Patents by Inventor Helmut Hieber

Helmut Hieber 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).

  • Contact screen for contrast control
    Patent number: 4674838
    Abstract: A contact screen for controlling contrast in producing color reproductions by the two-sheet diffusion transfer process yields sharply defined edges and faithful color reproductions without a screen structure if every screen element has a constant measured density from edge to edge that is in the range between 0.90 and 1.40 and if the integral density of the contact screen is between 0.30 and 0.40; the covered surface area occupied by the screen elements amounts to between 40% and 50% of the total surface area of the contact screen. The contact screen can be used for both opaque originals and transparencies.
    Type: Grant
    Filed: August 20, 1985
    Date of Patent: June 23, 1987
    Assignee: Raster-Union Efha Kohinoor GmbH & Co., KG
    Inventors: Helmut Hieber, Horst Scharz
  • Half tone screen for rotary gravure printing
    Patent number: 4155766
    Abstract: The opaque elements of a half-tone screen for gravure printing using a rotary printing machine are connected with each other by fine connections extending in the direction of cylinder movement.
    Type: Grant
    Filed: December 21, 1976
    Date of Patent: May 22, 1979
    Inventors: Helmut Hieber, Horst Schwarz