Patents by Inventor Kei NIWAYAMA

Kei NIWAYAMA 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).

  • Publication number: 20240393707
    Abstract: A toner contains toner base particles, each containing a binder resin, a release agent, and a charge control agent, and an external additive, wherein the toner base particles have an average circularity of from 0.850 to 0.950, and the external additive contains at least an inorganic particle selected from the group consisting of barium sulfate, magnesium hydroxide, and magnesium oxide, each having an average circularity of from 350 to 1,000 nm.
    Type: Application
    Filed: May 15, 2024
    Publication date: November 28, 2024
    Applicant: Ricoh Company, Ltd.
    Inventors: Kei Niwayama, Masayuki Ishii, Saori Yamada, Shimpei Miyata
  • Publication number: 20230384704
    Abstract: A toner contains mother toner particles each containing a binder resin, a releasing agent, and a charge control agent and an external additive containing hydrophobized polymethylsilsesquioxane particles with an average particle diameter of from 0.050 to 0.150 ?m, wherein the mother toner particles have an average circularity of 0.95 or less.
    Type: Application
    Filed: May 24, 2023
    Publication date: November 30, 2023
    Applicant: Ricoh Company Ltd.
    Inventors: Kei Niwayama, Masayuki Ishii
  • Publication number: 20200319571
    Abstract: An electrophotographic developer is provided. The electrophotographic developer comprises a toner and a carrier. The toner contains alumina particles. The carrier comprises a core particle and a resin layer coating a surface of the core particle. The carrier has a volume average particle diameter (Dv) of from 45 to 70 ?m and a bulk density of from 2.1 to 2.5 g/cm3.
    Type: Application
    Filed: March 31, 2020
    Publication date: October 8, 2020
    Inventors: Kento TAKEUCHI, Yutaka MAKIBE, Kenichi MASHIKO, Masato TAIKOJI, Kei NIWAYAMA
  • Patent number: 10474051
    Abstract: Provided is a carrier for a developer of an electrostatic latent image, the carrier including a core particle, and a resin layer covering the core particle, where the resin layer includes metal compound particles, wherein the metal compound particles include magnesium compound particles or barium compound particles, and an exposed amount B (atomic %) of the magnesium or the barium on a surface of the carrier particle satisfies a relationship below: 10.0?B ?1.2.
    Type: Grant
    Filed: September 14, 2018
    Date of Patent: November 12, 2019
    Assignee: Ricoh Company, Ltd.
    Inventors: Mariko Takii, Koichi Sakata, Tohru Suganuma, Masahiro Seki, Masashi Nagayama, Shinya Nakagawa, Kei Niwayama
  • Patent number: 10254674
    Abstract: A carrier for a developer of an electrostatic latent image, the carrier including: core particles having magnetism; and a coating layer coating a surface of each of the core particles, wherein the coating layer includes two or more kinds of inorganic particles, at least one kind of inorganic particles among the two or more kinds of inorganic particles is inorganic particles A having conductivity and a peak particle diameter of from 300 nm through 1,000 nm, and surface roughness of the carrier calculated by Formula 1 below is from 1.10 m2/g through 1.90 m2/g, C?F??Formula 1 where C is a BET specific surface area (m2/g) of the carrier and F is a BET specific surface area (m2/g) of the core particles.
    Type: Grant
    Filed: October 12, 2017
    Date of Patent: April 9, 2019
    Assignee: Ricoh Company, Ltd.
    Inventors: Masahiro Seki, Hiroyuki Kishida, Haruki Murata, Shinya Nakagawa, Kei Niwayama, Saori Yamada, Kohsuke Miyazaki
  • Publication number: 20190018331
    Abstract: Provided is a carrier for a developer of an electrostatic latent image, the carrier including a core particle, and a resin layer covering the core particle, where the resin layer includes metal compound particles, wherein the metal compound particles include magnesium compound particles or barium compound particles, and an exposed amount B (atomic %) of the magnesium or the barium on a surface of the carrier particle satisfies a relationship below: 10.0?B?1.2.
    Type: Application
    Filed: September 14, 2018
    Publication date: January 17, 2019
    Inventors: Mariko Takii, Koichi Sakata, Tohru Suganuma, Masahiro Seki, Masashi Nagayama, Shinya Nakagawa, Kei Niwayama
  • Patent number: 10031434
    Abstract: A carrier includes a resin layer including Al and Sn and covering the surface of the carrier. A detectable amount of Al is from 1.0% to 12.1% by atom and a ratio (Al/Sn) of the detectable amount of Al to that of Sn is from 2.0 to 50.0 when the carrier is subjected to an X-ray photoelectron spectroscopic (XPS) analysis.
    Type: Grant
    Filed: May 20, 2016
    Date of Patent: July 24, 2018
    Assignee: Ricoh Company, Ltd.
    Inventors: Mariko Takii, Yoshihiro Murasawa, Takahiro Nakamura, Kei Niwayama, Haruki Murata, Masato Taikoji, Koichi Sakata
  • Patent number: 10025214
    Abstract: Carrier for image forming includes a core material particle including a magnetic material and a coating layer disposed on the surface of the core material particle, the coating layer including a resin, carbon black, an inorganic particulate A, and an inorganic particulate B. The carbon black has a concentration gradient along a thickness direction of the coating layer with a concentration from high to low toward a surface of the coating layer while the inorganic particulate A has a concentration gradient along a thickness direction of the coating layer with a concentration from low to high toward the surface of the coating layer. The volume ratio of the carbon black is 0-30 percent at a depth range of 0.0-0.1 ?m from the surface of the coating layer. The inorganic particulate A is electroconductive with a powder specific resistance of 200 ?·cm or less.
    Type: Grant
    Filed: December 28, 2016
    Date of Patent: July 17, 2018
    Assignee: Ricoh Company, Ltd.
    Inventors: Masashi Nagayama, Mariko Takii, Yoshihiro Murasawa, Haruki Murata, Kei Niwayama, Tohru Suganuma, Koichi Sakata, Saori Yamada, Shinya Nakagawa, Kohsuke Miyazaki
  • Publication number: 20180113393
    Abstract: A carrier for a developer of an electrostatic latent image, the carrier including: core particles having magnetism; and a coating layer coating a surface of each of the core particles, wherein the coating layer includes two or more kinds of inorganic particles, at least one kind of inorganic particles among the two or more kinds of inorganic particles is inorganic particles A having conductivity and a peak particle diameter of from 300 nm through 1,000 nm, and surface roughness of the carrier calculated by Formula 1 below is from 1.10 m2/g through 1.90 m2/g, C?F??Formula 1 where C is a BET specific surface area (m2/g) of the carrier and F is a BET specific surface area (m2/g) of the core particles.
    Type: Application
    Filed: October 12, 2017
    Publication date: April 26, 2018
    Inventors: Masahiro SEKI, Hiroyuki Kishida, Haruki Murata, Shinya Nakagawa, Kei Niwayama, Saori Yamada, Kohsuke Miyazaki
  • Publication number: 20170185000
    Abstract: Carrier for image forming includes a core material particle including a magnetic material and a coating layer disposed on the surface of the core material particle, the coating layer including a resin, carbon black, an inorganic particulate A, and an inorganic particulate B. The carbon black has a concentration gradient along a thickness direction of the coating layer with a concentration from high to low toward a surface of the coating layer while the inorganic particulate A has a concentration gradient along a thickness direction of the coating layer with a concentration from low to high toward the surface of the coating layer. The volume ratio of the carbon black is 0-30 percent at a depth range of 0.0-0.1 ?m from the surface of the coating layer. The inorganic particulate A is electroconductive with a powder specific resistance of 200 ?·cm or less.
    Type: Application
    Filed: December 28, 2016
    Publication date: June 29, 2017
    Inventors: Masashi NAGAYAMA, Mariko TAKll, Yoshihiro MURASAWA, Haruki MURATA, Kei NIWAYAMA, Tohru SUGANUMA, Koichi SAKATA, Saori YAMADA, Shinya NAKAGAWA, Kohsuke MIYAZAKI
  • Publication number: 20160363880
    Abstract: A carrier includes a resin layer including Al and Sn and covering the surface of the carrier. A detectable amount of Al is from 1.0% to 12.1% by atom and a ratio (Al/Sn) of the detectable amount of Al to that of Sn is from 2.0 to 50.0 when the carrier is subjected to an X-ray photoelectron spectroscopic (XPS) analysis.
    Type: Application
    Filed: May 20, 2016
    Publication date: December 15, 2016
    Inventors: Mariko TAKII, Yoshihiro MURASAWA, Takahiro NAKAMURA, Kei NIWAYAMA, Haruki MURATA, Masato TAIKOJI, Koichi SAKATA