Vertical Scanning Synchronous Control - Canon imageRUNNER ADVANCE C3325 Series Service Manual

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Technical Explanation > Laser Exposure System > Controls > Vertical scanning synchronous control

■ Vertical scanning synchronous control

● Purpose
Aligns the write start position in the vertical scanning direction.
● Execution Timing
At each print
● Control description
1) When the DC Controller 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.
2) The Main Controller synchronizes with ITOP signal and generates video signals (Y_VDO,
M_VDO, C_VDO and Bk_VDO), and sends them to the Laser Scanner Unit.
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.
2 Technical Explanation > Laser Exposure System > Controls > Vertical scanning synchronous control
Laser Laser
Laser
Y/M Laser
ASIC
Driver APC signal
PCB(UN08)
DC Controller
Video signal
PCB(UN04)
CPU LAser ON/OFF signal
ITOP
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Laser
C/BkLaser
Driver
PCB(UN09)
Main Controller
PCB(UN05)
ASIC
F-2-40
2-29