Canon CP660 Service Manual page 130

CHAPTER 4 IMAGE FORMATION SYSTEM
3. ITD Cleaning Bias Generation Circuit
This circuit is controlled by four signals (Figure 4-610) from the DC controller PCB,
and generates the ITD cleaning DC (positive) bias, ITD cleaning DC (negative) bias, and
ITD cleaning AC bias for application to the ITD cleaning roller.
The ITD cleaning DC (positive) bias drive signal is used to turn on and off the DC
(positive) bias applied to the ITD cleaning roller, while the ITD cleaning DC (negative)
bias drive signal is used to turn on and off the DC (negative) bias applied to the ITD
cleaning roller.
The ITD cleaning AC bias drive signal, on the other hand, is used to switch the ITD
cleaning AC bias level to suit the conditions of the environment.
DC controller
PCB
4. Fixing Separation Bias Generation Circuit
This circuit is controlled by the fixing separation DC bias drive signal from the DC con-
troller PCB, and generates the fixing separation DC bias for application to the upper fix-
ing roller.
The voltage applied to the upper fixing roller is controlled by the fixing separation DC
bias drive signal. The level of the fixing separation DC bias, further, is kept to a specific
level.
4-32
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ITD cleaning DC (positive)
bias drive signal
ITD cleaning DC (negative)
bias signal
ITD cleaning AC bias
drive signal
ITD cleaning bias level
switch signal
Figure 4-610
ITD cleaning bias
generation circuit
CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
ITD cleaning roller
AC
+
DC (positive) or DC (negative)