Patents by Inventor Ryoichi Fujita

Ryoichi Fujita 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: 5512402
    Abstract: A carrier for electrophotography has carrier particles. The carrier has a 50% average particle diameter (D.sub.50) of from 15 .mu.m to 45 .mu.m and contains from 1% to 20% of carrier particles with a size smaller than 22 .mu.m, not more than 3% of carrier particles with a size smaller than 16 .mu.m, from 2% to 15% of carrier particles with a size of 62 .mu.m or larger, and not more than 2% of carrier particles with a size of 88 .mu.m or larger. The carrier has a specific surface area S.sub.1 as measured by an air-permeability method and a specific surface area S.sub.2 as calculated by the following expression:S.sub.2 =(6/.rho..D.sub.50).times.10.sup.4wherein .rho. is a specific gravity of carrier; satisfying the following condition:1.2.ltoreq.S.sub.1 /S.sub.2 .ltoreq.2.0.
    Type: Grant
    Filed: May 19, 1994
    Date of Patent: April 30, 1996
    Assignee: Canon Kabushiki Kaisha
    Inventors: Kenji Okado, Toshiyuki Ugai, Ryoichi Fujita, Makoto Kanbayashi, Tsuyoshi Takiguchi, Yasuhiro Ichikawa, Wakashi Iida
  • Patent number: 5418102
    Abstract: A developer for developing an electrostatic image has a toner containing a binder resin and a colorant. The binder resin is comprised of an AB-type block copolymer having segment-A and segment-B.The segment-A has a copolymer structure comprised of a styrene monomer and at least one monomer selected from the group consisting of an acrylic monomer, a methacrylic monomer and a diene monomer, and the segment-B has a copolymer structure comprised of a styrene monomer and at least one monomer selected from the group consisting of an acrylic monomer, a methacrylic monomer and a diene monomer, provided that the segment-A and segment-B have copolymer structures different from each other.
    Type: Grant
    Filed: November 27, 1991
    Date of Patent: May 23, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Takaaki Kotaki, Yoshihiko Hyosu, Ryoichi Fujita, Makoto Kanbayashi, Minoru Shimojo