Canon CLC 1130, Service Manual

Page: 169 / 965

CHAPTER 6 IMAGE FORMATION SYSTEM
6-10
COPYRIGHT © 2002 CANON INC. CANON CLC1100/1130/1150/1160/1180 REV.2 FEB. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)
B. Controlling the Surface Potential of the Drum
1. Outline
The surface potential of the drum is measured for the following to determine the grid bias and
developing bias of the primary charging assembly:
• When the power switch is turned on and during initial multiple rotation following jam
removal. (drum surface potential control and dark area potential attenuation measurement)
• During last rotation for each copying run. (drum surface potential measurement only)
• During last rotation for every 2 hr. (drum surface potential measurement and dark area
potential attenuation measurement)
• When FUNCTION>DPC>DPC is executed in service mode. (drum surface potential control
and dark area potential attenuation measurement)
2. Measuring the Surface Potential of the Drum
As preparatory work taking place prior to the measurement of the machine's drum surface
potential, the photosensitive drum is charged to a level of Vg suited to the environment in question
during initial multiple rotation or during copying operation; specifically, the measurement of the
potential (VdI) is used to see if the charging assembly is operating normally. If an error is detected,
the machine will indicate E061-0020, -0030, or -0031 in its control panel. The measurement of
VdI, however, does not take place in service mode (FUNCTION>DPC>DPC).
The grid bias (Vg) of the primary charging assembly is set to the two levels of voltage shown in
Table 6-202, and the dark area potential when the laser is off (VD) and the light area potential when
the laser is on (VL) are measured by the potential sensor.
Using the VD/VL measurements and the grid bias (Vg), a graph like the one shown in Figure 6-
202 is prepared.
Table 6-202
Figure 6-202
Vgl Vg2
-500V -700V
Vg1 Vg2
Vd2
Vd1
VL2
VL1
Vd
VL
Drum surface
potential
Grid bias