Patents by Inventor Adrianus C. H. J. Liefkens

Adrianus C. H. J. Liefkens 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: 4419415
    Abstract: A magnetic recording head may be assembled from laminar plates of ferromagnetic material which are welded together by spot welds to form a core stack. The core stack is welded by spot welds (E, F, G) to a base plate (16). The ferromagnetic material is typically an alloy of Si, Al and Fe and tends to produce stress cracks around the areas of the welds. In order to overcome this problem, the edges of the plates, at least around the areas of the welds, and provided with a layer of ductile metal such as Ni, Fe or Mo. The layer is between 5 and 500 .mu.m thick. The depth of the welds is arranged to lie substantially within the ductile metal layer.
    Type: Grant
    Filed: January 18, 1982
    Date of Patent: December 6, 1983
    Assignee: U.S. Philips Corporation
    Inventors: Adrianus C. H. J. Liefkens, Gerardus J. A. M. Notenboom
  • Patent number: 4392169
    Abstract: A magnetic tape cassette comprising a housing having an apertured wall to admit a magnetic head, tape guiding means, tape pressure means provided opposite to the aperture and a leaf spring adapted to press the tape pressure means against the tape when a magnetic tape is present in the cassette. The leaf spring consisting of one strip of a soft-magnetic metal alloy having an amorphous structure also serves as a magnetic shielding.
    Type: Grant
    Filed: May 21, 1981
    Date of Patent: July 5, 1983
    Assignee: U.S. Philips Corporation
    Inventors: Carolus J. Boullart, Adrianus C. H. J. Liefkens