Patents by Inventor Motoharu Shimizu

Motoharu Shimizu 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: 4600555
    Abstract: A method of producing a cylindrical permanent magnet having a multipole surface anisotropy. The method comprises the steps of: preparing a metal mold cooperating with a lower punch in defining therein a cylindrical compacting cavity, the metal mold being provided in the inner peripheral surface thereof with field coils corresponding in number to the number of the magnetic poles of the magnet to be produced; charging the compacting cavity with a ferromagnetic powder having a magnetic anisotropy; energizing the field coils to impart a magnetic anisotropy to the ferromagnetic powder while compacting the powder between an upper punch and the lower punch to form a compact; demagnetizing the formed compact followed by a firing; and magnetizing the fired compact in the same direction as the anisotropy. The method is characterized in that the field coils produce pulse magnetic field the intensity of which is not smaller than 3.5.times.10.sup.
    Type: Grant
    Filed: May 15, 1984
    Date of Patent: July 15, 1986
    Assignee: Hitachi Metals, Ltd.
    Inventor: Motoharu Shimizu
  • Patent number: 4547758
    Abstract: A cylindrical permanent magnet suitable for use as the rotor magnet of a stepping motor. The magnet is a sintered cylindrical permanent magnet having a composition expressed by MO.nFe.sub.2 O.sub.3, where M represents Ba, Sr, Pb or mixture thereof, while n represents a value of 5 to 6. The sintered cylindrical permanent magnet is provided on its surface with multipolar anisotropy of more than 8 (eight) magnetic poles. Disclosed also is a method of producing the cylindrical permanent magnet.
    Type: Grant
    Filed: December 2, 1982
    Date of Patent: October 15, 1985
    Assignee: Hitachi Metals, Ltd.
    Inventors: Motoharu Shimizu, Noriyuki Noda, Yoshihiro Noguchi
  • Patent number: 4412104
    Abstract: A magnetic circuit for a loudspeaker characterized in a substantially rectangular parellelepiped yoke provided with a hollow penetrating two opposed lateral faces thereof has a substantially rectangular parallelepiped sintered magnet mounted therein of a specified size and composition and having a recoil permeance coefficient from 1.0 to 1.2, a polepiece connected to the top surface of said parallelepiped sintered magnet forms a magnetic air gap with the end of a through hole formed in the top face of said rectangular yoke for a movable coil.
    Type: Grant
    Filed: November 21, 1979
    Date of Patent: October 25, 1983
    Assignee: Hitachi Metals, Ltd.
    Inventors: Osamu Fujita, Noriaki Goshi, Shinya Okayasu, Motoharu Shimizu, Nobuo Kakinuma