Canon CP660 Service Manual page 125

1. Primary Charging Bias Generation Circuit
This circuit is controlled by three signals (Figure 4-604) from the DC controller PCB,
and generates primary charging DC bias and primary charging AC bias for application to
the primary charging roller.
The primary charging AC bias is used to turn on and off the AC bias applied to the
primary charging roller, while the primary charging DC bias drive signal is used to turn
on and off the DC bias applied to the primary charging roller.
The primary charging bias level control signal is used to switch the levels of the pri-
mary charging DC bias for image areas.
DC controller
PCB
Note:
The primary charging DC bias level for image areas is varied in conjunction with the
developing DC bias of each color according to the density adjustment command from
1
the printer board*
1
* Reader controller PCB (when making prints with the reader unit installed).
COPYRIGHT © 1999 CANON INC.
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Primary charging DC bias drive signal
Primary charging AC bias drive signal
Primary charging bias level control signal
Figure 4-604
or based on the result of image density correction control (p. 4-21).
CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
Primary charging roller
Primary
charging bias
generation
AC
circuit
+
DC (negative)
4-27