Browse Prior Art Database

REGULATION OF SELF-INDUCED DEVELOPER HOUSING BIAS VOLTAGE

IP.com Disclosure Number: IPCOM000025684D
Original Publication Date: 1987-Apr-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 105K

Publishing Venue

Xerox Disclosure Journal

Abstract

The regulation of self-biasing developer housings in electrophotographic imaging devices utilizing conductive magnetic brush development has been accomplished through the use of diodes, particularly Zener diodes which are reverse biased in series with the developer housing supply voltage. Two benefits for using this approach are the enablement of copy lighter and copy darker modes and the establishment of boundries for the floating range. A contingency of this control circuit is that the maximum voltage to which the housing will float is equal to the bias source voltage. Since the Zener diode voltage is additive to the required bias voltage, a higher than normal source voltage must be employed. This implies that adjustable voltage sources ar? required to incorporate this concept in a given xerographic imaging device. Since the source voltage may exceed 500 volts for copy lighter, the large voltage may pose design problems. Moreover, the necessity for adjustable source voltages hinders the use of floating bias in many copiers. These limitations may be addressed by the application of a Zener diode control employing both forward and reverse bias Zener diodes in series with the bias source voltage. This means that the source voltage acts as a center line about which the floating range can be established. The range above and the range below the center line are independently established by the choice of Zener

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 2

XEROX DISCLOSURE JOURNAL

REGULATION OF SELF- IND UC E D DEVELOPER HOUSING BIAS U.S. c1.35513 VOLTAGE Int. C1. G03g 15/00 Edward Savage
James Markovics

Proposed Classification

10'

The regulation of self-biasing developer housings in electrophotographic imaging devices utilizing conductive magnetic brush development has been accomplished through the use of diodes, particularly Zener diodes which are reverse biased in series with the developer housing supply voltage. Two benefits for using this approach are the enablement of copy lighter and copy darker modes and the establishment of boundries for the floating range. A contingency of this control circuit is that the maximum voltage to which the housing will float is equal to the bias source voltage. Since the Zener diode voltage is additive to the required bias voltage, a higher than normal source voltage must be employed. This implies that adjustable voltage sources ar? required to incorporate this concept in a given xerographic imaging device. Since the source voltage may exceed 500 volts for copy lighter, the large voltage may pose design problems. Moreover, the necessity for adjustable source voltages hinders the use of floating bias in many copiers. These limitations may be addressed by the application of a Zener diode control employing both forward and reverse bias Zener diodes in series with the bias source voltage. This means that the source voltage acts as a center line about which the floating range can be established. The range above and the range below the center line are independently established by the choice of Zener

Volume 12 Number 2 March/April 1987 89

[This page contains 1 picture or other non-text object]

Page 2 of 2

REGULATION OF SELF-INDUCED DEVELOPER HOUSING BIAS VOLTAGE (Cont'd)...