Patents by Inventor Michihiko Namba

Michihiko Namba 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: 20040131960
    Abstract: An electrophotographic photoconductor has an electroconductive support and a photoconductive layer which is formed thereon and contains at least one resin of a polyurethane resin, a polyester resin, or a polycarbonate resin, each resin having at least a structural unit of formula (1): 1
    Type: Application
    Filed: December 16, 2003
    Publication date: July 8, 2004
    Applicant: RICOH COMPANY, LTD.
    Inventors: Shinichi Kawamura, Kazukiyo Nagai, Tomoyuki Shimada, Chiaki Tanaka, Michihiko Namba
  • Publication number: 20030198881
    Abstract: An electrophotographic photoconductor has an electroconductive support and a photoconductive layer which is formed thereon and contains at least one resin of a polyurethane resin, a polyester resin, or a polycarbonate resin, each resin having at least a structural unit of formula (1): 1
    Type: Application
    Filed: February 12, 2003
    Publication date: October 23, 2003
    Applicant: RICOH COMPANY, LTD.
    Inventors: Shinichi Kawamura, Kazukiyo Nagai, Tomoyuki Shimada, Chiaki Tanaka, Michihiko Namba
  • Patent number: 6596449
    Abstract: An electrophotographic photoreceptor for an electrophotographic image forming apparatus which has a laser diode or a light emitting diode emitting a light having a wavelength of 350 to 500 nm as an image writing light source, wherein the photoreceptor includes a photosensitive layer including a deactivating agent.
    Type: Grant
    Filed: July 5, 2001
    Date of Patent: July 22, 2003
    Assignee: Ricoh Company Limited
    Inventors: Tomoyuki Shimada, Kazukiyo Nagai, Chiaki Tanaka, Michihiko Namba, Shinichi Kawamura
  • Patent number: 6548216
    Abstract: An electrophotographic photoconductor has an electroconductive support and a photoconductive layer which is formed thereon and contains at least one resin of a polyurethane resin, a polyester resin, or a polycarbonate resin, each resin having at least a structural unit of formula (1): wherein R1, R2, R3, a, b, and n are the same as those specified in the specification. An electrophotographic image forming apparatus and method, and a process cartridge employ the above photoconductor.
    Type: Grant
    Filed: March 23, 2001
    Date of Patent: April 15, 2003
    Assignee: Ricoh Company, Ltd.
    Inventors: Shinichi Kawamura, Kazukiyo Nagai, Tomoyuki Shimada, Chiaki Tanaka, Michihiko Namba
  • Patent number: 6544701
    Abstract: To provide a novel reaction product useful as an organic photoconductive material for electrophotographic photoconductors. A product obtainable by reacting (i) a nitrile derivative, (ii) a phthalonitrile derivative or a 1,3-diiminoisoindoline derivative and, if necessary, (iii) a metal or a metal-containing compound.
    Type: Grant
    Filed: February 5, 2002
    Date of Patent: April 8, 2003
    Assignee: Ricoh Company, Ltd.
    Inventors: Kaoru Tadokoro, Masayuki Shoshi, Michihiko Namba, Tomoyuki Shimada, Chiaki Tanaka
  • Patent number: 6524761
    Abstract: A mixture is made of a plurality of different titanyltetraazaporphyrin compounds, each of which is represented by formula (1): wherein A, B, C and D are each independently an unsubstituted or substituted benzene ring or pyridine ring, a substituent thereof being selected from the group consisting of nitro group, cyano group, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxyl group having 1 to 8 carbon atoms, and an aryl group. The above-mentioned mixture is contained in a photoconductive layer of an electrophotographic photoconductor as a photoconductive material.
    Type: Grant
    Filed: July 16, 2001
    Date of Patent: February 25, 2003
    Assignee: Ricoh Company, Ltd.
    Inventors: Tomoyuki Shimada, Masayuki Shoshi, Kaoru Tadokoro, Chiaki Tanaka, Michihiko Namba
  • Publication number: 20030013028
    Abstract: [Problem] To provide a novel reaction product useful as an organic photoconductive material for electrophotographic photoconductors.
    Type: Application
    Filed: February 5, 2002
    Publication date: January 16, 2003
    Applicant: Ricoh Company, Ltd.
    Inventors: Kaoru Tadokoro, Masayuki Shoshi, Michihiko Namba, Tomoyuki Shimada, Chiaki Tanaka
  • Patent number: 6492079
    Abstract: An electrophotographic photoconductor has an electroconductive support, and a charge generation layer and a charge transport layer successively formed on the electroconductive support, the charge transport layer allowing any monochromatic light with a wavelength in a wavelength region of 390 to 460 nm to pass through and exhibiting a fluorescence generation coefficiency of 0.8 or less when irradiated with the monochromatic light. An electrophotographic image forming apparatus and a process cartridge employ the above-mentioned photoconductor.
    Type: Grant
    Filed: March 27, 2001
    Date of Patent: December 10, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Tomoyuki Shimada, Kazukiyo Nagai, Chiaki Tanaka, Michihiko Namba, Shinichi Kawamura
  • Patent number: 6465648
    Abstract: A reaction product useful as an organic photoconductive material for electrophotographic photoconductors is provided, obtainable by reacting (i) a nitrile derivative, (ii) a phthalonitrile derivative or a 1,3-diiminoisoindoline derivative and, if necessary, (iii) a metal or a metal-containing compound.
    Type: Grant
    Filed: June 22, 2000
    Date of Patent: October 15, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Kaoru Tadokoro, Masayuki Shoshi, Michihiko Namba, Tomoyuki Shimada, Chiaki Tanaka
  • Publication number: 20020045117
    Abstract: An electrophotographic photoreceptor for an electrophotographic image forming apparatus which has a laser diode or a light emitting diode emitting a light having a wavelength of 350 to 500 nm as an image writing light source, wherein the photoreceptor includes a photosensitive layer including a deactivating agent.
    Type: Application
    Filed: July 5, 2001
    Publication date: April 18, 2002
    Inventors: Tomoyuki Shimada, Kazukiyo Nagai, Chiaki Tanaka, Michihiko Namba, Shinichi Kawamura
  • Publication number: 20020028400
    Abstract: An electrophotographic photoconductor has an electroconductive support, and a charge generation layer and a charge transport layer successively formed on the electroconductive support, the charge transport layer allowing any monochromatic light with a wavelength in a wavelength region of 390 to 460 nm to pass through and exhibiting a fluorescence generation coefficiency of 0.8 or less when irradiated with the monochromatic light. An electrophotographic image forming apparatus and a process cartridge employ the above-mentioned photoconductor.
    Type: Application
    Filed: March 27, 2001
    Publication date: March 7, 2002
    Applicant: Ricoh Company, Ltd.
    Inventors: Tomoyuki Shimada, Kazukiyo Nagai, Chiaki Tanaka, Michihiko Namba, Shinichi Kawamura
  • Publication number: 20020025483
    Abstract: An electrophotographic photoconductor has an electroconductive support and a photoconductive layer which is formed thereon and contains at least one resin of a polyurethane resin, a polyester resin, or a polycarbonate resin, each resin having at least a structural unit of formula (1): 1
    Type: Application
    Filed: March 23, 2001
    Publication date: February 28, 2002
    Applicant: Ricoh Company, Ltd.
    Inventors: Shinichi Kawamura, Kazukiyo Nagai, Tomoyuki Shimada, Chiaki Tanaka, Michihiko Namba
  • Publication number: 20020007056
    Abstract: A mixture is made of a plurality of different titanyltetraazaporphyrin compounds, each of which is represented by formula (1): 1
    Type: Application
    Filed: July 16, 2001
    Publication date: January 17, 2002
    Applicant: Ricoh Company, Ltd.
    Inventors: Tomoyuki Shimada, Masayuki Shoshi, Kaoru Tadokoro, Chiaki Tanaka, Michihiko Namba
  • Patent number: 6313288
    Abstract: A mixture is made of a plurality of different titanyltetraazaporphyrin compounds, each of which is represented by formula (1): wherein A, B, C and D are each independently an unsubstituted or substituted benzene ring or pyridine ring, a substituent thereof being selected from the group consisting of nitro group, cyano group, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxyl group having 1 to 8 carbon atoms, and an aryl group. The above-mentioned mixture is contained in a photoconductive layer of an electrophotographic photoconductor as a photoconductive material.
    Type: Grant
    Filed: November 17, 1999
    Date of Patent: November 6, 2001
    Assignee: Ricoh Company, Ltd.
    Inventors: Tomoyuki Shimada, Masayuki Shoshi, Kaoru Tadokoro, Chiaki Tanaka, Michihiko Namba
  • Patent number: 6074792
    Abstract: A pigment includes a compound with a tetraazaporphyrin skeleton represented by formula (I): ##STR1## wherein M is a hydrogen atom, or an atom or compound capable of bonding to tetraazaporphyrin through a covalent bond or a coordinate bond; and R.sup.1 to R.sup.8 are each independently a hydrogen atom, a lower alkyl group which may have a substituent, or an aryl group which may have a substituent. In addition, the above-mentioned pigment is used as a charge generation material in an electrophotographic photoconductor comprising an electroconductive support and a photoconductive layer formed thereon.
    Type: Grant
    Filed: July 13, 1998
    Date of Patent: June 13, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Michihiko Namba, Masayuki Shoshi, Kaoru Tadokoro
  • Patent number: 6068956
    Abstract: An electrophotographic photoconductor has an electroconductive support, and a photoconductive layer formed thereon which contains as a charge generation material a pigment including a compound with a tetraazaporphyrin skeleton represented by formula (I): ##STR1## wherein M is a hydrogen atom, or an atom or compound capable of bonding to tetraazaporphyrin through a covalent bond or a coordinate bond; and R.sup.1 to R.sup.4 are each independently a hydrogen atom, a lower alkyl group which may have a substituent, or an aryl group which may have a substituent.
    Type: Grant
    Filed: April 8, 1999
    Date of Patent: May 30, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Michihiko Namba, Masayuki Shoshi, Kaoru Tadokoro
  • Patent number: 5942362
    Abstract: An electrophotographic photoconductor has an electroconductive support and a photoconductive layer provided thereon, containing at least one phenol compound of formula (1): ##STR1## wherein R.sup.1 to R.sup.4 and R.sup.11 to R.sup.14 are each independently a hydrogen atom, an alkyl group which may have a substituent, an alkoxyl group which may have a substituent, an alkoxycarbonyl group which may have a substituent, an aryl group which may have a substituent, nitro group, cyano group or a halogen atom; and Y is ##STR2## in which R is a hydrogen atom, an alkyl group which may have a substituent, an alkoxyl group which may have a substituent, an alkoxycarbonyl group which may have a substituent, an aryl group which may have a substituent, nitro group, cyano group, hydroxyl group or a halogen atom, and n is an integer of 0 to 5, or --(CH.dbd.CH).sub.x --, in which x is an integer of 0 to 5.
    Type: Grant
    Filed: October 30, 1997
    Date of Patent: August 24, 1999
    Assignee: Ricoh Company, Ltd.
    Inventors: Kaoru Tadokoro, Masayuki Shoshi, Michihiko Namba