Patents by Inventor Akira Nagatomi

Akira Nagatomi 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: 7476338
    Abstract: To provide a phosphor having an emission spectrum with a broad peak in a range from yellow color to red color (580 nm to 680 nm) and an excellent excitation band on the longer wavelength side from near ultraviolet/ultraviolet of excitation light to visible light (250 nm to 550 nm), and having an improved emission intensity. The phosphor is provided, which is given by a general composition formula expressed by MmAaBbOoNn:Z, (wherein element M is more than one kind of element having bivalent valency, element A is more than one kind of element having tervalent valency selected from the group consisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb, and Bi, element B is more than one kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is more than one kind of element selected from rare earth elements or transitional metal elements, satisfying m>0, a>0, b>0 o?0, and n=2/3m+a+4/3b?2/3o), and further containing boron and/or fluorine.
    Type: Grant
    Filed: August 26, 2005
    Date of Patent: January 13, 2009
    Assignees: DOWA Electronics Materials Co., Ltd., Nichia Corporation
    Inventors: Kenji Sakane, Akira Nagatomi, Masahiro Gotoh, Shuji Yamashita, Tetsuya Ikuta
  • Patent number: 7476336
    Abstract: To provide a phosphor having an emission spectrum with a broad peak in range from green color to red color, and having excellent emission efficiency and luminance. A phosphor is provided, which is given by a general composition formula expressed by MmAaBbOoNn:Z, (where element M is more than one kind of element having bivalent valency, element A is more than one kind of element having tervalent valency, element B is more than one kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is more than one kind of element acting as an activator.), satisfying 2.5<(a+b)/m<4.5, 0<a/m<2.0, 2.0<b/m<4.0, 0<o/m<1.0, o<n, n=2/3m+a+4/3b?2/3o.
    Type: Grant
    Filed: June 10, 2005
    Date of Patent: January 13, 2009
    Assignee: DOWA Electronics Materials Co., Ltd.
    Inventors: Akira Nagatomi, Tetsuya Ikuta, Shuji Yamashita
  • Patent number: 7476335
    Abstract: To provide a phosphor having a broad emission spectrum with a peak in the range from yellow color to red color (wavelength from 570 nm to 620 nm), having a flat excitation band with large area on the long wavelength side from near ultraviolet/ultraviolet to green color (wavelength from 250 nm to 550 nm), and excellent in emission intensity and luminance, and a method of manufacturing the same, and also a light source such as white LED using the phosphor. As raw materials, Ca3N2(2N), AlN(3N), Si3N4(3N), and Eu2O3(3N) are prepared, and out of each raw material, 0.950/3 mol of Ca3N2, 2 mol of AlN, 4/3 mol of Si3N4, and 0.050/2 mol of Eu2O3 are weighed, and the raw materials thus weighed are mixed by using a mortar. The raw materials thus mixed are put in a BN crucible, and retained/fired for 3 hours at 1700° C. in a nitrogen atmosphere, and thereafter cooled from 1700° C. to 200° C., to thereby obtain the phosphor expressed by a composition formula Ca0.950Al2Si4O0.075N7.917:Eu0.050.
    Type: Grant
    Filed: February 23, 2005
    Date of Patent: January 13, 2009
    Assignees: Dowa Electronics Materials Co., Ltd., Nichia Corporation
    Inventors: Kenji Sakane, Akira Nagatomi
  • Patent number: 7477009
    Abstract: To provide a phosphor mixture realizing a light emitting device having a phosphor and a light emission element, by which light emission is performed, with a small color shift due to a feeding current and having an excellent color rendering properties. CaAlSin3:Eu as a red phosphor and YAG:Ce as a yellow phosphor are manufactured, and emission spectra thereof are obtained. Meanwhile, the emission spectrum of an excitation light emitted by a light emitting part is obtained. From the emission spectra thus obtained, a relative mixing ratio of each phosphor is obtained by simulation, so that a correlated color temperature of the light emitting device becomes a target temperature. Then, based on the relative mixing ratio thus obtained, each phosphor is measured and mixed, and a phosphor mixture is thereby obtained.
    Type: Grant
    Filed: August 8, 2005
    Date of Patent: January 13, 2009
    Assignees: DOWA Electronics Materials Co., Ltd., Nichia Corporation
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane
  • Publication number: 20080303412
    Abstract: A phosphor having an excitation band relative to lights in the wide range of wavelengths from ultraviolet to visible light, and having an emission spectrum in the red range and so on, with a wide half value width, and an LED and a light source using the phosphor and emitting white and other color lights with good color rendering properties are provided. Powdered raw materials of Ca3N2 (2N), CaO (2N), AlN (3N), Si3N4 (3N), and Eu2O3 (3N) are prepared, and the respective raw materials are mixed to have a mole ratio of the respective elements of Ca:Al:Si:Eu=0.985:1:1:0.015. The mixed raw materials are fired at 1000° C. or higher in an inert atmosphere for three hours, and thereafter pulverized to obtain a phosphor having a composition of CaAlSiN2.83O0.25:Eu, which is one example of the phosphor satisfying the above described object.
    Type: Application
    Filed: July 10, 2008
    Publication date: December 11, 2008
    Applicants: DOWA ELECTRONICS MATERIALS CO., LTD., NICHIA CORPORATION
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane, Shuji Yamashita
  • Patent number: 7445730
    Abstract: To provide a phosphor having a broad emission spectrum in a range of blue color (peak wavelength from 400 nm to 500 nm), having a broad and flat excitation band in the range of near ultraviolet/ultraviolet, and having excellent emission efficiency and emission intensity/luminance. The phosphor is expressed by a general composition formula MmAaBbOoNn:Z (where element M is at least one or more kind of element having bivalent valency, element A is at least one or more kind of element having tervalent valency, element B is at least one or more kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is at least one or more kind of element acting as an activator.), satisfying 5.0<(a+b)/m<9.0, 0?a/m?2.0, 0?o<n, n=2/3m+a+4/3b?2/3o, and having an emission spectrum with a maximum peak wavelength from 400 nm to 500 nm under an excitation of the light in a wavelength range from 350 nm to 430 nm.
    Type: Grant
    Filed: September 6, 2005
    Date of Patent: November 4, 2008
    Assignee: DOWA Electronics Materials Co., Ltd.
    Inventors: Akira Nagatomi, Kenji Sakane
  • Patent number: 7443094
    Abstract: A phosphor having an emission spectrum with a broad peak in a range of blue color and a broad and flat excitation band in a range of near ultraviolet/ultraviolet, and having an excellent emission efficiency and emission intensity/luminance, a manufacturing method of the same, and a light emitting device using the phosphor. The phosphor has a general composition formula expressed by MmAaBbOoNn:Z.
    Type: Grant
    Filed: June 10, 2005
    Date of Patent: October 28, 2008
    Assignee: DOWA Electronics Materials Co., Ltd.
    Inventors: Kenji Sakane, Akira Nagatomi
  • Patent number: 7432647
    Abstract: A phosphor having an excitation band relative to lights in the wide range of wavelengths from ultraviolet to visible light, and having an emission spectrum in the red range and so on, with a wide half value width, and an LED and a light source using the phosphor and emitting white and other color lights with good color rendering properties are provided. Powdered raw materials of Ca3N2 (2N), CaO (2N), AlN (3N), Si3N4 (3N), and Eu2O3 (3N) are prepared, and the respective raw materials are mixed to have a mole ratio of the respective elements of Ca:Al:Si:Eu=0.985:1:1:0.015. The mixed raw materials are fired at 1000° C. or higher in an inert atmosphere for three hours, and thereafter pulverized to obtain a phosphor having a composition of CaAlSiN2.83O0.25:Eu, which is one example of the phosphor satisfying the above described object.
    Type: Grant
    Filed: September 2, 2004
    Date of Patent: October 7, 2008
    Assignees: DOWA Electronics Materials Co., Ltd., Nichia Corporation
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane, Shuji Yamashita
  • Patent number: 7345418
    Abstract: A phosphor mixture containing four or more kinds of phosphors including a red phosphor, an orange phosphor, a blue phosphor, and a green phosphor, to produce emission having excellent color rendering of white light at a high color temperature, and emission in warm white which is low in color temperature, and a light emitting device including the phosphor mixture and a light-emitting section, CaAlSiN3:Eu and CaAl2Si4N8:Eu are manufactured as a red phosphor and an orange phosphor respectively, and ZnS:Cu, Al, and BAM:Eu are prepared as a green phosphor and a blue phosphor respectively. The emission spectrums of these phosphors are measured and a relative mixing ratio at which the correlated color temperature of the phosphor mixture becomes a targeted color temperature is determined from the emission spectrum by simulation, and a phosphor mixture is obtained by weighing and mixing the respective phosphors based on the simulation result.
    Type: Grant
    Filed: November 10, 2004
    Date of Patent: March 18, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane
  • Patent number: 7332220
    Abstract: An iron nitride magnetic powder consisting primarily of Fe16N2 phase whose average particle diameter determined by particle size measurement using a TEM micrograph is 20 nm or less and whose geometric standard deviation of the particle diameter is 1.4 or less. The iron nitride magnetic powder can be obtained by a method of producing an iron nitride magnetic powder consisting primarily of Fe16N2 phase includes a step of, at the time of producing an iron nitride magnetic powder consisting primarily of Fe16N2 phase by subjecting a reduced powder obtained by reduction of iron oxide to ammonia treatment, using goethite containing Al in solid solution as the iron oxide.
    Type: Grant
    Filed: February 25, 2005
    Date of Patent: February 19, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kenji Masada, Takafumi Amino, Akira Nagatomi
  • Patent number: 7291289
    Abstract: A phosphor with high efficiency having an excitation band corresponding to light of the ultraviolet-visible (300 to 550 nm) wavelength region emitted from a light emitting element which emits blue or ultraviolet light is provided. Commercially available CaO [3N], Si3N4 [3N], and Eu2O3 [3N] are prepared, respective materials are weighed and mixed to have a mol ratio of CaO:Si3N4:Eu2O3=1.4775:1:0.01125, and then the mixture is heated to 1600° C. by a heating rate of 15° C./min under a nitrogen atmosphere and retained and fired at 1600° C. for three hours. Thereafter, the raw materials are cooled down from 1600° C. to 200° C. for an hour to thereby produce a phosphor having a composition formula Ca1.58Si3O1.63N4.35:Eu0.024.
    Type: Grant
    Filed: August 20, 2004
    Date of Patent: November 6, 2007
    Assignee: Dowa Electronics Materials Co., Ltd.
    Inventors: Masahiro Gotoh, Akira Nagatomi, Kenji Sakane, Shuji Yamashita
  • Patent number: 7273568
    Abstract: A phosphor including a main production phase of a phosphor expressed by a composition formula of MmAaBbOoNn:Zz (where an element M is one or more bivalent elements, an element A is one or more trivalent elements, an element B is one or more tetravalent elements, O is oxygen, N is nitrogen, an element Z is an activator, n=2/3m+a+4/3b?2/3o, m/(a+b)?1/2, (o+n)/(a+b)>4/3, wherein m=a=b=1 and o and n is not 0). A phosphor including 24 wt % to 30 wt % of Ca (calcium), 17 wt % to 21 wt % of Al (aluminum), 18 wt % to 22 wt % of Si (silicon), 1 wt % to 15 wt % of oxygen, 15 wt % to 33 wt % of nitrogen and 0.01 wt % to 10 wt % of Eu (europium), wherein an emission maximum in an emission spectrum is in a range of 600 nm to 660 nm; and wherein color chromaticity x of light emission is in a range of 0.5 to 0.7, and color chromaticity y of the light emission is in a range of 0.3 to 0.5.
    Type: Grant
    Filed: August 20, 2004
    Date of Patent: September 25, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane, Shuji Yamashita
  • Patent number: 7252788
    Abstract: A phosphor with high efficiency having an excitation band corresponding to light of the ultraviolet-visible (300 to 550 nm) wavelength region emitted from a light emitting portion which emits blue or ultraviolet light is provided. A nitride of Ca, a nitride of Al, a nitride Si, and an oxide of Eu are prepared, and respective raw materials are weighed so that a mol ratio of respective elements becomes Ca:Al:Si:Eu=0.985:3:1:0.015, mixed under a nitrogen atmosphere, and thereafter fired at 1500° C. in a nitrogen atmosphere to thereby produce a phosphor having a composition formula Ca0.985SiAlN3:Eu0.015.
    Type: Grant
    Filed: August 20, 2004
    Date of Patent: August 7, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Nagatomi, Kenji Sakane, Masahiro Gotoh, Shuji Yamashita
  • Patent number: 7241501
    Abstract: An iron nitride magnetic powder comprised primarily of Fe16N2 phase is characterized in that its coercive force Hc is 200 KA/m or greater and bulk switching field distribution BSDF is 2 or less. The magnetic powder can be produced by allowing a nitriding reaction of Fe particles with a nitrogen-containing gas for producing nitrided particles of primarily Fe16N2 phase to proceed under an increased pressure of 0.1 MPa or greater. The enhanced properties of the iron nitride magnetic powder make it suitable as a magnetic material for high-density magnetic recording media.
    Type: Grant
    Filed: November 19, 2004
    Date of Patent: July 10, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kenji Masada, Takafumi Amino, Akira Nagatomi
  • Publication number: 20070029525
    Abstract: To provide a phosphor for an electron beam excitation with a small deterioration in an emission efficiency and capable of maintaining a high luminance, even when an excitation density of an electron beam for a phosphor excitation is increased. As raw materials, Ca3N2(2N), AlN(3N), Si3N4(3N), and Eu2O3(3N) are prepared, and the raw materials thus prepared are measured and mixed, so that a molar ratio of each element becomes (Ca+Eu):Al:Si=1:1:1. Then, the mixture thus obtained is maintained and fired for at 1500° C. for 3 hours, and thereafter crushed, to manufacture the phosphor having a composition formula Ca0.985SiAlN3:Eu0.015.
    Type: Application
    Filed: August 2, 2005
    Publication date: February 8, 2007
    Applicant: DOWA MINING CO., LTD.
    Inventors: Masahiro Gotoh, Akira Nagatomi, Kenji Sakane, Shuji Yamashita
  • Patent number: 7138756
    Abstract: A phosphor, which has less reduction in emission efficiency and is capable of keeping high luminance even when density of an electron beam for exciting the phosphor increases, is provided. As raw materials, Ca3N2 (2N), AlN (3N), Si3N4 (3N), and Eu2O3 (3N) are prepared, and each of the raw materials is weighed so that a mole ratio of each element is, for example, (Ca+Eu):Al:Si=1:1:1, and mixed, then the mixture is held and fired at 1500° C. under the inert atmosphere for three hours, and thereafter ground to produce a phosphor having a composition formula of Ca0.985SiAlN3:Eu0.
    Type: Grant
    Filed: September 27, 2004
    Date of Patent: November 21, 2006
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Masahiro Gotoh, Akira Nagatomi, Kenji Sakane, Shuji Yamashita
  • Publication number: 20060244356
    Abstract: To provide a phosphor having an emission spectrum with a broad peak in range from green color to red color, and having excellent emission efficiency and luminance. A phosphor is provided, which is given by a general composition formula expressed by MmAaBbOoNn:Z, (where element M is more than one kind of element having bivalent valency, element A is more than one kind of element having tervalent valency, element B is more than one kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is more than one kind of element acting as an activator.), satisfying 2.5<(a+b)/m<4.5, 0<a/m<2.0, 2.0<b/m<4.0, 0<o/m<1.0, o<n, n=2/3 m+a+4/3b?2/3o.
    Type: Application
    Filed: June 10, 2005
    Publication date: November 2, 2006
    Applicant: DOWA MINING CO., LTD.
    Inventors: Akira Nagatomi, Tetsuya Ikuta, Shuji Yamashita
  • Publication number: 20060220520
    Abstract: To provide a phosphor having an emission spectrum with a broad peak in a range of blue color (peak wavelength range from 400 nm to 500 nm) and a broad and flat excitation band in a range of near ultraviolet/ultraviolet, and having an excellent emission efficiency and emission intensity/luminance, a manufacturing method of the same, and a light emitting device using the phosphor. The phosphor is provided, which is given as a general composition formula expressed by MmAaBbOoNn:Z, (where element M is the element having bivalent valency, element A is the element having tervalent valency, element B is the element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is more than one kind of element acting as an activator.), satisfying 5.0<(a+b)/m<9.0, 0?a/m?2.0, 0?o<n, and n=2/3m+a+4/3b?2/3o, and having an emission spectrum with a maximum peak wavelength from 400 nm to 500 nm under an excitation of the light in a wavelength range from 350 nm to 430 nm.
    Type: Application
    Filed: June 10, 2005
    Publication date: October 5, 2006
    Applicant: DOWA MINING CO., LTD.
    Inventors: Kenji Sakane, Akira Nagatomi
  • Publication number: 20060220047
    Abstract: To provide a phosphor having a broad emission spectrum in a range of blue color (peak wavelength from 400 nm to 500 nm), having a broad and flat excitation band in the range of near ultraviolet/ultraviolet, and having excellent emission efficiency and emission intensity/luminance. The phosphor is expressed by a general composition formula MmAaBbOoNn:Z (where element M is more than one kind of element having bivalent valency, element A is more than one kind of element having tervalent valency, element B is more than one kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is more than one kind of element acting as an activator.), satisfying 5.0<(a+b)/m<9.0, 0?a/m?2.0, 0?o<n, n=2/3m+a+4/3b?2/3o, and having an emission spectrum with a maximum peak wavelength from 400 nm to 500 nm under an excitation of the light in a wavelength range from 350 nm to 430 nm.
    Type: Application
    Filed: September 6, 2005
    Publication date: October 5, 2006
    Applicant: DOWA MINING CO., LTD.
    Inventors: Akira Nagatomi, Kenji Sakane
  • Publication number: 20060197439
    Abstract: To provide a phosphor having an emission spectrum with a broad peak in a range from green color to yellow color, having a broad and flat excitation band capable of using lights of broad range from near ultraviolet/ultraviolet to blue lights as excitation lights, and having excellent emission efficiency and luminance. The problem is solved by providing the phosphor expressed by a general composition formula MmAaBbOoNn:Z (where element M is one or more kinds of elements having bivalent valency, element A is one or more kinds of elements having tervalent valency, element B is one or more kinds of elements having tetravalent valency, O is oxygen, N is nitrogen, and element Z is one or more kinds of elements acting as the activator.), satisfying 4.0<(a+b)/m<7.0, a/m?0.5, b/a>2.5, n>o, n=2/3 m+a+4/3 b?2/3 o.
    Type: Application
    Filed: March 2, 2006
    Publication date: September 7, 2006
    Applicant: DOWA MINING CO., LTD.
    Inventors: Kenji Sakane, Akira Nagatomi