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).

  • Patent number: 7046487
    Abstract: A first magnetic shielding film is disposed on one surface of a magnetoresistive effective film in a thickness direction thereof, and a second magnetic shielding film is disposed on the other surface of the magnetoresistive effective film in said thickness direction thereof. The antiferromagnetic films are disposed in between the first magnetic shielding film and the second magnetic shielding film, adjacent to and bonded through exchange interaction with at least one of the first magnetic shielding film and the second magnetic shielding film.
    Type: Grant
    Filed: September 23, 2003
    Date of Patent: May 16, 2006
    Assignee: TDK Corporation
    Inventor: Koichi Terunuma
  • Patent number: 7029770
    Abstract: An exchange-coupled film has a ferromagnetic layer sandwich comprising a first ferromagnetic layer containing a ferromagnetic material of the body-centered cubic structure and a pair of second ferromagnetic layers containing a ferromagnetic material of the face-centered cubic structure and formed on respective sides of the first ferromagnetic layer; and an antiferromagnetic layer containing a disordered alloy and formed on one of the second ferromagnetic layers. It yields sufficient exchange coupling energy even in smaller thickness of the antiferromagnetic layer than before, whereby it becomes feasible to decrease the thickness of the exchange-coupled film.
    Type: Grant
    Filed: August 5, 2003
    Date of Patent: April 18, 2006
    Assignee: TDK Corporation
    Inventors: Koji Shimazawa, Yoshihiro Tsuchiya, Koichi Terunuma
  • Patent number: 7027271
    Abstract: A magnetoresisive device comprises an MR element, bias field applying layers located adjacent to the side portions of the MR element, and two electrode layers that feed a sense current to the MR element. The electrode layers overlap one of the surfaces of the MR element. The total overlap amount of the two electrode layers is smaller than 0.3 ?m. The MR element is a spin-valve GMR element. The MR element incorporates a base layer, a free layer, a spacer layer, a pinned layer, an antiferromagnetic layer, and a cap layer that are stacked in this order. The pinned layer includes a nonmagnetic spacer layer, and two ferromagnetic layers that sandwich this spacer layer.
    Type: Grant
    Filed: July 25, 2001
    Date of Patent: April 11, 2006
    Assignee: TDK Corporation
    Inventors: Kenji Inage, Yoshihiro Kudo, Ken-ichi Takano, Koichi Terunuma, Yuzuru Iwai
  • Publication number: 20060061919
    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: Application
    Filed: November 7, 2005
    Publication date: March 23, 2006
    Inventors: Min Li, Kunliang Zhang, Masashi Sano, Koichi Terunuma, Simon Liao, Kochan Ju
  • Patent number: 6998150
    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: March 12, 2003
    Date of Patent: February 14, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Kunliang Zhang, Masashi Sano, Koichi Terunuma, Simon Liao, Kochan Ju
  • Publication number: 20060028771
    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: Application
    Filed: September 30, 2005
    Publication date: February 9, 2006
    Applicant: TDK Corporation
    Inventors: Yoshihiro Kudo, Koichi Terunuma
  • Publication number: 20060007604
    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: Application
    Filed: September 16, 2005
    Publication date: January 12, 2006
    Applicant: TDK Corporation
    Inventors: Koichi Terunuma, Koji Shimazawa, Akifumi Kamijima
  • Patent number: 6982855
    Abstract: An MR element includes a free layer. Hard magnetic layers are placed on both sides of the MR element and apply a bias magnetic field to the free layer. A pair of electrode layers are placed as spaced from each other, and supplies a sense current to the free layer. Layer structures are placed between portions overlapping with the respective electrode layers in the ambilateral regions of the free layer, and the electrode layers. Each layer structure includes a nonmagnetic layer, a ferromagnetic layer, and an antiferromagnetic layer. A direction of magnetization of the ferromagnetic layer is fixed by the antiferromagnetic layer, and a magnetic thickness of the ferromagnetic layer is set greater than that of the free layer.
    Type: Grant
    Filed: May 12, 2003
    Date of Patent: January 3, 2006
    Assignee: TDK Corporation
    Inventors: Koji Shimazawa, Yoshihiro Tsuchiya, Koichi Terunuma
  • Patent number: 6947261
    Abstract: Provided are a thin film magnetic head and a method of manufacturing the same, which can prevent an output decrease without impairment of productivity and other characteristics, while adapting to an increase in a recording density. In the thin film magnetic head, an MR film is sandwiched in between first and second gap films having electrical insulating properties, which are sandwiched in between first and second shield layers. The first shield layer has an inner layer and an outer layer laminated in order from the MR film, and the second shield layer has an inner layer and an outer layer laminated in order from the MR film. The respective inner layers of the first and second shield layers have hardness higher than that of the respective outer layers thereof so as to prevent the first and second shield layers from deforming.
    Type: Grant
    Filed: October 26, 2001
    Date of Patent: September 20, 2005
    Assignee: TDK Corporation
    Inventor: Koichi Terunuma
  • Patent number: 6927950
    Abstract: A read head comprises an MR element, two bias field applying layers, and two conductive layers. The two bias field applying layers are adjacent to both side portions of the MR element, and apply a bias magnetic field to the MR element along the longitudinal direction. The two conductive layers feed a sense current to the MR element, each of the conductive layers being disposed to be adjacent to one of surfaces of each of the bias field applying layers and to overlap one of surfaces of the MR element. The conductive layers are each made of a gold alloy having a resistivity of less than 22 ??·cm and a hardness as high as or higher than the hardness of a material used for making the bias field applying layers.
    Type: Grant
    Filed: July 12, 2002
    Date of Patent: August 9, 2005
    Assignee: TDK Corporation
    Inventors: Noriyuki Ito, Kosuke Tanaka, Koichi Terunuma
  • Publication number: 20050099739
    Abstract: As track widths in magnetic read heads grow smaller, the spacing between the bias magnets grows less so their effect extends further and further into the free layer. This can be reduced by means of a bias cancellation layer but at the cost of increased edge sensitivity. This problem 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: November 12, 2003
    Publication date: May 12, 2005
    Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
  • Publication number: 20050018367
    Abstract: A longitudinal bias magnetic field control layer is provided for applying to a soft magnetic layer a counter bias magnetic field 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. Through subtraction between the longitudinal bias magnetic field and the counter bias magnetic field, 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: Application
    Filed: April 28, 2004
    Publication date: January 27, 2005
    Applicant: TDK CORPORATION
    Inventors: Koichi Terunuma, Koji Shimazawa, Yoshihiro Tsuchiya
  • Publication number: 20050013063
    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: Application
    Filed: July 13, 2004
    Publication date: January 20, 2005
    Applicant: TDK CORPORATION
    Inventors: Kosuke Tanaka, Koji Shimazawa, Koichi Terunuma, Tomoaki Shimizu
  • Publication number: 20040264066
    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: Application
    Filed: June 7, 2004
    Publication date: December 30, 2004
    Applicant: TDK CORPORATION
    Inventors: Tomoaki Shimizu, Koji Shimazawa, Kosuke Tanaka, Koichi Terunuma
  • Publication number: 20040223268
    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: Application
    Filed: April 20, 2004
    Publication date: November 11, 2004
    Applicant: TDK Corporation
    Inventors: Noriyuki Ito, Kosuke Tanaka, Koichi Terunuma
  • Publication number: 20040179311
    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: Application
    Filed: March 12, 2003
    Publication date: September 16, 2004
    Applicant: Headway Technologies, Inc.
    Inventors: Min Li, Kunliang Zhang, Masashi Sano, Koichi Terunuma, Simon Liao, Kochan Ju
  • Publication number: 20040125513
    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: Application
    Filed: December 5, 2003
    Publication date: July 1, 2004
    Applicant: TDK CORPORATION
    Inventors: Kosuke Tanaka, Koji Shimazawa, Koichi Terunuma
  • Patent number: 6757142
    Abstract: A MR element with a magnetic sensing region and outside regions thereof which locate outside the magnetic sensing region along a track width direction, includes a multi-layered structure with an anti-ferromagnetic thin-film layer, a first ferromagnetic thin-film layer constituted by a single layer of ferromagnetic material or by multi layers of ferromagnetic material, a non-magnetic metal thin-film layer and a second ferromagnetic thin-film layer constituted by a single layer of ferromagnetic material or by multi layers of ferromagnetic material which are sequentially formed on a substrate. The all layers in the multi-layered structure exist in the magnetic sensing region, and at least the anti-ferromagnetic thin-film layer with its initial thickness exists in the outside regions.
    Type: Grant
    Filed: July 8, 1999
    Date of Patent: June 29, 2004
    Assignee: TDK Corporation
    Inventor: Koichi Terunuma
  • Patent number: 6751070
    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: May 24, 2002
    Date of Patent: June 15, 2004
    Assignee: TDK Corporation
    Inventors: Noriyuki Ito, Kosuke Tanaka, Koichi Terunuma
  • Publication number: 20040107563
    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: Application
    Filed: December 3, 2003
    Publication date: June 10, 2004
    Applicant: TDK CORPORATION
    Inventors: Koichi Terunuma, Tetsuya Mino, Katsuya Kanakubo, Noriyuki Ito