Patents by Inventor Kazuhiko Umemura

Kazuhiko Umemura 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).

  • Publication number: 20030186154
    Abstract: A carrier for electrophotographic developer comprising carrier particles, each carrier particle having at least one surface-coating layer by resin material, wherein the surface-coating layer containing an acrylic resin and a silicone resin, the acrylic resin is in an amount ranging 10 to 90 wt. % based on the total amount of resin coating ingredients. The carrier shows no accumulation of toner-spents, therefore can obtain a stable electric charge, and has no layer scraping in binder resin layer, therefore can obtain a stable electric resistance, hence occurs no deterioration of images reproduced, by using acrylic resin having high anti-abrasive and high surface energy, whereas it has strong adhesiveness and high fragility, in combination use of silicone resin having poor anti-abrasive and small adhesiveness but has low fragility, thus is hard to cause a toner spent and hard to integrate the spent constituents due to its low surface energy.
    Type: Application
    Filed: May 24, 2002
    Publication date: October 2, 2003
    Inventors: Kousuke Suzuki, Satoshi Mochizuki, Yasuo Asahina, Kazuhiko Umemura, Hideki Sugiura, Minoru Masuda, Tomomi Tamura
  • Publication number: 20030152857
    Abstract: A toner for electrophotography contains a binder resin and a colorant, the toner for electrophotography has a tensile fracture strength of 10-1400 (N/m2) under 10 kg/cm2 compression, and a loose apparent density of 0.10-0.50 (g/cm3).
    Type: Application
    Filed: August 7, 2002
    Publication date: August 14, 2003
    Inventors: Hideki Sugiura, Satoshi Mochizuki, Kazuhiko Umemura, Yasuo Asahina, Minoru Masuda, Kohsuke Suzuki, Tomomi Tamura, Yasuaki Iwamoto
  • Patent number: 6493529
    Abstract: A charging device which charges a body to be charged. At least a pair of linear electrodes is provided on a substrate so as to be close to each other. Walls are provided near the linear electrodes. Each of the walls has a height larger than a line width of each of the linear electrodes. The linear electrodes are surrounded by the walls and the substrate. The charging device alternatively includes a plurality of dielectrics and electrodes disposed along a first direction facing a drum so that the plurality of dielectrics sandwich the plurality of electrodes along a second direction perpendicular to the first direction, the dielectrics have a height larger than a height of the electrodes along the first direction, and at least two neighboring electrodes have different shapes.
    Type: Grant
    Filed: July 3, 2000
    Date of Patent: December 10, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuhiko Umemura, Tomoaki Sugawara, Tatsuya Sato, Hiroshi Kondo, Shohji Tanaka
  • Publication number: 20020182526
    Abstract: A toner including a binder resin, a colorant, and a product of an iron compound containing an aromatic hydroxylcarboxylic acid as a ligand and represented by the formula (I) described in the specification, wherein the product has such a characteristic that a filtrate obtained by filtering a dispersion of 10 g of the product dispersed in 200 ml of purified water provides an electric conductivity of not greater than 600 &mgr;S/cm.
    Type: Application
    Filed: March 28, 2002
    Publication date: December 5, 2002
    Inventors: Minoru Masuda, Satoshi Mochizuki, Yasuo Asahina, Kazuhiko Umemura, Hideki Sugiura, Kohsuke Suzuki, Tomomi Tamura
  • Publication number: 20020160290
    Abstract: A toner for electrostatic image development in which the weight concentration of polar-solvent-soluble material is 1000 &mgr;g or less, based on the toner, and an image forming method comprising a step of forming a toner image by developing a latent electrostatic image by using the toner for electrostatic image development.
    Type: Application
    Filed: January 31, 2002
    Publication date: October 31, 2002
    Inventors: Hideki Sugiura, Satoshi Mochizuki, Yasuo Asahina, Kazuhiko Umemura, Minoru Masuda, Kohsuke Suzuki, Tomomi Tamura
  • Publication number: 20020155366
    Abstract: A dry toner for developing electrostatic images, including a colorant and a binder resin which comprises a copolymer resin having (A) a polyol resin moiety having a main chain of polyoxyalkylene and obtained by reaction of (a) an epoxy resin, (b) a dihydric phenol, and (c) an alkylene oxide adduct of a dihydric phenol or a glycidyl ether thereof; and (B) a polyester resin moiety obtained by reacting an alkylene oxide adduct of a dihydric phenol or a glycidyl ether thereof with a polycarboxylic acid, wherein the weight ratio of the epoxy resin of the polyol resin moiety (A) to the polyester resin moiety (B) is 95:5 to 60:40, wherein the epoxy resin includes at least two kinds of bisphenol epoxy resins having different number-average molecular weights, and wherein the binder resin has an acid value of not greater than 5.
    Type: Application
    Filed: January 31, 2002
    Publication date: October 24, 2002
    Inventors: Satoshi Mochizuki, Hideki Sugiura, Kazuhiko Umemura, Minoru Masuda, Kohsuke Suzuki, Tomomi Suzuki, Yasuo Asahina
  • Patent number: 6447973
    Abstract: A liquid developer containing a carrier liquid containing silicone oil, and toner particles dispersed in the carrier liquid and each containing a coloring agent and a resin, the resin contains at least one member selected from the group consisting of the following resins (a)-(g): (a): rosin polymers having a softening point of 50-190° C., a glass transition point of 10-170° C. and a molecular weight of 2,000-40,000 and obtained by reacting (a1) a rosin glycidyl ester, (a2) dicarboxylic acid or dicarboxylic anhydride, (a3) at least one crosslinking agent selected from the group consisting of polyfunctional epoxy compounds, tri- or more polybasic acids or anhydrides thereof tri- or more polyhydric alcohols, and (a4) a dihydric alcohol; (b): vinyl polymers having a ratio of the weight average molecular weight to the number average molecular weight of greater than 4; (c): olefin resins having a melt index of 2.5-700; (d): polyolefins or polyolefin copolymers having an acid value of 0.
    Type: Grant
    Filed: August 23, 2000
    Date of Patent: September 10, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Tsuyoshi Asami, Kazuo Tsubuko, Aiko Ishikawa, Akihiro Koseki, Takeo Kudoh, Kazuhiko Umemura
  • Patent number: 5952048
    Abstract: An ink composition contains a carrier medium and charged particles containing a coloring agent, which ink composition satisfies at least one condition of condition A or B: condition A that the specific charge quantity of the charged particles is in a range of 10 to 1,000 .mu.C/g with a positive or negative polarity; and condition B that the specific resistance of the ink composition is 10.sup.10 .OMEGA.cm or more; and ink-jet recording methods using the ink composition are proposed.
    Type: Grant
    Filed: July 22, 1997
    Date of Patent: September 14, 1999
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuo Tsubuko, Nobutaka Kinoshita, Tsuyoshi Asami, Akihiko Gotoh, Kazuhiko Umemura, Kazuyo Mizuno, Makoto Okawara
  • Patent number: 5759733
    Abstract: A liquid developer for use in electrophotography is disclosed, which comprises (i) a toner comprising as the main toner components a colorant, a resin, and a polyolefin resin having an acid value of from 5 to 50 and a melt viscosity at 200.degree. C. of from 100 to 15,000 cps, and (ii) a carrier liquid in which the toner is dispersed. The polyolefin resin and the colorant in the liquid developer may constitute an integral flushing colorant which is prepared by subjecting the resin and the colorant to flushing processing.
    Type: Grant
    Filed: January 13, 1992
    Date of Patent: June 2, 1998
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuo Tsubuko, Shinichi Kuramoto, Toshiki Nanya, Kazuhiko Umemura, Kayoko Nagai
  • Patent number: 5740507
    Abstract: A toner container densely packed with toner to be replenished into a developing unit included in an image forming apparatus, and a method of producing the same. The toner is packed in the container with a ratio of a packing density to a saturation bulk density greater than 1.0, a mean penetration greater than 5.0 mm inclusive, and a standard deviation of penetration not exceeding one-fifth of the mean penetration. The toner can be smoothly and continuously replenished into the developing unit so as to form a number of images matching the amount thereof.
    Type: Grant
    Filed: April 4, 1996
    Date of Patent: April 14, 1998
    Assignee: Ricoh Company, Ltd.
    Inventors: Hideo Ichikawa, Sunao Ikeda, Nobuhiro Makita, Michiharu Narushima, Seiji Terazawa, Masakazu Nakada, Kazuhiko Umemura
  • Patent number: 5328794
    Abstract: A fluorine-containing graft copolymer prepared by a step (i) of polymerizing a monomer having formula (I) and an unsaturated carboxylic acid or a monomer having a glycidyl group to obtain a copolymer, ##STR1## wherein R represents --H or --CH.sub.3 group; and A represents --COOC.sub.n H.sub.2n+1 or OC.sub.n H.sub.2n+1, in which n is an integer of 6 to 20; a step (ii) of esterifying the resulting copolymer by using a monomer having a glycidyl group in the case where a constituting monomer of the above copolymer is an unsaturated carboxylic acid, or by using an unsaturated carboxylic acid in the case where a constituting monomer of the above copolymer is a monomer having a glycidyl group; and a step (iii) of graft-polymerizing a monomer comprising at least fluoroalkyl acrylate or fluoroalkyl methacrylate on the above esterified copolymer. In addition, a toner comprising a coloring agent and a resin component which comprises the above-mentioned fluorine-containing graft copolymer is disclosed.
    Type: Grant
    Filed: March 16, 1993
    Date of Patent: July 12, 1994
    Assignee: Ricoh Company, Ltd.
    Inventors: Tsubuko Kazuo, Shinichi Kuramoto, Kazuhiko Umemura, Toshihiko Takahashi, Hidemi Uematsu
  • Patent number: 5189102
    Abstract: A method for producing a vinyl resin comprising the steps of dissolving or dispersing a polymerizable vinyl monomer in a polymerization solvent containing a silicone oil, and polymerizing the polymerizable vinyl monomer in the presence of a polymerization catalyst.
    Type: Grant
    Filed: March 4, 1992
    Date of Patent: February 23, 1993
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuo Tsubuko, Shinichi Kuramoto, Kazuhiko Umemura, Hidemi Uematsu, Okawara, Makoto
  • Patent number: 5169739
    Abstract: A liquid developer comprises an aliphatic hydrocarbon carrier liquid and a toner dispersed in the carrier liquid, which toner comprises a coloring agent and a resin component, wherein a solid toner component which is obtained by evaporating the liquid developer to dryness has a softening point of 60.degree. C. to 90.degree. C. and flow-initiating point of 110.degree. C. to 160.degree. C.
    Type: Grant
    Filed: February 13, 1990
    Date of Patent: December 8, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuhiko Umemura, Kazuo Tsubuko, Shinichi Kuramoto, Toshihiko Takahashi, Hidemi Uematsu
  • Patent number: 5061587
    Abstract: A toner for developing latent electrostatic images comprising a coloring agent and a fluorine-contained graft copolymer which is prepared by grafting a fluorine-contained monomer to a main polymer comprising a repeating unit represented by formula (I): ##STR1## wherein R and R' each independently represent H or CH.sub.3, and m represent san integer of 1 to 20.
    Type: Grant
    Filed: October 13, 1989
    Date of Patent: October 29, 1991
    Assignee: Ricoh Company Ltd.
    Inventors: Kazuo Tsubuko, Shinichi Kuramoto, Kazuhiko Umemura, Hidemi Uematsu
  • Patent number: 5026621
    Abstract: A toner for electrophotography is disclosed, which comprises as the main components a coloring component and a binder resin which is a block copolymer comprising a functional segment (A) consisting of at least one of a fluoralkyl acryl ester block unit or a fluoralkyl methacryl ester block unit, and a compatible segment (B) consisting of a fluorine-free vinyl or olefin monomer block unit.
    Type: Grant
    Filed: May 12, 1989
    Date of Patent: June 25, 1991
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuo Tsubuko, Shinichi Kuramoto, Kazuhiko Umemura, Makoto Ohkawara
  • Patent number: 4950573
    Abstract: A toner for developing latent electrostatic images is disclosed, which comprises (a) thermofusible base particles A having a softening point of 80.degree. C. or less, a flow starting temperature of 110.degree. C. or less, and an average particle size of 5 to 25 .mu.m, and (b) small particles B comprising as the main component an organic polymeric material having a softening point at least 5.degree. C. higher than the softening point of the base particles A and no practical softening point, and an average particle size ranging from 0.1 .mu.m or more, but not more than 1/4 of the average particle size of the base particles A, which small particles B are embedded in the surface of the base particles A so as to cover the surface of the base particles A to a depth of less than the particle size of the small particles B.
    Type: Grant
    Filed: November 17, 1987
    Date of Patent: August 21, 1990
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Kazuhiko Umemura, Yoshihiro Nomura