Patents by Inventor Ichirou Osaki

Ichirou Osaki 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: 5213933
    Abstract: A positively chargeable magnetic toner comprises positively chargeable magnetic toner particles having at least a binder resin, a magnetic substance and a charge controlling agent; wherein the binder resin contains (A) a vinyl polymer having carboxyl groups, acid anhydride groups, partial esters thereof or mixtures of the groups and having and an acid value of 5 to 30, and (B) a copolymer obtained by polymerizing at least a diolefin monomer and a vinyl monomer; and wherein the charge controlling agent contains (C) a quaternary ammonium salt and (D) a nigrosine dye or a triphenylmethane dye, the ratio by weight among the components (A), (B), (C) and (D) being within the range of (A):(B):(C):(D)=80 to 30:70 to 20:2.0 to 0.5: 2.0 to 0.1 relative to 100 parts of the total weight of the components (A) and (B). The present invention also provides an image forming process, an image forming apparatus and a facsimile apparatus, all of which use the positively chargeable magnetic toner.
    Type: Grant
    Filed: May 28, 1991
    Date of Patent: May 25, 1993
    Assignee: Canon Kabushiki Kaisha
    Inventors: Ichirou Osaki, Keita Nozawa, Kuniko Kobayashi, Masatsugu Fujiwara, Masayoshi Shimamura