Canon LBP6000 Series, Service Manual

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Chapter 2
2-5
In this control, the laser driver turns on/off the laser diode (LD) according to the laser control signal sent from the engine controller.
The following is the circuit diagram of the laser control.
F-2-5
The engine controller sends the laser control signal (CNT0, CNT1) for changing the operation mode of the laser to the logic circuit in the laser driver IC, as well as
the video signal (VD0, /VD0) for image formation. The laser driver IC executes laser control according to the combination of the CNT0, CNT1 signals.
The following is the combination of the laser control signal (CNT0, CNT1).
T-2-3
2.3.2.2 Horizontal Sync Control
0019-3464
LBP3100 / LBP3010B
This is the control to adjust the writing position in the image horizontal direction.
The following is the details of control procedure.
1) The engine controller controls the laser control signal during unblanking (*) to emit the laser diode (LD) forcibly.
2) The BD PCB exists on the scanning route of the laser beam, which is sent to the BD PCB.
3) The BD PCB detects this laser beam, creates BD input signal (/BDI) and sends it to the engine controller.
4) The engine controller creates horizontal sync signals (/BD) based on /BDI signal and sends the /BD signal to the main controller.
5) When /BD signal is input, the main controller outputs the video signal (VD0, /VD0) to the engine controller to adjust the writing position in image horizontal
direction.
Operation mode CNT0 CNT1 Remarks
Discharge L L The capacitor (C1) is discharged.
Data output H H At normal print
APC H L At using APC
Forced OFF L H At using image mask
Engine controller
Main controller
Laser driver PCB
Laser driver IC
BD Sensor
LD PD
C1
+3.3V
/BDI
+5V
CNT1
CNT0
VOD
/VOD
Sample hold
circuit
Drive
circuit
Comparator
Logic PCB
/BD