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AR-651/810 PROCESS SECTION 10 - 6
10. 5. Surface Potential Sensor
10. 5. 1. General description
The surface potential sensor detects the surface potential of the photoconductive drum and controls it to
keep constant.
10. 5. 2. Construction
The surface potential is controlled by the following construction.
• Surface potential sensor
: Detecting the surface potential of the photoconductive drum
• Control section
: Controlling to keep the surface potential constant
• High-voltage transformer
: Supplying voltage to the main charger grid
PWA-F-LGC-340/341/342
IC58
IC27
IC56
IC18
Main charger grid
Surface potential sensor
Photo-
conductive
drum
High-voltage
transformer
Control
voltage
signal
D/A converter
Gate
array
Main CPU
BC-RAM
10. 5. 3. Control method
(1) Surface potential correction control
The adjusted output value of the main grid voltage in the BC-RAM is output to the main CPU.
Then control voltage data is output to the D/A converter from the main CPU through the gate
array.
The data is converted into the analog data by the D/A converter and then amplified.
The control voltage of the main output is output to the high-voltage transformer.
The high-voltage transformer outputs the main grid voltage proportionate to the control voltage.
The surface potential sensor detects the potential on the photoconductive drum and gives it
feedback to the main CPU.
The potential is compared to the control allowable level specified in the BC-RAM.
If the potential is out of the control allowable level, the main grid voltage to be changed is
calculated from the difference between the targeted value and detection value.
The output value of the main grid voltage is changed.
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