Patents by Inventor Yoshiaki Kawato

Yoshiaki Kawato 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).

  • Publication number: 20020075608
    Abstract: An object of the present invention is to provide a differential detection read sensor for perpendicular magnetic recording using two magnetic resistance elements; and to provide a thin film head for perpendicular recording using the read sensor and a magnetic recording apparatus having high recording density equipped with the head. The object of the present invention can be achieved by a reproducing sensor comprising a pair of magnetic resistance layers; a non-magnetic conductive layer; a pair of conductive layers; and a pair of magnetic shields.
    Type: Application
    Filed: August 30, 2001
    Publication date: June 20, 2002
    Applicant: Hitachi, Ltd.
    Inventor: Yoshiaki Kawato
  • Publication number: 20020044395
    Abstract: A magnetic head includes a magnetoresistive effect type film, which includes a first ferromagnetic film having a direction of magnetization which is changeable, an antiferromagnetic film, a second ferromagnetic film having a direction of magnetization which is fixed, and a non-magnetic conductive film disposed between the first ferromagnetic film and the second ferromagnetic film. The magnetic head further includes a pair of magnetic domain control films respectively arranged at ends of the magnetoresistive effect type film, and a pair of electrodes respectively arranged at the ends of the magnetoresistive effect type film. A spacing between the electrodes is narrower than a spacing between the magnetic domain control films.
    Type: Application
    Filed: December 19, 2001
    Publication date: April 18, 2002
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
  • Publication number: 20020034043
    Abstract: A magnetic head for perpendicular recording without writing from the lateral sides of a main pole and without erasing data on adjacent tracks. A magnetic disk storage apparatus using the magnetic head. The lateral side of the main pole of a magnetic head for perpendicular recording may have an inverted tapered shape obtained by forming a groove as a track portion to an inorganic insulating layer and then forming a magnetic layer and then flattening the upper surface. A leading edge, a trailing edge, or both lateral edges of the magnetic head may be tapered. The taper may be either smooth and linear or curved in profile.
    Type: Application
    Filed: August 3, 2001
    Publication date: March 21, 2002
    Inventors: Tomohiro Okada, Yoshiaki Kawato, Yasutaka Nishida, Yasuo Wakaki, Masafumi Mochizuki, Hisashi Takano
  • Publication number: 20020028356
    Abstract: An improved perpendicular magnetic recording medium and an improved magnetic storage apparatus are provided, which are suitable for high speed and high density magnetic recording. A magnetic under layer of a two-layered perpendicular magnetic recording medium includes three layers: a ferromagnetic layer; a non-magnetic layer; and a ferromagnetic layer, wherein the ferromagnetic layers are antiferromagnetically coupled with each other, thereby preventing a magnetic flux from a magnetic wall in a magnetic under layer from entering a read back head.
    Type: Application
    Filed: May 22, 2001
    Publication date: March 7, 2002
    Inventors: Yoshiaki Kawato, Masaaki Futamoto, Kazuhiro Nakamoto
  • Patent number: 6325900
    Abstract: A magnetic sensor utilizing a spin tunnel magneto-resistance effect (TMR), comprising a tunnel insulating film, a first magnetic layer formed on one of the planes of the tunnel insulating film, a second magnetic layer formed on the other plane of the tunnel insulating film, a third magnetic layer containing an anti-ferromagnetic substance for fixing magnetization of the second magnetic layer, a second insulating film formed on at least one of the first and third magnetic layers and having an opening in a predetermined region, a first electrode electrically connected to one of the first and third magnetic layers only in the opening of the second insulating film, and a second electrode for causing a current to flow between the first electrode and itself through at least the first and second magnetic layers and the first insulating layer.
    Type: Grant
    Filed: August 30, 2000
    Date of Patent: December 4, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Matahiro Komuro, Yoshiaki Kawato
  • Patent number: 6327123
    Abstract: A magnetic head is provided with a magnetoresistive sensor scarcely susceptible to heat and provided with a fixed layer capable of creating a pinned magnetic field of a sufficient intensity. The magnetic head comprises a magnetoresistive effect film having a free layer (21), a fixed layer (105) and an intermediate layer (104), and a pair of electrodes (25a, 25b) for supplying current to the magnetoresistance effect film. The free layer (21) is formed of a ferromagnetic material and the intermediate layer (104) is formed of a nonmagnetic material. The fixed layer (105) has a first ferromagnetic film (22), a second ferromagnetic film (24) and a nonmagnetic film (23) sandwiched between the first and the second ferromagnetic films (22, 24). The second ferromagnetic film (24) farther from the free layer (21) than the first ferromagnetic layer (22) is formed of a material having the property of permanent magnets.
    Type: Grant
    Filed: August 4, 1999
    Date of Patent: December 4, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Yoshiaki Kawato, Hiroshi Fukui, Kenichi Meguro, Yoshihiro Hamakawa
  • Patent number: 6327107
    Abstract: A magnetic sensor utilizing a spin tunnel magneto-resistance effect (TMR), comprising a tunnel insulating film, a first magnetic layer formed on one of the planes of the tunnel insulating film, a second magnetic layer formed on the other plane of the tunnel insulating film, a third magnetic layer containing an anti-ferromagnetic substance for fixing magnetization of the second magnetic layer, a second insulating film formed on at least one of the first and third magnetic layers and having an opening in a predetermined region, a first electrode electrically connected to one of the first and third magnetic layers only in the opening of the second insulating film, and a second electrode for causing a current to flow between the first electrode and itself through at least the first and second magnetic layers and the first insulating layer.
    Type: Grant
    Filed: April 29, 1999
    Date of Patent: December 4, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Matahiro Komuro, Yoshiaki Kawato
  • Publication number: 20010040777
    Abstract: A magnetoresistive sensor employing a magnetoresistive sensor film of a GMR film or a TMR film and a magnetic flux guide to ensure high sensitivity and high stability.
    Type: Application
    Filed: March 20, 2001
    Publication date: November 15, 2001
    Inventors: Katsuro Watanabe, Yoshiaki Kawato, Reiko Arai
  • Publication number: 20010026423
    Abstract: The invention provides a magnetoresistive effect sensor that is a yoke type magnetoresistive effect sensor having a tunnel magnetoresistive effect film, which is operated stably with suppressed Barkhausen noise, and provides a reproducing head and a magnetic disk apparatus that use the magnetoresistive effect sensor. The magnetoresistive effect sensor is provided with a tunnel magnetoresistive effect film, a pair of electrodes for supplying a current in the film thickness direction of the magnetoresistive effect film, and a magnetic flux guide for guiding a magnetic flux from the recording medium surface to the magnetoresistive effect film, wherein the magnetic domain of a free layer of the tunnel type magnetoresistive effect film and the magnetic domain of the magnetic flux guide are both controllable together.
    Type: Application
    Filed: March 19, 2001
    Publication date: October 4, 2001
    Inventors: Reiko Arai, Yoshiaki Kawato, Katsuro Watanabe
  • Publication number: 20010005301
    Abstract: A magnetic sensor utilizing a spin tunnel magneto-resistance effect (TMR), comprising a tunnel insulating film, a first magnetic layer formed on one of the planes of the tunnel insulating film, a second magnetic layer formed on the other plane of the tunnel insulating film, a third magnetic layer containing an anti-ferromagnetic substance for fixing magnetization of the second magnetic layer, a second insulating film formed on at least one of the first and third magnetic layers and having an opening in a predetermined region, a first electrode electrically connected to one of the first and third magnetic layers only in the opening of the second insulating film, and a second electrode for causing a current to flow between the first electrode and itself through at least the first and second magnetic layers and the first insulating layer.
    Type: Application
    Filed: January 24, 2001
    Publication date: June 28, 2001
    Inventors: Matahiro Komuro, Yoshiaki Kawato
  • Patent number: 6141190
    Abstract: A magnetoresistive effect head which can produce a high reproduced output independently from a strength of a magnetic domain control layer even when an electrode spacing is small, and a magnetic recording and reproducing apparatus using the same are provided. A magnetoresistive effect film is formed by a stacked layer of a first ferromagnetic film, a non-magnetic conductive film and a second ferromagnetic film. The second ferromagnetic film is stacked on an antiferromagnetic film, and magnetic domain control layers are arranged on the widthwise opposite sides of the magnetoresistive effect film. A pair of electrodes are arranged on each magnetic domain control layers with the electrode spacing being smaller than the width of the magnetoresistive effect film so that a current flows only in a central area of the magnetoresistive effect film.
    Type: Grant
    Filed: June 15, 1999
    Date of Patent: October 31, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
  • Patent number: 5969896
    Abstract: A magnetic recording/reproducing device has an inductive write element provided with a coil and magnetic cores for recording information on a medium, a magnetoresistive read element for transducing a change in a magnetic field leaking from a medium, on which information is recorded, into an electrical signal, a detector for detecting an output signal of the read element, a bias field applying unit for applying a bias field to the read element, and a recording/reproducing operation controller for reproducing information based on an output signal from the read element and for controlling the recording current applying unit based on an inputted signal to record information. The recording/reproducing operation control unit has a stabilizing unit for controlling the bias field applying unit to make an absolute value of the bias field in a state where a magnetic field leaking from the medium is applied to the read element larger than that during a normal reproducing operation.
    Type: Grant
    Filed: January 6, 1997
    Date of Patent: October 19, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato, Hiroshi Fukui, Hiroyuki Hoshiya
  • Patent number: 5936810
    Abstract: A magnetoresistive effect head which can produce a high reproduced output independently from a strength of a magnetic domain control layer even when an electrode spacing is small, and a magnetic recording and reproducing apparatus using the same are provided. A magnetoresistive effect film is formed by a stacked layer of a first ferromagnetic film, a non-magnetic conductive film and a second ferromagnetic film. The second ferromagnetic film is stacked on an antiferromagnetic film, and magnetic domain control layers are arranged on the widthwise opposite sides of the magnetoresistive effect film. A pair of electrodes are arranged on each magnetic domain control layers with the electrode spacing being smaller than the width of the magnetoresistive effect film so that a current flows only in a central area of the magnetoresistive effect film.
    Type: Grant
    Filed: February 6, 1997
    Date of Patent: August 10, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato