Patents by Inventor Franciscus J. A. M. Greidanus

Franciscus J. A. M. Greidanus 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).

  • Patent number: 5371721
    Abstract: A method and apparatus for writing and reading information in the form of a pattern of magnetic domains in an information layer of a record carrier. An optical scanning beam is focused to a diffraction-limited radiation spot, and a magnetic field is generated by a coil supplied with an energizing current the amplitude of which is modulated by the information signal to be recorded. The magnetic field is thereby modulated, and produces magnetic domains in the information layer such that each domain has a variable number of sub-domains and consequently a variable magnetization ratio, as determined by the information signal. This permits recording at an information density exceeding that corresponding to the size of the radiation spot.
    Type: Grant
    Filed: December 28, 1992
    Date of Patent: December 6, 1994
    Assignee: U.S. Philips Corporation
    Inventors: Franciscus J. A. M. Greidanus, Johannes H. M. Spruit, Bernardus A. J. Jacobs
  • Patent number: 5109375
    Abstract: A record carrier for thermomagnetic recording of information and magneto-optical readout of the recorded information. The record carrier includes a substrate and a recording layer thereon in the form of multi-layers of magnetic and non-magnetic material, the magnetic layers predominately containing cobalt and the non-magnetic layers predominantly containing transition metal. The magnetic and non-magnetic layers alternate, and the overall thickness of the complete multi-layer recording layer is less than 75 nm. Such a recording layer achieves a significant improvement in both thermomagnetic write properties and magneto-optical read properties.
    Type: Grant
    Filed: July 24, 1989
    Date of Patent: April 28, 1992
    Assignee: U.S. Philips Corporation
    Inventors: Franciscus J. A. M. Greidanus, Peter F. Carcia, Wouter B. Zeper, Friedrich J. A. den Broeder, Willem F. Godlieb