Patents by Inventor Takenori Kajiwara

Takenori Kajiwara 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: 9142241
    Abstract: A perpendicular magnetic recording medium comprises a magnetic recording layer that records a signal, an underlayer formed of Ru or Ru compound below the magnetic recording layer, a non-magnetic layer formed of a non-magnetic material below the underlayer to control crystal orientation of the underlayer, a soft magnetic layer provided below the non-magnetic layer, and a substrate on which the magnetic recording layer, the underlayer, the non-magnetic layer, and the soft magnetic layer are formed. The non-magnetic layer comprises a first non-magnetic layer formed above the soft magnetic layer and a second non-magnetic layer formed above the first non-magnetic layer. The first non-magnetic layer is formed of amorphous Ni compound while the second non-magnetic layer is formed of crystalline Ni or crystalline Ni compound.
    Type: Grant
    Filed: April 23, 2013
    Date of Patent: September 22, 2015
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Takahiro Onoue, Tokichiro Sato, Takenori Kajiwara
  • Publication number: 20150027877
    Abstract: Provided is a method of manufacturing a magnetic disk comprising a granular magnetic recording layer which causes less noise even with a recording capacity thereof of 250 G or more bits per square inch; and a method for manufacturing the same. The magnetic disk according to the present invention comprises: a granular magnetic recording layer (20) which is formed on a disk substrate 10 directly or via an intermediate layer and which has non-magnetic regions between granular columnar particles; and an auxiliary recording layer (22) which is formed on the granular magnetic recording layer 20 and which causes exchange interaction among the granular columnar particles, wherein the auxiliary recording layer (22) contains 0.1 to 3 moles of oxygen.
    Type: Application
    Filed: October 14, 2014
    Publication date: January 29, 2015
    Inventors: CHIYO SAITO, TOKICHIRO SATO, TAKENORI KAJIWARA
  • Patent number: 8877359
    Abstract: Provided are a magnetic disk comprising a granular magnetic recording layer which causes less noise even with a recording capacity thereof of 250 G or more bits per square inch; and a method for manufacturing the same. The magnetic disk according to the present invention comprises: a granular magnetic recording layer (20) which is formed on a disk substrate 10 directly or via an intermediate layer and which has non-magnetic regions between granular columnar particles; and an auxiliary recording layer (22) which is formed on the granular magnetic recording layer 20 and which causes exchange interaction among the granular columnar particles, wherein the auxiliary recording layer (22) contains 0.1 to 3 moles of oxygen.
    Type: Grant
    Filed: December 7, 2009
    Date of Patent: November 4, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Chiyo Saito, Tokichiro Sato, Takenori Kajiwara
  • Patent number: 8865327
    Abstract: A perpendicular magnetic disk that includes, on a base, a soft magnetic layer, an amorphous alloy layer, a preliminary ground layer provided on the amorphous alloy layer, a ground layer formed of Ru or a Ru-type alloy having an hcp crystal structure provided on the preliminary ground layer. A granular magnetic layer is provided on the ground layer. The amorphous alloy layer contains Ta, and the preliminary ground layer includes a first preliminary ground layer formed of Ti or a Ti alloy of microcrystals and a second preliminary ground layer formed of a Ni-type alloy of an fcc crystal structure.
    Type: Grant
    Filed: March 15, 2011
    Date of Patent: October 21, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Tokichiro Sato, Takenori Kajiwara
  • Patent number: 8828566
    Abstract: [Problem] An object is to make a film thinner while keeping the function as an auxiliary recording layer and increase an SNR. [Solution] A structure of the perpendicular magnetic disk 100 according to the present invention includes, on a base 110, a granular magnetic layer 160 and an auxiliary recording layer 180 disposed above the granular magnetic layer, the granular magnetic layer having a granular structure in which a non-magnetic substance having an oxide as a main component is segregated around magnetic particles having a CoCrPt alloy as a main ingredient growing in a columnar shape to form a grain boundary part, and the auxiliary recording layer having a CoCrPtRu alloy as a main component and further containing, as a accessory component, a metal forming passivity and not being an antiferromagnet.
    Type: Grant
    Filed: May 20, 2011
    Date of Patent: September 9, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Tokichiro Sato, Takenori Kajiwara
  • Publication number: 20130230647
    Abstract: A perpendicular magnetic recording medium comprises a magnetic recording layer that records a signal, an underlayer formed of Ru or Ru compound below the magnetic recording layer, a non-magnetic layer formed of a non-magnetic material below the underlayer to control crystal orientation of the underlayer, a soft magnetic layer provided below the non-magnetic layer, and a substrate on which the magnetic recording layer, the underlayer, the non-magnetic layer, and the soft magnetic layer are formed. The non-magnetic layer comprises a first non-magnetic layer formed above the soft magnetic layer and a second non-magnetic layer formed above the first non-magnetic layer. The first non-magnetic layer is formed of amorphous Ni compound while the second non-magnetic layer is formed of crystalline Ni or crystalline Ni compound.
    Type: Application
    Filed: April 23, 2013
    Publication date: September 5, 2013
    Applicant: WD Media (Singapore) PTE.LTD.
    Inventors: Takahiro ONOUE, Tokichiro Sato, Takenori Kajiwara
  • Patent number: 8453315
    Abstract: A method for manufacturing a perpendicular magnetic disk 100 that includes a step of forming, on a base 110, a granular magnetic layer 160 in which a grain boundary portion is formed by segregation of a non-magnetic substance containing an oxide as a main component around magnetic particles containing a CoCrPt alloy grown in a columnar shape as a main component. The method also includes a step of forming an auxiliary recording layer 180 that contains a CoCrPtRu alloy as a main component and has a film thickness of 1.5 to 4 nm above the granular magnetic layer, and a step of heating the base formed with the auxiliary recording layer in a temperature range of 210 to 250° C.
    Type: Grant
    Filed: March 24, 2011
    Date of Patent: June 4, 2013
    Assignee: WD Media (Singapore) Pte, Ltd.
    Inventors: Takenori Kajiwara, Tokichiro Sato
  • Patent number: 8431258
    Abstract: A perpendicular magnetic recording medium comprises a magnetic recording layer that records a signal, an underlayer formed of Ru or Ru compound below the magnetic recording layer, a non-magnetic layer formed of a non-magnetic material below the underlayer to control crystal orientation of the underlayer, a soft magnetic layer provided below the non-magnetic layer, and a substrate on which the magnetic recording layer, the underlayer, the non-magnetic layer, and the soft magnetic layer are formed. The non-magnetic layer comprises a first non-magnetic layer formed above the soft magnetic layer and a second non-magnetic layer formed above the first non-magnetic layer. The first non-magnetic layer is formed of amorphous Ni compound while the second non-magnetic layer is formed of crystalline Ni or crystalline Ni compound.
    Type: Grant
    Filed: March 30, 2010
    Date of Patent: April 30, 2013
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Takahiro Onoue, Tokichiro Sato, Takenori Kajiwara
  • Patent number: 8404370
    Abstract: A perpendicular magnetic recording medium 100 has, over a substrate, at least a magnetic recording layer 122 with a granular structure in which nonmagnetic grain boundaries are formed between magnetic grains continuously grown into a columnar shape. The magnetic grains of the magnetic recording layer 122 contain Co, Cr, and Pt. The magnetic recording layer 122 contains at least one oxide selected from a group A including SiO2, TiO2, and Cr2O3, at least one oxide selected from a group B consisting of oxides each having a larger Gibbs free energy ?G than the group A, and a reducing agent adapted to reduce the oxides of the group B.
    Type: Grant
    Filed: March 31, 2010
    Date of Patent: March 26, 2013
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Tokichiro Sato, Takahiro Onoue, Takenori Kajiwara
  • Publication number: 20120207919
    Abstract: A method of manufacturing a perpendicular magnetic disk comprises forming, on a base, a film of a first ground layer made of Ru or a Ru alloy at a first pressure, forming, on the first ground layer, a film of a second ground layer made of Ru or a Ru alloy at a second pressure higher than a first pressure, forming, on the second ground layer, a film of a third ground layer having Ru or a Ru alloy as a main component and an oxide as an accessory component at a third pressure higher than the first pressure and lower than the second pressure, and forming, on a layer above the third ground layer, a film of a granular magnetic layer in which a non-magnetic substance having an oxide is segregated around magnetic particles having an CoCrPt alloy grown in a columnar shape to form a grain boundary.
    Type: Application
    Filed: May 31, 2011
    Publication date: August 16, 2012
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: KAZUAKI SAKAMOTO, TAKENORI KAJIWARA
  • Publication number: 20120189872
    Abstract: A perpendicular magnetic disk is provided. The disk includes, on a base and in the order from bottom, a first granular magnetic layer group including a plurality of magnetic layers each having a granular structure, a non-magnetic layer having Ru or a Ru alloy as a main component, a second granular magnetic layer group including a plurality of magnetic layers each having the granular structure, and an auxiliary recording layer having a CoCrPtRu alloy as a main component. Layers closer to a front surface among the plurality of magnetic layers included in the first granular magnetic layer group having an equal or smaller content of Pt. Layers closer to the front surface among the plurality of magnetic layers included in the second granular magnetic layer group having an equal or smaller content of Pt and having an equal or larger content of an oxide.
    Type: Application
    Filed: May 20, 2011
    Publication date: July 26, 2012
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: Teiichiro Umezawa, Takenori Kajiwara, Tokichiro Sato
  • Publication number: 20120129009
    Abstract: [Summary] [Problem] An object is to make a film thinner while keeping the function as an auxiliary recording layer and increase an SNR. [Solution] A structure of the perpendicular magnetic disk 100 according to the present invention includes, on a base 110, a granular magnetic layer 160 and an auxiliary recording layer 180 disposed above the granular magnetic layer, the granular magnetic layer having a granular structure in which a non-magnetic substance having an oxide as a main component is segregated around magnetic particles having a CoCrPt alloy as a main ingredient growing in a columnar shape to form a grain boundary part, and the auxiliary recording layer having a CoCrPtRu alloy as a main component and further containing, as a accessory component, a metal forming passivity and not being an antiferromagnet.
    Type: Application
    Filed: May 20, 2011
    Publication date: May 24, 2012
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: Tokichiro Sato, Takenori Kajiwara
  • Publication number: 20120066896
    Abstract: An object of the invention is to achieve thinning while maintaining a function required for an auxiliary recording layer, thereby achieving improvement of SNR. A configuration of a method for manufacturing a perpendicular magnetic disk 100 according to the invention includes a granular magnetic layer forming step, on a base 110, a granular magnetic layer 160 in which a grain boundary portion is formed by segregation of a non-magnetic substance containing an oxide as a main component around magnetic particles containing a CoCrPt alloy grown in a columnar shape as a main component; an auxiliary recording layer forming step of forming an auxiliary recording layer 180 that contains a CoCrPtRu alloy as a main component and has a film thickness of 1.5 to 4 nm above the granular magnetic layer; and a heating step of heating the base formed with the auxiliary recording layer in a temperature range of 210 to 250° C.
    Type: Application
    Filed: March 24, 2011
    Publication date: March 22, 2012
    Applicant: WD Media (Singapore) Pte. Ltd.
    Inventors: Takenori Kajiwara, Tokichiro Sato
  • Publication number: 20120070692
    Abstract: [Problem] To make a film thinner while keeping a function as an auxiliary recording layer, and improve an SNR and an overwrite characteristic. [Solution] A typical structure of a perpendicular magnetic disk according to the present invention includes, on a base, a granular magnetic layer 160 and an auxiliary recording layer 180 disposed on the granular magnetic layer 160. The granular magnetic layer 160 has a granular structure in which a grain boundary part is formed with segregation of a non-magnetic substance having an oxide as a main component around magnetic particles having a CoCrPt alloy a main component growing in a columnar shape. The auxiliary recording layer 180 has a CoCrPtRu alloy as a main component, and has a film thickness of 1.5 nm to 4.0 nm.
    Type: Application
    Filed: March 15, 2011
    Publication date: March 22, 2012
    Applicant: WD Media (Singapore) Pte. Ltd.
    Inventors: Tokichiro Sato, Takenori Kajiwara
  • Publication number: 20110311841
    Abstract: Provided are a magnetic disk comprising a granular magnetic recording layer which causes less noise even with a recording capacity thereof of 250 G or more bits per square inch; and a method for manufacturing the same. The magnetic disk according to the present invention comprises: a granular magnetic recording layer (20) which is formed on a disk substrate 10 directly or via an intermediate layer and which has non-magnetic regions between granular columnar particles; and an auxiliary recording layer (22) which is formed on the granular magnetic recording layer 20 and which causes exchange interaction among the granular columnar particles, wherein the auxiliary recording layer (22) contains 0.1 to 3 moles of oxygen.
    Type: Application
    Filed: December 7, 2009
    Publication date: December 22, 2011
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: Chiyo Saito, Tokichiro Sato, Takenori Kajiwara
  • Publication number: 20100255348
    Abstract: A perpendicular magnetic recording medium 100 has, over a substrate, at least a magnetic recording layer 122 with a granular structure in which nonmagnetic grain boundaries are formed between magnetic grains continuously grown into a columnar shape. The magnetic grains of the magnetic recording layer 122 contain Co, Cr, and Pt. The magnetic recording layer 122 contains at least one oxide selected from a group A including SiO2, TiO2, and Cr2O3, at least one oxide selected from a group B consisting of oxides each having a larger Gibbs free energy ?G than the group A, and a reducing agent adapted to reduce the oxides of the group B.
    Type: Application
    Filed: March 31, 2010
    Publication date: October 7, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventors: Tokichiro SATO, Takahiro ONOUE, Takenori KAJIWARA
  • Publication number: 20100247964
    Abstract: A perpendicular magnetic recording medium comprises a magnetic recording layer that records a signal, an underlayer formed of Ru or Ru compound below the magnetic recording layer, a non-magnetic layer formed of a non-magnetic material below the underlayer to control crystal orientation of the underlayer, a soft magnetic layer provided below the non-magnetic layer, and a substrate on which the magnetic recording layer, the underlayer, the non-magnetic layer, and the soft magnetic layer are formed. The non-magnetic layer comprises a first non-magnetic layer formed above the soft magnetic layer and a second non-magnetic layer formed above the first non-magnetic layer. The first non-magnetic layer is formed of amorphous Ni compound while the second non-magnetic layer is formed of crystalline Ni or crystalline Ni compound.
    Type: Application
    Filed: March 30, 2010
    Publication date: September 30, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventors: Takahiro ONOUE, Tokichiro Sato, Takenori Kajiwara