Patents by Inventor Kazuhiro Nakamoto

Kazuhiro Nakamoto 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: 6693774
    Abstract: A magnetoresistive sensor which, despite a narrow reproducing shield gap, affords high resolution and high reproducing output because of its structure and is able to minimize the amount of sense current leaking into the shield layer through the gap layer. A magnetic storage apparatus suitable for high-density recording is provided with a magnetic head having said magnetoresistive sensor. The structure is characterized in that at least either of the lower shield layer or upper shield layer is partly or entirely a magnetic layer which is a composite film composed of ferromagnetic metal and oxide, and an insulation protective film is arranged between the electrode film or longitudinal bias film and the magnetic film which is a composite film composed of ferromagnetic metal and oxide.
    Type: Grant
    Filed: March 12, 2001
    Date of Patent: February 17, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Katsuro Watanabe, Hiromasa Takahashi, Nobuo Yoshida, Takashi Kawabe, Kazuhiro Nakamoto
  • Publication number: 20030223149
    Abstract: There is provided a perpendicular magnetic recording and reproducing system in which the overwrite erase ratio of a perpendicular magnetic head has been improved to prevent the deterioration of an overwrite property. In the perpendicular magnetic head, a third magnetic pole composed of a soft magnetic layer is formed on the leading side of a recording magnetic pole via a non-magnetic layer, thereby reducing magnetic interference from magnetization on a medium with the recording magnetic pole and preventing the deterioration of the overwrite property.
    Type: Application
    Filed: January 3, 2003
    Publication date: December 4, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Hisashi Kimura, Kazuhiro Nakamoto, Yoshiaki Kawato, Nobuo Yoshida
  • Patent number: 6643105
    Abstract: A magnetic head include a pair of magnetic shield layers, a pair of gap layers formed between the pair of magnetic shield layers, a magnetoresistive layer arranged between the pair of gap layers, and a pair of electrodes electrically connected to the magnetoresistive layer. At least one of the pair of magnetic shield layers is formed as a discontinuous multi-layer or as a mixed layer.
    Type: Grant
    Filed: August 8, 2002
    Date of Patent: November 4, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Hiroyuki Hoshiya, Takashi Kawabe, Hiromasa Takahashi, Hisashi Kimura, Katsuro Watanabe, Chiaki Ishikawa, Kaori Totsuka
  • Publication number: 20030184923
    Abstract: A slider includes an air-introducing plane, a groove, an air flow-out end, and a thin-film magnetic head formed on the air flow-out end. The thin-film 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 thin-film 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 directly overlapping both end domains 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: March 28, 2003
    Publication date: October 2, 2003
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
  • Patent number: 6545847
    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: Grant
    Filed: December 19, 2001
    Date of Patent: April 8, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
  • Patent number: 6507465
    Abstract: A magnetic head includes a magnetoresistive effect film and a pair of electrodes contacting the magnetoresistive effect film such that the electrodes overlap the magnetoresistive effect film. The magnetoresistive effect film 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 by the antiferromagnetic film, and a non-magnetic conductive film disposed between the first ferromagnetic film and the second ferromagnetic film.
    Type: Grant
    Filed: October 4, 2000
    Date of Patent: January 14, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
  • Publication number: 20020191352
    Abstract: A magnetic head include a pair of magnetic shield layers, a pair of gap layers formed between the pair of magnetic shield layers, a magnetoresistive layer arranged between the pair of gap layers, and a pair of electrodes electrically connected to the magnetoresistive layer. At least one of the pair of magnetic shield layers is formed as a discontinuous multi-layer or as a mixed layer.
    Type: Application
    Filed: August 8, 2002
    Publication date: December 19, 2002
    Inventors: Kazuhiro Nakamoto, Hiroyuki Hoshiya, Takashi Kawabe, Hiromasa Takahashi, Hisashi Kimura, Katsuro Watanabe, Chiaki Ishikawa, Kaori Totsuka
  • Patent number: 6456466
    Abstract: The present invention is to realize a magnetic recording and reproducing apparatus in which even if a spacing between shields of a magnetic head is narrowed, a deterioration in characteristic caused by a short-circuiting between a magnetoresistive layer and a magnetic shield layer is prevented to provide a high recording density. The present invention comprises an upper shield layer 15, a lower shield layer 13,and a magnetoresistive layer 14 arranged therebetween. Further, there is provided a constitution in which one or both shield layers has (have) a high resistance layer comprising a mixed layer of ferromagnetic metal and an insulating material, or a discontinuous multi-layer having a plurality of ferromagnetic metal layers and a plurality of insulating material layers laminated alternately, to prevent a deterioration in characteristic caused by a short-circuiting.
    Type: Grant
    Filed: March 20, 2000
    Date of Patent: September 24, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Hiroyuki Hoshiya, Takashi Kawabe, Hiromasa Takahashi, Hisashi Kimura, Katsuro Watanabe, Chiaki Ishikawa, Kaori Totsuka
  • 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: 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
  • Publication number: 20010028538
    Abstract: A magnetoresistive sensor which, despite a narrow reproducing shield gap, affords high resolution and high reproducing output because of its structure to minimize the amount of sense current leaking into the shield layer through the gap layer. A magnetic storage apparatus suitable for high-density recording which is provided with a magnetic head having said magnetoresistive sensor. The structure is characterized in that at least either of the lower shield layer or upper shield layer is partly or entirely a magnetic layer which is a composite film composed of ferromagnetic metal and oxide, and an insulation protective film is arranged between the electrode film or longitudinal bias film and the magnetic film which is a composite film composed of ferromagnetic metal and oxide.
    Type: Application
    Filed: March 12, 2001
    Publication date: October 11, 2001
    Inventors: Katsuro Watanabe, Hiromasa Takahashi, Nobuo Yoshida, Takashi Kawabe, Kazuhiro Nakamoto
  • Patent number: 6275360
    Abstract: A read-write head is capable of suppressing fluctuation on a reproduced waveform caused by repetition of a writing and reading operation, and is capable suppressing noise appearing in the reproduced waveform just after a writing operation is carried out. The read-write head has an upper magnetic core, an upper shield also serving as an lower magnetic core, a lower shield and a magnetoresistive film arranged between the upper shield and the lower shield. The upper shield has a soft magnetic film having a magnitude of anisotropy field of 5 to 30 Oe, or is a multilayer film composed of a high saturation magnetic flux density film and a negative magneto-striction film. The lower shield has a soft magnetic film having a magnitude of anisotropy field of 5 to 30 Oe.
    Type: Grant
    Filed: September 24, 1998
    Date of Patent: August 14, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Takashi Kawabe, Tetsuo Kobayashi, Shun-ichi Marumi, Shinji Narishige, Takao Imagawa
  • 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
  • Patent number: 5590008
    Abstract: A magnetic disc unit has a thin film magnetic head in which a lower magnetic core and an upper magnetic core form a magnetic circuit. The upper magnetic core is constructed by magnetic films having at least two layers. A saturation magnetic flux density of the inside magnetic film, of the magnetic films having at least two layers, facing a magnetic gap of the magnetic circuit is larger than that of the outside magnetic films of the upper magnetic core and the lower magnetic core.
    Type: Grant
    Filed: October 17, 1994
    Date of Patent: December 31, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Masanori Tanabe, Hiroshi Fukui, Tadayuki Iwakura, Kazuhiro Nakamoto, Moriaki Fuyama, Katsuya Mitsuoka, Masaaki Sano, Makoto Saito, Makoto Aihara, Shuji Sudo