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: 9029061
    Abstract: A carrier for use in a two component developer for developing an electrostatic latent image is provided. The carrier includes a particulate core material; and a cover layer located on a surface of the core material and including a silicone resin and barium sulfate. The cover layer includes Ba and Si at an atomic ratio of from 0.01 to 0.08 as determined by X-ray photoelectron spectroscopy.
    Type: Grant
    Filed: December 27, 2010
    Date of Patent: May 12, 2015
    Assignee: Ricoh Company, Limited
    Inventors: Koichi Sakata, Minoru Masuda, Hisashi Nakajima, Kimitoshi Yamaguchi, Yutaka Takahashi, Hitoshi Iwatsuki, Saori Yamada, Toyoaki Tano
  • Patent number: 8877418
    Abstract: The developing method includes developing an electrostatic latent image on an image bearing member with a two-component developer including a toner and a carrier and born on at least one developer bearing member, whose surface moves at a linear speed of from 300 mm/sec to 2,000 mm/sec. The carrier includes a particulate core material; and a cover layer located on a surface of the core material and including a crosslinked material obtained by crosslinking a resin including a first unit having a specific tris(trialkylsiloxy) silyl group and a second unit having a specific alkoxysilyl group having a crosslinking ability. Each of the first unit and the second unit is included in the resin in a molar ratio of from 0.1 to 0.9 based on all the units included in the resin.
    Type: Grant
    Filed: July 19, 2011
    Date of Patent: November 4, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Hisashi Nakajima, Kimitoshi Yamaguchi, Shigenori Yaguchi, Hitoshi Iwatsuki, Toyoaki Tano, Mariko Takii, Minoru Masuda, Koichi Sakata, Saori Yamada, Hiroyuki Kishida
  • Patent number: 8778587
    Abstract: A carrier for developing an electrostatic latent image, including a particulate core material having a magnetism having developed spontaneous magnetization; and a covering layer comprising an electroconductive material, covering the surface of the particulate core material, wherein the carrier has an electrical resistivity Log R [?cm] of from 8.0 to 12.0 when measured by a method, including filling the carrier in a cell containing a pair of facing electrodes, each having a surface area of 2×4 [cm2] with a gap of 2 [mm] therebetween; and applying a DC voltage of 1,000 [V] therebetween to measure a DC resistivity, and a weight-average particle diameter (Dw) of from 25 to 45 ?m.
    Type: Grant
    Filed: October 10, 2012
    Date of Patent: July 15, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Shigenori Yaguchi, Toyoshi Sawada, Hiroshi Tohmatsu, Hitoshi Iwatsuki, Toyoaki Tano
  • Patent number: 8728698
    Abstract: The present invention is to provide a carrier and a developer, which have fewer occurrences of carrier adhesion and background smear, excellent granularity and longer durability. The carrier comprises the core material particles having magnetism and resin coating layer covering the core material particles, and wherein the weight average particle diameters is in the range of 22 m to 32 m, the proportion of the weight average particle diameters relative to the number average particle diameter is in the range of 1.00 to 1.20, the content of particles having a diameter of 20 m or smaller is 7% by mass, the content of carrier particles having a diameter of 36 m or smaller is in the range of 90% by mass to 100% by mass, and the proportion of the particle density of the core material particles is in the range of 85% to 100% of the true density of the core material particles.
    Type: Grant
    Filed: March 6, 2007
    Date of Patent: May 20, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Masashi Nagayama, Kimitoshi Yamaguchi, Naoki Imahashi
  • Patent number: 8679719
    Abstract: An object of the present invention is to provide a carrier containing core material particles having magnetism and a coating layer on the surfaces of the core material particles, wherein the core material particles have a magnetization at a magnetic field of 1,000 Oersted of 40 emu/g to 100 emu/g, and the carrier has a weight average particle diameter of 20 ?m to 45 ?m, a resistance (Log R) of 11 ?·cm to 17 ?·cm and a relaxation time ? of 150 seconds to 800 seconds.
    Type: Grant
    Filed: March 14, 2008
    Date of Patent: March 25, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Naoki Imahashi, Kousuke Suzuki
  • Patent number: 8663892
    Abstract: A latent electrostatic image developing carrier including: core particles each having magnetism; and a coating layer covering each of the core particles, wherein the latent electrostatic image developing carrier has a shape factor SF-2 of 115 to 150 and has a bulk density of 1.8 g/cm3 to 2.4 g/cm3, wherein the core particles have a shape factor SF-2 of 120 to 160 and have an arithmetic mean surface roughness Ra of 0.5 ?m to 1.0 ?m, and wherein the coating layer contains a resin and a filler and an amount of the filler contained in the coating layer is 50 parts by mass to 500 parts by mass per 100 parts by mass of the resin contained in the coating layer.
    Type: Grant
    Filed: August 23, 2012
    Date of Patent: March 4, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Shigenori Yaguchi, Kimitoshi Yamaguchi, Toyoshi Sawada, Hitoshi Iwatsuki, Toyoaki Tano, Hiroshi Tohmatsu
  • Patent number: 8652738
    Abstract: A contact developing method including supplying a two-component developer to an electrostatic latent image on a rotating image bearing member by rotating a developing sleeve and a rotatable magnet having multiple magnetic poles provided inside the developing sleeve, to develop the electrostatic latent image into a toner image. The developing sleeve and the image bearing member rotate in the same direction while facing each other. The two-component developer comprises a non-magnetic toner and a carrier. The carrier comprises a magnetic core particle and a resin layer covering the magnetic core particle. The resin layer comprises a conductive particle and a resin. The conductive particle comprises an alumina-based material and a conductive layer covering the alumina-based material. The resin is obtained by heating a copolymer comprising a monomer A unit and a monomer B unit.
    Type: Grant
    Filed: July 13, 2011
    Date of Patent: February 18, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Shigenori Yaguchi, Hitoshi Iwatsuki, Mariko Takii, Toyoshi Sawada, Toyoaki Tano, Hiroshi Tohmatsu, Koichi Sakata, Hiroyuki Kishida, Saori Yamada
  • Patent number: 8652735
    Abstract: A carrier including a magnetic core particle and a resin layer covering a surface of the magnetic core particle. The magnetic core particle is a ferrite particle including strontium in an amount of 0.005 to 3% by mass, measured by fluorescent X-ray spectroscopy. The resin layer comprises a resin obtained by heating a copolymer comprising a silicon-containing unit A and another silicon-containing specific unit B.
    Type: Grant
    Filed: August 19, 2011
    Date of Patent: February 18, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Koichi Sakata, Shigenori Yaguchi, Toyoshi Sawada, Kimitoshi Yamaguchi, Hitoshi Iwatsuki, Hiroshi Tohmatsu, Hiroyuki Kishida, Toyoaki Tano, Mariko Takii
  • Patent number: 8637218
    Abstract: A carrier for developing electrostatic latent image, including a core material; and a coated layer covering the core material, including a binder resin and a particulate material, wherein the core material is exposed on the surface of the carrier at an areal ratio of from 0.1 to 5.0% and has the largest exposed part having an areal ratio not greater than 0.03%, and wherein the coated layer comprises the particulate material in an amount of from 100 to 500 parts by weight per 100 parts by weight of the binder resin.
    Type: Grant
    Filed: July 24, 2012
    Date of Patent: January 28, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Koichi Sakata, Shigenori Yaguchi, Kimitoshi Yamaguchi, Toyoshi Sawada, Hiroshi Tohmatsu, Hiroyuki Kishida
  • Patent number: 8518626
    Abstract: The carrier is used for a two-component developer for developing an electrostatic latent image, and includes a particulate magnetic core material; and a cover layer located on a surface of the particulate magnetic core material and including a crosslinked material. The crosslinked material is formed by hydrolyzing a copolymer including at least a unit (A) having a specific acrylic siloxane structure including a tris(trialkylsiloxy)silanyl group and a unit (B) having a specific acrylic silicone structure to form a material having a silanol group, and subjecting the material having a silanol group to a condensation reaction using an organic zirconium-containing catalyst.
    Type: Grant
    Filed: March 1, 2011
    Date of Patent: August 27, 2013
    Assignee: Ricoh Company, Limited
    Inventors: Saori Yamada, Minoru Masuda, Hisashi Nakajima, Kimitoshi Yamaguchi, Koichi Sakata, Hitoshi Iwatsuki, Yutaka Takahashi, Toyoaki Tano, Mariko Takii
  • Patent number: 8512928
    Abstract: A carrier comprising a magnetic core particle having a shape factor SF-2 of 130 to 160 and a resin layer covering a surface of the magnetic core particle. The resin layer comprises a conductive particle and a resin obtained by heating a copolymer comprising a silicon-containing A unit and another silicon-containing B unit.
    Type: Grant
    Filed: September 6, 2011
    Date of Patent: August 20, 2013
    Assignee: Rocoh Company, Ltd.
    Inventors: Hiroyuki Kishida, Shigenori Yaguchi, Kimitoshi Yamaguchi, Toyoshi Sawada, Hiroshi Tohmatsu, Koichi Sakata, Hitoshi Iwatsuki, Toyoaki Tano, Mariko Takii
  • Patent number: 8512929
    Abstract: A latent electrostatic image developing carrier including a carrier core material, and a coating layer containing a resin and provided on a surface of the carrier core material, wherein the coating layer includes a particulate material containing at least first fine conductive particles and second fine conductive particles, and wherein the first fine conductive particles and the second fine conductive particles satisfy the relationships expressed by Expressions 1 and 2, 3?D1/D2?15 . . . Expression 1, where D1 denotes a dispersed particle diameter of the first fine conductive particles and D2 denotes a dispersed particle diameter of the second fine conductive particles, and ?7E?R1×R2?8E . . . Expression 2, where R1 denotes a powder specific resistance of the first fine conductive particles and R2 denotes a powder specific resistance of the second fine conductive particles.
    Type: Grant
    Filed: September 10, 2010
    Date of Patent: August 20, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Hitoshi Iwatsuki, Kimitoshi Yamaguchi, Minoru Masuda, Yutaka Takahashi, Koichi Sakata, Toyoaki Tano
  • Patent number: 8481239
    Abstract: A carrier, including a magnetic particulate core material and a resin layer on the core material, wherein the resin layer includes a resin obtained by heat treatment of a copolymer including a site derived from a monomer component having the following formula (1) and a site derived from a monomer component having the following formula (2), and includes a cross-linked material obtained by hydrolysis of the copolymer to produce a silanol group and condensation using an organotitanium compound: wherein R1 represents a hydrogen atom or a methyl group; m represents an alkylene group having 1 to 8 carbon atoms; R2 represents an alkyl group having 1 to 4 carbon atoms; R3 represents an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms; X represents 10 to 90 mol %; and Y represents 10 to 90 mol %.
    Type: Grant
    Filed: October 1, 2010
    Date of Patent: July 9, 2013
    Assignee: Ricoh Company Limited
    Inventors: Hisashi Nakajima, Kimitoshi Yamaguchi, Minoru Masuda, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki, Saori Yamada, Toyoaki Tano
  • Patent number: 8475989
    Abstract: The carrier is used for a two-component developer for developing an electrostatic latent image, and includes a particulate magnetic core material; and a cover layer located on a surface of the core material and including a crosslinked material and barium sulfate. The cover layer is formed by applying a coating medium including barium sulfate, a copolymer including a unit (A) having a specific acrylic siloxane structure including a tris(trialkylsiloxy)silanyl group and a unit (B) having a specific acrylic silicone structure having a crosslinking ability, and a condensation reaction catalyst, heating the applied medium to a temperature of from 100° C. to 230° C. so that the copolymer is hydrolyzed to produce a material having a silanol group, and the material and the catalyst are subjected to a condensation reaction to form the crosslinked material.
    Type: Grant
    Filed: October 4, 2010
    Date of Patent: July 2, 2013
    Assignee: Ricoh Company, Limited
    Inventors: Yutaka Takahashi, Minoru Masuda, Kimitoshi Yamaguchi, Hisashi Nakajima, Koichi Sakata, Hitoshi Iwatsuki, Saori Yamada, Toyoaki Tano, Mariko Takii
  • Patent number: 8431312
    Abstract: The present invention provides a carrier which includes core material particles, and a coating layer on surfaces of the core material particles, wherein the coating layer contains a crosslinked product which is obtained by condensation of a silicone resin with an organic zirconium catalyst, the silicone resin having at least one of a silanol group and a functional group capable of generating a silanol group by means of hydrolysis.
    Type: Grant
    Filed: November 10, 2009
    Date of Patent: April 30, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Minoru Masuda, Kimitoshi Yamaguchi, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki
  • Publication number: 20130101930
    Abstract: A carrier for developing an electrostatic latent image, including a particulate core material having a magnetism having developed spontaneous magnetization; and a covering layer comprising an electroconductive material, covering the surface of the particulate core material, wherein the carrier has an electrical resistivity Log R [?cm] of from 8.0 to 12.
    Type: Application
    Filed: October 10, 2012
    Publication date: April 25, 2013
    Inventors: Kimitoshi Yamaguchi, Shigenori Yaguchi, Toyoshi Sawada, Hiroshi Tohmatsu, Hitoshi Iwatsuki, Toyoaki Tano
  • Publication number: 20130065175
    Abstract: A carrier for developing electrostatic latent image, including a core material; and a coated layer covering the core material, including a binder resin and a particulate material, wherein the core material is exposed on the surface of the carrier at an areal ratio of from 0.1 to 5.0% and has the largest exposed part having an areal ratio not greater than 0.03%, and wherein the coated layer comprises the particulate material in an amount of from 100 to 500 parts by weight per 100 parts by weight of the binder resin.
    Type: Application
    Filed: July 24, 2012
    Publication date: March 14, 2013
    Inventors: Koichi Sakata, Shigenori Yaguchi, Kimitoshi Yamaguchi, Toyoshi Sawada, Hiroshi Tohmatsu, Hiroyuki Kishida
  • Publication number: 20130065171
    Abstract: A latent electrostatic image developing carrier including: core particles each having magnetism; and a coating layer covering each of the core particles, wherein the latent electrostatic image developing carrier has a shape factor SF-2 of 115 to 150 and has a bulk density of 1.8 g/cm3 to 2.4 g/cm3, wherein the core particles have a shape factor SF-2 of 120 to 160 and have an arithmetic mean surface roughness Ra of 0.5 ?m to 1.0 ?m, and wherein the coating layer contains a resin and a filler and an amount of the filler contained in the coating layer is 50 parts by mass to 500 parts by mass per 100 parts by mass of the resin contained in the coating layer.
    Type: Application
    Filed: August 23, 2012
    Publication date: March 14, 2013
    Inventors: Shigenori Yaguchi, Kimitoshi Yamaguchi, Toyoshi Sawada, Hitoshi Iwatsuki, Toyoaki Tano, Hiroshi Tohmatsu
  • Patent number: 8257896
    Abstract: A carrier which is capable of avoiding excess blocking of the carrier particles at the time of forming a covering layer and is excellent in durability, a developer containing the carrier, and a developer container containing the developer, as well as an image forming method and a process cartridge which use the developer are provided. A carrier including at least a core material particle and a covering layer, a surface of the core material particle being covered with the covering layer, wherein the covering layer contains a condensate which is obtained by condensation of a silicone resin having at least one of a silanol group and a functional group which can be converted to the silanol group by hydrolysis, using a titanium diisopropoxy bis(ethylaceto-acetate) catalyst.
    Type: Grant
    Filed: March 10, 2010
    Date of Patent: September 4, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Minoru Masuda, Kimitoshi Yamaguchi, Yutaka Takahashi, Koichi Sakata, Hitoshi Iwatsuki, Toyoaki Tano
  • Patent number: 8247150
    Abstract: A carrier for developing an electrostatic latent image which includes a core material and a resin coating layer provided on the core material. The resin coating layer includes a resin and a particulate tin oxide, and the surface of the particulate tin oxide is coated with carbon.
    Type: Grant
    Filed: September 17, 2009
    Date of Patent: August 21, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Hitoshi Iwatsuki, Kimitoshi Yamaguchi, Minoru Masuda, Yutaka Takahashi, Koichi Sakata