Patents by Inventor Taeko Tsubokura
Taeko Tsubokura 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: 9997284Abstract: A sintered magnet of a preferred embodiment has a composition comprising: R (R is a rare earth element that must contain any one of Nd and Pr.): 29.5 to 33.0 mass %; B: 0.7 to 0.95 mass %; Al: 0.03 to 0.6 mass %; Cu: 0.01 to 1.5 mass %; Co: 3.0 mass % or less (provided that 0 mass % is not included.); Ga: 0.1 to 1.0 mass %; C: 0.05 to 0.3 mass %; O: 0.03 to 0.4 mass %; and Fe and other elements: a balance, and wherein a content of heavy rare earth elements in total is 1.0 mass % or less, and wherein the following relations are satisfied: 0.29<[B]/([Nd]+[Pr])<0.40 and 0.07<([Ga]+[C])/[B]<0.60, where [Nd], [Pr], [B], [C] and [Ga] represent the numbers of atoms of Nd, Pr, B, C and Ga, respectively.Type: GrantFiled: June 21, 2013Date of Patent: June 12, 2018Assignee: TDK CORPORATIONInventors: Masashi Miwa, Atsushi Fujiwara, Eiji Kato, Taeko Tsubokura, Koji Mitake, Chikara Ishizaka
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Patent number: 9620268Abstract: An R-T-B based alloy strip including columnar crystals of an R2T14B phase, wherein in a cross-section along the thickness direction, columnar crystals extend out in a radial fashion from the crystal nuclei, the R-T-B based alloy strip satisfying the following inequality (1), where D1 and D2 are, respectively, the average value for the lengths of the columnar crystals on one side and the average value for the lengths on the other side that is opposite the one side, in the direction perpendicular to the thickness direction of the cross-section. 0.9/1.1?D2/D1?1.1/0.Type: GrantFiled: October 11, 2012Date of Patent: April 11, 2017Assignee: TDK CORPORATIONInventors: Taeko Tsubokura, Eiji Kato, Tamotsu Ishiyama, Nobuhiro Jingu, Chikara Ishizaka
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Patent number: 9613737Abstract: An R-T-B sintered magnet including a composition containing a rare earth element, a transition element and boron, containing essentially no dysprosium as a rare earth element, and having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the triple point regions which are grain boundary regions surrounded by 3 or more crystal grains have a composition containing a rare earth element, a transition element and boron and have a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 ?m2 and the standard deviation of the area distribution being no greater than 3.Type: GrantFiled: October 11, 2012Date of Patent: April 4, 2017Assignee: TDK CORPORATIONInventors: Eiji Kato, Chikara Ishizaka, Taeko Tsubokura, Tamotsu Ishiyama, Nobuhiro Jingu
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Patent number: 9607742Abstract: An R-T-B based alloy strip containing dendritic crystals including a R2T14B phase, wherein on at least one surface, the average value for the widths of the dendritic crystals is no greater than 60 ?m, and the number of crystal nuclei in the dendritic crystals is at least 500 per 1 mm square area.Type: GrantFiled: October 11, 2012Date of Patent: March 28, 2017Assignee: TDK CORPORATIONInventors: Tamotsu Ishiyama, Taeko Tsubokura, Eiji Kato, Nobuhiro Jingu, Chikara Ishizaka
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Patent number: 9548149Abstract: The present invention provides a rare earth based magnet having a microstructure in which in a section of the R2T14B main-phase crystal grains, the number density of the fine products in the interior of (inside) the crystal grains is larger than that in the periphery of (outside) the crystal grains. That is, the rare earth based magnet includes R2T14B main-phase crystal grains and grain boundary phases formed between the R2T14B main-phase crystal grains. The R2T14B main-phase crystal grains include a substance where fine products are formed in the crystal grains. In the section of the main-phase crystal grains, when the crystal grains are divided into the interior of the crystal grains and the periphery of the crystal grains with a specific ellipse, the fine products are formed such that the number density in the interior is larger than that in the periphery.Type: GrantFiled: March 28, 2014Date of Patent: January 17, 2017Assignee: TDK CORPORATIONInventors: Eiji Kato, Yoshinori Fujikawa, Taeko Tsubokura, Chikara Ishizaka, Katsuo Sato
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Publication number: 20150310972Abstract: The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like than before are used. The rare earth based magnet according to the present invention is a sintered magnet which includes R2T14B crystal grains as main phase and grain boundary phases between the R2T14B crystal grains. when evaluating the cross-sectional area distribution of the main phase crystal grains by histogram in any cross-section of the rare earth based magnet, the crystal grains with large particle size and the crystal grains with small particle size are controlled so that the cross-sectional area distribution becomes the one which respectively has at least one peak at two sides of the average value of the cross-sectional area.Type: ApplicationFiled: July 16, 2014Publication date: October 29, 2015Inventors: Eiji KATO, Yoshinori FUJIKAWA, Taeko TSUBOKURA, Chikara ISHIZAKA, Katsuo SATO
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Publication number: 20150270041Abstract: The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like than before are used. The rare earth based magnet according to the present invention is a sintered magnet which includes R2T14B crystal grains as main phase and grain boundary phases between the R2T14B crystal grains. When the grain boundary phase surrounded by three or more main phase crystal grains is regarded as the grain boundary multi-point, the microstructure of the sintered body is controlled so that the ratio of the grain boundary triple-point surrounded by three main phase crystal grains in all grain boundary multi-points to be specified value or less.Type: ApplicationFiled: July 16, 2014Publication date: September 24, 2015Inventors: Eiji KATO, Yoshinori FUJIKAWA, Taeko TSUBOKURA, Chikara ISHIZAKA, Katsuo SATO
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Publication number: 20150170810Abstract: A sintered magnet of a preferred embodiment has a composition comprising: R (R is a rare earth element that must contain any one of Nd and Pr.): 29.5 to 33.0 mass %; B: 0.7 to 0.95 mass %; Al: 0.03 to 0.6 mass %; Cu: 0.01 to 1.5 mass %; Co: 3.0 mass % or less (provided that 0 mass % is not included.); Ga: 0.1 to 1.0 mass %; C: 0.05 to 0.3 mass %; O: 0.03 to 0.4 mass %; and Fe and other elements: a balance, and wherein a content of heavy rare earth elements in total is 1.0 mass % or less, and wherein the following relations are satisfied: 0.29<[B]/([Nd]+[Pr])<0.40 and 0.07<([Ga]+[C])/[B]<0.60, where [Nd], [Pr], [B], [C] and [Ga] represent the numbers of atoms of Nd, Pr, B, C and Ga, respectively.Type: ApplicationFiled: June 21, 2013Publication date: June 18, 2015Inventors: Masashi Miwa, Atsushi Fujiwara, Eiji Kato, Taeko Tsubokura, Koji Mitake, Chikara Ishizaka
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Publication number: 20140308152Abstract: An R-T-B based alloy strip including columnar crystals of an R2T14B phase, wherein in a cross-section along the thickness direction, columnar crystals extend out in a radial fashion from the crystal nuclei, the R-T-B based alloy strip satisfying the following inequality (1), where D1 and D2 are, respectively, the average value for the lengths of the columnar crystals on one side and the average value for the lengths on the other side that is opposite the one side, in the direction perpendicular to the thickness direction of the cross-section. 0.9/1.1?D2/D1?1.1/0.Type: ApplicationFiled: October 11, 2012Publication date: October 16, 2014Inventors: Taeko Tsubokura, Eiji Kato, Tamotsu Ishiyama, Nobuhiro Jingu, Chikara Ishizaka
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Publication number: 20140292454Abstract: The present invention provides a rare earth based magnet having a microstructure in which in a section of the R2T14B main-phase crystal grains, the number density of the fine products in the interior of (inside) the crystal grains is larger than that in the periphery of (outside) the crystal grains. That is, the rare earth based magnet includes R2T14B main-phase crystal grains and grain boundary phases formed between the R2T14B main-phase crystal grains. The R2T14B main-phase crystal grains include a substance where fine products are formed in the crystal grains. In the section of the main-phase crystal grains, when the crystal grains are divided into the interior of the crystal grains and the periphery of the crystal grains with a specific ellipse, the fine products are formed such that the number density in the interior is larger than that in the periphery.Type: ApplicationFiled: March 28, 2014Publication date: October 2, 2014Inventors: Eiji KATO, Yoshinori FUJIKAWA, Taeko TSUBOKURA, Chikara ISHIZAKA, Katsuo SATO
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Publication number: 20140290803Abstract: The present invention provides a rare earth based magnet including R2T14B main-phase crystal grains, and two-grain boundary phases between adjacent two R2T14B main-phase crystal grains, the two-grain boundary phases are controlled such that the thickness thereof is 5 nm or more and 500 nm or less, and it is composed of a phase with a magnetism different from that of a ferromagnet.Type: ApplicationFiled: March 28, 2014Publication date: October 2, 2014Inventors: Eiji KATO, Yoshinori FUJIKAWA, Taeko TSUBOKURA, Chikara ISHIZAKA, Katsuo SATO
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Publication number: 20140292453Abstract: The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like are used. The rare earth based magnet according to the present invention includes R2T14B main phase crystal grains and grain boundary phases between adjacent main phase crystal grains. In any cross-section of the rare earth based magnet, when evaluating the circular degree of the main phase crystal grains with Wadell's Roundenss A, the shape of the main phase crystal grains is controlled such that the Roundness A becomes 0.24 or more.Type: ApplicationFiled: March 28, 2014Publication date: October 2, 2014Inventors: Eiji KATO, Yoshinori FUJIKAWA, Taeko TSUBOKURA, Chikara ISHIZAKA, Katsuo SATO
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Publication number: 20140286816Abstract: An R-T-B sintered magnet including a composition containing a rare earth element, a transition element and boron, containing essentially no dysprosium as a rare earth element, and having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the triple point regions which are grain boundary regions surrounded by 3 or more crystal grains have a composition containing a rare earth element, a transition element and boron and have a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 ?m2 and the standard deviation of the area distribution being no greater than 3.Type: ApplicationFiled: October 11, 2012Publication date: September 25, 2014Applicant: TDK CORPORATIONInventors: Eiji Kato, Chikara Ishizaka, Taeko Tsubokura, Tamotsu Ishiyama, Nobuhiro Jingu
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Publication number: 20140286815Abstract: An R-T-B based alloy strip containing dendritic crystals including a R2T14B phase, wherein on at least one surface, the average value for the widths of the dendritic crystals is no greater than 60 ?m, and the number of crystal nuclei in the dendritic crystals is at least 500 per 1 mm square area.Type: ApplicationFiled: October 11, 2012Publication date: September 25, 2014Applicant: TDK CORPORATIONInventors: Tamotsu Ishiyama, Taeko Tsubokura, Eiji Kato, Nobuhiro Jingu, Chikara Ishizaka
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Publication number: 20140247100Abstract: An R-T-B sintered magnet 100 including particles containing an R2T14B phase, obtained using an R-T-B alloy strip containing crystal grains of an R2T14B phase, wherein the R-T-B alloy strip has, in a cross-section along the thickness direction, the crystal grains extending in a radial fashion from the crystal nuclei, the following inequality (1) being satisfied, where the average value of the lengths of the crystal grains on one side in the direction perpendicular to the thickness direction and the average value of the lengths on the other side opposite the one side are represented as D1 and D2, respectively, the mean particle diameter of the particles is 0.5 to 5 ?m, and essentially no heavy rare earth elements are present. 0.9?D2/D1?1.Type: ApplicationFiled: October 11, 2012Publication date: September 4, 2014Applicant: TDK CORPORATIONInventors: Taeko Tsubokura, Chikara Ishizaka, Eiji Kato, Tamotsu Ishiyama, Nobuhiro Jingu
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Patent number: 8152936Abstract: There is provided a rare earth magnet with excellent Br and HcJ values. The rare earth magnet according to a preferred embodiment of the invention is characterized by being composed mainly of R (where R is at least one element selected from among rare earth elements including Y), B, Al, Cu, Zr, Co, O, C and Fe, wherein the content of each element is R: 25-34 wt %, B: 0.85-0.98 wt %, Al: 0.03-0.3 wt %, Cu: 0.01-0.15 wt %, Zr: 0.03-0.25 wt %, Co: ?3 wt % (but not 0 wt %), O: ?0.2 wt %, C: 0.03-0.15 wt % and Fe: remainder.Type: GrantFiled: June 27, 2008Date of Patent: April 10, 2012Assignee: TDK CorporationInventors: Taeko Tsubokura, Makoto Iwasaki, Makoto Nakane, Fumitaka Baba
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Publication number: 20100233016Abstract: There is provided a rare earth magnet with excellent Br and HcJ values. The rare earth magnet according to a preferred embodiment of the invention is characterized by being composed mainly of R (where R is at least one element selected from among rare earth elements including Y), B, Al, Cu, Zr, Co, O, C and Fe, wherein the content of each element is R: 25-34 wt %, B: 0.85-0.98 wt %, Al: 0.03-0.3 wt %, Cu: 0.01-0.15 wt %, Zr: 0.03-0.25 wt %, Co: ?3 wt % (but not 0 wt %), O: ?0.2 wt %, C: 0.03-0.15 wt % and Fe: remainder.Type: ApplicationFiled: June 27, 2008Publication date: September 16, 2010Applicant: TDK CorporationInventors: Taeko Tsubokura, Makoto Iwasaki, Makoto Nakane, Fumitaka Baba
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Publication number: 20040046152Abstract: The present invention provides a method for manufacturing a permanent magnet based on oxide magnetic material, comprising a binder addition step for adding a binder to raw material powder containing oxide magnetic materials for mixing; a water content adjustment step for adjusting the water content of a molding mixture containing the raw material powder and the binder; an in-magnetic-field dry molding step for loading the molding mixture with adjusted water content into a mold and pressing it in a magnetic field applied while aligning the directions of easy magnetization of oxide magnetic material powder particles; and a sintering step for sintering the molded body; wherein the binder in the binder addition step is a wax based on fatty acid ester, and wherein the molding mixture charged into the mold in the in-magnetic-field dry molding step contains aggregates, in which the percentage of existence of aggregates in size of 500 &mgr;m or more is 0.01 to 0.Type: ApplicationFiled: June 23, 2003Publication date: March 11, 2004Inventors: Taeko Tsubokura, Tsuneo Suzuki, Takahiro Mori, Taku Murase
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Patent number: 6391814Abstract: A piezoelectric ceramic having a carbon content after sintering of less than 37 ppm by weight and a piezoelectric device such as a ceramic resonator, ceramic filter, piezoelectric element, piezoelectric buzzer, piezoelectric transformer, and ultrasonic vibrator using the same.Type: GrantFiled: June 14, 2000Date of Patent: May 21, 2002Assignee: TDK CorporationInventors: Taeko Tsubokura, Takeo Tsukada, Takeshi Nomura
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Patent number: 6090306Abstract: Provided is a piezoelectric ceramic which achieves a high density, good temperature characteristics and a high Curie temperature, which can fully prevent (a) a decrease in Qmax (Qmax refers to a tan.theta.max when the maximum value of phase angles of third harmonic is a .theta.max), (b) a decrease in q (dynamic range of resonance frequency), (c) an increase in a fundamental wave and (d) the occurrence of a spurious mode in the vicinity of third harmonic, caused by downsizing, and which can materialize a small-sized high-performance piezoelectric element, the piezoelectric ceramic having a composition of the general formula,(Pb.sub.a-k-y-z Sr.sub.x Ln.sub.y Bi.sub.z)(Ti.sub.1-b-c Mn.sub.b Me.sub.c)O.sub.3wherein Ln is at least one element selected from the group consisting of La, Ce and Pr, Me is at least one element selected from the group consisting of Nb, Sb and Ta, and x, y, z, a, b and c represent molar ratios, the composition satisfying 0.ltoreq.x.ltoreq.0.2, 0<y.ltoreq.0.1, 0.001.ltoreq.z.ltoreq.0.Type: GrantFiled: February 11, 1999Date of Patent: July 18, 2000Assignee: TDK CorporationInventors: Taeko Tsubokura, Hitoshi Oka, Kazuo Miyabe, Masayoshi Inoue