Maintaining Primary/Transfer Corona Current Constant - Canon NP6317 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
C.

Maintaining Primary/Transfer Corona Current Constant

If the primary corona current is greater than the correct value due to changes in the environ-
ment, the level (analog) of the feedback signal to the differential amplifier circuit will increase and
the output from the differential amplifier circuit will fall. As a result, the primary/transfer corona
current will fall. Similarly, if the primary corona current is too low, it will be increased.
If the output side of the high-voltage transformer supplying the primary corona assembly
should be overloaded, the current will be limited to a certain maximum.
DC controler PCB
HVTON
CUR_LEV
GRDON
4-6
High-voltage transformer(HVT)
Variable
Differential
pulse
amplifier
width
oscillator
Q10
Limiter
circuit
24V
Comparator
Figure 4-301
COPYRIGHT © 1999 CANON INC.
24V
T3 drive
circuit
High-voltage
transformer
T1
U1
OVER
R5
Q10
Q8
T4
Q9
CANON NP6317 REV.0 APR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
Primary corona
assembly
Grid
Photosensitive
drum
Transfer corona
assembly