Patents by Inventor Kenkichi Hara

Kenkichi Hara 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).

  • Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and a developer containing the carrier
    Patent number: 7470498
    Abstract: This invention provides an Mg-based ferrite carrier composed of an environment-friendly material meeting environmental regulations, and an electrophotographic developer comprising the carrier. The carrier and the developer of this invention realize high image quality and improved gradation properties. This invention also provides a method for producing the Mg-based ferrite material having a saturation magnetization of from 30 to 80 emu/g and a dielectric breakdown voltage of from 1.0 to 5.0 kV, and having the composition of the formula (1). The above properties are obtained by controlling conditions of sintering and heating treatments. CaaMgbFecOd (1) wherein a, b, and c satisfy 0.10 b/(b+c/2) 0.85 and 0 R(Ca) 0.10; R(Ca) is expressed as R(Ca)=a˜Fw(CaO)/(a˜Fw(CaO)+b˜Fw(MgO)+(c/2)˜Fw(Fc2O3)) (Fw(A): formula weight of A j; and d is determined by oxidation numbers of Ca, Mg and Fe.
    Type: Grant
    Filed: March 26, 2004
    Date of Patent: December 30, 2008
    Assignee: Kanto Denka Kogyo Co., Ltd.
    Inventors: Hidehiko Iinuma, Kenkichi Hara, Masatomo Hayashi
  • Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and a developer containing the carrier
    Publication number: 20060199093
    Abstract: This invention provides an Mg-based ferrite carrier composed of an environment-friendly material meeting environmental regulations, and an electrophotographic developer comprising the carrier. The carrier and the developer of this invention realize high image quality and improved gradation properties. This invention also provides a method for producing the Mg-based ferrite material having a saturation magnetization of from 30 to 80 emu/g and a dielectric breakdown voltage of from 1.0 to 5.0 kV, and having the composition of the formula (1). The above properties are obtained by controlling conditions of sintering and heating treatments. CaaMgbFecOd (1) wherein a, b, and c satisfy 0.10 b/(b+c/2)0.85 and 0 R(Ca) 0.10; R(Ca) is expressed as R(Ca)=a˜Fw(CaO)/(a˜Fw(CaO)+b˜Fw(MgO)+(c/2)˜Fw(Fc2O3))(Fw(A): formula weight of A j; and d is determined by oxidation numbers of Ca, Mg and Fe.
    Type: Application
    Filed: March 26, 2004
    Publication date: September 7, 2006
    Applicant: Kanto Denka Kogyo Co. Ltd.
    Inventors: Hidehiko Iinuma, Kenkichi Hara, Masatomo Hayashi
  • Method of making carrier for use in electrophotographic developers
    Patent number: 4751164
    Abstract: A novel carrier material useful in conjunction with a toner for preparing a two-component developer for electrophotographic processes is provided. The carrier comprises a spherical magnetite particulate material having a reduced metallic iron outer layer which is coated with an outermost resinous layer for conditioning the copying properties of the carrier.
    Type: Grant
    Filed: May 13, 1987
    Date of Patent: June 14, 1988
    Assignees: Kanto Denka Kogyo Co., Ltd., Hoganas AB
    Inventors: Mitsuhiro Katayama, Kenkichi Hara, Kazuyoshi Oka, Ulf Engstrom, Svenn E. Larssen
  • Carrier for use in electrophotographic developers
    Patent number: 4732835
    Abstract: A novel carrier material useful in conjunction with a toner for preparing a two-component developer for electrophotographic processes is provided. The carrier comprises a spherical magnetite particulate material having a reduced metallic iron outer layer which is coated with an outermost resinous layer for conditioning the copying properties of the carrier.
    Type: Grant
    Filed: June 9, 1986
    Date of Patent: March 22, 1988
    Assignees: Kanto Denka Kogyo Co., Ltd., Hoganas AB
    Inventors: Mitsuhiro Katayama, Kenkichi Hara, Kazuyoshi Oka, Ulf Engstrom, Svenn E. Larrssen
  • Two-component resin system of acrylic and diene polymers for coating electrophotographic carrier particles
    Patent number: 4503136
    Abstract: A carrier for use as a component in electrophotographic two-component developers which is improved in durability of the triboelectric property by coating the surface of the iron core particles of carrier with a resinous composition comprised essentially of an epoxy-hydroxy hydrocarbon resin and an acrylic resin.
    Type: Grant
    Filed: January 24, 1983
    Date of Patent: March 5, 1985
    Assignees: Kanto Denka Kogyo Co., Ltd., Tokyo Shibaura Denki Kabushiki Kaisha
    Inventors: Kenkichi Hara, Shigeo Yokoe, Kazuyoshi Oka, Tamotsu Murakami, Tsugifusa Hashimoto
  • Resin-coated carrier for use in two-component electrophotographic developers
    Patent number: 4486502
    Abstract: A carrier for use as a component in electrophotographic two-component developers which is improved in durability of the triboelectric property by coating the surface of the iron core particles of carrier with a resinous composition comprised essentially of an epoxy-hydroxy hydrocarbon resin and a silicone resin.
    Type: Grant
    Filed: January 4, 1983
    Date of Patent: December 4, 1984
    Assignees: Kanto Denka Kogyo Co. Ltd., Tokyo Shibaura Denki Kabushiki Kaisha
    Inventors: Kenkichi Hara, Shigeo Yokoe, Kazuyoshi Oka, Tamotsu Murakami, Tsugifusa Hashimoto