Determining The Laser Output - Canon iR5000 Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM

2.3 Determining the Laser Output

To measure the light area potential (VL1) after the power switch is turned on, the poten-
tial based on the previous laser output (LP0) is let to flow, and the surface potential of the
drum is measured by the potential sensor.
The DC controller PCB compares the surface potential of the drum against the target po-
tential; if the measured potential is ±6 V or higher, the potential of the laser output is cor-
rected, and the potential is corrected once again.
The potential is measured as many as eight times, and the laser output is corrected as
many as eight times. In addition, the developing bias for light area (VL2) is measured under
the corrective conditions used to determine the laser output (LP) needed for target potential.
Fixing assembly
temperature 195˚C
Potential sensor
Developing bias
(DC)
Laser
4-12 P
Target VL1
WMUP
VL1
LP0
Potential control
sequence start
F04-203-01
COPYRIGHT © 2000 CANON INC.
VL1
VL1
+6V
-6V
VL1
VL1
Previous potential
WMUPR
VL1 VL1 VL1 VL1 TargetVL1
LP0 LP0 LP0 LP0
Correction control
sequence start
2000 2000 2000 2000
200˚C
STBY
VL2
LP
CANON iR5000/iR6000 REV.0 JULY 2000