Determining The Optimum Laser Output; Laser Output Corrective Control; Laser Output Corrective Control - Canon GP605 Service Manual

D.

Determining the Optimum Laser Output

The laser output is determined so that the surface potential (light area potential VL) of the drum
at time of laser exposure will be identical to the target potential.
The relationship between the surface potential of the
drum (VL) and the laser output is determined based
on measurements taken several times.
VL3
VL2
VL1
Reference output
Potential
sensor
Developing
bias (DC)
Laser
Activation using
the reference output
determined at time of
shipment.
E.

Laser Output Corrective Control

If an optimum laser output cannot be selected after measuring the surface potential of the drum
several times, a corrective control sequence is started to determine the optimum laser output.
Measurement is continued by varying the
level of the laser output so as to attain
the target VL.
Target VL
Potential sensor
Developing bias
(DC)
Laser
Figure 6-207 Sequence of Operations (corrective control)
COPYRIGHT © 1999 CANON INC.
-10% -20%
Laser output
195˚C
WMUP WMUPR
Measurement
Measurement
(VL2)
(VL1)
Reference output -10%
Activation at an output 10%
lower than the reference
output.
Figure 6-206 Sequence of Operations
VL1
VL3
VL2
VL-NG
195˚C
WMUP WMUPR
-10% -20% Pw
Reference
output
Corrective control sequence
started
CANON GP605/605V REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 6 IMAGE FORMATION SYSTEM
If the target VL is obtained at
this measurement, control is
ended; otherwise, corrective
control is stated.
Measurement
Measurement
(target VL)
(VL3)
Pw
-20%
The laser output (P)
needed to attain the target
VL is determined.
If the measurement is identical to the
target VL, control is ended.
Measurements are taken as many
as 8 times; at times, an approximate
(to the target VL) may be used.
VL-NG VL1 VL2 VL3 VL8
Pw8
Pw1 Pw2 Pw3
The laser output needed to
attain the target VL is
determined.
200˚C
STBY
200˚C
STBY
6-9