Sub Scanning Synchronization Control; Laser Beam Intensity Control; Apc (Auto Power Control) Control - Canon imageRUNNER ADVANCE 8105 Series Service Manual

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Technology > Laser Exposure System > Controls > Laser Beam Intensity Control
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Sub Scanning Synchronization Control

This control is performed to adjust the writing position in the sub scanning direction.
<Execution timing>
When printing is started
<Control Description>
1) The DC Controller PCB generates synchronization signal in vertical scanning direction
(PVREQ) and sends to Main Controller PCB 2.
2) Main Controller PCB 2 receives PVREQ (synchronization signal in vertical scanning
direction) and sends the video signal to the DC Controller PCB.
3) The DC Controller PCB sends drive signal to the Laser Driver PCB to turn on the laser.
PVREQ
Image
ASIC
Image signal
Main
Controller
PCB 2
DC Controller
PCB
2 Technology > Laser Exposure System > Controls > Laser Beam Intensity Control
Laser Driver
PCB
F-2-54 F-2-54
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Laser Beam Intensity Control

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APC (Auto Power Control) Control

To keep constant laser light intensity per 8 beams (1BD basis)
<Execution timing>
When the laser is scanned (per line)
<Control Description>
1) The DC Controller PCB outputs laser control signal to the Laser Driver IC in the Laser
Driver PCB to set in APC mode.
2) The Laser Driver IC is set in APC mode and makes laser diodes (LD1 to LD8) to forcibly
emit in series.
3) The Laser Driver IC monitors laser diodes (LD1 to LD8) with the Photo Diode (PD) and
adjusts output of laser diode until the laser light intensity reaches a specified level.
Laser Driver PCB
LD1
LD2
LD3
LD4
PD
Laser Driver IC
LD5
LD6
LD7
LD8
2-40
Laser Control
Signal
DC Controller PCB
F-2-55 F-2-55
2-40