Canon NP6251, Руководство по обслуживанию

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C. Controlling the Developing Bias/Roller Electrode
1. Outline
During copying, both AC bias and DC bias are applied to the developing cylinder.
The DC bias is a voltage which is the sum of 100 V and V
L2
measured by the potential
sensor before copying is started.
When the machine is not making copies, the degree of the DC bias is varied to suit
the surface potential of the drum to prevent adhesion of excess toner on the
photosensitive drum.
Figure 4-204
2. Control Timing
Table 4-201
,
,
,
,
,
,,
,,
,,
,,
,,
,,
Photosensitive
drum
Developing cylinder
V
DB
Dark area
Light area
Bias
V
DB
= V
L2
+ 100 [V]
Toner
COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
4-32
Bias
DC
component
AC component 1500 Vp-p,
2700 Hz
Voltage
+600V
+600V
V
L2
+100 [V]
Period
CNTR1, 2
INTR, AER, LSTR
during copying
SCFW, SCRV
during copying
Description
To prevent adhesion of excess toner on the
drum. (The surface potential varies
constantly, and is measured by the
potential sensor at all times.)
To prevent adhesion of excess toner on the
drum.
To prevent fogging of the background.
To execute toner projection.