Canon 1000 Service Manual page 148

3. OPERATION AND TIMING
Figure 3-529 shows the circuit that controls the developing bias, and the circuit has the following
functions:
HVT3B
• Generates high voltage for AC bias
• Generates timing signals for AC bias generation
HVT3A
• Turns on and off the DC bias
• Generates AC bias
• Turns on and off the AC bias
• Controls the voltage for DC bias
The AC bias is generated and turned on/off as follows:
Transformer drive signal HVON=1 and developing AC bias enable signal HVACEN=1
The transformer is driven, and ±1kV is sent to the AC bias generation circuit.
Transformer for
+1kV
Transformer for -1kV
Timing signal generation
HVT3B
3-104
COPYRIGHT © 2001 CANON INC.
An AC bias is generated based on signals from the timing generation circuit.
When the AC bias output signal HVAC=1, the AC bias is applied to each
developing cylinder.
DC controller PCB
+1kV
-1kV
HVT3A (front)
Transformer for DC
AC bias
Voltage
generation
control circuit
circuit
AC bias
HVT3A (rear) (same as HVT3A (front))
Figure 3-529
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
For C
Voltage
control circuit
DC bias
For Bk
For Y
For M