Patents by Inventor Yoshibumi Matsuda

Yoshibumi Matsuda 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: 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: 20010008716
    Abstract: A magnetic recording medium having first undercoating layers 40, 40′ formed directly or via substrate face undercoating layers on a substrate 40, second undercoating layers 42, 42′ directly formed on the first undercoating layers 40, 40′, magnetic films 43, 43′ formed on the second undercoating layers 42, 42′, and protective films 44, 44′ formed on the magnetic films 43, 43′. Clusters having a large amount of oxygen are dispersed on the boundary face of the first and second undercoating layers. Preferably, the first undercoating layer is made of an alloy which includes two kinds of elements in which the difference between oxide formation standard free energies &Dgr;G° of the elements at the temperature of 250° C. is large.
    Type: Application
    Filed: February 16, 2001
    Publication date: July 19, 2001
    Inventors: Yoshibumi Matsuda, Akira Ishikawa, Yotsuo Yahisa, Yuzuru Hosoe, Tetsuya Kanbe, Koji Sakamoto
  • Patent number: 6197367
    Abstract: A magnetic recording medium having first undercoating layers 40, 40′ formed directly or via substrate face undercoating layers on a substrate 40, second undercoating layers 42, 42′ directly formed on the first undercoating layers 40, 40′, magnetic films 43, 43′ formed on the second undercoating layers 42, 42′, and protective films 44, 44′ formed on the magnetic films 43, 43′. Clusters having a large amount of oxygen are dispersed on the boundary face of the first and second undercoating layers. Preferably, the first undercoating layer is made of an alloy which includes two kinds of elements in which the difference between oxide formation standard free energies &Dgr;G° of the elements at the temperature of 250° C. is large.
    Type: Grant
    Filed: October 29, 1997
    Date of Patent: March 6, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Yoshibumi Matsuda, Akira Ishikawa, Yotsuo Yahisa, Yuzuru Hosoe, Tetsuya Kanbe, Koji Sakamoto
  • Patent number: 6069762
    Abstract: In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.
    Type: Grant
    Filed: July 9, 1999
    Date of Patent: May 30, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Hajime Aoi, Toshiaki Tsuyoshi, Makoto Koizumi, Nobumasa Nishiyama, Yoshibumi Matsuda, Takuji Ogawa, Kazuhisa Shiraishi
  • Patent number: 6014275
    Abstract: In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.
    Type: Grant
    Filed: August 22, 1996
    Date of Patent: January 11, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Hajime Aoi, Toshiaki Tsuyoshi, Makoto Koizumi, Nobumasa Nishiyama, Yoshibumi Matsuda, Takuji Ogawa, Kazuhisa Shiraishi
  • 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: 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: 5906884
    Abstract: A magnetic recording medium has a substrate made of a nonmetal nonmagnetic material whose coefficient of linear expansion lies within a range from 0.000013/deg to 0.0001/deg. A magnetic layer is formed on the substrate as a thin polycrystalline film or a thin amorphous film. The magnetic layer has Co as a main component, which exhibits a negative magnetostrictive constant so that its coercive force rises in the direction of compressive strain. The magnetic layer is subjected to an in-plane compressive strain from the substrate due to a difference between the coefficient of thermal expansion of the substrate and the magnetic layer so that high coercivity is obtained in the magnetic layer.
    Type: Grant
    Filed: August 15, 1995
    Date of Patent: May 25, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Yotsuo Yahisa, Yoshibumi Matsuda, Joe Inagaki, Enji Fujita, Takao Yonekawa, Mitsuhiro Shoda, Akira Kato, Yuzuru Hosoe, Masukazu Igarashi
  • 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: 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: 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: 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
  • Patent number: 5572379
    Abstract: In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.
    Type: Grant
    Filed: September 13, 1994
    Date of Patent: November 5, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Hajime Aoi, Toshiaki Tsuyoshi, Makoto Koizumi, Nobumasa Nishiyama, Yoshibumi Matsuda, Takuji Ogawa, Kazuhisa Shiraishi
  • Patent number: 5568331
    Abstract: A method and device of head positioning in an information recording/reading device in which a magnetic recording medium with data tracks for recording information thereon is provided and a magnetic head is positioned on the data track to record/read out the information, wherein a data signal is recorded in the data recording layer of said recording medium, a servo signal is recorded in the servo signal recording layer located below said data signal recording layer, said data signal is read out using a data magnetic head whereas said servo signal is read out using a servo magnetic head, and the frequency of said servo signal is within the range of the gap-null frequency of said data magnetic head whereas the frequency of said data signal is within the range of the gap-null frequency of said servo magnetic head, and said magnetic head is positioned on the data track on the basis of said servo signal.
    Type: Grant
    Filed: October 25, 1990
    Date of Patent: October 22, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Kyo Akagi, Masaaki Futamoto, Fumio Kugiya, Yoshinori Miyamura, Hisashi Takano, Yoshibumi Matsuda, Mikio Suzuki, Takeshi Nakao, Takayuki Munemoto, Hirotsugu Fukuoka, Makoto Aihara, Tokuho Takagaki, Hajime Aoi, Yosuke Seo
  • Patent number: 5536585
    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: March 9, 1994
    Date of Patent: July 16, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Masaaki Futamoto, Atsushi Nakamura, Nobuyuki Inaba, Yoshiyuki Hirayama, Yoshibumi Matsuda, Mikio Suzuki, Yukio Honda
  • Patent number: 5390061
    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 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: June 5, 1991
    Date of Patent: February 14, 1995
    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: 5372843
    Abstract: A magnetic recording medium comprising a substrate, a diffusion element layer formed on the substrate from a material to be diffused into a magnetic film by heating, a diffusion barrier formed in a desired pattern on the diffusion barrier, and the magnetic film formed on the pattern of the diffusion barrier and on other area than the area of the pattern, the magnetic film having a portion of reduced saturation magnetization in repetition in a direction perpendicular to a recording direction. The magnetic recording medium can be obtained by forming a diffusion element layer, a diffusion barrier in a desired pattern, and a magnetic film, in a stacked form on a substrate, followed by heating.
    Type: Grant
    Filed: March 10, 1992
    Date of Patent: December 13, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Yoshinori Miyamura, Masaaki Futamoto, Yoshibumi Matsuda