Overview/Configuration; Configuration; Print Process - Canon MF4690 - ImageCLASS B/W Laser Service Manual

6.1 Overview/Configuration

6.1.1 Configuration

The image forming system is the core part of this machine, and is composed of the cartridge, the transfer charging roller, the fixing assembly, etc.
When receiving the print command from the SCNT board, the DCNT board activates the main motor to rotate the photosensitive drum, the developing cylinder,
the primary charging roller, the transfer charging roller and the pressure roller.
The surface of the photosensitive drum is evenly charged negative by the primary charging roller, and the laser beam converted with the video signal (VDO, /VDO)
is reflected to the surface of the photosensitive drum to form the latent image by the laser diode.
The latent image formed on the photosensitive drum is turned visible with the toner on the developing cylinder and is transferred on the paper by the transfer charg-
ing roller. The transferred toner turns into the permanent image on the paper when the heat and pressure are applied there at the fixing assembly. The cleaner blade
removes the residual toner on the surface of the photosensitive drum, whose potential is made even by the primary charging roller to be ready for the formation of
the next latent image.

6.1.2 Print Process

The print process shows the basic operation process for image formation by the printer.
The print process of this machine has the main 5 blocks and 7 steps. The toner image is formed on papers by following the steps of each block.
The following is the outline of the blocks and steps of the print process.
1) Electrostatic latent image formation block
Electrostatic images are formed on the photosensitive drum.
Step1: Primary charging (Charges negative potential evenly on the surface of the photosensitive drum)
Step 2: Laser beam exposure (Forms electrostatic images on the photosensitive drum)
2) Developing block
Put the toner on the electrostatic latent image on the surface of the photosensitive drum to visualize
Step 3: Development
3) Transfer block
Fixing film area
PR1
TRS
DCNT board
DEV
Delivery
6. Fixing
Fixing block
7. Drum cleaning
5. Separation
Transfer block
4. Transfer
Pick-up
Laser beam
Laser /
scanner block
Video signal VDO /VDO
Print command
SCNT board
F-6-1
Drum cleaning
block
Electrostatic latent
image formation block
1. Primary charging
2. Laser beam exposure
3. Devel
opment
Developing block
Flow of paper
Direction of drum rotation
F-6-2
Chapter 6
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0016-1840
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