摘要 |
A scorotron and control therefor for charging and/or discharging a charge retentive surface such as a photoreceptor of the type utilized in the process of xerographic printing. The control connects the wire grid of the scorotron to ground via a plurality of zener diodes and a variable resistor. The voltage across the variable resistor is low compared to the total circuit voltage so that variations in the grid current result in small variations in grid voltage. The control provides for compensation for out of tolerance zener diodes as well as for photoreceptor aging manufacturing tolerances and temperature elevation. When the variable resistor is a light dependent resistor a light emitting diode contained in a bridge network also containing a thermistor provides for automatic compensation due to elevation in photoreceptor temperature when such temperature is sensed by the thermistor.
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