Xerox Corporation

Ravi Sampath

Timothy Wayne Jacobs

John J Kopko

Clive R Daunton

John W Prebola

David T Zawadzki

An apparatus for charging a photoconductive surface to a substantially uniform potential in a printing machine having a cleaning station for cleaning the surface and an exposure station for exposing the surface to a light source includes a first mechanism for charging the surface to a substantially uniform potential of a first polarity after the surface is cleaned at the cleaning station. The apparatus further includes a second mechanism for charging the surface to a substantially uniform potential of a second polarity opposite to the first polarity after the surface is charged to the substantially uniform potential of the first polarity by the first charging mechanism and before the surface is exposed to the light source at the exposure station. Similarly, a method of charging a photoconductive surface to a substantially uniform potential in a printing machine having a cleaning station for cleaning the surface and an exposure station for exposing the surface to a light source, includes the steps of (1) charging the surface to a substantially uniform potential of a first polarity after the surface is cleaned at the cleaning station; and (2) charging the surface to a substantially uniform potential of a second polarity opposite to the first polarity after the first polarity charging step and before the surface is exposed to the light source at the exposure station.

Method and apparatus for charging a photoconductive surface to a uniform

A document background control system having a sensor in the optical path of a reproduction machine to sense the background of a document in the copy mode during the scanning of the document to adjust the illumination of the document and also includes a control to adjust the charging potential on the photoconductor in response to document background that is non-white.

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Fairport, NY, United States of America

Ravi Sampath