Turning On And Off The Bias; Dc Bias; Ac Bias; Bias Constant Voltage/Constant Current Control - Canon iR1600 Service Manual

2.2 Turning On and Off the Bias

The primary charging roller bias is turned on and off as follows:

2.2.1 DC Bias

The DC bias is generated when the primary DC bias drive signal (PRDCFOT*) goes ON.
The level of the DC bias is controlled by the primary/developing DC bias output level signal
(DCPWM*).

2.2.2 AC Bias

The AC bias is applied when the primary AC bias drive signal (PRACFOT*) goes ON and
the primary AC bias ON/OFF signal (PRACON*) goes '0'.

2.3 Bias Constant Voltage/Constant Current Control

The output levels of the DC and AC biases applied to the primary charging roller are con-
trolled as follows:

2.3.1 DC Bias Constant Voltage Control

The output voltage level f the DC bias is detected by the bias voltage detection circuit,
and is fed back to the DC generation circuit by way of the comparison circuit. The ASIC on
the DC controller PCB varies the pulse width of the primary/developing DC bias output
level signal as needed to ensure that the voltage of the DC bias remains at a specific level.

2.3.2 AC Bias Constant Current Control

The output current level of the AC bias is detected by the primary AC bias current circuit,
and is fed back to the AC generation circuit by way of a comparison circuit. The AC genera-
tion circuit varies the amplitude of the primary AC bias ON/OFF signal as needed to ensure
that the current of the AC bias remains at a specific level.
COPYRIGHT© 2002 CANON INC. 2000 CANON iR1600/iR2000 REV.1 JAN. 2002
CHAPTER 5 IMAGE FORMATION SYSTEM
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