Apc (Auto Power Control) - Canon imageRUNNER ADVANCE C255 Series Service Manual

4. The DC Controller PCB controls the Scanner Motor control signals (acceleration signals and deceleration signals) based on
the input timing of the BD signal to control the Scanner Motor rotation speed.

APC (Auto Power Control)

Purpose
Ensures constant laser beam light intensity for each line.
Execution timing
For each line (before writing the image)
Control description
1. The Main Controller PCB outputs the APC signal to the Laser Driver IC in the Y/M/C/Bk Laser Driver PCB.
2. The APC mode is set for the Laser Driver ICs of each Y/M/C/Bk Laser Driver PCB and the laser diode of each color is forcibly
activated. The photo diode (PD) monitors the laser diode (LD), and each Laser Driver IC adjusts the output of laser diode
until the laser light intensity reaches a specified level.
Main Controller
Acceleration signal
Deceleration signal
Scanner Motor rotation speed signal
BD
signal
DC Controller
PCB(UN04)
APC Signal
PCB (UN81)
BD
sensor
Bk Laser
Y/M/C/K
Laser Driver
C Laser
PCB (UN05)
M Laser
Y Laser
Laser Scanner Unit
Laser Scanner Unit
Y/M/C/K
Laser Driver
PCB (UN05)
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2. Technology
Scanner
Motor
Y Laser
LD
LD
PD
M Laser
LD
LD
PD
C Laser
LD
LD
PD
Bk Laser
LD
LD
PD