User's Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
4–8
COPYRIGHT © 1998 CANON INC. CANON NP7161/NP7160 REV.0 AUG. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
Start key
ON
STBY STBYLSTRSCRVSCFWSCRVSCFWINTR
AER
Sequence
Developing DC bias
Developing AC bias
Voltage
control
Figure 4-110
2. Turning On/Off the Developing DC Bias
a. Turning On/Off the Developing DC Bias
• When DV_DC_DR is 0,
Oscillation control circuit turns off
DC high-voltage transformer turns off
The above condition deprives the developing cylinder of developing DC bias.
• When DV_DC_DR is 1,
Oscillation control circuit turns on
DC high-voltage transformer turns on
The above condition supplies the developing cylinder with developing DC bias.
b. Control Timing
As shown in Figure 4-110, a specific developing DC bias (-300 V) is applied to the
developing cylinder to prevent adhesion of excess toner to the photosensitive drum when copies
are not being made.