Principle of Magnetography
Magnetolithography was described as a method for setting up
computer to press/direct imaging systems with re-imageable
surfaces. This process is based on magnetography
The figure shows the printing unit of a magnetography-based
printing system.
A magnetizable drum serves as the image carrier; it consists of
a non-magnetic core, coated with a soft magnetic FeNi layer
(thickness around 50 m). On top of this there is an additional hard
magnetic Co-Ni-P layer (around 25 m thick) and then finally a
protective layer (around 1 m thick) that gives the surface a high
degree of wear-resistance.
The imaging takes place via magnetic imaging heads. Imparting a
magnetic pattern onto the image carrying surface is based on the
orientation of the magnetic dipoles within the material. The
orientation of the magnetic field within the domains is reversed
via an external magnetic field (H). This introduces a magnetization
(M) in the imaging layer, which creates a magnetic
field on the surface. The hysteresis loop between the magnetic
field strength and the resulting magnetization demonstrates that
despite outer field strength of zero, there is still residual
magnetism present. This means that the latent image is saved after
the magnetic pattern has been introduced to the drum surface and
can, in principle, be used to print the same image content several
times without the need for re-imaging (This effect has not really
been exploited yet, probably due to system design and destabilizing
effects within the material and the immediate environment that can
lead to poor quality in the print).
It is possible to erase the magnetic pattern impressed. This is
done by using a special erase magnet, which causes a constant
magnetic reversal of the domains during the hysteresis loop cycle
with alternating field strength and decreasing amplitude, until a
neutral non-magnetic surface is created (State: H = 0,M = 0).
The imaging head is in mechanical contact with the hard,
wear-resistant surface of the drum (to introduce a well-defined,
reproducible magnetic field pattern). The flux density is so great
on the narrow recording pole that the orientation of the magnetic
dipoles is changed, while on the broader pole for closing the
magnetic flux, the flux density does not create any significant
change to the polarization of the magnetic domains.
Bull/Nipson has had single-color high performance printing
systems based on the physical effect of magnetization on the market
since around 1985. The major technical challenge lay in the
development of imaging systems able to produce high resolution
images that were both reliable and at the same time economical.
The above picture displays the basic principle of magnetography
and shows the position of the developer. A single-component
magnetic powder toner is used. The core of the magnetic toner
contains iron oxide and is covered with colorant, which gives it
color. The toner is magnetized at the end of its manufacturing
process. The dipoles are oriented in the iron oxide through the
magnetic field. The quantity (volume) ratio of color coating to
core is around 40:60, meaning that the color of the
single-component toner is influenced significantly by the dark core
as a consequence of the iron oxide contained in it (magnetic
single-component toners for electrophotography have a low core
content of around 10%, which is sufficient for transport via
magnetic rollers).The single-component toner particles are
transferred to the magnetized surface of the imaging drum as a
result of the iron core. The high concentration of iron oxide in
the toner particles means that it is not possible to create pure
colors, particularly bright hues. It is therefore mainly used in
black and white printing or when printing with several, relatively
dark spot colors.
The transfer procedure of the toner onto the imaging drum is as
follows. The developer consists of a rotating magnetic roller that
takes the toner from the container. The toner is transported into
the direct vicinity of the imaging surface by a blade-like
component. The toner particles adhere to the imaging drum in
accordance with the magnetic field pattern. Since a surplus of
toner is present in the feed gap, other toner particles are also
attracted. This can lead to distortions and a lack of definition in
the image. A unit for magnetically enhancing image quality consists
of a rotating sleeve and a stationary permanent magnet in the core
that picks up any non-adhering toner particles (e.g., for improving
the sharpness) and feeds them back to the circuit. In addition
there is an extraction unit that removes any excessive toner
particles.
The application of toner onto the paper web takes place under
high pressure. The majority of the toner is transferred here and
the remainder must be removed via a cleaning device consisting of a
doctor blade and extraction system.
The print image is fixed by fusing the toner through heat
radiation. The heat can be applied to the reverse side of the paper
using heating elements. Additional radiant heat can be fed from the
image side to fix the image. The dark hues, which are typically
used in magnetography, ensure good heat absorption. So called flash
fusing units using impulse-commutated xenon lamps can be employed
to fuse and fix the print image.
Abstract: A method for printing by magnetography under
atmospheric conditions of relative humidity exceeding 65 or even
75% consists in transferring to a sheet of paper a fusible magnetic
ink in powdered form which is distributed on a temporary
magnetizable support in accordance with the configuration to be
produced, whereupon the ink is fixed by fusion on the sheet of
paper. The paper has a surface resistivity of at least 10.sup.10
ohms square and a relative smoothness of at least 20 Bekk. Claim:
What is claimed is: 1. A method of printing by magnetography under
ambient atmospheric conditions of high relative humidity which
exceeds 65 percent, the improvement comprising in which
amagnetizable, fusable, magnetic ink in powdered form is
transferred to a paper sheet and distributed on a temporary
magnetizable support in accordance with the configuration to be
reproduced, whereby the ink is fixed by fusion on the paper sheet,
whereinthe paper sheet employed has a surface resistivity of at
least 10.sup.10 ohms square under relative humidity conditions of
transfer of 50%, has a smoothness of at least 20 Bekk and comprises
a cellulosic web substantially free from whitening
agents,fluorescent dyes, bleaching agents, and electrolytes, the
cellulose fibers used for manufacturing said web being
substantially free of impurities, whereby precise magnetographic
printing can be obtained at high humidity. 2. The method of claim 1
in which the relative humidity exceeds 75 percent, said method
comprising using a paper sheet having a surface resistivity of at
least 10.sup.12 ohms square in a relative humidity environment of
50% and at least10.sup.10 ohms square in a relative humidity
environment of 75%. 3. A method according to claim 1 in which the
paper sheet has a porosity of the order of 200-300 measured in
accordance with the Bendsen method. 4. The method according to
claim 1 in which the paper sheet comprises (1) a cellulosic web
containing an inorganic filler selected from the group consisting
of talc, kaolin, and mixtures thereof, and (2) a starch-based
surface coating on thesurface to be magnetographically printed. 5.
The method of claim 1 in which said paper sheet defines a surface
coating free of inorganic materials. 6. The method of claim 5 in
which said paper sheet carries a surface coating of starch based
material. 7. A method of printing by magnetography under ambient
atmospheric conditions of high relative humidity which exceeds 65
percent, the improvement comprising in which a magnetizable,
fusable magnetic ink in powdered form is transferred to a
papersheet and distributed on a temporary magnetizable support in
accordance with the configuration to be reproduced, whereby the ink
is fixed by fusion on the paper sheet, wherein the paper sheet
employed has a surface resistivity of at least 10.sup.12 ohmssquare
under relative humidity conditions of transfer of 50 percent, has a
smoothness of at least 20 Bekk and comprises a cellulosic web
substantially free from whitening agents, fluorescent dyes,
bleaching agents, and electrolytes, the cellulose fibersused for
manufacturing said web being substantially free of impurities, said
paper sheet defining a surface coating which is substantially free
of
inorganic materials. 8. The method of claim 7 in which said
surface coating comprises a starch-based material. 9. The method of
claim 8 in which the relative humidity exceeds 75 percent, said
method comprising using a paper sheet having a surface resistivity
of at least 10.sup.12 ohms square in a relative humidity
environment of 50 percent and at least10.sup.10 ohms square in a
relative humidity environment of 75 percent. 10. The method of
claim 9 in which the paper sheet has a porosity of essentially
200-300, measured in accordance with the Bendsen method.
Description: This invention relates to magnetography or inother
words to a printing process involving the use of a magnetic drum on
which is produced a magnetic image of the impression to be formed,
whereupon particles of solid metallic ink generally known as a
"toner" are caused to adhere to said metallicimage, thus revealing
the recorded image. By pressing the drum against a sheet of paper,
the ink is transferred to the paper on which it is fixed by
heating. Fusible magnetic inks are employed for this purpose. When
it is desired to produce impressions by magnetrography in
environments having high relative humidity above approximately 50%,
grey results are usually obtained as a result of poor transfer of
the ink to the paper. The problem therefore consists in obtaining
sharply defined copies in environments which have high humidity but
are nevertheless usually encountered in residential premises in
temperature countries. Printing by magnetography is more
particularly advantageous for high-speed printing of documents
delivered by computers. Up to the present time, researches have
apparently been directed essentially to the nature and properties
of ink but the paper employed has consisted of either ordinary
paper or types of paper which have been specially studied for
printing byelectrography but have proved disappointing. When the
paper was exposed to relative humidity of the air exceeding 50%,
the printing result or impression was very pale or, in other words,
had low optical density. In the case of inks employed up to the
present time, magnetographic printing calls for the use of paper
having a low moisture content which has to be maintained by means
of an air-tight wrapping which protects the paper against ambient
humidityup to the moment of printing. In point of fact, however,
the printing machine must be capable of operating in
non-conditioned atmospheres. The aim of the invention is to
overcome the drawbacks of magnetography in highly humid
environments and to produce acceptable printed products without any
need for special precautions, even at high values of ambient
humidity.
The invention is directed to a method of printing by
magnetography under ambient atmospheric conditions of relative
humidity which may exceed 65%. This method consists in transferring
to a sheet of paper a fusible magnetic ink in powdered formwhich is
distributed on a temporary magnetizable support in accordance with
the configuration to be reproduced, whereupon the ink is fixed by
fusion on the sheet of paper. The distinctive feature of the method
lies in the use of a sheet of paper whichhas a surface resistivity
of at least 10.sup.10 ohms square under the conditions of relative
humidity of transfer and which has a relative smoothness of at
least 20 Beck. The invention also relates to a sheet of paper for
printing by magnetography under atmospheric conditions of relative
humidity which may exceed 75%. The sheet is distinguished by the
fact that it has a surface resistivity of at least 10.sup.10ohms
square as measured with the Keithley apparatus after exposure at
20.degree. C. in an environment having a relative humidity of 30%
during a period of one hour, then at 23.degree. C. in an
environment having a relative humidity of 50% over a periodof at
least ten hours, and that the paper has a relative smoothness of at
least 20 Bekk. It is an advantage to ensure that a sheet of paper
in accordance with the invention contains practically no whitening
agent and practically no electrolyte. In one embodiment, a sheet of
paper for magnetography in accordance with the invention has a
surface layer of mineral pigments in a non-hydrophilic binder on
the sheet face which is intended to take the impression. A mineral
pigment of this typeadvantageously consists mainly of calcium
carbonate in the form of powder which has a mean particle diameter
of the order of one micron and in which approximately 80% of the
particles have a diameter of less than approximately two microns.
The binder is advantageously constituted at least partly by a
substance of the group comprising the acrylate and styrene
copolymers, polyvinyl alcohol, the ureaformaldehyde resins without
either plasticizer or solvent. In another embodiment, use is made
of a sheet of paper having a porosity of the order of 200 to 300 as
measured in accordance with the Bendtsen method and a pH value
below 7. This corresponds to a sheet of paper without any special
coating andmade of paper pulps selected as a function of their
chemical purity or in other words practical absence of foreign
ions, especially sodium, potassium, chlorine, sulfur, and of their
high intrinsic surface resistivity. Refining of the paper pulp must
be reduced to a minimum, taking into account the mechanical
strength of the paper which it is desired to obtain. The proportion
of mineral fillers must be as high as possible within the limits of
mechanical strength of the desired paper. Finally, the paper must
be manufactured in a fairly acid medium.
The optical printing density achieved on a magnetographic
printer depends on the electrical surface resistivity at the moment
of printing (this factor being of major importance) but also on the
relative surface smoothness which must be higherthan 20 Bekk (this
factor being nevertheless of secondary importance). The values of
surface resistivity indicated in this description are those
measured by means of the Keithley apparatus with suitable
electrodes for measurements in "ohms square". In the case of paper
which is neither surface-pigmented nor coated, in other words in
the case of papers of practically uniform constitution throughout
their thickness, it is possible to establish a direct relationship
between the optical densityof the magnetographic printing images
and the surface resistivity. This relationship is materialized by
the curve shown in the single figure of the accompanying drawings.
This curve shows a very sharp increase in the optical density of
the printingimage between the levels of surface resistivity of
10.sup.10 and 10.sup.11 ohms square. The optical density of the
printing images can be considered as satisfactory above the value
of 1.0 and unsatisfactory below 0.8. The values of surface
resistivitywithin the range of 10.sup.10 to 5.times.10.sup.10 ohms
square can thus be considered as representing a resistivity
threshold above which the surface resistivity of the paper must be
situated at the moment of printing. Experience shows that the
majorityof papers have a resistivity below this threshold value
when they are subjected to atmospheric conditions in which the
relative humidity of environmental air is at least 55 to 65%. Such
papers are therefore unsuitable for magnetographic printing
inclimates in which the relative humidity exceeds 55 to 65%. The
surface resistivity is in fact a rapidly decreasing function of the
relative humidity of the paper at equilibrium. Broadly speaking,
any method for reducing the hygroscopicity of the paper or in other
words the moisture absorption capacity of the paper when it is
subjected to a given climate, will provide favorable conditions for
magnetographic printing. Alower water content in fact produces an
increase in resistivity and it has been observed that the logarithm
to the base 10 of the surface resistivity is a decreasing linear
function of the logarithm of the water content. The invention is
also concerned with the documents printed by magnetography on
papers in accordance with the invention. A more complete
understanding of the invention will be gained from the following
description of a few non-limitative examples of embodiments in
accordance with the invention. EXAMPLE I A paper pulp is prepared
by introducing upstream of the paper machine the substances which
constitute the pulp suspension:
bleached hardwood chemical pulp--52% bleached coniferous or
softwood chemical pulp--35% mixture of talcum powder and china clay
in equal parts--13% sizing products and retaining agents in the
usual quantities. The surface of the sheet of paper thus formed is
coated by means of a so-called "surface sizing press" with a
preparation containing the following products: 420 kg of powdered
chalk having a mean particle diameter of 1 micron in which 80% of
the particles have a diameter of less than 2 microns, of the type
marketed by the Omya Company under the trade name of Omyalite, 150
kg of a 50% aqueous suspension of a copolymer of acrylate and
styrene which is free of plasticizers and solvents, of the type
marketed by the BASF Company under the trade name of Latex S 320 D,
10 kg of a 40% anionic aqueous suspension of a copolymer of
acrylates of the type marketed by the BASF Company under the trade
name of Acrosol, 5 kg of a polyvinyl alcohol having a degree of
hydrolysis higher than 98 and low viscosity within the range of 7
to 11 centipoises, this viscosity being measured in a 4% aqueous
solution at 20.degree. C., 20 kg of an anionic urea-formedalhyde
resin in a 63% solution in water of the type marketed by the
Rousselot Company under the trade name of Resine 41-22, 1 kg of a
dispersing agent of the type which has a polyacrylamine base and
sold by the BASF Company under the trade name of Polysel. The
foregoing composition is diluted with water up to 1000 kg. No
fluorescent whitening agent or other optical colorants. This
preparation is deposited on the sheet in a proportion of
approximately 16 g/m.sup.2, namely 8 g/m.sup.2 on each face.
Finally, the sheet is subjected to a calendering operation in order
to have a surface smoothness which is greater than 20 Bekk. EXAMPLE
II
A paper pulp is prepared with the same materials as in Example
I. The sheet of paper thus formed is subjected to a surface coating
operation by means of a trailing-blade coating machine which has
higher performance than the surface sizing press of Example I and
makes it possible to apply a coating to a singleface with more
uniform deposition. The coating operation is carried out with a
basic preparation containing the following products: 350 kg of
powdered chalk having a mean particle diameter of 1 micron in which
80% of the particles have a diameter of less than 2 microns, of the
type which is commercially available under the trade name Omyalite
and marketed by the Omya Company, 140 kg of a 50% aqueous
dispersion of an acrylate and styrene copolymer which is free of
plasticizers and solvents, of the type which is marketed by the
BASF Company under the trade name S 320 D, 6.5 kg of a 40% anionic
aqueous suspension of a copolymer of acrylates which is free of
plasticizers and solvents, of the type sold by the BASF Company
under the trade name Acrosol, 4.5 kg of a polyvinyl alcohol having
a degree of hydrolysis which is higher than 98 and a low viscosity
within the range of 7 to 11 centipoises, this viscosity being
measured in a 4% aqueous solution at 20.degree. C., of the type
marketed by theRhone-Poulenc Company under the trade name of
Rhodoviol 8.20, 15 kg of an anionic urea formaldehyde resin in a
63% solution in water such as the resin marketed by the Rousselot
Company under the trade name Resine 41-22, 1 kg of dispersing agent
of the type marketed by the BASF Company under the trade name of
Polysel. The preparation is diluted to 1000 kg by addition of water
and any introduction of bleaching agents or other optical agents is
avoided. A deposition of the order of 12 to 15 gr/m.sup.2 is
carried out on the face to be printed. Finally, the sheet is
calendered in order to be endowed with a surface smoothness which
is greater than 20 Beck. EXAMPLE III A pulp is formed by feeding
the following materials into the upstream end of the paper machine:
bleached hardwood chemical pulp containing less than 30 visible
impurities per kg--62%
bleached coniferous or softwood chemical pulp containing less
than 30 visible impurities per kg--20% talcum powder--18% a minimum
quantity of conventional acid sizing products, cationic retaining
agent (cationized starch as sold by the Roquette Company under the
trade name of Cato). Any fluorescent dye or other bleaching agents
are completely avoided and refining is limited to a minimum. By
means of a surface sizing press, a coating operation is performed
with a starch preparation having a base of potato starch degraded
by enzymation to a concentration of 10% without any fluorescent dye
or any electrolyte. The paper is calendered in order to give it a
surface smoothness which is greater than 30 Beck. A porosity of the
finished paper is measured and must be within the range of 200 to
500 as measured in accordance with the Bendtsen method. This
porosity is the indication of a low degree of refining in
accordance with the known law whichrelates the degree of refining
or beating to the porosity, this latter being a decreasing function
of the degree of refining. Furthermore, this paper which is
manufactured in an acid medium has a pH which is lower than 7 as
measured by the method of "determination of the pH of aqueous
extracts of papers" as described in the AFNOR standard Q 03 005 or
the ISO/DISstandard 6588. The table given hereunder shows the
analytical results of papers in accordance with the invention as
produced in accordance with the foregoing examples I, II and III.
______________________________________ Example Example Example I II
III ______________________________________ Weight g/m.sup.2 80 90
95 Surface resistivity (Keithley in .OMEGA..sup.2 : (1) 50% RH 1.15
.times. 1.6 .times. 12.7 .times. 10.sup.12 10.sup.12 10.sup.12 (2)
75% RH 0.98 .times. 6 .times. 7 .times. 10.sup.10 10.sup.9
10.sup.10 Whiteness: (1) Xenon with 97.8 93 81.6 fluorescence, (2)
Xenon without 80.6 81.6 81.6 fluorescence, Burst factor 22 18 30
(Mullen test) Load at break 4000 3800 6200 Front 25.4 60 40 Surface
side smoothness Reverse 40 30 40 side (Bckk test) Ash content at 24
26 15.8 800.degree. C. Optical density: (1) 50% RH 1.28 1.15 1.26
(2) 75% RH 0.96 0.82 1.12 ______________________________________ It
will be noted that, in Example I, the surface resistivity of the
paper at 75% relative humidity (RH) is only 0.98.times.10.sup.10
ohms square although it is wholly suitable for printing by
magnetography.
However, by reason of the fact that the spacing of the
electrodes for measuring surface resistivity is considerably
greater than the thickness of the paper, the Keithley apparatus
appears to be incapable of measuring the surface resistivity
alonewithout measuring the resistivity of the interior of the paper
at the same time unless both the surface and the interior are very
different from an electrical standpoint. However, in the case of
pigmented paper of the type considered in Example I andreally
having an insulating surface which attains the threshold value of
resistivity at 75% relative humidity as required in accordance with
the invention, the desired result is obtained although the Keithley
apparatus is not capable of measuring thisresistivity threshold.
The use of calcium carbonate (chalk) as a filler is conducive to
the obtainment of high resistivity. However, it cannot readily be
employed in an acid medium on account of its decomposition. Under
the conditions of exposure mentioned in the foregoing, namely
successively at 20% and 50% relative humidity, a paper in
accordance with Example III must have a surface resistivity greater
than 3.times.10.sup.12 ohms square. This paper is uniform
throughout its thickness and the surface resistivity--density
relation is wholly satisfied in this case despite the limitations
of the Keithley apparatus, in contrast to the coated and pigmented
papers of Examples I and II. As will be readily apparent, the
invention is not limited in any sense to the examples described in
the foregoing. Depending on the applications which may be
contemplated, the invention may be extended to many alternative
embodiments within thecapacity of those versed in the art without
thereby departing from the scope or the spirit of the
invention.
Nipson's proven technology Underlying the success of Nipsons
solutions is the combination of its proprietary dry toner
magnetography and cool xenon flash fusing. The first press using
magnetography was commercialized in 1985. Building on the solid
foundations of our proven technology, our systems have been
continuously developed, redesigned, and improved upon to provide
you with an unmatched mix of quality, productivity, and total
application flexibility at an impressively low total cost per page.
When you choose Nipson technology, you are reaping the benefits of
decades of innovation and development. Our DIGIFlex and VaryPress
ranges both come with all the features that have become Nipsons
trademark.
Abstract: Magnetographic copier having a movable carriage on
which the process stations for recording, developing, transferring
and cleaning are mounted. A ribbon of magnetic tape is threaded
through the process stations and is held stationary during the
image processing, so that the movement of the carriage causes the
tape to pass all of the process stations. A CCD array scans
segments of a fixed original document and then returns to a start
of scan position where it is stepped. The carriage and CCD array
are concurrently stepped a distance substantially equal to width of
a segment prior to the next scan. The CCD array and carriage are
connected by cable and move concurrently. The elements of the CCD
array are connected in a one-to-one manner with elements of a
magnetic recording head at the recording station. Start of scan is
initiated by sensing accurately placed holes in the magnetic tape
and width of scan is controlled by marks on a code strip which are
detected by the CCD array elements to adjust the number of elements
enabled. Claim: We claim: 1. A magnetographic carriage printer for
reproducing documents placed on a fixed platen thereof when a
reproduction mode of the printer is activated, comprising: means
for scanning segments of a document placed on the fixed platen, the
scanning means moving from a start-of-scan position across the
document in a scanning direction to an end-of-scan position and
returning to the start-of-scan position, saidscanning means being
adapted to scan uniformly wide segments of the document and to
convert the scanned segments into digital image data signals; means
for moving the scanning means in a direction transverse to said
scanning direction upon each return of the scanning means to the
start-of-scan position during the reproduction mode, the moving
means relocating the scanning means for adistance equal to the
width of one segment so that segments of said document are
sequentially scanned until the entire document has been scanned; a
magnetic tape having a magnetizable surface for recording latent
magnetic images thereon, the width of the magnetic tape being
determined by the width of the segment scanned by the scanning
means; a movable carriage having mounted thereon a magnetic
recording head for receiving the digital image data signals from
the scanning means and for recording them on the magnetic tape as
latent magnetic images, a means for developing the latentmagnetic
images with toner particles, a means for transferring the developed
images to a copy medium, and a means for cleaning any residual
toner particles from the tape to prepare it for reuse, the magnetic
tape being positioned in operativerelationship with the recording
head, developing means, transferring means and cleaning means;
means for interconnecting the scanning means to the carriage so
that they move concurrently and in a predetermined, fixed relation
to each other; means for mounting the magnetic tape, said means for
mounting being adapted to hold the tape stationary during the
reproduction of a document by the printer, so that as the carriage
moves the tape passes by the recording head, developing
means,transferring means and cleaning means;
means for activating said scanning means at a predetermined time
as it moves from a start-of-scan position to scan each segment of
the document to be reproduced, so that the beginning and ends of
the transferred image segments are accuratelyaligned on the copy
medium; and means for controlling the width of the segment scanned
by said scanning means to insure that each scanned segment has the
same width, so that the transferred image segments are accurately
stitched together to form a high quality reproduction ofthe
document. 2. The printer of claim 1, wherein the means for scanning
is a charged coupled device (CCD) adapted for scanning and return
movement and means for moving said CCD, the CCD having a pluarlity
of sensing elements in a linear array which areconnected to
individual, associated recording elements of the magnetic recording
head in a one-to-one manner. 3. The printer of claim 2, wherein the
means for moving the CCD in a transverse direction is a movable
housing having both the CCD and carriage mounted therein, said
housing being adapted for movement in a direction transverse to
that of the CCDscanning direction and having drive means capable of
moving the housing substantially equal distances in the transverse
direction at the conclusion of each CCD scan and return until said
document has been entirely scanned and recorded on the
magnetictape. 4. The printer of claim 3, wherein the means for
interconnecting the CCD to the carriage is a cable, said cable
being mounted for movement and arranged so that movement of the CCD
causes the carriage to move in an opposite direction. 5. The
printer of claim 4, wherein the means for mounting the magnetic
tape comprises: a supply spool and a take-up spool, said spools
being rotatably mounted on spindles, said spindles being located
outside the carriage and mounted on the movable housing so that the
tape travels concurrently with the CCD and carriage in
thetransverse direction. 6. The printer of claim 5, wherein the
means for activating the CCD comprises: placing accurately spaced
holes in tape; a photosensor for sensing said tape holes and for
producing a signal indicative thereof, the photosensor being
located at a predetermined location in the vicinity of the
recording head; and means responsive to the photosensor signal to
energize the CCD, so that each CCD scan initiates tape recording by
the recording head at precisely the same location on the tape to
assure proper margin alignment of each developed image
segmenttransferred to the copy medium. 7. The printer of claim 6,
wherein the means for controlling the width of the segment of the
document scanned by said CCD comprises:
providing more CCD sensing elements and more associated
recording elements than are necessary for segmental scanning and
recording of the document; an elongated code strip accurately
mounted on the fixed platen along the edge thereof which is
perpendicular to the CCD scan direction and which edge is adjacent
the CCD at its start-of-scan position, the code strip having
equally and accuratelyspaced marks thereon, each of said marks
being spaced so that at least one of the sensing elements of the
CCD sense a one of the marks before each segmental scan of the
document by the CCD; and means for enabling a predetermined
contiguous number of CCD sensing elements which immediately follow
those sensing elements which sense said code strip marks, whereby
the scanning elements which sense the code strip mark are not
enabled and atleast one CCD sensing element on the other end of the
sensing array is not enabled. 8. The printer of claim 7, wherein
the printer further comprises; means for dispensing a fresh portion
of magnetic tape from the supply spool; means for taking up the
previously used portion of the magnetic tape on the take-up spool;
means for marking the beginning of the fresh portion of tape, said
marking means applying a removable mark on the tape; means for
sensing the tape mark and providing a signal indicative of said
sensed mark, the sensed mark signal being used to stop the tape
dispensing and taking up means so that the fresh portion of the
tape becomes stationary again relative tothe movable housing; and
means for removing the tape mark prior to that portion of the tape
reaching the transferring means, so that the tape mark is not
transferred to the copy medium. 9. The printer of claim 8, wherein
the means for transferring the developed images comprises: a
pressure transfer roller which is moved from a transfer position to
a non-transfer position when the carriage has completed a path of
travel caused by the movement of the CCD from its start-of-scan to
the end-of-scan position; and a fixed support for receiving and
holding the copy medium stationary while the developed images are
being serially received from the magnetic tape by the copy medium.
10. The printer of claim 9, wherein the printer further comprises
means for selectively receiving digital image data signals from
sources outside the printer instead of from the CCD at the option
of a user of
said printer. 11. A magnetographic carriage printer which
functions as a real-time raster input scanner/raster output scanner
(RIS/ROS) when reproducing copies of documents placed on a fixed
platen thereof comprising: a charge coupled device (CCD) having an
array of sensing elements and adapted to scan a document on the
platen in a scanning direction one segment at a time, the CCD
returning to a start-of-scan position after scanning each segment
and beingstepped in a direction transverse to the scanning
direction for a distance of one segment width before scanning the
next segment in a continual scan, step and repeat manner until the
entire document is scanned; a fixed substrate for supporting a copy
medium; a ribbon of magnetic tape being held stationary during the
reproduction of documents; a movable carriage containing a magnetic
recording station, a developing station, a transfer station and a
cleaning station, the carriage being connected to the CCD for
concurrent but opposite movement therewith during the scanning and
return ofthe CCD and for concurrent movement in the same direction
of the CCD during the transverse stepping of the CCD; said magnetic
tape being threaded through the stations, so that the movement of
the carriage causes the tape section at the recording station to
pass through all of the stations sequentially prior to the return
of that tape section to itsoriginal position when the carriage
returns to the start-of-scan position with the CCD; said recording
station comprising a thin-film recording head having an array of
recording elements connected to the CCD sensing elements in a
one-to-one fashion, so that the digitized image data from each CCD
element is received and recorded onthe magnetic tape by an
associated recording element; said transfer station having a
retractable pressure transfer roller which retracts when the
carriage is moving in the return direction and which urges the
transfer roller with the magnetic tape therebetween into contact
with the copy medium whenthe carriage is moving in the scan
direction to transfer and print the developed magnetic image on the
tape of the copy medium; means for registering the start-of-scan by
the CCD with the start-of-recording by the recording head by
electronically sensing fixed positions on the magnetic tape; and
means for enabling precise number of predetermined CCD elements and
associated recording head elements by electronic sensing of fixed
code marks by the CCD elements prior to each scan, so that the
problems of carriage and CCD registration aresolved electronically
and that the transferred segments of developed images are
accurately aligned on the copy medium during transfer to produce a
high quality copy of the documents reproduced.
12. A magnetographic carriage printer having a thin-film
magnetic head with an array of recording elements for copying
documents placed on a fixed platen of the printer when in a copying
mode and for printing digital data streams or videosignals supplied
from an outside data source when in a printing mode, the carriage
printer comprising: means for switching the carriage printer to
either the copying mode or the printing mode; a movable carriage in
which all process stations involved in recording and developing a
latent magnetic image on ribbon of magnetic tape are mounted on
said carriage, the carriage being movable from a start-of-scan
position to an end of scanposition and return for one scan cycle,
and the carriage being stepped in direction transverse to the scan
direction after each scan cycle; the ribbon of magnetic tape being
threaded through the process stations and held stationary while the
printer is copying or printing, so that the tape passes from one
process station to the next as the carriage moves; a charge coupled
device (CCD) having an array of sensing elements for scanning the
document one segment at a time, each CCD element corresponding to
one of the magnetic head elements in a one-toone arrangement, so
that the scanned segment of thedocument, which is digitized by the
CCD, is recorded on the tape by the magnetic head, the CCD being
movable from a start-of-scan position to an end-of-scan position
and return for one scan cycle to scan one segment of the document,
and the CCD beingstepped in a direction transverse to the scan
direction after each scan cycle for a distance equal to the width
of a segment, the scanning and stepping of the CCD being continued
until the entire document has been scanned; means for connecting
the CCD to the carriage in order that they move in unison and in
predetermined directions for predetermined distances; a copy medium
being held stationary on a fixed support adjacent the transfer
station to receive a developed image representing one segment of
the document for each scan cycle of the carriage; means for driving
the CCD and carriage during the scan cycles and stepping movements;
means for determining the start-of-scan positions of the CCD; means
for selectively enabling the CCD elements and corresponding
magnetic head elements to enable accurate segments of the document
to be scanned and recorded, so that the transferred developed
images are stitched together to produce a highquality copy of the
document; and means for controlling the operation of the process
stations, driving means, determing means and enabling means in
timed relation with each other. Description: FIELD OF THE
INVENTION
The present invention relates to magnetographic printers or
copiers and more particularly to a magnetographic printer or copier
with a carriage type architecture which utilizes a thin film
recording head array to print bands of an image in a stepand repeat
manner until the entire image has been created. DESCRIPTION OF THE
PRIOR ART With today's discrete record head technology, such as
described in U.S. Pat. No. 3,487,391 to J. H. Todt, creating a full
8-1/2 by 11 inch, high resolution imaging is inherently a slow
process. Elaborate mechanical systems must be employed inan effort
to minimize the recording time. Such measures inevitably add to the
cost of a magnetographic printer. U.S. Pat. No. 3,487,391 mentioned
above is directed to the construction and method of making a
highdensity, discrete magnetic-recording head. It is made up of
minute, individual heads, attached side-byside and insulated from
each other. Thecoils are angularly staggered from each other to
allow proper spacing, there being approximately 100 heads for each
0.57 inch of transducer head width. U.S. Pat. No. 4,176,362 to A.
M. Nelson discloses a high density magnetic image recording head
which is constructed using printed circuit techniques. The head
includes a large number of recorder elements to enable recording
across an eightinch width of magnetic tape. After the full page
width images are formed on the tape, the magnetic tape moves past a
transfer station where the magnetic images are transferred to a
magnetic drum and developed with toner. Then the developed images
aretransferred to paper. Multiple copies of the images can be made
by moving the magnetic tape out of contact with the drum and
redeveloping the magnetic latent image on the drum after each
transfer of the developed image to paper. Thin film recording heads
greatly reduce the recording time over what is presently possible
and do so at a significantly reduced cost. For a general discussion
of thin film recording heads refer to the article in the Honeywell
Computer Journalby W. Chynoweth et al., published in 1973 on pages
103 to 117, entitled "Pedro, A Transducer-Per-Track Recording
System with Batch-Fabricated Magnetic Film Read/Write Transducers."
Thin film heads can be fabricated on a single substrate at
densities of75 or more to the linear inch, and single arrays of one
inch in length are available today. By interleaving several such
arrays, 300 pixels or spots per inch resolution can be achieved to
keep the recording time for high resolution images to a minimum.
Utilizing the thin film head technology, an acceptable low-cost
magnetographic copier having high resolution and graphics
capability is possible, if a small width magnetic tape system could
be used which has good registration of the individualrecord tracks
that make up the image and good registration of the multiple
segments or bands of the developed image can be maintained as it is
transferred to the paper. Most important, such a system must be
inexpensive, simple and reliable to becommercially feasible.
U.S. Pat. No. 3,740,265 to G. D. Springer relates to an improved
magnetic image transfer technique in a printer using a narrow
magnetic tape system from which information is transferred to a
record sheet on a line-by-line basis. This printerutilizes an
endless magnetic tape supplied from a cartridge that is supported
on rollers in a continuous loop and is advanced by one or more tape
drives. The tape follows a path through an encoding station,
developing station and a transfer station. Information to be
printed is received by the encoding station in the form of a train
of pulses. The encoding station includes a multitrack magnetic
recording head that is adapted to record magnetic bits on the tape
at selected positions with a standardcharacter matrix to form each
given character to be printed. The recording head is controlled by
a character generator that assigns the matrix positions for a given
character and that is responsive to a decoder circuit. After a
magnetic character imageis formed the tape is driven through a
developing station and then advanced to the transfer station where
a pressure plate moves the tape into contact with a record sheet
and transfers the developed image on a line-by-line basis. As the
tape isassociated with the record sheet, the magnetic images on the
tape are erased to enhance transfer. The tape is then returned to
the cartridge for reuse. U.S. Pat. No. 3,735,416 to O. J. Ott et
al. relates to a magnetographic printing device wherein data is
entered onto an endless magnetic tape as a matrix of recorded
segments. A magnetic ink or toner is applied to the recorded images
and issubsequently transferred onto paper or other receiving
surfaces. Individual characters can be printed one at a time or
entire lines of data can be imprinted. Information to be printed
can be applied to the printing system from a computer,
manuallyoperable keyboard or from a remote source via a telephone
line or other communication link. At a printing station, the toner
is transferred from the recorded portions of the tape onto a
confronting surface by means of a low energy mechanism. The tapecan
be incremented about its path, so that transfer of the toner from
the tape can be accomplished during the dwell interval of the
intermitten tape motion. SUMMARY OF THE INVENTION It is the object
of this invention to provide a low-cost, magnetographic copier
having relatively high resolution and graphics capability. It is
another object of the invention to provide a magnetographic copier
which functions as a real-time raster input scanner/raster output
scanner (RIS/ROS) in producing the latent magnetic images on
magnetic tape or as an electronic outputdevice which accepts
electroniclly created images and, in response thereto, produces
latent magnetic images thereof on magnetic tape. It is a further
object of this invention to provide a magnetographic copier which
scans a lateral section or band of an original document, write that
band of the original document as a latent image on a stationary
ribbon of magnetic tape andtransfers the developed image to a
receiving substrate in a sequential step and repeat manner until
the entire original document is reproduced. It is yet another
object of this invention to provide a magnetographic copier having
a movable carrier, wherein the problems of registration of the
carriage in both the lateral and longitudinal directions are
solved electronically. In the present invention, a
magnetographic copier/printer has a movable carriage in which all
of the process stations involved with recording and developing of a
magnetic latent image are mounted on the carriage and a ribbon of
magnetic tape isthreaded through these stations from supply and
take-up spools which are stationarily mounted outside of the
carriage. The tape is of a width compatible with the most
convenient size of thin film head array, which thus determines the
width of the bandsthat make up the final image. During copying, the
tape is held stationary and the carriage is allowed to translate.
As the carriage moves, the tape passes consecutively from one
process station to the next. As a result of holding the tape
stationary,problems of tape registration are avoided which would
otherwise require expensive arrangement to maintain accurate
carriage motion and carriage registration. A standard charge
coupled device (CCD) array is used to scan the original document to
bereproduced which digitizes the image and send the digitized data
to the thin film head array. The data is shipped in a serial
fashion between the CCD array and the thin film heads. Each CCD
element would correspond to a thin film head array element ina
one-to-one arrangement. After a section of the original document is
recorded on the tape, the image is developed and printed on a
recording medium such as paper. The scanning, imaging and printing
of each succeeding segment of the original documentis preferred
until the entire document is printed on the recording medium. Means
are selectively available for switching the input to the thin-film
head array from the CCD array to a digital data stream suppled by a
computer or other similar source. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view diagram of the magnetographic copier/printer
of the present invention. FIG. 2 is a partial plan view of a
schematic representation of the magnetographic copier/printer of
FIG. 1 showing the CCD array and the printed code strip used in
electronically registering the CCD array. FIG. 3 is an enlarged
portion of FIG. 2 showing the CCD elements which sense the code
strip. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 depicts a
side-view diagram of the magnetographic carriage copier/printer 10
of the present invention. All of the process stations involved with
recording and developing a magnetic latent image on a ribbon of
magnetic tape 18 are mountedwithin a carriage 13. The magnetic tape
18 is threaded through the process stations and each end portion is
wound, respectively, on a supply spool 19 and a take up spool 20.
The spools are rotatably mounted on spindles 21 which are mounted
outside thecarriage 13 on side walls 61 (one shown) of movable
housing 60. The tape 18 is of a width compatible with the most
convenient size of the thin-film magnetic head array 22, which, in
the preferred embodiment, is between 1 and 2 inches. The tape
width,of course, determines the width of the successive and
sequential bands or segments of the original document that are
transferred from the tape to a copy recording medium 16, such as
paper, to form and make up the final composite image that
represents acopy of the document 15. The process stations are
mounted in the carriage 13 in the following order, first, the
recording station comprising a thin-film, magnetic-head array 22,
the development station 26, the transfer station 28 having a
pressure transfer roller 29, anda cleaning station 30. The
developing station may be of any magnetic development type which
applies magnetic toner particles 41, to the latent magnetic image,
but preferably is one having a magnetic brush 27 to bring the toner
particles into contactwith the latent image. The cleaning station
30 may be any one of a number of well-known configurations, but a
two station cleaning arrangement is preferred having the residual
toner first vacuumed off the tape by a vacuum system 31 via nozzle
34 andthen removing the remainder of the toner particles by a
relatively slow moving web 35 in pressure contact with the tape.
During copying, the tape 18 is held stationary by the supply and
take-up spools 19, 20 and the carriage 13 translates in the
direction of arrow 24, beginning from a start-of-scan position
indicated by dashed line 33. As the carriage moves, itcan be seen
that the tape will pass consecutively from a position confronting
the head array 22 through the various process stations one after
the other. As a result of holding the tape 18 stationary, problems
of tape registration are avoided, as willbe more fully understood
later. The charge coupled device (CCD) array 32 is connected by a
cable 14 to the carriage 13, so that when it moves in one
direction, the carriage must move in the opposite direction. This
direction of scan by the CCD 32, causes the head array 22 toproduce
a wrong-reading latent image on the tape. Therefore, the image
transferred, after development, to the paper will be a
right-reading image. The CCD array in its start-of-scan position is
to the right of the original document 15, as viewed in FIG. 1, and
the carriage 13 is positioned generally to the left of the
document. A plane passing through the axis of the pressure roller
29 inthe transfer station 28 is perpendicular to the document 15
and intersects the plane of the platen 23 holding document at the
left-hand edge thereof. As the CCD begins a scan, the CCD scans a
segment of the document from right to left. The carriage, onthe
other hand, moves from left to right, the latent magnetic image
being recorded on the tape in real time. The carriage 13 may be
mounted in any well-known manner so long as it may translate back
and forth in the direction of arrow 24 under the force of cable 14.
In FIG. 1, the carriage is depicted as slidingly mounted on a pair
of shafts 62 (oneshown). The shafts 62 are are mounted in lower end
walls 63 of the movable housing 60. The original document 15 is
positioned on the transparent platen 23 and remains stationary
while it is being scanned by the CCD 32, one segment or band at a
time. The CCD array is adapted to operate as a raster input scanner
(RIS) and each element corresponds to an element in the thin film
magnetic head array 22. Accordingly, there are about 300 elements
per inch in both CCD array and head array which areconnected in a
one-to-one arrangement. The band of image scanned by the CCD array
is digitized in a manner well-known in the art and sent to the
respective elements of the magnetic head arrays. The data between
the CCD array and the magnetic head arrayis shipped in a serial
fashion.
As the CCD array 32 scans a segment of the document 15, the
carriage 13 is translated in the opposite direction by the cable 14
which connects the CCD array to the carriage. The carriage movement
causes the magnetic tape 18, which is heldstationary, to be moved
sequentially through the process stations. After the first scan,
the carriage 13 and CCD array 32 return to the start-of-scan
position, where they are stepped in a direction transverse to that
of the scan direction for a distanceequal to that of the width of
the segment scanned. This procedure is repeated until the entire
document is scanned, recorded and printed on paper. The tranverse
or lateral stepping of the carriage 13 and CCD 32 may be done in
any manner well known in the art, but in the preferred embodiment
shown in FIG. 1, this is accomplished by mounting them in movable
housing 60. Housing 60 has racks64 mounted on the bottom of
intermediate floors 65 and the housing is translatingly supported
by gears 66 mounted on the stationary main frame 68 of the printer
10 which engages the racks. The top side of movable housing 60 is
guided by slide rails 67. Each time the carriage 13 moves a full
scan cycle (e.g., from the start-of-scan to the end-of-scan and
back), the latent image is recorded on the magnetic tape 18 as the
tape moves by the head array 22. The tape continues to move past
thedeveloping station 26, where the latent magnetic image is
developed by toner particles 41, around the pressure transfer
roller 29, where the developed image is pressure transferred to the
paper 16 on fixed support plate 39, and through the cleaningstation
30 where the residual toner particles are removed. The pressure
transfer roller 29 is lifted by means well known in the art out of
contact with the paper 16 when the carriage 13 and CCD array 32 are
returned to the start of scan position. Themovement by the pressure
transfer roller 29 avoids background and ghosting problems that
otherwise would appear in subsequent recording and printing. Prior
to the second scan by the CCD array 32, the CCD array and carriage
13 are stepped over a distance of one scanning width via movable
housing 60 by a stepper motor 48, which rotates one of the gears
66. Thus, gears 66 through racks 64laterally steps the movable
housing 60. The direction of movement of the movable housing
relative to FIG. 1 is in a direction perpendicular to the direction
of the carriage 13 and CCD array 32 movement and in a direction
into the surface of FIG. 1. Thedistance stepped is one scan width,
hereinafter referred to as lateral movement or stepping. The
carriage and CCD array lateral movement is relative to both the
document 15 being scanned and the paper 16 receiving the developed
image on fixed support39. This step and repeat operation is
repeated until the entire image has been printed. After the last
sequential segment of the image is transferred and the entire image
is on the paper 16, the paper is ejected past a means for fusing
the tonerparticles 41 forming the image on the paper, such as by a
radiant fuser 17. From the fuser 17, the paper 16 with a replica of
the original document thereon is moved to a collection tray 36.
Periodically, it may be desirable to use a fresh section of
magnetic tape 18. For example, the magnetic tape may become worn or
scratched, so that poor copy quality reproductions are being
encountered. When a new segment of tape is to bedispensed from the
supply spool 19, a synchronizing track record head 38 writes a mark
on the edge of the tape. For subsequent imaging with this new
section of tape,
this signal will be the clock that gates the CCD array 32 and
the magnetic head array22; that is, the copier will not start
another scan by the CCD array until a photosensor 40 observes that
the mark written by the track record head 38 has advanced thereby.
The replacement of a segment of magnetic tape may be done
automatically after apredetermined number of imaging cycles and/or
manually by the operator. New sections of tape 18 are never
advanced while the copier 10 is in the process of scanning and
printing an original document 15 or in the time between the
printing of successivebands or segments of the same document. As
soon as the photosensor 40 observes the mark by the track record
head 38, a signal is generated to stop the dispensing of the
magnetic tape 18 from the supply spool. The supply spool is spring
biased, when itis not dispensing tape, to keep a proper tension of
the tape around guide rollers 11 and 12 and the pressure transfer
roller 29. The take-up spool 20 is operated by a clutch and motor
42 when a new segment of tape is to be advanced. The
photosensorsignal also de-energizes the take-up spool motor 42. The
track record mark will stop at a location just below the head array
22, and will be cleaned off by a special cleaning station 44 before
the next developed image on the tape 18 reaches the transferstation
28. Spaced at periodic intervals along the tape 18 are holes (not
shown) which serve as a "start" of writing" indication. These holes
will be placed in the magnetic tape 18 during manufacture. As the
carriage 13 begins a traverse or scan cycle inresponse to a scan by
the CCD array 32, an optical sensor 43 detects the edge of the next
hole in the tape and, upon detection, enables both the CCD array 32
and the magnetic head array 22. From scan-to-scan, therefore, the
start of scanned segments ofthe document 15 should line up, since
the start pulse is derived from the tape (that is tape holes,)
which tape is never moved during the scanning/printing operation.
Referring to FIG. 2, registration in the lateral stepping direction
Y is achieved through the use of a printed code strip 46 rigidly
mounted on the stationary platen frame (not shown) of the copier 10
during manufacture and assembly thereof. Thecodes comprise a series
of dark areas 47 spaced along the code strip 46 at intervals
equivalent to the nominal distance of CCD scan width and also one
lateral step or segment width by the carriage 13 and CCD array 32
in movable housing 60. When thecarriage 13 is in the start-of-scan
position 33, the CCD array 32 will "see" this code strip. A
stepping motor 48 is used to drive the carriage 13 and CCD 32 via
movable housing 60 in the lateral direction Y, thus, insuring that
each lateral step downthe original document 15 will nominally be
the correct distance. However, because mechanical system errors are
always present, the movable housing 60 may not move exactly the
same distance for each lateral movement. If the movable housing
moves thenominal distance, then some number of CCD elements 37 on
one end of the array, e.g., 15, will be able to see the black area
47. If the movable housing and thus the carriage 13 and CCD 32 move
some distance greater or lesser than the nominal distance,then a
greater or lesser number of CCD elements 37 will see the black area
47. From this information, an electronic controller or
microprocessor 50 will be able to calculate the exact position of
the carriage 13 and CCD 32 relative to the elements 37and the
document 15, prior to scanning by the CCD in the X direction. In
the example above, the 15 CCD elements 37 that see the black area
47 of the code strip 46 will correspond to an associated 15
thin-film magnetic head elements. These 15 elements serve as a sort
of
buffer at the edge of the image area on themagnetic tape. When
the carriage and CCD are moved the nominal distance for one lateral
scan step and 15 CCD elements on one end of the array sees the
black area, they are not enabled for sensing. The associated 15
thin-film head elements are likewisenot enabled for recording. If
the distance moved is something other than the nominal distance,
the electronic controller 50 will enable or disable a greater or
lesser number of CCD elements 37 and associated thin-film head
array elements to insureproper stitching between scanned segments
of the original document 15 copied. During normal operation a
certain number of elements on each end of the CCD array 32 are not
used. Referring to FIG. 3, the CCD array elements 37 are shown as a
linear array of 300 elements one inch wide. If the carriage
translates in thelateral direction Y the exact distance, CCD
elements numbered 15 through 285 are enabled and used for the next
scan segment of the document because elements numbered 1 through 15
see the black area 47. If the movable housing containing carriage
13 andCCD 32 moves some distance greater or lesser than the exact
distance, the controller 50 can determine the position of the CCD
relative to code strip 47 by the number of CCD elements 37 which
sees the black area 47. Depending on the distance moved,
thecontroller 50 will enable 270 consecutive CCD elements, but the
precise elements enabled vary depending on the number which see the
black area 47; e.g., the elements 37 which are enabled may be CCD
elements numbered from 10 through 280 or from 30 through300 or from
5 through 275 etc. Since each CCD element 37 corresponds to a
discrete magnetic recording head element, only those recording head
array elements which match enabled CCD elements will be enabled.
This method provides for proper stitching between scanned segments
of the original document, and, ultimately, the proper stitching
between the developed images transferred serially to the paper 16
to form a copy of document 19. Copy paper 16 is provided from a
supply tray 45 located below the carriage 13. At a start of scan by
the CCD array 32, a sheet of paper 16 is fed from the tray 45 by
well known means and registered on fixed transfer plate 39 where
the paper willserially receive the image segments of the original
document 15 at the transfer station 28. Neither the original
document 15 nor the copy paper 16 moves during the copying and
printing process. After the complete image has been transferred to
the copypaper 16 from the magnetic tape 18 by the pressure transfer
roller 29, the paper is moved by a well known means, such as an
ejection finger 51, into a transport belt conveyor 52 to a radiant
fuser 17 and then into a collection tray 36. In recapitulation, a
carriage type magnetographic copier 10 is described which operates
as a real-time raster input scanner/raster output scanner
(RIS/ROS), wherein the CCD array 32 serves as the RIS and the
thin-film magnetic head array 32serves as the ROS. Because the
copier has a fixed platen 23, it is capable of either single
document or book (three dimensional) copying. Each element 37 of
the CCD array 32 is connected to an associated element in the
magnetic head array 22. Eacharray has 300 elements per inch for
high quality copying. The recording and printing process stations
are mounted on a movable carriage 13 through which a ribbon of
magnetic-tape 18 is threaded. The tape 18 is held
stationary during the copying mode,so that as the carriage 13
moves, the tape passes through the various process stations. The
CCD array 32 is attached by cable 14 to the carriage 13 for
accurate stitching or placement of the developed image segments of
the original document 15 on thecopy paper 16 by the pressure
transfer roller 29 at the transfer station 28. Otherwise, a
tolerance buildup between the start of scan by the CCD array 32 and
the start of recording on the magnetic tape 18 would cause the
segments transferred to the copypaper 16 to align improperly; that
is, the beginning and end of the segments would not match or line
up on the copy paper. To further assist in the alignment, holes are
punched in the tape 18 during manufacture thereof which are sensed
to exactlyinitiate the start of scan and concurrent start of
recording. The tolerance between segments or bands of image making
up the copy of the original document 15 is maintained by a code
strip 47 on the fixed portion of the copier frame. More elements
ofthe CCD array 32 and the correspondingly connected magnetic head
array elements are available than are necessary to produce a band
or segment of the original document 15. Accordingly, marks 47
accurately placed on the code strip 46 are sensed by the CCDarray
elements 37 when the CCD array 32 and carriage 13 are stepped by
movable housing 60 in the direction (Y direction) transverse to the
scanning direction (X direction) to produce the subsequent image
bands that make up the total image. An electroniccontroller 50,
such as a standard microprocessor, does not enable those CCD array
elements 37 which see the code strip marks. A stepper motor 48 is
used to move the CCD array 32 and carriage 13 via the movable
housing 60 over to the next segment of theoriginal document 15 to
be scanned. The combination of the code strip marks 47 read by the
CCD array elements 37 for scanning width control and the holes in
the magnetic tape 18 for start of scan control and the
interconnecting cable 14 between the CCDarray and the carriage
provides accurate, error-free segmental copying of an original
document. Such a magnetographic, carriage-type printer/copier 10
which records, develops and transfers the image on a ribbon of
magnetic tape 18 that does not move during the recording/printing
process, but is conveniently replenished when desired,provides a
high copy quality device with high quality maintainability in a
very cost effective manner. Many modifications and variations are
apparent from the foregoing description of the invention and all
such modifications and variations are intended to be within the
scope of the present invention.
Non Impact Printing (NIP)Posted on 22. May, 2010 by Denbagus in
Articles, Learning, Materi Kuliah Pada pembahasan kali ini akan
lebih ditekankan pada teknologi cetak modern (Non Impact Printing)
atau kata lainnya adalah teknologi cetak dengan acuan cetak tidak
tetap. Contoh paling sederhana yang dapat kita jumpai dalam
keseharian adalah printer inkjet yang kita gunakan. Dikatakan
sebagai teknologi cetak dengan acuan tidak tetap, karena sistem
cetaknya dikontrol langsung oleh image processor sebagai dasar
order cetakan yang langsung dicetak secara menyeluruh dalam acuan
cetak secara digital. Sebenarnya teknologi NIP ini sedikit
disinggung pada pembahasan sebelumnya di artikel Teknologi Cetak
Konvensional dan Teknologi Grafika. Secara teoritis, teknologi NIP
dibagi menjadi beberapa bagian. 1. Electrophotography Metode
mencetak tanpa menggunakan plate. Teknologi ini paling banyak
digunakan sampai sekarang serta mampu mencetak informasi yang
berbeda pada satu perintah cetak dengan multiwarna. Misalkan cetak
booklet dengan berbagai variasi isi dapat diproduksi dalam jumlah
terbatas. Misalkan menggunakan deskjet printer. 2. Ionography
Teknologi ini juga dikenal dengan pemindahan ion atau elektron.
Proses ionigraphy adalah mencetak gambar dengan menggunakan
cartridge elektron yang menghasilkan muatan negatif pada permukaan
nonkonduktif. Permukaan nonkonduktif terdiri dari sebuah drum
dengan dielektrik permukaan aluminium oksida yang menarik toner
magnetik. Ionography menggunakan muatan listrik statis untuk
menarik partikel toner dari drum ke substrat yang kemudian
dicetakkan. 3. Magnetography Magnetography mirip dengan teknologi
ionography, bedanya drum yang digunakan adalah magnetik. Gambar
elektronik dirubah menjadi muatan magnet pada drum. Kemudian
menarik toner yang mengandung partikel besi. Cetakan ini cocok
untuk mencetak warna-warna spot serta banyak digunakan untuk
mencetak barcode dan tiket. 4. Inkjet Sistem kerjanya adalah
cartridge menyemprotkan tinta pada permukaan kertas yang akan
dicetak berdasarkan informasi digital dari komputer. 5.
Thermography Mencetak dengan teknik pemanasan. Teknologi ini dibagi
menjadi thermal transfer, thermal dye sublimasi, dan transfer lilin
panas. 6. Photography Digunakan pada cetak foto konvensional pada
ruang gelap menggunakan kertas khusus yang peka cahaya. Berdasarkan
reproduksi informasinya, teknologi cetak NIP dibagi menjadi: 1.
Cetak Statis Sama dengan metode cetak konvensional, artinya
informasi yang sama dapat dicetak dalam jumlah banyak atau
berulang-ulang.
2. Cetak Dinamis Dapat mencetak informasi yang berbeda-beda pada
tiap lembarnya. Contoh cetak buku dengan isi yang berbeda tiap
halaman. Kelebihan menggunakan teknologi cetak NIP 1. Short Run
Printing Dapat mencetak dengan tiras atau jumlah di bawah 1000 exp,
full color, bahkan mencetak 1, 10 maupun jumlah tertentu. 2.
Personalisasi Unik, mampu mencetak dengan hasil yang berbeda
bergantung pemesan, meskipun dicetak secara bersamaan. 3. Printing
on Demand Mampu mencetak sesuai kebutuhan, dimana saja, kapan saja.
4. Distribution Printing Data digital dapat dicetak bersamaan
walaupun di tempat yang berbeda. 5. Variable Data Printing Data
yang akan dicetak dapat dirubah sewaktu-waktu, sehingga dapat
disesuikan dengan keinginan. Semoga bermanfaat.
Magnetography A plateless printing technology that is similar to
ionography except that the imaging drum is magnetic. The electronic
image is converted to a magnetic charge on the drum, which attracts
a toner containing iron particles. The toners are very opaque so
the process is best suited for spot colors rather than four-color
process printing, which requires transparent colors in order to
work effectively. The primary use for magnetography is for
applications that require barcoding, such as labels, business
forms, direct mail pieces, and tickets. The toners used for
magnetography are very opaque so they are well suited for barcode
printing, which requires a thick black colorant. The print
resolution is lower with magnetography than with some of the other
printing processes, but the printing speed is very fast. Press
speeds as high as 460 feet per minute can be attained.
Magnetography Magnetography is similar to ionography except that
the drum that is used is magnetic. The electronic image is
converted to a magnetic charge on the drum, which attracts a toner
containing iron particles. The toners are very opaque so the
process is best suited for spot colors rather than four color
process printing, which requires transparent colors in order to
work properly. Magnetography is used for applications, which
require variable imaging such as labels, business forms, direct
mail pieces, tickets, and barcoding, which is the main product
created with the process. Because the toners are so opaque, they
are well suited for barcode printing, which requires a thick black
colorant. The print resolution is lower with magnetography than
with some of the other processes, but the printing speed is very
fast. Press speeds as high as 460 feet per minute can be
attained.
Magnetographic
Oldest nonimpact printing process. Limited by the unavailability
of color toners. Involves creation of latent image on a magnetic
metal surface via the application of a magnetic field. This is
similar to the magnetic recording process used in magnetic tape and
disk systems. The magnetic surface is toned by a magnetic toner
consisting of pigmented fine iron particles.
The toner is transferred to the substrate in a manner similar to
electrophotographic printing. Units are sold by Nipson printing
systems.