Browse Prior Art Database

CORONA CHARGING ELEMENT

IP.com Disclosure Number: IPCOM000023976D
Original Publication Date: 1979-Jun-30
Included in the Prior Art Database: 2004-Apr-01
Document File: 4 page(s) / 821K

Publishing Venue

Xerox Disclosure Journal

Abstract

This disclosure relates to corona discharge members used for depositing a charge on an adjacent surface and to a method of making corona discharge electrodes. One type of improved corona charging device is disclosed in United States Patent 4,086,650, wherein the corona discharge member comprises a thin wire coated (at least in the discharge area) with a dielectric material. In a preferred embodiment, this corona discharge member is positioned above a charge collecting surface carried on a conductive substrate held at a reference potential, and it is provided with means for coupling a corona generating voltage intermediate the conductive substrate and the wire of the corona discharge member A conductive shield adjacent the wire and a first biasing means for holding the shield at a potential different from the reference potential is also provided in the preferred embodiment Many of the prior art problems conventionally associated with charging devices have been overcome by the dielectric-coated thin wire of U S Patent 4,086,650 However, improved uniformity in currents and increased life of the dielectric-coated wire are desirable

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XEROX DISCLOSURE JOURNAL

CORONA CHARGING ELEMENT Proposed Classification 3udy P. Nagel U.S. CL 317/262 A Donald A. Seanor mt. Cl. H01g

This disclosure relates to corona discharge members used for depositing a charge on an adjacent surface and to a method of making corona discharge electrodes.

One type of improved corona charging device is disclosed in United States Patent 4,086,650, wherein the corona discharge member comprises a thin wire coated (at least in the discharge area) with a dielectric material. In a preferred embodiment, this corona discharge member is positioned above a charge collecting surface carried on a conductive substrate held at a reference potential, and it is provided with means for coupling a corona generating voltage intermediate the conductive substrate and the wire of the corona discharge member A conductive shield adjacent the wire and a first biasing means for holding the shield at a potential different from the reference potential is also provided in the preferred embodiment Many of the prior art problems conventionally associated with charging devices have been overcome by the dielectric-coated thin wire of U S Patent 4,086,650 However, improved uniformity in currents and increased life of the dielectric-coated wire are desirable

It has been found that corona charging devices having improved uniformity in currents and increased life of the dielectric-coated wire are possible by providing compression in the outer dielectric coating so that there is a residual compression in the dielectric material when the corona discharge member is placed in operation Thus, the improved corona discharge member of this disclosure is the type having an inner conductive electrode and an outer dielectric coating, the outer dielectric coating being under compression

One of the methods of providing compression in the outer dielectric coating so that there is a residual compression in the dielectric material is to make the corona discharge member by first applying stress to the inner conductive electrode, coating the inner conductive electrode with a dielectric coating capable of being compressed, said dielectric being in a softened or molten state, cooling the dielectric after it has been deposited upon the surface of the inner conductive electrode, and releasing the stress on the inner conductive electrode In this way, the inner conductive electrode contracts causing a compression of the outer dielectric coating An interfacial bond between the dielectric material and the inner conductive electrode results in the transfer of the ~load" (tension) from the inner conductive electrode to the dielectric coating material when the tension on the inner conductive electrode member is removed or released

~Compression" defines the mechanical properties of the outer dielectric coating wherein the coating is under a compressive stress Many well-known techniques may be used to impart the compression to the outer dielectric coating One

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