Patents by Inventor Kiwamu Tanahashi
Kiwamu Tanahashi 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: 20030218834Abstract: In a magnetic storage apparatus having a magnetic recording medium, a drive unit for driving this medium in a prespecified recording direction, a magnetic head assembly including a recorder section and reproduction section, means for causing the magnetic head to move relatively with respect to the magnetic record medium, and a record/playback signal processor means for performing signal inputting to the magnetic head and for effecting reproduction of an output signal from the magnetic head, the reproduction section of said magnetic head is composed of a magnetic head of the magnetoresistance effect type, while said magnetic record medium is structured including a substrate and a magnetic layer formed thereover with one or several underlayers being sandwiched therebetween, wherein at least one of the underlayers is a specific layer that is made of amorphous or microcrystalline materials containing therein Ni as the principal or main component thereof and further containing at least one kind of element as selecType: ApplicationFiled: April 2, 2003Publication date: November 27, 2003Inventors: Tetsuya Kanbe, Ichiro Tamai, Yuzuru Hosoe, Kiwamu Tanahashi, Yoshio Takahashi, Fumiyoshi Kirino, Nagatugu Koiso, Satoshi Matsunuma
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Publication number: 20030211364Abstract: A magnetic recording system includes an in-plane magnetic recording medium having a magnetic layer fabricated on a single underlayer or on a plurality of underlayers respectively fabricated on a substrate; a driver unit for driving the in-plane magnetic recording medium in a write direction; a magnetic head having a read unit and a write unit; a unit for moving the magnetic head relative to the in-plane magnetic recording medium; and a read/write signal processing unit for reading an output signal from the magnetic head and writing an input signal to the magnetic recording media, wherein the read unit of the magnetic head is a magnetoresistive head and the single underlayer or at least one of the plurality of underlayers is made of Co-containing amorphous material or fine crystal material, or is made of alloy material, the alloy material having as the main components at least one element selected from a group consisting of Cr, Mo, V and Ta and containing at least one element selected from a group consisting oType: ApplicationFiled: June 3, 2003Publication date: November 13, 2003Inventors: Tetsuya Kanbe, Akira Ishikawa, Ichiro Tamai, Yotsuo Yahisa, Yuzuru Hosoe, Kiwamu Tanahashi, Yoshibumi Matsuda, Hiroyuki Kataoka, Toshinori Ono, Shinji Fukaya, Kazuhiro Ura, Naoto Endo, Tomoo Yamamoto
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Publication number: 20030203239Abstract: In a magnetic storage device, comprisingType: ApplicationFiled: April 15, 2003Publication date: October 30, 2003Applicant: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Yuzuru Hosoe, Ichiro Tamai, Yoshio Takahashi, Kiwamu Tanahashi, Satoshi Matsunuma, Yoshihiro Shiroishi
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Patent number: 6605374Abstract: The present invention provides a magnetic recording medium having a magnetic layer deposited on a substrate through a single-layer underlayer or a multilayer-underlayer, the magnetic layer includes magnetic crystal grains having an acicular structure or amorphous magnetic particles, an average grain size of the magnetic grain and a grain-size dispersion normalized by the average grain size are less than 16 nm and less than 0.5, respectively, a value Ku·v/kT which results from dividing a product of a magnetic anisotropy constant Ku and a volume v of the magnetic grain by a product of a Boltzmann constant k and an absolute temperature T is selected to be greater than 60, and a film thickness of the magnetic layer falls within twice of the average grain size.Type: GrantFiled: May 3, 2002Date of Patent: August 12, 2003Assignee: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Yoshio Takahashi, Akira Ishikawa, Ichiro Tamai, Yuzuru Hosoe, Yoshifumi Matsuda, Kiwamu Tanahashi, Tomoo Yamamoto
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Patent number: 6596420Abstract: A magnetic recording system includes an in-plane magnetic recording medium having a magnetic layer fabricated on a single underlayer or on a plurality of underlayers respectively fabricated on a substrate; a driver unit for driving the in-plane magnetic recording medium in a write direction; a magnetic head having a read unit and a write unit; a unit for moving the magnetic head relative to the in-plane magnetic recording medium; and a read/write signal processing unit for reading an output signal from the magnetic head and writing an input signal to the magnetic recording media, wherein the read unit of the magnetic head is a magnetoresistive head and the single underlayer or at least one of the plurality of underlayers is made of Co-containing amorphous material or fine crystal material, or is made of alloy material, the alloy material having as the main components at least one element selected from a group consisting of Cr, Mo, V and Ta and containing at least one element selected from a group consisting oType: GrantFiled: March 21, 2002Date of Patent: July 22, 2003Assignee: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Akira Ishikawa, Ichiro Tamai, Yotsuo Yahisa, Yuzuru Hosoe, Kiwamu Tanahashi, Yoshibumi Matsuda, Hiroyuki Kataoka, Toshinori Ono, Shinji Fukaya, Kazuhiro Ura, Naoto Endo, Tomoo Yamamoto
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Publication number: 20030118871Abstract: In a magnetic recording medium having Co-based alloy magnetic layer containing Pt formed on a substrate through an underlayer, by forming said underlayer with plural underlayers including double layer structure which is formed by piling up 1st underlayer of Cr-based alloy containing Ti and 2nd underlayer of Cr-based alloy containing at least one element selected from a group comprising Mo and W in this sequence, crystal grain diameter is decreased and then medium noise can be decreased, and c axis is oriented to in-plane direction and then high coercivity can be obtained, consequently the magnetic recording medium having high signal to noise ratio at high recording density region is obtained. Further a small size large capacity magnetic recording system can be provided by combination of said magnetic recording media with a MR (magnetoresistive) head.Type: ApplicationFiled: September 26, 2002Publication date: June 26, 2003Inventors: Yuzuru Hosoe, Yoshibumi Matsuda, Totsuo Yahisa, Kiwamu Tanahashi, Hiroyuki Suzuki, Koji Sakamoto, Akira Kato
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Patent number: 6583958Abstract: Provided are a low-noise, high-performance magnetic recording medium obtained by fining the size of the grains in a magnetic film, and a magnetic recording medium of low thermal demagnetization obtained by controlling the magnetic grain size in a small range. Simultaneously provided is a large-capacity magnetic storage system capable of high-density recording with a recording density exceeding 20 Gb/inch2. In a magnetic recording medium in which a magnetic layer is formed on a substrate via an underlayer, the magnetic layer is formed of an alloy containing cobalt as the main constituents and containing boron, chromium and germanium or containing phosphorus, chromium and germanium as additives of the alloy.Type: GrantFiled: September 1, 2000Date of Patent: June 24, 2003Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yuzuru Hosoe, Kiwamu Tanahashi
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Patent number: 6574060Abstract: In a magnetic storage apparatus having a magnetic recording medium, a drive unit for driving this medium in a prespecified recording direction, a magnetic head assembly including a recorder section and reproduction section, a way to cause the magnetic head to move relatively with respect to the magnetic record medium, and a record/playback signal processor for performing signal inputting to the magnetic head and for effecting reproduction of an output signal from the magnetic head, the reproduction section of said magnetic head is composed of a magnetic head of the magnetoresistance effect type, while said magnetic record medium is structured including a substrate and a magnetic layer formed thereover with one or several underlayers being sandwiched therebetween, wherein at least one of hte underlayers is a specific layer that is made of amorphous or microcrystalline materials containing therein Ni as the principal or main component thereof and further containing at least one kind of element as selected fromType: GrantFiled: March 6, 2001Date of Patent: June 3, 2003Assignee: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Ichiro Tamai, Yuzuru Hosoe, Kiwamu Tanahashi, Yoshio Takahashi, Fumiyoshi Kirino, Nagatugu Koiso, Satoshi Matsunuma
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Publication number: 20030099868Abstract: There is provided a perpendicular magnetic recording medium comprising a non-magnetic layer having a face-centered cubic structure, an antiferromagnetic layer provided on the non-magnetic layer, a soft magnetic underlayer provided on the antiferromagnetic layer, and a perpendicular recording layer provided on the soft magnetic underlayer, which magnetic recording medium makes it possible to realize a recording density not less than 5.0 Gb/in2 and makes the error rate thereof low while suppressing the spike noise.Type: ApplicationFiled: August 22, 2002Publication date: May 29, 2003Inventors: Kiwamu Tanahashi, Atsushi Kikugawa, Noboru Shimizu, Yukio Honda, Yuzuru Hosoe
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Publication number: 20030099866Abstract: Disclosed herein are a magnetic recording medium having a high coercive force and being capable of high-density writing/reading, a magnetic recording apparatus equipped with said magnetic recording medium, and a process for producing said magnetic recording medium.Type: ApplicationFiled: February 21, 2002Publication date: May 29, 2003Inventors: Yoshio Takahashi, Kiwamu Tanahashi, Yuzuru Hosoe, Ichiro Tamai
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Patent number: 6569545Abstract: A magnetic storage device has a recording density of over 5 gigabits per square inch. In the magnetic layer, the magnetic crystal grains of the granular structure are separated by a nonmagnetic phase. The typical crystal grain is in the approximate shape of a sphere or an ellipsoid. The thickness of the magnetic crystal grains, which is in the direction perpendicular to the surface of the film, is smaller than that of the thickness of the magnetic film. The ratio of the coercive force which is measured in the circumferential direction to the coercive force which is measured in the radial direction, which is the orientation ratio of the coercive force, is larger than 1.0, but preferably not greater than 3.0. Further, the area fraction of the magnetic grains having an extended axis within 30° from the circumferential direction is equal to or more than 45%.Type: GrantFiled: June 30, 1999Date of Patent: May 27, 2003Assignee: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Yuzuru Hosoe, Ichiro Tamai, Yoshio Takahashi, Kiwamu Tanahashi, Satoshi Matsunuma, Yoshihiro Shiroishi
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Patent number: 6544667Abstract: In a magnetic recording medium having Co-based alloy magnetic layer containing Pt formed on a substrate through an underlayer, by forming said underlayer with plural underlayers including double layer structure which is formed by piling up 1st underlayer of Cr-based alloy containing Ti and 2nd underlayer of Cr-based alloy containing at least one element selected from a group comprising Mo and W in this sequence, crystal grain diameter is decreased and then medium noise can be decreased, and c axis is oriented to in-plane direction and then high coercivity can be obtained, consequently the magnetic recording medium having high signal to noise ratio at high recording density region is obtained. Further a small size large capacity magnetic recording system can be provided by combination of said magnetic recording media with a MR (magnetoresistive) head.Type: GrantFiled: March 10, 2000Date of Patent: April 8, 2003Assignee: Hitachi, Ltd.Inventors: Yuzuru Hosoe, Yoshibumi Matsuda, Yotsuo Yahisa, Kiwamu Tanahashi, Hiroyuki Suzuki, Koji Sakamoto, Akira Kato
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Publication number: 20030053235Abstract: An object is to automatically detect the positions of spike noise, create a distribution diagram, and perform pass/fail decisions. The cross-correlation function of the signal waveform from a magnetic head 1 and a reference waveform simulating spike noise is used in extraction of spike noise. The number of peaks in the cross-correlation function exceeding a threshold value is counted, and quantitative evaluation of spike noise is performed.Type: ApplicationFiled: February 26, 2002Publication date: March 20, 2003Inventors: Atsushi Kikugawa, Kiwamu Tanahashi, Yukio Honda, Masaaki Futamoto, Yoshiyuki Hirayama
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Patent number: 6511761Abstract: In a magnetic storage apparatus including a recording medium having a magnetic layer, a seed layer and an underlayer formed on a substrate, a driver for driving the recording medium, a magnetic head having an inductive recording head and a magnetoresistive reproducing head, and a signal processing system for processing input signals to the magnetic head and output signals from the magnetic head, the seed layer comprises an amorphous alloy or a microcrystal alloy containing Ni, Ta and Zr, the underlayer comprises an alloy containing Cr as a main component and Ti, and the magnetic layer has a first magnetic layer in contact with the underlayer and a second magnetic layer on the first magnetic layer. The first magnetic layer comprises a Co—Cr—Pt alloy and the second magnetic layer comprises Co—Cr—Pt—B alloy, both of a substantially hexagonal close-packed structure.Type: GrantFiled: September 18, 2000Date of Patent: January 28, 2003Assignee: Hitachi, Ltd.Inventors: Kiwamu Tanahashi, Tetsuya Kanbe, Satoshi Matsunuma, Akira Ishikawa
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Publication number: 20020197514Abstract: Provided are a double-layer perpendicular magnetic recording medium having a high medium S/N at an areal recording density of 50 Gbits or more per square inch, and a magnetic storage apparatus having excellent reliability with a low error rate. The perpendicular magnetic recording medium is formed by sequentially laminating a domain control layer, an amorphous soft magnetic underlayer, an intermediate layer, and a perpendicular recording layer on a substrate. The domain control layer is a triple-layer film formed by laminating a first polycrystalline soft magnetic layer, a disordered antiferromagnetic layer, and a second polycrystalline soft magnetic layer from a substrate side.Type: ApplicationFiled: February 19, 2002Publication date: December 26, 2002Applicant: Hitachi, Ltd.Inventors: Kiwamu Tanahashi, Atsushi Kikugawa, Noboru Shimizu, Yukio Honda, Yuzuru Hosoe
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Publication number: 20020168547Abstract: The present invention provides a magnetic recording medium having a magnetic layer deposited on a substrate through a single-layer underlayer or a multilayer-underlayer, the magnetic layer includes magnetic crystal grains having an acicular structure or amorphous magnetic particles, an average grain size of the magnetic grain and a grain-size dispersion normalized by the average grain size are less than 16 nm and less than 0.5, respectively, a value Ku·v/kT which results from dividing a product of a magnetic anisotropy constant Ku and a volume v of the magnetic grain by a product of a Boltzmann constant k and an absolute temperature T is selected to be greater than 60, and a film thickness of the magnetic layer falls within twice of the average grain size.Type: ApplicationFiled: May 3, 2002Publication date: November 14, 2002Applicant: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Yoshio Takahashi, Akira Ishikawa, Ichiro Tamai, Yuzuru Hosoe, Yoshifumi Matsuda, Kiwamu Tanahashi, Tomoo Yamamoto
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Publication number: 20020150796Abstract: A magnetic recording system includes an in-plane magnetic recording medium having a magnetic layer fabricated on a single underlayer or on a plurality of underlayers respectively fabricated on a substrate; a driver unit for driving the in-plane magnetic recording medium in a write direction; a magnetic head having a read unit and a write unit; a unit for moving the magnetic head relative to the in-plane magnetic recording medium; and a read/write signal processing unit for reading an output signal from the magnetic head and writing an input signal to the magnetic recording media, wherein the read unit of the magnetic head is a magnetoresistive head and the single underlayer or at least one of the plurality of underlayers is made of Co-containing amorphous material or fine crystal material, or is made of alloy material, the alloy material having as the main components at least one element selected from a group consisting of Cr, Mo, V and Ta and containing at least one element selected from a group consisting oType: ApplicationFiled: March 21, 2002Publication date: October 17, 2002Inventors: Tetsuya Kanbe, Akira Ishikawa, Ichiro Tamai, Yotsuo Yahisa, Yuzuru Hosoe, Kiwamu Tanahashi, Yoshibumi Matsuda, Hiroyuki Kataoka, Toshinori Ono, Shinji Fukaya, Kazuhiro Ura, Naoto Endo, Tomoo Yamamoto
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Publication number: 20020122958Abstract: Disclosed are a double-layer perpendicular magnetic recording medium having a high medium S/N at a recording density of 50 Gbit or more per square inch and a magnetic storage apparatus with high reliability, which shows a low error rate. In the perpendicular magnetic recording medium in which a pre-coating layer, a soft magnetic underlayer, an intermediate layer, and a perpendicular recording layer are sequentially formed on a substrate, the soft magnetic underlayer contains Fe, Ta and C as main components, a Ta concentration is set to a range from 8 at % to 15 at %, and a ratio of a C concentration to the Ta concentration (C concentration/Ta concentration) is set to a range from 0.5 to 0.9.Type: ApplicationFiled: December 26, 2001Publication date: September 5, 2002Applicant: Hitachi, Ltd.Inventors: Kiwamu Tanahashi, Atsushi Kikugawa, Yukio Honda
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Patent number: 6403242Abstract: The present invention provides a magnetic recording medium having a magnetic layer deposited on a substrate through a single-layer underlayer or a multilayer-underlayer, the magnetic layer includes magnetic crystal grains having an acicular structure or amorphous magnetic particles, an average grain size of the magnetic grain and a grain-size dispersion normalized by the average grain size are less than 16 nm and less than 0.5, respectively, a value Ku·v/kT which results from dividing a product of a magnetic anisotropy constant Ku and a volume v of the magnetic grain by a product of a Boltzmann constant k and an absolute temperature T is selected to be greater than 60, and a film thickness of the magnetic layer falls within twice of the average grain size.Type: GrantFiled: March 14, 2000Date of Patent: June 11, 2002Assignee: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Yoshio Takahashi, Akira Ishikawa, Ichiro Tamai, Yuzuru Hosoe, Yoshifumi Matsuda, Kiwamu Tanahashi, Tomoo Yamamoto
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Patent number: 6403240Abstract: A magnetic recording system includes an in-plane magnetic recording medium having a magnetic layer fabricated on a single underlayer or on a plurality of underlayers respectively fabricated on a substrate; a driver unit for driving the in-plane magnetic recording medium in a write direction; a magnetic head having a read unit and a write unit; a unit for moving the magnetic head relative to the in-plane magnetic recording medium; and a read/write signal processing unit for reading an output signal from the magnetic head and writing an input signal to the magnetic recording media, wherein the read unit of the magnetic head is a magnetoresistive head and the single underlayer or at least one of the plurality of underlayers is made of Co-containing amorphous material or fine crystal material, or is made of alloy material, the alloy material having as the main components at least one element selected from a group consisting of Cr, Mo, V and Ta and containing at least one element selected from a group consisting oType: GrantFiled: May 19, 1997Date of Patent: June 11, 2002Assignee: Hitachi, Ltd.Inventors: Tetsuya Kanbe, Akira Ishikawa, Ichiro Tamai, Yotsuo Yahisa, Yuzuru Hosoe, Kiwamu Tanahashi, Yoshibumi Matsuda, Hiroyuki Kataoka, Toshinori Ono, Shinji Fukaya, Kazuhiro Ura, Naoto Endo, Tomoo Yamamoto