Patents by Inventor Tomofumi Kuroda
Tomofumi Kuroda 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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Publication number: 20150213941Abstract: A reactor using a composite magnetic core in which a ferrite core and a soft magnetic metal core are combined. The reactor is composed of a pair of yoke portion magnetic portions composed of a ferrite core, winding portion core(s) disposed between the opposite planes of the yoke portion cores, and coil(s) wound around the winding portion core(s). The winding portion core(s) is/are made of a soft magnetic metal core, and the cross sectional area of the part for winding the coil of the winding portion core is substantially constant. When the cross sectional area of the part for winding the coil of the winding portion core is set as S1, and the area of the parts opposite to the yoke portion cores in the winding portion core(s) is set as S2, the area ratio S2/S1 is set to be 1.3 to 4.0.Type: ApplicationFiled: January 22, 2015Publication date: July 30, 2015Inventors: Tomofumi KURODA, Yu SAKURAI, Hideyuki ITOH
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Publication number: 20150213944Abstract: A reactor uses a composite magnetic core which combines a ferrite core and a soft magnetic metal core. The reactor is composed of a pair of yoke portion cores composed of ferrite cores, winding portion core(s) disposed between the opposite planes of the yoke portion cores, and coil(s) wound around the winding portion core(s). Flange-like members are disposed at the end part of the winding portion core(s) in a way of being external connected with the periphery of winding portion core(s) which is composed of a soft magnetic metal core. The flange-like member is composed of a metal material with iron as the main component which can be magnetically attracted to a magnet, and a junction portion of the flange-like member and the yoke portion core is formed at one flat plane of the member which is the same plane with an end plane of the winding portion core.Type: ApplicationFiled: January 23, 2015Publication date: July 30, 2015Inventors: Tomofumi KURODA, Yu SAKURAI
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Publication number: 20120229354Abstract: A magnetic material for antennas including: an M-type hexagonal ferrite represented by the following general formula (1) as a main phase, MA.Fe12-x.MBx.O19 (wherein MA is at least one kind selected from the group consisting of Sr and Ba, MB is MC or MD, MC is at least one kind selected from the group consisting of Al, Cr, Sc and In, MD is an equivalent mixture of at least one kind selected from the group consisting of Ti, Sn and Zr and at least one kind selected from the group consisting of Ni, Zn, Mn, Mg, Cu and Co, X is a number from 1 to 5), and an average crystal particle diameter is equal to or greater than 5 ?m.Type: ApplicationFiled: January 17, 2012Publication date: September 13, 2012Applicant: TDK CORPORATIONInventors: Tomokazu ISHIKURA, Michihiro MURAMOTO, Akihiro HARADA, Katsumi KAWASAKI, Tomofumi KURODA
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Patent number: 8252124Abstract: The present invention provides a powder magnetic core low in the loss and high in the saturation magnetic flux density and a method for manufacturing the same. More specifically, the present invention provides a powder magnetic core that comprises a soft magnetic metal powder having an average particle size (D50) of 0.5 to 5 ?m, a half width of diffraction peak in a <110> direction of ?-Fe as measured by X-ray powder diffraction of 0.2 to 5.0°, and an Fe content of 97.0% by mass or more, the core having an oxygen content of 2.0% by mass or more.Type: GrantFiled: March 11, 2011Date of Patent: August 28, 2012Assignee: TDK CorporationInventors: Masahito Koeda, Tomofumi Kuroda, Tomokazu Ishikura, Akihiro Harada, Hiroyuki Ono, Osamu Kido, Satoko Ueda
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Publication number: 20110227679Abstract: The present invention provides a powder magnetic core low in the loss and high in the saturation magnetic flux density and a method for manufacturing the same. More specifically, the present invention provides a powder magnetic core that comprises a soft magnetic metal powder having an average particle size (D50) of 0.5 to 5 ?m, a half width of diffraction peak in a <110> direction of ?-Fe as measured by X-ray powder diffraction of 0.2 to 5.0°, and an Fe content of 97.0% by mass or more, the core having an oxygen content of 2.0% by mass or more.Type: ApplicationFiled: March 11, 2011Publication date: September 22, 2011Applicant: TDK CORPORATIONInventors: Masahito KOEDA, Tomofumi KURODA, Tomokazu ISHIKURA, Akihiro HARADA, Hiroyuki ONO, Osamu KIDO, Satoko UEDA
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Publication number: 20110101262Abstract: The invention provides surface-treated reduced iron powder from which a powder magnetic core can be produced so that the powder magnetic core has small core loss and small frequency-dependence of the core loss and exhibits small core loss even when driven at high frequencies of 1 MHz or more. The surface-treated reduced iron powder is obtained by at least surface-treating reduced iron powder prepared by a reduction and slow oxidation method, and contains secondary particles formed through agglomeration of primary particles, the primary particles having an average particle diameter of 0.01-5 ?m. The secondary particles have a D90% particle diameter of 20 ?m or less, the surface of the primary particles is at least in part coated with an insulating layer containing iron phosphate, and the phosphorus content is 500-10000 ppm.Type: ApplicationFiled: October 1, 2010Publication date: May 5, 2011Applicant: TDK CORPORATIONInventors: Tomofumi KURODA, Masahito KOEDA
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Patent number: 7713465Abstract: Provided is a process for producing a MnZn-base ferrite comprising: firing a compacted raw material to produce the MnZn-base ferrite, wherein the firing comprises, in the following order: a heating phase comprising gradually bringing a firing temperature from room temperature up to a maximum temperature; a maximum temperature holding phase comprising maintaining the maximum temperature for a period of time, wherein a partial pressure of oxygen (p2) at the maximum temperature holding phase is greater than an equilibrium partial pressure of oxygen (p1) as follows: p2>p1, wherein the equilibrium partial pressure of oxygen (p1) is represented by the following equation: log(p1)=log(PO2)=a?b/T, wherein PO2 is measured in a unit of %, and T is measured in a unit of absolute temperature K; and a cooling phase comprising gradually bringing the maximum temperature down to near room temperature, wherein a partial pressure of oxygen (p3) at the cooling phase is operated at an equilibrium partial pressure of oxygen basType: GrantFiled: March 21, 2008Date of Patent: May 11, 2010Assignee: TDK CorporationInventors: Shenglei Che, Kentaro Mori, Masahiko Watanabe, Takuya Aoki, Tomofumi Kuroda
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Publication number: 20080236706Abstract: Firing is carried out such that for operation of a partial pressure of oxygen and temperature at the high-temperature holding operation phase and cooling operation phase, the following equilibrium relation equation (1) indicative of an equilibrium relation of a partial pressure of oxygen (PO2 in %) to a temperature (T in absolute temperature K) is used to set the values of a and b at given values of a=a* and b=b*, respectively, Log(PO2)=a?b/T ??Eq.Type: ApplicationFiled: March 21, 2008Publication date: October 2, 2008Applicant: TDK CORPORATIONInventors: Shenglei CHE, Kentaro MORI, Masahiko WATANABE, Takuya AOKI, Tomofumi KURODA
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Publication number: 20070181847Abstract: It is an object to provide a ferrite material which has a higher saturation magnetic flux density and low core loss, both at 100° C. The ferrite material is composed of a sintered body containing Fe, Mn and Zn as main constituents at x, y and z % by mol in terms of Fe2O3, MnO and ZnO, respectively, and containing Li as an additive at v % by weight in terms of Li2CO3 based on the main constituents, wherein x=55.7 to 60, z=3 to 8.5, y=100?x?z, v=0.3 to 0.8, and x1?x?x2 (x1=52.9?0.1z+8.5v and x2=54.4?0.1z+8.5v).Type: ApplicationFiled: February 6, 2007Publication date: August 9, 2007Applicant: TDK CORPORATIONInventors: Tomofumi Kuroda, Isao Nakahata, Masahiko Watanabe, Masahito Furukawa, Osamu Hasegawa, Takuya Aoki
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Publication number: 20070152183Abstract: There is provided a piezoelectric ceramic having a wider operating temperature range, being capable of obtaining a larger amount of displacement, being easily sintered, and being superior in terms of low emission, environment and ecology. A piezoelectric substrate (1) includes (1?m?n){(Na1-x-yKxLiy)(Nb1-zTaz)O3}+m{(M1)ZrO3}+n{M2(Nb1-wTaw)2O6} as a main component. M1 and M2 each represent an alkaline-earth metal element, and the values of x, y, m and n are preferably within a range of 0.1?x?0.9, 0?y?0.1, 0<m<0.1 and 0<n?0.01, respectively. Thereby, a higher Curie temperature and a larger amount of displacement can be obtained, and sintering can be more easily performed. At the time of sintering, after (M1) ZrO3 is formed, other materials are mixed.Type: ApplicationFiled: December 21, 2004Publication date: July 5, 2007Applicant: TDK CORPORATIONInventors: Masahito Furukawa, Masaru Nanao, Shougo Murosawa, Naoyoshi Satou, Tomofumi Kuroda
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Patent number: 6402979Abstract: There is disclosed a magnetic ferrite material obtained by calcining a raw material, forming a calcined powder into a desired shape and sintering to contain Fe2O3, MnO and ZnO as main components, the magnetic ferrite material with a low power loss is realized by setting the coefficient of variation (CV value) of the content of a Ca component precipitated along a grain boundary in a range of 1 to 60%, and the magnetic ferrite material is manufactured by calcining the raw material containing Fe2O3, MnO and ZnO as the main components to obtain the calcined powder in which that the S component content is in a range of 1 to 200 ppm, and forming the calcined powder into the desired shape and sintering.Type: GrantFiled: July 28, 2000Date of Patent: June 11, 2002Assignee: TDK CorporationInventors: Hitoshi Saita, Tomofumi Kuroda, Naoyoshi Sato
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Patent number: 6077453Abstract: Provided are an Mn--Zn ferrite in which the core loss is low and Bs is high at high temperatures; a transformer capable of being small-sized and suitable to use at high temperatures; and a method for efficiently driving the transformer. Also provided is a transformer capable of being small-sized and suitable to use in a broad temperature range including high temperatures. Further provided are a high-efficiency transformer capable of being small-sized, in which the core loss in the ferrite core is low and the saturation magnetic flux density is high therein at the temperature at which the transformer is driven; and a high-efficiency driving method for the transformer. Depending on its use, Mn--Zn ferrite to be the ferrite core for the transformers comprises, as the essential components, specific amounts of Fe.sub.2 O.sub.3, ZnO and MnO, and, as the side components, specific amounts of SiO.sub.2, CaCO.sub.3, Nb.sub.2 O.sub.5 and ZrO.sub.2. The core of the transformers is made of the Mn--Zn ferrite.Type: GrantFiled: January 15, 1999Date of Patent: June 20, 2000Assignee: TDK CorporationInventors: Hitoshi Saita, Tomofumi Kuroda, Shigeo Okamoto, Naoyoshi Sato