Xerox Corporation

Lawrence M Hart

Oscar G Hauser

Robert W Anderson

Frank C Genovese

Steven B Bolte

Raymond W Stover

W Keith Gilliland

John Maksymiak

Xu H Feng

Charles Nesta

Ding Ya-Jun

A method and apparatus for providing a novel dynamic developer bias control system adapted to determine an optimal developer bias during the processing of the lead edge of an input document. Loss of image density for images on the lead edge of a document is minimized by varying the developer bias relative to variations in an optical sensor voltage signal. In addition, background development in the body of the copy sheet is further prevented by maintaining a developer bias at an elevated level in response to a determination that the lamp voltage exceeds a maximum level and the optical sensor signal is less than a predetermined target value.

Dynamic developer bias control for use in an electrostatographic

In an ionographic device projecting a modulated stream of ions in imagewise fashion towards a moving imaging surface, including an ion printing head having an ion chamber supporting a coronode held at a voltage V.sub.C to produce ions for deposit on an imaging surface and a modulation channel extending from the ion chamber towards the imaging surface through which a stream of ions is directed for imagewise modulation by a plurality of modulation electrodes, electric field distribution within the ion chamber is controlled by selectively varying voltages along the surface regions of the ion chamber to different voltage levels, in an arrangement causing focusing of ion density in the area of the ion chamber adjacent to the modulation channel. An increased ion density in the area of the ion chamber adjacent to the modulation channel assists in providing an increased corona current at the output of the device.

Method and apparatus for increasing corona efficiency in an ionographic

In an ionographic device projecting a stream of ions towards a moving imaging surface, modulated in imagewise fashion, one or more control electrodes may be arranged adjacent to the path of the ion stream and between the source of the modulated ion stream and the imaging surface, biased with a voltage preventing previously deposited charge from perturbing the trajectory of subsequently projected ions to limit the amount of ion beam deflection caused by the presence of electrostatic charge patterns on the electroreceptor.

Method and apparatus for controlling ion trajectory perturbations in

Electrostatographic apparatus comprising an imaging surface with an electrostatic transfer evice to transfer toner particles to a receiving sheet and an apparatus to detack the sheet from the drum comprising a plurality of conductive fibers extending cross the rear side of the receiving sheet which are spaced from the sheet and have applied thereto a low voltage direct current potential of a polarity opposite the polarity on the receiving sheet and sufficient to cause air breakdown between the receiving sheet and the end of the fibers to provie a controlled neutralization of charge on the receiving sheet to a potential level above zero and thereby separate the receiving sheet from the drum by virtue of its own weight and beam strength.

Detacking apparatus

An electrostatic copying or printing machine having a developing system including a developer housing with a top access opening and a lower sump for storing a quantity of developer, a magnetic brush type developing roll for developing latent electrostatic images on the machine photoconductive member, a paddle wheel having a succession of paddles about the circumference therefor for loading developer from the sump onto the developing roll, and to facilitate clearing developer from the sump preparatory to inserting a fresh developer developer charge, at least one of the paddles being provided with a magnet substantially coextensive therewith for drawing developer from the developer sump to the paddle when the level of developer in the developer sump falls below the path of movement of the paddles, and a removable pick off baffle attachable to the developer housing adjacent the access opening when the sump is to be cleared of developer, the pick off baffle when in place intercepting developer carried by the developing roll and discharging the developer to a point exterior of the developer housing.

Apparatus and method for removing developer from the sump of an

An erase device for removing residual charges from the photoreceptor of a xerographic type reproduction machine or printer preparatory to recharging, comprising, an elongated rectangular light conducting bar or fiber adapted for disposition with one side thereof in preset spaced relation to the photoreceptor surface; a light impervious cover about the remaining sides of the fiber to prevent escape of light from the interior thereof; an illumination cavity at one end of the fiber; a lamp in the cavity in operative relationship within the fiber end, the lamp and cavity cooperating so that light is discharged by the lamp into the fiber for transmittal axially within the fiber toward the fiber opposite end, portions of the light in the interior of the fiber escaping through the fiber one side to impinge upon the photoreceptor surface and discharge the photoreceptor; the fiber one side being roughened so that the light exit area progressively increases in proportion to the distance from the lamp, the roughened portion enabling the discharge of light through the fiber one side and providing a proportionally increasing light emitting surface in accommodation of the fall off in light intensity as the distance from the lamp increases. In a second embodiment, the fiber is semi-circular in cross section, the rounded portion of the fiber being covered with a cladding material to prevent the escape of light therefrom while permitting the discharge of light from the uncovered flat portion of the fiber, the fiber being positionable with the flat portion thereof in preset spaced relation to the photoreceptor surface, the surface area of the fiber flat portion being roughened to enable the discharge of light from the fiber and progressively increasing in proportion to the distance from the lamp to accommodate fall off in the intensity of the light discharged from the fiber as the distance from the lamp increases.

Charge erase device for copying or reproduction machines and printers

In touchdown-type development systems used in xerographic apparatus, an arrangement produces ambipolar development of the latent image. The arrangement utilizes only changes in electric potential in various portions of the development process to effect a polarity change from positive-to-positive (direct) development to reversal development and vice versa.

Growing community of inventors

Ontario, NY, United States of America

Lawrence M Hart