Laser/Scanner System; Outline - Canon LBP 2460 - B/W Laser Printer Service Manual

CHAPTER 2
III. LASER/SCANNER SYSTEM
A. Outline
LLCONT
BD mirror
Mirror
When the DC controller receives a print signal (/PRNT) from the video controller, the DC
controller automatically stabilizes the intensity of the laser beam (automatic laser power control:
See page 2-27). The DC controller then receives the VIDEO signal (VDO) from the video
controller and sends it to the laser driver in the laser/scanner unit.
The laser driver turns the laser diode on and off according to the VDO signal and generates
the modulated laser beam only when the VIDEO DATA ENABLE signal (/LENBL) from the DC
controller is "L".
The modulated laser beam is aligned by a collimator lens and a cylindrical lens into a parallel
beam that strikes the scanning mirror that is rotating at a constant speed.
The beam reflected from the mirror is brought to a point of focus on the photosensitive drum
by the focusing lens located after the scanning mirror.
As the scanning mirror rotates at a constant speed, the beam is scanned across the drum at a
constant speed.
The drum also rotates at a constant speed allowing the laser beam to form an image on the
drum's surface.
2 - 26
External device
Video controller PCB
/BD VDO /VSYNC
DC controller
/LON VDO /LENBL PD /SCND /SCNRDY
Laser driver
Figure 2-3-1
/BDI
Cylindrical lens
Scanner motor
Scanning mirror
Focusing lens
BD PCB
Photosensitive drum