Canon imageRUNNER ADVANCE C3500 III Series, Service Manual, Page: 74 / 1252

3. The Laser Scanner Unit generates the laser drive signals based on the video signals. At this timing, the Laser Scanner Unit
emits laser beams to match the leading edge of image with that of paper.
NOTE:
If the process speed is slowed by the print mode, the cycle of the TOP signal in continuous printing is lengthened according
to the degree of slowing.
Laser
Main Controller
PCB(UN05)
DC Controller
PCB(UN049)
ASIC
CPU LAser ON/OFF signal
ITOP
Video signal
C/BkLaser
Driver
PCB(UN09)
APC signal
ASIC
Y/M Laser
Driver
PCB(UN08)
Laser
Laser
Laser
Image Mask Control
Purpose
Prevents soiling of the Secondary Transfer Outer Roller.
The image mask control is executed in both the horizontal and vertical scanning directions to control the laser beam not to be
emitted in non-image area.
Execution timing
At power-on, and at each print
Control description
Type Control description Mask Width
Horizontal scan-
ning The image mask in the horizontal scanning direction is executed based on the paper size
selected by the user. (Each color's BD signal is the reference) 2 mm
Vertical scanning The image mask in the vertical scanning direction is executed based on the paper size
selected by the user. (TOP signal is the reference)
2 mm
Scanner Motor Control
Purpose
Rotates the Scanner Motor at a specific speed.
Execution timing
At power-on, and at each print
Control description
Scanner Motor rotation speed is controlled by the Y/M Laser Driver PCB.
1. The Y/M Laser Driver PCB outputs Scanner Motor control signals (acceleration signal: ACC, deceleration signal: DEC) to
the Scanner Motor to rotate the Polygon Mirror.
2. Technology
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