Laser Driver Pcb; Outline - Canon GP405 Service Manual

III. LASER DRIVER PCB
A. Outline
Figure 5-300 shows the laser driver PCB, which drives the laser semiconductor using control
signals and the image signals from the image processor PCB. The circuit has the following
functions:
1. Driving the laser semiconductor
2. Stabilizing the laser intensity (APC control)
3. Switching laser activation mode
4. Switching laser output
The image signals from the image processor are written in the line memory in conjunction with
the sync signals generated for internal use on the laser driver PCB. The laser drive signals are
generated based on these image signals to drive the laser semiconductor.
BD detection
PCB
Horizontal sync clock
signal
J717B
Image signal
J717A
8
Write enable signal (VDR)
J717B
Laser activation mode switch signal
(SDATX: serial data)
J717B
Laser output switch signal
(SDATX: serial data)
J717B
Laser activation enable
signal (LDE)
J717B
COPYRIGHT © 1999 CANON INC. CANON 405/335 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)

Laser driver PCB

Q506
Clock signal
generation for
J500B
synchronization
Q504
J500A
Line memory
J500B
J500B
Laser power signal
J500B
5V
Laser semiconductor
D501
J500B
Figure 5-300
CHAPTER 5 LASER EXPOSURE SYSTEM
Image signal
Q509
Laser power control
PD
Q508
Sample voltage
Q507
Laser drive
signal
generation
APC control
Laser drive control
5-5