Canon GP200 Service Manual page 121

2. Turning ON and OFF the DC
Component of the Developing
Bias
The DC component of the developing bias is
turned ON and OFF by the DC bias ON/OFF sig-
nal (DCON) from the DC controller PCB.
The primary side of the main transformer
(T101) on the composite power supply PCB oper-
ates under the control of the CPU (Q605). When
the DCON signal is sent to the composite power
supply PCB, the CPU (Q605) generates the DC
bias control signal (BPWM), thereby turning ON
the secondary side of the main transformer
(T101) and applying the DC component of the
developing bias.
3. Controlling the DC Component of
the Developing Bias to a Specific
Voltage
The CPU (Q605) on the composite power sup-
ply PCB receives the application voltage from the
voltage detection circuit while the DC component
of the developing bias is being applied. This way,
the duty ratio of the BPWM signal is varied so as
to ensure that the DC output voltage is main-
tained to a specific value.
COPYRIGHT © 1996 CANON INC.
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4. Turning ON and OFF the AC
posite power supply PCB receives drive pulse sig-
nals from the CPU (Q605). When the AC drive
signal (ACON) is sent directly from the DC con-
troller PCB to the AC drive circuit, the AC compo-
nent generation transformer (T400) turns ON to
add an AC component to the DC component of
the developing bias.
5. Varying the DC Component of the
adjusted by varying the density correction curve
(DC component of the developing bias).
tion, the density is adjusted by fixing the density
correction curve and varying the bias DC compo-
nent to maintain good gradation.
changes in the drum, control is exerted at a spe-
cific timing (according to AGS measurement to
increase the developing bias).
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
3. OPERATIONS AND TIMING
Component of the Developing
Bias
The developing AC drive circuit on the com-
Application frequency: 1838 Hz
Application voltage: 800 Vp-p
Developing Bias
The density of the image during copying is
However, during printing under a printer func-
To correct image faults occurring because of
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