Patents by Inventor Nobuyuki Ishiwata

Nobuyuki Ishiwata 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: 20040190198
    Abstract: By inserting a first antistripping layer comprising a first non-magnetic layer 22 and a first conductive layer 23 between a first magnetic layer 16 and a magnetic separation layer 13, adhesion between the first conductive layer 23 and the magnetic separation layer 13 is improved to prevent the first magnetic layer 16 from stripping. In addition, by inserting a second antistripping layer comprising a second non-magnetic layer 24 and a second conductive layer 25 between a second magnetic layer 21 and a magnetic gap layer 17, adhesion between the second conductive layer 24 and the magnetic gap layer 17 is improved to prevent the second magnetic layer 25 from stripping.
    Type: Application
    Filed: March 31, 2004
    Publication date: September 30, 2004
    Inventors: Hiroaki Honjo, Tsutomu Ishi, Mikiko Saito, Shinsaku Saito, Tamaki Toba, Yoshihiro Nonaka, Kazuhiko Hayashi, Nobuyuki Ishiwata
  • Patent number: 6798626
    Abstract: A magnetoresistive effect element which is easy to manufacture and in which a sense current is prevented from bypassing a barrier layer is provided. Also provided are a method for manufacturing the element and a magnetic recording apparatus utilizing the element. This magnetoresistive effect element utilizes an MTJ film which comprises, for forming its basic structure, a free layer, a barrier layer, a pinned layer and a pinning layer, wherein an oxide or a nitride layer is formed by oxidizing or nitriding metallic materials constituting the pinned layer and pinning layer.
    Type: Grant
    Filed: February 3, 2003
    Date of Patent: September 28, 2004
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Eizo Fukami, Kiyokazu Nagahara, Hiroaki Honjou, Shinsaku Saitoh
  • Patent number: 6795271
    Abstract: A recording head is a magnetic head in which ends on one side of opposed first and second magnetic cores form a recording gap, said other ends form a magnetic joint, coils insulated by an insulating material are provided between said first and second magnetic cores, magnetic fluxes of said first and second magnetic cores excited by said coils leak from said recording gap so that recording onto a recording medium is carried out. In said recording head, a distance from said end of said recording gap close to said magnetic medium to a contact point of said magnetic joint (hereinafter, yoke length) is not more than 20 &mgr;m. A magnetic recording/reproduction apparatus has this head.
    Type: Grant
    Filed: December 27, 2000
    Date of Patent: September 21, 2004
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Hiroaki Honjo, Tamaki Toba, Shinsaku Saito, Yoshihiro Nonaka, Tsutomu Ishi, Mikiko Saito, Keishi Ohashi
  • Patent number: 6791794
    Abstract: By inserting a first antistripping layer comprising a first non-magnetic layer 22 and a first conductive layer 23 between a first magnetic layer 16 and a magnetic separation layer 13, adhesion between the first conductive layer 23 and the magnetic separation layer 13 is improved to prevent the first magnetic layer 16 from stripping. In addition, by inserting a second antistripping layer comprising a second non-magnetic layer 24 and a second conductive layer 25 between a second magnetic layer 21 and a magnetic gap layer 17, adhesion between the second conductive layer 24 and the magnetic gap layer 17 is improved to prevent the second magnetic layer 25 from stripping.
    Type: Grant
    Filed: April 1, 2002
    Date of Patent: September 14, 2004
    Assignee: NEC Corporation
    Inventors: Hiroaki Honjo, Tsutomu Ishi, Mikiko Saito, Shinsaku Saito, Tamaki Toba, Yoshihino Nonaka, Kazuhiko Hayashi, Nobuyuki Ishiwata
  • Publication number: 20040174641
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Application
    Filed: March 18, 2004
    Publication date: September 9, 2004
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokasu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 6780530
    Abstract: A magnetic material includes a main component expressed by a general formula CoNiFeX, wherein X is at least one element selected from the group consisting of Cr, Ti, V, Ru, Rh, Pd, Os, Ir and Pt, and wherein weight percentages a, b, c and d of Co, Ni, Fe and X contents, respectively, in the main component are such that 40%≦a≦10%, 5%≦b≦20%, 10%≦c≦30%, and 0%<d≦10%.
    Type: Grant
    Filed: May 5, 2003
    Date of Patent: August 24, 2004
    Assignee: NEC Corporation
    Inventors: Mikiko Saito, Nobuyuki Ishiwata, Tsutomu Ishi, Hiroaki Honjo, Tamaki Toba, Shinsaku Saito, Yoshihiro Nonaka
  • Publication number: 20040134877
    Abstract: In a magnetoresistance apparatus including a first functional layer and a second functional layer magnetically connected to the first functional layer, an overlapping ratio of the second functional layer onto the first functional layer is approximately 0 to 10 percent.
    Type: Application
    Filed: January 5, 2004
    Publication date: July 15, 2004
    Applicant: TDK CORPORATION
    Inventors: Nobuyuki Ishiwata, Shigeru Mori, Kiyokazu Nagahara, Tsutomu Ishi, Kunihiko Ishihara, Eizo Fukami, Masafumi Nakada
  • Patent number: 6754051
    Abstract: In a spin valve type transducer including two magnetic shield layers, a patterned magnetoresistance element is in direct contact with one of the magnetic shield layers. A permanent magnet layer and an electrode layer are formed on the sides of the patterned magnetoresistance element.
    Type: Grant
    Filed: May 28, 2003
    Date of Patent: June 22, 2004
    Assignee: TDK Corporation
    Inventor: Nobuyuki Ishiwata
  • Patent number: 6747853
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Grant
    Filed: May 21, 2003
    Date of Patent: June 8, 2004
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 6718621
    Abstract: In a production process of an MR head using the tunnel junction film basically consisting of a free layer, a barrier layer, and a pinned layer, the resistance between the free layer and the pined layer reduced beforehand and increased afterward up to a resistance value necessary when actually used. While the resistance between the free layer and the pinned layer is low, current can easily flow, suppressing charge up, thus preventing insulation destruction of the barrier layer. This significantly increases a production yield of a recording/reproduction head using a ferromagnetic tunnel junction element.
    Type: Grant
    Filed: May 9, 2000
    Date of Patent: April 13, 2004
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Eizo Fukami, Kiyokazu Nagahara, Hiroaki Honjo, Shinsaku Saitoh
  • Patent number: 6687082
    Abstract: A magnetic head and a manufacturing method of the magnetic head and a magnetic recording and reproducing apparatus used this head, in which the following problem is solved, are provided. A plated film realizing large saturation magnetization Bs about 2T can not realize a high resistivity at the same time, therefore, when this plated film is applied to a magnetic head, the high frequency characteristic is deteriorated. This problem is solved at the present invention. Further, the present invention provides a magnetic head that is low cost and has large saturation magnetization Bs, and has a excellent high frequency characteristic suitable for a high density recording.
    Type: Grant
    Filed: October 2, 2000
    Date of Patent: February 3, 2004
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi, Mikiko Saito, Hiroaki Honjo, Shinsaku Saito, Tamaki Toba, Yoshihiro Nonaka
  • Patent number: 6671140
    Abstract: A first magnetic layer (3) is laminated on a magnetic yoke film (2) forming a closed magnetic circuit containing a magnetic gap so as to be magnetically coupled to the magnetic yoke film (2), and a magnetic separation layer (4), a second magnetic layer (5) and an antiferromagnetic layer (6) are laminated on the first magnetic layer (3). Further, a pair of electrodes (1, 7) are formed so that the laminate comprising the above layers is sandwiched between the electrodes. A permanent magnet film 8 is disposed to apply a bias magnetic field to the first magnetic layer (3). The magnetic separation layer (4) is formed of an insulator.
    Type: Grant
    Filed: May 23, 2000
    Date of Patent: December 30, 2003
    Assignee: NEC Corporation
    Inventor: Nobuyuki Ishiwata
  • Publication number: 20030197981
    Abstract: In a spin value type transducer including two magnetic shield layers, a patterned magnetoresistance element is in direct contact with one of the magnetic shield layers. A permanent magnet layer and an electrode layer are formed on the sides of the patterned magnetoresistance element.
    Type: Application
    Filed: May 28, 2003
    Publication date: October 23, 2003
    Applicant: TDK Corporation
    Inventor: Nobuyuki Ishiwata
  • Publication number: 20030194581
    Abstract: A magnetic material includes a main component expressed by a general formula CoNiFeX, wherein X is at least one element selected from the group consisting of Cr, Ti, V, Ru, Rh, Pd, Os, Ir and Pt, and wherein weight percentages a, b, c and d of Co, Ni, Fe and X contents, respectively, in the main component are such that 40%≦a≦10%, 5%≦b≦20%, 10%≦c≦30%, and 0%<d≦10%.
    Type: Application
    Filed: May 5, 2003
    Publication date: October 16, 2003
    Applicant: NEC CORPORATION
    Inventors: Mikiko Saito, Nobuyuki Ishiwata, Tsutomu Ishi, Hiroaki Honjo, Tamaki Toba, Shinsaku Saito, Yoshihiro Nonaka
  • Publication number: 20030193762
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Application
    Filed: May 21, 2003
    Publication date: October 16, 2003
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 6624987
    Abstract: A magnetoresistive effect head which is easy to manufacture and in which a sense current is prevented from bypassing a barrier layer is provided. Also provided are a method for manufacturing the head and a magnetic recording apparatus utilizing the head. This magnetoresistive effect head utilizes an MTJ film which comprises, for forming its basic structure, a free layer, a barrier layer, a pinned layer and a pinning layer, wherein an oxide or a nitride layer is formed by oxidizing or nitriding metallic materials constituting the pinned layer and pinning layer.
    Type: Grant
    Filed: May 31, 2000
    Date of Patent: September 23, 2003
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Eizo Fukami, Kiyokazu Nagahara, Hiroaki Honjou, Shinsaku Saitoh
  • Publication number: 20030151859
    Abstract: A magnetoresistive effect element which is easy to manufacture and in which a sense current is prevented from bypassing a barrier layer is provided. Also provided are a method for manufacturing the element and a magnetic recording apparatus utilizing the element. This magnetoresistive effect element utilizes an MTJ film which comprises, for forming its basic structure, a free layer, a barrier layer, a pinned layer and a pinning layer, wherein an oxide or a nitride layer is formed by oxidizing or nitriding metallic materials constituting the pinned layer and pinning layer.
    Type: Application
    Filed: February 3, 2003
    Publication date: August 14, 2003
    Applicant: NEC CORPORATION
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Eizo Fukami, Kiyokazu Nagahara, Hiroaki Honjou, Shinsaku Saitoh
  • Patent number: 6597543
    Abstract: A thin-film magnetic head is constituted by forming a lower shielding layer, a read gap layer holding an MR magnetosensitive element, a common pole layer, and a write gap layer in order on an insulating substrate, forming a first flattening layer, a coil pattern layer, and a second flattening layer laminated in order on the write gap layer excluding the vicinity of an ABS plane, and forming an upper pole layer on the write gap layer and the second flattening layer nearby an ABS plane. A concave portion is formed on the common pole layer at a position separated from the ABS plane, the concave portion is filled with a nonmagnetic body, and the gap depth between the upper pole layer and the common pole layer is determined by the concave portion.
    Type: Grant
    Filed: May 24, 1999
    Date of Patent: July 22, 2003
    Assignee: TDK Corporation
    Inventors: Shinsaku Saitho, Haruo Urai, Nobuyuki Ishiwata, Kiyotaka Shimabayashi, Yoshihiro Nonaka, Tamaki Toba
  • Patent number: 6592811
    Abstract: A magnetic material includes a main component expressed by a general formula CoNiFeX, wherein X is at least one element selected from the group consisting of Cr, TI, V, Ru, Rh, Os, Ir and Pt, and wherein weight percentages a, b, c and d of Co, Ni, Fe and X contents, respectively, in the main component are such that 40%≦a≦75%, 5%≦b≦20%, 10%≦c≦30%, and 0%≦d≦10%.
    Type: Grant
    Filed: October 5, 2000
    Date of Patent: July 15, 2003
    Assignee: NEC Corporation
    Inventors: Mikiko Saito, Nobuyuki Ishiwata, Tsutomu Ishi, Hiroaki Honjo, Tamaki Toba, Shinsaku Saito, Yoshihiro Nonaka
  • Publication number: 20030128480
    Abstract: To accurately decrease the gap depth between an upper pole layer and a lower pole layer and the front-end portion width of the upper pole layer.
    Type: Application
    Filed: February 27, 2003
    Publication date: July 10, 2003
    Inventors: Shinsaku Saitho, Haruo Urai, Nobuyuki Ishiwata, Kiyotaka Shimabayashi, Yoshihiro Nonaka, Tamaki Toba