Patents by Inventor Kousaku Tamari
Kousaku Tamari 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: 6821618Abstract: A magnetic recording medium exhibiting a high coercive force and excellent squareness having a substrate, an underlayer formed on the substrate, and a spinel-type iron oxide thin film with maghemite as a main component formed on the underlayer. The spinel-type iron oxide thin film has a thickness (t) of 5 to 50 nm, is constituted by grains having an average grain size (D) of 5 to 30 nm, standard deviation of sizes of grain of not more than 4 nm and a ratio (D/t) of the average grain size (D) to the thickness (t) of less than 1.0, exhibits a coercive force of not less than 159 kA/m (2,000 Oe) and a coercive squareness ratio S* of not less than 0.5:1 in a longitudinal recording medium or a squareness ratio not less than 0.75:1 in a perpendicular recording medium.Type: GrantFiled: July 1, 2002Date of Patent: November 23, 2004Assignee: Toda Kogyo CorporationInventors: Jun Koujima, Teruaki Santoki, Kenichi Nakata, Takanori Doi, Masaaki Maekawa, Kousaku Tamari
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Patent number: 6753077Abstract: A magnetic recording medium including a substrate and formed on the substrate a maghemite thin film having a surface roughness represented by a center line mean roughness Ra of 0.1 to 1.0 nm, and a coercive force squareness S* value of not less than 0.50. This magnetic recording medium exhibits excellent magnetic properties, especially, coercive force squareness S* value and a more enhanced surface smoothness.Type: GrantFiled: December 22, 2000Date of Patent: June 22, 2004Assignee: Toda Kogyo CorporationInventors: Kenichi Nakata, Kousaku Tamari, Jun Koujima, Teruaki Santoki
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Publication number: 20030008176Abstract: A magnetic recording medium, comprising: a substrate; an underlayer formed on the substrate; and a spinel-type iron oxide thin film comprising maghemite as a main component formed on the underlayer,Type: ApplicationFiled: July 1, 2002Publication date: January 9, 2003Inventors: Jun Koujima, Teruaki Santoki, Kenichi Nakata, Takanori Doi, Masaaki Maekawa, Kousaku Tamari
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Publication number: 20020094458Abstract: A magnetic recording medium, comprising: a substrate; and a maghemite thin film formed on the substrate, having a surface roughness represented by a center line mean roughness Ra of 0.1 to 1.0 nm, and a coercive force squareness S* value of not less than 0.50.Type: ApplicationFiled: December 22, 2000Publication date: July 18, 2002Inventors: Kenichi Nakata, Kousaku Tamari, Jun Koujima, Teruaki Santoki
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Patent number: 6268024Abstract: A magnetic recording medium is prepared by forming on a plastic substrate, a nickel oxide underlayer having a plane (200) which is predominantly oriented in parallel with the surface of the plastic substrate, then forming on the nickel oxide underlayer at a substrate temperature of less 240° C., a cobalt-containing magnetite thin film having a plane (400) which is predominantly oriented in parallel with the surface of the plastic substrate, and finally oxidizing the cobalt-containing magnetite thin film in a plasma-activated oxygen atmosphere containing a rare gas at a substrate temperature of less than 240° C. while incorporating the rare gas into oxygen. This results in a cobalt-containing maghemite thin film as a perpendicular magnetic film having a spacing of a plane (400) of not more than 2.082 Å. The magnetic recording medium so produced is useful for high-density recording using a plastic substrate.Type: GrantFiled: March 25, 1999Date of Patent: July 31, 2001Assignee: Toda Kogyo CorporationInventors: Takanori Doi, Kousaku Tamari, Yasuo Kakihara, Kenichi Nakata, Mitsuru Matsuura, Setsuo Yamamoto
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Patent number: 6221519Abstract: A magnetic recording medium comprising: a plastic substrate; a nickel oxide underlayer formed on said substrate; and a cobalt-containing maghemite thin film formed on said nickel oxide underlayer, containing cobalt at a molar ratio of cobalt to iron of 0.01:1 to 0.1:1, and having either a spacing of a plane (311) of not more than 2.510 Å, a spacing of a plane (222) of not more than 2.415 Å or a spacing of a plane (220) of not more than 2.950 Å, a ratio value of an X-ray diffraction pattern peak intensity of either of the planes (311), (222) and (220) of said cobalt-containing maghemite thin film to an X-ray diffraction pattern peak intensity of the plane (400) thereof being more than 0.5. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.Type: GrantFiled: March 19, 1999Date of Patent: April 24, 2001Assignee: Toda Kogyo CorporationInventors: Takanori Doi, Kousaku Tamari, Yasuo Kakihara, Kenichi Nakata, Mitsuru Matsuura, Setsuo Yamamoto
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Patent number: 6187462Abstract: A magnetic recording medium of the present invention comprises: a plastic substrate; and a cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, and having either a spacing of a plane (311) of not more than 2.510 Å, a spacing of a plane (222) of not more than 2.415 Å or a spacing of a plane (220) of not more than 2.950 Å; and has a coercive force of not less than 2,000 Oe. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.Type: GrantFiled: March 19, 1999Date of Patent: February 13, 2001Assignee: Toda Kogyo CorporationInventors: Takanori Doi, Kousaku Tamari, Yasuo Kakihara, Kenichi Nakata, Mitsuru Matsuura, Setsuo Yamamoto
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Patent number: 6165608Abstract: A magnetic recording medium of the present invention comprises:a substrate; anda cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having a coercive force of not less than 1,800 Oe.Such a magnetic recording medium has as high a coercive force as possible, specifically not less than 1,800 Oe, and exhibits an excellent stability independent to change in passage of time and a large output in a high recording frequency region.Type: GrantFiled: September 29, 1998Date of Patent: December 26, 2000Assignee: Toda Kogyo CorporationInventors: Kousaku Tamari, Takanori Doi, Yasuo Kakihara, Kenichi Nakata
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Patent number: 6159594Abstract: A magnetic recording medium of the present invention comprises:a substrate;a nickel oxide underlayer formed on said substrate; anda cobalt-containing maghemite thin film formed on said nickel oxide underlayer, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having the ratio of either of X-ray diffraction spectrum peak intensities of the (311), (222) or (220) planes of said cobalt-containing maghemite thin film to an X-ray diffraction spectrum peak intensity of the (400) plane of more than 0.5:1.Such a magnetic recording medium has a higher coercive force, a higher saturation magnetization, less amount of noise generated, a large output in a high recording frequency region and less distortion of a reproduced waveform, and is suitable for use in current magnetic recording systems in which a ring-type magnetic write head is used.Type: GrantFiled: September 29, 1998Date of Patent: December 12, 2000Assignee: Toda Kogyo CorporationInventors: Kousaku Tamari, Takanori Doi, Yasuo Kakihara, Kenichi Nakata
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Patent number: 5851582Abstract: The disclosure describes a magnetic recording medium comprising:a substrate;an NiO primary layer which is formed on the substrate and in which the plane (200) is substantially oriented in parallel with the surface of the substrate; anda Co-containing maghemite thin film which is formed on the NiO primary layer and in which the plane (400) is substantially oriented in parallel with the surface of the substrate, the molar ratio of Co to Fe is not less than 0.01 to less than 0.10, and the spacing of the plane (400) is not more than 2.082 .ANG..Type: GrantFiled: October 7, 1996Date of Patent: December 22, 1998Assignee: Toda Kogyo CorporationInventors: Kousaku Tamari, Takanori Doi
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Patent number: 5628953Abstract: Disclosed herein is a perpendicular magnetic film comprising a spinel thin film which is formed on a substrate, which contains Fe as the main ingredient and further contains Co and Ni, and which has a coercive force of less than 3000 Oe, the plane (400) thereof being predominantly oriented in parallel with said substrate, the spacing of the plane (400) being not more than 2.082 .ANG., the molar ratio of Co to Fe being 0.005 to 0.32 and the molar ratio of Ni to Co being at least 0.6.Type: GrantFiled: December 7, 1995Date of Patent: May 13, 1997Assignee: Toda Kogyo CorporationInventor: Kousaku Tamari
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Patent number: 5601904Abstract: The disclosure describes a magnetic recording medium comprising:a substrate;an NiO primary layer which is formed on the substrate and in which the plane (200) is substantially oriented in parallel with the surface of the substrate; anda Co-containing maghemite thin film which is formed on the NiO primary layer and in which the plane (400) is substantially oriented in parallel with the surface of the substrate, the molar ratio of Co to Fe is not less than 0.01 to less than 0.10, and the spacing of the plane (400) is not more than 2.082 .ANG..Type: GrantFiled: March 15, 1995Date of Patent: February 11, 1997Assignee: Toda Kogyo CorporationInventors: Kousaku Tamari, Takanori Doi
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Patent number: 5589261Abstract: Disclosed herein is a perpendicular magnetic film comprising at least two of a (A)/(B) unit or (B)/(A) unit obtained by disposing a spinel type crystal layer (A) represented by the following general formula:A.sub.x Fe.sub.3-x O.sub.4(wherein A is a transition metal, and x is not more than 1), anda spinel type crystal layer (B) represented by the following general formula:B.sub.y Co.sub.3-y O.sub.4(wherein B is a transition metal, and y is not more than 1), in the order of (A) and (B) or (B) and (A).Type: GrantFiled: October 24, 1994Date of Patent: December 31, 1996Assignee: Toda Kogyo CorporationInventor: Kousaku Tamari
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Patent number: 5580671Abstract: Disclosed herein is a perpendicular magnetic film comprising a Co-containing .gamma.-Fe.sub.2 O.sub.3 film formed on a substrate in which the plane (400) is predominantly oriented in parallel with said substrate, the molar ratio of Co to Fe is between 0.01 and 0.32, the spacing of said plane (400) is not more than 2.084 .ANG., and the optical absorption coefficient at 700 nm is not more than 2.5 .mu.m.sup.-1.Type: GrantFiled: August 24, 1993Date of Patent: December 3, 1996Assignee: Toda Kogyo CorporationInventors: Kousaku Tamari, Takanori Doi
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Patent number: 5496631Abstract: Disclosed herein is a perpendicular magnetic film comprising a spinel thin film which is formed on a substrate, which contains Fe as the main ingredient and further contains Co and Ni, and which has a coercive force of less than 3000 Oe, the plane (400) thereof being predominantly oriented in parallel with said substrate, the spacing of the plane (400) being not more than 2.082 .ANG., the molar ratio of Co to Fe being 0.005 to 0.32 and the molar ratio of Ni to Co being at least 0.6.Type: GrantFiled: November 29, 1993Date of Patent: March 5, 1996Assignee: Toda Kogyo CorporationInventor: Kousaku Tamari
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Acicular magnetic iron based alloy particles for magnetic recording and method of producing the same
Patent number: 5238483Abstract: Disclosed herein are acicular magnetic iron based alloy particles for magnetic recording, containing 1.5 to 10 mol % of B based on Fe (calculated as B) and 1.5 to 10 mol % of Co based on Fe (calculated as Co) in the vicinity of the surfaces of said particles and having a saturation magnetization of not less than 125 emu/g and an S.F.D. value of not more than 0.50, and a process for producing the same.Type: GrantFiled: July 29, 1992Date of Patent: August 24, 1993Assignee: Toda Kogyo CorporationInventors: Akio Mishima, Mamoru Tanihara, Yasutaka Ota, Hirofumi Kawasaki, Kenji Okinaka, Kunio Ikemoto, Kousaku Tamari, Kohji Mori, Norimichi Nagai -
Acicular magnetic iron based alloy particles for magnetic recording and method of producing the same
Patent number: 5156922Abstract: Disclosed herein are acicular magnetic iron based alloy particles for magnetic recording, containing 1.5 to 10 mol % of B based on Fe (calculated as B) and 1.5 to 10 mol % of Co based on Fe (calculated as Co) in the vicinity of the surfaces of said particles and having a saturation magnetization of not less than 125 emu/g and an S.F.D. value of not more than 0.50, and a process for producing the same.Type: GrantFiled: July 8, 1991Date of Patent: October 20, 1992Assignee: Toda Kogyo CorporationInventors: Akio Mishima, Mamoru Tanihara, Yasutaka Ota, Hirofumi Kawasaki, Kenji Okinaka, Kunio Ikemoto, Kousaku Tamari, Kohji Mori, Norimichi Nagai -
Patent number: 5009712Abstract: Disclosed herein is a non-magnetic pigment comprising plate-like potassium ferrite particles having an average diameter of 0.03-30.0 .mu.m and a process for producing the same.Type: GrantFiled: December 14, 1989Date of Patent: April 23, 1991Assignee: Toda Kogyo Corp.Inventors: Kousaku Tamari, Tsutomu Katamoto