Patents by Inventor Hisashi Yamasaki

Hisashi Yamasaki 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).

  • Patent number: 5576098
    Abstract: A thin film magnetic head includes an upper magnetic core film and a lower magnetic core film laminated one on another through a magnetic gap layer. The upper and lower magnetic core films are multilayer thin films, respectively, each of which is composed of a plurality of magnetic thin film layers and a plurality of non-magnetic thin film layers, alternately laminated one on another. The magnetic core films and have single domain structures, respectively, and the use of such magnetic core films realizes a thin film magnetic head having high permeability at high frequencies and improved high frequency characteristics and attains high recording density.
    Type: Grant
    Filed: July 6, 1993
    Date of Patent: November 19, 1996
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Yuko Arimoto, Takabumi Fumoto, Keiji Okubo, Osamu Saito, Toyoji Ataka, Hisashi Yamasaki
  • Patent number: 5552217
    Abstract: A magnetic recording medium includes a non-magnetic metal primary layer and a thin ferromagnetic alloy layer which are sequentially formed on a non-magnetic substrate in a laminated manner by sputtering. The thin ferromagnetic alloy layer is composed of not more than 15 at % of chromium, not more than 12 at % of platinum, 0.15 to 5.4 at % of a metal element selected from the group consisting of tantalum, hafnium, tungsten, zirconium and niobium, and the balance cobalt. The magnetic recording medium has a coercive force of higher than 1500 Oe and a squareness ratio of higher than 0.85.
    Type: Grant
    Filed: June 10, 1993
    Date of Patent: September 3, 1996
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Kiyoto Yamaguchi, Hisashi Yamasaki, Yoshifumi Matsui
  • Patent number: 5382301
    Abstract: A thin-film magnetic head is disclosed that includes a lower magnetic core and an upper magnet core formed on the surface of a substrate and connected together at a first end thereof, a magnetic gap is formed between the lower and upper magnetic cores at a second end thereof, and a coil-form electric conductive layer is located between the lower magnetic core and the upper magnet core. The lower and upper magnetic cores have a saturated magnetic flux density from 10,000 G to 18,000 G, while the magnetic permeability along the magnetic path of the magnetic head is 3,000 or higher at a frequency of 10 MHz. The unique characteristics of the magnetic head are obtained by heating an arrangement comprising the lower and upper magnetic cores, the magnetic gap layer, and the electric conductive layer to a temperature above 325.degree. C., and applying an external magnetic field greater than 0.
    Type: Grant
    Filed: October 15, 1992
    Date of Patent: January 17, 1995
    Assignee: Fuji Electric Co., Ltd.
    Inventors: Keiji Ohkubo, Yuko Arimoto, Hiroyuki Uwazumi, Hisashi Yamasaki
  • Patent number: 5306320
    Abstract: The object of the present invention is to provide a stoichiometric B1-type tantalum nitride and a sintered body thereof.A B1-type tantalum nitride and a sintered body thereof, wherein a stoichiometric B1-type tantalum nitride is produced typically according to the method of impact compression, having the properties (a) that the X ray diffraction substantially shows a pattern ascribed to the stoichiometric B1-type tantalum nitride alone but not others, (b) that the measured value of the lattice spacing D (h, k, l) has a deviation of 0.00013 nm or less from the corresponding value calculated based on the B1 structure, (c) that the lattice constant is 0.4335.about.0.4338 nm, (d) that the electron diffraction image substantially shows the spots particular to the stoichiometric B1-type tantalum nitride alone but not others and (e) the value of Z in TaN.sub.z is within a range of 0.96-1.01.
    Type: Grant
    Filed: December 8, 1992
    Date of Patent: April 26, 1994
    Assignee: Toshiba Tungaloy Co., Ltd.
    Inventors: Tsutomu Mashimo, Minoru Nishida, Susumu Yamaya, Hisashi Yamasaki
  • Patent number: 5201923
    Abstract: The object of the present invention is to provide a stoichiometric B1-type tantalum nitride and a sintered body thereof.A B1-type tantalum nitride and a sintered body thereof, wherein a stoichiometric B1-type tantalum nitride is produced typically according to the method of impact compression, having the properties (a) that the X-ray diffraction substantially shows a pattern ascribed to the stoichiometric B1-type tantalum nitride alone but not others, (b) that the measured value of the lattice spacing D (h, k, l) has a deviation of 0.00013 nm or less from the corresponding value calculated based on the B1 structure, (c) that the lattice constant is 0.4335.about.0.4338 nm, (d) that the electron diffraction image substantially shows the spots particular to the stoichiometric B1-type tantalum nitride alone but not others and (e) the value of Z in TaN.sub.z is within a range of 0.96-1.01.
    Type: Grant
    Filed: July 25, 1991
    Date of Patent: April 13, 1993
    Assignee: Toshiba Tungaloy Co., Ltd.
    Inventors: Tsutomu Mashimo, Minoru Nishida, Susumu Yamaya, Hisashi Yamasaki