Patents by Inventor Yoshihiro Tawara

Yoshihiro Tawara 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: 10403321
    Abstract: A method for manufacturing a glass substrate according to which surface roughnesses of main surfaces of a glass substrate can be reduced more than with currently available methods is provided. After the main surfaces of the glass substrate used in a magnetic disk are mirror-polished (final finishing-polished) using a polishing liquid containing organic-based particles made of, for example, a styrene-based resin, an acrylic resin, or a urethane-based resin as polishing abrasive particles, by cleaning the glass substrate using an organic-based cleaning agent, surface roughnesses of the main surfaces of the substrate can be reduced more than with currently available methods.
    Type: Grant
    Filed: September 29, 2014
    Date of Patent: September 3, 2019
    Assignee: HOYA CORPORATION
    Inventor: Yoshihiro Tawara
  • Patent number: 10068602
    Abstract: The present invention provides a method for manufacturing a glass substrate for a magnetic disk or the like according to which surface roughnesses of main surfaces of a glass substrate can be reduced more than with currently available methods. In the present invention, by mirror-polishing (final finishing-polishing) the main surfaces of the glass substrate used in a magnetic disk, for example, using a polishing liquid containing organic-based particles made of a styrene-based resin, an acrylic resin, or a urethane-based resin, as polishing abrasive particles, surface roughnesses of the main surfaces of the substrate can be reduced more than with currently available methods.
    Type: Grant
    Filed: June 29, 2014
    Date of Patent: September 4, 2018
    Assignee: HOYA CORPORATION
    Inventor: Yoshihiro Tawara
  • Publication number: 20160217818
    Abstract: A method for manufacturing a glass substrate according to which surface roughnesses of main surfaces of a glass substrate can be reduced more than with currently available methods is provided. After the main surfaces of the glass substrate used in a magnetic disk are mirror-polished (final finishing-polished) using a polishing liquid containing organic-based particles made of, for example, a styrene-based resin an acrylic resin, or a urethane-based resin as polishing abrasive particles, by cleaning the glass substrate using an organic-based cleaning agent, surface roughnesses of the main surfaces of the substrate can be reduced more than with currently available methods.
    Type: Application
    Filed: September 29, 2014
    Publication date: July 28, 2016
    Applicant: HOYA CORPORATION
    Inventor: Yoshihiro TAWARA
  • Publication number: 20160118073
    Abstract: The present invention provides a method for manufacturing a glass substrate for a magnetic disk or the like according to which surface roughnesses of main surfaces of a glass substrate can be reduced more than with currently available methods. In the present invention, by mirror-polishing (final finishing-polishing) the main surfaces of the glass substrate used in a magnetic disk, for example, using a polishing liquid containing organic-based particles made of a styrene-based resin, an acrylic resin, or a urethane-based resin, as polishing abrasive particles, surface roughnesses of the main surfaces of the substrate can be reduced more than with currently available methods.
    Type: Application
    Filed: June 29, 2014
    Publication date: April 28, 2016
    Applicant: HOYA CORPORATION
    Inventor: Yoshihiro TAWARA
  • Patent number: 9299382
    Abstract: A method of manufacturing a glass substrate for a magnetic disk includes a polishing step of polishing a main surface of a glass substrate by sandwiching the glass substrate between a pair of surface plates each having a polishing pad on its surface and by supplying a polishing liquid containing polishing abrasive particles between the glass substrate and the polishing pads. In the polishing step, the polishing liquid and each polishing pad are adjusted so that the friction coefficient falls in a range of 0.02 to 0.05.
    Type: Grant
    Filed: January 26, 2012
    Date of Patent: March 29, 2016
    Assignee: HOYA CORPORATION
    Inventors: Hideo Sakai, Yoshihiro Tawara
  • Patent number: 9186771
    Abstract: In a magnetic disk glass substrate manufacturing method, a main surface of a glass substrate is polished using a polishing liquid containing colloidal silica abrasive particles as polishing abrasive particles and a surface plate with a polishing pad, then the glass substrate is brought into contact with a liquid containing a coagulant so that the colloidal silica abrasive particles are coagulated, and then the colloidal silica abrasive particles coagulated are removed.
    Type: Grant
    Filed: March 30, 2012
    Date of Patent: November 17, 2015
    Assignee: HOYA CORPORATION
    Inventors: Hideo Sakai, Yosuke Suzuki, Yoshihiro Tawara
  • Patent number: 9183868
    Abstract: A method of manufacturing a glass substrate for a magnetic disk includes a polishing step of polishing a main surface of a glass substrate by sandwiching the glass substrate between a pair of surface plates each having a polishing pad on its surface and by supplying a polishing liquid containing polishing abrasive particles between the glass substrate and the polishing pads. In the polishing step, the polishing liquid and each polishing pad are adjusted so that the friction coefficient falls in a range of 0.02 to 0.05.
    Type: Grant
    Filed: January 26, 2012
    Date of Patent: November 10, 2015
    Assignee: HOYA CORPORATION
    Inventors: Hideo Sakai, Yoshihiro Tawara
  • Publication number: 20150158139
    Abstract: A manufacturing method of a glass substrate for a magnetic disk is provided whereby nano pits and/or nano scratches cannot be easily produced in polishing a principal face of a glass substrate using a slurry containing zirconium oxide as an abrasive. The manufacturing method of a glass substrate for a magnetic disk includes, for instance, a polishing step of polishing a principal face of a glass substrate using a slurry containing, as an abrasive, zirconium oxide abrasive grains having monoclinic crystalline structures (M) and tetragonal crystalline structures (T).
    Type: Application
    Filed: February 10, 2015
    Publication date: June 11, 2015
    Inventors: Masanori TAMAKI, Hiroki NAKAGAWA, Yoshihiro TAWARA
  • Patent number: 8974561
    Abstract: A manufacturing method of a glass substrate for a magnetic disk is provided whereby nano pits and/or nano scratches cannot be easily produced in polishing a principal face of a glass substrate using a slurry containing zirconium oxide as an abrasive. The manufacturing method of a glass substrate for a magnetic disk includes, for instance, a polishing step of polishing a principal face of a glass substrate using a slurry containing, as an abrasive, zirconium oxide abrasive grains having monoclinic crystalline structures (M) and tetragonal crystalline structures (T).
    Type: Grant
    Filed: September 26, 2012
    Date of Patent: March 10, 2015
    Assignee: Hoya Corporation
    Inventors: Masanori Tamaki, Hiroki Nakagawa, Yoshihiro Tawara
  • Publication number: 20130260027
    Abstract: Provided are: a method for manufacturing a glass substrate for a magnetic disk by using an alternative abrasive having the same polishing performance as cerium oxide, which has conventionally been used as an abrasive for polishing principal faces of glass substrates for magnetic disks; and a method for manufacturing a magnetic disk. At the time of polishing a principal face of a magnetic disk glass substrate by using a slurry, the disclosure employs a slurry containing: an abrasive made of granular zirconia; a first additive including a phosphate and/or a sulfonate; and a second additive including a re-aggregation inhibitor.
    Type: Application
    Filed: December 29, 2011
    Publication date: October 3, 2013
    Applicant: HOYA CORPORATION
    Inventors: Kyosuke IIIzumi, Yoshihiro Tawara, Kotaro Yoshimaru
  • Publication number: 20130126334
    Abstract: The present invention provides a method for manufacturing a glass substrate for a magnetic disk that enables grinding processing with fixed abrasive grains without a decrease of the grinding rate and that can manufacture a high quality glass substrate at low cost. The present invention is a method for manufacturing a glass substrate for a magnetic disk, including a grinding step of grinding a main surface of a glass substrate using a lubricant and a surface plate that has a grinding surface provided with fixed abrasive grains containing diamond particles. In the grinding step, for example, by adding Al2O3, Al3+ is allowed to be contained in the lubricant that is supplied to the surface on which grinding processing is performed of the glass substrate. The lubricant has an Al3+ content preferably in a range of 0.05 g/L to 1.0 g/L.
    Type: Application
    Filed: August 31, 2011
    Publication date: May 23, 2013
    Inventors: Yoshihiro Tawara, Kiyoshi Hayakawa, Taiji Osada
  • Publication number: 20120251711
    Abstract: In a magnetic disk glass substrate manufacturing method, a main surface of a glass substrate is polished using a polishing liquid containing colloidal silica abrasive particles as polishing abrasive particles and a surface plate with a polishing pad, then the glass substrate is brought into contact with a liquid containing a coagulant so that the colloidal silica abrasive particles are coagulated, and then the colloidal silica abrasive particles coagulated are removed.
    Type: Application
    Filed: March 30, 2012
    Publication date: October 4, 2012
    Applicant: HOYA CORPORATION
    Inventors: Hideo SAKAI, Yosuke SUZUKI, Yoshihiro TAWARA
  • Publication number: 20120196033
    Abstract: A method of manufacturing a glass substrate for a magnetic disk includes a polishing step of polishing a main surface of a glass substrate by sandwiching the glass substrate between a pair of surface plates each having a polishing pad on its surface and by supplying a polishing liquid containing polishing abrasive particles between the glass substrate and the polishing pads. In the polishing step, the polishing liquid and each polishing pad are adjusted so that the friction coefficient falls in a range of 0.02 to 0.05.
    Type: Application
    Filed: January 26, 2012
    Publication date: August 2, 2012
    Applicant: HOYA CORPORATION
    Inventors: Hideo SAKAI, Yoshihiro TAWARA
  • Publication number: 20040238002
    Abstract: In a method of producing a glass substrate for a magnetic disk, a principal surface of a glass substrate is subjected to polishing in order to impart a texture thereon. Thereafter, a treating liquid is supplied onto the principal surface of the glass substrate. While a tape is pressed against the principal surface of the glass substrate, the principal surface is cleaned.
    Type: Application
    Filed: March 2, 2004
    Publication date: December 2, 2004
    Applicant: HOYA CORPORATION
    Inventors: Hirotaka Tanaka, Yoshihiro Tawara
  • Publication number: 20030226378
    Abstract: Slurries to be supplied to the surface of a rotating glass substrate for texturing the surface to create streaks contain aggregates having diameters not larger than 0.51 &mgr;m of polycrystalline diamond particles that are dispersed in water or a water-based aqueous solution that is free of any substance having an etching effect on a glass material. A glass substrate is textured by supplying such a slurry material on its surface as the substrate is rotated and a polishing tape is pressed and run against the substrate surface.
    Type: Application
    Filed: February 11, 2003
    Publication date: December 11, 2003
    Applicant: Nihon Microcoating Co., Ltd.
    Inventors: Hiromitsu Okuyama, Tatsuya Tanifuji, Yoshihiro Tawara
  • Patent number: 6491572
    Abstract: A glass substrate for a magnetic disk has one or both of its surfaces processed by applying a suspension of a specified kind onto the surface to be processed while the substrate is rotated and a polishing tape is pressed and run against the surface to be processed. The suspension includes abrasive particles with average diameter selected according to the purpose of the processing and an aqueous solution containing a reacting liquid capable of causing a solid phase reaction at contact boundary surfaces between the surface of the glass substrate and these abrasive particles. The polishing tape is removed from the glass substrate when the polishing is over but while the tape is still running and the glass substrate is rotating. The supplying of the suspension is thereafter stopped and a washing liquid such as water is applied to the polished surface or surfaces while the substrate is still rotating. Both surfaces of a glass substrate may be polished at the same time.
    Type: Grant
    Filed: October 10, 2000
    Date of Patent: December 10, 2002
    Assignee: Nihon Microcoating Co., Ltd.
    Inventors: Yuji Horie, Takabumi Marukawa, Yoshihiro Tawara, Kanichi Endo