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CONTROL OF STATIC CHARGE ON ELECTROGRAPHIC STYLUS HEADS

IP.com Disclosure Number: IPCOM000024497D
Original Publication Date: 1980-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 63K

Publishing Venue

Xerox Disclosure Journal

Abstract

In electrographic printers, it is common to use one or more metallic styli embedded in an insulating material as a printing "head". In such heads which are operated out of contact with a dielectric receiving sheet, the surface of the insulating material is usually configured so as to be coplanar with the active surfaces of the printing styli. During the operation of these printing heads, electrostatic charges deposit on the insulating surface adjacent to the styli ends, and the presence of these charges interferes with normal operation by distorting the discharge, thereby leading to "flaring" or spreading of the charge pattern formed on the nearby dielectric receiving surface.

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XEROX DISCLOSURE JOURNAL

CONTROL OF STATIC CHARGE ON ELECTROGRAPHIC STYLUS HEADS Donald C. Wilson

iMartin E. Banton
Chris to phe r Sne Ili ng

In electrographic printers, it is common to use one or more metallic styli embedded in an insulating material as a printing "head". In such heads which are operated out of contact with a dielectric receiving sheet, the surface of the insulating material is usually configured so as to be coplanar with the active surfaces of the printing styli. During the operation of these printing heads, electrostatic charges deposit on the insulating surface adjacent to the styli ends, and the presence of these charges interferes with normal operation by distorting the discharge, thereby leading to "flaring" or spreading of the charge pattern formed on the nearby dielectric receiving surface.

This problem can be largely overcome by limiting the charge accumulation on the face of the printing head, and this can be accomplished in three different ways: by removing the insulating material from the region adjacent to the active face of the styli, by providing conductive structures near to the styli, and by modifying the surface conductivity of the head so that charge may leak away during the time interval between imaging pulses applied to the styli. This surface conductivity may be obtained by the deposition of an electrically conductive material or a photoconductive material which is rendered conductive by exposure to light between imaging pu...