Patents by Inventor Koichi Oyamada

Koichi Oyamada 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).

  • Electrophotographic toner
    Patent number: 5252421
    Abstract: An electrophotographic is disclosed, comprising a binder resin, a coloring material, and a polyalkylene, wherein the polyalkylene has an average particle volume of 0.05 .mu.m.sup.3 or more. The toner exhibits broadened fixing latitude when fixed by heat roll fixing without using any offset inhibiting liquid.
    Type: Grant
    Filed: February 13, 1991
    Date of Patent: October 12, 1993
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Masanori Ichimura, Toru Murakami, Koichi Oyamada
  • Electrophotographic red toner
    Patent number: 5032483
    Abstract: A red color toner for electrophotography comprising a binder resin and a colorant component comprising C.I. Pigment Red 48:1, or C.I. Pigment Red 48:1 and a second red pigment which may be C.I. Pigment Red 122 or C.I. Pigment Red 57:1, or C.I. Pigment Red 48:1 and a yellow pigment which may be C.I. Pigment Yellow 97 or C.I. Pigment Yellow 12. The colorant preferably is present in an amount between about 1% and about 20% by weight of the binder resin.
    Type: Grant
    Filed: November 22, 1989
    Date of Patent: July 16, 1991
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Masanori Ichimura, Toru Murakami, Koichi Oyamada
  • Electrophotographic developer containing tin oxide
    Patent number: 4965162
    Abstract: An electrophotographic developer is disclosed, that contains toner particles and fine particles of tin oxide having an electrical resistivity of from 10.sup.2 to 10.sup.9 .OMEGA..cm. The developer ensures efficient image transfer and exhibits good developing ability.
    Type: Grant
    Filed: September 5, 1989
    Date of Patent: October 23, 1990
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Shigeo Aonuma, Koichi Oyamada
  • Electrophotographic developer
    Patent number: 4933251
    Abstract: An electrophotographic developer is described, comprising toner particles and carrier particles, characterized in that the toner particles have a layer of externally additive agents comprising fine metal oxide particles having an electric resistance of 1.times.10.sup.2 to 1.times.10.sup.9 .OMEGA..multidot.cm and fine silica particles and cleaning aid particles, and the layer of externally additive agents does not have a chain like structure.
    Type: Grant
    Filed: August 4, 1988
    Date of Patent: June 12, 1990
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Masanori Ichimura, Toru Murakami, Koichi Oyamada
  • Two component electrophotographic developer
    Patent number: 4880719
    Abstract: An electrophotographic two-component system developer is described, comprising a positive charging toner and a negative charging carrier of the dispersed magnetic powder type, wherein a hydrophilic alumina particle is adhered onto the surface of said positive charging toner and a negative charging carrier has a volume average particle diameter of from 30 to 80 .mu.m. The developer provides reduced toner cloud upon development processing and provides toner images free from fog.
    Type: Grant
    Filed: June 29, 1988
    Date of Patent: November 14, 1989
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Toshiaki Murofushi, Hiroshi Nakazawa, Koichi Oyamada, Shigeo Aonuma, Yoshimi Amagai, Yasuhiro Ohya
  • Electrophotographic developer containing positively chargeable toner
    Patent number: 4837100
    Abstract: A positively chargeable electrophotographic developer is disclosed, comprising a carrier, toner particles positively chargeable by friction with the carrier, fine particles of hydrophilic alumina, and fine particles of one of tin oxide, hydrophobic silica and titanium dioxide. The developer hardly undergoes toner cloud or toner dropping during development and suffers neither extreme deterioration in charging properties nor fog formation even when used for taking a large number of copies.
    Type: Grant
    Filed: September 29, 1987
    Date of Patent: June 6, 1989
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Toshiaki Murofushi, Yasuhiro Ohya, Hiroshi Nakazawa, Koichi Oyamada