Canon NP6218, FY8-13EX-000 service manual Controlling the Primary Charging Roller Bias, Mpwm

CHAPTER 4 IMAGE FORMATION SYSTEM

D. Controlling the Primary Charging Roller Bias

1. Outline

Figure 4-111 shows the circuit that controls the voltage applied to the primary charging roller; the circuit has the following functions:

•turns on and off the primary charging roller bias.

•controls the primary charging roller bias to a constant voltage.

•switches the application voltage level for the primary charging roller bias.

•switches the application voltage level for the primary charging roller bias.

•corrects the scanning lamp on voltage level

The main transformer (T101) is driven by the drive signal (MPWM) generated by the main transformer (T101).

The main transformer (T101), further, is used also as the high voltage transformer for the DC power supply and others in addition to providing the above functions.

Composite power supply PCB

Main transformer

T101

Rectifier circuit

	MPWM
Main transformer
(T101)
drive circuit

Current

detection

circuit

DC controller PCB

Filter circuit

Voltage

detection

circuit

PDCS

		Micro-
	processor
PDC-PWM
		Q512
PCS

Q301 (Master)

Micro- processor

Primary charging roller

Photosensitive drum

Figure 4-111

4-10 COPYRIGHT © 1997 CANON INC. CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)