Controlling The Primary Charging Roller Bias - Canon GP335 Service Manual

C. Controlling the Primary Charging Roller Bias
1. Outline
The machine uses a charging roller for direct charging. In addition to the DC bias, and AC bias
is applied to the primary charging roller to ensure stable charging. The control items include the
following:
• DC bias constant voltage
• AC bias constant current
• Application voltage level correction (APVC control)
• AC bias by environment (humidity) sensor and software counter reading
• DC bias by temperature sensor and software counter reading
AC power supply voltage input
Primary charging output enable
signalVPDC*)
J103B J209B
DC bias mode signalHVPH)
J103B J209B
Serial communication
AC bias ON signal
AC bias mode signal
AC/DC bias level signal
J103A J209A
COPYRIGHT © 1999 CANON INC. CANON 405/335 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Composite power supply PCB
High-voltage
Transformer main
transformer
drive signal
(for DC
component)
DC bias control signal
AC bias control signal
Current value
(APVC measurement value)
Measurement value
Figure 6-102
CHAPTER 6 IMAGE FORMATION SYSTEM
Voltage
Output
detection
control
DC bias voltage value
High-voltage
transformer for
Drive
primary
control
charging (for AC
component)
Measurement value
Primary charging
roller
DC bias
Photosensitive
AC bias
drum
Drum temperature
detection
Humidity detection
Current
detection
6-3