Canon imageRUNNER 2525 Series, Service Manual, Page: 60 / 402

The image data written to line memory is read out by the readout enable signal (RE_C, RE_D) generated basedon the BD synch
signal (BD_C, BD_D) for output to the laser driver PCB.
[6]
J8143 J8142
[3]
[3]
[2]
BD_C
RE_C
BD_D
[1]
RE_D
[5]
[4]
BD
s
ig
n
a
l
Main Controller PCB
No. Name No. Name
[1] Synchronous PCB [4] VDO
[2] Delay PCB [5] VDO signal process unit
[3] Line memory [6] Laser driver PCB
RE_C/D readout enable signal BD_C/D BD synch signal
NOTE:
Regarding BD signal formation
The BD sensor of the BD PCB receives light from laser C only, and is free of light from laser D, i.e., the BDsignal is generated
based on the light from laser C.
■ Controlling the Intensity of Laser Light
● APC Control
The machine monitors the laser light that is emitted to the built-in photo diode of laser diode and adjusts the laser to appropriate
intensity.
■ Controlling the Laser Scanner Motor
From when the laser scanner motor starts and the laser scanner motor reaches the number of target rotation to before image
formation starts, the machine controlsthe rotation speed by referring to the laser scanner motor rotation speed signal (FG signal).
During image formation, it controls the laser scanner motor rotationspeed based on BD signal.
Laser scanner motor rotation speed is controlled by speed-up signal (ACC signal) and speeddown signal (DEC signal).
2. Technical Explanation
50