Patents by Inventor Franciscus M. Dreesen

Franciscus M. Dreesen 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).

  • X-ray image intensifier tube comprising a selective filter
    Patent number: 5008591
    Abstract: The entrance screen in an X-ray image intensifier includes an intermediate layer of a material which selectively absorbs photon energy. As a result, the speed of the photo-electrons is substantially reduced, thus improving the imaging. By introducing a radial variation of the absorption in the intermediate layer, vignetting-compensation can also be realized without substantial loss of sensitivity and resolution for the central portion of the tube. The resolution at the periphery of the tube can thus be substantially improved.
    Type: Grant
    Filed: January 8, 1990
    Date of Patent: April 16, 1991
    Assignee: U.S. Philips Corp.
    Inventors: Johnny van der Velden, Theodorus F. van Bergen, August L. H. Simons, Johannes K. E. Colditz, Martinus A. C. Ligtenberg, Franciscus M. Dreesen