Controlling The Primary Charging Roller Bias - Canon iR2200 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM

2 Controlling the Primary Charging Roller Bias

2.1 Outline
Part 2>Chapter 5>4.4 "Controlling the Primary Charging Roller Bias"
The machine's primary charging is a direct charging method that uses a charging roller. In
addition to a DC bias, the charging roller is subjected to an AC bias to ensure stable charg-
ing.
The following items relate to the control of primary charging:
[1] Turning on/off the bias.
[2] Controlling the DC bias to a specific level of voltage.
[3] Controlling the AC bias to a specific level of current.
[4] Controlling the photosensitive drum resistance detection mechanism (APVC control).
[5] Controlling the AC bias based on the readings of the environment sensor (humidity) and
the soft counters.
[6] Controlling the DC bias based on the reading of the drum sensor (temperature).
24 VDC input from
main power supply
Primary charging
J301 output enable
signal
-B4
Serial communication
Print/standby mode signal
AC bias level signal
DC bias level signal
APVC measurement data
J301
-A3
-A1
J311-A2
J302-B14
The primary charging output enable signal is used as the AC pulse ON sig-
nal when the developing bias is being controlled.
Memo
4-4 P
COPYRIGHT © 2001 CANON INC.
Composite power supply PCB
+24V
J135
Transformer
drive signal
J136
-B9
DC bias
output ON
signal
DC bias
output
control signal
Current level
(APVC measure-
ment)
J136
Transformer
-A10
drive signal
-A12
AC bias output
control signal
Measurement result
Measurement result
F04-201-01
Primary DC
charging high-
voltage
transformer
(T502)
Voltage
Output
control detection
Current
control
Voltage level
Primary AC
charging high-
voltage trans
former
Drive
control
2000 2000 2000 2000 CANON iR2200/iR2800/iR3300 REV.0 MAR. 2001
charging roller
DC bias
output
J130-4
Photosensitive
AC bias
output
(temperature)
Current
detection
Primary
drum
Drum sensor
Environment
sensor
(humidity)