Canon IR5000 - iR B/W Laser, Service Manual

Page: 236 / 839

COPYRIGHT © 2000 CANON INC. 2000 2000 2000 2000 CANON iR5000/iR6000 REV.0 JULY 2000
CHAPTER 4 IMAGE FORMATION SYSTEM
4-23 P
3.4 Controlling the Pre-Transfer Charging
3.4.1 Outline
The system used for pre-transfer charging serves the following functions:
1. Controlling the DC bias to a specific level of current.
2. Controlling the AC bias to a specific level of voltage.
3. Controlling the output to suit the environment (fuzzy control).
The system used to control the pre-transfer charging is constructed as follows:
F04-304-01
The following signals are used:
[1] pre-transfer/separation charging leakage detection signal: ‘0’ when an excessively high
or low level of current is detected.
[2] pre-transfer charging control signal; the output of pre-transfer current turns ON when
the voltage is about 3 V or more and less than 11 V; it turns OFF when the voltage is
about 12 V or more.
[3] pre-transfer/separating charging remote signal; turns on/off the output of the pre-trans-
fer/separation current.
DC controller PCB
J510A
J4502
J4505
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
PT/SP-REMOTE [3]
PT/SP-LEAK-DETECT [1]
High-v
oltage PCB
Pre-transfer charging wire
1
2
3
-300µA
The level of current of the
pre-transfer bias varies as follows
in keeping with the potential of
PT-SP-CNT.
3V 11V12V
PT/SP-CNT
PT/SP-CNT [2]
High-v
oltage A
C
tr
ansf
or
mer
T4501
AC+DC
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