Patents by Inventor Tomoyasu Umeno

Tomoyasu Umeno 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: 6051352
    Abstract: A carrier for developing an electrostatic latent image is disclosed. The carrier comprises a magnetite core and a resin coated on the magnetite core wherein the magnetite core contains FeO and Fe.sub.2 O.sub.3, the mole ratio of FeO/Fe.sub.2 O.sub.3 being 0.15/1.0 to 0.7/1.0, and the carrier contains a magnesium atom containing material at a surface of the carrier, magnesium atom content ratio at the surface being 1.5 to 5.0 (percent in the number of atoms).A developer for developing an electrostatic latent image using the carrier and a developing method using the carrier or the developer is also disclosed.
    Type: Grant
    Filed: September 4, 1998
    Date of Patent: April 18, 2000
    Assignee: Konica Corporation
    Inventors: Tomoyasu Umeno, Ryuji Kitani, Tatsuya Nagase, Meizo Shirose
  • Patent number: 5932388
    Abstract: A carrier for a developer developing an electrostatic image is disclosed. The carrier contains magnesium from 2.0 to 25.0 by means of number of atoms by percent in surface portion. According to the invention excellent charge rising properties may be consistently exhibited for extended time periods, and neither toner scattering nor background deposits on images are caused.
    Type: Grant
    Filed: October 28, 1997
    Date of Patent: August 3, 1999
    Assignee: Konica Corporation
    Inventors: Tomoyasu Umeno, Meizo Shirose, Tatsuya Nagase, Ryuji Kitani
  • Patent number: 5733692
    Abstract: Disclosed is a toner kit for an electrophotography, comprising a black toner and a first toner whose color is other than black, whereinsaid first toner has a first softening point T.sub.1, said first toner comprises a first releasing agent, a first intermolecular crosslinked polyester resin having a second softening point T.sub.2 of 100.degree. C. to 150.degree. C., obtained by a reaction of an alcohol having at least two hydroxyl group and an aromatic carboxylic acid having at least two carboxyl group and a processed pigment having a third softening point T.sub.3 of 100.degree. C. to 150.degree. C., said processed pigment comprising a pigment and a resin in which said pigment is dispersed, and said resin forms domain structure in said first polyester resin, andwherein said black toner has a fourth softening point T.sub.4, said black toner comprises a second releasing agent, a colorant and a second intermolecular crosslinked polyester resin having a fifth softening point T.sub.5 of 100.degree. C. to 150.
    Type: Grant
    Filed: March 26, 1997
    Date of Patent: March 31, 1998
    Assignee: Konica Corporation
    Inventors: Tatsuya Nagase, Tomoyasu Umeno, Ryuji Kitani, Meizo Shirose
  • Patent number: 5376488
    Abstract: A carrier of developer for developing an electrostatic image and a method for producing the carrier are disclosed. The carrier comprises core particles each having a resin layer covering the surface of said core particle. The resin layer is formed by dry process in which the core particles are stirred together with fine resin particles with no solvent for the resin to form the resin layer on the surface of each core particle. The fine resin particles comprise a homopolymer or a copolymer comprising a fluorinated acrylate repeating unit and are formed by emulsified polymerization carried out in the presence of a surfactant comprising an alkylbenzene sulfonic compound, and the residual amount of the surfactant in the fine resin particles is within the range of from 60 ppm to 10,000 ppm. The carrier is improved in adhesion between the surface of the core and the resin layer and satisfactory in friction electricity providing capability.
    Type: Grant
    Filed: April 26, 1993
    Date of Patent: December 27, 1994
    Assignee: Konica Corporation
    Inventors: Ken Ohmura, Shigenori Kouno, Tomoyasu Umeno