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PROCESS RELATED SECTION
9 - 6
9.5
Drum Surface Potential Sensor Control Circuit
9.5.1
General description
The drum surface potential sensor measures the surface potential of the drum when the drum is
charged. Based on the measured value, this sensor controls the main charger grid bias voltage, and
thus can control the drum surface potential accurately.
9.5.2
Configuration
The configuration of this control circuit is shown below.
• Drum surface potential sensor:
Measures the drum surface potential.
• Control section (LGC board):
Calculates the main charger grid bias voltage to be applied when the image quality control is
performed, then controls the high-voltage transformer to adjust its bias voltage output.
• High-voltage transformer:
Generates and supplies the bias voltage of the main charger grid.
Fig. 9-4
Drum
Drum surface potential sensor
Main charger grid
IC58
Main CPU
IC27
NVRAM
IC56
ASIC
IC18
D/A
converter
High-voltage
transformer
Reference voltage: Vctr
Digital data
LGC board
Adjustment value
DRV0-1A