Patents by Inventor Koichi Terunuma

Koichi Terunuma 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: 20110068786
    Abstract: A magnetic sensor includes: a first and a second magnetoresistive elements each including: a magnetization free layer; a nonmagnetic spacing layer; a magnetization pinned layer having one or more first layers of a first group of ferromagnetic layers and one or more second layers of a second group of ferromagnetic layers, in which the first layer and the second layer are stacked alternately with a nonmagnetic coupling layer in between, and so antiferromagnetically coupled to each other as to have opposite magnetizations to each other; and an antiferromagnetic layer pinning magnetization orientation in the one or more first and the second layers. The first layers in the first magnetoresistive element are one more in number than that of the one or more second layers. The number of the one or more first layers and that of the one or more second layers in the second magnetoresistive element are equal.
    Type: Application
    Filed: September 13, 2010
    Publication date: March 24, 2011
    Applicant: TDK CORPORATION
    Inventors: Naoki OHTA, Koichi Terunuma, Satoshi Miura, Masanori Sakai, Hiroshi Yamazaki
  • Patent number: 7791838
    Abstract: A magnetic head apparatus is provided which is capable of recording data in a recoding layer having high coercive force with high accuracy without heating. A magnetic recording and reproducing apparatus is also provided which has the magnetic head apparatus. A recording head has: a main magnetic pole; a recording-side front-end shield (a return magnetic pole); a recording-side rear-end shield (a return magnetic pole); a main coil for generating a perpendicular recording magnetic field at the main magnetic pole; and an auxiliary coil for generating a longitudinal alternating current magnetic field having a frequency in the microwave band at the main magnetic pole.
    Type: Grant
    Filed: April 26, 2007
    Date of Patent: September 7, 2010
    Assignee: TDK Corporation
    Inventors: Isamu Sato, Yoshikazu Soeno, Koichi Terunuma, Tetsuya Roppongi, Hiroshi Ikeda
  • Patent number: 7675718
    Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.
    Type: Grant
    Filed: October 27, 2006
    Date of Patent: March 9, 2010
    Assignee: Headway Technologies, Inc.
    Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
  • Patent number: 7506430
    Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.
    Type: Grant
    Filed: October 27, 2006
    Date of Patent: March 24, 2009
    Assignee: Headway Technologies, Inc.
    Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
  • Patent number: 7477491
    Abstract: It has been found that the insertion of a copper laminate within CoFe, or a CoFe/NiFe composite, leads to higher values of CPP GMR and DRA. However, this type of structure exhibits very negative magnetostriction, in the range of high ?10?6 to ?10?5. This problem has been overcome by giving the copper laminates an oxygen exposure treatment When this is done, the free layer is found to have a very low positive magnetostriction constant. Additionally, the value of the magnetostriction constant can be adjusted by varying the thickness of the free layer and/or the position and number of the oxygen treated copper laminates.
    Type: Grant
    Filed: November 7, 2005
    Date of Patent: January 13, 2009
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Kunliang Zhang, Masashi Sano, Koichi Terunuma, Simon Liao, Kochan Ju
  • Patent number: 7403358
    Abstract: A magnetoresistive effective film responds commensurate with an external magnetic field. Magnetic domain-controlling films apply a perpendicular biasing magnetic field to the magnetoresistive effective film. The forefronts of first electrode films constituting a pair of electrode films are overlaid on the magnetoresistive effective film, and the forefront surfaces of the first electrode films are risen at an inner angle of ?1. Second electrode films are overlaid on the first electrode films, and the forefront surfaces of the second electrode films are risen at an inner angle of ?2 smaller than the inner angle ?1.
    Type: Grant
    Filed: September 16, 2005
    Date of Patent: July 22, 2008
    Assignee: TDK Corporation
    Inventors: Koichi Terunuma, Koji Shimazawa, Akifumi Kamijima
  • Patent number: 7311850
    Abstract: In a method of forming a patterned thin film, first, an etching stopper film and a film to be patterned are formed in this order on a base layer. Next, a patterned first film is formed on the film to be patterned. Next, a second film is formed over an entire surface on top of the film to be patterned and the first film. Then, by removing the first film, an etching mask is obtained from the second film formed on the film to be patterned. The film to be patterned is selectively etched through dry etching using the etching mask. A patterned thin film having a groove is thereby obtained.
    Type: Grant
    Filed: October 17, 2002
    Date of Patent: December 25, 2007
    Assignee: TDK Corporation
    Inventors: Akifumi Kamijima, Yoichi Ishida, Koichi Terunuma
  • Publication number: 20070253106
    Abstract: A magnetic head apparatus is provided which is capable of recording data in a recoding layer having high coercive force with high accuracy without heating. A magnetic recording and reproducing apparatus is also provided which has the magnetic head apparatus. A recording head has: a main magnetic pole; a recording-side front-end shield (a return magnetic pole); a recording-side rear-end shield (a return magnetic pole); a main coil for generating a perpendicular recording magnetic field at the main magnetic pole; and an auxiliary coil for generating a longitudinal alternating current magnetic field having a frequency in the microwave band at the main magnetic pole.
    Type: Application
    Filed: April 26, 2007
    Publication date: November 1, 2007
    Applicant: TDK CORPORATION
    Inventors: Isamu Sato, Yoshikazu Soeno, Koichi Terunuma, Tetsuya Roppongi, Hiroshi Ikeda
  • Patent number: 7259940
    Abstract: A pair of domain control layers are disposed on both sides of the track width direction of the MR film so as to be separated from each other such that the MR film is held therebetween, and apply a longitudinal magnetic field to the MR film (free layer). The MR film is flanked by the domain control layers, each including a layer structure constituted by a base layer, a ferromagnetic layer, and a hard magnetic layer. The base layer causes the hard magnetic layer to have a magnetization direction aligning with an in-plane direction, so as to enhance the coercive force of the hard magnetic layer.
    Type: Grant
    Filed: July 13, 2004
    Date of Patent: August 21, 2007
    Assignee: TDK Corporation
    Inventors: Kosuke Tanaka, Koji Shimazawa, Koichi Terunuma, Tomoaki Shimizu
  • Patent number: 7221546
    Abstract: A longitudinal bias magnetic field control layer applies a counter bias magnetic field to a soft magnetic layer that is antiparallel (in opposite direction) to a longitudinal bias magnetic field. A magnitude of the counter bias magnetic field applied to the soft magnetic layer by the longitudinal bias magnetic field control layer is set smaller than that of the longitudinal bias magnetic field at a track center portion of the soft magnetic layer applied by a pair of bias magnetic field applying layers. A substantial longitudinal bias magnetic field is substantially applied to the soft magnetic layer in the same direction as that of the longitudinal bias magnetic field, and a magnitude of the substantial longitudinal bias magnetic field is maximum at both end portions of the soft magnetic layer and is weakened at the center portion of the soft magnetic layer.
    Type: Grant
    Filed: April 28, 2004
    Date of Patent: May 22, 2007
    Assignee: TDK Corporation
    Inventors: Koichi Terunuma, Koji Shimazawa, Yoshihiro Tsuchiya
  • Patent number: 7193822
    Abstract: At both end portions of at least a soft magnetic layer of a magneto-resistive effect film, a pair of bias magnetic field applying layers are disposed for applying a longitudinal bias magnetic field to the soft magnetic layer via magnetic underlayers. Further, mutual lattice point-to-point distances in the plane where each magnetic underlayer and the corresponding bias magnetic field applying layer are mated, are substantially equalized to each other. Therefore, a coercive force Hc in an in-plane direction (direction parallel to a film surface) of each bias magnetic field applying layer can be maintained at a high level so that even when further gap narrowing or track narrowing is aimed, the bias magnetic field applying layers can act to apply an effective bias magnetic field, i.e. can act to suppress occurrence of the Barkhausen noise.
    Type: Grant
    Filed: June 7, 2004
    Date of Patent: March 20, 2007
    Assignee: TDK Corporation
    Inventors: Tomoaki Shimizu, Koji Shimazawa, Kosuke Tanaka, Koichi Terunuma
  • Publication number: 20070039166
    Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.
    Type: Application
    Filed: October 27, 2006
    Publication date: February 22, 2007
    Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
  • Publication number: 20070041124
    Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.
    Type: Application
    Filed: October 27, 2006
    Publication date: February 22, 2007
    Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
  • Patent number: 7136263
    Abstract: A thin-film magnetic head comprises a magnetoresistive film, a pair of magnetic domain control layers for applying a bias magnetic field to the magnetoresistive film, a pair of electrode layers for supplying a current to the magnetoresistive film, first and second shield layers for shielding the magnetoresistive film, a first insulating layer disposed between the magnetoresistive film and magnetic domain control layer and the first shield layer, and a second insulating layer disposed between the magnetoresistive film and electrode layer and the second shield layer. The shield layers have a distance therebetween shorter at a position where the electrode layer and magnetic domain control layer are laminated than that at a position where the magnetoresistive film is located.
    Type: Grant
    Filed: December 5, 2003
    Date of Patent: November 14, 2006
    Assignee: TDK Corporation
    Inventors: Kosuke Tanaka, Koji Shimazawa, Koichi Terunuma
  • Patent number: 7134184
    Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.
    Type: Grant
    Filed: November 12, 2003
    Date of Patent: November 14, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
  • Patent number: 7126794
    Abstract: Provided are a thin film magnetic head capable of inhibiting an excessive temperature rise while reducing its size in accordance with a higher recording density, and obtaining a higher read output, a method of manufacturing the same, and a magnetic disk drive using the thin film magnetic head. A heat dissipation layer for transferring heat generated in a magnetic transducer film to outside is disposed adjacent to the magnetic transducer film on a side, the side being opposite to a side facing a recording medium. In a gap layer for electrically insulating between the magnetic transducer film and a pair of shield layers, a portion of the gap layer in contact with an end surface of the magnetic transducer film on a side, the side being opposite to a side facing the recording medium is formed so as to have a thin thickness ranging from 2 nm to 30 nm inclusive.
    Type: Grant
    Filed: April 8, 2003
    Date of Patent: October 24, 2006
    Assignee: TDK Corporation
    Inventors: Yoshihiro Kudo, Koichi Terunuma
  • Patent number: 7107667
    Abstract: A first and a second longitudinal bias-applying films are formed via a first mask at both sides of a magnetoresistive effective element film so that the difference in surface level between the magnetoresistive effective element film and the first and the second longitudinal bias-applying films is set within ±20 nm. Then, a first and a second electrode films are formed so as to cover edge portions of the magnetoresistive effective element film and the first and the second longitudinal bias-applying films.
    Type: Grant
    Filed: April 20, 2004
    Date of Patent: September 19, 2006
    Assignee: TDK Corporation
    Inventors: Noriyuki Ito, Kosuke Tanaka, Koichi Terunuma
  • Patent number: 7088560
    Abstract: Provided are a thin film magnetic head capable of inhibiting an excessive temperature rise while reducing its size in accordance with a higher recording density, and obtaining a higher read output, a method of manufacturing the same, and a magnetic disk drive using the thin film magnetic head. A heat dissipation layer for transferring heat generated in a magnetic transducer film to outside is disposed adjacent to the magnetic transducer film on a side, the side being opposite to a side facing a recording medium. In a gap layer for electrically insulating between the magnetic transducer film and a pair of shield layers, a portion of the gap layer in contact with an end surface of the magnetic transducer film on a side, the side being opposite to a side facing the recording medium is formed so as to have a thin thickness ranging from 2 nm to 30 nm inclusive.
    Type: Grant
    Filed: September 30, 2005
    Date of Patent: August 8, 2006
    Assignee: TDK Corporation
    Inventors: Yoshihiro Kudo, Koichi Terunuma
  • Patent number: 7082673
    Abstract: A magnetoresisive device comprises: an MR element having two surfaces that face toward opposite directions and two side portions that face toward opposite directions; two bias field applying layers that are located adjacent to the side portions of the MR element and apply a longitudinal bias magnetic field to the MR element; and two electrode layers that are located adjacent to one of the surfaces of each of the bias field applying layers and feed a sense current to the MR element. The electrode layers overlap the one of the surfaces of the MR element. The magnetoresistive device further comprises two nonconductive layers that are located between the one of the surfaces of the MR element and the two electrode layers and located in two regions that include ends of the MR element near the side portions thereof, the two regions being parts of the region in which the electrode layers face toward the one of the surfaces of the MR element.
    Type: Grant
    Filed: September 26, 2003
    Date of Patent: August 1, 2006
    Assignee: TDK Corporation
    Inventors: Koji Shimazawa, Koichi Terunuma
  • Patent number: 7065859
    Abstract: A first magnetic film is formed in a primary pattern which is larger than its definitive pattern and of which edges are located within frames to be used in a frame-plating method for the second magnetic film after forming the first pole portion and the gap film. Then, the second magnetic film is formed by the frame-plating method, and the first magnetic film is etched into the definitive pattern through the second magnetic film as a mask.
    Type: Grant
    Filed: December 3, 2003
    Date of Patent: June 27, 2006
    Assignee: TDK Corporation
    Inventors: Koichi Terunuma, Tetsuya Mino, Katsuya Kanakubo, Noriyuki Ito