Patents by Inventor Yoshiki Yanagawa

Yoshiki Yanagawa 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: 20110159418
    Abstract: A hydroxygallium phthalocyanine composite pigment, which is a composite pigment wherein an azo compound expressed by the following general formula (a) is conjugated to a hydroxygallium phthalocyanine pigment, wherein the hydroxygallium phthalocyanine composite pigment has diffraction peaks at least at 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° on an X-ray diffraction spectrum with Bragg angle of 2?±0.2°, using Cu—K? X-rays: A(H)n ??General Formula (a) where A is a residue of an azo compound; H is a hydrogen atom; the residue A is bonded to one or more hydrogen atoms, where the number of the hydrogen atoms is expressed with n, via one or more heteroatoms which are selected from the group consisting of N and O, and form part of the residue A; and n is an integer of 1 to 9.
    Type: Application
    Filed: December 10, 2010
    Publication date: June 30, 2011
    Inventors: Hiromi SAKAGUCHI, Masafumi Ohta, Yoshiki Yanagawa
  • Publication number: 20110159420
    Abstract: To provide a gallium phthalocyanine compound, which is expressed by the following general formula (I) where R1 to R32 are each independently a hydrogen atom, an alkoxy group, an alkylthio group, an alkyl group, a halogen atom, a nitro group, or an aryl group.
    Type: Application
    Filed: December 27, 2010
    Publication date: June 30, 2011
    Inventors: Hiromi Sakaguchi, Masafumi Ohta, Yoshiki Yanagawa
  • Publication number: 20110111335
    Abstract: To provide an electrophotographic photoconductor that has a layer containing a compound represented by the following general formula (1), and an image forming apparatus using the electrophotographic photoconductor.
    Type: Application
    Filed: November 5, 2010
    Publication date: May 12, 2011
    Inventors: Keisuke SHIMOYAMA, Eiji Kurimoto, Takeshi Orito, Tatsuya Niimi, Shinichi Kawamura, Yoshiki Yanagawa, Michitaka Sasaki
  • Patent number: 7937025
    Abstract: A scorotron corona charger including a grid electrode is provided. A layer including a zeolite, a resistance controlling agent, and a binder is formed on the grid electrode. The binder resin has a solubility parameter of 10.0 cal1/2cm?3/2 or less.
    Type: Grant
    Filed: September 2, 2009
    Date of Patent: May 3, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Shinji Nohsho, Yoshiki Yanagawa
  • Patent number: 7879519
    Abstract: This invention relates to image bearing member and an image forming apparatus that employs the image bearing member. The image bearing member contains an electroconductive substrate; a charge generation layer; a charge transport layer; a cross-linking surface protective layer, and a monomer having one radical polymerizable functional group with a charge transport structure. The cross-linking surface protective layer is formed by curing a monomer having at least three radical polymerizable functional groups without a charge transport structure. For the image bearing member, the ratio of the layer thickness of the cross linking surface protective layer to the layer thickness of the charge transport layer is from 0.7 to 1.3.
    Type: Grant
    Filed: February 14, 2008
    Date of Patent: February 1, 2011
    Assignee: Ricoh Company Limited
    Inventors: Naohiro Toda, Yoshiki Yanagawa, Takaaki Ikegami, Makoto Yasuda, Takeshi Orito
  • Patent number: 7871747
    Abstract: To provide an electrophotographic photoconductor that has a layer containing a compound represented by the following general formula (1), and an image forming apparatus using the electrophotographic photoconductor. where R1 and R2 independently represent any one of a hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group and substituted or unsubstituted aralkyl group, and R3, R4, R5, R6, R7, R8, R9 and R10 independently represent any one of a hydrogen atom, halogen atom, cyano group, nitro group, amino group, hydroxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group and substituted or unsubstituted aralkyl group.
    Type: Grant
    Filed: September 12, 2006
    Date of Patent: January 18, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Keisuke Shimoyama, Eiji Kurimoto, Takeshi Orito, Tatsuya Niimi, Shinichi Kawamura, Yoshiki Yanagawa, Michitaka Sasaki
  • Patent number: 7855040
    Abstract: A method for preparing a photoreceptor including forming a photosensitive layer overlying an electroconductive substrate; coating a liquid including a radically polymerizable compound to form a protective layer; irradiating the protective layer with light to crosslink the protective layer; and then contacting the protective layer with a fluid, which is selected from the group consisting of supercritical fluids and subcritical fluids and which includes a charge transport material. A photoreceptor prepared by the method. An image forming method, an image forming apparatus and a process cartridge using the photoreceptor.
    Type: Grant
    Filed: October 29, 2007
    Date of Patent: December 21, 2010
    Assignee: Ricoh Company Limited
    Inventors: Yoshiki Yanagawa, Michio Kimura, Nozomu Tamoto, Hiromi Tada, Tetsuya Toshine, Tomoyuki Shimada, Chiaki Tanaka
  • Patent number: 7851119
    Abstract: The present invention provides an electrophotographic photoconductor capable of reducing latent electrostatic image stability defects caused by adhesion/adsorption of an electric discharge product formed by a charger in an image forming process, degradation of charge transportability and cleaning defects caused when removing a residual toner.
    Type: Grant
    Filed: September 5, 2007
    Date of Patent: December 14, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Tetsuya Toshine, Chiaki Tanaka, Michio Kimura, Tomoyuki Shimada, Nozomu Tamoto, Yoshiki Yanagawa, Hiromi Tada
  • Publication number: 20100310975
    Abstract: An electrophotographic photoreceptor, including an electroconductive substrate; and a photosensitive layer overlying the substrate, wherein the photosensitive layer comprises a complex azo pigment comprising an azo compound having the following formula (a): A(H)n??(a) wherein A represents a residue of an azo compound, bonded with n pieces of hydrogen atom through one or more heteroatom being N or O and forming a part of the residue A; H represents a hydrogen atom; and n represents an integer of from 1 to 9, and a pigment.
    Type: Application
    Filed: June 2, 2010
    Publication date: December 9, 2010
    Applicant: RICOH COMPANY, LTD.
    Inventors: Hiromi Tada, Masafumi Ohta, Tatsuya Niimi, Norio Nagayama, Yoshiki Yanagawa, Yuuji Tanaka
  • Publication number: 20100209842
    Abstract: An electrophotographic photoreceptor, including at lest an electroconductive substrate and a photosensitive layer including at least a tri- or more functional radical polymerizing monomer having no charge transport structure and a monofunctional radical polymerizing compound having a charge transport structure, wherein the photosensitive layer includes radical polymerizing functional groups in an amount of from 2.55×1021 to 7.50×1021 in 1 g of solid contents thereof, and has a peel strength not less than 0.1 N/mm when measured by the SAICAS method.
    Type: Application
    Filed: February 16, 2010
    Publication date: August 19, 2010
    Inventors: Yoshiki YANAGAWA, Yoshiaki Kawasaki, Tetsuro Suzuki
  • Publication number: 20100067953
    Abstract: A scorotron corona charger including a grid electrode is provided. A layer including a zeolite, a resistance controlling agent, and a binder is formed on the grid electrode. The binder resin has a solubility parameter of 10.0 cal1/2cm?3/2 or less.
    Type: Application
    Filed: September 2, 2009
    Publication date: March 18, 2010
    Applicant: RICOH COMPANY, LTD.
    Inventors: Shinji NOHSHO, Yoshiki YANAGAWA
  • Publication number: 20100010204
    Abstract: A method of preparing a complex-azo pigment having plural pigment components including at least an azo pigment represented by the following formula (a) A(H)n ??(a) Pigments, both limited and unlimited by the process of making.
    Type: Application
    Filed: July 7, 2009
    Publication date: January 14, 2010
    Inventors: Masafumi OHTA, Hiromi Tada, Yoshiki Yanagawa
  • Patent number: 7629103
    Abstract: A photoconductor comprising a photosensitive layer disposed on an support, wherein the photosensitive layer has at least a crosslinked layer and the crosslinked layer is produced by curing at least a radical polymerizable monomer having three or more functionalities and no charge transport structure and a radical polymerizable compound having a charge transport structure through irradiating a light energy in an atmosphere having a low oxygen concentration of 0.001 vol % to 2.0 vol %.
    Type: Grant
    Filed: June 21, 2005
    Date of Patent: December 8, 2009
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Ikuno, Hiroshi Tamura, Tetsuro Suzuki, Yoshiki Yanagawa
  • Patent number: 7556903
    Abstract: An electrophotographic photoreceptor including an electroconductive substrate and a photosensitive layer overlying the electroconductive substrate. An outermost layer of the electrophotographic photoreceptor is a crosslinked layer including a radical polymerizing monomer having three or more functional groups without a charge transporting structure. The outermost layer also includes a radical polymerizing compound having one functional group with a charge transporting structure and a reactive silicone compound having a radical polymerizing functional group.
    Type: Grant
    Filed: September 20, 2004
    Date of Patent: July 7, 2009
    Assignee: Ricoh Company Limited
    Inventors: Yoshiki Yanagawa, Hiroshi Ikuno, Hongguo Li, Kazukiyo Nagai, Hiroshi Tamura, Tetsuro Suzuki
  • Publication number: 20090148186
    Abstract: A corona charger including a corona discharge electrode and a control electrode is provided. A layer including a zeolite, a conductive agent, and a binder resin is formed on a surface of the control electrode.
    Type: Application
    Filed: December 10, 2008
    Publication date: June 11, 2009
    Applicant: RICOH COMPANY, LTD
    Inventors: Makoto Yasuda, Naohiro Toda, Yoshiki Yanagawa, Takeshi Orito, Shinji Nohsho
  • Publication number: 20090035672
    Abstract: To provide an electrophotographic photoconductor that comprises a support and a cross-linked layer formed over the support, wherein the cross-linked layer comprises at least light curable of radically polymerizable compound, the difference of maximum value of the post-exposure electrical potential and minimum value of the post-exposure electrical potential when writing is conducted under the condition that image static power is 0.53 mW, exposure energy is 4.0 erg/cm2 for the electrophotographic photoconductor is within 30V.
    Type: Application
    Filed: February 27, 2007
    Publication date: February 5, 2009
    Inventors: Yoshiki Yanagawa, Yoshiaki Kawasaki, Tetsuro Suzuki
  • Patent number: 7473504
    Abstract: An electrophotographic photoreceptor including an electroconductive substrate; and a photosensitive layer located overlying the electroconductive substrate, wherein an outermost layer of the electrophotographic photoreceptor is a crosslinked layer, including: a urethane oligomer having a radical polymerizing functional group; and a radical polymerizing compound having one functional group with a charge transporting structure, or a radical polymerizing oligomer having a polyester structure; a radical polymerizing compound having three or more functional groups without a charge transporting structure; and a radical polymerizing compound having one functional group with a charge transport structure, and wherein the outermost layer has an elasticity power not less than 41%.
    Type: Grant
    Filed: May 25, 2005
    Date of Patent: January 6, 2009
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshiki Yanagawa, Hiroshi Tamura, Tetsuro Suzuki, Naohiro Toda, Yoshiaki Kawasaki
  • Publication number: 20080292981
    Abstract: This invention relates to image bearing member and an image forming apparatus that employs the image bearing member. The image bearing member contains an electroconductive substrate; a charge generation layer; a charge transport layer; a cross-linking surface protective layer, and a monomer having one radical polymerizable functional group with a charge transport structure. The cross-linking surface protective layer is formed by curing a monomer having at least three radical polymerizable functional groups without a charge transport structure. For the image bearing member, the ratio of the layer thickness of the cross linking surface protective layer to the layer thickness of the charge transport layer is from 0.7 to 1.3.
    Type: Application
    Filed: February 14, 2008
    Publication date: November 27, 2008
    Inventors: Naohiro Toda, Yoshiki Yanagawa, Takaaki Ikegami, Makoto Yasuda, Takeshi Orito
  • Patent number: 7416823
    Abstract: An electrophotographic photoconductor having at least a photoconductive layer on an electrically conductive support, in which a surface layer of the photoconductive layer can be obtained by curing at least a free-radical-polymerizable monomer having no charge transporting structure, represented by general formula (A) and a one-functional free-radical-polymerizable compound having a charge transporting structure, wherein R71, R72, R73, R74, R75, and R76 are described in the specification.
    Type: Grant
    Filed: January 13, 2005
    Date of Patent: August 26, 2008
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshiki Yanagawa, Hiroshi Ikuno, Hongguo Li, Kazukiyo Nagai, Hiroshi Tamura, Tetsuro Suzuki, Naohiro Toda, Yoshiaki Kawasaki
  • Patent number: 7390600
    Abstract: An object is to provide a latent electrostatic image bearing member that can provide high-quality images for prolonged periods, owing to photosensitive layers and crosslinked surface layers having excellent flaw and wear resistance and appropriate electric properties, image forming method, image forming apparatus and process cartridge that employ latent electrostatic image bearing member respectively. Accordingly, provided is a latent electrostatic image bearing member that comprises a support and at least a photosensitive layer and a crosslinked surface layer disposed on the support, wherein the crosslinked surface layer comprises a reactant from radical polymerizable compounds having three or more functionalities with no charge transport structure and radical polymerizable compounds having one functionality with charge transport structure, and at least two different antioxidants.
    Type: Grant
    Filed: September 2, 2005
    Date of Patent: June 24, 2008
    Assignee: Ricoh Company, Ltd.
    Inventors: Naohiro Toda, Hiroshi Tamura, Yoshiki Yanagawa, Tetsuro Suzuki