Patents by Inventor Kazusuke Yamanaka

Kazusuke Yamanaka 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: 7157162
    Abstract: A magnetic recording medium having a substrate, an under-layer formed on the substrate, a magnetic layer formed on the substrate and a protective layer formed on the magnetic layer. The magnetic layer comprises Co, Cr and Pt with a thickness being from 10 nm to 22 nm. Further, a coercivity of the magnetic layer is not less than 2000 Oe, and a fluctuation field of magnetic viscosity at a field strength equal to remanence coercivity or coercivity is not less than 30 Oe.
    Type: Grant
    Filed: January 18, 2005
    Date of Patent: January 2, 2007
    Assignee: Hitachi Global Storage Technologies Japan, Ltd.
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Publication number: 20050123806
    Abstract: A magnetic recording medium having a substrate, an under-layer formed on the substrate, a magnetic layer formed on the substrate and a protective layer formed on the magnetic layer. The magnetic layer comprises Co, Cr and Pt with a thickness being from 10 nm to 22 nm. Further, a coercivity of the magnetic layer is not less than 2000 Oe, and a fluctuation field of magnetic viscosity at a field strength equal to remanence coercivity or coercivity is not less than 30 Oe.
    Type: Application
    Filed: January 18, 2005
    Publication date: June 9, 2005
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Patent number: 6846577
    Abstract: An ferromagnetic thin film is used to provide a magnetic recording medium whose noise is low and whose S/N value is high. The ferromagnetic thin film as the magnetic film of the magnetic recording medium is such that the fluctuation field of magnetic viscosity at 25° C. at the field strength equal to remanence coercivity or coercivity is not less than 15 oersteds and the coercivity is not less than 2000 oersteds.
    Type: Grant
    Filed: March 13, 2003
    Date of Patent: January 25, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Patent number: 6706426
    Abstract: To obtain a large capacity magnetic recording medium capable of recording at a super high density of 3 Gbit or more per one square inch and a magnetic storage apparatus, a magnetic recording medium is prepared by disposing orientation control layers 31, 31′ having at least a B2 (CsCl) structure on a substrate 30, disposing a first underlayer comprising Cr and a second underlayer containing at least one element selected from Cr, Nb, Mo, Ta, W and Ti and having a lattice constant greater than that of the first underlayer and then forming a magnetic layer comprising Co as the main ingredient.
    Type: Grant
    Filed: March 10, 2000
    Date of Patent: March 16, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Tomoo Yamamoto, Akira Ishikawa, Kazusuke Yamanaka, Atsushi Nakamura
  • Publication number: 20030170497
    Abstract: An ferromagnetic thin film is used to provide a magnetic recording medium whose noise is low and whose S/N value is high. The ferromagnetic thin film as the magnetic film of the magnetic recording medium is such that the fluctuation field of magnetic viscosity at 25° C. at the field strength equal to remanence coercivity or coercivity is not less than 15 oersteds and the coercivity is not less than 2000 oersteds.
    Type: Application
    Filed: March 13, 2003
    Publication date: September 11, 2003
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Patent number: 6613428
    Abstract: A thin film magnetic recording medium including a magnetic layer having a fluctuation field defined as S/Xirr, where S is magnetic viscosity and Xirr is irreversible susceptibility Xirr. The fluctuation field of the magnetic layer is not less than 15 oersteds.
    Type: Grant
    Filed: May 7, 2001
    Date of Patent: September 2, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Patent number: 6572988
    Abstract: A magnetic recording medium has a magnetic recording film in which the magnitude of saturation magnetization Ms(T=5° K) at 5° K and magnitude of saturation magnetization Ms(T=300° K) at 300° K satisfy: Ms(T=300° K)/Ms(T=5° K)≧0.75. The recording medium enables the high-density recording, and a magnetic recording apparatus using this recording medium can yield a sufficiently high reproduction signal level within the operating temperature range of the apparatus.
    Type: Grant
    Filed: August 30, 1999
    Date of Patent: June 3, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Nobuyuki Inaba, Kazuetsu Yoshida, Kazusuke Yamanaka, Fumiyoshi Kirino, Masaaki Futamoto
  • Patent number: 6310748
    Abstract: A ferromagnetic thin film is used to provide a magnetic recording medium whose noise is low and whose S/N is high. The ferromagnetic thin film as the magnetic film of the magnetic recording medium is such that the fluctuation field of magnetic viscosity at 25° C. at the field strength equal to remanence coercivity or coercivity is not less than 15 oersteds and the coercivity is not less than 2000 oersteds.
    Type: Grant
    Filed: August 31, 1995
    Date of Patent: October 30, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Publication number: 20010021465
    Abstract: A thin film magnetic recording medium including a magnetic layer having a fluctuation field defined as S/Xirr, where S is magnetic viscosity and Xirr is irreversible susceptibility Xirr. The fluctuation field of the magnetic layer is not less than 15 oersteds.
    Type: Application
    Filed: May 7, 2001
    Publication date: September 13, 2001
    Inventors: Kazusuke Yamanaka, Tomoo Yamamoto, Yuzuru Hosoe, Nobuyuki Inaba, Yasutaro Uesaka, Masaaki Futamoto, Yoshibumi Matsuda, Kenji Furusawa, Shinji Narishige
  • Patent number: 6177208
    Abstract: A magnetic recording system high in S/N and low in bit error rate, capable of carrying out writing and reading of high recording density of at least 1 gigabit per 1 square inch and high in reliability can be realized by making the magnetic layer of the magnetic recording medium from a mixture comprising at least one non-magnetic compound selected from the group consisting of oxides and nitrides and a magnetic material comprising Co and Pt as main components and specifying the molar ratio of Pt to Co in the magnetic layer, and employing a magnetoresistive read back magnetic recording head.
    Type: Grant
    Filed: May 25, 1999
    Date of Patent: January 23, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Tomoo Yamamoto, Nobuyuki Inaba, Masukazu Igarashi, Masaaki Futamoto, Yuzuru Hosoe, Ichiro Tamai, Emi Mangyo, Kazusuke Yamanaka
  • Patent number: 6083599
    Abstract: A perpendicular magnetic recording medium is provided by using a ferromagnetic polycrystalline thin film having main components of cobalt and chromium in which the coercivity is 1500 oersted or more and the fluctuation field of magnetic viscosity is 30 oersted or more; the film thickness is controlled within a range from 30 nm to 100 nm. A perpendicular magnetic recording medium with low noise and high output which is suited for high density recording can be obtained and a large capacity magnetic recording and reproducing apparatus can be provided by using this medium.
    Type: Grant
    Filed: September 3, 1997
    Date of Patent: July 4, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Yoshiyuki Hirayama, Masaaki Futamoto, Yukio Honda, Kazusuke Yamanaka, Kenya Ito
  • Patent number: 5919581
    Abstract: A magnetic recording system high in S/N and low in bit error rate, capable of carrying out writing and reading of high recording density of at least 1 gigabit per 1 square inch and high in reliability can be realized by making the magnetic layer of the magnetic recording medium from a mixture comprising at least one non-magnetic compound selected from the group consisting of oxides and nitrides and a magnetic material comprising Co and Pt as main components and specifying the molar ratio of Pt to Co in the magnetic layer, and employing a magnetoresistive read back magnetic recording head.
    Type: Grant
    Filed: June 25, 1996
    Date of Patent: July 6, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Tomoo Yamamoto, Nobuyuki Inaba, Masukazu Igarashi, Masaaki Futamoto, Yuzuru Hosoe, Ichiro Tamai, Emi Mangyo, Kazusuke Yamanaka
  • Patent number: 5686177
    Abstract: A magnetic recording medium having an improved S/N is provided by using a ferromagnetic metal thin film having a mean value of a fluctuation field of magnetic viscosithy measured at 25.degree. C. in a region in which an applied magnetic field strength is 0.8 to 1.2 times as large as a remanence coercivity, of between 15 Oersteads and 30 Oersteads, and preferably a coercivity of between 700 Oersteads and 2000 Oersteads.
    Type: Grant
    Filed: August 15, 1994
    Date of Patent: November 11, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Kazusuke Yamanaka, Hideo Kusada, Toyoji Okuwaki
  • Patent number: 4773740
    Abstract: An electrochromic display device which comprises a display electrode comprising a transparent substrate, a transparent electrode formed on an inner surface of the transparent substrate and an electrochromic material layer for display made of tungsten oxide and formed on the transparent electrode; a counter electrode comprising a substrate, a conductive layer formed on an inner surface of the substrate and an activated carbon fiber material; and a spacer provided between the display electrode and the counter electrode with their inner surfaces facing each other to define, between them, an electrolyte chamber, which is filled with an electrolyte comprising a lithium salt and at least one of the tertiary alkyl ammonium salts and quarternary alkyl ammonium slats dissolved in a non-aqueous medium containing a small amount of water, which device has increased original injected charge which can last for a long time.
    Type: Grant
    Filed: October 21, 1987
    Date of Patent: September 27, 1988
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Akira Kawakami, Toshikatsu Manabe, Tsunemi Ohiwa, Shuichi Wada, Kenichi Yokoyama, Saburo Nonogaki, Kazusuke Yamanaka
  • Patent number: 4411497
    Abstract: Disclosed is an electrochromic display element having a counter electrode comprised of a sintered material prepared by sintering an atomized material comprising as main components a powder of Sn[Fe(CN).sub.6 ], MnK[Fe(CN).sub.6 ], NiK[Fe(CN).sub.6 ], amorphous Fe.sub.2 (WO.sub.4).sub.3, amorphous FeWO.sub.4, amorphous Mn.sub.2 (WO.sub.4).sub.3 or amorphous MnWO.sub.4 and a powder of carbon. This electrochromic display element is characterized in that no substantial non-uniform brightness is observed among colored segments.
    Type: Grant
    Filed: February 11, 1981
    Date of Patent: October 25, 1983
    Assignee: Hitachi, Ltd.
    Inventors: Kazusuke Yamanaka, Shouji Mochizuki