Patents by Inventor Gerardus H. M. Siebers

Gerardus H. M. Siebers 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).

  • Low-pressure mercury vapour discharge lamp
    Patent number: 4727283
    Abstract: A low-pressure mercury vapor discharge lamp with a luminescent layer whose emission mainly lies in three spectral ranges and whose loading amounts to at least 500 W per m.sup.2 surface area of the luminescent layer, is characterized by having an absorption layer of a luminescent aluminate activated by trivalent cerium and having a garnet crystal structure. The absorption layer permits the obtaining of low color temperatures (down to 2000 K.).
    Type: Grant
    Filed: July 8, 1986
    Date of Patent: February 23, 1988
    Assignee: U.S. Philips Corporation
    Inventors: Johannes T. C. van Kemenade, Gerardus H. M. Siebers, Jean J. Heuvelmans, Johannes T. W. deHair, Johannes W. ter Vrugt
  • Gas-tight sintered translucent aluminum oxide and method
    Patent number: 4699774
    Abstract: The invention relates to gas-tight sintered translucent aluminum oxide having a density of at least 99.5%, which contains at most 1000 ppm by weight of MgO. According to the invention, the aluminum oxide also has a content of Er.sub.2 O.sub.3 lying between 20 ppm by weight and 200 ppm by weight. The material thus obtained has a great mechanical strength, a high resistance to attack by sodium and a satisfactory translucence. Thus, the material is very suitable for use as wall material for the discharge vessels of high-pressure discharge lamps.
    Type: Grant
    Filed: September 4, 1986
    Date of Patent: October 13, 1987
    Assignee: U.S. Philips Corporation
    Inventors: Peter R. Prud'Homme Van Reine, Gerardus H. M. Siebers