Patents by Inventor Christiaan Hendrik Frans Velzel

Christiaan Hendrik Frans Velzel 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).

  • Apparatus for reading an optically recorded record carrier provided with periodic surface undulations and for deriving a focussing control signal from such surface undulations
    Patent number: 4038679
    Abstract: An apparatus for reading a record carrier on which information is stored in an optically readable structure of trackwise arranged areas and intermediate areas where at least one of the surfaces of the record carrier body has periodic surface undulations along the track direction. A focussing error signal is derived by reflecting a focussed light beam on the record surface and by measuring the amplitude and phase of the portion of the reflected beam that corresponds to the surface undulations.
    Type: Grant
    Filed: October 29, 1975
    Date of Patent: July 26, 1977
    Assignee: U.S. Philips Corporation
    Inventors: Gijsbertus Bouwhuis, Christiaan Hendriks Frans Velzel
  • Record carrier on which information is stored in an optically readable structure with dither focussing signals also being stored
    Patent number: 3999008
    Abstract: A record carrier is described on which information is stored in an optically readable structure of trackwise arranged areas and intermediate areas. By giving at least one of the surfaces of the record carrier body excursions which are periodically variable in the track direction, it is possible in a simple manner to obtain an indication of the focussing of the read beam on the information structure during reading of the record carrier.
    Type: Grant
    Filed: April 29, 1974
    Date of Patent: December 21, 1976
    Assignee: U.S. Philips Corporation
    Inventors: Gijsbertus Bouwhuis, Christiaan Hendrik Frans Velzel
  • Apparatus for optically reading a record carrier by means of an autofocus device
    Patent number: 3992575
    Abstract: An apparatus is described for reading a record carrier on which information is stored in an optically readable reflecting structure. By projecting two radiation spots one before and one behind the plane of the information structure, it is possible to ascertain whether a read beam is properly focussed on the information structure.
    Type: Grant
    Filed: November 26, 1974
    Date of Patent: November 16, 1976
    Assignee: U.S. Philips Corporation
    Inventors: Christiaan Hendrik Frans Velzel, Peter Ferdinand Greve