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HYBRID SCAVENGLESS DEVELOPMENT WITH STREAK FAILURE SENSING

IP.com Disclosure Number: IPCOM000027103D
Original Publication Date: 1995-Apr-30
Included in the Prior Art Database: 2004-Apr-07
Document File: 2 page(s) / 118K

Publishing Venue

Xerox Disclosure Journal

Abstract

A hybrid scavengless developer unit may be employed in an electrophotographic printing machine to develop the electrostatic latent image with toner particles. The developer unit includes a donor roll with fine wires positioned in the gap between the donor roll and photoconductive belt. Developer material is advanced on a magnetic brush roller to the donor roll. The donor roll is electrically biased relatively to the magnetic brush roller to attract toner particles thereto. The donor roll advances the toner particles to the development zone. At the development zone, the electrical field created by the alternating current applied to the wires causes the toner particles from the donor roll to form a toner powder cloud in the development zone. The toner powder cloud develops the latent image recorded on the photoconductive surface. Contaminants may be caught by the wire and produce dark streaks across the copies. A failure of this type usually clears itself after a small number of copies, i.e. about ten. This can produce unacceptable copies in the midst of a stack of acceptable copies. The customer, in many cases, would not be aware of the degraded copies, since they are buried in the stack. This problem may be solved by employing a scanning sensor. The scanning sensor is located after the developer housing before transfer. The sensor detects toner streaks on the photoconductive surface. The sensor scans the photoconductive surface in the interdocument regions so as not to be confused by the developed image. The scanning speed of the sensor is such that one inboard to outboard scan is accom lished in one interdocument zone. The interdocument zone

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XEROX DISCLOSURE JOURNAL

HYBRID SCAVENGLESS Proposed Classification DEVELOPMENT WITH STREAK U.S. C1.355/251 FAILURE SENSING
Int. Clark V. Lange C1. G03g 15/09

A hybrid scavengless developer unit may be employed in an electrophotographic printing machine to develop the electrostatic latent image with toner particles. The developer unit includes a donor roll with fine wires positioned in the gap between the donor roll and photoconductive belt. Developer material is advanced on a magnetic brush roller to the donor roll. The donor roll is electrically biased relatively to the magnetic brush roller to attract toner particles thereto. The donor roll advances the toner particles to the development zone. At the development zone, the electrical field created by the alternating current applied to the wires causes the toner particles from the donor roll to form a toner powder cloud in the development zone. The toner powder cloud develops the latent image recorded on the photoconductive surface. Contaminants may be caught by the wire and produce dark streaks across the copies. A failure of this type usually clears itself after a small number of copies, i.e. about ten. This can produce unacceptable copies in the midst of a stack of acceptable copies. The customer, in many cases, would not be aware of the degraded copies, since they are buried in the stack. This problem may be solved by employing a scanning sensor. The scanning sensor is located after the developer housing before transfer. The sensor detects toner streaks on the photoconductive surface. The sensor scans the photoconductive surface in the interdocument regions so as not to be confused by the developed image. The scanning speed of the sensor is such that one inboard to outboard scan is accom lished in one interdocument zone. The interdocument zone

define the sensor scan speed. For example, a 381 millimeter wide photoconductive belt running at 254 millimeters per second with a 50 millimeter interd...