Controlling The Transfer Charging Roller Bias - Canon GP335 Service Manual

CHAPTER 6 IMAGE FORMATION SYSTEM
D. Controlling the Transfer Charging Roller Bias
1. Outline
The machine uses a charging roller for direct transfer. A DC bias is applied to the transfer
charging roller, and the mechanism is controlled for the following:
• DC bias constant voltage/constant current
• Application voltage level (correction; ATVC control)
• Output by operation mode
• Output by humidity sensor reading
AC power supply voltage input
Transfer charging output
enable signal(HVTEN*)
J103B J209B
Constant voltage/constant current
switch signal(HVTSEL*)
J103B J209B
Transfer output mode signal 1(HVTM2*)
J103B J209B
Transfer output mode signal 2(HVTM1*)
J103B J209B
Transfer output mode signal 3(HVTM0*)
J103B J209B
Serial communication
Transfer bias ON signal
Transfer bias level signal
J103A J209A
6-8
Composite power supply PCB
Transformer
High-voltage
drive signal
main transformer
Cleaning bias output signal
Voltage value
(ATVC measurement value)
Transfer bias ON signal
Transfer bias control signal
Measurement value
Figure 6-105
COPYRIGHT © 1999 CANON INC. CANON 405/335 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Cleaning bias
Output
control
Voltage
detection
High-voltage
transformer for
transfer charging
Current
Drive
detection
control
Current value
Photosensitive
+
drum
Transfer bias
Transfer
charging roller
Humidity
detection