Patents by Inventor Yasuaki Iwamoto

Yasuaki Iwamoto 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: 20010006197
    Abstract: A two-step process for the production of a toner for developing electrostatic images, including a first pulverizing step wherein a toner composition containing a binder and a coloring agent is pulverized to obtain preliminarily pulverized particles having a weight average particle diameter of 20-100 &mgr;m and containing no more than 50% by weight of particles having roundness of 0.90 or less, and a second pulverizing step wherein the preliminarily pulverized particles are finely pulverized to obtain finely pulverized particles having a weight average particle diameter of 5-13 &mgr;m and containing no more than 30% by weight of particles having roundness of 0.90 or less and no more than 15%, based on the total number of particles of the finely pulverized particles, of particles having a particle diameter of 5 &mgr;m or less.
    Type: Application
    Filed: December 21, 2000
    Publication date: July 5, 2001
    Applicant: RICOH COMPANY, LTD.
    Inventors: Nobuyasu Makino, Tomotsugu Miyamoto, Mitsuyoshi Izu, Ryoichi Ito, Yasuaki Iwamoto, Kazuyuki Yazaki
  • Patent number: 6183926
    Abstract: A toner is made or toner particles which contains a binder resin and a coloring agent, wherein the toner particles have a weight-average particle size in a range of 6.0 to 11.5 &mgr;m, and contains toner particles (a) with a particle diameter of 5 &mgr;m or less in a content ratio of 1 to 15% by number, and toner particles (b) with a particle diameter of twice or more the weight-average particle size in a content ratio of 5 wt % or less, and the number-average particle size D25 and the number-average particle size D75 respectively obtained when the cumulative number of the toner particles reaches 25% and 75% at the measurement of a cumulative toner particle distribution by number thereof are in the relationship of 0.60≦D25/D75≦0.95. A two-component developer includes the above-mentioned toner and a carrier.
    Type: Grant
    Filed: October 25, 1999
    Date of Patent: February 6, 2001
    Assignee: Ricoh Company, Ltd.
    Inventors: Noboru Kuroda, Yasushi Nakamura, Ryoichi Ito, Yasuaki Iwamoto, Kohki Katoh, Tomio Kondou, Kenichi Uehara, Yoshihiro Sugiyama, Yasuyuki Sanui
  • Patent number: 5840456
    Abstract: A color toner includes a binder resin composition comprising a binder resin A with a softening point in the range of 85.degree. to 110.degree. C., and a binder resin B with a softening point in the range of 115.degree. to 135.degree. C., with the binder resin A and the binder resin B being compatible with each other; a coloring agent; and a wax with a melting point in the range of 65.degree. to 90.degree. C., which is not compatible with the binder resin composition and dispersed in the binder resin composition.
    Type: Grant
    Filed: August 8, 1996
    Date of Patent: November 24, 1998
    Assignee: Ricoh Company, Ltd.
    Inventors: Masami Tomita, Hiroshi Yaguchi, Yasuo Asahina, Yasuaki Iwamoto, Satoru Miyamoto, Tomomi Suzuki
  • Patent number: 5514511
    Abstract: A toner for developing latent electrostatic images including a coloring agent, and a binder resin composition having resin particles, each resin particle having a matrix and domain particles with an average particle diameter of 0.5 to 2.0 .mu.m dispersed in the matrix; with the toner having such rheological characteristics that the storage elastic modulus (G') thereof at 80.degree. to 100.degree. C. under a frequency of 100 Hz is in the range of 5.times.10.sup.6 to 5.times.10.sup.7 dyne/cm.sup.2, and the loss elastic modulus (G") thereof at 200.degree. to 220.degree. C. under a frequency of 100 Hz is in the range of 1.times.10.sup.3 to 1.times.10.sup.5 dyne/cm.sup.2.
    Type: Grant
    Filed: July 12, 1994
    Date of Patent: May 7, 1996
    Assignee: Ricoh Company, Ltd.
    Inventors: Yasuaki Iwamoto, Toshiki Nanya
  • Patent number: 5314777
    Abstract: A negatively chargeable toner for developing latent electrostatic images is composed of a coloring agent; releasing agent; a binder resin including a polyester and a styrene - acryl-based polymer component with a weight-average molecular weight of 50,000 to 150,000, a number-average molecular weight of 2,000 to 12,000, and a glass transition temperature of 55.degree. to 70.degree. C. at a mixing ratio by weight in the range of (95:5) to (50:50); and a charge controlling agent including at least one phthalic ester which is mixed with the styrene - acryl-based polymer component, and at least one fluorine-containing quaternary ammonium salt.
    Type: Grant
    Filed: June 14, 1993
    Date of Patent: May 24, 1994
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuhito Watanabe, Toshiki Nanya, Yasuaki Iwamoto
  • Patent number: 5225303
    Abstract: A dry-type toner for electrophotography composed of a binder resin, a coloring agent, and a release agent which contains as the main components a carnauba wax substantially free of free aliphatic acids and/or a montan ester wax, and an oxidized rice wax with an acid value of 10 to 30.
    Type: Grant
    Filed: October 3, 1991
    Date of Patent: July 6, 1993
    Assignee: Ricoh Company, Ltd.
    Inventors: Masami Tomita, Toshiki Nanya, Yasuaki Iwamoto
  • Patent number: 4980258
    Abstract: The present invention relates to the positively chargeable black toner particles which comprise binder resins, carbonblack as a main colorant, quaternary anmonium salt of the following formula (I) as a charge control agent and .beta.-form Cu-phthalocyanine as a stabilizing agent for chargeability of toner particles without being affected by the change of environmental conditions. ##STR1## Wherein R.sub.1 is C.sub.1 -C.sub.8 alkyl or benzyl, R.sub.2 and R.sub.3 are each C.sub.1 -C.sub.18 alkyl, R is C.sub.1 -C.sub.118 alkyl or benzyl, X is hydroxy or amino, and Y is hydoroxy or hydrogen; (c) .beta.-form Cu-phthalocyanine; and (d) carbonblack.The present invention further relates to the two component dry-type developer composed by the improved above said positively chargeable toner particles and the carrier particles coated with silicone polylmers which have the strong durability without being changed to a supent carrier particles for a use of long time period.
    Type: Grant
    Filed: November 14, 1989
    Date of Patent: December 25, 1990
    Assignee: Ricoh Company, Ltd.
    Inventors: Mitsuo Aoki, Nobuhiro Nakayama, Yasuo Asahina, Hiroyuki Fushimi, Kayo Makita, Yasuaki Iwamoto
  • Patent number: 4945022
    Abstract: A triboelectric charge application member for imparting or applying electrostatic charge to a toner through the triboelectric charging thereof for developing electrostatic images with the charge toner to visible toner images. The triboelectric charge application member includes an overcoat layer comprising as the main component a polymer which comprises a fluoro-olefin compound and an unsaturated silicon compound as the monomer units of the polymer. The triboelectric charge application member may be carrier particles having the above overcoat layer and a toner transportation member having the overcoat layer, depending upon its application.
    Type: Grant
    Filed: March 14, 1989
    Date of Patent: July 31, 1990
    Assignee: Ricoh Company, Ltd.
    Inventors: Nobuhiro Nakayama, Yasuo Asahina, Hiroyuki Fushimi, Yasuaki Iwamoto
  • Patent number: 4841331
    Abstract: A triboelectric charge application member for imparting or applying electrostatic charge to a toner through the triboelectric charging thereof for developing electrostatic images with the charged toner to visible toner images. The triboelectric charge application member includes an overcoat layer comprising as the main component a polymer which comprises a fluoro-olefin compound and an unsaturated silicon compound as the monomer units of the polymer. The triboelectric charge application member may be carrier particles having the above overcoat layer and a toner transportation member having the overcoat layer, depending upon its application.
    Type: Grant
    Filed: March 3, 1988
    Date of Patent: June 20, 1989
    Assignee: Ricoh Company, Ltd.
    Inventors: Nobuhiro Nakayama, Yasuo Asahina, Hiroyuki Fushimi, Yasuaki Iwamoto