Canon iR C6800 Series, Service Manual

Page: 273 / 1404

Chapter 7
7-7
7.2 Image Formation Process
7.2.1
Image Formation Process
0003-1031
1. Latent Static Image Formation Block
This block consists of 3 steps, at the end of which a latent static image is formed on the photosensitive drum.
Step 1 (preexposure) [1]
In preparation for primary charging, the preexposure LED shines light on the surface of the photosensitive drum to
remove the residual charges from the surface, thus preventing uneven density.
Step 2 (primary charging) [2]
In preparation for laser exposure, the machine charges the surface of the photosensitive drum to an even, positive
potential. The machine uses charging method in which charges are indirectly applied to the photosensitive drum by
means of a charging wire.
Step 3 (laser exposure) [3]
When the surface of the photosensitive drum is scanned by a laser beam, the charges in the "light" areas become
neutralized, turning the areas into a latent static image. (The machine uses a system of laser exposure in which it
exposes nonimaging areas with laser light.)
2. Development Block
Step 4 (development) [4]
The machine deposits toner over the latent static image on the photosensitive drum, thus turning the latent image into
a visible image. The machine' s black toner is a magnetic 1component developer while its color toner is non
magnetic 2component developer; development of both makes is based on toner projection.
3. Transfer Block
In this block, the toner image on the surface of the photosensitive drum is moved to print paper by way of the ITB.
Step 5 (pretransfer charging) [5]
In full color mode, toner is deposited for all 4 colors on the ITB, with a difference in toner potential if left unattended.
A specific level of bias therefore is applied when black is developed for individual colors, thereby making sure that
the toner layers on the ITB are of an identical potential, thus increasing the efficiency of primary transfer.
Step 6 (primary transfer) [6]
A positive charge is applied from the back of the ITB to transfer the toner from the surface of the photosensitive drum
to the ITB. This process is repeated for all color (M, Y, C, Bk) in sequence.
Step 7 (secondary transfer) [7]
The toner on the ITB is moved to paper.
Step 8 (separation) [8]
Paper is separated from the ITB.
4. Fixing Block
Step 9 (fixing) [9]
The toner is permanently fused into the fibers of the paper by means of heat and pressure.
5. ITB Cleaning Block
Step 10 (ITB cleaning) [10]
The residual toner is removed from the ITB by way of cleaning the ITB.