Voltage sensing in A.C. corotrons

Claim 1

In an electrostatographic device, having a photoreceptor member charged to a uniform voltage level prior to imagewise discharge thereof, and including at least a first corotron having a corona producing coronode driven with an A.C. voltage source supported therein, for neutralizing charge on a surface, and a conductive shield substantially surrounding the coronode, and open on a side adjacent to the photoreceptor surface, a surface potential measuring device comprising: a thin conductive wire electrode arranged parallel and across the photoreceptor surface, parallel to the coronode, and adjacent to the shield which derives a current proportional to the voltage on the photoreceptor surface.

Claim 9

A method for measuring voltage on a surface in an electrostatographic device, having a photoreceptor member charged to a uniform level of potential prior to imagewise discharge by exposure to light, and subsequent development of the image on said photoreceptor member with toner at a developing station by a developer arrangement applying a voltage level bias to a developer electrode arranged adjacent and across said photoreceptor member at said developing station, including at least a first corotron driven with an A.C. voltage source, for neutralizing charge on a surface, said corotron including a coronode supported parallel and across the photoreceptor surface between insulating end blocks and having a conductive shield substantially surrounding the coronode, and open on a side adjacent to the photoreceptor surface, including the steps of: placing a bare wire electrode in a position proximate and parallel to said A.C. driven coronode and said surface, adjacent to said shield; measuring a current in said electrode derived from its proximity to the coronode and photoconductive member; using said current as a proportional measure of voltage on the surface of said photoconductive member and controlling the voltage level bias to a developer electrode in accordance therewith.

Claim 10

A method for measuring voltage on a surface in an electrostatographic device, having a photoreceptor member charged to a uniform level of potential prior to imagewise discharge by exposure to light, and subsequent development of the image on said photoreceptor member with toner at a developing station by a developer arrangement applying a voltage level bias to a developer electrode arranged adjacent and across said photoreceptor member at said developing station, including at least a first corotron driven with an A.C. voltage source, for neutralizing charge on a surface, said corotron including a coronode supported parallel and across the photoreceptor surface between insulating end blocks and having a conductive shield substantially surrounding the coronode, and open on a side adjacent to the photoreceptor surface, including the steps of: placing a bare wire electrode in a position proximate and parallel to said A.C. driven coronode and said surface, adjacent to said shield; measuring a current in said electrode derived from its proximity to the coronode and photoconductive member; using said current as a proportional measure of voltage on the surface of said photoconductive member and controlling the voltage level bias to a developer electrode in accordance therewith.