Image Formation System; Overview/Configuration; Construction; Printing Process - Canon LBP2900 series Service Manual

Chapter 2

2.4 IMAGE FORMATION SYSTEM

2.4.1 Overview/Configuration

2.4.1.1 Construction

The image formation system is the core of the machine, and consists of a cartridge, transfer charging roller, and fixing assembly.
When a print command arrives from the video controller, the engine controller drives the main motor in response, thus turning on the photosensitive drum,
developing cylinder, primary charging roller, transfer charging roller, and pressure roller.
Thereafter, the primary charging roller charges the surface of the photosensitive drum to a uniform negative potential; then, the machine scans a laser beam
that has been modulated by video signals (VDO, /VDO) across the surface of the photosensitive drum to form a latent image.
When a latent image has been formed on the surface of the photosensitive drum, the developing cylinder turns it into a visible image using toner, and then
the transfer charging roller moves it to print paper. The toner image is then fused permanently into the fibers of the print paper by the work of heat and
pressure inside the fixing assembly.
When all is done, the cleaning blade scrapes the residual toner off the surface of the photosensitive drum for collection as waste toner. The primary charging
roller once again charges the surface of the photosensitive drum to a uniform potential for the formation of the next image.
Fixing film unit
PR1
TRS
Engine controller
DEV
PCB
F-2-5

2.4.1.2 Printing Process

The machine's printing process consists of 5 major blocks and 7 sequential steps at the end of which a toner image is formed on print paper.
The following shows these blocks and steps with reference to a diagram indicating the relationship among individual steps:
2-6
Video signals (VDO, /VDO)
Intermediate
PCB
print
command
Laser/
scanner unit
Video controller
PCB
0008-0101
0008-0102