Canon Image Reader-A1, Service Manual

Page: 259 / 916

COPYRIGHT © 2001 CANON INC. 2000 2000 2000 2000 CANON iR5000i/iR6000i REV.0 JUNE 2001
CHAPTER 4 IMAGE FORMATION SYSTEM
4-19 P
3.2 Controlling Primary Charging
3.2.1 Outline
The primary charging control system serves the following functions:
1. Turning on/off the primary corona current.
2. Controlling the primary corona current to a specific level.
3. Controlling the grid bias to a specific level (fixed to 850 V by varistor).
The system used to control primary charging is constructed as follows:
F04-302-01
The following signals are used:
[1] primary charging leakage detection signal; ‘0’ upon detection of an excessively high or
low level of current.
[2] primary corona current control signal; the output of the primary corona current turns
ON when the voltage is about 3 V or higher or lower than 11 V; it turns OFF when the
level is about 12 V or higher.
[3] high-voltage remote signal; turns on/off the output of primary corona current.
DC controller PCB
High-v
oltage PCB
J102A J4502
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PR-LEAK-DETECT [1]
PR/TR-REMOTE [3]
Primary charging wire
Grid wire
T4506
J4507
1400µA
The primary charging bias
changes as follows in keeping
with the potential of HV-PR.
PR-CNT [2]
3V 11V 12V
600µA
HV-PR
Pr
imar
y corona
charging