Controlling The Primary Charging Roller Bias; Outline - Canon NP6218 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
D. Controlling the Primary Charging Roller Bias

1. Outline

Figure 4-111 shows the circuit that controls the voltage applied to the primary
charging roller; the circuit has the following functions:
• turns on and off the primary charging roller bias.
• controls the primary charging roller bias to a constant voltage.
• switches the application voltage level for the primary charging roller bias.
• switches the application voltage level for the primary charging roller bias.
• corrects the scanning lamp on voltage level
The main transformer (T101) is driven by the drive signal (MPWM) generated by the
main transformer (T101).
The main transformer (T101), further, is used also as the high voltage transformer for
the DC power supply and others in addition to providing the above functions.
Composite power supply PCB
Main transformer
Main transformer
(T101)
drive circuit
DC controller PCB
4-10
T101
Rectifier circuit
MPWM
Current
detection
circuit
Figure 4-111
COPYRIGHT © 1997 CANON INC.
Filter circuit
Voltage
detection
circuit
Micro-
processor
PDC-PWM
Q512
PCS
Q301 (Master)
Micro-
processor
CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
Primary charging roller
Photosensitive drum