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).
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Patent number: 6731478Abstract: 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: GrantFiled: March 28, 2003Date of Patent: May 4, 2004Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Publication number: 20040037002Abstract: Disclosed herein is a magnetic head for perpendicular recording in which the main magnetic pole has reduced remanent magnetization and is less liable to cause erasure after recording. These characteristic properties were realized by constructing the magnetic head such that the recording magnetic pole and the yoke are separate from each other and the main magnetic pole is formed from a material with a high saturation magnetic flux density and the yoke is formed from a material having a negative magnetostriction constant.Type: ApplicationFiled: January 31, 2003Publication date: February 26, 2004Applicant: Hitachi, Ltd.Inventors: Kazue Kudo, Yoshiaki Kawato, Kazuhiro Nakamoto, Nobuo Yoshida, Kimitoshi Etoh
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Patent number: 6693774Abstract: 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: GrantFiled: March 12, 2001Date of Patent: February 17, 2004Assignee: Hitachi, Ltd.Inventors: Katsuro Watanabe, Hiromasa Takahashi, Nobuo Yoshida, Takashi Kawabe, Kazuhiro Nakamoto
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Publication number: 20030223149Abstract: 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: ApplicationFiled: January 3, 2003Publication date: December 4, 2003Applicant: Hitachi, Ltd.Inventors: Hisashi Kimura, Kazuhiro Nakamoto, Yoshiaki Kawato, Nobuo Yoshida
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Patent number: 6643105Abstract: 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: GrantFiled: August 8, 2002Date of Patent: November 4, 2003Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Hiroyuki Hoshiya, Takashi Kawabe, Hiromasa Takahashi, Hisashi Kimura, Katsuro Watanabe, Chiaki Ishikawa, Kaori Totsuka
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Publication number: 20030184923Abstract: 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: ApplicationFiled: March 28, 2003Publication date: October 2, 2003Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Patent number: 6545847Abstract: 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: GrantFiled: December 19, 2001Date of Patent: April 8, 2003Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Patent number: 6507465Abstract: 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: GrantFiled: October 4, 2000Date of Patent: January 14, 2003Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Publication number: 20020191352Abstract: 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: ApplicationFiled: August 8, 2002Publication date: December 19, 2002Inventors: Kazuhiro Nakamoto, Hiroyuki Hoshiya, Takashi Kawabe, Hiromasa Takahashi, Hisashi Kimura, Katsuro Watanabe, Chiaki Ishikawa, Kaori Totsuka
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Patent number: 6456466Abstract: 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: GrantFiled: March 20, 2000Date of Patent: September 24, 2002Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Hiroyuki Hoshiya, Takashi Kawabe, Hiromasa Takahashi, Hisashi Kimura, Katsuro Watanabe, Chiaki Ishikawa, Kaori Totsuka
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Publication number: 20020044395Abstract: 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: ApplicationFiled: December 19, 2001Publication date: April 18, 2002Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Publication number: 20020028356Abstract: 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: ApplicationFiled: May 22, 2001Publication date: March 7, 2002Inventors: Yoshiaki Kawato, Masaaki Futamoto, Kazuhiro Nakamoto
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Publication number: 20010028538Abstract: 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: ApplicationFiled: March 12, 2001Publication date: October 11, 2001Inventors: Katsuro Watanabe, Hiromasa Takahashi, Nobuo Yoshida, Takashi Kawabe, Kazuhiro Nakamoto
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Patent number: 6275360Abstract: 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: GrantFiled: September 24, 1998Date of Patent: August 14, 2001Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Takashi Kawabe, Tetsuo Kobayashi, Shun-ichi Marumi, Shinji Narishige, Takao Imagawa
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Patent number: 6141190Abstract: 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: GrantFiled: June 15, 1999Date of Patent: October 31, 2000Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Patent number: 5969896Abstract: 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: GrantFiled: January 6, 1997Date of Patent: October 19, 1999Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato, Hiroshi Fukui, Hiroyuki Hoshiya
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Patent number: 5936810Abstract: 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: GrantFiled: February 6, 1997Date of Patent: August 10, 1999Assignee: Hitachi, Ltd.Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
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Patent number: 5590008Abstract: 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: GrantFiled: October 17, 1994Date of Patent: December 31, 1996Assignee: Hitachi, Ltd.Inventors: Masanori Tanabe, Hiroshi Fukui, Tadayuki Iwakura, Kazuhiro Nakamoto, Moriaki Fuyama, Katsuya Mitsuoka, Masaaki Sano, Makoto Saito, Makoto Aihara, Shuji Sudo