Patents by Inventor Yoshimichi Ishikawa

Yoshimichi Ishikawa 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: 20120237267
    Abstract: An electrostatic image developing toner including: toner particles each containing binder resin and colorant; and an external additive supported on the toner particles, wherein the toner particles each have protrusions on surface thereof, average of lengths of long sides of the protrusions is 0.10 ?m or more but less than 0.50 ?m, standard deviation of the lengths of the long sides of the protrusions is 0.20 or less, coverage rate of the protrusions on the surface of each toner particle is 30% to 90%, the external additive includes at least two different particles including external additive (A) and one or more external additives (B), external additive (A) has longest average primary particle diameter among the external additives and charged to have the opposite polarity to the toner particles, and at least one of the external additives (B) is charged to have the same polarity as the toner particles.
    Type: Application
    Filed: March 16, 2012
    Publication date: September 20, 2012
    Inventors: Tomohiro FUKAO, Takuya Kadota, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Yoshimichi Ishikawa, Kazuoki Fuwa, Tomoharu Miki
  • Patent number: 8268527
    Abstract: A toner is provided including a core particle comprising a binder resin, a colorant, and a release agent, and a shell layer comprising particles of a vinyl resin. The vinyl resin comprises 80% by weight or more of a unit of an aromatic compound having a vinyl-polymerizable functional group. A method of manufacturing the above toner is also provided, including steps of dissolving or dispersing the binder resin, the colorant, and the release agent in an organic solvent to prepare an oily liquid, dispersing the oily liquid in an aqueous medium to prepare the core particles, and adhering particles of a vinyl resin to the surfaces of the core particles to form shell layers.
    Type: Grant
    Filed: August 11, 2010
    Date of Patent: September 18, 2012
    Assignee: Ricoh Company, Limited
    Inventors: Takuya Kadota, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Atsushi Yamamoto, Yoshimichi Ishikawa, Tomohiro Fukao, Tomoharu Miki
  • Publication number: 20120219321
    Abstract: A toner including a binder resin, a colorant and protruding portions on a surface of the toner, wherein the average length of long sides of the protruding portions is 0.1 ?m or greater, but less than 0.5 ?m, wherein the standard deviation of the lengths of the long sides of the protruding portions is 0.2 or less, and wherein the protruding portions have a coverage of 30% to 90%.
    Type: Application
    Filed: October 27, 2010
    Publication date: August 30, 2012
    Inventors: Tomohiro Fukao, Takuya Kadota, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Yoshimichi Ishikawa, Atsushi Yamamoto, Tomoharu Miki, Kazuoki Fuwa
  • Patent number: 8216755
    Abstract: A toner manufactured by a method including the steps of dissolving or dispersing toner components comprising a binder resin, a colorant, and an encapsulated plasticizer to prepare an oily toner components liquid, and emulsifying or dispersing the oily toner components liquid in an aqueous medium to prepare the toner.
    Type: Grant
    Filed: June 1, 2009
    Date of Patent: July 10, 2012
    Assignee: Ricoh Company, Limited
    Inventors: Yoshimichi Ishikawa, Chiyoshi Nozaki, Tsuyoshi Nozaki, Takuya Kadota, Katsunori Kurose, Mitsuyo Matsumoto, Atsushi Yamamoto
  • Patent number: 8139984
    Abstract: An image forming apparatus, wherein a surface resistivity Rse[?] of a charger and a volume resistivity Rsw [?·cm] of the composition having a low softening point satisfy the following relationship: 0.8×10?1Rse<Rvw<1.5×10Rse is provided. The image forming apparatus contains a photoreceptor; a charger configured to charge the photoreceptor with a charger contacting thereto; an irradiator configured to irradiate the photoreceptor to form an electrostatic latent image thereon; an image developer configured to develop the electrostatic latent image with a toner to form a toner image on the photoreceptor; a transferer configured to transfer the toner image onto a recording material directly or through an intermediate transferer; and a fixer configured to fix the toner image on the recording material, wherein the toner comprises: a binder resin; a colorant; a composition having a low softening point; and an external additive.
    Type: Grant
    Filed: October 26, 2010
    Date of Patent: March 20, 2012
    Assignee: Ricoh Company, Limited
    Inventors: Hiroyuki Murakami, Masahide Inoue, Chiyoshi Nozaki, Tsuyoshi Nozaki, Atsushi Yamamoto, Takuya Kadota, Mitsuyo Matsumoto, Katsunori Kurose, Yoshimichi Ishikawa
  • Patent number: 8110330
    Abstract: To provide a toner that contains at least a binder resin, a colorant, a releasing agent and zeolite, the toner being manufactured through O/W type wet granulation and having an average circularity of 0.970 or greater, and a developer and image forming method using the toner.
    Type: Grant
    Filed: September 18, 2007
    Date of Patent: February 7, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshimichi Ishikawa, Chiyoshi Nozaki, Tsuyoshi Nozaki, Takuya Kadota, Katsunori Kurose, Mitsuyo Matsumoto, Atsushi Yamamoto, Masahide Inoue
  • Publication number: 20110287356
    Abstract: An electrostatic image developing toner including toner core particles each containing at least a first resin and a colorant, and fine resin particles formed of a second resin, wherein part of each of the fine resin particles is embedded in each of the toner core particles, and the remaining part of the fine resin particle is exposed on a surface of the toner core particle to form a protrusion, and wherein when a rate of the part of the fine resin particle to the fine resin particle is indicated by an embedment rate, an average of the embedment rates in the fine resin particles is 40% to 80%.
    Type: Application
    Filed: May 23, 2011
    Publication date: November 24, 2011
    Inventors: Tomohiro Fukao, Takuya Kadota, Chieko Yamazaki, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Yoshimichi Ishikawa, Atsushi Yamamoto, Kazuoki Fuwa, Tomoharu Miki
  • Patent number: 8053154
    Abstract: A toner for electrostatic charge development is provided where the toner comprises a colorant and a resin and contains an organic boron compound represented by a following chemical formula (A) as a charge controlling agent, further the toner is treated with an inorganic fine particle and at least one of the inorganic particles is a magnesium silicate compound represented by a following general formula [2] is provided. wherein X is an alkali metal, R1, R2, R3 or R4 each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom. MgxSiyO(x+2y)??[2] wherein x and y are integers.
    Type: Grant
    Filed: March 2, 2007
    Date of Patent: November 8, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Takuya Kadota, Masayuki Hagi, Yoshihiro Mikuriya, Katsunori Kurose, Hiroaki Kato, Atsushi Yamamoto, Yoshimichi Ishikawa, Masahide Inoue, Minoru Nakamura, Hideaki Yasunaga
  • Patent number: 8043779
    Abstract: To provide a pulverized toner excellent in the releasing ability and cleaning ability, and an image-forming apparatus for one-component developer, and a process cartridge using the pulverized toner. The pulverized toner contains a toner base particle containing at least a binder resin, a colorant, and a releasing agent, the mass ratio of the releasing agent to the binder resin is 3.0% to 6.0%, the adhesive force among the pulverized toners at 25° C. to 55° C. is 20 g to 80 g, and the pulverized toner is used for the image-forming apparatus for one-component developer containing the cleaning unit configured to dispose an elastic blade adjacent to the surface of the image bearing member so as to clean the surface.
    Type: Grant
    Filed: March 9, 2007
    Date of Patent: October 25, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Hideaki Yasunaga, Hiroaki Kato, Masayuki Hagi, Katsunori Kurose, Yoshihiro Mikuriya, Yoshimichi Ishikawa, Atsushi Yamamoto, Takuya Kadota
  • Publication number: 20110250533
    Abstract: To provide a toner for an electrostatic image developer, including: a core particle obtained by dispersing, in an aqueous medium, an oil phase prepared by dissolving or dispersing at least a binder resin, a colorant and a release agent in an organic solvent; and a shell layer formed of vinyl resin fine particles present on a surface of the core particle, wherein the shell layer has protruding portions formed of the vinyl resin fine particles, and wherein the vinyl resin fine particles contain 80% by mass or more of an aromatic compound which has a vinyl-polymerizable functional group, and a vinyl resin which forms the vinyl resin fine particles has a weight average molecular weight of 8,000 to 16,000.
    Type: Application
    Filed: April 11, 2011
    Publication date: October 13, 2011
    Inventors: Takuya Kadota, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Atsushi Yamamoto, Yoshimichi Ishikawa, Kazuoki Fuwa, Tomohiro Fukao, Tomoharu Miki
  • Patent number: 8012658
    Abstract: A toner including a binder resin including a polyester resin and a vinyl resin; a wax; and a colorant, wherein the vinyl resin includes a unit obtained from a radically polymerizable monomer having an alkyloxysilyl group. An image forming apparatus including an image bearing member configured to bear an electrostatic image thereon; a developing device configured to develop the electrostatic image with a developer including the toner to form a toner image on the image bearing member; and a transfer device configured to transfer the toner image onto a receiving material. A process cartridge including an image bearing member; and a developing device configured to develop an electrostatic image on the image bearing member with a developer including the toner, wherein the process cartridge is detachably attached to an image forming apparatus as a unit.
    Type: Grant
    Filed: February 5, 2008
    Date of Patent: September 6, 2011
    Assignee: Ricoh Company Limited
    Inventors: Chiyoshi Nozaki, Takuya Kadota, Katsunori Kurose, Mitsuyo Matsumoto, Tsuyoshi Nozaki, Yoshimichi Ishikawa, Atsushi Yamamoto, Hiroyuki Murakami
  • Publication number: 20110164901
    Abstract: A toner containing core particles each containing at least a resin A having a polyester skeleton and a colorant; and vinyl resin fine particles each of which encapsulates a resin B having at least a polyester skeleton and an endothermic peak measured by differential scanning calorimeter (DSC) at 40° C. to 110° C., wherein the vinyl resin fine particles are attached onto each of the core particles.
    Type: Application
    Filed: December 6, 2010
    Publication date: July 7, 2011
    Inventors: Atsushi YAMAMOTO, Takuya Kadota, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Yoshimichi Ishikawa, Kazuoki Fuwa, Tomohiro Fukao, Tomoharu Miki, Masayuki Hagi
  • Patent number: 7903998
    Abstract: An image forming apparatus having at least a latent electrostatic image bearing member, and a recharging unit configured to recharge a residual toner remaining on the latent electrostatic image bearing member, wherein after transfer, the residual toner is passed through the recharging unit and is then recovered in a developing device; a charging component of the recharging unit that comes into contact with the latent electrostatic image bearing member is a polymer sheet having a surface roughness (Ra) of 0.12 ?m to 0.51 ?m; the toner contains at least a pigment, a binder resin, and a releasing agent, and contains inorganic fine particles as an external additive, and the amount of the inorganic fine particles and the amount of the releasing agent satisfy three specific Expressions.
    Type: Grant
    Filed: March 12, 2008
    Date of Patent: March 8, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Mitsuyo Matsumoto, Chiyoshi Nozaki, Takuya Kadota, Katsunori Kurose, Tsuyoshi Nozaki, Atsushi Yamamoto, Yoshimichi Ishikawa
  • Publication number: 20110053063
    Abstract: A toner is provided including a core particle comprising a binder resin, a colorant, and a release agent, and a shell layer comprising particles of a vinyl resin. The vinyl resin comprises 80% by weight or more of a unit of an aromatic compound having a vinyl-polymerizable functional group. A method of manufacturing the above toner is also provided, including steps of dissolving or dispersing the binder resin, the colorant, and the release agent in an organic solvent to prepare an oily liquid, dispersing the oily liquid in an aqueous medium to prepare the core particles, and adhering particles of a vinyl resin to the surfaces of the core particles to form shell layers.
    Type: Application
    Filed: August 11, 2010
    Publication date: March 3, 2011
    Inventors: Takuya KADOTA, Yoshihiro MIKURIYA, Tsuyoshi NOZAKI, Atsushi YAMAMOTO, Yoshimichi ISHIKAWA, Tomohiro FUKAO, Tomoharu MIKI
  • Publication number: 20110053071
    Abstract: To provide a toner comprising: a binder resin, a colorant, and a releasing agent, wherein the toner has a core shell structure, and wherein the core contains at least one resin selected from the group consisting of a hybrid resin and a polyester resin, where the hybrid resin is a resin in which a polyester resin and a vinyl resin are chemically bonded to each other, and the shell contains a resin prepared by polymerizing at least a styrene monomer and an ester monomer represented by the following General Formula (1): where, ‘n’ is 2 or 3, ‘X’ is any of 0 to 9, R1 is a hydrogen atom, or an alkyl group, and R2 is a hydrogen atom, an alkyl group, or a phenyl group.
    Type: Application
    Filed: August 27, 2010
    Publication date: March 3, 2011
    Inventors: Tomoharu Miki, Takuya Kadota, Yoshihiro Mikuriya, Tsuyoshi Nozaki, Atsushi Yamamoto, Yoshimichi Ishikawa, Tomohiro Fukao
  • Publication number: 20110053077
    Abstract: The present invention provides a method for producing a colored resin particle, the method including: preparing an oil phase in which at least a resin and a colorant are dissolved or dispersed in an organic solvent; preparing an aqueous phase containing at least a surfactant in an aqueous medium; dispersing the oil phase in the aqueous phase to prepare a colored particle dispersion liquid so as to form core particles; causing resin fine particles to adhere to surfaces of the core particles by adding at least the resin fine particles to the colored particle dispersion liquid, in which the core particles have been formed; removing the solvent from the colored particle dispersion liquid to obtain colored resin particles, washing the colored resin particles, and drying the colored resin particles, wherein an inorganic base is dissolved in the colored particle dispersion liquid.
    Type: Application
    Filed: August 27, 2010
    Publication date: March 3, 2011
    Inventors: Yoshihiro MIKURIYA, Tomoharu Miki, Tomohiro Fukao, Kazuoki Fuwa, Takuya Kadota, Yoshimichi Ishikawa, Atsushi Yamamoto, Tsuyoshi Nozaki
  • Publication number: 20110045401
    Abstract: An image forming apparatus, wherein a surface resistivity Rse[?] of a charger and a volume resistivity Rsw [?·cm] of the composition having a low softening point satisfy the following relationship: 0.8×10?1Rse<Rvw<1.5×10Rse is provided. The image forming apparatus contains a photoreceptor; a charger configured to charge the photoreceptor with a charger contacting thereto; an irradiator configured to irradiate the photoreceptor to form an electrostatic latent image thereon; an image developer configured to develop the electrostatic latent image with a toner to form a toner image on the photoreceptor; a transferer configured to transfer the toner image onto a recording material directly or through an intermediate transferer; and a fixer configured to fix the toner image on the recording material, wherein the toner comprises: a binder resin; a colorant; a composition having a low softening point; and an external additive.
    Type: Application
    Filed: October 26, 2010
    Publication date: February 24, 2011
    Inventors: Hiroyuki MURAKAMI, Masahide Inoue, Chiyoshi Nozaki, Tsuyoshi Nozaki, Atsushi Yamamoto, Takuya Kadota, Mitsuyo Matsumoto, Katsunori Kurose, Yoshimichi Ishikawa
  • Patent number: 7867685
    Abstract: An image forming method, including charging a photoreceptor with a charger contacting thereto; irradiating the photoreceptor to form an electrostatic latent image thereon; developing the electrostatic latent image with a toner to form a toner image on the photoreceptor; transferring the toner image onto a recording material directly or through an intermediate transferer; and fixing the toner image on the recording material, wherein the toner includes a binder resin; a colorant; a composition having a low softening point; and an external additive, and wherein a surface resistivity Rse [?] of the charger and a volume resistivity Rsw [?·cm] of the composition having a low softening point satisfy the following relationship: 0.8×10?1Rse<Rvw<1.5×10Rse.
    Type: Grant
    Filed: September 7, 2007
    Date of Patent: January 11, 2011
    Assignee: Ricoh Company, Limited
    Inventors: Hiroyuki Murakami, Masahide Inoue, Chiyoshi Nozaki, Tsuyoshi Nozaki, Atsushi Yamamoto, Takuya Kadota, Mitsuyo Matsumoto, Katsunori Kurose, Yoshimichi Ishikawa
  • Patent number: 7838193
    Abstract: A toner including toner particles including a binder resin, a colorant and a release agent, and an external additive including a first particulate inorganic material having a formula of MgxSiyOx+2y where each of x and y is an integer, and a number average secondary particle diameter of from 0.02 ?m to 2 ?m, wherein the first atomic ratio (Mg/Si)s in a surface portion of the first particulate inorganic material is not greater than (preferably less than) the second atomic ratio (Mg/Si)e in the entire first particulate inorganic material. Alternatively, a toner including toner particles including a binder resin and a colorant, and an external additive which includes a particulate inorganic material having a formula of MgxSiyOx+2y where each of x and y is an integer and which has a surface treated with a fatty acid.
    Type: Grant
    Filed: February 1, 2007
    Date of Patent: November 23, 2010
    Assignee: Ricoh Company Limited
    Inventors: Masayuki Hagi, Takuya Kadota, Hiroaki Katoh, Atsushi Yamamoto, Katsunori Kurose, Yoshihiro Mikuriya, Masahide Inoue, Hideaki Yasunaga, Minoru Nakamura, Yoshimichi Ishikawa, Hiroyuki Murakami
  • Patent number: 7833686
    Abstract: A toner kit containing at least a black toner, a yellow toner, a magenta toner and a cyan toner, wherein these toners have at least the binder resin, the colorant and the charge controlling agent having the molecular structure containing K+ as the counterion, when the K+ intensity detected by the fluorescent X ray on the surface of the black toner is Kk, the K+ intensity detected by the fluorescent X ray on the surface of the yellow toner is Ky, the K+ intensity detected by the fluorescent X ray on the surface of the magenta toner is Km and the K+ intensity detected by the fluorescent X ray on the surface of the cyan toner is Kc, the following formulae: Kk<Ky, Kk<Km and Kk<Kc are fulfilled is provided.
    Type: Grant
    Filed: December 26, 2006
    Date of Patent: November 16, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Takuya Kadota, Minoru Nakamura, Masayuki Hagi, Yoshihiro Mikuriya, Katsunori Kurose, Hideaki Yasunaga, Hiroaki Kato, Yoshimichi Ishikawa, Atsushi Yamamoto, Masahide Inoue