Patents by Inventor Doeko Stoppels

Doeko Stoppels 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).

  • Magnetic head having a core of Mn-Zn-Co ferrous ferrite
    Patent number: 4719148
    Abstract: A magnetic head for a magnetic recording and playback device. The head comprises a Mn-Zn-ferrous ferrite core having a very high saturation magnetization and magnetic permeability. The Mn-Zn-ferrous-ferrite has a composition according to the formulaMn.sub.a Zn.sub.b Fe.sub.c.sup.II Co.sbsb.xFe.sub.2.sup.III O.sbsb.4with0<a.ltoreq.0.550.06.ltoreq.b.ltoreq.0.40.34.ltoreq.c.ltoreq.0.90.0006.ltoreq.x.ltoreq.0.006.
    Type: Grant
    Filed: February 28, 1983
    Date of Patent: January 12, 1988
    Assignee: U.S. Philips Corporation
    Inventors: Doeko Stoppels, Leonardus A. H. Van Hoof
  • Magnetic head having cobalt-containing zinc-ferrous ferrite core
    Patent number: 4594628
    Abstract: A magnetic head for a magnetic recording and playback device includes a core having two core parts which are spaced from each other and between which a transducing gap is formed. The core consists of a (preferably monocrystalline) zinc-ferrous ferrite. A preferred range of compositions is defined by the formulaZn.sub.a Fe.sub.1-a.sup.II Fe.sub.2.sup.III O.sub.4, wherein 0.1.ltoreq.a.ltoreq.0.4.The Zn-ferrous ferrite may further comprise additions of Co.sup.II.
    Type: Grant
    Filed: January 14, 1983
    Date of Patent: June 10, 1986
    Assignee: U.S. Philips Corporation
    Inventors: Doeko Stoppels, Peter G. T. Boonen, Ulrich E. Enz, Leonardus A. H. van Hoof
  • Magnetic head
    Patent number: 4568993
    Abstract: Magnetic head for a magnetic recording and playback apparatus includes a core of a Mn--Zn-ferrous ferrite having a very high saturation magnetization. The Mn--Zn-ferrous ferrite has a composition (not counting optional substitutions) according to the formulaMn.sub.a Zn.sub.b Fe.sub.c.sup.II Fe.sub.e.sup.III O.sub.4with0<a.ltoreq.0.550.06.ltoreq.b.ltoreq.0.40.25.ltoreq.c.ltoreq.0.9(a+b+c=1).The result is that the magnetic head may be used in combination with magnetic tapes having a very high coercive force (up to 104 kA/m (1300 Oersted) and may be used for transducing signals having a frequency of a few MHz.
    Type: Grant
    Filed: January 24, 1983
    Date of Patent: February 4, 1986
    Assignee: U.S. Philips Corporation
    Inventors: Doeko Stoppels, Piet F. Bongers, Johannes P. M. Damen, Eelco G. Visser