Patents by Inventor Norikazu Tsumita
Norikazu Tsumita 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: 6627253Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. and 0.1 to 10 at. of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained. A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.Type: GrantFiled: July 3, 2001Date of Patent: September 30, 2003Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
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Patent number: 6335103Abstract: A magnetic recording medium including a substrate and a magnetic layer on the substrate which is a Co-based alloy including Pt and/or Ir, including at least one of Ti, Zr, Hr, V, Nb, Ta, Cr, Mo, W, Ge, and Si, and including oxygen. A magnetic memory apparatus including the magnetic recording medium.Type: GrantFiled: May 6, 1997Date of Patent: January 1, 2002Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
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Publication number: 20010053458Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.Type: ApplicationFiled: July 3, 2001Publication date: December 20, 2001Applicant: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
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Patent number: 6010794Abstract: A magnetic recording medium including a substrate and a magnetic layer on the substrate which is a Co-based alloy including Pt and/or Ir, including at least one of Ti, Zr, Hr, V, Nb, Ta, Cr, Mo, W, Ge, and Si, and including oxygen. A magnetic memory apparatus including the magnetic recording medium.Type: GrantFiled: May 6, 1997Date of Patent: January 4, 2000Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
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Patent number: 5665478Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.Type: GrantFiled: October 24, 1994Date of Patent: September 9, 1997Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
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Patent number: 5285343Abstract: There is provided a magnetic disk apparatus including at least one magnetic disk having a magnetic layer and a surface protective layer on a substrate; a magnetic head which faces the magnetic disk in a rotating state with a micro gap and is supported by a slider; rotating means for rotating the magnetic disk; and magnetic head positioning means for moving and positioning the magnetic head to a predetermined position on the magnetic disk, wherein a plurality of protrusions each having a flat surface are formed in at least a region on the surface of the magnetic disk where a contact start/stop operation can be executed, an area ratio of the protrusions per 1 mm.sup.2 lies within a range from 0.1 to 80%, a height of the protrusion of the maximum height among the protrusions lies within a range from 5 to 40 nm, and the magnetic layer is formed on the whole surface on the base plate.Type: GrantFiled: October 11, 1990Date of Patent: February 8, 1994Assignee: Hitachi, Ltd.Inventors: Hideaki Tanaka, Kenichi Gomi, Shoichi Sawahata, Maki Kondo, Masaki Ohura, Norikazu Tsumita, Katuo Uda, Yoshiki Kato, Yoshihiko Miyake, Toyoji Okuwaki, Noriaki Okamoto, Nobuo Nakagawa
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Patent number: 5236791Abstract: A magnetic recording medium that uses, as a protective coating layer provided on a magnetic layer for magnetically recording signals, a layer made of a nonmagnetic material consisting of two ore more elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and one or more elements of N, C, O, and B, or made of a magnetic material consisting of one or more elements of Co, Fe, Ni, and Gd, one or more elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and one or more elements of N, C, O, B, and Si is excellent in sliding endurance. When the protective coating layer is made of the nonmagnetic material, the magnetic recording medium is also excellent in corrosion resistance, and when the protective coating layer is made of the magnetic material, the spacing between a magnetic head and the magnetic recording medium can advantageously be made large. Both the cases are high in reliability, and suitable for high density magnetic recording.Type: GrantFiled: August 28, 1989Date of Patent: August 17, 1993Assignee: Hitachi, Ltd.Inventors: Yotsuo Yahisa, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Shinichiro Saitoh, Suzuki Hiroyuki, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Noriyuki Shige, Kazumasa Takagi
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Patent number: 5147732Abstract: Disclosed are longitudinal recording media comprising a composite magnetic film formed on a nonmagnetic substrate directly or through a nonmagnetic underlayer, in which all of magnetic thin films constituting the composite magnetic film are magnetically connected, the composite magnetic film has a single in-plane coercivity, and the in-plane coercivity is greater than the in-plane coercivity of a longitudinal magnetically anisotropic magnetic thin film constituting a magnetic thin film nearest to an information recording side among the magnetic thin films constituting the composite film.Type: GrantFiled: September 26, 1989Date of Patent: September 15, 1992Assignee: Hitachi, Ltd.Inventors: Yoshihiro Shiroishi, Takeo Yamashita, Sadao Hishiyama, Noriyuki Kumasaka, Yoshibumi Matsuda, Hiroyuki Suzuki, Kazumasa Takagi, Norikazu Tsumita, Masaki Ohura, Tomoyuki Ohno
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Patent number: 5143794Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W. Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.Type: GrantFiled: August 8, 1989Date of Patent: September 1, 1992Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Yotsuo Yahisa, Yoshibumi Matsuda, Norikazu Tsumita, Masaki Ohura, Takaaki Shirakura, Noriyuki Shige, Kazumasa Takagi
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Patent number: 4950548Abstract: The present invention relates to a magnetic recording medium for a magnetic disk unit or the like and, more particularly, to a magnetic recording medium having its recording layer made of a magnetic alloy film with uniform magnetic characteristics. The present magnetic recording medium comprises a non-magnetic substrate, at least two sputtered layers of chromium thin film having a bow-like columnar structure which chromium thin film is laminated on the substrate, another sputtered layer of a magnetic alloy thin film laminated on the chromium thin film, and a protective layer laminated on the magnetic alloy thin film. The present invention is effective in reducing modulation of regenerative output relatively independent of a texture roughness of the substrate.Type: GrantFiled: May 23, 1989Date of Patent: August 21, 1990Assignee: Hitachi, Ltd.Inventors: Kenji Furusawa, Katsuo Abe, Hiroyuki Kataoka, Tokuho Takagaki, Yoshihiro Shiroishi, Norikazu Tsumita
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Patent number: 4939045Abstract: Disclosed are a magnetic recording medium having a magnetic recording layer formed of a magnetic thin film in which rotational hysteresis integral R.sub.H is within a range of from 0.4 to 1.3 in the measurement by a torque magnetometer, and a continuous magnetic recording medium in which crystal grains are substantially randomly arranged on the upper surface of a magnetic recording layer or on the surface of a non-magnetic subbing layer, and in which each of the crystal grains is made to be in the form of an ellipsoid or needle and to have a length-ways axial ratio of a major axis to a minor axis not smaller than 2, more preferably, not smaller than 4.Type: GrantFiled: March 23, 1988Date of Patent: July 3, 1990Assignee: Hitachi, Ltd.Inventors: Kazuetsu Yoshida, Yoshihiro Shiroishi, Makoto Saito, Norikazu Tsumita, Takeo Yamashita, Hiroyuki Suzuki, Yasushi Kitazaki, Masaki Ohura, Sadao Hishiyama, Tomoyuki Ohno, Yoshibumi Matsuda, Kazumasa Takagi, Katsuhiro Kuroda, Sadanori Nagaike
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Patent number: 4883711Abstract: A magnetic recording medium in which a non-magnetic intermediate layer made of an alloy substantially composed of at least one element selected from the group consisting of Zr, Hf, Ta, Ti and Nb is disposed between a magnetic layer formed on a substrate and a non-magnetic overcoat layer formed on the magnetic layer. Since the impact shock resistance and the vibration resistance of the magnetic recording medium can be improved and the head-medium spacing of the magnetic disc apparatus can be decreased extremely by disposing the non-magnetic intermediate layer, it can provide a increase in the recording density, particularly, in a thin film type magnetic recording medium using a metallic magnetic thin film or metal oxide thin film as the magnetic layer. It can also improve the corrosion resistance in the case of a metallic magnetic thin film type medium.Type: GrantFiled: December 15, 1987Date of Patent: November 28, 1989Assignee: Hitachi, Ltd.Inventors: Yoshihiro Shiroishi, Sadao Hishiyama, Hiroyuki Suzuki, Tomoyuki Ohno, Yoshibumi Matsuda, Kazumasa Takagi, Norikazu Tsumita, Yasushi Kitazaki, Masaki Ohura, Sadanori Nagaike
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Patent number: 4833020Abstract: In a magnetic recording medium including an underlayer and a magnetic layer formed sequentially on a substrate, the underlayer is composed of a composite underlayer having an at least two-layered structure, the underlayer on the side of the substrate is made of a material providing low modulation to the magnetic recording medium while the underlayer on the side of the magnetic layer is made of a material providing a high S/N ratio to the medium. This makes it possible to obtain a magnetic recording medium having low modulation and high S/N ratio.Type: GrantFiled: January 28, 1988Date of Patent: May 23, 1989Assignee: Hitachi, Ltd.Inventors: Yoshihiro Shiroishi, Sadao Hishiyama, Hiroyuki Suzuki, Tomoyuki Ohno, Yoshibumi Matsuda, Kazumasa Takagi, Yoshio Gobara, Norikazu Tsumita, Masaki Ohura, Masaaki Hayashi
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Patent number: 4786553Abstract: A magnetic recording medium comprises a non-magnetic substrate and a thin magnetic film, the thin magnetic film being composed mainly of Co, Ni and at least one of Zr and Hf, and a concentration of Zr, Hf or Zr and Hf as contained in the thin magnetic film being 0.1 to 30% by atom on the basis of the total of Co and Ni, and has a considerably higher corrosion resistance than that of the conventional magnetic recording medium having a thin Co-Ni magnetic film.Type: GrantFiled: March 27, 1987Date of Patent: November 22, 1988Assignee: Hitachi, Ltd.Inventors: Yoshihiro Shiroishi, Sadao Hishiyama, Hiroyuki Suzuki, Norikazu Tsumita, Tsuneo Suganuma, Yoshio Gobara, Masaaki Hayashi, Makoto Sano, Takaaki Shirakura
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Patent number: 4743491Abstract: A perpendicular magnetic recording medium according to this invention comprises an electrically conductive underlayer formed on a non-magnetic substrate, in the case where no high permeability magnetic film is deposited, and a magnetic thin film having a perpendicular magnetic anisotrophy is formed thereon. In the case of a so-called double-layer structure including a high permeablilty magnetic film, on the non-magnetic substrate are formed the high permeablilty magnetic film, an intermediate film, and a magnetic thin film one on another in this order. The nearest neighbor's distance of atoms of the underlayer and the intermediate film is not smaller than 0.25 nm (2.5 .ANG.) and not greater than 0.32 nm (3.2 .ANG.) and they are made of at least one selected from the group consisting of V, Ru, Zn, Os, Rh, Ir, Mo, W, Re, Pd, Pt, Nb, Ta, Sn, Al, Au, Ag, Ti, nitrides and oxides of these elements.Type: GrantFiled: November 1, 1985Date of Patent: May 10, 1988Assignees: Hitachi, Ltd., Hitachi Maxell, Ltd.Inventors: Seiichi Asada, Hiroyuki Suzuki, Toshio Niihara, Kazuetsu Yoshida, Masaaki Futamoto, Yukio Honda, Norikazu Tsumita, Kazuo Shiiki
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Patent number: 4415262Abstract: A photomask is disclosed which is suitable for use in the one-mask method capable of forming a plurality of patterns with one exposure, and in which an opaque pattern having a predetermined form and a semi-transparent pattern having another predetermined form are formed on a transparent substrate, and the semi-transparent pattern is formed of an opaque film having a large number of fine through holes.Type: GrantFiled: January 18, 1982Date of Patent: November 15, 1983Assignee: Hitachi, Ltd.Inventors: Naoki Koyama, Youji Maruyama, Hiroshi Umezaki, Norikazu Tsumita, Yutaka Sugita
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Patent number: 4404233Abstract: The ion implantation is performed in a manner to vary the angle between an ion beam and an article to be implanted with ions, whereby it can be accomplished with remarkable ease while providing the impurity distribution which is flattened in the depthwise direction.Type: GrantFiled: January 13, 1981Date of Patent: September 13, 1983Assignee: Hitachi, Ltd.Inventors: Tadashi Ikeda, Norikazu Tsumita, Yutaka Sugita
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Patent number: 4344153Abstract: A magnetic bubble memory device and a method of fabricating the device are disclosed in which a conductor pattern lies at least between a film for maintaining magnetic bubbles therein, and a soft magnetic material pattern. Further, the magnetic bubble memory device can be formed precisely without suffering from errors due to mask alignment, by employing a mask provided with a plurality of patterns which are different in transmittance.Type: GrantFiled: April 13, 1979Date of Patent: August 10, 1982Assignee: Hitachi, Ltd.Inventors: Hideki Nishida, Hirozi Yamada, Hiroshi Umezaki, Yutaka Sugita, Norikazu Tsumita
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Patent number: 4288283Abstract: A method of forming a microscopic pattern wherein the object to be etched is overlaid with a film made of a material which is highly immune to etching and further provided with a reflection reducing film. Thus, the reflection of the irradiating ultraviolet rays by the underlying layer is effectively prevented.Type: GrantFiled: January 8, 1980Date of Patent: September 8, 1981Assignee: Hitachi, Ltd.Inventors: Hiroshi Umezaki, Hideki Nishida, Norikazu Tsumita, Hirozi Yamada, Katsuhiro Kaneko, Nagatugu Koiso