Canon NP6512 Service Manual page 59

b. Controlling the Intensity of the Scanning Lamp
The intensity of the lamp is controlled by the scanning lamp active voltage signal sent by the
DC controller PCB in serial.
The microprocessor (Q900) on the composite power supply PCB sends the intensity adjust-
ment signal (PWM_1KHz) in response to the scanning lamp active voltage signal. In turn, the
phase control circuit (HIC001) controls the voltage supplied to the scanning lamp.
The PWM_1KHz signal varies according to settings made in service mode. In relation to the
settings, the composite power supply PCB executes phase control so that variation will be between
10% and 90% in terms of pulse duty ratios and between 50.5 and 80 V for the 120V model (be-
tween 85.7 and 145.8 V for the 220/240V model) in terms of actual value.
The intensity during AE exposure remains a specific level, which is 56 V for the 120 V model
(108.5 V for the 220/240V model) in terms of actual values.
Related Service Mode
38 (LAMP_ADJ)
COPYRIGHT © 1999 CANON INC.
<PWM_1KHz signal>
Pulse duty= t/
Figure 3-202
Use it to adjust the intensity of the scanning lamp.
CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 3 EXPOSURE SYSTEM
t [msec]
ON
OFF
1
[msec]
1kHz
1
100 [%]
1k
3-11