Controlling The Developing Bias; Outline - Canon NP6320 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM
IV. CONTROLLING THE DEVELOPING BIAS
A.

Outline

The circuit shown in Figure 4-402 controls the developing bias. Its main functions are as
follows:
1. Switching AC component of the developing bias ON/OFF.
2. Regulating voltage of the DC component of the developing bias.
The copy density can be controlled by varying the voltage of the developing bias to suit the
following variables:
1. Settings of the copy density lever and recalibration dial
2. AE sensor output
The photosensitive drum gradually deteriorates with use, causing the potential (V
areas of the drum to increase and making the copy density to be incorrect for a given setting of the
copy density lever. To compensate for this, a copy density knob, which can be turned to raise the
DC bias by exactly the increace in V
4-8
COPYRIGHT © 1999 CANON INC.
, and thus to produce clear copies again.
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CANON NP6320 REV.0 DEC. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
) of light
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