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COPYRIGHT
©
1999 CANON INC. CANON imageRUNNER 600 REV.1 JAN. 2000 PRINTED IN U.S.A.
6-9
CHAPTER 6 IMAGE FORMATION SYSTEM
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.
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.
Figure 6-207 Sequence of Operations (corrective control)
WMUPR
WMUP
STBY
195˚C
200˚C
Potential
sensor
Laser
Reference output
Reference output -10%
-10%
-20%
-20%
Measurement
(VL1)
Measurement
(VL2)
Measurement
(VL3)
Pw
VL1
VL2
VL3
Laser output
The relationship between the surface potential of the
drum (VL) and the laser output is determined based
on measurements taken several times.
If the target VL is obtained at
this measurement, control is
ended; otherwise, corrective
control is stated.
Activation using
the reference output
determined at time of
shipment.
Activation at an output 10%
lower than the reference
output.
The laser output (P)
needed to attain the target
VL is determined.
Developing
bias (DC)
Measurement
(target VL)
WMUPR
WMUP
STBY
195˚C
200˚C
Potential sensor
Developing bias
(DC)
Laser
-10% -20%
Pw Pw1 Pw2 Pw3
Pw8
VL1
VL1 VL2 VL3 VL8
VL-NG
VL-NG
VL2
VL3
Target VL
Measurement is continued by varying the
level of the laser output so as to attain
the target VL.
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.
Corrective control sequence
started
The laser output needed to
attain the target VL is
determined.
Reference
output
Figure 6-206 Sequence of Operations