Laser/Scanner System; Outline - Canon LBP-1120 Service Manual

III. LASER/SCANNER SYSTEM
A. Outline
The printer contains a laser driver (IC801) on its laser driver PCB.
The microcomputer (CPU : IC201) on the engine controller sends the LASER CONTROL signals (CNT0, CNT1) to
the IC801. Meanwhile, the interface controller sends the VIDEO signals (/VDO, VDO) to the IC801 through the
engine controller.
The IC801 emits laser diode based on these signals sent from the engine controller and interface controller.
The laser beam emitted form the laser diode passes though the collimator lens and cylindrical lens, and then strikes
the four-faced scanning mirror rotating at a constant speed. Then, the beam reflects off the scanning mirror, passes
through the focusing lens, and strikes the reflective mirror. The beam reflects off the reflective mirror and finally, scans
onto the photosensitive drum.
The photosensitive drum rotates at a constant speed, and at the same time, the laser beam scans across the drum
surface at a constant speed. This allows the laser beam to form a latent image on the drum surface.
Interface controller PCB
/BD
Engine controller PCB
/DEC
/ACC
Four-faced
scanning
mirror
Scanner motor
Focusing lens
Reflective mirror
Photosensitive drum
Figure 2-3-1
/VDO,VDO
CNT1
/BDI
CNT0
Cylindrical
lens
Laser
unit
BD sensor
CHAPTER 2
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