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CONTROL FOR A CORONA DISCHARGE DEVICE

IP.com Disclosure Number: IPCOM000025096D
Original Publication Date: 1983-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 117K

Publishing Venue

Xerox Disclosure Journal

Abstract

Control apparatus for a corona discharge device to be utilized in a xerographic reproduction machine. The control is characterized hy utilizing the shield or coronode voltage to derive signals which can be used for maintaining the photoconductive surface of the machine at a predeterimined voltage level. The voltage level on the shield or coronode is measured twice, once with the surface in its conducting state and with the surface in its non-conducting state. The difference between the two voltages is compared to a reference voltage to generate an output signal for controlling the voltage applied to either the shield or coronode depending upon which is being used.

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XEROX DISCLOSURE JOURNAL

CONTROL FOR A CORONA DISCHARGE DEVICE
Vittal U. Shenoy

80

Proposed Classification
U.S. C1. 355/3CH Int. CI. G03g 15/00

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FIG. 2

Volume 8 Number 4 July/August 1983 329

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CONTROL FOR A CORONA DISCHARGE DEVICE (Cont'd)

Control apparatus for a corona discharge device to be utilized in a xerographic reproduction machine. The control is characterized hy utilizing the shield or coronode voltage to derive signals which can be used for maintaining the photoconductive surface of the machine at a predeterimined voltage level. The voltage level on the shield or coronode is measured twice, once with the surface in its conducting state and with the surface in its non-conducting state. The difference between the two voltages is compared to a reference voltage to generate an output signal for controlling the voltage applied to either the shield or coronode depending upon which is being used.

As illustrated in Figure I, a dicorotron electrode comprising a wire 27 and insulating layer 28 is capacitively coupled to the secondary winding 80 of an AC power supply. The conductive shield 26 is operatively coupled to a DhotoreceDtor constant current power supply 82. The voltage applied to the conductive shield 26 by the constant current power supply 82 is fed to a subtracter device X4 which may include a conventional sample and hold component and an amplifier the former of which serves to sample and hold a voltage value, representing the voltage on the shield when the photoconductor 10 is non-conducting and then generate a signal representing the difference between that voltage and the voltage on the shield when the photoconductive surface is conducting. The difference between these two voltages is amplified and fed to a comparator 86. hileans 88 are provided for providing a reference voltage to the comparator 86 for comparison with the output of the subtracter 84. The output of the comparator is fed to the constant current power supply 82 for modifying the voltage applied to the conductive shield 26. In order to render t...