Grid Bias Corrective Control; Determining The Optimum Laser Output - Canon iR7086 Series Service Manual

Chapter 7

7.4.4 Grid Bias Corrective Control

iR7105 / iR7095 / iR7086
If the optimum grid bias cannot be determined at the end of drum surface potential measurement, the machine starts its compensatory control sequence to determine
the bias.
Continues to take measurements while varying
the value of the grid bias so that it will be closer
to the target VD.
TargetVD
Potential sensor
Primary charging bias(DC)
Grid bas

7.4.5 Determining the Optimum Laser Output

iR7105 / iR7095 / iR7086
The machine determines the optimum laser output so that the drum surface potential (light area potential VL) is identical to the target potential.
Potential sensor
Developing bias(DC)
Laser
Turn on the lamp at 80% of the reference
output determined at time of shipment.
7-6
VD1
VD3
VD2
VD-NG
193
WMUP WMUPR
650 V
550 V
or
750 V
Potential control
sequence started
The machine takes measurements multiple times
to determine the relationship between the drum
surface potential (VL) and the laser output.
VL3
VL2
VL1
60% 80% 100%
Laser output
195
WMUP
WMUPR
Measurement(VL2) Measurement(VL1orVL3) Measurement (target VL)
80%
After measuring VL2, measures VL3 if VL2
is grater than the target VL; if smaller,
measures VL1.
When the measurement is identical to the target VD,
ends the control. The machine executes measurement a
maximum of 8 times, possibly using an approximate
target VD.
VD-NG VD1 VD2 VD3
Vg
Vg1 Vg2 Vg3 Vg8
Compensatory control
sequence started
F-7-8
If this measurement brings about
the target VL, ends the control;
otherwise, starts compensatory control.
Pw
60% or 100%
F-7-9
198
STBY
VD8
A grid bias (Vg) needed to attain the
target VD is determined.
198
STBY
Determines the laser output (P)
needed to attain the target VL.
0010-8042
0010-8043