits around the outside of these coils. The magnetis bonded to a metal cover, which is bolted to themotor shaft.

As shown in the diagram, the coils are wired up sothat there are three north poles, three south poles,and three neutral positions around the center. Torotate the magnet, the motor drive board switchesthe positions of the poles in such a way that themagnet is always pulled around in the samedirection.

Ricoh products primarily use two types ofbrushless dc motors—servomotors and steppermotors.



ServomotorsServomotors use feedback to maintain a constantrotating speed. To check that a dc servomotor isrunning at the correct speed, the drive boardcontains a circuit known as a phase-locked loop.An oscillator generates a reference frequency.The circuit board contains a detector that convertsthe motor’s rotation into another frequency signal.The phase detector compares both signals; afeedback signal is sent to the motor drive board toadjust the motor speed until it reaches the correctvalue. When the motor is at the correct speed, thetwo frequencies are the same.

Rotor Stator

The same motor disassembled to show statorand rotor.

A servomotor mounted on its controller board.



Stepper MotorsStepper motors are used whenever accuratepositioning of a component is required.

The outer shell of the motor is stationary. Coils arewound around teeth attached to this shell. Thecore of the motor, made of iron, can rotate. Thearrangement of the teeth is such that, if pulses areapplied to the coils in the correct timing sequence,the core of the motor can be rotated in stepwiseincrements of a few degrees.

In the example shown here, when phase 1 isenergized, two of the teeth on the motor core willalign with the coils on the outer shell, but the otherfour teeth will be out of alignment. Then, if phase2 is energized, the core rotates by 15 ° to aligntwo of the other teeth. If phases 1, 2, 3, and 4 areenergized in sequence continuously, the motor willdrive the shaft in increments of 15 °. The order ofactivating the coils can be varied to give differenteffects, such as reverse motion, or coarser steps.



A typical steppermotor

The stator

The Rotor9 August 2003 Page 1157


Solenoids

The solenoid is one of the oldest, simplest andmost commonly used electromagnetic devices. Itconsists of a hollow electromagnet (coil) and amovable plunger that fits inside. When an electriccurrent energizes the coil, it creates an electro-magnetic force around the coil. This force causesthe plunger to move into the coil. The picture tothe right shows a disassembled solenoid.

The amount of force created by a solenoid is indirect proportion to the amount of current applied.Some other factors, such as the number of turnsin the coil, the magnetic character of the steel,and the stroke of the solenoid affect the amount offorce produced.

The solenoid drive circuit is similar to the drivecircuit for and electromagnetic clutch as explainedon an earlier page.


Coil

Plunger

Coil Plunger

Direction of motion


Standard Components Other Electrical Components

A typical application is shown to the right, wherethe solenoid’s plunger is activating a mechanicalpaper feed mechanism. A pawl [A] is gripping theratchet sleeve of a spring clutch [B], preventingmotor drive from reaching the feed rollers [C].When the solenoid [D] turns on, the plunger pullsthe pawl away from the ratchet sleeve, and therollers start to rotate.

For More Information

For more information on solenoid theory,operation, and design, we suggest youreference What is a Solenoid at the website of the Detroit Coil Company.(http://www.detroitcoil.com/whatis.htm)*.

*We have no control over this web page. The content orlocation may change at any time.

[B]

[C]

[D]

[A]



Other Electrical Components

Thermal Heads

OperationThe thermal head is the central component of the thermal printer. A thermal head consists of a rowof heating elements. If a heating element is turned on, it will heat up. The heat from the element willmake a dot on the thermosensitive printer paper.

Roughly speaking, each element on the thermal head reproduces what was scanned by thecorresponding element of the CCD at the transmitter.

There are 8 heating elements for each mm across the thermal head. A4 [8.5"] thermal heads have1728 elements, B4 [10.1"] thermal heads have 2048 elements, and A3 [11.7"] thermal heads have2368 elements.

Basically, the CPU clocks a line of data into a shift register in the thermal head. When the line iscomplete, the CPU sends a latch signal, then prints the line. Then the paper is fed forward one line,and the next line is printed in the same way.

When printing a line, the CPU divides the line into 4 blocks. It prints the blocks one at a time. Each ofthese blocks is transferred to the printing elements using a strobe signal. Each block has a separatestrobe signal.



The blocks are usually adjacent on the thermalhead, but they do not have to be. In fact it iseven possible to interleave the blocks, havingan element from block 0 next to an elementfrom block 1, then one from block 2, followed byone from block 3, then back to block 0 again,and so on across the thermal head.

Data, latch, and strobe signals reach a decoderin the thermal head from the CPU. The + 24VDsupply comes directly from the power supply; itis a separate channel from the + 24VD supplyused by the rest of the machine.

Serial data comes from the CPU on pin A (seethe diagram on the previous page). In mostmodels, for a black dot, A is high. The data isclocked into the shift registers (the clock is onpin B).

When a line of data has been fed to the shiftregisters, the CPU sends a latch pulse (pin C)and the data moves into the latches.

To print the line of data, the CPU sends strobesignals to the thermal head. First, the strobesignal for block 0 (pin D goes low) is sent to



block 0, and the data in the block 0 elements passes from the latch to the heating elements (for ablack dot, the element is heated). After all elements for block 0 have been printed, pin D goes highagain. Then blocks 1 (pin E), 2 (pin F), and 3 (pin G) are sent in sequence, in the same way as block0.

The duration of the strobe pulse determines how much an element is heated to make a black dot.The CPU monitors the thermistor on the thermal head (see section 3-5-4). The CPU calculates thestrobe pulse width based on the thermistor reading and on the value for the pulse width enteredusing service mode when the head was installed.

NOTE: In most models, the pulse width must be programmed using a service functionafter installing a new thermal head or system RAM board (called the MBU inmost fax models). In a few models, the pulse width is programmedautomatically.



Internal StructureThe internal structure of the thermal head variesfrom model to model. However, two basic typeshave been used so far. These are the discrete-element control type and the block control type.

In a thermal head using discrete-element control,each element has its own discrete clock, latch,and switching circuits. Each element also receivesthe strobe signal.

Block 0 Block 1 Block 2 Block 3

1728 Heating Elements

FCU

CPU

STROBE LATCH DATA CLOCK

Shift Register

Latch

24V

ElementHeating Element

Circuit



In a block control type thermal head, driver ICscontrol a group of elements. For example, onedriver IC may control 64 elements. The decodersends a clock, latch, and strobe signal to eachdriver IC. Each driver IC contains shift register,latch, and switching circuits for the elements that itcontrols.

A good thermal head will have a conductive coverthat is grounded to prevent build-up of static,which would damage the driver ICs inside thethermal head.

Driver IC

Latch

Shift Register

64 Heating Elements

Block 0 Block 1 Block 2 Block 3

1728 Heating Elements (27 driver ICs, 64 elements/driver IC)

7 DriverICs

7 DriverICs

6 DriverICs

7 DriverICs

FCU

CPU

STROBE

LATCH

DATA CLOCK

24V



LCDs

LCD is an abbreviation for Liquid Crystal Display. AnLCD is a digital display that consists of two sheets ofglass separated by hermetically sealed liquid crystalmaterial. The liquid crystal is normally transparent.The outer surface of each glass sheet has atransparent conductive coating, forming front andback electrodes. On the viewing side, the conductivecoating is arranged as either a matrix of dots (forexample for a computer display) or character formingsegments (for example the 7-segment displayelements of a calculator). Leads at the edge of thedisplay attach to the segments or the lines of thematrix. A voltage applied between the front and backelectrodes, causes the liquid crystal molecules tochange alignment and thus become reflective. Thereflectivity of the liquid crystal segments can varydepending on the amount of voltage applied.

Some LCDs depend on the reflection of ambient lightfor viewing. However, most larger displays use abacklight. The illustrations to the right show LCDdisplays used on model A201 (upper picture) andmodel A246 (lower picture).



Characteristics• Lightweight and thin construction

• Not naturally radiant, a light source is required.

• More expensive than CRTs (Still true … but prices are dropping.)

ApplicationsLCDs are used as display screens.

For More InformationFor more information on LCD theory, operation, and design, wesuggest you reference the following web pages:LCD Frequently Asked Questions.(http://margo.student.utwente.nl/el/misc/lcd_faq.htm)*Liquid Crystal And Other Non Emissive Displays(http://itri.loyola.edu/displays/c3_s1.htm)**We have no control over these web pages. The content or location may change at any time.


Standard Components Consumables

Consumables

Photoconductors

The photoconductor—a photoconductive drum or belt is the heart of most imaging processes. Thephotoconductor's surface is where the latent image is formed and then developed. Photoconductorshave the following characteristics:

• They are able to accept a high negative electrical charge in the dark. (The electrical resistanceof a photo-conductor is high in the absence of light)

• The electrical charge dissipates when the photoconductor is exposed to light. (Exposure tolight greatly increases the conductivity of a photoconductor.)

• The amount of charge dissipation is in direct proportion to the intensity of the light. That is,where stronger light is directed to the photo-conductor surface, a smaller voltage remains.

Our products use two types of photoconductors. One type is a selenium based inorganicphotoconductor. That type was used in the past for analog copiers. The other type is an organicphotoconductor (OPC) that is used for analog and digital copiers, plain paper facsimiles, and laserprinters. Recently, all such products use OPCs instead of inorganic photoconductors.



Organic Photoconductors (OPC)An OPC consists of a CTL (charge transfer layer),CGL (charge generation layer), electrode layer,and a substrate to which the layers are bonded.(The electrode layer is also called the underlayer.)

Ricoh made OPCs have charge generationpigments and charge transfer compoundsimbedded in the charge generation layer. Thesematerials greatly improve the responsecharacteristics of the OPC.

For more information on OPCs, refer toAppendix 2-OPC.

Cross section of OPC layer

Charge transfer layer

Charge generation layer

Electrode

CG material CT material

Substrate



SeleniumMany of the copiers in the field use selenium drumphotoconductors. These drums consist of a layerof selenium or a selenium alloy bonded to analuminum base.

Selenium drums have gone through severalgenerations of development. However, the onlytypes that you are likely to encounter in the field atpresent are types H and F. Type H has a layer ofselenium-tellurium alloy bonded to an aluminumcore. Type F has a layer of selenium-arsenic(actually Arsenic-Triselenide) bonded to analuminum core.

The F type drum is more durable and has greaterspectral sensitivity. However, it is more expensiveto make.

Selenium photoconductor types

Type H

Type F

Se-Te Layer

Al Šî‘Ì (Base)Al Core

Se-As Layer

Al Core



The sensitivity of selenium changes slightly withvariations in the temperature around the drum.This is especially true of type F drums. Under coolconditions, the drum may be excessively charged,resulting in drum has an internal over-toning of thecopy image. To prevent this, many machines havea heater to warm the drum if it becomes too cool.

Selenium drumwith a heater



Toner (Black)

Toner is a combination of plastic resins, dyes,waxes, flow agents, charge agents, and particleswith magnetic characteristics (if magnetic toner).The plastic resins are the base ingredients oftoner. They combine with some or all the otherparts (sometimes with other additives) in a precisemixture with the proper charge, transfer, andfusing characteristics required for each type oftoner.

Non-Magnetic MonocomponentAll-in-One toner that contains blackened pigmentsfor printing in a matrix of resin. This kind of tonerusually comes in a cartridge and is used with non-magnetic rollers. For this type of toner, a staticcharge picks up and holds the toner on the rollersurface.

Pigment and resin mixedtogether to form non-magneticmonocomponent toner



Magnetic MonocomponentSimilar to the non-magnetic toner, this type hasiron oxide particles encapsulated in the resinmatrix of each individual particle of toner.

The toner itself isn't actually magnetic, but the ironparticles in the toner make it possible for magneticrollers to easily pick up and hold the tonerparticles. All monocomponent systems that usemagnetic rollers must use this type of toner.

Particles of ironoxide

Pigment and resin



Dual ComponentThe toner used in dual component developmentsystems is similar to the non-magnetic typemonocomponent toner. This type of toner workswith a separate particle known as a carrier. Themixture of toner and carrier is known asdeveloper. The toner and carrier particles are heldtogether by triboelectric charges. They developopposite triboelectric charges due to mixing actionin the development unit.

The carrier rides on magnetic rollers and carriesthe toner with it to the photoconductor. The carrieritself is not transferred to the photoconductor, butmerely releases the toner onto the photoconductor(which the toner is electrostatically more attractedto) and then returns to the hopper to pick up more.The carrier is normally an iron or iron oxideparticle with a coating to improve durability.

The illustration to the right shows the toner anddeveloper particles used in F-type developer.

Coat layer (About 1 m thick) µ

Plastic resin base

Pigment

Charge control material

Carrier

Toner

Toner and carrier of F developer

Core material (diameter of about 100 m) µ



CharacteristicsThere are three main characteristics of toner: its charge properties, fusing ability, and imagecapabilities.

Charge Properties

The charge is what enables toner to transfer from its container to the drum. If the toner is notcharged properly, dirty background, toner blasting, or light prints may occur.

The characteristics of toner charge depend on the toner particle size, shape, and composition.Friction generates a triboelectric charge on the toner particles. The charge generated for eachparticle depends on the surface area to mass ratio of each particle. This is determined by the sizeand shape of the particle. The smaller the particle the larger the ratio. The result is a strongertriboelectric charge for smaller particles. Particle sorting or printing defects can occur if toner particlesare not uniformly sized. Therefore, the toner requires sifting several times after it is ground into apowder. Charge control material or "charging agents" are also important in that they help determinehow well particles charge and if that charge is negative or positive.

Fusing Ability

Fusing requires very specific adhering and melting properties. Toner must melt at the correcttemperature to be compatible with the fusing system it is in. The fusing rate is also an important partof fusing.



Toner must fuse quickly for high speed printers and slowly for lower speed ones. If the toner cannotmeet these standards cold or hot offset may occur. This is a ghost image picked up on the fusingrollers. The plastic resins and various additives determine the fusing properties of the toner.

Flow rate is also important because it determines the density of print. A toner that flows wellproduces higher density copies. Therefore, an optimum flow rate, where the toner is neither toomuch nor insufficiently fluid, is necessary. Toner composition, particle size and additives determinethis rate.

Image Capabilities

If all of the previous characteristics are correct, a problem may still occur. This problem concernsresolution. High-resolution printers require micro fine toner, usually around 6 microns or less. If thetoner particles are larger than this, the resulting image will not have the razor-sharp quality the userdesires from their high-resolution printer. The size of the particle will also effect the density of theimage and limit the number of shades the printer can produce.

Printing black dots in white areas produces shades. The blackness of the dots is always the same;they appear darker or lighter depending on how closely grouped. For example, if the user selects 100dpi as the desired shading, but the particles are too large, the toner will not stay within theboundaries of the dot size. This results in an overflow past the boundaries, filling in more of the area.Consequently, this produces a shade darker than desired by the user. This is how large sized tonerparticles limit the shading spectrum of high-resolution printers. The production of smaller, micro fineparticles create new challenges. The smaller particles will have different charge and flowcharacteristics that must be handled properly.



Paper

Paper isn't a consumable part of office machines, but as copiers, printers, and fax machines all haveto handle paper in various ways, paper is an integral part of their operating processes. In this sectionwe will take a look at the properties of paper that effect the operation of our machines.

Except where stated otherwise, we will use the term copier paper to include paper for plain paperfaxes and office printers.

SummaryProperties important in copier papers include weight, size, stiffness, smoothness, electrical resistivity,porosity, coefficient of friction, and moisture content. Some properties are important to copy qualityothers affect paper handling reliability. Image density and fusing are improved on smoother papers.Paper handling reliability and less background toning are obtained with rougher papers. Increasingresistivity improves density but also increases the tendency toward static, background toning, andfeathering.



Paper WeightThere are three commonly used systems for classifying paper weight. They are summarized in thefollowing table. Papers with weights at the extreme low and extreme high levels of a machine'sspecified tolerance range will tend to jam more frequently.

System Paper weight definition Where it is used

International(ISO) system

The weight in grams of a single one squaremeter sheet of paper. The units are gramsper square meter (g/m2)

Most of the world

US (lb) system The weight of 500 17" x 22" sheets ofpaper. The units are pounds (lb).*

USA

Japan (kg)system

The weight in kilograms of 1000 788 mm x1091 mm sheets of paper. The units arekilograms (Kg).

Japan

*This applies to Bond paper only. See the discussion of US paper weights below.Since the paper weights are defined differently, you cannot convert directly between them. Theconversion factors are as follows:

lb " g/m2 x 3.760 g/m2 " Kg x 0.860 Kg " g/m2 x 1.163

lb " Kg x 3.233 g/m2 " lb x 0.266 Kg " lb x 0.309



Paper Weights in the United States

In the United States, paper weight specification is a real dog's dinner. Weight depends onclassification. Sheets of paper that are actually exactly the same can have different weightspecifications if they are from the different classes.

The problem is that paper weight is measured by weighing 500 full sheets of paper. This is referredto as the "standard ream weight". So far so good, but now the fun begins. The size of a full sheet ofpaper is different for different types of paper! Some commonly used paper types are bond paper,book paper, card stock (or index stock), and cover stock. Lets take for example bond paper and bookpaper. A full sheet of bond paper is 17 x 22 inches. (A full sheet of bond is the equivalent of foursheets of 8½ x 11 inch paper.) A full sheet of book paper is 25 x 38 inches. So if you took 500 fullsheets of book paper that was the equivalent of 20 lb Bond paper, it would weigh more. Standard 20lb bond paper is actually the same as 50 lb book paper.

For copiers, paper specifications are written in bond weights. So, if a machine can copy on 14 to 42lb bond paper, it will accept from 40 to 100 lb book paper.

Confusing isn't it?



Paper Sizes

International Paper Sizes (ISO)

The ISO (International Organization for Standardization) paper sizes, which were based on theearlier DIN (Deutsche Industrie Norm) sizes, are commonly used everywhere in the world exceptCanada and the United States. The following table lists the sizes that can commonly be expected tobe used in copiers.

ISO A Series ISO B Series ISO C Series

A0 841 x 1187 B0 1000 x 1414 C0 917 x 1297

A1 594 x 841 B1 707 x 1000 C1 648 x 917

A2 420 x 594 B2 500 x 707 C2 458 x 648

A3 297 x 420 B3 353 x 500 C3 324 x 458

A4 210 x 297 B4 250 x 353 C4 229 x 324

A5 148 x 210 B5 176 x 250 C5 162 x 229

A6 105 x 148 B6 125 x 176 C6 114 x 162

A7 74 x 105 B7 88 x 125 C6 81 x 114

Sizes are in millimeters

Multiplying the 0 sizes creates large format sizes. For example, 2A0 = 1189 x 1682 and4A0 = 1682 x 2378

For More InformationFor a detailed discussion of theconcepts behind ISO paper sizesrefer to Markus Kuhn's web pageon international standard papersizes.(http://www.cl.cam.ac.uk/~mgk25/iso-paper.html)**As we have no control over this web page, Thecontent or location may change at any time.



Paper Sizes in the USA

Many paper sizes are in use in the UnitedStates. Copy paper sizes are defined ininches; the most commonly used sizes alsohave a name (letter, ledger, etc.). US papersizes are also used in Canada; however,there they are usually defined in millimeters.The table to the right gives the copier papersizes most commonly used in the USA.

Size in Inches Size in mm Common Name

4¼ x 5½ 108 x 140

5½ x 8½ 140 x 216 Statement

8 x 10½ 203 x 267 Government letter

8 x 13 203 x 330 Government legal

8½ x 11 216 x 279 Letter

8½ x 14 216 x 356 Legal

11 x 14 280 x 356 Computer

11 x 17 279 x 432 Ledger

17 x 22 432 x 559

22 x 34 559 x 864

34 x 44 864 x 1118



Japan JIS B Sizes

Japan has developed its own standards for papersizes. While the JIS (Japan Industrial Standard) Aseries of sizes is identical to the ISO A series ofsizes, the JIS B series is not. Also, Japan has noseries of envelope sizes comparable to the ISO Cseries.

JIS B Series

B0 1030 x 1456

B1 728 x 1030

B2 515 x 728

B3 364 x 515

B4 257 x 364

B5 182 x 257

B6 128 x 182

B7 91 x 128



Paper CharacteristicsThe following table summarizes the most important paper characteristics (other than weight andsize).

Brightness The brightness of a paper is a measure of its light reflectivity. A high grade paperusually has a brightness in the 85 ~ 90% range. Low grades would be in the 70 ~75% range. A high grade looks bright (white) and a low grade dull (gray). This is ameasurement of the incident light that is reflected from the paper's surface.

Coefficient offriction

The coefficient of friction directly affects the efficiency of paper feeding. It must behigh enough that the feed and transport rollers can get a good grip. However, it mustbe low enough that the sheets of paper slip over each other. Also, the coefficient offriction should not vary from sheet to sheet as variations in friction could causemulti-feeds and jams.

Curl Curl in paper is a major cause of transport problems resulting in misfeeds. Basically,copier paper should be manufactured to remain as nearly flat as possible while It issubjected to varied temperatures and humidity changes as it proceeds through thecopy making process.Paper in a copier's paper tray tends to curl as it picks up moisture from the air. Somemachines, especially higher speed models, have heaters in the paper trays toprevent such curling.

ElectricalResistivity

If paper resistivity is too high it can cause static build-up that results in doublefeeding and jams. Too low an electrical resistivity (= higher conductivity) can causeimage deletion (blank areas) as well as jams. Resistivity is affected by moisture andpaper composition.



Moisturecontent

Moisture content directly affects paper transport, copy quality, and curl. Thegenerally acceptable range is 4 ~ 6 percent moisture. A higher moisture content willcause curl, a higher jam rate, poor image transfer (due to lower resistivity), andpoorer image fusing. A lower moisture content causes static that results in misfeedsand double sheet feeding.

Opacity Paper must be sufficiently opaque to prevent image show through. This is especiallyimportant in paper used for duplexing. Most brands of paper use some kind of fillerto enhance opacity. The composition of the filler can affect copier performance anddurability of parts. Some common fillers are clay, chalk, and marble.

Porosity Mottling and smearing can result from excess porosity. Low porosity paper tends tohave more curl and is prone to image smearing.

Shade Shade will vary from a pure white to tints in the blue, pink, or yellow ranges. Shade isa personal preference but also may vary between lots of paper or within a brand.Close control of shade is most important for papers used in color printing andcopying.

Smoothness Smoother papers increase electrostatic adhesion at the image transfer step. This isbecause closer contact with the photoconductor makes the paper more difficult tostrip from the photoconductor. Smoother papers are also more likely to havebackground toning. Too rough a paper may cause image mottling, poor imagefusing, and high toner consumption.



Stiffness Paper stiffness is classified by cross grain and with grain. Thestiffness is a result of the orientation of the fibers within thepaper. In most copier papers, the fibers are orientated in thelength direction of the paperStiffness affects paper feeding and transport in copiers andlaser printers. Paper is generally two or three times stiffer in thewith grain direction than in the cross grain direction.

Surfacecondition

Paper finishing and surface properties have an impact on long-tern satisfactoryperformance of copier equipment. Copier papers should be tightly controlled toeliminate such problems as:• Dirt and dust—which can cause reduced machine reliability, misfeeds, and copy

quality defects.• Surface inclusions—which can result in poor copy quality, sheet weakness, and

transport problems.• Torn and wrinkled sheets—which can cause poor transport, misfeeds, and

machine damage.Thickness Paper thickness is measured in micrometers. Typical copy paper has a thickness of

about 95 micrometers. For copy paper, thickness is a direct function of paper weight;so, for our products, generally only paper weight is specified.



The following table gives Ricoh Standards (= ideal paper) for some selected paper characteristics.(Not all possible paper characteristics are included.)

StandardItem Units

B/W Color

Weight g/m2 69.5 ±4.0 80.0 ±4.0

Thickness µm 92 ±6 95 ±6

Stiffness — With grain: ≥55Cross grain: ≥28

With grain: ≥55Cross grain: ≥28

Brightness % ≥80 ≥82

Smoothness S Front: 60 ±20Back: 50 ±20

120 +40/-35(front and back)

Ash content % 1 ~ 5 —

Moisture % 4.0 ~ 6.0 4.0 ~ 6.0

Resistivity ΩΩΩΩ∙cm 8 x 109

~2 x 10118 x 109

~6 x 1010


AAppppeennddiixx 11

Glossary of Terms

Agitator A type of mechanical mixing device; used in copiers in the toner supply to keep tonerparticles separated; also used in the development unit to combine toner and carrier,creating two—component developer.

AI Short Protocol Artificial Intelligence Short Protocol reduces the time required for the protocolexchange with a particular terminal by saving the communication parameters and themodem rate used to send the last page of a transmission. These parameters are usedfor the start of the next transmission to that terminal.

Air Knife (or AirSeparation)

The air knife paper separation process uses jets of air to separate sheets of paper forpaper feed.

Attenuation After the modem converts data to serial and modulates it, the data passes through anattenuator, which adjusts the TX level.

Auger A screw-like mechanical transport device used to move bulk materials in manydifferent applications. It relies on a large screw with deep, wide-pitched threads turninginside a close-fitting cylinder. The threads act like an endless scoop or wedge to liftmaterial from one end of the cylinder to the other.

Automatic DocumentFeeder (ADF)

A motorized device that allows automatic feeding, alignment and stacking of multipleoriginals, greatly improving the overall efficiency of photocopying.


Appendix 1 Glossary of Terms

Automatic DocumentHandler (ADH)

An advanced type of document feeder that can recycle and reverse originals.

Autorouting When a G3 fax message with a SUB code is received, the machine compares it withthe personal codes stored in the machine with e-mail addresses. If there is a match,the machine automatically routes the message to that e-mail address.

Baud Rate The Baud Rate is the number of bits per second divided by the number of bits perBaud.

Bias Roller A bias roller is a roller that has a constant electric voltage applied to it. Such rollers areused at various places in copiers and printers. A typical use is in a copier’s cleaningsystem, where a bias roller is often used to attract toner removed by a cleaning bladeor brush.

Bipolar JunctionTransistor

A bipolar junction transistor contains two junctions between p and n typesemiconductor, and three electrodes (the collector, the base, and the emitter). SeeTransistors.

Block Diagram A kind of electronic map that divides a system into a number of functional “blocks”; itshows all the interconnections among the blocks, but generally does not show detailinside them.

Bond A category of papers, consisting of many individual types. Most bond papers aresuitable for use in plain-paper copiers.

Breakdown Voltage The voltage at which current will flow in reverse through a diode. Regular diodes willgenerally be destroyed if a reverse voltage greater than the breakdown voltage isapplied; however, zener diodes are designed to operate at the breakdown voltage.See Zener Diode.



Brushless DC Motor In standard DC motors, the magnet is stationary while the coil rotates, and brushescomplete the electrical contact to the rotor. However, In a brushless DC motor, the coilis stationary and the magnet moves.

Call CollisionPrevention

After the scanning the document, the machine checks whether there is an incomingfax message. The machine cannot dial if there is an incoming message. This differsbetween North American, and European and Asian models. See North Americanmodels and European and Asian models.

Carrier (copiers) Carrier is one of the components of a two-component developer. Carrier consists oftiny iron-based beads that attract toner particles through a triboelectric charge andtransport them to the photoconductor during the development process. SeeTriboelectric Charge.

Carrier (facsimile) The carrier is the base frequency wave that fax machines use for communication. Totransmit data, fax machines superimpose a modulating signal onto the carrier wave byvarying the frequency, amplitude, or phase (or a combination of these) in a standardmanner. See Modulation Techniques.

Central Processing Unit(CPU)

A microprocessor chip that is used as the primary control and information processingdevice in a sophisticated electronic system.

Charge The first step in the copy process; during the charge process, an even electricalcharge is applied to the photoconductor, preparing it to receive the image of an originalduring exposure.

Charge Corona Unit A corona unit used for the first step in the copy process, to apply an even high—voltage charge to the photoconductor; usually ventilated by a blower to help distributeions during charging.



Charge CoupledDevice (CCD)

A solid-state component made from a number of very small light-sensitive elements;the amount of light falling on each element produces an electrical signal ofcorresponding strength. CCDs are used in laser-based copiers, fax machines andsome television cameras.

Cleaning That step in the copy process during which residual toner particles—those left behindafter image transfer—are removed from the photoconductor. Cleaning relies mainly onmechanical systems but electrostatic forces may also be used.

Cleaning Blade An element in a copier’s cleaning system. After a copy has been made, the cleaningblade acts like a windshield wiper, riding along the surface of the photoconductor towipe off all remaining toner particles.

Cleaning Brush An element in a copier’s cleaning system. After a copy has been made, the cleaningbrush removes the residual toner from the surface of the photoconductor. See BiasRoller.

Clutch A control device for rotational movement; a clutch will either be engaged, locking itscomponents together and transferring rotation, or disengaged, letting its componentsturn separately and preventing the transfer of rotation.

Clutch, Magnetic See Magnetic Clutch.

Clutch, MagneticSpring

See Magnetic Spring Clutch

Clutch, Slip See Torque Limiter Clutches. See Slip Clutch.

Clutch, Spring See Spring Clutch.

Clutch, Torque Limiter See Torque Limiter Clutches.



Coefficient of Friction(of paper)

The coefficient of friction directly affects the efficiency of paper feeding. It must be highenough that the feed and transport rollers can get a good grip. However, it must be lowenough that the sheets of paper slip over each other.

Cold CathodeFluorescent Lamp

A variation of the fluorescent lamp. See Fluorescent Lamps, Applications.

Contact Image Sensor

(CIS)

The contact image sensor (CIS) is a compact image reading assembly containing anLED array, an array of self-focusing optic fibers (SELFOC), and a strip of lightdetectors, such as phototransistors. The CIS is used instead of the CCD in the mostcompact of fax machines.

Corona Unit A copier component that uses a high electrical voltage to create a localized electricalfield of charged ions; various kinds of corona units are used at different points in thecopy process. See Pre-Cleaning, Quenching, Transfer And Separation Corona Units.

Corona Wire A thin wire usually made from tungsten and coated with carbon. Mounted inside acorona unit, it carries the high voltage needed to generate an electrical field for aspecific copier application.

Cross Mixing The process by which toner and carrier are mixed together inside a copier; alsocreates and distributes the triboelectric charge that binds the toner to the carrierparticles.

Current The rate of flow of electricity through a conductor; current is measured in Amperes orAmps.

Data Compressor andReconstructor - DCR

Part of a fax circuit; it compresses the data before sending it out over the telephoneline. It also reconstructs compressed data coming in from the telephone line.

DC Motor A motor that operates on direct current.



DC motor, Brushless See Brushless DC motor.

Developer,Mono-component

See Mono-component Developer.

Developer,Two-component

Also called dual-component developer. See Two-component Developer.

Development That step in the copy process which first produces a visible image on thephotoconductor. During development, toner is applied to the photoconductor, where itis electrically attracted to the latent image formed during exposure.

Development Roller Part of a copier’s development system. Development rollers use some combination ofmagnetism, triboelectric charge and/or bias voltage to apply toner to the latent imageon the photoconductor.

Diode A p-type semiconductor joined to an n-type semiconductor. A diode allows current tomove in only one direction. See Diodes.

Diode, Zener See Zener Diode.

DNS Domain Name System is a service that enables the IP address to be obtained from thehost under the TCP/IP network environment.

Doctor Blade Part of a copier’s development system. It limits the thickness of developer picked upby the development roller by scraping off the excess as the roller turns. It determinesthe height of the magnetic brush.

Dual Component Toner Toner designed to work in a dual-component development system. This toner issimilar to the non-magnetic type monocomponent toner. It works with a separateparticle known as a carrier. The mixture of toner and carrier is known as developer.



Duplex Unit A paper handling device that permits the making of two-sided copies without manualintervention by the user. Available through the installation of a peripheral duplex uniton mid-size copiers, duplexing is a standard feature on most high-volume machines.

Duplexing Making two-sided copies.

ECM Memory Error Correction Mode memory, an optional extension to Group 3 protocol, is acountermeasure for the frequent data errors that occur in areas that suffer from noisytelephone lines. See ECM.

Electromagnetic Clutch A type of clutch which contains its own electromagnetic actuator. When the clutch’scoil is energized, two metal plates are pulled together and transmit rotation to a givencomponent. When not energized, the two plates are separated by a spring, and norotation is transmitted.

E-mail Electronic mail is a system in which messages in the form of digital data are sent andreceived between computers.

Erase Lamp A component which removes certain parts of the latent image after exposure. Afterconsidering reproduction ratio and paper size, the main control board turns on specificsections of the erase lamp to remove the charge from the photoconductor outside thedesired image area.

Estimated FillbitControl-EFC

This process was developed by Ricoh to improve the efficiency of MH, MR, and MMRcoding.

Ethernet This is the most commonly used LAN. See Ethernet Frame Structure.

Exposure A process where light is applied to a photoconductor to create a latent reverse imagein the form of a charge pattern on the surface of the photoconductive material. SeePhotocopying Processes.



Exposure Lamp Part of a copier’s exposure and optical systems; provides the necessary illumination tocreate a reflected image from an original, which in turn creates an electrical latentimage on the photoconductor.

Fax On Demand-FOD A polling application with pre-recorded voice assistance.

FRR Paper Feed One of the standard paper feeding systems; the FRR (feed and reverse roller) feedmechanism consists of a pick-up roller, a feed roller, and a reverse roller.

Feed Roller The first roller to handle paper a copier’s paper feed system; pulls individual sheetsfrom a paper supply, feeding them into the copier where they are passed to otherrollers in the paper path.

FIFO Memory First-In First-Out Memory synchronizes the transfer of video data to (transmission) orfrom (reception) the modem.

Fluorescent Lamp A lamp consisting of a gas-filled, closed glass tube that has electrodes at each endand an internal coated surface of a phosphorous material.

Frequency Shift Keying Frequency shift keying (FSK) is s type of frequency modulation that is used fortransmitting digital signals.

Fusing The step in the copy process that bonds toner to a sheet of paper. Heat and pressuremelt toner and force it into the paper surface, creating a copy that meets or exceedsthe durability of the original.

Fusing LubricationSystem

Part of a copier’s fusing system, needed to keep toner from sticking to the fusingrollers. Uses an absorbent pad and/or a blade to coat the rollers with silicone oil.

Gray Scale A row of small test patches showing a full range of image density, from solid black topaper white, usually in five to ten steps. Printed on a copier test chart. It is a gauge forthe side-to-side and overall image density of the machine.



Grid Plate Part of the charging system in copiers that use an Organic Photoconductor (OPC).OPCs are more sensitive to high voltage charges, so the grid plate acts as a regulatorbetween the OPC surface and the charge corona.

Hall Effect Sensors Hall effect sensors are used in some network control units (NCU) of fax machines todetect line current.

Halogen Lamp An incandescent lamp filled with halogen gas.

Hot Roller The part of a copier’s fusing system that contains the fusing heat source, usually ahalogen lamp. The hot roller is usually coated with Teflon, and works with the pressureroller. See Pressure Roller.

I/O Rate In fax machines this refers to the amount of time necessary for the scanner or printerto process one scan line of image data. Modulation and demodulation are not includedin this time measurement.

ID Sensor A photosensor that measures the image density (reflectivity) of the drum and of a testpattern (ID sensor pattern). The output of this sensor is used to control toner supply.

ID Sensor Pattern A standard pattern that is exposed and developed for sensing by the ID sensor.

Image Density The quality of an original or copy that describes its relative lightness or darkness; highimage density refers to a very dark copy, low image density refers to a very light copy

Image Density Control The system in a copier that compensates for the variation in reflectivity amongdifferent originals. Some adjust the brightness of the exposure lamp. Others regulatetoner transfer during development, by adjusting a bias circuit. In either case, imagedensity controls can be manual, automatic or both.



Interleave Duplexing A duplexing method used by some digital machines that speeds up duplexing bystoring original images in memory. Sheets continually feed and reverse withoutstopping and the correct image for each sheet and side is selected from memory.

ITU-T Standards International standards for data communication.

JBIG Compression The JBIG compression method consists of four processes: conversion to bi-level data,progressive coding, division into strips, and coding.

LAN Local Area Network. See LAN Fax, LAN Basics.

Large Capacity PaperTray

A copier peripheral that holds a much greater amount of paper than a standard tray,thereby enabling the copier to run for longer periods without the supply being refilled,typically holds between 500 and 3000 sheets.

Laser Diode An LED that outputs laser light.

Latent Image A photographic term which refers to an undeveloped image on a piece of film; inxerography, it refers to the invisible, electrostatic image formed on the photoconductorduring exposure.

LCD LCD is an abbreviation for Liquid Crystal Display. An LCD is a digital display thatconsists of two sheets of glass separated by hermetically sealed liquid crystal material.The liquid crystal is normally transparent.

LCT See Large Capacity Tray.

Lead Edge The first paper edge to contact the latent image on the photoconductor. The “frontedge” of a copy as it travels through the paper path.



Lead Edge Erase The removal of that portion of a latent image which corresponds to a narrow stripalong the lead edge of the copy, usually no more than 5 mm wide. This prevents adark line from the edge of the original document from appearing on the copy. Achievedthrough the action of an erase lamp immediately after the exposure process.

Light Emitting Diode A kind of diode that emits photons. Usually shortened to “LED”.

LED Array LEDs mounted together in an array as a light source.

Line Buffer A memory buffer that ensures synchronization of video data transfer between differentcomponents of the circuit.

Magnetic Brush A localized concentration of two-component developer formed on the surface of adevelopment roller by magnetic fields. It brushes developer over the photoconductorduring the development process. This allows toner particles in the brush to beattracted to the latent image.

Magnetic Clutch See Electromagnetic Clutch.

MagneticMonocomponent Toner

Similar to the non-magnetic monocomponent toner, this type has iron oxide particlesencapsulated in the resin matrix of each individual particle of toner. The toner isn’tactually magnetic itself, but it can be attracted by a magnet.

Magnetic Spring Clutch The magnetic spring clutch is a hybrid of the electromagnetic and spring clutches.Unlike the normal spring clutch, the spring is loose when idling.

Magnification Lines Two lines of an identical specified length, one vertical and one horizontal, printed on acopier test chart. Used to check the vertical and horizontal magnification of a copier’soptical system.



Main Control Board A printed circuit board containing the most important components in a copier’selectronic control system, including the Central Processing Unit (CPU), and factory-programmed instructions stored on Read Only Memory (ROM) chips. The main boardis linked to other parts of the control system with a number of multi-wire connectors.

Master Belt A wide, flexible loop of plastic with an organic photoconductor surface.

Modified HuffmanCompression

This compression method has one-dimensional coding scheme codes scan line datawithout reference to data on adjacent lines.

Microswitch Microswitches are electromechanical switching devices containing two contacts.

MIME Multipurpose Internet Mail Extensions is a specification for the inclusion of varioustypes of data in e-mail.

Modified MRCompression

The Modified MR method uses the same algorithm as the MR method, but has 6 maindifferences.

Modulating Signal The data signal from the fax machine. See Modulation Techniques.

Moisture Content(of paper)

Moisture content directly affects paper transport, copy quality, and curl. The generallyacceptable range is 4 ~ 6 percent moisture. See Paper Characteristics.

Monocomponent Toner A special toner formulation that has both magnetic and electrical properties; functionswithout carrier. See Monocomponent Developer.

Motor, Stepper See Stepper Motor.

Moving Platen A type of scanning optical system in which originals are placed on a glass documentsurface (the platen) which moves across a fixed exposure slit and lamp during anexposure; found only on relatively small, low-speed copiers.



Moving Scanner A type of scanning optical system in which originals are placed on a fixed glassdocument surface, under which is a moving lamp and mirror assembly (the scanner).This scanner moves under the original during an exposure. Found on most medium-to-high speed copiers; this design is also known as “fixed platen” scanning

Modified ReadCompression

This is the Modified Read compression method. It is an expanded form of the one-dimensional run length encoding method. While the MH method encodes pixels in thepixel scanning direction, the MR also takes notice of the pixels in the feed direction.

Neon Lamp Similar to the cold cathode fluorescent lamp, but light emission is from the neon gasrather than the phosphorous inside coating.

Network Control Unit(NCU)

Interfaces a fax machine with the telephone network.

Network InterfaceCircuits

The filters, relays, attenuators and other components in these circuits interface themachine with the public telephone network.

New Estimated FillbitControl

Fill bits are never added to the data and the receiver uses the SAF memory or harddisk instead of the FIFO memory. If the receiver's memory is full, it sends PIN to thetransmitter and the line is disconnected.

Non-magneticMonocomponent Toner

All-in-One toner that contains pigments for printing in a matrix of resin. This kind oftoner usually comes in a cartridge and is used with non-magnetic rollers.

Offset Image A partial image that remains on the photoconductor or fusing rollers due to incompletecleaning and is transferred to subsequent copies.

Opacity of Paper Paper must be sufficiently opaque to prevent image show through. This is especiallyimportant in paper used for duplexing. Most brands of paper use some kind of filler toenhance opacity. See Paper Characteristics.



OrganicPhotoconductor (OPC)

A type of photoconductor based on certain organic chemicals, rather than metallicelements like selenium or silicon. An OPC requires negative charging beforeexposure. It is generally non-toxic, enabling it to be handled and disposed of moreeasily than selenium types.

Over-toning A condition that occurs when a copier’s toner supply system is delivering too muchtoner to the development unit; the excess toner builds up inside the copier, especiallyaround the photoconductor and paper path.

Paddle Roller Part of the development unit of many copiers. It pushes charged developer (a mix oftoner and carrier) against the development roller, which picks up the developerthrough magnetic attraction and brushes it over the latent image.

Paper Brightness The brightness of a paper is a measure of its light reflectivity. See PaperCharacteristics.

Paper Curl Curl in paper is a major cause of transport problems resulting in misfeeds. See PaperCharacteristics.

Paper Feed System The various rollers, belts, sensors and control devices that are responsible for movingsheets of paper through the copier; begins with the paper supply, and ends with theexit tray or sorter that holds the finished copies. See Paper Feed

Paper Size There are several standard systems for measuring paper size. The most commonlyused is the ISO (International Organization for Standardization) series of paper sizes.In the United States, paper sizes are usually measured in inches.

Paper Stiffness Paper stiffness is a result of the orientation of the fibers within the paper. Stiffnessaffects paper feeding and transport in copiers and laser printers. Paper is generallytwo or three times stiffer in the with grain direction than in the cross grain direction.See Paper Characteristics.



Paper Weight There are three systems for classifying paper weight. These are the ISO system(g/m2), the USA system (lb), and the Japanese system (Kg).

Parallel Circuit A type of electrical connection in which components each have a direct, independentpath to a power source.

Phosphor A chemical coating on the inside of a fluorescent tube that produces visible light whenstruck by ultraviolet radiation. See Fluorescent Lamp.

Photoconductor A special material that acts as an insulator in darkness and as a conductor whenexposed to light.

Photointerrupter An electronic sensors that has a photocell and a light emitting diode (LED) on eitherside of a small gap. When a tab on a moving component enters the gap, it blocks thelight from the LED, shutting off the photocell and signaling the component’s position tothe machine’s Main Control Board.

Phototransistor A phototransistor works like an ordinary bipolar transistor, except that light shining onthe base of the transistor switches it on.

Pick-off Pawls Part of a copier’s paper separation system that provides a mechanical separationmethod. Pick-off pawls ride along the surface of the photoconductor to peel off anypaper not removed electrically.

Point-to-point Diagram An electronic map, specially designed for troubleshooting equipment with replaceablecircuit boards; combines features of a schematic drawing and a block diagram,concentrating on connections to and from different components.



Polarity The quality of electricity that describes its tendency to exist in either a positive ornegative state. In most electrical circuits, polarity determines the direction of currentflow. In electrostatic charges, polarity indicates the charge of ions that make up anelectrical field, and therefore determines the polarity of materials that can be attractedby that field. A charge of a given polarity always attracts materials with a charge of theopposite polarity

Polyphase Shift Keying A type of phase modulation (PM) where data modulation occurs by altering the phaseof the carrier wave and frequency remains constant.

POP Post Office Protocol servers are computers that receive mail using SMTP. The mailincludes a setting to ensure that it is directed to the POP server. POP servers are usedwhen the user is not permanently connected to the internet.

Pre-cleaning CoronaUnit

A corona unit used just before cleaning in the copy cycle. It creates an electrical fieldthat reduces the charge on the photoconductor before mechanical cleaning, making iteasier to remove leftover toner.

Pressure Roller Part of a copier’s fusing system. During fusing, toner is forced into the surface of thepaper by two rollers, the pressure roller and the hot roller. The pressure roller isusually made of silicon rubber, to help it withstand heat and provide a good grip on thepaper. See Hot Roller.

Pre-transfer Lamp Used in some copiers to reduce the charge of the latent image after development,weakening its attraction just enough to assure a clean transfer. It also prevents tonerparticles from being attracted back to the photoconductor during separation.

Process Control Process control is a system that automatically changes machine processes tocompensate for changes in the environment or the machine condition.



Protocol Signals Fax machines use two types of signals: Single (short, timed transmitted tones likeCED and CNG) and frame-like HDLC signals that transmit digital information like DISand NSF.

PSTN Public Switched Telephone Network

Quadrature AmplitudeModulation (QAM)

QAM is a combination of amplitude modulation (AM) and phase modulation (PM).

Quenching Quenching is the process that eliminates any residual electric charge remaining on thephotoconductor after the cleaning process. Quenching prepares the photoconductorfor the charge step of the next copy or print cycle.

Quenching Corona A corona used at the end of the copy process; it creates an electrical field to helpremove latent image charge on the photoconductor after mechanical cleaning,preparing the surface for the next copy cycle; always used in conjunction with aquenching lamp

Quenching Lamp Shines light on the surface of the photoconductor to remove the latent image, after theleftover toner has been removed by the cleaning system. See Quenching.

Reception Modes There are two types of reception modes: manual (telephone mode) and automatic (faxmode).

Reed Switch Reed switches are magnetically operated switches with contacts hermetically sealed ina glass capsule.

Reflective Photosensor Reflective photosensors are short-range sensors that have a light emitting element(usually an LED) and a light sensitive element (usually a phototransistor).



Registration The process by which paper is lined up properly with the developed image on thephotoconductor; registration is usually accomplished with a system of rollers,mechanical guides and electronic sensors.

Registration Marks These marks are printed at the top and side of a copier test chart as a gauge of paperalignment and copier erase margins. They consist of thin parallel lines that will show ifthe paper is improperly meeting the latent image on the photoconductor.

Registration Rollers Part of a copier’s paper feed system. A pair of rollers that align a sheet of paper toremove skew, and then feed the sheet toward the photoconductor at the correct timeduring the copy cycle to align it with the image on the photoconductor.

Registration Sensor Part of a copier’s paper feed system; an electronic sensor mounted in the paper pathjust before the registration rollers. This sensor alerts the copier’s control system whena sheet of paper approaches the registration rollers, so that they can be stoppedbefore the sheet contacts them.

Relay Devices Required to expand LANs. These devices do the following: extend the connectiondistance, enable connection between networks of different standards, allow control ofhigh-speed transmission routes and filtering. They include repeaters, bridges,switches, gateways and routers.

Relay Rollers Part of a copier’s paper feed system; used in machines with long or complex paperpaths simply to move sheets from one area to another. They have no special copy-related function.

Reproduction Ratio An optical specification that determines the relationship between original size and copyimage size. A one-to-one reproduction ratio indicates that the original and copy havethe same image size. This ratio can vary in most copiers to produce enlarged andreduced copies.



Resolution Bars Printed on a copier test chart as a gauge of the overall sharpness of a machine’soptical system; should be clearly visible on copies as individual lines.

SAF Memory Store and Forward Memory stores fax messages to send later or for transmission tomore than one location. It also holds the incoming message if, for example, the printeris out of paper.

Scanner Part of the exposure system in a moving-scanner copier; these exposure systemshave two scanners. The first consists of a lightweight metal frame containing onemirror and the exposure lamp. The second has a similar frame and two mirrors. Bothscanners move along guide rails during an exposure, and reflect the image betweenthem during the scan to maintain a constant optical distance from the original to thelens.

Schematic Diagram The most traditional and detailed type of electronic map; shows every circuit, no matterhow complex, and every component, no matter how small.

Selenium Drum A commonly used photoconductor. It consists of a hollow aluminum cylinder coatedwith a layer of selenium-tellurium or selenium-arsenic alloy. The selenium alloy layerprovides the key photoconductive property of having high electrical resistance in thedark, and low resistance when exposed to light.

SELFOC An acronym for Self-Focusing Fiber Optic Array. SELFOCs are used for strip exposurewith fixed optics, in contact image sensors, and direct scanning digital systems.

SEP/PWD/SUB/SIDSignals

The ITU-T recommendations were changed in 1996 to allow polling and confidentialcommunications. At this time, this could only be done between Ricoh-made products.With the institution of these signals, communication between all fax makers becamepossible.

Separation That step in the copy process during which the paper and toner are separated fromthe photoconductor. See Image Transfer And Paper Separation



Servomotor Used in many copiers to move scanners in the optical system; servomotors emit aspecific number of electrical pulses with each revolution, allowing a control circuit tomonitor and regulate their speed. Servomotors use feedback to maintain a constantrotating speed.

Setting Powder A dry lubricant powder applied to new photoconductors and or cleaning bladesimmediately before installation. During initial operation, the powder protects thesurface from scratches that might result from contact with other copier components.

Slip Clutch Another name for a torque limiter clutch. See Torque Limiter Clutch.

SMR Compression The Simple Modified Read method is identical to MR coding except that the Kparameter is 8 for Standard and Detail resolution and 16 for Fine.

SMTP Simple Mail Transfer Protocol is the protocol for communication between internet mailMTAs (message transfer agents).

Solenoid A simple electrical control device, consisting of a hollow electromagnet and a metalplunger. When the magnet is energized, the metal plunger is pulled inside it, triggeringwhatever mechanism is attached.

Sorter A sorter is a paper handling device that feeds finished copies into multiple output bins;can produce sets of collated copies, matching the order of the original documents, orcount out stacks of single copies.

Spring Clutch A popular clutch for copier applications; its internal components are normally heldtogether by a spring connected to an external sleeve, and rotation is transmitted to agiven component. When the sleeve is kept from turning, the spring expands, releasingone internal component and preventing the transfer of rotation.

Super Speed Coding(SSC) Method

The Super Speed Coding method combines EFC with Short Preamble and white linedouble-speed processing to achieve a further reduction in transmission time.



Stator A stationary part of an electric motor in or about which a rotor turns. See DC Motors.

Stepper Motor A type of electric motor designed to be controlled in individual steps that are portionsof a full rotation, each step as small as one degree of arc. It is often used to adjustlens position in copiers with variable reproduction ratio. The design of a stepper motorallows for extremely precise lens placement and easy electronic control. Steppermotors are used whenever accurate positioning of a component is required.

Stripper Pawls Part of a copier’s fusing system; stripper pawls ride along the surface of the hot roller,and peel off copies that stick to the roller despite the roller’s lubrication.

Subnet It is difficult for one network to handle 65,534 hosts, therefore the subnet mask createssubnets to take some of the burden off of the main network. See Subnet and SubnetMasks.

Subnet Mask Subnet masks divides the host block into a maximum of 255 subnets within which amaximum of 255 hosts can exist. This helps to increase the speed with which a usercan access a particular portion of the network. See Subnet and Subnet Masks.

Substitute Reception Data is stored in memory as it comes in to avoid loss of data if there is a printerproblem. Basically, this means that memory substitutes for the print engine duringreception.

TCP/IP (TransmissionControl Protocol/Internet Protocol)

A standard internet protocol supported by Windows 95, it allocates 32-bit networkaddresses to nodes. The host requires a procedure for passing IP packets to thedesired application. This procedure is filled by the TCP/IP.

Test chart A specially designed copier original, with printed gauges used to assess many aspectsof copy quality.



Thermal Head The thermal head is the central component of the thermal printer. A thermal headconsists of a row of heating elements. If a heating element is turned on, it will heat up.The heat from the element will make a dot on thermosensitive printer paper.

Thermal Paper Thermosensitive printer paper. This is the paper used for white-board printers andthermal fax machines.

Thermistor A thermistor is a thermally sensitive resistor. It is a heat-sensitive electroniccomponent, which indicates changes in temperature by varying its electricalresistance.

Thermoswitch An electrical control device used for overheat protection in office machines.

Toner The “ink” of an electrostatic copier that forms the actual image on finished copies. It ismade from resin and a solid lubricant combined with carbon or a colored pigment. Indual-component development systems it is bound to carrier particles by a triboelectriccharge, creating two-component developer. See Triboelectric Charge.

Toner Density Sensor(TD Sensor)

The toner density sensor (or TD sensor) measures the concentration of toner in thedeveloper.

Toner End Sensor Part of a copier’s development system. The toner end sensor monitors the level oftoner in the toner supply. When the sensor detects a predetermined “low-toner”condition, it signals the control system, which then lights a corresponding indicator onthe machine’s operation panel. It usually detects two different toner levels: “TonerNear End” (low) and “Toner End” (too low to continue operation).

Toner Overflow Sensor Part of a copier’s cleaning system. This sensor monitors the level of toner in the usedtoner storage tank. When the sensor detects a predetermined used toner tank fullcondition, it signals the control system, which then lights a corresponding indicator onthe operation panel of the machine.



Toner Shield Glass A piece of ordinary glass used in copiers as a “window” in the exposure slit; allowslight to reach the photoconductor, but keeps toner from contaminating the opticalsystem.

Toner Supply System A combination of electronic and mechanical components that monitor the density oftoner and add toner to the development unit whenever the density falls too low.

Toner, DualComponent

See Dual Component Toner.

Toner, Magneticmonocomponent

See Magnetic Monocomponent Toner.

Toner, Non-magneticmonocomponent

See Non-magnetic Monocomponent Toner.

Torque limiter clutch In concept, torque limiter clutches transmit rotation to a drive component (usually aroller, pulley, or gear mounted on a rotating shaft). As long as the resistance to rotationis less than the torque (twisting force) limitation of the clutch, the roller turns with theshaft. If the resistance exceeds the torque limitation, the roller stops turning. It slipsand in fact, may turn in the opposite direction if sufficient counter force is applied.

Transfer That step in the copy process in which toner, held by the latent image on thephotoconductor, is transferred to a blank sheet of paper, thereby creating a copy.



Transfer andSeparation (T/S)Corona Unit

A corona unit used immediately after development. The T/S corona unit creates twocoronas. The first, the transfer corona, is an electrical field that pulls the developedtoner image away from the latent image on the photoconductor, transferring it to asheet of paper. The second corona, the separation corona, is an electrical field thatreleases the paper, together with the developed toner image, from thephotoconductor.

Transport The primary job of a copier’s paper feed system: moving sheets of paper from thesupply, through the machine, and out into the exit tray; accomplished with a variety ofrubber belts and rollers.

Trapping Layer The surface layer of a photoconductor. It receives and traps an electrostatic charge onthe surface as long as the photoconductor is in darkness.

Tray Heater Paper in a copier's paper tray tends to curl as it picks up moisture from the air. Somemachines, especially higher speed models, have heaters in the paper trays to preventsuch curling.

Trellis Code Modulation(TCM)

TCM uses QAM, but part of the data signal is encoded, using trellis coding, for errorcorrection purposes.

Triboelectric Charge A type of static charge that builds up when certain materials are rubbed together.Triboelectric charges attract toner to carrier in a two-component developer system.

Two-componentDeveloper

The most popular developer formulation; uses tiny, metallic carrier beads to delivermuch smaller toner particles to the photoconductor during the development process.

Under-toning A condition that occurs when a copier’s toner supply system is delivering too little tonerto the development unit; can lead to carrier abrasion, which may damage thephotoconductor and shorten the useful life of the carrier particles.



V Sensor A reflective photosensor similar to the ID sensor that indirectly measures drumpotential. Used before the development of the potential sensor system, it can be foundin earlier models using process control.

Varistor Acts like two zener diodes connected back to back.

VB or VBB Development bias.

VD (Dark Potential) The drum potential in black image areas after exposure. Standard VD is the potentialmeasured after exposing a black pattern.

VD Pattern A standard black pattern used for reference.

VG or VGRID Charge corona grid potential.

VH (Halftone Potential) A standard halftone drum potential. This value is used for laser power adjustment inthe process control system of some digital products.

Video Processing The processing that is applied to image data after the machine scans the document.Both analog and digital video processing steps may be applied to the image data.

VL (Light Potential) The drum potential in white image areas after exposure. Standard VL is the potentialmeasured after exposing a white pattern.

VL Pattern A standard white pattern used for reference. On some machines the VL pattern isactually a light gray tone rather than pure white.

VLAMP Exposure lamp voltage.

VO (Original Potential) The drum potential after the drum is charged.




This converts recorded voice messages from analog (audio) to digital for storage inthe memory. It also retrieves the message from memory to send it out over thetelephone line.

VR (Residual Voltage) The drum potential after the drum has been exposed by the erase lamp.

VREF, VTREF A targeted control reference for the TD sensor. When VTD becomes too low, toner isadded to the developer to bring VTD back to the VREF value.

VSG The ID sensor output when checking the erased drum surface.

VSP The ID sensor output when checking the ID sensor pattern image.

VTD, VT, or VOUT The output voltage of the TD sensor.

Xenon Flash Lamp The xenon flash lamps used in office machines are basically the same as the flashlamps used in photography only much larger.

Xenon Lamp A xenon lamp is a xenon-filled glass tube with terminals at each end. When a voltageis applied across the lamp terminals, the xenon gas ionizes and current flows throughthe gas, which emits light. The terminals do not have to be preheated, unlike influorescent lamps. Fluorescent xenon lamps also utilize a phosphor coating on theinside wall of the lamp to generate light.

Xerography The indirect electrostatic copying system which is the basis of all modern plain papercopiers; patented in 1939 by Chester Carlson, Xerography comes from the Greekwords for “dry writing”.

Zener Diode A diode connected in reverse to a normal diode and is designed to work in excess ofthe breakdown voltage.


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