Patents by Inventor Masaaki Futamoto

Masaaki Futamoto 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: 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: 6278593
    Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semicondutor or an antiferromagnetic material against the magnetic layers, and the magneto-resistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.
    Type: Grant
    Filed: December 21, 1999
    Date of Patent: August 21, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Nakatani, Masahiro Kitada, Naoki Koyama, Isamu Yuito, Hisashi Takano, Eijin Moriwaki, Mikio Suzuki, Masaaki Futamoto, Fumio Kugiya, Yoshibumi Matsuda, Kazuo Shiiki, Yoshinori Miyamura, Kyo Akagi, Takeshi Nakao, Hirotsugu Fukuoka, Takayuki Munemoto, Tokuho Takagaki, Toshio Kobayashi, Hideo Tanabe, Noboru Shimizu
  • Publication number: 20010009730
    Abstract: Magnetic recording medium includes at least two layers having different magnetic anisotropy constants formed on a substrate and the perpendicular magnetic anisotropy of the second magnetic film of those magnetic films, far from the substrate surface, made equal to or larger than that of the first magnetic film near to the substrate surface, thus improving the magnetic isolation of the first magnetic film near to the substrate surface.
    Type: Application
    Filed: August 24, 1999
    Publication date: July 26, 2001
    Inventors: MASAAKI FUTAMOTO, NOBUYUKI INABA, YOSHIYUKI HIRAYAMA, YUKIO HONDA, KAZUETSU YOSHIDA, KENYA ITO
  • Patent number: 6251532
    Abstract: A magnetic recording medium capable of reducing noise and an error rate of the medium comprises a nonmagnetic substrate; a magnetic layer formed on the surface of the nonmagnetic substrate directly or through a nonmagnetic underlayer; and a protective layer formed on the magnetic layer. The magnetic recording medium satisfies the following relationships: −0.5≦{Hc(1)−Hc(p)}/Hc(1)≦0.3 Hc(1)≧2 kOe 20 G×&mgr;m≦Br(1)×t≦100 G×&mgr;m where Hc(1) is a corecivity of the magnetic layer measured in the longitudinal direction; Hc(p) is a coercivity of the magnetic layer measured in the perpendicular direction; Br(1) is a remanent magnetization of the magnetic layer measured in the longitudinal direction; and “t” is a layer thickness of the magnetic layer.
    Type: Grant
    Filed: November 9, 1995
    Date of Patent: June 26, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Masaaki Futamoto, Nobuyuki Inaba, Tomoo Yamamoto, Masukazu Igarashi, Yuzuru Hosoe, Akira Ishikawa
  • Patent number: 6183893
    Abstract: The present invention relates to a perpendicular magnetic recording medium and a magnetic storage apparatus which are improved to be suitable for high-density magnetic recording. An object thereof is to provide the perpendicular magnetic recording medium and the magnetic storage apparatus which have a low noise property for realizing a recording density of 10 Gb/in.2 or more and a high stability against thermal fluctuation. The perpendicular magnetic recording medium comprising a perpendicular magnetic film formed through an underlayer on a nonmagnetic substrate, wherein the underlayer comprises a material having a hexagonal close packed structure or an amorphous structure, and has a first underlayer nearer to the substrate, and a second underlayer having a hexagonal close packed structure formed on the first underlayer and a preferred growth orientation of [0001] and comprising a material capable of hetero-epitaxy growth onto the perpendicular magnetic film.
    Type: Grant
    Filed: April 5, 1999
    Date of Patent: February 6, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Masaaki Futamoto, Yoshiyuki Hirayama, Kenya Ito, Kazuetsu Yoshida, Yukio Honda, Nobuyuki Inaba
  • 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: 6011674
    Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-denisity recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.
    Type: Grant
    Filed: April 2, 1996
    Date of Patent: January 4, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Nakatani, Masahiro Kitada, Naoki Koyama, Isamu Yuito, Hisashi Takano, Eijin Moriwaki, Mikio Suzuki, Masaaki Futamoto, Fumio Kugiya, Yoshibumi Matsuda, Kazuo Shiiki, Yoshinori Miyamura, Kyo Akagi, Takeshi Nakao, Hirotsugu Fukuoka, Takayuki Munemoto, Tokuho Takagaki, Toshio Kobayashi, Hideo Tanabe, Noboru Shimizu
  • 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: 5875082
    Abstract: A magnetic recording medium wherein, when the axis of easy magnetization of the magnetic recording medium for magnetically recording information by means of a magnetic head is projected onto a surface of the magnetic recording medium, the axis projected onto the surface of the magnetic recording medium exists so as to be unidirectionally inclined with respect to the direction of a track on which information is to be recorded, whereby, by using the magnetic recording medium, there can be provided a magnetic head and a magnetic read-write apparatus greatly improved in longitudinal recording density.
    Type: Grant
    Filed: February 4, 1997
    Date of Patent: February 23, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Takanobu Takayama, Kiwamu Tanahashi, Kazuetsu Yoshida, Mikio Suzuki, Yoshiyuki Hirayama, Masaaki Futamoto, Yohji Maruyama
  • Patent number: 5851643
    Abstract: A magnetic recording media with a magnetic film made from at least two layers stacked via a non-magnetic intermediate layer, wherein the magnetic film is formed on a structure control underlayer situated on a non-magnetic substrate. A magnetic recording system is also disclosed which includes this magnetic recording media and a magnetic recording head for recording on and reading back from the magnetic recording media. The system further includes a disk drive system, which generates relative motion between the magnetic recording media and the magnetic recording head, and an actuator which determines an appropriate location, on the magnetic recording media, over which the head should be located.
    Type: Grant
    Filed: March 26, 1997
    Date of Patent: December 22, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Yukio Honda, Nobuyuki Inaba, Mikio Suzuki, Masaaki Futamoto, Hiroyuki Awano, Yoshibumi Matsuda, Yoshihiro Shiroishi
  • Patent number: 5766718
    Abstract: It is disclosed that a longitudinal magnetic recording medium and apparatus has recording sections having longitudinal magnetic films magnetically isolated in a recording direction. The magnetically isolated recording sections can record a single bit each so that the longitudinal magnetic recording medium can remove the irregular domain boundary of its own caused on boundaries of magnetization reversals in the recording direction. This can improve the signal-to-media noise ratio to a great extent in writing and reading.
    Type: Grant
    Filed: January 31, 1994
    Date of Patent: June 16, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Yoshibumi Matsuda, Masaaki Futamoto, Fumio Kugiya, Yoshinori Miyamura, Takeshi Nakano, Hisashi Takano, Kyo Akagi, Mikio Suzuki, Yasuhide Ouchi
  • Patent number: 5759681
    Abstract: A magnetic recording system includes an intermediate layer arranged between adjacent ones of a plurality of magnetic layers constituting a magnetic recording medium, the magnetic recording medium driven by a drive section in the recording direction, and a magnetic head including a write section and a read-back section set in relative motion with respect to the magnetic recording medium. Signals are applied to the magnetic head and the output signals from the magnetic head are read back by a read/write signal processing device. The read-back section of the magnetic head includes a magnetoresistive magnetic head. The magnetic layers of the magnetic recording medium include crystal grains having different crystal orientations and existing in overlapped positions in the direction perpendicular to the medium surface. High-density information read/write operation thus is made possible with an improved reliability.
    Type: Grant
    Filed: February 1, 1996
    Date of Patent: June 2, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Yuzuru Hosoe, Kazuetsu Yoshida, Nobuyuki Inaba, Tomoo Yamamoto, Akira Ishikawa, Masaaki Futamoto, Hiroyuki Kataoka, Yoshihiro Shiroishi
  • Patent number: 5738927
    Abstract: A film 12 with perpendicular magnetic anisotropy and a protective film 13 are formed over a single-crystal substrate 11. This substrate is made of either a single crystal having a hexagonal crystal structure and a plane (0001) in parallel with the substrate plane or a single crystal having a cubic crystal structure and a plane (111) in parallel with the substrate plane, and the film is epitaxially grown such that its easy axis of magnetization is perpendicular to the substrate plane. As a result, the film can have its perpendicular orientation and perpendicular magnetic anisotropy improved to effect a perpendicular magnetic recording of high density thereby to provide the perpendicular magnetic recording media, of which the film has a remarkably enhanced orientation.
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: April 14, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Nakamura, Masaaki Futamoto, Yoshiyuki Hirayama, Mikio Suzuki, Yukio Honda, Takanobu Takayama
  • Patent number: 5736235
    Abstract: A magnetic recording medium, its fabrication method, and a magnetic recording apparatus in which both saturation induction and coercive force of a magnetic film is made high as they are near a surface of the recording medium. A high density information recording can be made higher than 50 kFCI in linear recording density even for spacing around 0.2 .mu.m.
    Type: Grant
    Filed: August 6, 1991
    Date of Patent: April 7, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Yoshibumi Matsuda, Masaaki Futamoto, Yoshinori Miyamura, Tokuho Takagaki, Hisashi Takano, Fumio Kugiya, Takeshi Nakao, Kyo Akagi, Mikio Suzuki, Hirotsugu Fukuoka, Takayuki Munemoto
  • Patent number: 5726837
    Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.
    Type: Grant
    Filed: October 24, 1994
    Date of Patent: March 10, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Ryoichi Nakatani, Masahiro Kitada, Naoki Koyama, Isamu Yuito, Hisashi Takano, Eijin Moriwaki, Mikio Suzuki, Masaaki Futamoto, Fumio Kugiya, Yoshibumi Matsuda, Kazuo Shiiki, Yoshinori Miyamura, Kyo Akagi, Takeshi Nakao, Hirotsugu Fukuoka, Takayuki Munemoto, Tokuho Takagaki, Toshio Kobayashi, Hideo Tanabe, Noboru Shimizu
  • Patent number: 5685958
    Abstract: A magnetic recording medium is constructed with a substrate made of glass, one or two underlayers, and a magnetic film. In order that the easy magnetization axis of the magnetic film is parallel to the magnetic film, an underlayer having an NaCl crystallographic structure is superposed on the substrate. A magnetic film made of a Co based alloy having a hexagonal close packed crystallographic structure is formed on this underlayer, putting an underlayer made of a material having a body centered cubic crystallographic structure therebetween at need. Magnetic anisotropy of the magnetic film is increased by forming grooves in a predetermined direction in a surface portion of the substrate. These grooves play a role also for defining the orientation of the underlayer made of the material having an NaCl crystallographic structure.
    Type: Grant
    Filed: October 17, 1996
    Date of Patent: November 11, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Masaaki Futamoto, Atsushi Nakamura, Nobuyuki Inaba, Yoshiyuki Hirayama, Yoshibumi Matsuda, Mikio Suzuki, Yukio Honda
  • Patent number: 5650889
    Abstract: A magnetic recording medium having a high coercivity and a high S/N ratio for high-density operation can include either a conductive or a nonconductive substrate. If the substrate is nonconductive, a conducting precoat layer is formed over the substrate. Further, an underlayer may be provided, over which a magnetic layer is formed by a bias sputtering method. The bias sputtering method may use Kr, Xe or Rn as a sputter gas, and employs a negative bias voltage. The magnetic recording medium has a product of remanent magnetization and magnetic layer thickness of 10-150 G.multidot..mu.m and a coercivity of 1600-4000 Oe. In combination with this magnetic recording medium, a large-capacity magnetic recording system has a write head that uses a magnetic material having a saturation magnetic flux density of more than 1.
    Type: Grant
    Filed: January 30, 1995
    Date of Patent: July 22, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Tomoo Yamamoto, Yuzuru Hosoe, Emi Mangyo, Masaaki Futamoto, Nobuyuki Inaba
  • Patent number: 5599580
    Abstract: A magnetic recording medium is constructed with a substrate made of glass, one or two underlayers, and a magnetic film. In order that the easy magnetization axis of the magnetic film is parallel to the magnetic film, an underlayer having an NaCl crystallographic structure is superposed on the substrate. A magnetic film made of a Co based alloy having a hexagonal close packed crystallographic structure is formed on this underlayer, putting an underlayer made of a material having a body centered cubic crystallographic structure therebetween at need. Magnetic anisotropy of the magnetic film is increased by forming grooves in a predetermined direction in a surface portion of the substrate. These grooves play a role also for defining the orientation of the underlayer made of the material having an NaCl crystallographic structure.
    Type: Grant
    Filed: April 10, 1996
    Date of Patent: February 4, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Masaaki Futamoto, Atsushi Nakamura, Nobuyuki Inaba, Yoshiyuki Hirayama, Yoshibumi Matsuda, Mikio Suzuki, Yukio Honda