Patents by Inventor Norikazu Koyuhara

Norikazu Koyuhara 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: 11398328
    Abstract: A sintered MnZn ferrite body containing main components comprising 53.30-53.80% by mol of Fe calculated as Fe2O3, 6.90-9.50% by mol Zn calculated as ZnO, and the balance of Mn calculated as MnO, and sub-components comprising 0.003-0.020 parts by mass of Si calculated as SiO2, more than 0 parts and 0.35 parts or less by mass of Ca calculated as CaCO3, 0.30-0.50 parts by mass of Co calculated as Co3O4, 0.03-0.10 parts by mass of Zr calculated as ZrO2, and 0-0.05 parts by mass of Ta calculated as Ta2O5, pre 100 parts by mass in total of the main components (calculated as the oxides), and having an average crystal grain size of 3 ?m or more and less than 8 ?m and a density of 4.65 g/cm3 or more.
    Type: Grant
    Filed: March 27, 2018
    Date of Patent: July 26, 2022
    Assignee: HITACHI METALS, LTD.
    Inventors: Yasuharu Miyoshi, Tomoyuki Tada, Norikazu Koyuhara
  • Patent number: 11242288
    Abstract: A sintered Ni ferrite body having a composition comprising, calculated as oxide, 47.0-48.3% by mol of Fe2O3, 14.5% or more and less than 25% by mol of ZnO, 8.2-10.0% by mol of CuO, and more than 0.6% and 2.5% or less by mol of CoO, the balance being NiO and inevitable impurities, and having an average crystal grain size of more than 2.5 ?m and less than 5.5 ?m.
    Type: Grant
    Filed: March 15, 2018
    Date of Patent: February 8, 2022
    Assignee: HITACHI METALS, LTD.
    Inventors: Satoru Tanaka, Norikazu Koyuhara, Tomoyuki Tada
  • Publication number: 20210139377
    Abstract: A sintered Ni ferrite body having a composition comprising, calculated as oxide, 47.0-48.3% by mol of Fe2O3, 14.5% or more and less than 25% by mol of ZnO, 8.2-10.0% by mol of CuO, and more than 0.6% and 2.5% or less by mol of CoO, the balance being NiO and inevitable impurities, and having an average crystal grain size of more than 2.5 ?m and less than 5.5 ?m.
    Type: Application
    Filed: March 15, 2018
    Publication date: May 13, 2021
    Applicant: HITACHI METALS, LTD.
    Inventors: Satoru TANAKA, Norikazu KOYUHARA, Tomoyuki TADA
  • Patent number: 10950375
    Abstract: A method for producing a MnZn ferrite core used at a frequency of 1 MHz or more and an exciting magnetic flux density of 75 mT or less, the MnZn ferrite comprising 53-56% by mol of Fe (calculated as Fe2O3), and 3-9% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and 0.05-0.4 parts by mass of Co (calculated as Co3O4) as a sub-component, per 100 parts by mass in total of the main components (calculated as the oxides); comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body; a step of sintering the green body and cooling it to a temperature of lower than 150° C. to obtain a sintered body of MnZn ferrite; and a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting Condition 1 of 200° C. or higher, and Condition 2 of (Tc?90)° C. to (Tc+100)° C., wherein Tc is a Curie temperature (° C.
    Type: Grant
    Filed: March 24, 2017
    Date of Patent: March 16, 2021
    Assignee: HITACHI METALS. LTD.
    Inventors: Norikazu Koyuhara, Yasuharu Miyoshi, Tomoyuki Tada, Satoru Tanaka
  • Patent number: 10937579
    Abstract: A method for producing MnZn-ferrite comprising Fe, Mn and Zn as main components, and at least Co, Si and Ca as sub-components, the main components in the MnZn-ferrite comprising 53-56% by mol (as Fe2O3) of Fe, and 3-9% by mol (as ZnO) of Zn, the balance being Mn as MnO, comprising the step of sintering a green body to obtain MnZn-ferrite; the sintering comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step; the high-temperature-keeping step being conducted at a keeping temperature of higher than 1050° C. and lower than 1150° C. in an atmosphere having an oxygen concentration of 0.4-2% by volume; the oxygen concentration being in a range of 0.001-0.2% by volume during cooling from 900° C. to 400° C. in the cooling step; and the cooling speed between (Tc+70)° C. and 100° C. being 50° C./hour or more, wherein Tc represents a Curie temperature (° C.) calculated from % by mass of Fe2O3 and ZnO.
    Type: Grant
    Filed: December 24, 2015
    Date of Patent: March 2, 2021
    Assignee: HITACHI METALS, LTD.
    Inventors: Norikazu Koyuhara, Yasuharu Miyoshi, Tomoyuki Tada, Satoru Tanaka
  • Patent number: 10919809
    Abstract: A method for producing MnZn ferrite comprising Fe, Mn and Zn as main components, and Ca, Si and Co, and at least one selected from the group consisting of Ta, Nb and Zr as sub-components, comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body, and a step of sintering the green body; the sintering step comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step; the cooling step including a slow cooling step of cooling in a temperature range of 1100° C. to 1250° C. at a cooling speed of 0° C./hour to 20° C./hour for 1 hours to 20 hours, and a cooling speed before and after the slow cooling step being higher than 20° C./hour; the MnZn ferrite having a volume resistivity of 8.5 ?·m or more at room temperature, an average crystal grain size of 7 ?m to 15 ?m, and core loss of 420 kW/m3 or less between 23° C. and 140° C. at a frequency of 100 kHz and an exciting magnetic flux density of 200 mT.
    Type: Grant
    Filed: March 24, 2017
    Date of Patent: February 16, 2021
    Assignee: HITACHI METALS, LTD.
    Inventors: Yasuharu Miyoshi, Norikazu Koyuhara, Tomoyuki Tada
  • Publication number: 20200373047
    Abstract: A sintered MnZn ferrite body containing main components comprising 53.30-53.80% by mol of Fe calculated as Fe2O3, 6.90-9.50% by mol Zn calculated as ZnO, and the balance of Mn calculated as MnO, and sub-components comprising 0.003-0.020 parts by mass of Si calculated as SiO2, more than 0 parts and 0.35 parts or less by mass of Ca calculated as CaCO3, 0.30-0.50 parts by mass of Co calculated as Co3O4, 0.03-0.10 parts by mass of Zr calculated as ZrO2, and 0-0.05 parts by mass of Ta calculated as Ta2O5, pre 100 parts by mass in total of the main components (calculated as the oxides), and having an average crystal grain size of 3 ?m or more and less than 8 ?m and a density of 4.65 g/cm3 or more.
    Type: Application
    Filed: March 27, 2018
    Publication date: November 26, 2020
    Applicant: HITACHI METALS, LTD.
    Inventors: Yasuharu MIYOSHI, Tomoyuki TADA, Norikazu KOYUHARA
  • Patent number: 10304602
    Abstract: Provided are: a MnZn-based ferrite which allows to have a low magnetic core loss and to suppress a time-dependent change of magnetic property under a high-temperature environment by a control of ambient oxygen concentration and an increase of the magnetic core loss, and a method for manufacturing the same. The MnZn-based ferrite is characterized in that Fe ranges from 53.25 mol % or more to 54.00 mol % or less on the basis of Fe2O3, Zn ranges from 2.50 mol % or more to 8.50 mol % or less on the basis of ZnO and Mn is the remainder on the basis of MnO, Si ranges from more than 0.001 mass % to less than 0.02 mass % on the basis of SiO2, Ca ranges from more than 0.04 mass % to less than 0.4 mass % on the basis of CaCO3, Co is less than 0.5 mass % on the basis of Co3O4, Bi is less than 0.05 mass % on the basis of Bi2O3, Ta is less than 0.05 mass % on the basis of Ta2O5, Nb is less than 0.05 mass % on the basis of Nb2O5, Ti is less than 0.3 mass % on the basis of TiO2, and Sn is less than 0.
    Type: Grant
    Filed: August 31, 2015
    Date of Patent: May 28, 2019
    Assignee: Hitachi Metals, Ltd.
    Inventors: Tomoyuki Tada, Yasuharu Miyoshi, Norikazu Koyuhara
  • Publication number: 20190096554
    Abstract: A method for producing a MnZn ferrite core used at a frequency of 1 MHz or more and an exciting magnetic flux density of 75 mT or less, the MnZn ferrite comprising 53-56% by mol of Fe (calculated as Fe2O3), and 3-9% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and 0.05-0.4 parts by mass of Co (calculated as Co3O4) as a sub-component, per 100 parts by mass in total of the main components (calculated as the oxides); comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body; a step of sintering the green body and cooling it to a temperature of lower than 150° C. to obtain a sintered body of MnZn ferrite; and a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting Condition 1 of 200° C. or higher, and Condition 2 of (Tc?90)° C. to (Tc+100) ° C., wherein Tc is a Curie temperature (° C.
    Type: Application
    Filed: March 24, 2017
    Publication date: March 28, 2019
    Applicant: HITACHI METALS, LTD.
    Inventors: Norikazu KOYUHARA, Yasuharu MIYOSHI, Tomoyuki TADA, Satoru TANAKA
  • Publication number: 20190062217
    Abstract: A method for producing MnZn ferrite comprising Fe, Mn and Zn as main components, and Ca, Si and Co, and at least one selected from the group consisting of Ta, Nb and Zr as sub-components, comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body, and a step of sintering the green body; the sintering step comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step; the cooling step including a slow cooling step of cooling in a temperature range of 1100° C. to 1250° C. at a cooling speed of 0° C./hour to 20° C./hour for 1 hours to 20 hours, and a cooling speed before and after the slow cooling step being higher than 20° C./hour; the MnZn ferrite having a volume resistivity of 8.5 ?·m or more at room temperature, an average crystal grain size of 7 ?m to 15 ?m, and core loss of 420 kW/m3 or less between 23° C. and 140° C. at a frequency of 100 kHz and an exciting magnetic flux density of 200 mT.
    Type: Application
    Filed: March 24, 2017
    Publication date: February 28, 2019
    Applicant: HITACHI METALS, LTD.
    Inventors: Yasuharu MIYOSHI, Norikazu KOYUHARA, Tomoyuki TADA
  • Publication number: 20170352455
    Abstract: A method for producing MnZn-ferrite comprising Fe, Mn and Zn as main components, and at least Co, Si and Ca as sub-components, the main components in the MnZn-ferrite comprising 53-56% by mol (as Fe2O3) of Fe, and 3-9% by mol (as ZnO) of Zn, the balance being Mn as MnO, comprising the step of sintering a green body to obtain MnZn-ferrite; the sintering comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step; the high-temperature-keeping step being conducted at a keeping temperature of higher than 1050° C. and lower than 1150° C. in an atmosphere having an oxygen concentration of 0.4-2% by volume; the oxygen concentration being in a range of 0.001-0.2% by volume during cooling from 900° C. to 400° C. in the cooling step; and the cooling speed between (Tc+70)° C. and 100° C. being 50° C./hour or more, wherein Tc represents a Curie temperature (° C.) calculated from % by mass of Fe2O3 and ZnO.
    Type: Application
    Filed: December 24, 2015
    Publication date: December 7, 2017
    Applicant: HITACHI METALS, LTD.
    Inventors: Norikazu KOYUHARA, Yasuharu MIYOSHI, Tomoyuki TADA, Satoru TANAKA
  • Publication number: 20170278607
    Abstract: Provided are: a MnZn-based ferrite which allows to have a low magnetic core loss and to suppress a time-dependent change of magnetic property under a high-temperature environment by a control of ambient oxygen concentration and an increase of the magnetic core loss, and a method for manufacturing the same. The MnZn-based ferrite is characterized in that Fe ranges from 53.25 mol % or more to 54.00 mol % or less on the basis of Fe2O3, Zn ranges from 2.50 mol % or more to 8.50 mol % or less on the basis of ZnO and Mn is the remainder on the basis of MnO, Si ranges from more than 0.001 mass % to less than 0.02 mass % on the basis of SiO2, Ca ranges from more than 0.04 mass % to less than 0.4 mass % on the basis of CaCO3, Co is less than 0.5 mass % on the basis of Co3O4, Bi is less than 0.05 mass % on the basis of Bi2O3, Ta is less than 0.05 mass % on the basis of Ta2O5, Nb is less than 0.05 mass % on the basis of Nb2O5, Ti is less than 0.3 mass % on the basis of TiO2, and Sn is less than 0.
    Type: Application
    Filed: August 31, 2015
    Publication date: September 28, 2017
    Applicant: Hitachi Metals, Ltd.
    Inventors: Tomoyuki Tada, Yasuharu Miyoshi, Norikazu Koyuhara
  • Patent number: 7061355
    Abstract: A ferrite core for use in coupling transformers and distributing transformers in CATV equipments such as couplers, distributors and amplifiers, the ferrite core being made of a ferrite having a saturation magnetostriction |?S| of 8×10?6 or less in an absolute value and an initial permeability ?i of 300 or more.
    Type: Grant
    Filed: August 28, 2003
    Date of Patent: June 13, 2006
    Assignee: Hitachi Metals, Ltd.
    Inventors: Satoru Tanaka, Norikazu Koyuhara, Makoto Kadowaki, Yoshihito Yoshikawa, Shiro Murakami
  • Publication number: 20040113742
    Abstract: A ferrite core for use in coupling transformers and distributing transformers in CATV equipments such as couplers, distributors and amplifiers, the ferrite core being made of a ferrite having a saturation magnetostriction |&lgr;s| of 8×10−6 or less in an absolute value and an initial permeability &mgr;i of 300 or more.
    Type: Application
    Filed: August 28, 2003
    Publication date: June 17, 2004
    Applicant: HITACHI METALS, LTD.
    Inventors: Satoru Tanaka, Norikazu Koyuhara, Makoto Kadowaki, Yoshihito Yoshizawa, Shiro Murakami
  • Patent number: 5815062
    Abstract: In the magnetic core including a first leg portion around which a wire is wound, a second leg portion for circulating a magnetic flux generated in the first leg portion, and a web portion connecting the first leg portion and the second leg portion, a magnetic gap is provided in a rear area extending from the root of the first leg portion. With the magnetic gap, a magnetic flux leaking outwardly from a rear area extending from the root of the first leg portion is drastically reduced.
    Type: Grant
    Filed: February 28, 1997
    Date of Patent: September 29, 1998
    Assignees: Hitachi Metal, Ltd., Hitachi Ferrite Electronics, Ltd.
    Inventors: Norikazu Koyuhara, Youichi Yamamoto, Toshihiko Tanaka
  • Patent number: 5618464
    Abstract: A Ni ferrite sintered body comprising 48.0-50.0 mol % of Fe.sub.2 O.sub.3, 14.0-24.0 mol % of NiO and 28.0-36.0 mol % of ZnO with 50 ppm or less of P as an impurity, the sintered body having a minimum core loss of 30 kW/m.sup.3 or less at 50 kHz and 50 mT, and the segregation percentage of P in the crystal structure being 1% or less by area. The Ni ferrite sintered body preferably has an average crystal grain size of 3-30 .mu.m, the percentage of crystal grain particles larger than two times the average crystal grain size being preferably 10% or less based on the total number of the crystal grain particles in a crystal structure.
    Type: Grant
    Filed: March 13, 1995
    Date of Patent: April 8, 1997
    Assignee: Hitachi Ferrite, Ltd.
    Inventors: Emi Nakagawa, Hitoshi Ueda, Akio Uchikawa, Norikazu Koyuhara