Patents by Inventor Hiromi Tada

Hiromi Tada 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: 8568945
    Abstract: An electrophotographic photoreceptor, including a charge generation layer and a charge transport layer on an electroconductive substrate, wherein the charge generation layer includes titanylphthalocyanine and a binder resin which is a crosslinked material of a resin comprising a polyvinylbutyrat site having the following formula (1) and an isocyanate compound having the following formula (2): wherein R1 and R2 independently represent an alkyl group having 1 to 3 carbon atoms; k, l, m and n represent composition ratios and k+1 is from 0.60 to 0.80, wherein k or 1 may be 0, m is from 0.02 to 0.03, and n is from 0.20 to 0.40; wherein A represents a substituted or unsubstituted organic group having 2 to 4 valences; and O represents an integer of from 2 to 4.
    Type: Grant
    Filed: November 25, 2009
    Date of Patent: October 29, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiromi Tada, Naohiro Toda, Yuuji Tanaka, Norio Nagayama, Yoshinori Inaba, Takafumi Iwamoto
  • Patent number: 8206880
    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: Grant
    Filed: June 2, 2010
    Date of Patent: June 26, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiromi Tada, Masafumi Ohta, Tatsuya Niimi, Norio Nagayama, Yoshiki Yanagawa, Yuuji Tanaka
  • Patent number: 8207312
    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: Grant
    Filed: July 7, 2009
    Date of Patent: June 26, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Masafumi Ohta, Hiromi Tada, Yoshiki Yanagawa
  • Patent number: 8178266
    Abstract: An electrophotographic photoreceptor is provided that contains a conductive substrate, an undercoat layer, a charge generation layer, and a charge transport layer, wherein the under coat layer contains a binder resin and multiple inorganic pigments each having different average primary particle diameters in a total amount of from 75 to 86% by weight, the charge generation layer contains a binder resin and a titanyl phthalocyanine pigment having a specific X-ray diffraction spectrum in an amount of from 70 to 85% by weight, the charge transport layer comprises a specific distyryl compound, and the following formulae (2-1) to (2-3) are satisfied: 0.2?(D(F2)/D(G))?0.5??(2-1) 0.2?D(F1)??(2-2) D(F2)?D(F1)??(2-3) wherein D(F1) (?m) and D(F2) (?m) represent average primary particle diameters of the largest and smallest inorganic pigments, respectively, and D(G) (?m) represents an average primary particle diameter of the titanyl phthalocyanine pigment.
    Type: Grant
    Filed: June 23, 2009
    Date of Patent: May 15, 2012
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiromi Tada, Nozomu Tamoto, Tomoyuki Shimada, Takafumi Iwamoto
  • Patent number: 7955768
    Abstract: There is provided an electrophotographic photoconductor containing a conductive substrate, and a photosensitive layer, disposed thereon, containing a charge transporting material having a triarylamine structure represented by General Formula 1, and wherein the photosensitive layer satisfies Mathematical Formula 1 when peak heights in raman scattering spectra of the triarylamine structure are measured at a wavenumber of 1,324±2 cm?1 by a confocal raman spectroscopy using z-polarized light: where Ar1, Ar2, and Ar3 are substituted or unsubstituted aromatic hydrocarbon groups, and Ar1 and Ar2, Ar2 and Ar3, and Ar3 and Ar1 are optionally combined to form heterocyclic rings, respectively, ?=I(inside)/I(surface)?1.
    Type: Grant
    Filed: September 10, 2007
    Date of Patent: June 7, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiromi Tada, Nozomu Tamoto, Katsuichi Ohta
  • 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: 20100129112
    Abstract: An electrophotographic photoreceptor, including a charge generation layer and a charge transport layer on an electroconductive substrate, wherein the charge generation layer includes titanylphthalocyanine and a binder resin which is a crosslinked material of a resin comprising a polyvinylbutyral site having the following formula (1) and an isocyanate compound having the following formula (2): wherein R1 and R2 independently represent an alkyl group having 1 to 3 carbon atoms; k, l, m and n represent composition ratios and k+l is from 0.60 to 0.80, wherein k or l may be 0, m is from 0.02 to 0.03, and n is from 0.20 to 0.40; wherein A represents a substituted or unsubstituted organic group having 2 to 4 valences; and O represents an integer of from 2 to 4.
    Type: Application
    Filed: November 25, 2009
    Publication date: May 27, 2010
    Applicant: RICOH COMPANY, LTD.
    Inventors: Hiromi TADA, Naohiro TODA, Yuuji TANAKA, Norio NAGAYAMA, Yoshinori INABA, Takafumi IWAMOTO
  • 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
  • Publication number: 20090324281
    Abstract: An electrophotographic photoreceptor is provided that contains a conductive substrate, an undercoat layer, a charge generation layer, and a charge transport layer, wherein the under coat layer contains a binder resin and multiple inorganic pigments each having different average primary particle diameters in a total amount of from 75 to 86% by weight, the charge generation layer contains a binder resin and a titanyl phthalocyanine pigment having a specific X-ray diffraction spectrum in an amount of from 70 to 85% by weight, the charge transport layer comprises a specific distyryl compound, and the following formulae (2-1) to (2-3) are satisfied: 0.2?(D(F2)/D(G))?0.5??(2-1) 0.2?D(F1)??(2-2) D(F2)?D(F1)??(2-3) wherein D(F1) (?m) and D(F2) (?m) represent average primary particle diameters of the largest and smallest inorganic pigments, respectively, and D(G) (?m) represents an average primary particle diameter of the titanyl phthalocyanine pigment.
    Type: Application
    Filed: June 23, 2009
    Publication date: December 31, 2009
    Applicant: RICOH COMPANY, LTD.
    Inventors: Hiromi Tada, Nozomu Tamoto, Tomoyuki Shimada, Takafumi Iwamoto
  • Publication number: 20090185821
    Abstract: An electrophotographic photoreceptor including a conductive substrate; a charge generation layer comprising a metal phthalocyanine pigment as a charge generation material, located overlying the conductive substrate; a charge transport layer comprising a charge transport material having a triarylamine structure, located overlying the charge generation layer; and a cross-linked charge transport layer formed by hardening a radical-polymerizable monomer having no charge transport structure and a radical-polymerizable compound having a charge transport structure, located overlying the charge transport layer. The electrophotographic photoreceptor satisfies the following equations (1) and (2): ?0.16?Ip(T)?Ip(G)?0.07 ??(1) 0.07<Ip(O)?Ip(G)?0.33 ??(2) wherein Ip(G), Ip(T), and Ip(O) represent ionization potentials of the charge generation layer, the charge transport layer, and the cross-linked charge transport layer, respectively.
    Type: Application
    Filed: January 12, 2009
    Publication date: July 23, 2009
    Applicant: RICOH COMPANY, LTD
    Inventors: Takafumi Iwamoto, Nozomu Tamoto, Hiromi Tada
  • Publication number: 20090180788
    Abstract: An image forming apparatus including an image bearing member bearing an electrostatic latent image thereon, a charging device charging the image bearing member, a light irradiating device irradiating the charged image bearing member with light to form the electrostatic latent image, and a developing device developing the electrostatic latent image to form a toner image, wherein the charging time determined by dividing the width of a charging area charged by the charging device in units of mm by the linear velocity of the image bearing member in units of mm/msec is not shorter than the transit time of the image bearing member. The transit time is defined as the time at which an inflection point is firstly observed in a curve showing relationship of the interval between light irradiation and measurement of potential of an irradiated portion with the potential of the irradiated portion, when the interval is shortened.
    Type: Application
    Filed: January 9, 2009
    Publication date: July 16, 2009
    Applicant: RICOH COMPANY, LTD.
    Inventors: Nozomu Tamoto, Hiromi Tada, Takafumi Iwamoto, Yoshinori Inaba
  • Publication number: 20090035017
    Abstract: There is provided an electrophotographic photoconductor containing a conductive substrate, and a photosensitive layer, disposed thereon, containing a charge transporting material having a triarylamine structure represented by General Formula 1, and wherein the photosensitive layer satisfies Mathematical Formula 1 when peak heights in raman scattering spectra of the triarylamine structure are measured at a wavenumber of 1,324±2 cm?1 by a confocal raman spectroscopy using z-polarized light: where Ar1, Ar2, and Ar3 are substituted or unsubstituted aromatic hydrocarbon groups, and Ar1 and Ar2, Ar2 and Ar3, and Ar3 and Ar1 are optionally combined to form heterocyclic rings, respectively, ?=I(inside)/I(surface)?1.
    Type: Application
    Filed: September 10, 2007
    Publication date: February 5, 2009
    Inventors: Hiromi TADA, Nozomu TAMOTO, Katsuichi OHTA
  • Publication number: 20080227007
    Abstract: An image forming apparatus including an image bearing member, a charger, an irradiator, and a developing device, wherein the relationships T1?T2 and T2=W/V are satisfied, wherein T1 (msec) represents a real transit time, defined as a value on X-axis of a first flection point, at which a surface potential (Y) of the image bearing member firstly rises up when a time (X) between irradiating the image bearing member and measuring the surface potential of the irradiated portion thereof is shortened, in a graph showing a relationship between X and Y; T2 (msec) represents a charging time; W (mm) represents a charging width of the charger; and V (mm/msec) represents a linear velocity of the image bearing member.
    Type: Application
    Filed: March 7, 2008
    Publication date: September 18, 2008
    Inventors: Nozomu Tamoto, Hiromi Tada, Yoshinori Inaba, Katsuichi Ohta
  • Publication number: 20080102391
    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: Application
    Filed: October 29, 2007
    Publication date: May 1, 2008
    Inventors: Yoshiki YANAGAWA, Michio Kimura, Nozomu Tamoto, Hiromi Tada, Tetsuya Toshine, Tomoyuki Shimada, Chiaki Tanaka
  • Publication number: 20080063962
    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: Application
    Filed: September 5, 2007
    Publication date: March 13, 2008
    Inventors: Tetsuya TOSHINE, Chiaki Tanaka, Michio Kimura, Tomoyuki Shimada, Nozomu Tamoto, Yoshiki Yanagawa, Hiromi Tada
  • Publication number: 20070194280
    Abstract: A novel UV-excited aluminate phosphor having a homogeneous composition and capable of emitting a strong fluorescence has been developed. A phosphor of the present invention comprises aluminate and other metal components which are combined or doped to aluminate, and is represented by a general composition formula: 7(Sr1-xEux)O.yAl2O3, wherein 0<x?0.5 and 1?y?36. A method for efficiently producing the phosphor of the present invention is also disclosed.
    Type: Application
    Filed: March 14, 2005
    Publication date: August 23, 2007
    Inventors: Hidetoshi Saitoh, Hiromi Tada, Nobuyoshi Nambu, Atsushi Nakamura, Hiroshi Ito
  • Publication number: 20050012114
    Abstract: An up-drain type MOSFET device is formed in a limited n+ diffusion region used for an up-drain structure with the reduction of increase in a chip area which would otherwise be required for such device. Trench 112 is made separately from device regions provided in n?-type exitaxial layer 101. Trench 112 reaches to n+ implanted layer 111 while deeply diffused n+ region 110 is formed along a sidewall of trench 112 by applying slant implantation thereby to form an up-drain structure.
    Type: Application
    Filed: June 4, 2004
    Publication date: January 20, 2005
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Hiromi Tada, Yoshiaki Aizawa, Toshimitsu Kato
  • Publication number: 20030230777
    Abstract: The MOSFET according to the embodiment of the present invention has an n− type layer 3 formed on the support substrate 1 via a first insulating layer 2. In the active layer 3, an n+ type drain layer 7 and a p type base layer 5 are formed at portions away from each other. An n+ type source layer 6 is formed in a surface region of the base layer 5. A trench gate is formed across the source layer 6, the base layer 5 and the active layer 3. A part of the side wall of the trench gate 10 is in contact with the base layer 5 and the source layer 6 via a second insulating layer 8.
    Type: Application
    Filed: April 4, 2003
    Publication date: December 18, 2003
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Toshimitsu Kato, Yoshiaki Aizawa, Hiromi Tada