Patents by Inventor Masao Shigeta
Masao Shigeta 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: 6310837Abstract: The invention is a magnetic recording medium which is effectively protected against forgery by the alteration of recorded data, and a method for carrying out writing and reading on this magnetic recording medium. The magnetic recording medium of the invention comprises a recording material composed of a crystalline alloy containing Fe and Al . In the recoding material, the total amount of Fe and Al is at least 90 at % and the atomic ratio Al/(Fe+Al) ranges from 0.30 to 0.45. The recording material changes from a disordered phase to an ordered phase by heating. The recording material has a saturation magnetization of at least 45 emu/g prior to heating and lowers its saturation magnetization by at least 35 emu/g upon heating. Dark regions are observable in a bright-field image of the recording material by transmission electron microscopy, the dark regions accounting for 15-60% of the recording material in areal ratio and having a maximum breadth of 10-200 nm.Type: GrantFiled: October 13, 1998Date of Patent: October 30, 2001Assignees: TDK Corporation, Tokyo Magnetic Printing Co., Ltd.Inventors: Tsutomu Chou, Masao Shigeta, Masahiro Karatsu, Mari Fujii, Chikara Ishizaka, Katsumi Saito, Katsuhiko Wakayama, Shohei Mimura, Masahiro Ito
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Patent number: 6202926Abstract: A magnetic recording medium, and methods of making and reading the same, including on at least a portion of a substrate an irreversible recording layer which contains an irreversible recording material undergoing an irreversible change of saturation magnetization upon heating. The invention involves the steps of previously heating the irreversible recording layer to form an initial heated region in which a plurality of heated bars whose saturation magnetization has been irreversibly changed are arrayed in a bar code pattern, and converting unheated bars disposed between the heated bars into a heated state for changing the array pattern of heated bars, thereby recording the information.Type: GrantFiled: February 4, 1999Date of Patent: March 20, 2001Assignees: Tokyo Magnetic Printing Co., Ltd., TDK CorporationInventors: Masahiro Ito, Shohei Mimura, Masao Shigeta, Tsutomu Chou
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Patent number: 6029895Abstract: A magnetic recording medium, and a method of making the same, including an irreversible recording layer which undergoes an irreversible change of saturation magnetization upon heating. The magnetic recording medium includes on at least a portion of a substrate an irreversible recording layer which contains an irreversible recording material undergoing an irreversible change of saturation magnetization upon heating. The irreversible recording layer includes at least in part a fixed information recording region for recording the fixed information of the medium. In the fixed information recording region, a plurality of heated bars whose saturation magnetization has been irreversibly changed are arrayed substantially parallel to each other. The array pattern of the heated bars or the array pattern of unheated bars disposed between adjacent ones of the heated bars contains the fixed information encoded in a frequency modulation process or phase modulation process.Type: GrantFiled: February 4, 1999Date of Patent: February 29, 2000Assignees: Tokyo Magnetic Printing Co., Ltd., TDK CorporationInventors: Masahiro Ito, Shohei Mimura, Masao Shigeta, Tsutomu Chou
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Patent number: 5252148Abstract: A soft magnetic alloy having a composition of general formula:(Fe.sub.1-a Ni.sub.a).sub.100-x-y-z-p-q Cu.sub.x Si.sub.y B.sub.z Cr.sub.p M.sup.1.sub.q (I)wherein M.sup.1 is V or Mn or a mixture of V and Mn, 0.ltoreq.a.ltoreq.0.5, 0.1.ltoreq.x.ltoreq.5, 6.ltoreq.y.ltoreq.20, 6.ltoreq.z.ltoreq.20, 15.ltoreq.y+z.ltoreq.30, 0.5.ltoreq.p.ltoreq.10, and 0.5.ltoreq.q.ltoreq.10 and possessing a fine crystalline phase is suitable as a core, especially a wound core and a compressed powder core.Type: GrantFiled: August 10, 1992Date of Patent: October 12, 1993Assignee: TDK CorporationInventors: Masao Shigeta, Asako Kajita, Ippo Hirai, Tsutomu Choh
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Patent number: 5211767Abstract: Soft magnetic alloy comprising Fe, a vitrifying element (Si and B), and Cu, and containing a crystalline phase shows a low magnetic permeability of up to 3,000 at 100 kHz. Magnetic cores formed therefrom have low permeability, a wide unsaturation region, and iso.permeability without forming a gap and find application in choke coils and transformers.Type: GrantFiled: March 17, 1992Date of Patent: May 18, 1993Assignee: TDK CorporationInventors: Masao Shigeta, Asako Kajita
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Patent number: 5207841Abstract: Soft magnetic powder comprising flat soft magnetic particles of an alloy having a composition defined and encompassed by polygon ABCDE in a Fe-Si-Cr ternary composition diagram of FIG. 1 or polygon JKLMN in a Fe-Si-Al ternary composition diagram of FIG. 4 is suitable for use in magnetic shields. The flat soft magnetic particles are prepared by furnishing alloy particles having a predetermined composition, flattening them, and heat treating the flat particles to develop a peak corresponding to plane index (002) in an X-ray diffraction diagram thereof.Type: GrantFiled: April 5, 1991Date of Patent: May 4, 1993Assignee: TDK CorporationInventors: Masao Shigeta, Asako Kajita, Ippo Hirai
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Patent number: 4923533Abstract: A powder comprising flakes of magnetically soft amorphous alloy having an average thickness of 0.01-1 .mu.m and an aspect ratio of 10-10,000 is blended with a binder to form a coating composition from which a magnetic shield is fabricated. The alloy is basically an Fe-B-Si ternary alloy in which iron may be partially replaced by another metal.Type: GrantFiled: July 29, 1988Date of Patent: May 8, 1990Assignees: TDK Corporation, Tokyo Magnetic Printing Company, Ltd.Inventors: Masao Shigeta, Tsutomu Choh, Hiroyoshi Shimizu, Ippo Hirai, Shohei Mimura, Atsushi Makimura, Hiroshi Hosaka
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Patent number: 4739263Abstract: A direction sensor includes at least one sensor element including a ring-shaped core formed from at least one flexible wire made of zero-magnetostrictive amorphous magnetic material, two pairs of series connected coils spaced from each other at equal intervals about the core for sensing an external magnetic field, with the core being formed by threading the wires through the coils, the coils being excited by an alternating frequency f, wherein voltages of frequency f are produced across each pair of coils; and a process circuit for providing a differential voltage between the voltages of frequency f produced across each pair of coils.Type: GrantFiled: July 2, 1986Date of Patent: April 19, 1988Assignee: TDK CorporationInventors: Kaneo Mohri, Masao Shigeta
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Patent number: 4637843Abstract: The present invention relates to the core of a noise filter.Conventionally, ferrite or iron powder is used as the core of a noise filter. Some patent publications disclose the core of a noise filter made of an amorphous magnetic alloy.An amorphous magnetic alloy which as a low pulse-noise resistance deterioration percentage is that on or within the curve X and Y of FIG. 3.Type: GrantFiled: May 3, 1985Date of Patent: January 20, 1987Assignee: TDK CorporationInventors: Suguru Takayama, Masao Shigeta
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Patent number: 4621248Abstract: The present invention relates to a core of magnetic amorphous alloy. A thin strip of such alloy is wound and then cut to provide, e.g., C-shaped pieces. A pair of C-shaped pieces is assembled to provide the core. Conventionally, the magnetic properties, e.g., the watt loss, of the core are impaired at the cut ends of a thin strip due to the formation of burrs.The present invention is characterized by providing the cut ends with a thickness substantially the same as the thickness of the non-cut portion of the thin strip and by polishing the cut ends substantially parallel to the major surface of the thin strip, thereby improving the magnetic properties of the core.Type: GrantFiled: June 18, 1984Date of Patent: November 4, 1986Assignee: TDK CorporationInventors: Masao Shigeta, Shotatsu Sugenoya, Tsutomu Cho
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Patent number: 4603314Abstract: The improved structure of an inductor with an amorphous sheet core and a winding has been found. A core assembly has a pair of housing halves made of non-magnetic material with U-shaped track, in which a laminated amorphous sheet is mounted. The ends of the halves are inserted in a winding so that the ends of the cores abut with each other directly or through a gap spacer. The core halves are pressed by spring action to assemble the inductor. The core halves are produced by the steps of winding an amorphous sheet to a coil, inserting the coil in the track of the housing, and impregnating the coil with plastics.Type: GrantFiled: October 18, 1983Date of Patent: July 29, 1986Assignee: TDK CorporationInventors: Kazuo Fukunaga, Minoru Higurashi, Motoyoshi Fujita, Eiichi Suga, Masao Shigeta, Norio Sato
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Patent number: 4587507Abstract: Conventionally, silicon steel strips and ferrite cores have been used as the core of a choke coil. These strips and the like have not yet been replaced with amorphous alloy because in the known amorphous magnetic alloy the pre-magnetization characteristic, the amount of heat generated, and the secular change are poor.The present invention proposes a core of a choke coil which consists of a coiled thin strip of an amorphous alloy, and has at least one cut air gap, the coiled regions of the thin strip being bound to one another at at least in the neighborhood of said at least one cut air gap, and said amorphous magnetic alloy is essentially comprised of the following composition, Fe.sub.x Mn.sub.y (Si.sub.p B.sub.q P.sub.r C.sub.s).sub.z, wherein x+y+z is 100 atomic % based on all of the elements, y is from 0.001 to 10 atomic %, z is from 21 to 25.5 atomic %, p+q+r+s is atomic % 1, p is from 0.40 to 0.75, r is fro 0.0001 to 0.05, the ratio s/q is from 0.03 to 0.4, and z is z.ltoreq.50p+1, z.ltoreq.10p+19, z.Type: GrantFiled: November 23, 1982Date of Patent: May 6, 1986Assignee: TDK Electronics Co., Ltd.Inventors: Suguru Takayama, Masao Shigeta
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Patent number: 4558297Abstract: The present invention relates to a saturable core which consists of a coiled thin strip of an amorphous magnetic alloy. The present invention provides a saturable core having a high .DELTA.Bs, a low power loss, a good saturation property, and low secular changes of the magnetic properties, due to determining the coiling direction of the saturable core so that it is the same as that of a coil heat treated.Type: GrantFiled: October 4, 1983Date of Patent: December 10, 1985Assignee: TDK CorporationInventors: Masao Shigeta, Teruhiko Ojima