Canon imageRUNNER ADVANCE 4551i Service Manual page 99

DC Controller PCB
■ Main Scanning Synchronous Control
Main scanning synchronous control is operated at synchronous PCB based on BD synchronous signal.
Based on BD signal that is formed from A laser light detected by BD PCB, BD synchronous signal for each laser is formed inside
image PCB.
Image data written in the line memory is read out by the readable signal (RE_A, RE_B, RE_ C, RE_D) according to the 4 phase
differences formed inside the delayPCB based on the BD synchronous signal (BD_SYNCH) and is sent to the laser driver.
Because iR4225 is a 2 beam, the reading possibility signal becomes RE_C and RE_D.
NOTE:
Regarding BD signal formation
Not B laser but A laser only reaches BD sensor on BD PCB.
BD signal is formed based on A laser light.
J8143
Main Controller PCB2
J324
[6]
[1]
BD_SYNCH
RE_A
[2]
RE_B
[2]
RE_C
[2]
RE_D
[2]
[5]
J8142
[3]
[3]
[4]
[3]
[3]
86
2. Technology