Browse Prior Art Database

Dark Voltage Control System

IP.com Disclosure Number: IPCOM000082176D
Original Publication Date: 1974-Oct-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Ernst, LM: AUTHOR

Abstract

The system operates by holding a constant ratio between currents Ig and Ip (corona design parameters), while the grid voltage (voltage source V3) is maintained fixed to hold a constant dark on the photoconductor. The currents Ig and Ip are monitored directly via transistors T1, T2, and T3. Typically, resistors R1, R2 and R3 are the same value, and resistor R4 is the value of R1 divided by the fixed ratio. Thus, voltages developed across R3 and R4 are proportional to the currents Ip and Ig voltage across R3 proportional to Ip and voltage across R4 proportional to Ig. The voltage difference across R3 and R4 is used to control the voltage potential (variable voltage source V4) at the corona wire via the operational amplifier OP-AMP.

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Dark Voltage Control System

The system operates by holding a constant ratio between currents Ig and Ip (corona design parameters), while the grid voltage (voltage source V3) is maintained fixed to hold a constant dark on the photoconductor. The currents Ig and Ip are monitored directly via transistors T1, T2, and T3. Typically, resistors R1, R2 and R3 are the same value, and resistor R4 is the value of R1 divided by the fixed ratio. Thus, voltages developed across R3 and R4 are proportional to the currents Ip and Ig voltage across R3 proportional to Ip and voltage across R4 proportional to Ig. The voltage difference across R3 and R4 is used to control the voltage potential (variable voltage source V4) at the corona wire via the operational amplifier OP-AMP.

If the voltage on the photoconductor drops for some reason, the voltage across R3 increases with respect to the voltage across R4. The voltage at point A goes negative, increasing the voltage source V4. Thus, the total corona current increases and the voltage on the photoconductor is restored to its original level. If the photoconductor's voltage increases, the reverse occurs.

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