Patents by Inventor Soichi Oikawa

Soichi Oikawa 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: 20070072012
    Abstract: To provide a magnetic recording medium having a magnetic recording layer consisting of fine crystal grains with improved orientation. The soft magnetic layer 3, the seed layer 4, the under layer 5 and the magnetic recording layer 7 are formed successively on the non-magnetic substrate 1, wherein the seed layer 4 is made of a material containing Ni, the under layer 5 has a grain isolation type structure in which grains made of a non-magnetic material are isolated in a non-magnetic matrix and the non-magnetic matrix is made of a material containing Y2O3. With this constitution, the under layer 5 has improved characteristics in terms of uniformity of grains, sharpness of grain boundary, fineness of the grains and crystal orientation, and therefore the magnetic recording layer 7 that is formed on the under layer also has improved characteristics in terms of uniformity of grains, sharpness of grain boundary, fineness of the grains and crystal orientation.
    Type: Application
    Filed: July 13, 2004
    Publication date: March 29, 2007
    Inventors: Futoshi Nakamura, Soichi Oikawa, Takeshi Iwasaki, Tomoyuki Maeda, Kenji Shimizu, Hiroshi Sakai
  • Publication number: 20070042227
    Abstract: To make possible high density recording by making the structure of the perpendicular magnetic recording layer finer. A perpendicular magnetic recording medium 10 includes at least a nonmagnetic under layer 2, a perpendicular magnetic layer 3, and a protective layer which are stacked on a nonmagnetic substrate 1, wherein the perpendicular magnetic layer includes ferromagnetic crystal grains and nonmagnetic crystal grain boundary regions, wherein the crystal grain boundary region includes at least two kinds of oxide.
    Type: Application
    Filed: September 22, 2004
    Publication date: February 22, 2007
    Inventors: Takeshi Iwasaki, Soichi Oikawa, Futoshi Nakamura, Tomoyuki Maeda, Hiroshi Sakai, Akira Sakawaki, Kenji Shimizu
  • Patent number: 7166376
    Abstract: A multi-layer including a magnetic recording layer and a high-magnetostriction layer having a magnetostriction constant larger than that of the magnetic recording layer is formed.
    Type: Grant
    Filed: February 26, 2004
    Date of Patent: January 23, 2007
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Takashi Hikosaka, Futoshi Nakamura, Soichi Oikawa, Takeshi Iwasaki, Tomoyuki Maeda, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
  • Publication number: 20060269794
    Abstract: In a perpendicular magnetic recording medium, a multilayered underlayer including a first metal underlayer, a second metal underlayer having no solid solution properties with respect to the first metal underlayer and having a hole, and a third metal underlayer having solid solution properties with respect to the first metal underlayer and having no solid solution properties with respect to the second metal underlayer is formed on a substrate, and a magnetic recording layer is formed on the multilayered underlayer.
    Type: Application
    Filed: May 26, 2006
    Publication date: November 30, 2006
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Soichi Oikawa
  • Patent number: 7141316
    Abstract: Disclosed is a perpendicular magnetic recording medium in which an undercoating layer having crystal grains and a grain boundary material containing a carbide or boride is formed below a perpendicular magnetic recording layer, and another undercoating layer containing one of elements forming the crystal grains is formed below the aforementioned undercoating layer, and which can perform high?density recording by further decreasing the grain size of the perpendicular magnetic recording layer.
    Type: Grant
    Filed: March 17, 2004
    Date of Patent: November 28, 2006
    Assignees: Kabushiki Kaisha Toshiba, Showa Denko K. K.
    Inventors: Takeshi Iwasaki, Takashi Hikosaka, Soichi Oikawa, Futoshi Nakamura, Tomoyuki Maeda, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
  • Patent number: 7138194
    Abstract: The magnetic recording medium comprises a soft magnetic undercoat film, an orientation control film that controls the orientation of a film provided directly above, a perpendicular magnetic film of which axis of easy magnetization is generally oriented perpendicular to a non-magnetic substrate, and a protective film, that are provided on the non-magnetic substrate, wherein the orientation control film is made of a Co alloy which contains one or more elements selected from Ti, V, Sr, Y, Nb, Mo, Hf, Ta, Ni and W.
    Type: Grant
    Filed: July 31, 2003
    Date of Patent: November 21, 2006
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Kenji Shimizu, Akira Sakawaki, Hiroshi Sakai, Takashi Hikosaka, Soichi Oikawa
  • Patent number: 7132176
    Abstract: A perpendicular magnetic recording medium includes a magnetic recording layer stacked on a substrate and having a first perpendicular magnetic recording layer containing cobalt, and a second perpendicular magnetic recording layer mainly containing a crystalline alloy which contains a rare earth element and a transition metal.
    Type: Grant
    Filed: July 25, 2003
    Date of Patent: November 7, 2006
    Assignees: Kabushiki Kaisha Toshiba, Showa Denko K.K.
    Inventors: Takeshi Iwasaki, Takashi Hikosaka, Soichi Oikawa, Futoshi Nakamura, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
  • Publication number: 20060204791
    Abstract: A magnetic recording medium which is provided on a nonmagnetic substrate 1 with at least an orientation-controlling layer 3 for controlling the orientation of a layer formed directly thereon, a perpendicularly magnetic layer 4 having an easily magnetizing axis oriented mainly perpendicularly relative to the nonmagnetic substrate 1, and a protective layer 5 and characterized in that the perpendicularly magnetic layer 4 includes two or more magnetic layers, that at least one of the magnetic layers is a layer 4a having Co as a main component and containing Pt as well and containing an oxide and that at least another of the magnetic layers is a layer 4b having Co as a main component and containing Cr as well and containing no oxide.
    Type: Application
    Filed: April 7, 2004
    Publication date: September 14, 2006
    Inventors: Akira Sakawaki, Kenji Shimizu, Kazuo Kobayashi, Hiroshi Sakai, Soichi Oikawa, Takeshi Iwasaki, Tomoyuki Maeda, Futoshi Nakamura
  • Patent number: 7105239
    Abstract: In a magnetic recording medium, a longitudinal hard magnetic layer, interlayer, longitudinal soft magnetic layer, and magnetic recording layer are multilayered on a substrate. The interlayer is one of a magnetic layer having saturation magnetization smaller than that of the longitudinal hard magnetic layer, a nonmagnetic layer mainly containing cobalt or ruthenium or having a thickness of 0.5 nm or less, and an oxide layer of the longitudinal hard magnetic layer.
    Type: Grant
    Filed: September 5, 2002
    Date of Patent: September 12, 2006
    Assignees: Kabushiki Kaisha Toshiba, Showa Denko K.K.
    Inventors: Soichi Oikawa, Takashi Hikosaka, Futoshi Nakamura, Takeshi Iwasaki, Hiroshi Sakai, Akira Sakawaki, Kenji Shimizu
  • Publication number: 20060141292
    Abstract: At least three underlayers, i.e., a first underlayer containing, as a main component, at least one element selected from Ag, Ir, Ni, Pd, Pt, Rh, Hf, Re, Ru, Ti, Ta, Zr, Mg, and Al, a second underlayer containing Mg or Al and Si, and a third underlayer containing, as a main component, at least one element selected from Pt, Pd, Ru, Rh, Co, and Ti, are formed between a substrate and magnetic recording layer.
    Type: Application
    Filed: December 21, 2005
    Publication date: June 29, 2006
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Takeshi Iwasaki, Akira Kikitsu, Soichi Oikawa, Tomoyuki Maeda
  • Patent number: 7056606
    Abstract: A magnetic recording medium comprising: on a non-magnetic substrate, at least a soft magnetic undercoat film comprising a soft magnetic material; an orientation control film for controlling an orientation of a film directly above; a perpendicular magnetic film in which an axis of easy magnetization is oriented mainly perpendicularly with respect to the substrate; and a protection film, wherein the perpendicular magnetic film has a structure in which a large number of magnetic grains are separated by a grain boundary layer, and an average separating distance between the magnetic grains along a straight line which connects centers of gravity of mutually neighboring magnetic grains is 1 nm or greater.
    Type: Grant
    Filed: February 20, 2004
    Date of Patent: June 6, 2006
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Kenji Shimizu, Akira Sakawaki, Hiroshi Sakai, Takashi Hikosaka, Soichi Oikawa
  • Patent number: 7033684
    Abstract: A magnetic recording medium comprising at least a soft magnetic layer, an orientation control film that controls the orientation of a film provided directly thereabove, an intermediate film, a perpendicular magnetic recording film of which the axis of easy magnetization is generally oriented perpendicular to a non-magnetic substrate, and a protective film, that are provided on said substrate, wherein the intermediate film has saturation magnetization Ms of at least 20 (emu/cc) and equal to or less than 200 (emu/cc), a method of manufacture thereof, and a magnetic read/write apparatus.
    Type: Grant
    Filed: July 14, 2003
    Date of Patent: April 25, 2006
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Kenji Shimizu, Akira Sakawaki, Hiroshi Sakai, Takashi Hikosaka, Soichi Oikawa
  • Publication number: 20050214590
    Abstract: A large grain diameter under-layer of at least one selected from Cu, Ni or Rh, comprising large average diameter crystalline grains of 50 nm or more than 50 nm with the (100) crystal plane of the grains oriented parallel to the substrate surface, was formed on a substrate. Then, a magnetic recording layer was deposited on the under-layer. The magnetic recording medium carrying this structure showed very small magnetic crystalline grains in magnetic layer, and excellent overwrite characteristics and signal to noise ratio at high recording density.
    Type: Application
    Filed: March 9, 2005
    Publication date: September 29, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tomoyuki Maeda, Akira Kikitsu, Soichi Oikawa, Takeshi Iwasaki
  • Publication number: 20050214591
    Abstract: A magnetic recording layer is formed on an under-layer comprising a Cu crystalline grain layer and a deposited nitrogen atom layer on the Cu crystalline grain layer surface. Then the magnetic recording layer comprising very small average grain diameter and sharp grain diameter distribution is obtained. The magnetic recording medium comprising the magnetic recording layer shows excellent signal to noise ratio at high density recording.
    Type: Application
    Filed: March 16, 2005
    Publication date: September 29, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tomoyuki Maeda, Akira Kikitsu, Soichi Oikawa, Takeshi Iwasaki
  • Publication number: 20050214588
    Abstract: Disclosed is a perpendicular magnetic recording medium including: a nonmagnetic substrate; a first underlayer formed on the nonmagnetic substrate, mainly composed of at least two kinds selected from a group consisting of Fe2O3, CO3O4, MgO, MoO3, Mn3O4, SiO2, Al2O3, TiO2, and ZrO2, and having crystal grains growing in a columnar shape and crystal grain boundaries surrounding the crystal grains; a nonmagnetic second underlayer formed on the first underlayer and having crystal grains with one of a face-centered cubic structure and a hexagonal close-packed structure growing on the crystal grains of the first underlayer; a magnetic layer formed on the second underlayer; and a protective film formed on the magnetic layer.
    Type: Application
    Filed: March 17, 2005
    Publication date: September 29, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takeshi Iwasaki, Akira Kikitsu, Soichi Oikawa, Tomoyuki Maeda
  • Publication number: 20050214592
    Abstract: A grain diameter controlling crystalline layer comprising crystalline grains of a metal selected from the group consisting essentially of Cu, Ni, Rh and Pt was formed on a substrate. Then, deposited atom layer of at least one element selected from the group consisting of oxygen and carbon was formed on the surface of the grain diameter control layer. A magnetic recording layer was deposited on the atoms deposited grain diameter controlling crystalline layer. Then a magnetic recording medium in which the magnetic crystalline grains has small grain diameter and small grain diameter distribution, and the magnetic recording medium shows increased signal to noise ratio at high recording density.
    Type: Application
    Filed: March 22, 2005
    Publication date: September 29, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tomoyuki Maeda, Akira Kikitsu, Soichi Oikawa, Takeshi Iwasaki
  • Publication number: 20050214520
    Abstract: A perpendicular magnetic recording medium suitable for attaining a low noise high magnetic recording density is obtained. The medium has a small average magnetic grain diameter, a small magnetic grain diameter distribution, a high perpendicular crystallographic magnetic grain orientation and a high regularity magnetic grain arrangement. The perpendicular magnetic recording medium comprises a soft magnetic layer, a granular under-layer and a perpendicular magnetic recording layer on a substrate. The granular under-layer is formed on a metal under-layer. The metal grains in the granular layer are separated by nonmagnetic inter-grain material and are partially penetrated into the metal under-layer. The perpendicular magnetic recording layer is formed on the granular layer. Then a perpendicular magnetic recording medium shows high signal to noise ratio and excellent high-density recording characteristics.
    Type: Application
    Filed: March 15, 2005
    Publication date: September 29, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Soichi Oikawa, Takeshi Iwasaki, Tomoyuki Maeda, Akira Kikitsu
  • Patent number: 6942936
    Abstract: A medium having at least a nonmagnetic substrate, soft magnetic backing layer, soft magnetic underlayer, and perpendicular magnetic recording layer, and An oxidized layer of the soft magnetic backing layer is also formed on the soft magnetic backing layer, and the soft magnetic underlayer has a three-layered structure including a first soft magnetic layer, interlayer, and second soft magnetic layer, a crystalline orientation control layer, e.g., an Ni orientation control layer is formed between the soft magnetic underlayer and the perpendicular magnetic recording layer.
    Type: Grant
    Filed: August 14, 2003
    Date of Patent: September 13, 2005
    Assignees: Kabushiki Kaisha Toshiba, Showa Denko K.K.
    Inventors: Soichi Oikawa, Takashi Hikosaka, Hiroshi Sakai, Akira Sakawaki, Kenji Shimizu
  • Patent number: 6902835
    Abstract: A double layered perpendicular recording media having, between a soft magnetic layer and perpendicular magnetic recording layer, an alignment control layer containing an amorphous portion, a crystal size control layer, and an underlayer having one of a hexagonal closest packed structure and a face-centered cubic structure.
    Type: Grant
    Filed: June 5, 2003
    Date of Patent: June 7, 2005
    Assignees: Kabushiki Kaisha Toshiba, Showa Denko K.K.
    Inventors: Takashi Hikosaka, Takeshi Iwasaki, Futoshi Nakamura, Soichi Oikawa, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
  • Publication number: 20050117250
    Abstract: A magnetic recording head which records information on a recording medium by a vertical magnetic recording method, the magnetic recording head comprises a magnetic pole piece which generates a recording magnetic flux perpendicular to the recording surface of a recording medium and which includes a side parallel to the track width direction of the recording medium, and a concave part which is made concavely in the side parallel to the track width direction of the recording medium so as to have a longitudinal direction parallel to the recording surface, with the length of the magnetic pole piece in the track width direction of the recording medium being equal to 0.3 micrometers or less.
    Type: Application
    Filed: September 17, 2004
    Publication date: June 2, 2005
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Soichi Oikawa