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B. Controlling the Intensity of the Scanning Lamp
1. Outline
Figure 4-105 shows the circuit used to control the intensity of the scanning lamp, and
the circuit has the following functions:
q
Turning on and off the scanning lamp.
w
Controlling the intensity of the scanning lamp.
• Keeps the intensity to a specific level in spite of changes in the power supply
voltage.
• Controls the intensity to suit changes in the sensitivity of the drum.
• Controls the intensity to suit the setting of the Copy Density key.
• Controls the intensity (AE control) to suit the density of the original.
e
Checking the activation of the scanning lamp.
Figure 4-105
Q156
Micro-
processor
(master)
D/A
converter
Q159
Error
detection
circuit
12V
PWOFF
J111B
-6
J111B
-7
J111B
-8
CVRON
LINT
LAON
J503-4
J503-2
J503-2
Lamp activation
circuit
Power switch
SW1
Thermal
fuse
TP2
Scanning
lamp
J501-1
Arc circuit
Lamp regulator PCB
DC controller PCB
HIM1
Differential
amplification/
phase control
power voltage
circuit
J501-3
COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
4-6