Canon imageRUNNER ADVANCE C255 Series, Service Manual, Page: 58 / 987

5. The Main Controller PCB outputs video signals (Y_VDO, M_VDO, C_VOD, Bk_VDO) to the Y/M/C/Bk Laser Driver PCB
when it receives these signals. This enables the Y/M/C/Bk Laser Driver PCB to emit a laser beam from a fixed position for
each line.
NOTE:
As the BD signal is the horizontal scanning synchronous signal of the Bk color, the Bk color serves as each color's reference
for horizontal scanning.
<Y, M color> <C, Bk color>
Feeding
direction
Right standard Left standard
Y_VDO
M_VDO
C_VDO
Bk_VDO
Main Controller
PCB (UN81)
DC Controller
PCB (UN04)
Y Laser
M Laser
C Laser
Bk Laser
BD
Y/M/C/K
Laser Driver
PCB (UN05)
BD Sensor
Vertical Scanning Synchronization Control
Purpose
Aligns the write start position in the vertical scanning direction.
Execution timing
At printing
Control description
1. When the DC Controller PCB receives a print order, it detects an internal reference signal. Based on this signal, a vertical
scanning synchronous signal (ITOP) is generated and sent to the Main Controller PCB.
2. The Main Controller PCB generates a video signal in accordance with reception of the ITOP signal.
2. Technology
47