Patents by Inventor Kimitoshi Yamaguchi

Kimitoshi Yamaguchi 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: 6599672
    Abstract: A carrier for an image developer for electrophotography, including core particles, and a coating layer covering each of the core particles, wherein the core particles have a weight average particle diameter of Dv which is 25-45 &mgr;m and a number average particle diameter of Dp which meets with the following condition: 1≦Dv/Dp≦1.3, wherein the core particles have such a particle size distribution that particles having a particle diameter of less than 44 &mgr;m is at least 70% by weight and particles having a particle diameter of less than 22 &mgr;m is not more than 7% by weight.
    Type: Grant
    Filed: August 22, 2002
    Date of Patent: July 29, 2003
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Akihiro Kotsugai
  • Publication number: 20030054279
    Abstract: A carrier for electrophotographic developer essentially consisting of a core material of magnetic particles and thereon provided a resinous coating layer, wherein a weight-average particle-diameter(Dw) of the carrier ranges from 25 to 45 &mgr;m, the content of particles having diameter less than 44 &mgr;m is more than or equal to 75% by weight, the content of particles having diameter more than or equal to 62 &mgr;m is less than one percent by weight, the content of particles having diameter less than 22 &mgr;m is less than or equal to 7.0% by weight, the magnetic moment of the carrier at 1 kilo Oe of magnetic field is more than or equal to 76 emu/g. The carrier shows high optical density of image with no smearing of background area, good reproducibility in developing of small dots in image with no carrier deposition.
    Type: Application
    Filed: May 1, 2002
    Publication date: March 20, 2003
    Inventors: Kimitoshi Yamaguchi, Masahide Yamashita, Akihiro Kotsugai, Hiroaki Takahashi
  • Publication number: 20030044709
    Abstract: A carrier for an image developer for electrophotography, including core particles, and a coating layer covering each of the core particles, wherein the core particles have a weight average particle diameter of Dv which is 25-45 &mgr;m and a number average particle diameter of Dp which meets with the following condition:
    Type: Application
    Filed: August 22, 2002
    Publication date: March 6, 2003
    Inventors: Kimitoshi Yamaguchi, Akihiro Kotsugai
  • Publication number: 20030044713
    Abstract: A method of developing a latent electrostatic image using a two-component developer system, having a ratio (VrNVp) ranges 1.2<(Vr/Vp)<3 where the (Vp) is a linear speed (Vp) [m/sec] of a photosensitive member and the (Vr) is a linear speed (Vr) [m/sec] of a developing sleeve, and applying a biased direct-current (VB) [by volt] wherein; a developing gap(Gp)[cm] as a distance at the nearest point between a photosensitive member and a developing sleeve is less than or equal to 0.6 mm, a ratio(&rgr;p/&rgr;a) satisfies an expression (&rgr;p/&rgr;a)<0.
    Type: Application
    Filed: March 7, 2002
    Publication date: March 6, 2003
    Inventors: Kimitoshi Yamaguchi, Akihiro Kotsugai
  • Patent number: 6489073
    Abstract: Electrostatic latent images are developed with a toner in such a configuration that an electrostatic-latent-image-bearing member is disposed to face a developer-bearing member which bears thereon a developer consisting of a magnetic carrier and a toner by relatively moving the developer-bearing member and the electrostatic-latent-image-bearing member at different velocities, with the development being carried out under conditions represented by formula (1): 0.
    Type: Grant
    Filed: January 12, 2001
    Date of Patent: December 3, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Akihiro Kotsugai, Kimitoshi Yamaguchi, Hiroshi Ikuno
  • Patent number: 6472118
    Abstract: A carrier for an image developer for electrophotography, including core particles, and a coating layer covering each of the core particles, wherein the core particles have a weight average particle diameter of Dv which is 25-45 &mgr;m and a number average particle diameter of Dp which meets with the following condition: 1≦Dv/Dp≦1.3, wherein the core particles have such a particle size distribution that particles having a particle diameter of less than 44 &mgr;m is at least 70% by weight and particles having a particle diameter of less than 22 &mgr;m is not more than 7% by weight.
    Type: Grant
    Filed: November 16, 2000
    Date of Patent: October 29, 2002
    Assignee: Ricoh Company, Ltd
    Inventors: Kimitoshi Yamaguchi, Akihiro Kotsugai
  • Publication number: 20010028987
    Abstract: Electrostatic latent images are developed with a toner in such a configuration that an electrostatic-latent-image-bearing member is disposed to face a developer-bearing member which bears thereon a developer consisting of a magnetic carrier and a toner by relatively moving the developer-bearing member and the electrostatic-latent-image-bearing member at different velocities, with the development being carried out under conditions represented by formula (1): 1 0.
    Type: Application
    Filed: January 12, 2001
    Publication date: October 11, 2001
    Applicant: Ricoh Company, Ltd.
    Inventors: Akihiro Kotsugal, Kimitoshi Yamaguchi, Hiroshi Ikuno
  • Patent number: 5288577
    Abstract: A dry type developer is composed of substantially spherical, electrically insulating toner particles which are free from electroconductive particles, and carrier particles, each carrier particle including a core particle and a resin layer coated on the surface of the core particle, with a resistivity in the range of 10.sup.8 to 10.sup.14 .OMEGA.cm under application of a DC voltage of 1000 volts.
    Type: Grant
    Filed: February 26, 1992
    Date of Patent: February 22, 1994
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Yoichiro Watanabe
  • Patent number: 5102766
    Abstract: A toner for developing latent electronstatic images comprises a coloring agent, a binder resin component and a negative charge controlling agent in an effective amount which is selected from the group consisting of:(i) an aromatic fluoride having formule (I); ##STR1## (ii) an aromatic fluoride having formula (II); ##STR2## (iii) an aromatic fluoride having formula (III); ##STR3## (iv) an aromatic fluoride having formula (IV); and ##STR4## (v) an aromatic fluoride having formula (V). ##STR5## wherein R.sup.1 to R.sup.8, R.sup.f1 and R.sup.f2, n, X and Y are the same as previously defined in the specification.
    Type: Grant
    Filed: March 20, 1990
    Date of Patent: April 7, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshiki Nanya, Kimitoshi Yamaguchi, Hiromitsu Kawase, Makoto Ookawara
  • Patent number: 5085965
    Abstract: A negatively chargeable toner for developing latent electrostatic images comprising a coloring agent, a resin component which comprises a homopolymer of a first monomer having formula (I) or a copolymer of the aforementioned first monomer and a second monomer: ##STR1## wherein R.sup.1 represents --H or --CH.sub.3 ; R.sup.2 and R.sup.3 each represent --CN, --COOH or --NO.sub.2 ; R.sup.4 represents --F, --Cl or --Br; and n is an integer of 1 to 10.
    Type: Grant
    Filed: March 20, 1990
    Date of Patent: February 4, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshiki Nanya, Kimitoshi Yamaguchi, Kazuo Tsubuko, Toshihiko Takahashi, Hiromitsu Kawase, Makoto Ookawara
  • Patent number: 5079123
    Abstract: A dry-type toner for electrophotography comprising a binder resin, a coloring agent, and, as a lubricant, a carnauba wax substantially free of free aliphatic acids. The toner may further comprise a magnetic material, and the resulting toner mixture can be used as a magnetic toner.
    Type: Grant
    Filed: May 30, 1990
    Date of Patent: January 7, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshiki Nanya, Kimitoshi Yamaguchi, Hiromitsu Kawase
  • Patent number: 4990425
    Abstract: A dry-type toner is disclosed, which comprises as the main components a resin, a coloring agent and a negative charge controlling agent selected from the group consisting of (1) metallic salts of indolecarboxylic acid having the general formula (I); ##STR1## (2) metallic salts of quinolinecarboxylic acid having the general formula (II); ##STR2## and (3) metallic salts of benzothiazole derivatives having the general formula (III): ##STR3##
    Type: Grant
    Filed: April 5, 1989
    Date of Patent: February 5, 1991
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshiki Nanya, Kimitoshi Yamaguchi
  • 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
  • Patent number: 4670368
    Abstract: A developer comprises a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles, having an electric resistivity of 10.sup.12 .OMEGA.cm or more, and (b) electroconductive magnetic particles having an electric resistivity of 10.sup.9 .OMEGA.cm or less, a smaller volume mean diameter than that of the magnetic toner particles, with the saturation magnetic moment of the electroconductive magnetic particles being in the range of from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of the magnetic toner particles.
    Type: Grant
    Filed: January 30, 1986
    Date of Patent: June 2, 1987
    Assignee: Ricoh Company, Ltd.
    Inventors: Hachiro Tosaka, Kimitoshi Yamaguchi, Motoi Orihara
  • Patent number: 4590141
    Abstract: Carrier particles are disclosed for use in a two-component dry-type developer for developing latent electrostatic images to visible images, for use in electrophotography, electrostatic recording methods and electrostatic printing methods, which carrier particles are coated with a silicone resin coating layer having high resistance to abrasion and the so-called "spent phenomenon" while in use, and which therefore can be used repeatedly for a long period of time, yielding developed images with high quality. The high resistance to abrasion of the silicone resin coating layer is attained by adding to the silicone coating layer, as an inorganic fortifying agent against abrasion, silicon carbide or potassium titanate.
    Type: Grant
    Filed: October 19, 1984
    Date of Patent: May 20, 1986
    Assignee: Ricoh Company
    Inventors: Mitsuo Aoki, Satoru Inoue, Kimitoshi Yamaguchi, Mitsuru Uchida, Masami Tomita, Chiaki Uematsu
  • Patent number: 4562136
    Abstract: A two-component dry-type developer which comprises carrier particles coated with silicone resin and toner particles containing as a negative polarity control agent a monoazo metal complex dye. As the monoazo metal complex dye, the following metal complex dye is preferable for use in this two-component dry-type developer: ##STR1## wherein X, Y and Z independently represent hydrogen, halogen, a carboxyl group, a hydroxyl group, a nitro group, a sulfo group or a sulfonamide group; and A.sup.+ represents H.sup.+, K.sup.+, Na.sup.+ or an aliphatic ammonium cation.
    Type: Grant
    Filed: November 7, 1984
    Date of Patent: December 31, 1985
    Assignee: Ricoh Company, Ltd.
    Inventors: Satoru Inoue, Mitsuru Uchida, Kimitoshi Yamaguchi, Mitsuo Aoki, Masami Tomita, Chiaki Uematsu