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2. Turning On and Off the Primary Charging Roller Bias
The microprocessor (Q512) on the composite power supply PCB generates the
PDCPWN signal (pulse signal) under the control of the microprocessor master (Q301)
on the DC controller PCB. In response to the signal, the secondary side of the main
transformer (T101) turns on to apply a primary charging roller bias.
The main transformer (T101) is driven by the drive signal (MPWM) from the
microprocessor (Q512). The main transformer (T101) is also used as the high-voltage
transformer for the DC power supply and other loads.
3. Controlling the Primary Charging Roller Bias to a Constant Voltage
While a bias voltage is being applied to the primary charging roller, the
microprocessor (Q512) on the composite power supply PCB reads the PDCS signal
(analog signal) from the voltage detection circuit to control the PDCPWM signal so that
the output voltage is maintained at a specific level.
4. Switching the Primary Charging Roller Bias Application Voltage Level
The copier applies a cleaning bias to the transfer roller during initial rotation (INT),
while the scanner is moving in reverse (SCRV), and during last rotation, thereby cleaning
the transfer charging roller. (See p. 4-21.)
To enhance the result of cleaning by the cleaning bias and to prevent drum memory
caused by the cleaning bias, a cleaning primary charging roller bias is applied during
initial rotation and while the scanner is moving in reverse.
COPYRIGHT
©
1997 CANON INC. CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
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