Canon NP6317 Service Manual page 68

CHAPTER 4 IMAGE FORMATION SYSTEM
2. Controlling the DC Bias
The differential amplifier of Figure 4-402 operates when DCBC is 16V or below. (The range of
DCBC (analog) is 6 to 16V, as set by the copy density knob or the AE system.)
Differential amplifier goes ON.
Variable pulse-width oscillator goes ON.
DC high-voltage transformer goes ON.
The DC bias is applied to the developing cylinder.
The copy density knob changes the DC component of the developing bias as shown in Figure
4-401.
DC controller PCB
AE sensor
COPY DENSITY
knob
COPY DENSITY
lever
4-10
DCBC
DC component of
developing bias
COPY DENSITY lever scale
-100
-200
-300
-400
-500
DC bias
Figure 4-401 Changes in Development Bias
(DC component) by COPY DENSITY Knob
ACBON
DCBC
D/A
converter
Figure 4-402
COPYRIGHT © 1999 CANON INC.
6V to 16V
-500V to -0V
(5)
High-voltage transformer unit (HVT)
AC bias
T2 drive
switching
circuit
circuit
Differential
T3 drive
Variable
amplifier
circuit
pulse-width
oscillator
Q1
CANON NP6317 REV.0 APR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
24V
AC high-voltage
transformer T2
Photosensitive
drum
24V
Recoder
DC high-voltage
Static charge
transformer T3
eliminator
Developing
cyinder