Patents by Inventor Sadao Hishiyama
Sadao Hishiyama 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: 5605733Abstract: A thin-film magnetic recording medium improves the magnetostatic and dynamic magnetic characteristics of the conventional magnetic recording media. In one embodiment, the substrate surface is textured in both the circumferential and radial directions. In further embodiments, a variety of underlayers (13) and crystal orientation control layers (17) are provided in accordance with specific parameters to control the crystal structure of the magnetic layer (14). Finally, an embodiment includes multiple magnetic layers (14, 19) having respectively different residual magnetic flux densities and thicknesses, but similar dot products of residual magnetic flux density and thickness.Type: GrantFiled: January 22, 1993Date of Patent: February 25, 1997Assignee: Hitachi, Ltd.Inventors: Akira Ishikawa, Sadao Hishiyama, Tomoo Yamamoto, Yoshihiro Shiroishi, Tomoyuki Ohno, Yotsuo Yahisa, Yukio Kato
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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: 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: 4842917Abstract: A magnetic recording medium having a magnetic film formed on a substrate directly or through an underlayer from an alloy containing Co as a principal component. The central line average surface roughness Ra and maximum surface roughness Rmax of the magnetic film in a direction perpendicular to the direction of magnetic recording are selected so as to fall within the ranges of 1 nm.ltoreq.Ra.ltoreq.20 nm and Rmax.ltoreq.25 Ra, respectively, and the in-plane magnetic anisotropy energy Ku of the magnetic film is selected to fall within the range of 0.ltoreq.Ku.ltoreq.8.times.10.sup.5 erg/cm.sup.3. Thus, it is possible to minimize the value of modulation which represents the degree of variation of read output on the same circumference of a magnetic disk. It is also possible to reduce the noise generated in read and write operations by forming the magnetic film so as have no crystallographic orientation.Type: GrantFiled: August 24, 1987Date of Patent: June 27, 1989Assignee: Hitachi, Ltd.Inventors: Tomoyuki Ohno, Yoshihiro Shiroishi, Sadao Hishiyama, Hiroyuki Suzuki, Takaaki Shirakura, Shinya Matsuoka, Makoto Sano, Takao Nakamura, Kazumasa Takagi, Tokuumi Fukazawa, Kenzo Susa
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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: 4792497Abstract: Disclosed is a magnetic recording medium of the magnetic metal thin-film type for longitudinal recording, in which the noise is reduced by selecting the value of maximum torque L (the product of magnetic anisotropy energy Ku and magnetic layer volume v; as measured by setting the axis of rotation in plane of the medium) and the value of magnetic flux .phi. (the product of saturation magnetization Ms and magnetic layer volume v) from a range defined by 0<L/(2.pi..multidot..phi..sup.2)<4.times.10.sup.5 (erg/emu.sup.2).Type: GrantFiled: January 28, 1988Date of Patent: December 20, 1988Assignee: Hitachi, Ltd.Inventors: Hiroyuki Suzuki, Yoshihiro Shiroishi, Sadao Hishiyama, Tomoyuki Ohno, Kazuetsu Yoshida, Shyuichi Kojima, Susumu Funamoto, Yasushi Kitazaki, Sakae Ohta, Hajime Aoi
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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: 4621030Abstract: A perpendicular magnetic recording medium free from spike noise having a high permeability magnetic material film, an antiferromagnetic material film and a perpendicularly oriented magnetic material film formed on a substrate in this order. Another high permeability magnetic material film may be formed between the antiferromagnetic material film and the perpendicularly oriented magnetic material film. During the formation of the antiferromagnetic material film, a magnetic field is applied in a direction of a track width.Type: GrantFiled: July 13, 1983Date of Patent: November 4, 1986Assignees: Hitachi, Ltd., Hitachi Maxell, Ltd.Inventors: Yasutaro Uesaka, Hideo Fujiwara, Sadao Hishiyama, Kazuo Shiiki
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Patent number: 4544591Abstract: In a perpendicular magnetic recording medium comprising a high permeability film and a perpendicular magnetization film which are laminated on a non-magnetic substrate, a perpendicular magnetic recording medium is provided wherein a permanent magnet film is further sandwiched between the non-magnetic substrate and the high permeability film, thereby eliminating a spike noise.Type: GrantFiled: September 30, 1983Date of Patent: October 1, 1985Assignees: Hitachi, Ltd, Hitachi Maxell, Ltd.Inventors: Yasutaro Uesaka, Sadao Hishiyama, Masahiro Kitada, Noboru Shimizu, Hideo Tanabe, Hideo Fujiwara
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Patent number: 3952567Abstract: A gas sensor comprising as a gas sensible material a spinel-type ferrite represented by the general formula AFe.sub.2 O.sub.4 in which A stands for at least one member selected from the group consisting of Li, Mg, Mn, Fe, Co, Ni, Cu, Zn and Pb is provided. In many cases, a catalyzer or a recovering agent need not be incorporated in this gas sensor, and it is characterized in that it is hardly influenced by moisture in the atmosphere.Type: GrantFiled: June 13, 1975Date of Patent: April 27, 1976Assignee: The Hitachi Heating Appliances Co., Ltd.Inventors: Kiminari Shinagawa, Sadao Hishiyama, Shinichi Ito, Kunifusa Kayama, Satoshi Taniguchi
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Patent number: 3947372Abstract: The temperature for preparation of garnet phase of the conventional yttrium or rare-earth iron garnet can be lowered by about several hundreds centigrade by substituting 24C site of the garnet by lead. Thus obtained lead-substituted yttrium or rare-earth iron garnet has greater specific Faraday rotation than lead-nonsubstituted yttrium or rare-earth iron garnet.Type: GrantFiled: July 25, 1973Date of Patent: March 30, 1976Assignee: Hitachi, Ltd.Inventors: Kiminari Shinagawa, Sadao Hishiyama, Hiroshi Takeuchi, Satoshi Taniguchi