Patents by Inventor Ritsu Tanaka

Ritsu Tanaka 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: 8541102
    Abstract: Piezoelectric materials having improved electrical properties, and manufacturing methods of the same, are provided. In (Li, Na, K, Bi)(Nb, Ta)O3 based piezoelectric materials, the surface microstructures of sintered bodies include microscopic grains having grain diameters of less than 5 ?m, intermediate grains having grain diameters of 5 ?m or more and less than 15 ?m, and coarse grains having grain diameters of 15 ?m or more and 100 ?m or less.
    Type: Grant
    Filed: July 1, 2009
    Date of Patent: September 24, 2013
    Assignee: NGK Insulators, Ltd.
    Inventors: Kazuyuki Kaigawa, Ritsu Tanaka, Hirofumi Yamaguchi
  • Patent number: 8414791
    Abstract: A piezoelectric/electrostrictive ceramic sintered body has a microstructure in which a matrix phase and an additional material phase having different compositions coexist and the additional material phase is dispersed in the matrix phase. A residual strain ratio of the additional material phase alone is larger than a residual strain ratio of the matrix phase alone. The matrix phase and the additional material phase have a composition in which a Mn compound containing Mn atoms of 0 parts by mole or more and 3 parts by mole or less and a Ba compound containing Ba atoms of 0 parts by mole or more and 1 part by mole or less are contained in a composite of 100 parts by mole represented by a general formula {Liy(Na1-xKx)1-y}a(Nb1-z-wTazSbw)O3, where a, x, y, z and w satisfy 0.9?a?1.2, 0.2?x?0.8, 0.0?y?0.2, 0?z?0.5 and 0?w?0.1, respectively.
    Type: Grant
    Filed: December 13, 2010
    Date of Patent: April 9, 2013
    Assignee: NGK Insulators, Ltd.
    Inventors: Kazuyuki Kaigawa, Ritsu Tanaka
  • Patent number: 8277680
    Abstract: A (Li, Na, K)(Nb, Ta)O3-based piezoelectric/electrostrictive ceramic composition having large electric field-induced distortion at the time of application of a high electric field is provided. A perovskite oxide is synthesized which contains Li (lithium), Na (sodium) and K (potassium) as A-site elements and contains at least Nb (niobium) and Sb (antimony) out of Nb, Ta (tantalum) and Sb as B-site elements, the ratio of the total number of atoms of the A-site elements to the total number of atoms of the B-site elements being larger than 1, and then a Bi (bismuth) compound is added and reacted. The amount of addition of the Bi compound with respect to 100 molar parts of the perovskite oxide is preferably not less than 0.02 molar part nor more than 0.1 molar part in terms of Bi atoms.
    Type: Grant
    Filed: July 22, 2009
    Date of Patent: October 2, 2012
    Assignee: NGK Insulators, Ltd.
    Inventors: Ritsu Tanaka, Hirofumi Yamaguchi
  • Patent number: 8193687
    Abstract: An alkali niobate-based piezoelectric/electrostrictive ceramics sintered body including, as a main crystal phase, a perovskite type oxide containing at least one type of element selected from the group consisting of Li, Na and K as A site constituent elements and at least one type of element selected from the group consisting of Nb and Ta as B site constituent elements. The number of lattice-strained layers of the piezoelectric/electrostrictive ceramics sintered body is preferably small. A diffuse scattering intensity ratio, which is a ratio of an intensity of diffuse scattering by a lattice-strained layer present near a domain wall to a sum of an X-ray diffraction intensity of a first lattice plane and that of a second lattice plane different in interplanar spacing from the first lattice plane due to crystallographic symmetry reduction is preferably 0.5 or lower.
    Type: Grant
    Filed: July 24, 2009
    Date of Patent: June 5, 2012
    Assignee: NGK Insulators, Ltd.
    Inventors: Kazuyuki Kaigawa, Ritsu Tanaka, Hirofumi Yamaguchi
  • Patent number: 8128834
    Abstract: A (Li, Na, K)(Nb, Ta)O3 based piezoelectric/electrostrictive porcelain composition obtained by adding a slight amount of a Mn compound to a perovskite type oxide containing Li, Na and K as A-site elements and contains at least Nb out of Nb and Ta as B-site elements, where a ratio of a total number of atoms of the A-site elements to a total number of atoms of the B-site elements is not smaller than 1. A composition of the perovskite type oxide as a principal component is represented by a general formula: {Liy(Na1-xKx)1-y}a(Nb1-zTaz)O3. The A/B ratio “a” preferably satisfies 1<a?1.05. The Mn compound as an accessory component is desirably added such that the added amount is not more than 3 parts by mol in terms of Mn atom with respect to 100 parts by mol of said perovskite type oxide.
    Type: Grant
    Filed: February 25, 2008
    Date of Patent: March 6, 2012
    Assignee: NGK Insulators, Ltd.
    Inventors: Yukinobu Yura, Hirofumi Yamaguchi, Ritsu Tanaka
  • Patent number: 8119023
    Abstract: A (Li, Na, K)(Nb, Ta)O3-based piezoelectric/electrostrictive ceramic composition having a large field-induced distortion during application of a high electric field is provided. After synthesizing a perovskite oxide containing Li (lithium), Na (sodium) and K (potassium) as A-site elements and containing at least Nb (niobium) out of the Nb and Ta (tantalum) as B-site elements, a ratio of total number of atoms of the A-site elements to total number of atoms of the B-site elements being higher than 1, a Bi (bismuth) compound is added to the perovskite oxide and the perovskite oxide is reacted with the Bi compound. An addition amount of the Bi compound with respect to 100 molar parts of the perovskite oxide is preferably equal to or greater than 0.01 molar part and equal to or smaller than 0.1 molar part in terms of Bi atoms.
    Type: Grant
    Filed: March 6, 2009
    Date of Patent: February 21, 2012
    Assignee: NGK Insulators, Ltd.
    Inventors: Ritsu Tanaka, Hirofumi Yamaguchi, Yukinobu Yura
  • Patent number: 8034249
    Abstract: A piezoelectric/electrostrictive ceramic sintered body has a microstructure in which a matrix phase and an additional material phase having different compositions coexist and the additional material phase is dispersed in the matrix phase. A residual strain ratio of the additional material phase alone is larger than a residual strain ratio of the matrix phase alone. The matrix phase and the additional material phase have a composition in which a Mn compound containing Mn atoms of 0 parts by mol or more and 3 parts by mol or less and a Sr compound containing Sr atoms of 0 parts by mol or more and 1 part by mol or less are contained in a composite of 100 parts by mol represented by a general formula {Liy(Na1-xKx)1-y}a(Nb1-z-wTazSbw)O3, where a, x, y, z and w satisfy 0.9?a?1.2, 0.2?x?0.8, 0.0?y?0.2, 0?z?0.5 and 0?w?0.1, respectively.
    Type: Grant
    Filed: July 6, 2010
    Date of Patent: October 11, 2011
    Assignee: NGK Insulators, Ltd.
    Inventors: Kazuyuki Kaigawa, Ritsu Tanaka
  • Publication number: 20110234044
    Abstract: Provided is a piezoelectric/electrostrictive ceramic which produces large electric-field induced strain without performing an aging treatment for a long period of time. A piezoelectric/electrostrictive ceramic sintered body in which the ratio of the number of ions at A sites to the number of ions at B sites in a perovskite structure is at least 0.94 to at most 0.99 is subjected to an oxygen heat treatment at a temperature of 600 to 1050° C. for 2 to 100 hours under an atmosphere with an oxygen partial pressure of 0.05 to 1.0 atm.
    Type: Application
    Filed: November 22, 2010
    Publication date: September 29, 2011
    Applicants: NGK Insulators, Ltd., The University of Tokyo
    Inventors: Yuji NOGUCHI, Masaru MIYAYAMA, Toshikatsu KASHIWAYA, Takaaki KOIZUMI, Shuichi OZAWA, Ritsu TANAKA
  • Publication number: 20110210281
    Abstract: A piezoelectric/electrostrictive ceramic sintered body has a microstructure in which a matrix phase and an additional material phase having different compositions coexist and the additional material phase is dispersed in the matrix phase. A residual strain ratio of the additional material phase alone is larger than a residual strain ratio of the matrix phase alone. The matrix phase and the additional material phase have a composition in which a Mn compound containing Mn atoms of 0 parts by mole or more and 3 parts by mole or less and a Ba compound containing Ba atoms of 0 parts by mole or more and 1 part by mole or less are contained in a composite of 100 parts by mole represented by a general formula {Liy(Na1-xKx)1-y}a(Nb1-z-wTazSbw)O3, where a, x, y, z and w satisfy 0.9?a?1.2, 0.2?x?0.8, 0.0?y?0.2, 0?z?0.5 and 0?w?0.1, respectively.
    Type: Application
    Filed: December 13, 2010
    Publication date: September 1, 2011
    Applicant: NGK Insulators, Ltd.
    Inventors: Kazuyuki KAIGAWA, Ritsu Tanaka
  • Publication number: 20110012051
    Abstract: To provide an alkaline-niobate-based piezoelectric/electrostrictive ceramic composition that has excellent electric field induced strain during application of high electric field. A piezoelectric/electrostrictive film is a sintered body of a piezoelectric/electrostrictive ceramic composition. The piezoelectric/electrostrictive ceramic composition is a piezoelectric/electrostrictive composition, in which a compound of at least one kind of element selected from the group consisting of Ba, Sr, Ca, La, Ce, Nd, Sm, Dy, Ho and Yb and a Mn compound are contained in a perovskite-type oxide containing Li, Na and K as A-site elements and Nb and Sb as B-site elements, where a ratio of a total number of atoms of the A-site elements to a total number of atoms of the B-site elements is more than one and the number of atoms of Sb to the total number of atoms of the B-site elements is 1 mol % or more and 10 mol % or less.
    Type: Application
    Filed: July 8, 2010
    Publication date: January 20, 2011
    Applicant: NGK Insulators, Ltd.
    Inventors: Kazuyuki KAIGAWA, Ritsu TANAKA
  • Publication number: 20110006244
    Abstract: A piezoelectric/electrostrictive ceramic sintered body has a microstructure in which a matrix phase and an additional material phase having different compositions coexist and the additional material phase is dispersed in the matrix phase. A residual strain ratio of the additional material phase alone is larger than a residual strain ratio of the matrix phase alone. The matrix phase and the additional material phase have a composition in which a Mn compound containing Mn atoms of 0 parts by mol or more and 3 parts by mol or less and a Sr compound containing Sr atoms of 0 parts by mol or more and 1 part by mol or less are contained in a composite of 100 parts by mol represented by a general formula {Liy(Na1-xKx)1-y}a(Nb1-z-wTazSbw)O3, where a, x, y, z and w satisfy 0.9?a?1.2, 0.2?x?0.8, 0.0?y?0.2, 0?z?0.5 and 0?w?0.1, respectively.
    Type: Application
    Filed: July 6, 2010
    Publication date: January 13, 2011
    Applicant: NGK Insulators, Ltd.
    Inventors: Kazuyuki KAIGAWA, Ritsu Tanaka
  • Patent number: 7816847
    Abstract: A dielectric device of higher performance is provided. An electron emitter, to which the dielectric device is applied is provided with: an emitter including a dielectric; and an upper electrode and a lower electrode to which drive voltage is applied in order to emit electrons. The emitter is formed by the aerosol deposition method or the sol impregnation method.
    Type: Grant
    Filed: July 13, 2005
    Date of Patent: October 19, 2010
    Assignee: NGK Insulators, Ltd.
    Inventors: Tsutomu Nanataki, Hirofumi Yamaguchi, Ritsu Tanaka
  • Publication number: 20100022381
    Abstract: A (Li, Na, K)(Nb, Ta)O3-based piezoelectric/electrostrictive ceramic composition having large electric field-induced distortion at the time of application of a high electric field is provided. A perovskite oxide is synthesized which contains Li (lithium), Na (sodium) and K (potassium) as A-site elements and contains at least Nb (niobium) and Sb (antimony) out of Nb, Ta (tantalum) and Sb as B-site elements, the ratio of the total number of atoms of the A-site elements to the total number of atoms of the B-site elements being larger than 1, and then a Bi (bismuth) compound is added and reacted. The amount of addition of the Bi compound with respect to 100 molar parts of the perovskite oxide is preferably not less than 0.02 molar part nor more than 0.1 molar part in terms of Bi atoms.
    Type: Application
    Filed: July 22, 2009
    Publication date: January 28, 2010
    Applicant: NGK Insulators, Ltd.
    Inventors: Ritsu TANAKA, Hirofumi YAMAGUCHI
  • Publication number: 20100021728
    Abstract: Disclosed are piezoelectric materials in which electrical properties are improved, and manufacturing methods of the same. In (Li, Na, K, Bi)(Nb, Ta)O3 based piezoelectric materials, the surface microstructures of sintered bodies are constituted of microscopic grains having grain diameters of less than 5 ?m, intermediate grains having grain diameters of 5 ?m or more and less than 15 ?m, and coarse grains having grain diameters of 15 ?m or more and 100 ?m or less.
    Type: Application
    Filed: July 1, 2009
    Publication date: January 28, 2010
    Applicant: NGK Insulators, Ltd.
    Inventors: Kazuyuki KAIGAWA, Ritsu Tanaka, Hirofumi Yamaguchi
  • Publication number: 20100019624
    Abstract: An alkali niobate-based piezoelectric/electrostrictive ceramics sintered body including, as a main crystal phase, a perovskite type oxide containing at least one type of element selected from the group consisting of Li, Na and K as A site constituent elements and at least one type of element selected from the group consisting of Nb and Ta as B site constituent elements. The number of lattice-strained layers of the piezoelectric/electrostrictive ceramics sintered body is preferably small. A diffuse scattering intensity ratio, which is a ratio of an intensity of diffuse scattering by a lattice-strained layer present near a domain wall to a sum of an X-ray diffraction intensity of a first lattice plane and that of a second lattice plane different in interplanar spacing from the first lattice plane due to crystallographic symmetry reduction is preferably 0.5 or lower.
    Type: Application
    Filed: July 24, 2009
    Publication date: January 28, 2010
    Applicant: NGK Insulators, Ltd.
    Inventors: Kazuyuki KAIGAWA, Ritsu Tanaka, Hirofumi Yamaguchi
  • Publication number: 20100019187
    Abstract: There is disclosed a piezoelectric/electrostrictive ceramics which is a sintered body having a structure where a matrix and a filler are brought into a composite, the matrix is made of an alkali niobate-based piezoelectric/electrostrictive material, which includes a large number of grains combined with one another, including a perovskite type oxide, which includes at least one element selected from the group consisting of Li, Na and K as an A site constituent element and Nb as a B site constituent element, as a main crystal phase, the filler is made of a material (with the proviso that an alkali niobate-based material is excluded) having a thermal expansion coefficient smaller than that of the alkali niobate-based piezoelectric/electrostrictive material, and the volume fraction of the filler with respect to the total volume of the matrix and the filler is 0.5 vol % or more and below 10 vol %.
    Type: Application
    Filed: July 20, 2009
    Publication date: January 28, 2010
    Applicant: NGK Insulators, Ltd.
    Inventors: Kazuyuki Kaigawa, Ritsu Tanaka, Hirofumi Yamaguchi
  • Patent number: 7598659
    Abstract: A piezoelectric/electrostrictive device which exhibits an excellent piezoelectric characteristic and which has only a small dependence on a temperature is provided. The piezoelectric/electrostrictive device includes a piezoelectric/electrostrictive portion made of a piezoelectric ceramic, and electrodes electrically connected to the piezoelectric/electrostrictive portion. The piezoelectric ceramic reversibly transits to a tetragonal phase and an orthorhombic phase at a phase transition point as a boundary. The piezoelectric/electrostrictive portion is formed by a polarization treatment performed under the conditions that a treatment temperature ranges from a first temperature which exceeds the phase transition point of the piezoelectric ceramic to a second temperature which is 50° C. higher than the first temperature.
    Type: Grant
    Filed: March 13, 2007
    Date of Patent: October 6, 2009
    Assignee: NGK Insulators, Ltd.
    Inventors: Yukinobu Yura, Hirofumi Yamaguchi, Ritsu Tanaka
  • Publication number: 20090236556
    Abstract: A (Li, Na, K)(Nb, Ta)O3-based piezoelectric/electrostrictive ceramic composition having a large field-induced distortion during application of a high electric field is provided. After synthesizing a perovskite oxide containing Li (lithium), Na (sodium) and K (potassium) as A-site elements and containing at least Nb (niobium) out of the Nb and Ta (tantalum) as B-site elements, a ratio of total number of atoms of the A-site elements to total number of atoms of B-site elements being higher than 1, a Bi (bismuth) compound is added to the perovskite oxide and the perovskite oxide is reacted with the Bi compound. An addition amount of the Bi compound with respect to 100 molar parts of the perovskite oxide is preferably equal to or greater than 0.01 molar part and equal to or smaller than 0.1 molar part in terms of Bi atoms.
    Type: Application
    Filed: March 6, 2009
    Publication date: September 24, 2009
    Applicant: NGK Insulators, Ltd.
    Inventors: Ritsu Tanaka, Hirofumi Yamaguchi, Yukinobu Yura
  • Patent number: 7576477
    Abstract: A piezoelectric/electrostrictive porcelain composition is provided, including at least Nb, Ta, and one or more alkali metal elements, wherein a molar ratio of the Nb, Ta, and alkali metal element is represented by a non-stoichiometric composition ratio.
    Type: Grant
    Filed: March 7, 2006
    Date of Patent: August 18, 2009
    Assignee: NGK Insulators, Ltd.
    Inventors: Takaaki Koizumi, Hirofumi Yamaguchi, Ritsu Tanaka
  • Patent number: 7567021
    Abstract: A monomorph type piezoelectric/electrostrictive device includes a piezoelectric/electrostrictive body, which is composed of a non-lead based piezoelectric/electrostrictive crystalline body containing at least Nb, Ta, and one or more types of alkali metal element, which has a cubic crystal structure at a temperature higher than the phase transition point and at least any one of tetragonal and orthorhombic crystal structures at a temperature lower than the phase transition point, and which is curved to a large extent by a polarization treatment to take on a curved shape at a temperature lower than the phase transition point without application of a voltage after the polarization treatment. In the polarization treatment, an electric field is increased at a speed of from 0.1 (kV/mm)/sec or more to 5 (kV/mm)/sec or less, with applying the maximum electric field of from 2 kV/mm or more to 1.0 kV/mm or less.
    Type: Grant
    Filed: September 6, 2007
    Date of Patent: July 28, 2009
    Assignee: NGk Insulators, Ltd.
    Inventors: Ritsu Tanaka, Hirofumi Yamaguchi, Yukinobu Yura, Shuichi Ozawa