Patents by Inventor Tomohito Mizuno

Tomohito Mizuno 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: 20160080914
    Abstract: A positional information sharing system, a positional information sharing method, and a positional information sharing program that is capable of sharing further accurate positions of respective users between each other.
    Type: Application
    Filed: March 20, 2014
    Publication date: March 17, 2016
    Applicant: AISIN AW CO., LTD.
    Inventors: Koji YAMASHITA, Shingo AOYAMA, Yuichi TANAKA, Tomohito MIZUNO
  • Patent number: 8773958
    Abstract: An estimation method includes a heating step in which a recording bit, on which a reference signal is recorded, is heated under each of heating conditions having different heating temperatures, the recording bit being at least one recording bit in the magnetic recording medium, and a measurement step in which a signal intensity with respect to the reference signal recorded in the recording bit after heating is measured under each of the heating conditions of the heating step. Based on the signal intensities with respect to the reference signal respectively measured in the measurement step, the distribution width of the Curie temperatures of the plurality of magnetic grains that form the magnetic recording layer is estimated.
    Type: Grant
    Filed: August 7, 2012
    Date of Patent: July 8, 2014
    Assignee: TDK Corporation
    Inventors: Satoshi Tomikawa, Tomohito Mizuno
  • Patent number: 8666692
    Abstract: In exemplary embodiments, first and second parameters are obtained for each of different temperatures of the magnetic recording layer. The absolute value of the first parameter for each magnetic grain has a minimum value when the temperature of each magnetic grain reaches a predetermined temperature that increases as the Curie temperature increases, and decreases as the Curie temperature decreases. The second parameter is related to the standard deviation of the coercivity distribution of the magnetic grains divided by the coercivity of the magnetic recording layer. The method calculates a value where the absolute measurement value of the first parameter has a minimum value and the temperature of the magnetic recording layer at which the standard deviation of the coercivity distribution of the magnetic grains divided by the coercivity of the magnetic recording layer has a maximum value.
    Type: Grant
    Filed: March 10, 2011
    Date of Patent: March 4, 2014
    Assignee: TDK Corporation
    Inventors: Tomohito Mizuno, Koji Shimazawa, Hiroshi Kiyono
  • Publication number: 20140043707
    Abstract: An estimation method includes a heating step in which a recording bit, on which a reference signal is recorded, is heated under each of heating conditions having different heating temperatures, the recording bit being at least one recording bit in the magnetic recording medium, and a measurement step in which a signal intensity with respect to the reference signal recorded in the recording bit after heating is measured under each of the heating conditions of the heating step. Based on the signal intensities with respect to the reference signal respectively measured in the measurement step, the distribution width of the Curie temperatures of the plurality of magnetic grains that form the magnetic recording layer is estimated.
    Type: Application
    Filed: August 7, 2012
    Publication date: February 13, 2014
    Applicant: TDK CORPORATION
    Inventors: Satoshi TOMIKAWA, Tomohito MIZUNO
  • Patent number: 8619510
    Abstract: A measurement method of a magnetic field gradient of a recording magnetic field generated by a magnetic head in a recording medium includes a step of locally heating the recording medium in a nonmagnetic field state where a magnetic field is not applied to the recording medium at all and measuring a temperature gradient of the recording medium in the nonmagnetic field state, a step of locally heating the recording medium in a recording magnetic field application state where the recording magnetic field is applied to the recording medium and measuring a temperature gradient of the recording medium in the recording magnetic field application state, and a step of calculating a magnetic field gradient of the recording magnetic field based on the temperature gradient of the recording medium in the nonmagnetic field state and the temperature gradient of the recording medium in the recording magnetic field application state.
    Type: Grant
    Filed: August 31, 2012
    Date of Patent: December 31, 2013
    Assignee: TDK Corporation
    Inventors: Ken-ichi Takano, Satoshi Tomikawa, Tomohito Mizuno, Hiroshi Kiyono
  • Patent number: 8614934
    Abstract: Using a thermally-assisted magnetic recording device, a reference signal is recorded to a magnetic recording medium. After heating each of first and second heating points, where the first and second heating point being positioned respectively at inner and outer sides along a track width direction with respect to a track width center point of a recording bit where the reference signal is recorded, the reproducing signal intensity of the reference signal is measured. Then, obtaining a maximum distance between the first heating point and the second heating point when a reproducing signal intensity measurement value of the reference signal after the magnetic recording medium is heated is approximately zero. Based on the maximum distance, a characterization of the thermally-assisted magnetic recording device is evaluated.
    Type: Grant
    Filed: August 10, 2012
    Date of Patent: December 24, 2013
    Assignee: TDK Corporation
    Inventors: Satoshi Tomikawa, Tomohito Mizuno, Kenichi Takano, Makoto Moriya
  • Patent number: 8599652
    Abstract: A thermally-assisted magnetic recording (TAMR) medium of the present invention includes: a magnetization direction arrangement layer on a substrate; and a magnetic recording layer on the magnetization direction arrangement layer, wherein the magnetization direction arrangement layer is made of at least one selected from a group consisting of Co, Zr, CoZr, CoTaZr, CoFeTaZrCr, CoNbZr, CoNiZr, FeCoZrBCu, NiFe, FeCo, FeAlN, (FeCo)N, FeAlSi, and FeTaC so that a spreading of the heating spot applied from the magnetic head for thermally-assisted recording to the film surface of the magnetic recording medium is suppressed, and that an SN is improved by arranging the magnetization direction of the perpendicularly written recording magnetization to become identical to a perpendicular direction, and realizing the higher recording density.
    Type: Grant
    Filed: July 14, 2011
    Date of Patent: December 3, 2013
    Assignee: TDK Corporation
    Inventors: Satoshi Tomikawa, Tomohito Mizuno
  • Patent number: 8493818
    Abstract: A thermally-assisted magnetic recording head, includes: a pole that generates a writing magnetic field from an end surface that forms a portion of an air bearing surface opposing a magnetic recording medium; a waveguide through which light for exciting a surface plasmon propagates; a plasmon generator that couples to the light in a surface plasmon mode and generates near-field light from a near-field light generating portion on a near-field light generating end surface that forms the portion of the air bearing surface; and magnetic field focusing parts that are able to focus the writing magnetic field generated from the pole and that are disposed on both sides of the pole in a track width direction from a perspective of the air bearing surface side.
    Type: Grant
    Filed: July 14, 2011
    Date of Patent: July 23, 2013
    Assignee: TDK Corporation
    Inventors: Satoshi Tomikawa, Tomohito Mizuno, Katsuki Kurihara
  • Patent number: 8472149
    Abstract: The invention provides a giant magneto-resistive effect device of the CPP (current perpendicular to plane) structure (CPP-GMR device) comprising a spacer layer, and a first ferromagnetic layer and a second ferromagnetic layer stacked together with said spacer layer sandwiched between them, with a sense current passed in the stacking direction, wherein the first ferromagnetic layer and the second ferromagnetic layer function such that the angle made between the directions of magnetizations of both layers change relatively depending on an external magnetic field, said spacer layer contains a semiconductor oxide layer, and a nitrogen element-interface protective layer is provided at a position where the semiconductor oxide layer forming the whole or a part of said spacer layer contacts an insulating layer.
    Type: Grant
    Filed: October 1, 2007
    Date of Patent: June 25, 2013
    Assignee: TDK Corporation
    Inventors: Shinji Hara, Daisuke Miyauchi, Koji Shimazawa, Yoshihiro Tsuchiya, Tomohito Mizuno, Takahiko Machita
  • Patent number: 8472150
    Abstract: A giant magneto-resistive effect device (CPP-GMR device) having the CPP (current perpendicular to plane) structure comprising a spacer layer, and a first ferromagnetic layer and a second ferromagnetic layer stacked one upon another with the spacer layer interposed between them, with a sense current applied in a stacking direction, wherein the spacer layer comprises a first nonmagnetic metal layer and a second nonmagnetic metal layer, each made of a nonmagnetic metal material, and a semiconductor oxide layer interposed between the first nonmagnetic metal layer and the second nonmagnetic metal layer, the semiconductor oxide layer that forms a part of the spacer layer contains zinc oxide as its main component wherein the main component zinc oxide contains an additive metal, and the additive metal is less likely to be oxidized than zinc.
    Type: Grant
    Filed: January 3, 2008
    Date of Patent: June 25, 2013
    Assignee: TDK Corporation
    Inventors: Yoshihiro Tsuchiya, Tomohito Mizuno, Kei Hirata, Koji Shimazawa, Shinji Hara
  • Patent number: 8374060
    Abstract: A thermally-assisted magnetic recording method includes first and second steps. The first step applies heat to part of a hard disk medium and forms a moving high-temperature region in a magnetic recording layer of the hard disk medium. The high-temperature region is higher in temperature than a region therearound and has a temperature equal to or higher than the maximum coercivity vanishing temperature of a plurality of magnetic grains contained in the magnetic recording layer. At least one magnetic grain that is adjacent to the rear end of the high-temperature region in the direction of movement of the high-temperature region has a coercivity of a value other than 0. The second step applies a write magnetic field to the hard disk medium such that the write magnetic field applied to the at least one magnetic grain adjacent to the rear end of the high-temperature region is 3 kOe or smaller in magnitude.
    Type: Grant
    Filed: March 11, 2011
    Date of Patent: February 12, 2013
    Assignee: TDK Corporation
    Inventors: Koji Shimazawa, Tomohito Mizuno, Hiroshi Kiyono
  • Publication number: 20130016591
    Abstract: A thermally-assisted magnetic recording (TAMR) medium of the present invention includes: a magnetization direction arrangement layer on a substrate; and a magnetic recording layer on the magnetization direction arrangement layer, wherein the magnetization direction arrangement layer is made of at least one selected from a group consisting of Co, Zr, CoZr, CoTaZr, CoFeTaZrCr, CoNbZr, CoNiZr, FeCoZrBCu, NiFe, FeCo, FeAlN, (FeCo)N, FeAlSi, and FeTaC so that a spreading of the heating spot applied from the magnetic head for thermally-assisted recording to the film surface of the magnetic recording medium is suppressed, and that an SN is improved by arranging the magnetization direction of the perpendicularly written recording magnetization to become identical to a perpendicular direction, and realizing the higher recording density.
    Type: Application
    Filed: July 14, 2011
    Publication date: January 17, 2013
    Applicant: TDK CORPORATION
    Inventors: Satoshi TOMIKAWA, Tomohito MIZUNO
  • Publication number: 20130016592
    Abstract: A thermally-assisted magnetic recording head, includes: a pole that generates a writing magnetic field from an end surface that forms a portion of an air bearing surface opposing a magnetic recording medium; a waveguide through which light for exciting a surface plasmon propagates; a plasmon generator that couples to the light in a surface plasmon mode and generates near-field light from a near-field light generating portion on a near-field light generating end surface that forms the portion of the air bearing surface; and magnetic field focusing parts that are able to focus the writing magnetic field generated from the pole and that are disposed on both sides of the pole in a track width direction from a perspective of the air bearing surface side.
    Type: Application
    Filed: July 14, 2011
    Publication date: January 17, 2013
    Applicant: TDK CORPORATION
    Inventors: Satoshi TOMIKAWA, Tomohito Mizuno, Katsuki Kurihara
  • Patent number: 8310791
    Abstract: A magnetoresistive effect element is structured in the manner that the antiferromagnetic layer interposed between the upper and lower shields is eliminated and the antiferromagnetic layer is positioned in a so-called shield layer. Therefore, it is realized to solve a pin reversal problem and to allow narrower tracks and narrower read gaps.
    Type: Grant
    Filed: March 13, 2009
    Date of Patent: November 13, 2012
    Assignee: TDK Corporation
    Inventors: Takahiko Machita, Tomohito Mizuno, Koji Shimazawa, Tsutomu Chou, Daisuke Miyauchi, Yoshihiro Tsuchiya, Shinji Hara, Toshiyuki Ayukawa
  • Publication number: 20120230169
    Abstract: A thermally-assisted magnetic recording method includes first and second steps. The first step applies heat to part of a hard disk medium and forms a moving high-temperature region in a magnetic recording layer of the hard disk medium. The high-temperature region is higher in temperature than a region therearound and has a temperature equal to or higher than the maximum coercivity vanishing temperature of a plurality of magnetic grains contained in the magnetic recording layer. At least one magnetic grain that is adjacent to the rear end of the high-temperature region in the direction of movement of the high-temperature region has a coercivity of a value other than 0. The second step applies a write magnetic field to the hard disk medium such that the write magnetic field applied to the at least one magnetic grain adjacent to the rear end of the high-temperature region is 3 kOe or smaller in magnitude.
    Type: Application
    Filed: March 11, 2011
    Publication date: September 13, 2012
    Applicant: TDK CORPORATION
    Inventors: Koji SHIMAZAWA, Tomohito MIZUNO, Hiroshi KIYONO
  • Publication number: 20120232831
    Abstract: In a method of estimating the Curie temperature distribution of a plurality of magnetic grains contained in a magnetic recording layer, measurement values of first and second parameters are obtained for each of different temperatures of the magnetic recording layer which is used as the measurement subject. The first parameter has such a property that the absolute value of the first parameter for each magnetic grain takes on the minimum value when the temperature of each magnetic grain reaches a predetermined temperature, wherein the predetermined temperature varies according to the Curie temperature of each magnetic grain in such a manner as to increase as the Curie temperature increases, and to decrease as the Curie temperature decreases. The second parameter is related to the standard deviation of the coervicity distribution of the magnetic grains divided by the coervicity of the magnetic recording layer.
    Type: Application
    Filed: March 10, 2011
    Publication date: September 13, 2012
    Applicant: TDK CORPORATION
    Inventors: Tomohito MIZUNO, Koji SHIMAZAWA, Hiroshi KIYONO
  • Patent number: 8203808
    Abstract: In an MR element constituted in such a manner that a pinned layer whose magnetization direction is fixed, a nonmagnetic spacer layer, and a free layer whose magnetization direction is changed according to an external magnetic field, are laminated in this order; the free layer has a multilayer constitution including a magnetic body mixed with an element having 4f electrons at a certain ratio. Specifically, the first layer in contact with the spacer layer, the third layer, the fifth layer, and the seventh layer of the free layer are formed by mixing Nd, Sm, Gd, or Tb into CoFe. The second layer and the sixth layer of the free layer are formed by mixing Nd, Sm, Gd, or Tb into NiFe. The third layer of the free layer is Cu. A damping constant of the free layer is greater than 0.018.
    Type: Grant
    Filed: October 29, 2007
    Date of Patent: June 19, 2012
    Assignee: TDK Corporation
    Inventors: Tomohito Mizuno, Yoshihiro Tsuchiya
  • Patent number: 8169731
    Abstract: Provided is a near-field light transducer with a propagation edge in which the generation of defects is suppressed. The transducer is formed of a Ag alloy and comprises an edge, the edge comprising a portion to be coupled with a light in a surface plasmon mode, the edge extending from the portion to a near-field light generating end surface, and the edge being configured to propagate surface plasmon excited by the light. Further, a curvature radius of the rounded edge is set in the range from 6.25 nm to 20 nm. In the edge and its vicinity, the generation of defects such as cracking and chipping is suppressed. Thereby improved are a propagation efficiency of surface plasmon and a light use efficiency of the transducer. The Ag alloy preferably contains at least one element selected from a group of Pd, Au, Cu, Ru, Rh and Ir.
    Type: Grant
    Filed: August 13, 2009
    Date of Patent: May 1, 2012
    Assignee: TDK Corporation
    Inventors: Tomohito Mizuno, Yoshihiro Tsuchiya, Koji Shimazawa, Tsutomu Chou
  • Patent number: 8149547
    Abstract: An MR element includes a pinned layer, a free layer and a nonmagnetic space layer or a tunnel barrier layer sandwiched between the pinned layer and the free layer. A magnetization direction of the free layer is substantially perpendicular to a film surface thereof, and a magnetization direction of the pinned layer is substantially parallel to a film surface thereof.
    Type: Grant
    Filed: March 13, 2008
    Date of Patent: April 3, 2012
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Satoshi Miura, Tomohito Mizuno
  • Patent number: 8111591
    Abstract: A heat-assisted magnetic recording head includes a slider, and an edge-emitting laser diode fixed to the slider. The slider includes: a substrate; and an MR element, two reproduction wiring layers, a coil, two recording wiring layers, a magnetic pole, a near-field light generating element, and a waveguide that are stacked above the top surface of the substrate. The two reproduction wiring layers supply a sense current to the MR element. The two recording wiring layers supply a coil current to the coil, The laser diode has an emitting end face including an emission part for emitting laser light, and a bottom surface, The laser diode is arranged so that the bottom surface faces the top surface of the slider. As viewed from above, the laser diode does not overlap the two reproduction wiring layers but overlaps at least one of the two recording wiring layers.
    Type: Grant
    Filed: July 28, 2009
    Date of Patent: February 7, 2012
    Assignee: TDK Corporation
    Inventors: Koji Shimazawa, Tomohito Mizuno, Eiji Komura