Patents by Inventor Takaaki Shirakura

Takaaki Shirakura 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: 6989535
    Abstract: To provide an atomic force microscopy which allows the measurement of the configuration of a surface being measured by using the phenomenon observed between the surface being measured and a probe approaching thereto at very fine distance. By selecting the material of the tip surface of said probe such that the surface energy of said probe tip becomes less than the interface energy between the tip surface and the surface being measured, thereby the surface configuration of soft body, or soft fouling adhered to the body surface can be measured. A method of measuring the surface configuration and a method of producing magnetic recording medium using the same are also provided.
    Type: Grant
    Filed: December 4, 2002
    Date of Patent: January 24, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Tani, Yoko Ogawa, Masanori Inoue, Takaaki Shirakura, Koji Sonoda
  • Patent number: 6627253
    Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. and 0.1 to 10 at. of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained. A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.
    Type: Grant
    Filed: July 3, 2001
    Date of Patent: September 30, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
  • Publication number: 20030150990
    Abstract: To provide an atomic force microscopy which allows the measurement of the configuration of a surface being measured by using the phenomenon observed between the surface being measured and a probe approaching thereto at very fine distance.
    Type: Application
    Filed: December 4, 2002
    Publication date: August 14, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Hiroshi Tani, Yoko Ogawa, Masanori Inoue, Takaaki Shirakura, Koji Sonoda
  • Patent number: 6335103
    Abstract: A magnetic recording medium including a substrate and a magnetic layer on the substrate which is a Co-based alloy including Pt and/or Ir, including at least one of Ti, Zr, Hr, V, Nb, Ta, Cr, Mo, W, Ge, and Si, and including oxygen. A magnetic memory apparatus including the magnetic recording medium.
    Type: Grant
    Filed: May 6, 1997
    Date of Patent: January 1, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
  • Publication number: 20010053458
    Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.
    Type: Application
    Filed: July 3, 2001
    Publication date: December 20, 2001
    Applicant: Hitachi, Ltd.
    Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
  • Patent number: 6010794
    Abstract: A magnetic recording medium including a substrate and a magnetic layer on the substrate which is a Co-based alloy including Pt and/or Ir, including at least one of Ti, Zr, Hr, V, Nb, Ta, Cr, Mo, W, Ge, and Si, and including oxygen. A magnetic memory apparatus including the magnetic recording medium.
    Type: Grant
    Filed: May 6, 1997
    Date of Patent: January 4, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
  • Patent number: 5985402
    Abstract: In a thin film magnetic disk, a micro projections are formed on a substrate in a circumferential direction. A height of the micro projections is several nm to several tens of nm and a density of the micro projections is several hundred pcs/mm to several tens of thousands of pcs/mm.sup.2. With this arrangement, a magnetic disk fulfilling a head floating characteristic of a narrow space and further fulfilling a mechanical anti-sliding characteristic such as a contact start-stops characteristic and a head stickiness and the like is provided so that high reliability is attained. In the thin film magnetic disk, a bearing ratio curve of a sectional shape measured in a radial direction of the textured substrate has a bearing ratio of 0.1 to 10% at the surface layer (a cutting height of 5 to 10 nm). In this way, a pressure receiving area under a sliding of the magnetic head is increased.
    Type: Grant
    Filed: August 24, 1992
    Date of Patent: November 16, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Takao Nakamura, Takaaki Shirakura, Hiroyuki Kataoka
  • Patent number: 5825591
    Abstract: The present invention relates to a magnetic disk unit of a high memory capacity wherein a magnetic head and a magnetic disk with a lubricant layer formed on the surface thereof are allowed to perform a relative motion in a mutually contacted state to write and read out information of a high recording density, and the invention is also concerned with the shape and material of the magnetic head suitable for a continual sliding motion of the head on the magnetic disk surface, as well as the lubricant layer formed on the disk surface. According to the present invention, the magnetic head, which has a slider surface of a predetermined curvature, is supported by an arm through a spring and is pushed onto the magnetic disk surface with the lubricant layer formed thereon, then with rotation of the magnetic disk, the lubricant layer liquefies and information is recorded or read out in a contacted state of the head and the disk.
    Type: Grant
    Filed: December 18, 1996
    Date of Patent: October 20, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Takao Nakamura, Nobuya Sekiyama, Keiko Nakano, Kenji Furusawa, Hiroyuki Kataoka, Takaaki Shirakura, Shinya Matsuoka
  • Patent number: 5744256
    Abstract: The present invention relates to a high-density magnetic recording medium (or "media" as it is sometimes called) for a recording/reproduction system (such as thosed used in computer disk drives) and, more particularly, to a magnetic recording medium having a plurality of magnetic recording layers such that the uppermost layer is comparatively thinner and more densely structured than the lower magnetic recording layers. The present magnetic recording medium comprises a non-magnetic plated substrate, a non-magnetic underlying layer laminated on the plated substrate, a plurality of magnetic alloy layers including the uppermost layer laminated onto the underlying layer, a non-magnetic covering layer laminated onto the uppermost layer, and a lubricating layer formed onto the non-magnetic covering layer.
    Type: Grant
    Filed: September 16, 1992
    Date of Patent: April 28, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Noriyoshi Goda, Shinya Matsuoka, Tatsuo Kawaide, Takaaki Shirakura
  • Patent number: 5737159
    Abstract: In a thin film magnetic disk, a micro projections are formed on a substrate in a circumferential direction. A height of the micro projections is several nm to several tens of nm and a density of the micro projections is several hundred pcs/mm to several tens of thousands of pcs/mm.sup.2. With this arrangement, a magnetic disk fulfilling a head floating characteristic of a narrow space and further fulfilling a mechanical anti-sliding characteristic such as a contact start-stops characteristic and a head stickiness and the like is provided so that high reliability is attained. In the thin film magnetic disk, a bearing ratio curve of a sectional shape measured in a radial direction of the textured substrate has a bearing ratio of 0.1 to 10% at the surface layer (a cutting height of 5 to 10 nm). In this way, a pressure receiving area under a sliding of the magnetic head is increased.
    Type: Grant
    Filed: July 1, 1996
    Date of Patent: April 7, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Takao Nakamura, Takaaki Shirakura, Hiroyuki Kataoka
  • Patent number: 5665478
    Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.
    Type: Grant
    Filed: October 24, 1994
    Date of Patent: September 9, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
  • Patent number: 5158833
    Abstract: A magnetic recording medium having high recording density and being capable of obtaining excellent over-write characteristics by having a magnetic layer including Co and Ni as its principal components on a non-magnetic substrate, the Ni content of the magnetic layer is greater at portions closer to the surface of the magnetic layer in the direction of its thickness; the Ni content at portions closer to the surface of the magnetic layer is 20.about.50 at %; and the portion closer to the surface of the magnetic layer has at least one element selected from the group consisting of Zr, Ti, Pt, Ru, Ta, Rh, V, Nb, Cr and Pd.
    Type: Grant
    Filed: February 26, 1990
    Date of Patent: October 27, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Shinya Matsuoka, Masaki Ohura, Takaaki Shirakura, Yoshihiro Shiraisi
  • Patent number: 5143794
    Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W. Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.
    Type: Grant
    Filed: August 8, 1989
    Date of Patent: September 1, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
  • Patent number: 4939614
    Abstract: A magnetic disk medium in which texture working is performed on surfaces of a substrate or on surfaces of subbing films provided on the substrate to attain circumferential worked-traces so that the contact start stop area thereof is different from the recording/reproducing area thereof in roughness of the worked surfaces.
    Type: Grant
    Filed: March 31, 1988
    Date of Patent: July 3, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Takaaki Shirakura, Shinya Matsuoka, Hiroshi Yashiki, Masanori Arayashiki, Masaki Ohura
  • Patent number: 4842917
    Abstract: A magnetic recording medium having a magnetic film formed on a substrate directly or through an underlayer from an alloy containing Co as a principal component. The central line average surface roughness Ra and maximum surface roughness Rmax of the magnetic film in a direction perpendicular to the direction of magnetic recording are selected so as to fall within the ranges of 1 nm.ltoreq.Ra.ltoreq.20 nm and Rmax.ltoreq.25 Ra, respectively, and the in-plane magnetic anisotropy energy Ku of the magnetic film is selected to fall within the range of 0.ltoreq.Ku.ltoreq.8.times.10.sup.5 erg/cm.sup.3. Thus, it is possible to minimize the value of modulation which represents the degree of variation of read output on the same circumference of a magnetic disk. It is also possible to reduce the noise generated in read and write operations by forming the magnetic film so as have no crystallographic orientation.
    Type: Grant
    Filed: August 24, 1987
    Date of Patent: June 27, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Tomoyuki Ohno, Yoshihiro Shiroishi, Sadao Hishiyama, Hiroyuki Suzuki, Takaaki Shirakura, Shinya Matsuoka, Makoto Sano, Takao Nakamura, Kazumasa Takagi, Tokuumi Fukazawa, Kenzo Susa
  • Patent number: 4786553
    Abstract: A magnetic recording medium comprises a non-magnetic substrate and a thin magnetic film, the thin magnetic film being composed mainly of Co, Ni and at least one of Zr and Hf, and a concentration of Zr, Hf or Zr and Hf as contained in the thin magnetic film being 0.1 to 30% by atom on the basis of the total of Co and Ni, and has a considerably higher corrosion resistance than that of the conventional magnetic recording medium having a thin Co-Ni magnetic film.
    Type: Grant
    Filed: March 27, 1987
    Date of Patent: November 22, 1988
    Assignee: Hitachi, Ltd.
    Inventors: Yoshihiro Shiroishi, Sadao Hishiyama, Hiroyuki Suzuki, Norikazu Tsumita, Tsuneo Suganuma, Yoshio Gobara, Masaaki Hayashi, Makoto Sano, Takaaki Shirakura