UX-4000MU
FO-2950MU/C
d. High voltage unit control
The high voltage unit outputs the following voltages:
• Main charger voltage (DC-950V + AC600V peak to peak)
• Transfer charger voltage (DC+2100V + AC600V peak to peak)
• Developing bias voltage (DC-390V)
The following signals are outputted from the CPU (ASIC) to control the
above voltages.
• MCON
This signal is to turn on/off the main charger.
When this signal is outputted, Q7 is driven to the high impedance state.
Then Q9 conducts to drive transformer T2.
As a result, the main charger voltage is outputted to the secondary
side of the transformer.
• TC/BIASON
This signal is to turn on/off the transfer charger and the developing
bias voltage.
When this signal is outputted, Q3 is driven to the high impedance state.
Then Q5 is conducted to drive T1 to output the transfer charger volt-
age and developing bias voltage to the secondary side of the trans-
former.
• PWMSIN
This signal is to control the main charger voltage and the transfer
charger voltage. The PWM pulse of 295.28Hz is outputted.
This pulse waveform adds the AC component to the main charger volt-
age and the transfer charger voltage.
By changing the pulse duty of this signal, the main charger voltage
and the transfer charger voltage are controlled (during temperature
correction operation).
When the pulse duty of this signal is changed, the collector currents of
Q4 and Q8 are changed. Therefore, the base current of Q9 and the
drive current of transformer T2 are changed to change the main charger
voltage and the transfer charger voltage.
R29, R31, C19, and C20 from a filter circuit which dulls the waveform
of PWMSIN signal.
e. Electrical connection
TC
Q7
+24VP
+24VP
Q9
Q8
Q3
Q5
Q6
131
MC
CONTROL PWB
PW MSIN
PRINTER PWB
ON
5
12
129
115
CNPRT
3
14
ASIC
IC15
(LR38784)
CPU
(SH7041)
MC
TC/Bias ON
DC
Bias
Driver
IC1
T2
Transformer
T1
Transformer
Charger
roller
OPC
DRUM
Transfer roller
Separation electrode
Doctor
Developing
roller
Supply rollier
100V
Q4
Fig. 8
5 – 11
Содержание FO-2950M - B/W Laser - All-in-One
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