Patents by Inventor Shigeyuki Hakumoto

Shigeyuki Hakumoto 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: 6020100
    Abstract: A method of producing a color toner whereby a binder resin, a chromatic coloring material and a metal oxide particulate material are mixed to obtain a first mixture. Thereafter, a second mixture is obtained by mixing the first mixture with a material other than the materials used to obtain the first mixture. The second mixture is melted, kneaded, cooled and pulverized.
    Type: Grant
    Filed: March 20, 1998
    Date of Patent: February 1, 2000
    Assignee: Minolta Co., Ltd.
    Inventors: Yoshiaki Iwasaki, Koshiro Nakao, Hiroshi Nakamura, Shigeyuki Hakumoto
  • Patent number: 5547797
    Abstract: The present invention provides a developer for developing electrostatic latent images comprising:a spherical toner whose number average particle size is 2-10 .mu.m and which at least contains a binder resin and a colorant, anda nonspherical toner which comprises practically same composition as that of the spherical toner, has a number average particle size of 2-10 .mu.m, and has the number average particle size within .+-.25% of that of the spherical toner,the spherical toner whose ratio to the total number of toner being 5-80%.The developer the present invention is excellent in fluidity, blade cleaning properties, environmental stability, and charge stability.
    Type: Grant
    Filed: August 2, 1994
    Date of Patent: August 20, 1996
    Assignee: Minolta Co., Ltd.
    Inventors: Masahiro Anno, Minoru Nakamura, Makoto Kobayashi, Shigeyuki Hakumoto
  • Patent number: 4824753
    Abstract: A carrier for use in electrophotographic developers is coated with a hydrocarbon film prepared by plasma polymerization. The film contains at least silicon or fluorine in addition to carbon as a main constituent.
    Type: Grant
    Filed: April 23, 1987
    Date of Patent: April 25, 1989
    Assignee: Minolta Camera Kabushiki Kaisha
    Inventors: Hideo Hotomi, Shigeyuki Hakumoto
  • Patent number: 4262076
    Abstract: A method for manufacturing magnetically attractive toner particles utilized for developing electrostatic latent images includes a first step of thermally kneading a mixture of a first resin material and minute particles of magnetizable material, and a second step of thermally kneading, with a second resin material having a higher softening temperature and/or a physically harder nature being further added at the same time, so that a mixture of these three materials, as a whole, is to constitute a composite material having a specific crushing nature. The composite material thus treated is consequently solidified, and then crushed, to form the toner particles, whereby minute particles of magnetizable material comprising each toner particle are respectively to be exposed from an outer boundary of the toner particle.
    Type: Grant
    Filed: March 1, 1979
    Date of Patent: April 14, 1981
    Assignee: Minolta Camera Kabushiki Kaisha
    Inventors: Shigeyuki Hakumoto, Koji Nagai, Hiromi Kameda