Patents by Inventor Teiichiro Umezawa
Teiichiro Umezawa 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).
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Publication number: 20090191331Abstract: [Object] To provide a manufacturing method that can easily enhance a reversed domain nucleation magnetic field of a magnetic recording layer in a perpendicular magnetic recording medium having, over a substrate, a soft magnetic layer, the magnetic recording layer having a granular structure, and a continuous layer having a high perpendicular magnetic anisotropy.Type: ApplicationFiled: March 31, 2007Publication date: July 30, 2009Applicants: Hoya Corporation, Hoya Magnetics Singapore PTE. LTD.Inventors: Teiichiro Umezawa, Takahiro Onoue, Chikara Takasu, Kong Kim
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Publication number: 20090117408Abstract: To provide a perpendicular magnetic recording disk having a film structure that improves overwrite characteristics (O/W) while maintaining a coercive force (Hc) high enough not to affect heat fluctuation resistance, and a manufacturing method thereof. A magnetic disk for use in perpendicular magnetic recording, having at least an underlayer, a first magnetic recording layer, and a second magnetic recording layer on a substrate in the order named, characterized in that the first magnetic recording layer and the second magnetic recording layer are each a ferromagnetic layer of a granular structure containing a nonmagnetic substance forming grain boundary portions between crystal grains containing at least Co (cobalt) and, given that the content of the nonmagnetic substance in the first magnetic recording layer is A mol % and the content of the nonmagnetic substance in the second magnetic recording layer is B mol %, A<B.Type: ApplicationFiled: March 31, 2007Publication date: May 7, 2009Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.Inventors: Teiichiro Umezawa, Lianjun Wu, Yoshiaki Sonobe, Chikara Takasu, Takahiro Onoue
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Publication number: 20090081483Abstract: A magnetic disk 10 for use in perpendicular magnetic recording, which includes an underlayer 18, a size-reduction promoting layer 20 (nonmagnetic granular layer) of a granular structure, and a magnetic recording layer 22 having a ferromagnetic layer 32 of a granular structure. The size-reduction promoting layer 20 has an inorganic oxide matrix and nonmagnetic metal crystal grains and is disposed between the underlayer 18 and the ferromagnetic layer 32, thereby reducing the size of magnetic crystal grains in the ferromagnetic layer 32.Type: ApplicationFiled: March 20, 2006Publication date: March 26, 2009Applicant: HOYA CORPORATIONInventors: Yoshiaki Sonobe, Teiichiro Umezawa, Kong Kim, Masaki Uemura
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Patent number: 7420886Abstract: There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read/write element, and a write track width is twice or more as large as a read track width in the head.Type: GrantFiled: April 20, 2007Date of Patent: September 2, 2008Assignee: Hoya CorporationInventors: Hiroshi Tomiyasu, Teiichiro Umezawa, Genshichi Hata, Takashi Morikawa, Masato Kobayashi, Masashi Suzuki, Satoshi Yokota, Tsuyoshi Watanabe
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Publication number: 20080090104Abstract: A magnetic recording medium for perpendicular magnetic recording includes a substrate, a granular layer having magnetic crystal grains exhibiting perpendicular magnetic anisotropy and nonmagnetic substances for magnetically separating the magnetic crystal grains from each other at grain boundaries of the magnetic crystal grains, and a continuous film layer having magnetic grains to be exchange-coupled to the magnetic crystal grains, the grain boundary width of the magnetic grains being smaller than that of the magnetic crystal grains, wherein separation regions for magnetically separating tracks from each other are disposed in regions between the tracks of the magnetic recording medium in at least the continuous film layer.Type: ApplicationFiled: September 27, 2007Publication date: April 17, 2008Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD., HOYA CORPORATION USAInventors: Yoshiaki SONOBE, Teiichiro UMEZAWA, Koichi WAGO
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Publication number: 20080075845Abstract: A method for manufacturing a magnetic recording medium includes the steps of (a) forming a perpendicular magnetic recording layer and (b) applying an ion beam to regions between tracks of the perpendicular magnetic recording layer so as to form separation regions for magnetically separating the tracks from each other. In the step (a), a continuous film layer composed of a multilayer film is formed, and CoB layers and Pd layers are laminated in the multilayer film. In the step (b), the CoB layers and the Pd layers are melted by the ion beam so as to form an alloy of metals contained in the CoB layers and the Pd layers to thereby form the separation regions.Type: ApplicationFiled: September 27, 2007Publication date: March 27, 2008Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD., HOYA CORPORATION USAInventors: Yoshiaki SONOBE, Teiichiro UMEZAWA, Koichi WAGO
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Publication number: 20070248844Abstract: There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read/write element, and a write track width is twice or more as large as a read track width in the head.Type: ApplicationFiled: April 20, 2007Publication date: October 25, 2007Inventors: Hiroshi Tomiyasu, Teiichiro Umezawa, Genshichi Hata, Takashi Morikawa, Masato Kobayashi, Masashi Suzuki, Satoshi Yokota, Tsuyoshi Watanabe
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Publication number: 20070148499Abstract: A magnetic disk 10 for use in perpendicular magnetic recording has at least a magnetic recording layer on a substrate 1. The magnetic recording layer is composed of a ferromagnetic layer 5 of a granular structure containing silicon (Si) or an oxide of silicon (Si) between crystal grains containing cobalt (Co), a stacked layer 7 having a first layer containing cobalt (Co) or a Co alloy and a second layer containing palladium (Pd) or platinum (Pt), and a spacer layer 6 interposed between the ferromagnetic layer 5 and the stacked layer 7. After forming the ferromagnetic layer 5 on the substrate 1 by sputtering in an argon gas atmosphere, the stacked layer 7 is formed by sputtering in the argon gas atmosphere at a gas pressure lower than that used when forming the ferromagnetic layer 5.Type: ApplicationFiled: June 29, 2005Publication date: June 28, 2007Inventors: Yoshiaki Sonobe, Teiichiro Umezawa, Chikara Takasu
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Patent number: 7220500Abstract: There is disclosed a magnetic recording medium in which a seed layer, under layer, intermediate layer, first magnetic layer, nonmagnetic layer, second magnetic layer, protective layer, and lubricant layer are successively laminated on a glass substrate, the nonmagnetic layer is constituted of an alloy containing Cr and C, and the magnetic layer is constituted of an alloy containing Co and Pt. The under layer includes at least the seed layer for finely dividing the crystal particles of the magnetic layer, the seed layer includes at least two or more layers of nonmagnetic films, and the intermediate layer formed of the material different from that of the nonmagnetic film is interposed between the nonmagnetic films. In measurement of the thermal stability of the magnetic recording medium, a head is used, the head includes a read/write element, and a write track width is twice or more as large as a read track width in the head.Type: GrantFiled: March 31, 2000Date of Patent: May 22, 2007Assignee: Hoya CorporationInventors: Hiroshi Tomiyasu, Teiichiro Umezawa, Genshichi Hata, Takashi Morikawa, Masato Kobayashi, Masashi Suzuki, Satoshi Yokota, Tsuyoshi Watanabe
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Patent number: 7208236Abstract: In a magnetic recording medium which comprises a substrate (1), a magnetic layer (3) formed on the substrate, a carbon-based protection layer (4) comprising carbon and formed on the magnetic layer, and a lubrication layer (5) formed on the carbon-based protection layer, the carbon-based protection layer comprises a hydrogenated carbon protection layer (4a) facing the magnetic layer and a nitrogenated carbon protection layer (4b) facing the lubrication layer. The hydrogenated carbon protection layer (4a) comprises carbon and hydrogen. The nitrogenated carbon protection layer (4b) includes no hydrogen but comprises carbon and nitrogen.Type: GrantFiled: May 6, 2005Date of Patent: April 24, 2007Assignees: Hoya Corporation, Hoya Magnetics Singapore Pte. Ltd.Inventors: Takashi Morikawa, Teiichiro Umezawa, Hiroshi Tomiyasu, Masafumi Ishiyama
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Publication number: 20070053106Abstract: A perpendicular magnetic recording medium 10 adapted to be mounted in a perpendicular magnetic recording type hard disk drive and including a disk-shaped disk base 12, a soft magnetic layer 14 formed on the disk base 12, and a perpendicular magnetic recording layer 16 formed on the soft magnetic layer 14, wherein, at respective portions of the soft magnetic layer 14, directional distribution of easy magnetization axes of magnetic particles included In each of the respective portions is isotropic with respect to respective directions in the main surface of the soft magnetic layer 14.Type: ApplicationFiled: July 13, 2006Publication date: March 8, 2007Inventors: Yoshiaki Sonobe, Shinichi Ishibashi, Masato Kobayashi, Teiichiro Umezawa
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Patent number: 7169487Abstract: In a magnetic recording medium including a glass substrate (1) having a principal surface on which at least a magnetic layer (4) is formed, the magnetic recording medium has a coercive force of 2500 oersted or more in a circumferential direction thereof. The principal surface of the glass substrate is provided with a texture having a predetermined surface roughness so that the magnetic layer is given circumferential magnetic anisotropy. The magnetic recording medium further includes a magnetic anisotropy inducing layer (2) formed between the glass substrate and the magnetic layer so that the magnetic recording medium has an oriented ratio (OR) of 1.1 or more. The oriented ratio (OR) is defined as a ratio of a magnetic characteristic in circumferential direction to another magnetic characteristic in the radial direction.Type: GrantFiled: December 16, 2002Date of Patent: January 30, 2007Assignees: Hoya Corporation, Hoya Magnetics Singapore Pte. Ltd.Inventors: Hisao Kawai, Teiichiro Umezawa, Hirotaka Tanaka, Masaki Uemura
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Patent number: 7081308Abstract: In a magnetic recording medium including a substrate (1) having a principal surface on which first and second magnetic layers (5 and 7) and a spacer layer (6) are at least formed, each of the first and the second magnetic layers being of a ferromagnetic material, the spacer layer being formed between the first and the second magnetic layers for inducing antiferromagnetic exchange interaction between the first and the second magnetic layers, the principal surface of the substrate is provided with concentric textures to have a predetermined surface roughness so that the spacer layer has a uniform thickness. The first magnetic layer is for controlling the antiferromagnetic exchange interaction.Type: GrantFiled: June 2, 2004Date of Patent: July 25, 2006Assignees: Hoya Corporation, Hoya Magnetics Singapore Pte. Ltd.Inventors: Hisao Kawai, Teiichiro Umezawa, Hirotaka Tanaka, Masaki Uemura
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Publication number: 20050208341Abstract: In a magnetic recording medium which comprises a substrate (1), a magnetic layer (3) formed on the substrate, a carbon-based protection layer (4) comprising carbon and formed on the magnetic layer, and a lubrication layer (5) formed on the carbon-based protection layer, the carbon-based protection layer comprises a hydrogenated carbon protection layer (4a) facing the magnetic layer and a nitrogenated carbon protection layer (4b) facing the lubrication layer. The hydrogenated carbon protection layer (4a) comprises carbon and hydrogen. The nitrogenated carbon protection layer (4b) includes no hydrogen but comprises carbon and nitrogen.Type: ApplicationFiled: May 6, 2005Publication date: September 22, 2005Inventors: Takashi Morikawa, Teiichiro Umezawa, Hiroshi Tomiyasu, Masafumi Ishiyama
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Patent number: 6946191Abstract: In a magnetic recording medium which comprises a substrate (1), a magnetic layer (3) formed on the substrate, a carbon-based protection layer (4) comprising carbon and formed on the magnetic layer, and a lubrication layer (5) formed on the carbon-based protection layer, the carbon-based protection layer comprises a hydrogenated carbon protection layer (4a) facing the magnetic layer and a nitrogenated carbon protection layer (4b) facing the lubrication layer. The hydrogenated carbon protection layer (4a) comprises carbon and hydrogen. The nitrogenated carbon protection layer (4b) includes no hydrogen but comprises carbon and nitrogen.Type: GrantFiled: February 24, 2003Date of Patent: September 20, 2005Assignees: Hoya Corporation, Hoya Magnetics Singapore PTEInventors: Takashi Morikawa, Teiichiro Umezawa, Hiroshi Tomiyasu, Masafumi Ishiyama
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Patent number: 6916558Abstract: In a magnetic disk having a glass substrate, an amorphous underlayer is formed on the glass substrate. A magnetic layer is formed on the amorphous underlayer. The glass substrate is provided with a texture formed to induce magnetic anisotropy in the magnetic layer. The amorphous underlayer contains a group IVa element on a glass substrate side and a group Va element on a magnetic layer side.Type: GrantFiled: February 17, 2004Date of Patent: July 12, 2005Assignees: Hoya Corporation, Hoya Magnetics Singapore Pte. Ltd.Inventors: Teiichiro Umezawa, Hiroshi Tomiyasu, Keiji Moroishi
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Publication number: 20040219394Abstract: In a magnetic recording medium including a substrate (1) having a principal surface on which first and second magnetic layers (5 and 7) and a spacer layer (6) are at least formed, each of the first and the second magnetic layers being of a ferromagnetic material, the spacer layer being formed between the first and the second magnetic layers for inducing antiferromagnetic exchange interaction between the first and the second magnetic layers, the principal surface of the substrate is provided with concentric textures to have a predetermined surface roughness so that the spacer layer has a uniform thickness. The first magnetic layer is for controlling the antiferromagnetic exchange interaction.Type: ApplicationFiled: June 2, 2004Publication date: November 4, 2004Applicant: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.Inventors: Hisao Kawai, Teiichiro Umezawa, Hirotaka Tanaka, Masaki Uemura
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Publication number: 20040213949Abstract: A magnetic disk 10 has a disk substrate 1 and an exchange coupling film 5 which is formed thereon and which has a first magnetic layer 5a, a second magnetic layer 5c, and a spacer layer 5b interposed between the first and the second magnetic layers 5a and 5c. The spacer layer 5b has a surface roughness Ra not greater than the thickness of the spacer layer 5b, where Ra is representative of a center-line-mean roughness.Type: ApplicationFiled: January 23, 2004Publication date: October 28, 2004Applicant: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.Inventors: Teiichiro Umezawa, Keiji Moroishi
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Publication number: 20040161577Abstract: In a magnetic disk having a glass substrate, an amorphous underlayer is formed on the glass substrate. A magnetic layer is formed on the amorphous underlayer. The glass substrate is provided with a texture formed to induce magnetic anisotropy in the magnetic layer. The amorphous underlayer contains a group IVa element on a glass substrate side and a group Va element on a magnetic layer side.Type: ApplicationFiled: February 17, 2004Publication date: August 19, 2004Applicants: HOYA CORORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.Inventors: Teiichiro Umezawa, Hiroshi Tomiyasu, Keiji Moroishi
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Patent number: 6759138Abstract: In a magnetic recording medium which includes a base body (1-4), first and second magnetic layers (5 and 7), each being of a ferromagnetic material, and a spacer layer (6) formed between the first and the second magnetic layers for inducing antiferromagnetic exchange interaction between the first and the second magnetic layers, the second magnetic layer located farther from the base body than the first magnetic layer includes a primary layer (72) and a secondary layer (71) located nearer to the base body than the primary layer. The primary layer has a primary anisotropic magnetic field while the secondary layer has a secondary anisotropic magnetic field which is smaller than the primary anisotropic magnetic field. The first magnetic layer is for controlling the antiferromagnetic exchange interaction.Type: GrantFiled: July 2, 2002Date of Patent: July 6, 2004Assignees: Hoya Corporation, Hoya Magnetics Singapore PTE, Ltd.Inventors: Hiroshi Tomiyasu, Keiji Moroishi, Teiichiro Umezawa, Kenji Ayama