Patents by Inventor Toshio Honjo

Toshio Honjo 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: 8628905
    Abstract: A ferrite core material for a resin-filled type carrier, and a resin-filled type carrier which is used as an electrophotographic developer by mixing a toner, sufficiently secure the image density, have no carrier adhesion and can maintain high-quality images over a long period, and an electrophotographic developer using the carrier, are provided. A ferrite core material for a resin-filled type carrier characterized in a void fraction of 10 to 60%, a resin-filled type carrier filled in the carrier core material with a resin, and an electrophotographic developer composed of the resin-filled type carrier and a toner, are provided.
    Type: Grant
    Filed: May 31, 2006
    Date of Patent: January 14, 2014
    Assignee: Powdertech Co. Ltd.
    Inventors: Hiromichi Kobayashi, Tsuyoshi Itagoshi, Tomoyuki Suwa, Toshio Honjo
  • Publication number: 20120076551
    Abstract: An object of the present invention is to provide a resin-coated ferrite carrier comprising a carrier core material having a small particle size, a high sphericity and surface uniformity, and a low standard deviation, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated ferrite carrier and having a high image quality and excellent durability. For achieving the above object, there is provided a resin-coated carrier for an electrophotographic developer characterized by comprising spherical ferrite particles having an average particle size of 20 to 50 ?m, a surface uniformity of 90% or more, an average sphericity of 1 to 1.3 and a sphericity standard deviation of 0.15 or less, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated carrier.
    Type: Application
    Filed: December 7, 2011
    Publication date: March 29, 2012
    Applicant: POWDERTECH CO., LTD.
    Inventors: Kanao KAYAMOTO, Hironori HOJO, Toshio HONJO
  • Patent number: 8092971
    Abstract: An object of the present invention is to provide a resin-coated ferrite carrier comprising a carrier core material having a small particle size, a high sphericity and surface uniformity, and a low standard deviation, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated ferrite carrier and having a high image quality and excellent durability. For achieving the above object, there is provided a resin-coated carrier for an electrophotographic developer characterized by comprising spherical ferrite particles having an average particle size of 20 to 50 ?m, a surface uniformity of 90% or more, an average sphericity of 1 to 1.3 and a sphericity standard deviation of 0.15 or less, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated carrier.
    Type: Grant
    Filed: November 25, 2004
    Date of Patent: January 10, 2012
    Assignee: Powdertech Co., Ltd.
    Inventors: Kanao Kayamoto, Hironori Hojo, Toshio Honjo
  • Patent number: 7824833
    Abstract: A spherical resin-coated ferrite carrier for an electrophotographic developer which can maintain a stable resistance and chargeability, a favorable charge rising property because of an excellent fluidity, and has a suitable durability, its production method which is excellent in economic efficiency and production stability, and an electrophotographic developer using the resin-coated ferrite carrier, are provided. A resin-coated ferrite carrier for an electrophotographic developer which is a spherical resin-coated ferrite carrier, wherein a carrier core material thereof has an irregular surface to improve the adhesive strength to a resin coat, and wherein the irregularity of the surface takes a finely streaked wrinkle pattern, its production method, and an electrophotographic developer using the resin-coated ferrite carrier, are employed.
    Type: Grant
    Filed: November 30, 2006
    Date of Patent: November 2, 2010
    Assignee: Powdertech Co., Ltd.
    Inventors: Kanao Kayamoto, Issei Shinmura, Toshio Honjo
  • Patent number: 7598011
    Abstract: It is contemplated to provide irregular shaped ferrite carrier which has a lower resistance, a high specific surface area, a low specific gravity and a longer operational life, and an electrophotographic developer comprising the ferrite carrier which prevents the toner scattering, has a high image density, and is responsive to high-speed and color imaging. The irregular shaped ferrite carrier is characterized in that the carrier particles are irregular shaped, and 40 percent by number or more of the particles have a rock candy sugar shape and/or an oyster shell shape, and that the shape factor (SF-1=R2/S×?/4×100, wherein R is a maximum length and S is a projected area.) is 140 to 250, and the distribution width (?) is 60 or less.
    Type: Grant
    Filed: February 28, 2006
    Date of Patent: October 6, 2009
    Assignee: Powdertech Co., Ltd.
    Inventors: Hiromichi Kobayashi, Toru Iwata, Toshio Honjo
  • Patent number: 7566519
    Abstract: A carrier for an electrophotographic developer which is used as an electrophotographic developer in a mixture with a toner and which secures sufficiently the image density and can maintain high-quality images for a long period, and an electrophotographic developer using the carrier, are provided. A resin-filled ferrite carrier for electrophotographic developer obtained by filling, with a resin, avoid of a porous ferrite core whose void continues from the surface to reach the interior of the core, the carrier comprising a plurality of three-dimensional laminate structures in which resin layers and ferrite layers are alternately present, and an electrophotographic developer including the carrier and a toner, are employed.
    Type: Grant
    Filed: August 25, 2006
    Date of Patent: July 28, 2009
    Assignee: Powdertech Co., Ltd.
    Inventors: Hiromichi Kobayashi, Tsuyoshi Itagoshi, Tomoyuki Suwa, Toshio Honjo
  • Publication number: 20090130587
    Abstract: A spherical resin-coated ferrite carrier for an electrophotographic developer which can maintain a stable resistance and chargeability, a favorable charge rising property because of an excellent fluidity, and has a suitable durability, its production method which is excellent in economic efficiency and production stability, and an electrophotographic developer using the resin-coated ferrite carrier, are provided. A resin-coated ferrite carrier for an electrophotographic developer which is a spherical resin-coated ferrite carrier, wherein a carrier core material thereof has an irregular surface to improve the adhesive strength to a resin coat, and wherein the irregularity of the surface takes a finely streaked wrinkle pattern, its production method, and an electrophotographic developer using the resin-coated ferrite carrier, are employed.
    Type: Application
    Filed: November 30, 2006
    Publication date: May 21, 2009
    Applicant: POWDERTECH CO., LTD.
    Inventors: Kanao Kayamoto, Issei Shinmura, Toshio Honjo
  • Patent number: 7521163
    Abstract: A resin-coated ferrite carrier having a uniform resin coating and emitting no offensive odors, etc., its production method, and an electrophotographic developer which comprises the resin-coated ferrite carrier, is excellent in the charge stability and image quality stability over a long period, causes less fogging of image or carrier adhesion, is favorable in the image density and environmental dependency, and can fully respond to high-speed and full-color imaging, are provided. The resin-coated ferrite carrier for the electrophotographic developer is characterized in that the surface of ferrite particles is coated with a mixed resin of a tetrafluoroethylene-hexafluoropropylene copolymer or a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer and a polyamideimide resin, and that the mixed resin contains a silicon oxide.
    Type: Grant
    Filed: November 14, 2005
    Date of Patent: April 21, 2009
    Assignee: Powdertech Co., Ltd.
    Inventors: Tetsuya Uemura, Toshio Honjo, Kanao Kayamoto
  • Patent number: 7442483
    Abstract: A ferrite carrier for the electrophotographic developer containing 40 to 500 ppm of zirconium; a method for preparing a ferrite carrier for the electrophotographic developer, comprising the steps for weighing, mixing, and pulverizing ferrite raw materials, and for granulating, drying, and firing the obtained slurry; wherein a zirconium raw material is added so that the zirconium content after firing becomes 40 to 500 ppm; and an electrophotographic developer using the ferrite carrier.
    Type: Grant
    Filed: June 28, 2005
    Date of Patent: October 28, 2008
    Assignee: Powdertech Co., Ltd.
    Inventors: Hiromichi Kobayashi, Kanao Kayamoto, Tadashi Harayama, Issei Shinmura, Toshio Honjo
  • Publication number: 20070154833
    Abstract: An object of the present invention is to provide a resin-coated ferrite carrier comprising a carrier core material having a small particle size, a high sphericity and surface uniformity, and a low standard deviation, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated ferrite carrier and having a high image quality and excellent durability. For achieving the above object, there is provided a resin-coated carrier for an electrophotographic developer characterized by comprising spherical ferrite particles having an average particle size of 20 to 50 ?m, a surface uniformity of 90% or more, an average sphericity of 1 to 1.3 and a sphericity standard deviation of 0.15 or less, a process for producing the carrier, and an electrophotographic developer comprising the resin-coated carrier.
    Type: Application
    Filed: November 25, 2004
    Publication date: July 5, 2007
    Applicant: POWDERTECH CO., LTD.
    Inventors: Kanao Kayamoto, Hironori Hojo, Toshio Honjo
  • Publication number: 20070141502
    Abstract: A ferrite carrier core material for electrophotography having a homogeneous composition, a certain surface property, a favorable fluidity, a high magnetization and a low resistance, and a ferrite carrier for electrophotography methods for producing them, and an electrophotographic developer using the ferrite carrier-core material, which exhibits a fast charge rising and a stable charge quantity with time, are provided. A ferrite carrier core material for electrophotography whose surface is divided by grooves or streaks into 2 to 50 regions per 10 ?m and which has a manganese ferrite as a main component, and a method for producing the ferrite carrier core material for electrophotography using an Fe—Mn composite oxide as the raw material, and a method for producing a ferrite carrier for electrophotography are employed.
    Type: Application
    Filed: June 5, 2006
    Publication date: June 21, 2007
    Applicant: POWDERTECH CO., LTD.
    Inventors: Koji Aga, Takeshi Naito, Tetsuya Igarashi, Toshio Honjo
  • Publication number: 20070048649
    Abstract: A carrier for an electrophotographic developer which is used as an electrophotographic developer in a mixture with a toner and which secures sufficiently the image density and can maintain high-quality images for a long period, and an electrophotographic developer using the carrier, are provided. A resin-filled ferrite carrier for electrophotographic developer obtained by filling, with a resin, avoid of a porous ferrite core whose void continues from the surface to reach the interior of the core, the carrier comprising a plurality of three-dimensional laminate structures in which resin layers and ferrite layers are alternately present, and an electrophotographic developer including the carrier and a toner, are employed.
    Type: Application
    Filed: August 25, 2006
    Publication date: March 1, 2007
    Applicant: POWDERTECH CO., LTD.
    Inventors: Hiromichi Kobayashi, Tsuyoshi Itagoshi, Tomoyuki Suwa, Toshio Honjo
  • Publication number: 20060269862
    Abstract: A ferrite core material for a resin-filled type carrier, and a resin-filled type carrier which is used as an electrophotographic developer by mixing a toner, sufficiently secure the image density, have no carrier adhesion and can maintain high-quality images over a long period, and an electrophotographic developer using the carrier, are provided. A ferrite core material for a resin-filled type carrier characterized in a void fraction of 10 to 60%, a resin-filled type carrier filled in the carrier core material with a resin, and an electrophotographic developer composed of the resin-filled type carrier and a toner, are provided.
    Type: Application
    Filed: May 31, 2006
    Publication date: November 30, 2006
    Applicant: POWDERTECH CO., LTD.
    Inventors: Hiromichi Kobayashi, Tsuyoshi Itagoshi, Tomoyuki Suwa, Toshio Honjo
  • Publication number: 20060194137
    Abstract: It is contemplated to provide irregular shaped ferrite carrier which has a lower resistance, a high specific surface area, a low specific gravity and a longer operational life, and an electrophotographic developer comprising the ferrite carrier which prevents the toner scattering, has a high image density, and is responsive to high-speed and color imaging. The irregular shaped ferrite carrier is characterized in that the carrier particles are irregular shaped, and 40 percent by number or more of the particles have a rock candy sugar shape and/or an oyster shell shape, and that the shape factor (SF-1=R2/S×?/4×100, wherein R is a maximum length and S is a projected area.) is 140 to 250, and the distribution width (?) is 60 or less.
    Type: Application
    Filed: February 28, 2006
    Publication date: August 31, 2006
    Applicant: POWDERTECH CO., LTD.
    Inventors: Hiromichi Kobayashi, Toru Iwata, Toshio Honjo
  • Publication number: 20060121385
    Abstract: A resin-coated ferrite carrier having a uniform resin coating and emitting no offensive odors, etc., its production method, and an electrophotographic developer which comprises the resin-coated ferrite carrier, is excellent in the charge stability and image quality stability over a long period, causes less fogging of image or carrier adhesion, is favorable in the image density and environmental dependency, and can fully respond to high-speed and full-color imaging, are provided. The resin-coated ferrite carrier for the electrophotographic developer is characterized in that the surface of ferrite particles is coated with a mixed resin of a tetrafluoroethylene-hexafluoropropylene copolymer or a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer and a polyamideimide resin, and that the mixed resin contains a silicon oxide.
    Type: Application
    Filed: November 14, 2005
    Publication date: June 8, 2006
    Applicant: POWDERTECH CO., LTD.
    Inventors: Tetsuya Uemura, Toshio Honjo, Kanao Kayamoto
  • Publication number: 20060003248
    Abstract: A ferrite carrier for the electrophotographic developer containing 40 to 500 ppm of zirconium; a method for preparing a ferrite carrier for the electrophotographic developer, comprising the steps for weighing, mixing, and pulverizing ferrite raw materials, and for granulating, drying, and firing the obtained slurry; wherein a zirconium raw material is added so that the zirconium content after firing becomes 40 to 500 ppm; and an electrophotographic developer using the ferrite carrier.
    Type: Application
    Filed: June 28, 2005
    Publication date: January 5, 2006
    Applicant: POWDERTECH CO., LTD.
    Inventors: Hiromichi Kobayashi, Kanao Kayamoto, Tadashi Harayama, Issei Shinmura, Toshio Honjo
  • Patent number: 6124068
    Abstract: A carrier for an electrophotographic developer comprising a carrier core coated with a silicone resin containing a quaternary ammonium salt as a catalyst.
    Type: Grant
    Filed: December 24, 1998
    Date of Patent: September 26, 2000
    Assignee: Powdertech Co., Ltd.
    Inventors: Hiromichi Kobayashi, Yuji Sato, Toshio Honjo
  • Patent number: 6071663
    Abstract: A carrier for an electrophotographic developer comprising a carrier core coated with a silicone resin containing a crosslinking agent having a phenyl group.
    Type: Grant
    Filed: December 24, 1998
    Date of Patent: June 6, 2000
    Assignee: Powdertech Co., Ltd.
    Inventors: Shinichi Matsuda, Yuji Sato, Hiromichi Kobayashi, Yasuhiko Kataoka, Tetsuya Uemura, Toshio Honjo
  • Patent number: 5976747
    Abstract: A ferrite carrier for electrophotographic developers which is represented by formula:(MnO).sub.x (MgO).sub.y (Fe.sub.2 O.sub.3).sub.zwherein x+y+z=100 mol %, and part of MnO, MgO and/or Fe.sub.2 O.sub.3 is substituted with SnO.sub.2, and has a saturation magnetization of 20 to 43 emu/g.
    Type: Grant
    Filed: February 26, 1998
    Date of Patent: November 2, 1999
    Assignee: Powdertech Co., Ltd.
    Inventors: Yuji Sato, Tsuyoshi Itagoshi, Kazunori Takagi, Norio Takei, Toshio Honjo
  • Patent number: 5965317
    Abstract: A method for regenerating a carrier coated with a silicone resin or a resin containing a silane coupling agent in an electrophotographic developer comprising the carrier and a toner, which comprises separating the developer into the carrier and the toner, immersing the separated carrier in an aqueous alkali solution, and stirring the mixture to remove the toner component adhered to the carrier surface and the coating resin.
    Type: Grant
    Filed: January 6, 1999
    Date of Patent: October 12, 1999
    Assignee: Powdertech Co., Ltd.
    Inventors: Yuji Sato, Tsuyoshi Itagoshi, Toshio Honjo