Canon NP6012 Service Manual page 71

F. Controlling the Developing/
Separation Static
Eliminator Bias
1. Outline
Figure 3-309 shows the circuit that con-
trols the developing/separation static elimi-
nator bias, and the circuit has the following
functions:
* turns on and off the DC component.
* turns on and off the AC component.
¢ controls the voltage level of the DC
bias according to type of developing
assembly.
* controls the voltage level of the DC
bias according to the copy density set-
tings.
The developing cylinder is given AC and
DC biases during copying operation.
While the photosensitive drum is rotat-
ing, except during development, about -500
V is applied to the developing cylinder
regardless of the position of the density
adjusting lever, thereby preventing adhesion
of excess toner to the surface of the photo-
sensitive drum.
AC power/,\ |
supply ©
~)
Photosensitive) Developing
drum cylinder
i | Static
[Amplifier!| | san
reefer +— eliminator
circuit :
DC controller PCB:
Microprocessor
AE signal
Cartridge color detection
signal
+
ABfntensity
sensor PCB
Copy density
Copy density
correction
signal
settings signal
Bo89
593
2b3e
g
Sensor Poa [een pane
Figure 3-309 -
3-26 COPYRIGHT © 1995 CANONINC.
CANON NPSO12/NPGOT2F /NP6212 REV. SEPT. 1995 PRINTED IN JAPAN (\MPRIME AU JAPON)