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COPYRIGHT
©
2001 CANON INC. 2000 2000 2000 2000 CANON iR2200/iR2800/iR3300 REV.0 MAR. 2001
CHAPTER 4 IMAGE FORMATION SYSTEM
4-4 P
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).
F04-201-01
Memo
The primary charging output enable signal is used as the AC pulse ON sig-
nal when the developing bias is being controlled.
DC controller PCB
Primary charging
output enable
signal
DC bias
output
control signal
DC bias
output
AC bias
output
DC bias
output ON
signal
AC bias output
control signal
J301
-B4
J136
-B9
J135
J301
-A3
-A1
J136
-A10
-A12
24 VDC input from
main power supply
Composite power supply PCB
PW-CPU
Transformer
drive signal
Voltage level
J130-4
Transformer
drive signal
Photosensitive
drum
Serial communication
Print/standby mode signal
AC bias level signal
DC bias level signal
APVC measurement data
Primary AC
charging high-
voltage trans
former
Primary DC
charging high-
voltage
transformer
(T502)
Primary
charging roller
Drive
control
Current
detection
Output
control
Current
control
Voltage
detection
Current level
(APVC measure-
ment)
+24V
Drum sensor
(temperature)
Environment
sensor
(humidity)
Measurement result
Measurement result
J311-A2
J302-B14