Apc Correction - Canon iR5000i Service Manual

CHAPTER 4 IMAGE FORMATION SYSTEM

2.5 APC Correction

The surface potential fluctuates in keeping with the increase/decrease in the laser output
caused by changes in laser temperature. To maintain the surface potential to a specific level,
the control value of the laser output is corrected.
The following shows the types of correction used for the laser output:
[1] Sheet-to-Sheet APC Control
Purpose: To maintain a specific level of surface potential without lowering productivity
when executing jobs in succession, the potential after laser output is measured between
sheets, ultimately correcting the control value of the laser output.
Timing: The control is executed during the first sheet-to-sheet interval each minute from the
start of continuous printing.
Potential measurement: The drum potential shows a discrepancy around the drum periphery
so that the average of potential levels is obtained. Based on the result, an appropriate correc-
tive value is obtained for the laser output. If measurement is not possible for some difficulty
(as in measuring between sheets), the attempt at measurement is continued for a further 1
min.
Main power
switch ON
Fixing assembly temperature
(end of fixing assembly warm-up)
Control panel power switch ON
[2] Initial Rotation APC Control
Purpose: To make up for the change in VL potential in the laser output caused by changes in
temperature after a while, the surface potential of the drum is measured, and the control
value of the laser output is corrected.
Timing: The control is executed during initial rotation for the first job 60 min after the end
of jobs.
Potential measurement: The drum potential shows a discrepancy around the drum periphery
so that the average of potential levels is obtained. Based on the result, an appropriate correc-
tive value is obtained for the laser output.
4-14 P
Potential Potential
control for control for
copying printing
COPYRIGHT © 2001 CANON INC.
1 min later
Start key
ON
Correction of
laser output
F04-205-01
2000 2000 2000 2000
Continuous printing
1 min later
Correction of
laser output
CANON iR5000i/iR6000i REV.0 JUNE 2001