Canon 1000 Service Manual page 150

3. OPERATION AND TIMING
3. Controlling the DC Bias for Stray Toner Collection
Figure 3-531 shows the circuit that controls the DC bias for stray toner collection, and the circuit has the
following functions:
• Turns on and off the DC bias for stray toner collection.
• Executes constant current control.
The stray toner collection DB bias is turned on and off by the stray toner collection DC bias drive signal
(HVSRD) as follows:
HVSRD=1
The variable width pulse oscillator circuit turns ON, and pulse output is sent to the transformer.
The transformer is driven.
The output of the stray toner collection DC bias is monitored with reference to its current value, and the
data is fed back to the variable width pulse oscillator circuit. This feedback ensures a constant level of DC
bias.
Variable width pulse
oscillator circuit
3-106
COPYRIGHT © 2001 CANON INC.
A DC bias is applied to the stray toner collection electrode.
DC controller PCB
24V
Transformer
Figure 3-531
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
HVT3
DC bias
Current
detection
circuit
To stray toner collection electrode