Patents by Inventor Donald E. Wiedrich

Donald E. Wiedrich has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6469728
    Abstract: A printbar assembly comprised of an array of light emitters, and array of gradient index lenses, and a light control film. The light control film, which is comprised of a plurality of microlouvers, is disposed such that it limits the angle at which light from the light emitters can enter the gradient index lenses. The light control film increases the depth of focus of the gradient index lens array without significantly reducing the effective radiometric efficiency.
    Type: Grant
    Filed: December 18, 1995
    Date of Patent: October 22, 2002
    Assignee: Xerox Corporation
    Inventors: George A. Charnitski, Thomas J. Hammond, Donald E. Wiedrich
  • Patent number: 5300985
    Abstract: A multi-function, multi-segment ac plasma erase lamp is provided to selectively erase previously charged areas of a photoconductive member. The lamp performs the conventional erase function of fixed edge erase, edge shift and patch generation, while adding the functions of variable edge erase along an edge to accommodate reduction images and changes in page size. Another feature of this erase lamp is a "dark" segment which is energized but is not light emitting. Its function is to enhance the turn on time for the light emitting segments. A still further improvement is the application of a voltage to a photoresist coating applied the the lamp surface to create a field which will repel toner and dust particles from that surface of the lamp.
    Type: Grant
    Filed: May 29, 1992
    Date of Patent: April 5, 1994
    Assignee: Xerox Corporation
    Inventors: John C. Demott, Charles J. Urso, Jr., Mary A. Straube, Donald E. Wiedrich, Robert W. Corbin
  • Patent number: 5008707
    Abstract: Apparatus and method for forming an electrostatic latent image on an imaging member having a photoconductive insulating layer has a voltage sensitive corona charging device with a corona generating electrode and a control electrode positioned in charging relationship to the photoconductive insulating layer, means to energize the charging device to charge the photoconductive insulating layer to a first level comprising means to apply a corona generating voltage to the corona generating electrode and to apply a control voltage of a first magnitude to the control electrode, and means to expose the photoconductive insulating layer to an image pattern simultaneously while the charging device is energized.
    Type: Grant
    Filed: September 5, 1989
    Date of Patent: April 16, 1991
    Assignee: Xerox Corporation
    Inventors: Joan R. Ewing, Donald E. Wiedrich