Service Manual
Operating Principles
2.1.3.6 Bias Control
This section describes the bias control.
A diagram of drum charge bias, image transfer bias, detach bias and developing bias control circuit
is shown in Figure 2-31. These bias generate from the +24
on high voltage supply board
These bias cut so that +24
is cut, while the interlock switch is off by case open
detected.
These bias are controlled by engine controller board (MC
The
and
signals are
image transfer
control. While
signal is to LOW, the image transfer roller is
active. And, while
signal is to LOW, the image transfer roller is charged to 1.2K
by high
voltage supply circuit. And while this signal is to HIGH, the image transfer roller is charged to
The
control to drum charge and DETACH SAW bias. While this signal is LOW,
the DETACH SAW is charged to
and the
drum is charged.
The imaging cartridge has charged screen between charge wire for
drum and
drum. The
charge screen is connected 310
diode. The charge screen control potential of
drum
surface to -310
The
signal control to developing bias. While this signal LOW, the developing roller is
charge.
The developing bias is changed by image density control volume. The developing bias is controlled
bias level (-205 V to -265
by this volume. The image density is controlled so that the
developing bias level.
24
Low
Voltage
Suppry Board
Interlock
Engine Controller
Board
24
High Voltage Supply
Board
:
●
●
●
. . . . . . . . . . . . . . . . . . . . . . .
.
●
FG
Figure 2-31. Bias Control Circuit
Image Transfer
Bias
1.2 or-O.6 K
●
Developing
Bias
-205 to -265
●
DETACH SAW Bias
-1
●
Drum Charge
r e c h a r g e
Screen
-310
Rev.
2-19
