Patents by Inventor Tomomi HARASHIMA

Tomomi HARASHIMA 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: 12078961
    Abstract: A toner includes a crystalline polyester resin and an amorphous polyester resin. A ratio of the storage modulus of the toner G? (To) at a temperature To to the storage modulus of the toner G? (To+3) at a temperature To+3 is greater than or equal to 10, in a case where the temperature To is within a range from 50° C. to 65° C.
    Type: Grant
    Filed: August 20, 2021
    Date of Patent: September 3, 2024
    Assignee: Ricoh Company, Ltd.
    Inventors: Yuka Mizoguchi, Hiroshi Yamashita, Junichi Watanabe, Tomomi Harashima
  • Publication number: 20230014605
    Abstract: A toner includes toner base particles and external additives deposited on a surface of the toner base particle. The toner base particle includes an amorphous polyester resin, a crystalline polyester resin, a release agent, and resin particles. An abundance ratio of the crystalline polyester resin in the surface of the toner base particle as observed by TEM is 2.5% or greater but 25% or less. The resin particles are deposited at the surface of the toner base particle as observed by SEM. A ratio of aggregates of the resin particles occupying the surface of the toner base particle is 1% or greater but 70% or less, where R is a major axis of the minimum particle of the resin particles, and the resin particle having a major axis of 3R or greater is determined as the aggregate.
    Type: Application
    Filed: July 6, 2022
    Publication date: January 19, 2023
    Applicant: Ricoh Company, Ltd.
    Inventors: Akinori SAITOH, Akio Takei, Toma Takebayashi, Masahiro Yukikawa, Tomomi Harashima, Hiroshi Yamada
  • Publication number: 20220197165
    Abstract: Provided is a toner including toner base particles. Each toner base particle includes a crosslinked component. The crosslinked component includes a nonlinear polymer having 3 or more branches, terminals of which are metal ion crosslinked, and a glass transition temperature Tg of the nonlinear polymer as measured by differential scanning calorimetry is ?60° C. or higher but lower than 0° C.
    Type: Application
    Filed: December 21, 2021
    Publication date: June 23, 2022
    Applicant: Ricoh Company, Ltd.
    Inventors: Tomomi Harashima, Junichi Watanabe, Hiroshi Yamashita, Shinya Nakayama
  • Publication number: 20220057726
    Abstract: A toner includes a crystalline polyester resin and an amorphous polyester resin. A ratio of the storage modulus of the toner G? (TO) at a temperature TO to the storage modulus of the toner G? (TO+3) at a temperature TO+3 is greater than or equal to 10, in a case where the temperature TO is within a range from 50° C. to 65° C.
    Type: Application
    Filed: August 20, 2021
    Publication date: February 24, 2022
    Applicant: Ricoh Company, Ltd.
    Inventors: Yuka Mizoguchi, Hiroshi Yamashita, Junichi Watanabe, Tomomi Harashima
  • Patent number: 11061343
    Abstract: A toner including: a plate-shaped pigment containing a metal as a main component; and a binder resin containing polyester resin (A) that is insoluble in THF, wherein: a weight average molecular weight (Mw) of a tetrahydrofuran (THF)-soluble component of the toner as determined by gel permeation chromatography (GPC) is 5,000 or higher but 14,000 or lower; and a glass transition temperature (Tg) of a THF-insoluble component of the toner as determined from a differential scanning colorimetry (DSC) curve at first heating in DSC is ?60° C. or higher but 10° C. or lower.
    Type: Grant
    Filed: February 18, 2020
    Date of Patent: July 13, 2021
    Assignee: Ricoh Company, Ltd.
    Inventors: Yuka Mizoguchi, Ryota Inoue, Hiroshi Yamashita, Minoru Masuda, Daichi Hisakuni, Tomomi Harashima
  • Patent number: 10895816
    Abstract: An image forming apparatus is provided that includes: first and second electrostatic latent image bearers; first and second electrostatic latent image forming devices; first and second developing devices configured to develop first and second electrostatic latent images with a colored toner and a special-color toner to form a colored toner image and a special-color toner image, respectively; a primary transfer device configured to transfer the colored toner image and the special-color toner image onto an intermediate image bearer in an overlapping manner to form a composite toner image; a secondary transfer device configured to transfer the composite toner image onto a recording medium; and a fixing device configured to fix the composite toner image thereon. The special-color toner comprises plate-like and/or film-like pigments. An absolute difference in volume resistivity between the special-color toner and the colored toner is 0.30 log ? cm or less.
    Type: Grant
    Filed: September 12, 2019
    Date of Patent: January 19, 2021
    Assignee: Ricoh Company, Ltd.
    Inventors: Minoru Masuda, Hiroshi Yamashita, Ryota Inoue, Yuka Mizoguchi, Daichi Hisakuni, Tomomi Harashima
  • Publication number: 20200285167
    Abstract: A toner including: a plate-shaped pigment containing a metal as a main component; and a binder resin containing polyester resin (A) that is insoluble in THF, wherein: a weight average molecular weight (Mw) of a tetrahydrofuran (THF)-soluble component of the toner as determined by gel permeation chromatography (GPC) is 5,000 or higher but 14,000 or lower; and a glass transition temperature (Tg) of a THF-insoluble component of the toner as determined from a differential scanning colorimetry (DSC) curve at first heating in DSC is ?60° C. or higher but 10° C. or lower.
    Type: Application
    Filed: February 18, 2020
    Publication date: September 10, 2020
    Inventors: Yuka MIZOGUCHI, Ryota INOUE, Hiroshi YAMASHITA, Minoru MASUDA, Daichi HISAKUNI, Tomomi HARASHIMA
  • Publication number: 20200089140
    Abstract: An image forming apparatus is provided that includes: first and second electrostatic latent image bearers; first and second electrostatic latent image forming devices; first and second developing devices configured to develop first and second electrostatic latent images with a colored toner and a special-color toner to form a colored toner image and a special-color toner image, respectively; a primary transfer device configured to transfer the colored toner image and the special-color toner image onto an intermediate image bearer in an overlapping manner to form a composite toner image; a secondary transfer device configured to transfer the composite toner image onto a recording medium; and a fixing device configured to fix the composite toner image thereon. The special-color toner comprises plate-like and/or film-like pigments. An absolute difference in volume resistivity between the special-color toner and the colored toner is 0.30 log ? cm or less.
    Type: Application
    Filed: September 12, 2019
    Publication date: March 19, 2020
    Inventors: Minoru MASUDA, Hiroshi YAMASHITA, Ryota INOUE, Yuka MIZOGUCHI, Daichi HISAKUNI, Tomomi HARASHIMA