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10 May 1996
2. PROCESS CONTROL
2.1 LATENT IMAGE CONTROL
2.1.1 DRUM POTENTIAL SENSOR CALIBRATION
[A]
Main Board
The drum potential sensor [A] output is calibrated during the process control
self check.
The High Voltage Supply Board - B [B] has two relay contacts. Usually RA #1
grounds the drum. However, during the self check, the main CPU turns RA
#2 on and RA #1 off and applies the test voltage to the drum shaft [C]. In this
condition, the drum is isolated from the ground (floating).
By measuring the output of the drum potential sensor when –300 V (V
–600 V (V
) are applied to the drum, the sensor output is calibrated
600
automatically. (The machine can now determine the actual drum potential
from the potential sensor output.) Using -300 and -600 V results in a more
accurate calibration of the sensor, since the voltage applied to the supply
board is much closer to the actual value, which is –450 V for V
(Development bias) during the process control self check.
[C]
RA#1 and RA #2 are packed in RL1 on
RA #2
the High Voltage Supply Board – B.
–300 V
–600 V
RA #1
A172D507.wmf
Sensor Output
V600 (V
V300 (V
2-5
[B]
)
2
)
1
–300
PROCESS CONTROL
–600
Actual Voltage
A172D508.wmf
) or
300
B
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