Xerox Corporation

Denis C Thomas

Satchidanand Mishra

Edward A Domm

Zoran D Popovic

Dennis J Prosser

Steven P Nonkes

Samy A Mesbah

A contactless process for detecting electrical patterns on the outer surface of a member comprising providing a member having a charge pattern on an outer surface, repetitively measuring the charge pattern on the outer surface of the member with an electrostatic voltmeter probe maintained at a substantially constant distance from the surface, the distance between the probe and the imaging member being slightly greater than the minimum distance at which Paschen breakdown will occur to form a parallel plate capacitor with a gas between the probe and the surface, the frequency of repetition being selected to cause all time dependent signals to fall out of phase by a predetermined amount, and averaging the out of phase time dependent signals over a sufficient number of measuring repetitions to eliminate the time dependent signals. In one embodiment, the contactless process detects surface potential charge patterns in an electrostatographic imaging member. Apparatus for carrying out these processes are also described.

Contactless system for detecting subtle surface potential charge patterns

The present invention is an apparatus for tuning or altering the charge potential limiting effect that a scorotron grid has upon an adjacent charge receiving surface. The scorotron charging apparatus utilizes corona producing means, spaced above the charge retentive surface, for emitting corona ions in response to a high voltage potential applied thereto, and a flexible grid, suspended between said corona producing means and the charge retentive surface in a nonplanar fashion, such that the spacing between said grid and the charge retentive surface is variable along at least one region of said grid.

Tunable scorotron for depositing uniform charge potential

The present invention is a charging apparatus capable of electrically tuning or altering, on a relatively local scale, the corona ion current passing between a corona producing device and a charge retentive surface. The charging apparatus, which may be either a corotron or a scorotron, is specifically adapted to apply a uniform charge to a charge retentive surface which characteristically exhibits non-uniform charging behavior. More specifically, the charging apparatus comprises corona producing devices, spaced apart from the charge retentive surface, for emitting a corona ion current, and device, responsive to a bias voltage, for locally altering the corona ion current passing between said corona producing device and the charge retentive surface. In the described embodiments, the ion current altering device includes segmented grids, segmented shields and segmented electrodes, all of which may be maintained at variable bias voltages to produce local variation in the ion current passing to the charge retentive surface.

Growing community of inventors

Hilton, NY, United States of America

Denis C Thomas