Controlling The Developing Bias - Canon 1000 Service Manual

2. Controlling the Developing Bias

The developing bias applied to the developing cylinder is a combination of an AC bias and a DC bias. A
DC bias is generated by the transformer on the HVT3A, and an AC bias is generated by the HVT3A based on
±1 kV generated by the transformer on the HVT3B. (The AC bias is generated so that it assumes the wave
forms shown in Figure 3-528.) Both DC and AC biases are controlled by control signals from the DC
controller for application.
The DC bias to the stray toner collecting electrode is generated by the HVT3B and sent in response to
control signals.
Control signal
HVT3A (front)
Transformer for DC
Developing bias
Bk
COPYRIGHT © 2001 CANON INC.
HVT3B
C
Bk
Transformer for +1kV
+1kV
-1kV
Stray toner
collecting
C
electrode
0V
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
DC controller PCB
Transformer for -1kV
Transformer or
stray toner
collecting electrode
M
Figure 3-527
AC bias
Change by DC bias
Figure 3-528
3. OPERATION AND TIMING
M Y
HVT3A (rear)
+1kV
Transformer for DC
-1kV
Y
3-103