Patents by Inventor Stefan M. Wolfrum

Stefan M. Wolfrum 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).

  • Method of applying a thermally black layer to a heating member for an indirectly heated cathode
    Patent number: 4983420
    Abstract: A filament for an indirectly heated cathode is coated with a tungsten-aluminium oxide suspension, the tungsten particles being stabilized by a chemisorbed monomolecular layer of an aliphatic monocarboxylic acid such as stearic acid.
    Type: Grant
    Filed: September 20, 1989
    Date of Patent: January 8, 1991
    Assignee: U.S. Philips Corporation
    Inventors: Stefan M. Wolfrum, Johannes J. Ponjee, Angela C. L. Van de Poel