Patents by Inventor Akemi Hirotsune
Akemi Hirotsune 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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Patent number: 10276192Abstract: A magnetic recording medium includes an amorphous buffer layer, a hybrid layer including a barrier layer, and a texture control layer. The magnetic recording medium also includes a heat sink layer, an under layer, and a perpendicular recording layer.Type: GrantFiled: July 11, 2013Date of Patent: April 30, 2019Assignee: Western Digital Technologies, Inc.Inventors: Akemi Hirotsune, Ikuko Takekuma, Junichi Sayama
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Patent number: 9472228Abstract: A magnetic medium for perpendicular magnetic data recording having improved corrosion characteristics and reduced surface roughness. The magnetic medium includes an under-layer and a perpendicular magnetic recording layer formed over the under-layer. The under-layer can be formed of MgO and has an oxygen concentration that is greater at the perpendicular magnetic recording layer than it is away from the perpendicular magnetic recording layer.Type: GrantFiled: May 28, 2013Date of Patent: October 18, 2016Assignee: HGST Netherlands B.V.Inventors: Akemi Hirotsune, Ikuko Takekuma, Hiroyuki Matsumoto, Oleksandr Mosendz
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Publication number: 20160118071Abstract: In one embodiment, a perpendicular magnetic recording medium includes: a substrate; an underlayer positioned above the substrate; and a magnetic recording layer structure positioned above the underlayer, where the magnetic recording layer structure includes at least a first magnetic recording layer and a second magnetic recording layer, the second magnetic layer being positioned above first magnetic recording layer, where the first magnetic recording layer includes a first segregant material positioned between magnetic grains thereof, the first segregant material being primarily boron nitride (BN), and where the second magnetic recording layer includes a second segregant material positioned between the magnetic grains thereof, the second segregant material being primarily an oxide.Type: ApplicationFiled: October 23, 2014Publication date: April 28, 2016Applicant: HGST NETHERLANDS B.V.Inventors: Akemi Hirotsune, Ikuko Takekuma, Naoto Ito, Hiroyuki Matsumoto
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Patent number: 9117477Abstract: A magnetic medium for perpendicular magnetic data recording, having improved magnetic properties through use of a novel seed layer. The magnetic medium includes a substrate having a seed layer, a magnetic under-layer and a magnetic recording layer formed there-over. The seed layer includes an element selected from a first group of Cr, Co, Fe and Ni, and at least one element that is selected from the other elements of the first group or from a second group consisting of W, Mo and Ru. A buffer layer may be included between the substrate and the seed layer.Type: GrantFiled: May 8, 2013Date of Patent: August 25, 2015Assignee: HGST Netherlands B.V.Inventors: Akemi Hirotsune, Ikuko Takekuma, Hiroaki Nemoto
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Publication number: 20150017480Abstract: A magnetic recording medium includes an amorphous buffer layer, a hybrid layer including a barrier layer, and a texture control layer. The magnetic recording medium also includes a heat sink layer, an under layer, and a perpendicular recording layer.Type: ApplicationFiled: July 11, 2013Publication date: January 15, 2015Inventors: Akemi Hirotsune, Ikuko Takekuma, Junichi Sayama
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Publication number: 20140355156Abstract: A magnetic medium for perpendicular magnetic data recording having improved corrosion characteristics and reduced surface roughness. The magnetic medium includes an under-layer and a perpendicular magnetic recording layer formed over the under-layer. The under-layer can be formed of MgO and has an oxygen concentration that is greater at the perpendicular magnetic recording layer than it is away from the perpendicular magnetic recording layer.Type: ApplicationFiled: May 28, 2013Publication date: December 4, 2014Applicant: HGST Netherlands B.V.Inventors: Akemi Hirotsune, Ikuko Takekuma, Hiroyuki Matsumoto, Oleksandr Mosendz
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Publication number: 20140334039Abstract: A magnetic medium for perpendicular magnetic data recording, having improved magnetic properties through use of a novel seed layer. The magnetic medium includes a substrate having a seed layer, a magnetic under-layer and a magnetic recording layer formed there-over. The seed layer includes an element selected from a first group of Cr, Co, Fe and Ni, and at least one element that is selected from the other elements of the first group or from a second group consisting of W, Mo and Ru. A buffer layer may be included between the substrate and the seed layer.Type: ApplicationFiled: May 8, 2013Publication date: November 13, 2014Applicant: HGST Netherlands B.V.Inventors: Akemi Hirotsune, Ikuko Takekuma, Hiroaki Nemoto
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Patent number: 8703307Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a soft magnetic underlayer formed above a substrate, a lower seed layer formed above the soft magnetic underlayer, at least one upper seed layer formed above the lower seed layer, an interlayer formed above the at least one upper seed layer, a perpendicular recording layer formed above the interlayer, and a protective layer formed above the perpendicular recording layer, wherein the at least one upper seed layer comprises Ni or a Ni based alloy including N, and wherein the lower seed layer includes Ni and at least one element selected from a group consisting of: W and Cr. Other embodiments are described herein regarding perpendicular magnetic recording systems and methods of producing perpendicular magnetic media.Type: GrantFiled: October 12, 2010Date of Patent: April 22, 2014Assignee: HGST Netherlands B.V.Inventors: Akemi Hirotsune, Yotsuo Yahisa, Ichiro Tamai
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Patent number: 8592060Abstract: In one embodiment, a perpendicular magnetic recording medium includes a substrate, a soft-magnetic underlayer above the substrate, a seed layer above the soft-magnetic underlayer, a first intermediate layer above the seed layer, a second intermediate layer above the first intermediate layer, a recording layer above the second intermediate layer, and a protective layer above the recording layer. The second intermediate layer includes an Ru alloy having an element selected from a group consisting of: Ti in a range from about 20 at. % to about 50 at. %, Nb in a range from about 20 at. % to about 50 at. %, Al in a range from about 20 at. % to about 40 at. %, Ta in a range from about 30 at. % to about 50 at. %, and Si in a range about 20 at. % to about 40 at. %. Other magnetic media and systems using this media are described according to more embodiments.Type: GrantFiled: December 21, 2010Date of Patent: November 26, 2013Assignee: HGST Netherlands B.V.Inventors: Ichiro Tamai, Yotsuo Yahisa, Akemi Hirotsune, Kiwamu Tanahashi
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Patent number: 8514684Abstract: A multilayer optical disc which has three or more recording layers and enables easy positioning of a focused beam spot onto a particular recording layer in which a BCA is disposed. An inter-layer distance between a particular recording layer and a recording layer adjacent to the particular recording layer is larger than the other inter-layer distances in which, at the focused beam spot positioning, the focused beam spot traverses the said adjacent recording layer earlier than the other recording layer adjacent to the particular recording layer.Type: GrantFiled: August 10, 2011Date of Patent: August 20, 2013Assignee: Hitachi Consumer Electronics Co., Ltd.Inventors: Yoshinori Ishikawa, Harukazu Miyamoto, Akemi Hirotsune
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Patent number: 8483030Abstract: A multilayer optical disc which has three or more recording layers and enables easy positioning of a focused beam spot onto a particular recording layer in which a BCA is disposed. An inter-layer distance between a particular recording layer and a recording layer adjacent to the particular recording layer is larger than the other inter-layer distances in which, at the focused beam spot positioning, the focused beam spot traverses the said adjacent recording layer earlier than the other recording layer adjacent to the particular recording layer.Type: GrantFiled: August 10, 2011Date of Patent: July 9, 2013Assignee: Hitachi Consumer Electronics Co., Ltd.Inventors: Yoshinori Ishikawa, Harukazu Miyamoto, Akemi Hirotsune
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Patent number: 8315147Abstract: In a multilayer optical recording medium having at least three recording layers, an influence of interlayer crosstalk due to unnecessary light is suppressed. Each of the recording layers includes an information recording area, and the recording layers other than the nearest recording layer and the farthest recording layer when viewed from a light incident side include a first annular area having uneven patterns formed thereon, and a second annular area having uneven patterns formed thereon, the first annular area being adjacent to an inner side of the information recording area, the second annular area being adjacent to an outer side of the information recording area.Type: GrantFiled: April 9, 2009Date of Patent: November 20, 2012Assignee: Hitachi, Ltd.Inventors: Akemi Hirotsune, Shigeharu Kimura, Takahiro Kurokawa
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Publication number: 20120154948Abstract: In one embodiment, a perpendicular magnetic recording medium includes a substrate, a soft-magnetic underlayer above the substrate, a seed layer above the soft-magnetic underlayer, a first intermediate layer above the seed layer, a second intermediate layer above the first intermediate layer, a recording layer above the second intermediate layer, and a protective layer above the recording layer. The second intermediate layer includes an Ru alloy having an element selected from a group consisting of: Ti in a range from about 20 at. % to about 50 at. %, Nb in a range from about 20 at. % to about 50 at. %, Al in a range from about 20 at. % to about 40 at. %, Ta in a range from about 30 at. % to about 50 at. %, and Si in a range about 20 at. % to about 40 at. %. Other magnetic media and systems using this media are described according to more embodiments.Type: ApplicationFiled: December 21, 2010Publication date: June 21, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Ichiro Tamai, Yotsuo Yahisa, Akemi Hirotsune, Kiwamu Tanahashi
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Publication number: 20120099220Abstract: In one embodiment, a perpendicular magnetic recording medium includes a crystalline seed layer having a pseudo-hcp structure with stacking faults formed above a soft magnetic underlayer, a first interlayer comprising Ru and one of W, Ta, Mo, and Nb formed above the crystalline seed layer, a second interlayer formed above the first interlayer, and a magnetic recording layer formed above the second interlayer. The first interlayer has a W concentration between about 32 at % and 50 at %, Mo in a concentration between about 36 at % and 52 at %, Ta in a concentration between about 20 at % and 30 at %, or Nb in a concentration between about 7 at % and 30 at %. In another embodiment, a system includes a recording medium as described above, a magnetic head for reading from and/or writing to the medium, a head slider for supporting the head, and a control unit coupled to the head.Type: ApplicationFiled: October 21, 2010Publication date: April 26, 2012Applicant: Hitachi Global Storage Technologies Netherlands B. V.Inventors: Ichiro Tamai, Yotsuo Yahisa, Akemi Hirotsune
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Publication number: 20120087034Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a soft magnetic underlayer formed above a substrate, a lower seed layer formed above the soft magnetic underlayer, at least one upper seed layer formed above the lower seed layer, an interlayer formed above the at least one upper seed layer, a perpendicular recording layer formed above the interlayer, and a protective layer formed above the perpendicular recording layer, wherein the at least one upper seed layer comprises Ni or a Ni based alloy including N, and wherein the lower seed layer includes Ni and at least one element selected from a group consisting of: W and Cr. Other embodiments are described herein regarding perpendicular magnetic recording systems and methods of producing perpendicular magnetic media.Type: ApplicationFiled: October 12, 2010Publication date: April 12, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Akemi Hirotsune, Yotsuo Yahisa, Ichiro Tamai
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Patent number: 8134905Abstract: In an information memory apparatus having minute areas for storing information arranged in x, y and z directions three-dimensionally, parallel rays are irradiated to a memory area MA in a direction perpendicular to a z-axis to take projection images of the memory area MA while rotating the memory area MA around the z-axis little by little. The light rays irradiated at this time have a size which covers at least a direction of an x-y plane of the memory area. A computation unit PU finds data and addresses of minute areas distributed three-dimensionally by performing computation based upon the principle of computer tomography on the projection images. As for data writing, a change is given to optical transmissivity or light emission characteristics by irradiating laser light focused by a lens OL placed outside the memory area to a desired minute area and causing heat denaturation within the pertinent minute area.Type: GrantFiled: October 30, 2008Date of Patent: March 13, 2012Assignee: Hitachi, Ltd.Inventors: Takao Watanabe, Toshimichi Shintani, Takeshi Maeda, Akemi Hirotsune, Tomonori Sekiguchi
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Publication number: 20120044595Abstract: In one embodiment, a perpendicular magnetic recording medium (PMRM) includes a first interlayer comprising Ru or a Ru alloy, a second interlayer above the first interlayer comprising Ru or a Ru alloy, and a third interlayer formed between the first interlayer and the second interlayer that reduces an average cluster size of the second interlayer. In another embodiment, a PMRM includes a first interlayer comprising Ru or a Ru alloy, a second interlayer above the first interlayer comprising Ru or a Ru alloy, and a third interlayer formed between the first interlayer and the second interlayer that reduces an average cluster size of the second interlayer. The third interlayer has a thickness of between about 1.0 nm and about 3.0 nm and has a structure selected from a group consisting of: BCC, B2, C11b, L21, and D03. Other PMRMs and methods of fabrication are presented as well.Type: ApplicationFiled: August 23, 2010Publication date: February 23, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Yotsuo Yahisa, Ichiro Tamai, Akemi Hirotsune
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Patent number: 8089841Abstract: Regarding a signal recorded with a first frequency in a recording area on a specific first recording layer and a signal recorded with a second frequency different from the first frequency in a recording area on a second recording layer which might cause interlayer crosstalk in relation to the first recording layer, a reproducing signal measurement method for a multilayer optical recording medium having at least three recording layers includes reproducing the signal recorded in the recording area on the first recording layer, separating signals recorded respectively with the first and second frequencies, discriminating signal amplitude of the first frequency and a maximum value in signal amplitude of the second frequency, and calculating a signal amplitude ratio between them to measure interlayer crosstalk contained in the signal reproduced from the recording area on the first recording layer. Thus, the interlayer crosstalk quantity caused by unnecessary light can be measured quantitatively.Type: GrantFiled: May 15, 2008Date of Patent: January 3, 2012Assignee: Hitachi, Ltd.Inventors: Akemi Hirotsune, Junko Ushiyama, Hiroyuki Minemura, Takahiro Kurokawa, Harukazu Miyamoto
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Publication number: 20110299374Abstract: A multilayer optical disc which has three or more recording layers and enables easy positioning of a focused beam spot onto a particular recording layer in which a BCA is disposed. An inter-layer distance between a particular recording layer and a recording layer adjacent to the particular recording layer is larger than the other inter-layer distances in which, at the focused beam spot positioning, the focused beam spot traverses the said adjacent recording layer earlier than the other recording layer adjacent to the particular recording layer.Type: ApplicationFiled: August 10, 2011Publication date: December 8, 2011Applicant: Hitachi Consumer Electronics Co., Ltd.Inventors: Yoshinori ISHIKAWA, Harukazu MIYAMOTO, Akemi HIROTSUNE
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Patent number: 8040712Abstract: An information memory device using an electromagnetic-wave resonance phenomenon is provided to achieve both high density and long-period storage of stored data. Memory cells are three-dimensionally arranged in the inside of a solid-like medium which is not contacted with a surface of the medium, and the memory cell has resonance characteristics to electromagnetic waves depending on the space coordinates of the memory cell. For the medium, a material is selected so that an electromagnetic wave having the resonance frequency of the memory cell. By observing absorption spectra of the irradiated electromagnetic wave or emission spectra after the absorption, three-dimensional space coordinates of the memory cell are calculated.Type: GrantFiled: December 17, 2008Date of Patent: October 18, 2011Assignee: Hitachi, Ltd.Inventors: Takao Watanabe, Toshimichi Shintani, Takeshi Maeda, Akemi Hirotsune, Yoshitaka Bito