Patents by Inventor Sadao Sekizawa

Sadao Sekizawa 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: 4853632
    Abstract: An apparatus for magnetically detecting a position of a movable magnetic body includes a three-terminal magnetic field-intensity sensing structure formed by a pair of magneto-resistors. The magnetic field-intensity sensing structure is disposed opposite to a magnetic body arranged for movement relative thereto in a magnetic field and generates a first electrical signal of sinusoidal waveform in response to a change in the intensity of the magnetic field due to the relative movement of the magnetic body. This first electrical signal appears from the apparatus as a second electrical signal of rectangular waveform or of sinusoidal waveform having an amplified amplitude. Components of the circuit for shaping the waveform of or amplifying the amplitude of the first electrical signal are integrally mounted together with the magneto-resistors on a substrate. Preferably, the shaping or amplifying circuit is in the form of a hybrid integrated circuit formed on the substrate.
    Type: Grant
    Filed: November 24, 1981
    Date of Patent: August 1, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Yoosuke Nagano, Sadao Sekizawa, Toshio Seki
  • Patent number: 4639807
    Abstract: A magnetic detector for detecting the angle, position speed of rotation of a rotating body or the rectinear position, distance or speed of a rectinearly moving body is used opposite to a magnetic recording medium. The magnetic detector includes a plurality of elongated stripe-shaped magnetoresistive elements juxtaposed on a non-magnetic substrate. Bridge output terminals are provided adjoining to first identical ends of the respective magnetoresistive elements in the longitudinal directions thereof while common terminals are disposed adjoining to second ends of the magnetoresistive elements. Either bridge output or common terminals extend round the outside of the magnetoresistive elements to positions adjacent to the common or bridge output terminals.
    Type: Grant
    Filed: March 15, 1983
    Date of Patent: January 27, 1987
    Assignee: Hitachi, Ltd.
    Inventors: Sadao Sekizawa, Toshio Seki, Tadashi Takahashi
  • Patent number: 4628259
    Abstract: The invention discloses a movement detecting device for detecting the movement state of a moving body such as a rotating body, in which a magnetic recording medium on which N and S magnetic poles are alternately recorded at a constant interval is fixed symmetrically with respect to a rotary shaft of a rotating body whose rotation state is to be detected, and an MR element comprising magnet-resistive elements is mounted at a fixed position relative to the magnetic recording medium so that the rotation state of the rotating body can be detected from variation of the values of resistance of the magnet-resistive elements caused by the rotation of the body. N and S poles are recorded on the magnetic recording medium with a small pole pitch P. The magnet-resistive elements are formed to have a width sufficiently smaller than the pole pitch.
    Type: Grant
    Filed: September 28, 1981
    Date of Patent: December 9, 1986
    Assignee: Hitachi, Ltd.
    Inventors: Tadashi Takahashi, Hiroshi Hayashida, Kunio Miyashita, Sadao Sekizawa
  • Patent number: RE34355
    Abstract: The invention discloses a movement detecting device for detecting the movement state of a moving body such as a rotating body, in which a magnetic recording medium on which N and S magnetic poles are alternately recorded at a constant interval is fixed symmetrically with respect to a rotary shaft of a rotating body whose rotation state is to be detected, and an MR element comprising magnet-resistive elements is mounted at a fixed position relative to the magnetic recording medium so that the rotation state of the rotating body can be detected from variation of the values of resistance of the magnet-resistive elements caused by the rotation of the body. N and S poles are recorded on the magnetic recording medium with a small pole pitch P. The magnet-resistive elements are formed to have a width sufficiently smaller than the pole pitch.
    Type: Grant
    Filed: April 18, 1991
    Date of Patent: August 24, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Tadashi Takahashi, Hiroshi Nishida, Kunio Miyashita, Sadao Sekizawa