Controlling The Intensity Of The Scanning Lamp; Outline - Canon CLC 1120 Service Manual

CHAPTER 3 EXPOSURE SYSTEM
III. CONTROLLING THE INTENSITY OF THE
SCANNING LAMP
A. Outline
Figure 3-301 shows the circuit that controls the intensity of the scanning lamp (LA2), and has
the following functions:
1. Turning on/off the scanning lamp.
2. Finds out whether the scanning lamp is on or not.
3. Controls the intensity of the scanning lamp (so as to keep the intensity to a specific level
against fluctuations in power voltage).
AC
power
supply
J2004 J450
LAERR
B4
LAON
B1
CPU PCB
LACNTL
B2
LAON-S*
B7
TIM-RST
B5
3-6
COPYRIGHT © 1999 CANON INC.
Rectifying
circuit
J9
FU1
4
1
24V
7
Lamp
regulator
10
drive circuit
9
24V
Error latch
circuit
4
6
Switching
circuit
PWM
Lamp
activation
Intensity detection
control circuit
circuit
Timer
circuit
Lamp regulator
Figure 3-301
CANON CLC1120/1130/1150 REV.0 MAR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Scanner
thermal
switch 1 (TP1)
J10
+
1
-
3
Scanning lamp
(LA2)
Scanner
thermal
switch 2 (TP6)