Patents by Inventor Hans J. Hirsch

Hans J. Hirsch 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).

  • Electrophotographic method of generating electrostatic images on two sides of an insulating foil
    Patent number: 4345012
    Abstract: Electrostatic charge images of identical shape but opposite sign are generated on both sides of a transparent, highly insulating foil. Subsequently, pigment is deposited on both sides of the foil by means of oppositely charged developers. The optical density of an electrophotographic image on a transparent insulating foil is increased, as compared to densities achieved in the past, for a given surface charge density by establishing a charge exchange between one side of the foil and an electrode. On the other side of the foil a charge image is generated and the foil. The electrode are separated from each other prior to development.
    Type: Grant
    Filed: February 25, 1980
    Date of Patent: August 17, 1982
    Assignee: U.S. Philips Corporation
    Inventors: Hans J. Hirsch, Horst Dannert