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).

  • Patent number: 6731478
    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: Grant
    Filed: March 28, 2003
    Date of Patent: May 4, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Nakamoto, Yoshiaki Kawato
  • Patent number: 6728081
    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: Grant
    Filed: April 21, 2003
    Date of Patent: April 27, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Reiko Arai, Yoshiaki Kawato, Katsuro Watanabe
  • Publication number: 20040061978
    Abstract: An object of the present invention is to produce 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: October 1, 2003
    Publication date: April 1, 2004
    Applicant: Hitachi, Ltd.
    Inventor: Yoshiaki Kawato
  • Patent number: 6710973
    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: Grant
    Filed: August 3, 2001
    Date of Patent: March 23, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Tomohiro Okada, Yoshiaki Kawato, Yasutaka Nishida, Yasuo Wakaki, Masafumi Mochizuki, Hisashi Takano
  • Publication number: 20040047079
    Abstract: The invention provides a magnetic head for perpendicular recording capable of recording with high linear recording density and high track density, and a magnetic disk drive incorporating the same. In order to achieve this, one or more sides of the main pole of the magnetic head for perpendicular recording except for the trailing side are formed in a taper with an appropriate angle against the tip surface of the main pole, and the yoke whose widest principal plane is in parallel to the tip surface is provided on the bottom of the main pole.
    Type: Application
    Filed: August 27, 2003
    Publication date: March 11, 2004
    Applicant: Hitachi, Ltd.
    Inventors: Kenchi Ito, Yoshiaki Kawato, Masafumi Mochizuki
  • Publication number: 20040037002
    Abstract: 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: Application
    Filed: January 31, 2003
    Publication date: February 26, 2004
    Applicant: Hitachi, Ltd.
    Inventors: Kazue Kudo, Yoshiaki Kawato, Kazuhiro Nakamoto, Nobuo Yoshida, Kimitoshi Etoh
  • Patent number: 6671136
    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: Grant
    Filed: March 19, 2001
    Date of Patent: December 30, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Reiko Arai, Yoshiaki Kawato, Katsuro Watanabe
  • 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: 6657823
    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: Grant
    Filed: August 30, 2001
    Date of Patent: December 2, 2003
    Assignee: Hitachi, Ltd.
    Inventor: Yoshiaki Kawato
  • Patent number: 6636391
    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. Magnetization of a magnetic flux guide and a first ferromagnetic layer, which is a free layer of a GMR sensor film or a TMR sensor film, are made to antiferromagnetically couple to each other via a nonmagnetic intermediate layer 21. Since net magnetic moment has become small in the area in which the magnetoresistive sensor film is arranged, and an angle of magnetization of the ferromagnetic layer rotated by magnetic field which has been guided by the magnetic flux guide enlarges, high sensitivity can be obtained. When a longitudinal biasing layer is provide for the magnetic flux guide, longitudinal biasing magnetic field is applied to the ferromagnetic layer as well which is antiferromagnetically coupled to the magnetic flux guide, thus being able to suppress Barkhausen noise of both the magnetic flux guide and the ferromagnetic layer.
    Type: Grant
    Filed: March 20, 2001
    Date of Patent: October 21, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Katsuro Watanabe, Yoshiaki Kawato, Reiko Arai
  • Publication number: 20030189797
    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: April 21, 2003
    Publication date: October 9, 2003
    Inventors: Reiko Arai, Yoshiaki Kawato, Katsuro Watanabe
  • 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
  • Publication number: 20030151850
    Abstract: A single-pole type magnetic head for perpendicular recording which reduces the amount of side writing even in the presence of a yaw angle and prevents the effective track width from decreasing, and a magnetic recording disk apparatus using the same. A main pole is composed of at least two portions where the width of the first portion continuously increases from the upstream side to the downstream side in the medium moving direction and the width of the second portion is the same as the width of the first portion's downstream edge in the medium moving direction and is constant from the upstream side to the downstream side in the medium moving direction. This prevents the recording magnetic field strength from decreasing at the track edge and increases the effective track width while suppressing side writing, thereby realizing a magnetic recording disk apparatus with a high track density.
    Type: Application
    Filed: December 9, 2002
    Publication date: August 14, 2003
    Inventors: Atsushi Nakamura, Masafumi Mochizuki, Tomohiro Okada, Kimitoshi Etoh, Isao Nunokawa, Yoshiaki Kawato
  • Patent number: 6587318
    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: November 13, 2001
    Date of Patent: July 1, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Matahiro Komuro, 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
  • Publication number: 20030026039
    Abstract: The invention fabricates a perpendicular recording head eliminating influence of external magnetic field and provides a magnetic disk drive having high stability by using the magnetic recording head and constructs a structure in which shield against external magnetic field is formed from a main pole via a gap layer and an edge portion thereof is recessed from a surface against a medium. By providing the shield against the external magnetic field, the influence of the external magnetic field is restrained and by recessing the edge from the surface against the medium, leakage of magnetic field from the shield against the external magnetic field to the medium is prevented to thereby prevent a magnetization signal from being erased.
    Type: Application
    Filed: February 11, 2002
    Publication date: February 6, 2003
    Inventors: Tomohiro Okada, Yoshiaki Kawato, Kaori Suzuki, Hiroshi Fukui, Isao Nunokawa
  • 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
  • Patent number: 6504690
    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: January 24, 2001
    Date of Patent: January 7, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Matahiro Komuro, Yoshiaki Kawato
  • Publication number: 20030002211
    Abstract: Provided is a thin film single pole head for perpendicular magnetic recording, which has a structure offering a high formatted volume, easy servo, difficulty of influencing a recording pattern on a medium, and capability of shortening processing time. This thin film single pole head for perpendicular magnetic recording is formed on a reproducing head composed of a pair of shield layers formed on a substrate, and a reproducing element formed therebetween. A structure is provided, where an auxiliary pole is not disposed between the reproducing element of the reproducing head and the main pole of a recording head when seen from a surface facing to recording media.
    Type: Application
    Filed: February 8, 2002
    Publication date: January 2, 2003
    Inventors: Yuko Tsuchiya, Hiroyuki Hoshiya, Yoshiaki Kawato, Katsuro Watanabe, Hiroshi Ide
  • Publication number: 20020097536
    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: November 13, 2001
    Publication date: July 25, 2002
    Applicant: Hitachi, Ltd.
    Inventors: Matahiro Komuro, Yoshiaki Kawato