Canon imageRUNNER ADVANCE C5255, Service Manual, Page: 72 / 1443

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Technology > Laser Exposure System > Various Controls > Horizontal scanning synchronous control
Technology > Laser Exposure System > Various Controls > Horizontal scanning synchronous control
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Laser ON / OFF control
● Purpose
Laser light is turned ON / OFF according to the combination of laser control signals.
● Execution timing
After the power ON
● Control detail
DC Controller switches the 4 modes (forcible OFF mode, APC mode, Print mode and standby
mode) according to the laser control signal.
DC Controller (UN1)
Laser control signal
Video signal
Laser Driver
PCB
Laser beam
Scanner mirror
Mode Laser status Remark
Forcible OFF mode OFF Light intensity setting decided on APC is cleared.
APC mode ON Laser light intensity adjustment
Print mode ON / OFF Laser is emitted according to the video signal.
Standby mode OFF Host machine is in standby status.
Print
instruction
Image formation
ready timing
At 1st line (APC)
At 2nd line (APC)
At 3rd line (APC)
At 4th line (APC)
Mode
name
Standby
mode
Standby
mode
APC mode APC mode / Print mode
Forcible
OFF mode
LaserD
LaserC
LaserB
LaserA
PSTBY PSTBY PINTR PRINT LSTR
F-2-48
T-2-24
F-2-49
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Horizontal scanning synchronous control
● Purpose
This is to align the writing start position in horizontal scanning direction.
● Execution timing
Per 1 line
● Execution time
Approx. 7.5µs
● Control detail
1) DC Controller forcibly emits the laser diode on M-laser driver PCB by setting the laser
control signal of M -laser to APC mode. Also, DC controller forcibly emits the laser diode of
Bk laser driver PCB by setting the Bk laser control signal to APC mode.
2) Concerning the laser beam of M laser, there is a BD sensor (Y, M) on the scanning light
path and the laser bean is emitted to the BD sensor (Y, M). Regarding the laser beam of Bk
laser, there is a BD sensor (C, Bk) on the scanning light path and the laser beam is emitted
to the BD sensor (C, Bk) as well.
3) Two BD sensors detect the laser beam, create the BD signal (BD_YM, BD_CBk) and send
it to the DC controller.
4) DC Controller executes synchronous control based on this signal and sends the standard
BD signal to Main Controller as a horizontal scanning synchronous signal (BD) per 1 line.
5) When Main Controller receives those signals, it outputs the video signal (VDO_Y, VDO_
M, VOD_C, VDO_Bk) to DC Controller. As a result of this, the Laser Driver emits the laser
beam from the specified position for each line.