Patents by Inventor Yoshihito Yoshizawa

Yoshihito Yoshizawa 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: 5725686
    Abstract: A pulse transformer comprising a magnetic core formed of a thin strip of nanocrystalline soft magnetic alloy in which fine nanocrystalline grains having a grain size of not more than 50 nm occupy at least 50 volume % of the structure, characterized in that the AC relative initial magnetic permeability at -20.degree. C. and 50.degree. C. is not less than 50000.
    Type: Grant
    Filed: July 20, 1994
    Date of Patent: March 10, 1998
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Yoshio Bizen, Shin Nakajima, Shunsuke Arakawa
  • Patent number: 5658398
    Abstract: There is provided an alloy with ultrafine crystal grains excellent in corrosion resistance, at least 50% of the alloy structure being occupied by ultrafine crystal grains, the alloy having a surface layer containing hydroxide components in a total proportion of 65% or more based on oxide components.
    Type: Grant
    Filed: April 5, 1996
    Date of Patent: August 19, 1997
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Shunsuke Arakawa, Katsuhisa Sugimoto
  • Patent number: 5635828
    Abstract: An active filter circuit including a smoothing filter including a choke coil comprising a magnetic core composed of a nanocrystalline alloy and having a magnetic gap in at least one portion thereof and at least one conductive wire wound around the magnetic core, the nanocrystalline alloy having a composition of 0.1-3 atomic % of at least one element selected from the group consisting of Cu and Au, 1-7 atomic % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo and W, 10-17 atomic % of Si, and 4-10 atomic % of B, the balance being substantially Fe and inevitable impurities.
    Type: Grant
    Filed: November 23, 1994
    Date of Patent: June 3, 1997
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Tooru Abe, Shin Nakajima, Shunsuke Arakawa
  • Patent number: 5611871
    Abstract: A method for producing a nanocrystalline alloy wherein an amorphous alloy is heat-treated by keeping the temperature at a first heat treatment temperature higher than the crystallization temperature of the amorphous alloy for 0 to less than 5 minutes, and is cooled to room temperature at a cooling rate of 20.degree. C./min or more at least until the temperature falls to 400.degree. C. The amorphous alloy subjected to the first heat treatment may be further heat-treated at a second heat treatment temperature not higher than 500.degree. C. and lower than the first heat treatment temperature while applying a magnetic field. The nanocrystalline alloy produced by the method of the invention has a extremely high specific initial permeability as compared with the conventional nanocrystalline alloy, and is suitable for use in magnetic core of transformers, choke coils, etc.
    Type: Grant
    Filed: July 19, 1995
    Date of Patent: March 18, 1997
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Yoshio Bizen, Shin Nakajima, Shunsuke Arakawa
  • Patent number: 5591276
    Abstract: There is provided according to the present invention a magnetic alloy with ultrafine crystal grains having a composition represented by the general formula:Fe.sub.100-x-y M.sub.x B.sub.y (atomic %)wherein M represents at least one element selected from Ti, Zr, Hf, V, Nb, Mo, Ta, Cr, W and Mn, 4.ltoreq.x.ltoreq.15, 2.ltoreq.y.ltoreq.25, and 7.ltoreq.x+y.ltoreq.35, at least 50% of the alloy structure being occupied by crystal grains having an average grain size of 500 .ANG. or less, and the crystal grains being based on a bcc structure. It may further contain X (Si, Ge, P, Ga, etc.) and/or T (Au, Co, Ni, etc.). This magnetic alloy has an excellent saturation magnetic flux density, permeability and heat resistance.
    Type: Grant
    Filed: November 19, 1993
    Date of Patent: January 7, 1997
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Yoshio Bizen, Shigekazu Suwabe, Kiyotaka Yamauchi, Toshikazu Nishiyama
  • Patent number: 5567537
    Abstract: A magnetic core element for use in a thin antenna. The magnetic core element has a thickness of 25 .mu.m or less and is made of a particular amorphous alloy strip or a particular nano-crystalline alloy strip. A thin antenna having a laminated magnetic core made of the magnetic core elements is highly resistant to deformation and has a high Q-value.
    Type: Grant
    Filed: April 11, 1995
    Date of Patent: October 22, 1996
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Shunsuke Arakawa
  • Patent number: 5160379
    Abstract: An Fe-base soft magnetic alloy having the composition represented by the general formula:(Fe.sub.1-a M.sub.a).sub.100-x-y-z-.alpha.-.beta.-.gamma. Cu.sub.x Si.sub.y B.sub.z M'.sub..alpha. M".sub..beta. X.sub..gamma.wherein M is Co and/or Ni, M' is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, M" is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn and Re, X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, .alpha., .beta. and .gamma. respectively satisfy 0.ltoreq.a.ltoreq.0.5, 0.1.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.30, 0.ltoreq.z.ltoreq.25, 5.ltoreq.y+z.ltoreq.30, 0.1.ltoreq..alpha..ltoreq.30, .beta..ltoreq.10 and .gamma..ltoreq.10, at least 50% of the alloy structure being fine crystalline particles having an average particle size 1000 .ANG. or less.
    Type: Grant
    Filed: January 22, 1991
    Date of Patent: November 3, 1992
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Kiyotaka Yamauchi, Shigeru Oguma
  • Patent number: 5151137
    Abstract: A magnetic alloy with ultrafine crystal grains having a composition represented by the general formula:Co.sub.100.sub.-x-y-z-a-b Fe.sub.a M.sub.x B.sub.y X.sub.z T.sub.b (atomic %)wherein M represents at least one element selected from Ti, Zr, Hf, V, Nb, Mo, Ta, Cr, W and Mn, X represents at least one element selected from Si, Ge, P, Ga, Al and N, T represents at least one element selected from Cu, Ag, Au, platinum group elements, Ni, Sn, Be, Mg, Ca, Sr and Ba, 0<a.ltoreq.30, 2.ltoreq.x.ltoreq.15, 10.ltoreq.y.ltoreq.25, 0.ltoreq.z.ltoreq.10, 0<b.ltoreq.10, and 12<x+y+z+b.ltoreq.35. Such a magnetic alloy can be produced by producing an amorphous alloy having the above composition, and subjecting the resulting amorphous alloy to a heat treatment to cause crystallization, thereby providing the resulting alloy having a structure, at least 50% of which is occupied by crystal grains having an average grain size of 500 .ANG. or less.
    Type: Grant
    Filed: November 16, 1990
    Date of Patent: September 29, 1992
    Assignee: Hitachi Metals Ltd.
    Inventors: Yoshihito Yoshizawa, Yoshio Bizen, Kiyotaka Yamauchi, Toshikazu Nishiyama, Shigekazu Suwabe
  • Patent number: 5114503
    Abstract: A magnetic core comprised of an amorphous alloy ribbon wound into a toroidal shape, wherein the said amorphous alloy has a composition of the formula:(Co.sub.1-x-y-z Fe.sub.x Ni.sub.y Mn.sub.z).sub.100-a-b-c M.sub.a Si.sub.b B.sub.cwherein M is at least one element selected from the group consisting of Nb, Cr and Mo, and x, y, z, a, b and c are numbers which satisfy relations of 0<a.ltoreq.6, 13.ltoreq.b.ltoreq.16, 7.ltoreq.b.ltoreq.10, 0<x.ltoreq.0.1, 0.ltoreq.y.ltoreq.0.2 and 0.ltoreq.x.ltoreq.0.13 respectively, said amorphous alloy after heat treatment having a rectangular ratio Br/Bs of at least 80%, a Bs value in a range of 5 KG to 8 KG and a stress relief ratio of at least 75%.
    Type: Grant
    Filed: March 24, 1987
    Date of Patent: May 19, 1992
    Assignee: Hitachi Metals, Inc.
    Inventors: Yoshihito Yoshizawa, Kiyotaka Yamauchi
  • Patent number: 5069731
    Abstract: A low-frequency transformer including a magnetic core made of an alloy having the composition represented by the general formula:(Fe.sub.1-a M.sub.a).sub.100-x-y-z-.alpha. Cu.sub.x Si.sub.y B.sub.z M'.sub..alpha. (atomic %)wherein M is Co and/or Ni, M' is at least one element selected from the group consisting of Nb, W, Ta, Mo, Zr, Hf and Ti, and a, x, y, z and .alpha. respectively satisfy 0.ltoreq.a.ltoreq.0.3, 0.1.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.17, 4.ltoreq.z.ltoreq.17, 10.ltoreq.y+z.ltoreq.28 and 0.1.ltoreq..alpha..ltoreq.5, at least 50% of the alloy structure being occupied by fine crystal grains having an average grain size of 1000 .ANG. or less when measured by their maximum diameters. The alloy may further contain at least one element selected from the group consisting of Ge, P, C, Ga, Al and N.
    Type: Grant
    Filed: March 23, 1989
    Date of Patent: December 3, 1991
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Kiyotaka Yamauchi
  • Patent number: 4985089
    Abstract: Fe-base soft magnetic alloy powder and dust core having the composition represented by the general formula:(Fe.sub.1-a M.sub.a).sub.100-x-y-z-.alpha.-.beta.-.gamma. Cu.sub.x Si.sub.y B.sub.z M'.sub..alpha. M".sub..beta. X.sub..gamma.wherein M is Co and/or Ni, M' is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, M" is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn and Re, X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, .alpha., .beta. and .gamma. respectively satisfy 0.ltoreq.a.ltoreq.0.5, 0.1.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.30, 0.ltoreq.z.ltoreq.25, 0.ltoreq.y+z.ltoreq.35, 0.1.ltoreq..alpha..ltoreq.30, 0.ltoreq..beta..ltoreq.10 and 0.ltoreq..gamma..ltoreq.10, at least 50% of the alloy structure being fine crystalline particles having an average particle size of 500 .ANG. or less.
    Type: Grant
    Filed: July 25, 1988
    Date of Patent: January 15, 1991
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Kiyotaka Yamauchi
  • Patent number: 4945339
    Abstract: An anti-theft sensor marker is disclosed which has good sensitivity characteristics and which does not readily deteriorate due to bending stress. The marker is mainly composed of an alloy ribbon and is employed in an anti-theft system in which the stealing of a commodity previously marked by the marker is determined by detecting a magnetic field of a specific frequency with respect to an incident magnetic field intensity applied to a detection region through the alloy ribbon of the marker when the marker is disposed within the detection region.
    Type: Grant
    Filed: November 16, 1988
    Date of Patent: July 31, 1990
    Assignee: Hitachi Metals, Ltd.
    Inventors: Kiyotaka Yamauchi, Yoshihito Yoshizawa
  • Patent number: 4918555
    Abstract: A magnetic head having at least one magnetic gap in its magnetic path, which comprises an Fe-base solf magnetic alloy layer in the magnetic path, at least 50% of the structure of said alloy layer consisting of fine crystalline particles having a body-centered cubic structure and an average particle size of 500 .ANG. or less.
    Type: Grant
    Filed: July 25, 1988
    Date of Patent: April 17, 1990
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Kiyotaka Yamauchi, Toshikazu Nishiyama, Shigekazu Suwabe
  • Patent number: 4881989
    Abstract: An Fe-base soft magnetic alloy having the composition represented by the general formula:(Fe.sub.1-a M.sub.a).sub.100-x-y-z-.alpha.-.beta.-.gamma. Cu.sub.x Si.sub.y B.sub.z M'.sub.60 M".sub..beta. X.sub..gamma.wherein M is Co and/or Ni, M' is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, M" is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn and Re, X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, .alpha., .beta. and .gamma. respectively satisfy 0.ltoreq.a.ltoreq.0.5, 0.1.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.30, 0.ltoreq.z.ltoreq.25, 5.ltoreq.y+z.ltoreq.30, 0.1.ltoreq..alpha..ltoreq.30, .beta..ltoreq.10 and .gamma..ltoreq.10, at least 50% of the alloy structure being fine crystalline particles having an average particle size of 1000 .ANG. or less.
    Type: Grant
    Filed: October 1, 1987
    Date of Patent: November 21, 1989
    Assignee: Hitachi Metals, Ltd.
    Inventors: Yoshihito Yoshizawa, Kiyotaka Yamauchi, Shigeru Oguma
  • Patent number: 4871925
    Abstract: A high-voltage pulse generating apparatus having at least one magnetic switch comprising a magnetic core constituted by an Fe-base soft magnetic alloy ribbon wound in a toroidal form, the alloy having the composition represented by the general formula: ##STR1## wherein M is Co and/or Ni, M' is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, M" is at least one element selected from the group consisting of V, Cr, Mn, Al, elements in the platinum group, Sc, Y, rare earth elements, Au, Zn, Sn and Re, X is at least one element selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As, and a, x, y, z, .alpha., .beta. and .gamma. respectively satisfy 0.ltoreq.a.ltoreq.0.5, 0.1.ltoreq.x.ltoreq.3, 6.ltoreq.y.ltoreq.25, 3.ltoreq.z.ltoreq.15, 14.ltoreq.y+z.ltoreq.30, 1.ltoreq..alpha..ltoreq.10, 0.ltoreq..beta..ltoreq.10 and 0.ltoreq..gamma..ltoreq.
    Type: Grant
    Filed: October 24, 1988
    Date of Patent: October 3, 1989
    Assignee: Hitachi Metals, Ltd.
    Inventors: Kiyotaka Yamauchi, Yoshihito Yoshizawa, Shin Nakajima
  • Patent number: 4769091
    Abstract: A magnetic core comprised of an amorphous metal alloy having a composition represented by the formula:(Co.sub.1-a-b-c Fe.sub.a Mn.sub.b Mo.sub.c).sub.100-x-y Si.sub.x B.sub.y (in atomic %)wherein a, b, c, x and y are numbers which respectively satisfy relations 0.ltoreq.a.ltoreq.0.05, 0.03.ltoreq.b.ltoreq.0.08, 0.01.ltoreq.c.ltoreq.0.04, 0.04.ltoreq.b+c.ltoreq.0.10, 14.ltoreq.x.ltoreq.16 and 7.5.ltoreq.y.ltoreq.9.5, and the core is treated by a process including a step to keep the core at least one time at a temperature between 0.95.times.Tc and 150.degree. C. for a time of one hour to ten hours in a magnetic field, the direction of which is generally coincidental with the direction of the magnetic path in the core.
    Type: Grant
    Filed: August 10, 1987
    Date of Patent: September 6, 1988
    Assignee: Hitachi Metals Ltd.
    Inventors: Yoshihito Yoshizawa, Shin Nakajima, Kiyotaka Yamauchi
  • Patent number: 4757219
    Abstract: A lamination type of magnetostrictor incorporated with a mass of plural plates of amorphous metal alloy material laminated by means of a binder wherein the thickness of the plates is equal to or more than 80 .mu.m and the space factor of amorphous metal alloy in the mass is equal to or more than 80% and a manufacturing method thereof.
    Type: Grant
    Filed: January 30, 1986
    Date of Patent: July 12, 1988
    Assignees: Hitachi Metals, Ltd., Hitachi Ltd.
    Inventors: Kiyotaka Yamauchi, Yoshihito Yoshizawa, Kiyoshi Koyano