Charge

Charge Laser Expose

Transfer

CleanDevelopment

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DevelopedTonerImage

Charged Background Area

Discharged Image Area

Photoreceptor

Typical Xerographic Print Engine

Fuse

2) Exposing 1) Charging

3) Developing 4) Transferring

5) Cleaning

Fusing

OutputPhotoreceptor

Imaging

The Xerographic Process

Xerographic Process1) Charging

Charging prepares the Photoreceptor. In charging, a uniform electric charge is deposited on the surface of the Photoreceptor. There are two types of charging technology: contact and non-contact. Each has pros and cons that need to be considered for each engine type and market.

ImagingImaging converts the computer data or the original into an optically projected image or digitally halftoned representation of the image.

2) ExposingThe exposing process causes the level of electrical charge on the photoreceptor surface to change to correspond with the desired image. After exposure, the electrical charge on the photoreceptor surface which represents the lines, letters, or other forms differs from the charge in the non-image areas. Exposure is mostly done using laser beam, light emitting doide (LED) in today’s machines. Older engines used a projected image using light and various lens.

3) DevelopingDeveloping deposits particles of Toner (dry ink) on the Photoreceptor. This is accomplished by first applying a charge to the toner particles. Due to this charge, toner only clings to the areas of the photoreceptor which correspond to the image. After development, a toner image is visible on the photoreceptor. There are many different development technologies used in today’s powder marking engines.

4) TransferringThe purpose of transfer is to bring the paper into contact with the photoreceptor so that the toner image can be transferred to a substrate. The transfer step involves applying a charge to the substrate so that toner is electrostatically removed from the photoreceptor surface and attracted to the substrate. After transferring, some residual toner remains on the surface of the photoreceptor. In some architectures, two transfer steps are needed to get toner from an intermediate belt or drum to the paper. Others transfer toner directly to the paper, without an intermediate.

FusingThe Fusing step heats the toner particles, causing the particles to flow together as they melt onto the surface of the paper. After fusing, theimage sticks permanently to the paper.

5) CleaningThe Cleaning step (sometimes includes Discharge) removes the residual charge of the image that was left on the photoreceptor (P/R) after transfer. Discharge can be accomplished by applying light or a neutralizing charge to the photoreceptor so that the residual toner no longer clings to the photoreceptor. Cleaning then mechanically removes the residual toner from the P/R. This is usually accomplished using brushes, blades, rolls, or some combination of the three.

Once the Photoreceptor is clean, we are ready to repeat the overall process.

Example Architectures

Tandem Color using Intermediate Transfer Architecture (above and below)Multipass/Cyclic Architecture

Hybrid Scavenge lessDevelopment

ROS

ROS

ROS

ROS

Cleaner

FuserTransferdicorotrons

Photoreceptor

Transfer assist blade

AcousticTransferAssist

Precleandicorotron

DC&AC Charge scorotrons

Pre-transf erdiscorotron

Hybrid Scavenge lessDevelopment

ROSROS

ROSROS

ROSROS

ROS

Cleaner

FuserFuserTransferdicorotrons

Photoreceptor

Transfer assist blade

AcousticTransferAssist

Precleandicorotron

DC&AC Charge scorotrons

Pre-transf erdiscorotron

Image on Image Architecture