Patents by Inventor Naoki Imahashi

Naoki Imahashi 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: 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: 8067141
    Abstract: A carrier is provided including a core and a resin layer located overlying the core, wherein the carrier has a weight average particle diameter (Dw) of from 22 to 50 ?m, a ratio (Dw/Dp) of the weight average particle diameter (Dw) to a number average particle diameter (Dp) of from 1 to 1.30, a shape factor SF-1 of from 100 to 120, and a shape factor SF-2 of from 100 to 120, and wherein the carrier comprises core particles satisfying the following relationship 0.52<(d/D)<1.0 in an amount of from 0 to 10,000 ppm by number: wherein D (?m) represents a diameter of a circle having the same area as that of a projected image of a core particle and d (?m) represents a diameter of a circle having the same area as that of a projected image of a maximum hollow present in the core particle.
    Type: Grant
    Filed: August 31, 2007
    Date of Patent: November 29, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Naoki Imahashi, Masashi Nagayama
  • Patent number: 8039189
    Abstract: The present invention can provide small-diameter core material particles for electro photographic carrier, the particles that can prevent occurrences of carrier adhesions and reduce toner spent, have excellent durability and cause little fluctuations in image density with a narrow particle diameter distribution, and an efficient, cost-effective production method thereof. That is, the core material particles for electro photographic carrier are particles wherein the weight average particle diameter, Dw, is in the range of 22 ?m to 32 ?m, the ratio of Dw to the number average particle diameter, Dp, satisfies the condition, 1<Dw/Dp<1.20, the content of particles smaller than 20 ?m in diameter is in the range of 0% by mass to 7% by mass and smaller than 36 ?m is in the range of 90% by mass to 100% by mass, and the BET specific surface area is in the range of 300 cm2/g to 900 cm2/g.
    Type: Grant
    Filed: April 17, 2007
    Date of Patent: October 18, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Naoki Imahashi, Masashi Nagayama
  • Patent number: 7763410
    Abstract: A vibrating sieve for classifying a particulate material, including an oscillator comprising a transducer; and at least two meshes layered together and located in contacting relation to a transducer, wherein a lowermost mesh receiving a vibration from the transducer transmits the vibration to an uppermost mesh to classify the particulate material fed thereon.
    Type: Grant
    Filed: November 1, 2004
    Date of Patent: July 27, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Masashi Nagayama, Naoki Imahashi
  • Publication number: 20090092920
    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: Application
    Filed: March 6, 2007
    Publication date: April 9, 2009
    Inventors: Masashi Nagayama, Kimitoshi Yamaguchi, Naoki Imahashi
  • Publication number: 20090041510
    Abstract: An image forming apparatus is provided containing an image bearing member, a developer bearing member, and a developer control member being magnetic. The electrostatic latent image on the image bearing member is developed with a toner to form a toner image. The carrier includes magnetic core particles having a cover layer on the surfaces thereof, including fine particles having a weight average particle diameter of from 0.02 to 0.5 ?m. The carrier has a weight average particle diameter of from 22 to 32 ?m, and a ratio (E10/E100) of from 1.00 to 1.20. The ratio (E10/E100) is a ratio of a total energy (E10) to a total energy (E100) at a leading edge speed of the blade of 10 mm/s and 100 mm/s, respectively, measured using a power rheometer at an angle of approach of ?5°.
    Type: Application
    Filed: August 11, 2008
    Publication date: February 12, 2009
    Inventors: Naoki Imahashi, Tomio Kondou, Kimitoshi Yamaguchi, Hitoshi Iwatsuki
  • Patent number: 7468233
    Abstract: Electro-photographic images having high picture quality and low carrier adhesion can be obtained using a two-component developer containing a carrier containing (A) a carrier containing a core containing a magnetic material, the core being coated with at least one resin layer; and (B) a toner; wherein the carrier has a weight average particle diameter Dw of 22-32 ?m; wherein a content of carrier particles having a diameter smaller than 20 ?m is 0-7% by weight based on the weight of the carrier; wherein a content of carrier particles having a diameter smaller than 36 ?m is 90-100% by weight based on the weight of the carrier; wherein a weight average particle diameter Dw of the toner is 2-7 ?m; and wherein a ratio Dw/Dn of the weight average particle diameter of the toner to the number average particle diameter of the toner is 1.00-1.25.
    Type: Grant
    Filed: September 12, 2005
    Date of Patent: December 23, 2008
    Assignee: Ricoh Company, Ltd.
    Inventors: Masashi Nagayama, Kimitoshi Yamaguchi, Naoki Imahashi
  • Publication number: 20080227004
    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 (LogR) of 11 ?·cm to 17 ?·cm and a relaxation time ? of 150 seconds to 800 seconds.
    Type: Application
    Filed: March 14, 2008
    Publication date: September 18, 2008
    Inventors: Kimitoshi YAMAGUCHI, Naoki Imahashi, Kousuke Suzuki
  • Publication number: 20080073252
    Abstract: A vibrating sieve for classifying a particulate material, including an oscillator comprising a transducer; and at least two meshes layered together and located in contacting relation to a transducer, wherein a lowermost mesh receiving a vibration from the transducer transmits the vibration to an uppermost mesh to classify the particulate material fed thereon.
    Type: Application
    Filed: November 20, 2007
    Publication date: March 27, 2008
    Inventors: Kimitoshi YAMAGUCHI, Masashi NAGAYAMA, Naoki IMAHASHI
  • Publication number: 20080063969
    Abstract: A carrier is provided including a core and a resin layer located overlying the core, wherein the carrier has a weight average particle diameter (Dw) of from 22 to 50 ?m, a ratio (Dw/Dp) of the weight average particle diameter (Dw) to a number average particle diameter (Dp) of from 1 to 1.30, a shape factor SF-1 of from 100 to 120, and a shape factor SF-2 of from 100 to 120, and wherein the carrier comprises core particles satisfying the following relationship 0.52<(d/D)<1.0 in an amount of from 0 to 10,000 ppm by number: wherein D (?m) represents a diameter of a circle having the same area as that of a projected image of a core particle and d (?m) represents a diameter of a circle having the same area as that of a projected image of a maximum hollow present in the core particle.
    Type: Application
    Filed: August 31, 2007
    Publication date: March 13, 2008
    Inventors: Kimitoshi Yamaguchi, Naoki Imahashi, Masashi Nagayama
  • Patent number: 7320852
    Abstract: A carrier for use with a toner as a two-component type developer for developing an electrostatic image, comprising spherical magnetic core particles, and a resin layer covering each of said core particles and containing at least two resistance controlling materials having different specific resistances, wherein each of the resistance controlling materials is in the form of particles having a number average particle diameter of no more than 1/10 of a number average particle diameter of the toner.
    Type: Grant
    Filed: March 21, 2003
    Date of Patent: January 22, 2008
    Assignee: Ricoh Company, Ltd.
    Inventors: Akihiro Kotsugai, Kimitoshi Yamaguchi, Naoki Imahashi, Hiroaki Takahashi
  • Publication number: 20070243482
    Abstract: The present invention can provide small-diameter core material particles for electrophotographic carrier, the particles that can prevent occurrences of carrier adhesions and reduce toner spent, have excellent durability and cause little fluctuations in image density with a narrow particle diameter distribution, and an efficient, cost-effective production method thereof. That is, the core material particles for electrophotographic carrier are particles wherein the weight average particle diameter, Dw, is in the range of 22 ?m to 32 ?m, the ratio of Dw to the number average particle diameter, Dp, satisfies the condition, 1<Dw/Dp<1.20, the content of particles smaller than 20 ?m in diameter is in the range of 0% by mass to 7% by mass and smaller than 36 ?m is in the range of 90% by mass to 100% by mass, and the BET specific surface area is in the range of 300 cm2/g to 900 cm2/g.
    Type: Application
    Filed: April 17, 2007
    Publication date: October 18, 2007
    Inventors: Kimitoshi YAMAGUCHI, Naoki Imahashi, Masashi Nagayama
  • Patent number: 7192679
    Abstract: The present invention relates to a carrier for electrophotographic developers, a developer containing the carrier, a container for the developer, a image forming apparatus using the developer, an image forming method using the same, and a method of making the carrier.
    Type: Grant
    Filed: March 18, 2004
    Date of Patent: March 20, 2007
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Naoki Imahashi, Akihiro Kotsugai, Hiroaki Takahashi
  • Publication number: 20070048652
    Abstract: The present invention provides a carrier which contains core material particles having magnetism and a coating layer on the surfaces of the core material particles; in which the particle density of the core material particles is 4.0 g/cm3 to 6.0 g/cm3, and the bulk density of the core material particles is 2.0 g/cm3 to 3.0 g/cm3; and also provides a developer using the carrier, an image forming method using the developer, an image forming apparatus using the developer, and a process cartridge using the developer.
    Type: Application
    Filed: August 24, 2006
    Publication date: March 1, 2007
    Inventors: Naoki Imahashi, Kimitoshi Yamaguchi, Masashi Nagayama
  • Publication number: 20060210905
    Abstract: A carrier including a magnetic core material; and a resin layer located on the core material, wherein the carrier has a weight average particle diameter (Dw) of from 22 ?m to 32 ?m, a ratio Dw/Dp of greater than 1.0 and less than 1.2, wherein Dp represents a number average particle diameter of the carrier, and includes carrier particles having a particle diameter of less than 20 ?m in an amount of 0 to 7% by weight, and carrier particles having a particle diameter of less than 36 ?m in the carrier in an amount of 90 to 100% by weight, and the core material has a volume resistivity log (R1) of from 8.0 to 10.5 in an electric field of 50 V/mm and a ratio log (R2)/log (R3) of from 0.85 to 1.0, wherein R2 and R3 represent volume resistivities of chains of particles of the core material in electric fields of 250 V/mm and 50 V/mm, respectively.
    Type: Application
    Filed: March 13, 2006
    Publication date: September 21, 2006
    Inventors: Naoki Imahashi, Kimitoshi Yamaguchi, Masashi Nagayama
  • Publication number: 20060057487
    Abstract: Electro-photographic images having high picture quality and low carrier adhesion can be obtained using a two-component developer containing a carrier containing (A) a carrier containing a core containing a magnetic material, the core being coated with at least one resin layer; and (B) a toner; wherein the carrier has a weight average particle diameter Dw of 22-32 ?m; wherein a content of carrier particles having a diameter smaller than 20 ?m is 0-7% by weight based on the weight of the carrier; wherein a content of carrier particles having a diameter smaller than 36 ?m is 90-100% by weight based on the weight of the carrier; wherein a weight average particle diameter Dw of the toner is 2-7 ?m; and wherein a ratio Dw/Dn of the weight average particle diameter of the toner to the number average particle diameter of the toner is 1.00-1.25.
    Type: Application
    Filed: September 12, 2005
    Publication date: March 16, 2006
    Applicant: RICOH COMPANY, LIMITED.
    Inventors: Masashi Nagayama, Kimitoshi Yamaguchi, Naoki Imahashi
  • Patent number: 6939654
    Abstract: A carrier develops latent electrostatic images in corporation with a toner and one particle of the carrier includes a magnetic particle, and a coating layer covering the magnetic particle. The coating layer includes a crosslinked condensation product of a composition containing (i) an N-alkoxyalkylated polyamide and (ii) at least one resin that is reactive with the alkoxyalkylated polyamide and includes a silicone having a silanol group and/or a hydrolyzable group.
    Type: Grant
    Filed: December 4, 2003
    Date of Patent: September 6, 2005
    Assignee: Ricoh Company, Ltd.
    Inventors: Akihiro Kotsugai, Kimitoshi Yamaguchi, Motoharu Tanaka, Naoki Imahashi, Hiroaki Takahashi
  • Publication number: 20050158643
    Abstract: A vibrating sieve for classifying a particulate material, including an oscillator comprising a transducer; and at least two meshes layered together and located in contacting relation to a transducer, wherein a lowermost mesh receiving a vibration from the transducer transmits the vibration to an uppermost mesh to classify the particulate material fed thereon.
    Type: Application
    Filed: November 1, 2004
    Publication date: July 21, 2005
    Inventors: Kimitoshi Yamaguchi, Masashi Nagayama, Naoki Imahashi
  • Publication number: 20050064315
    Abstract: The present invention relates to a carrier for electrophotographic developers, a developer containing the carrier, a container for the developer, a image forming apparatus using the developer, an image forming method using the same, and a method of making the carrier.
    Type: Application
    Filed: March 18, 2004
    Publication date: March 24, 2005
    Inventors: Kimitoshi Yamaguchi, Naoki Imahashi, Akihiro Kotsugai, Hiroaki Takahashi