Patents by Inventor Mitsuaki Hirose

Mitsuaki Hirose 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: 12353166
    Abstract: A toner is provided. The toner comprises toner base particles, resin particles adhered to surfaces of the toner base particles, and an external additive adhered to the surfaces of the toner base particles. The toner base particles each comprising a binder resin, a colorant, and a wax. The toner has a storage elastic modulus G? of 4.0×105 or less at 70° C. An embedment degree of the external additive is from 15% to 40%, as the embedment degree is measured by stirring 10 g of the toner and 20 g of a carrier in a 50-mL vial at 67 Hz for 60 minutes using a rocking mill.
    Type: Grant
    Filed: August 16, 2021
    Date of Patent: July 8, 2025
    Assignee: Ricoh Company, Ltd.
    Inventors: Daisuke Inoue, Mitsuaki Hirose, Yohichi Kitagawa, Masayuki Ukigaya, Kenji Komito, Hiroshi Yamada
  • Publication number: 20230280670
    Abstract: [Summary] An object of the present invention is to provide a toner that has both low-temperature fixability and heat-resistant storage stability, suppresses contamination of cleaning parts and photoconductors, and has excellent charging stability. [Tasks] A toner includes toner based particles containing a binder resin, a colorant, and a wax; and fine resin particles and an inorganic external additive that are present on a surface of the toner based particles, wherein a coverage of the fine resin particles is in a range from 30% to 70%, and wherein the inorganic external additive covers a surface of oxide of a metal element with hydroxide of a metal element.
    Type: Application
    Filed: February 28, 2023
    Publication date: September 7, 2023
    Applicant: Ricoh Company, Ltd.
    Inventors: Tsukiko TAKAHASHI, Mitsuaki Hirose, Yohichi Kitagawa, Suzuka Karato, Hiroshi Yamada
  • Publication number: 20230040461
    Abstract: A toner includes: toner base particles including a binder resin, a colorant, an inorganic filler, and a release agent; and an external additive. An average circularity of the toner is 0.974 or more but 0.985 or less. A surface roughness parameter Sz of a surface of the toner is 200 nm or more but 500 nm or less, the surface roughness parameter Sz being measured with an atomic force microscope (AFM).
    Type: Application
    Filed: July 25, 2022
    Publication date: February 9, 2023
    Applicant: Ricoh Company, Ltd.
    Inventors: Daisuke Inoue, Mitsuaki Hirose, Yohichi Kitagawa, Tsukiko Takahashi, Kenji Komito, Akihiko Moki
  • Publication number: 20220155699
    Abstract: A toner is provided. The toner comprises toner particles each comprising a toner base particle and an external additive. The toner base particle comprises a binder resin and a colorant. The toner satisfies the following conditions (a) and (b): (a) an average surface roughness Ra [nm] of the toner particles, detected by a scanning probe microscope analyzer, satisfies the following formula (1): 10<Ra<200??Formula (1); and (b) the external additive comprises coalesced particles being non-spherical secondary particles in which primary particles are coalesced with each other, the coalesced particles having a number average particle diameter of 50 nm or more.
    Type: Application
    Filed: October 14, 2021
    Publication date: May 19, 2022
    Applicant: Ricoh Company, Ltd.
    Inventors: Yohichi KITAGAWA, Kenji Komito, Masayuki Ukigaya, Mitsuaki Hirose, Daisuke Inoue
  • Publication number: 20220057725
    Abstract: A toner is provided. The toner comprises toner base particles, resin particles adhered to surfaces of the toner base particles, and an external additive adhered to the surfaces of the toner base particles. The toner base particles each comprising a binder resin, a colorant, and a wax. The toner has a storage elastic modulus G? of 4.0×105 or less at 70° C. An embedment degree of the external additive is from 15% to 40%, as the embedment degree is measured by stirring 10 g of the toner and 20 g of a carrier in a 50-mL vial at 67 Hz for 60 minutes using a rocking mill.
    Type: Application
    Filed: August 16, 2021
    Publication date: February 24, 2022
    Applicant: Ricoh Company, Ltd.
    Inventors: Daisuke INOUE, Mitsuaki Hirose, Yohichi Kitagawa, Masayuki Ukigaya, Kenji Komito, Hiroshi Yamada
  • Patent number: 11016403
    Abstract: An electrophotographic photoconductor is provided that includes a conductive substrate, an undercoat layer overlying the conductive substrate, and a photosensitive layer overlying the undercoat layer. The undercoat layer contains zinc oxide particles and a binder resin and has a volume resistivity of 0.03×106 ?·cm or less in an electrical field of 5 V/?m at a temperature of 23 degrees C. and a relative humidity of 55%. The photosensitive layer contains a compound represented by the following general formula (1): where each of R1 to R3 independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms.
    Type: Grant
    Filed: January 15, 2020
    Date of Patent: May 25, 2021
    Assignee: Ricoh Company, Ltd.
    Inventors: Hideki Nakamura, Tadayoshi Uchida, Shuya Sugimoto, Mitsuaki Hirose, Noboru Toriu, Kaori Harada
  • Publication number: 20200233325
    Abstract: An electrophotographic photoconductor is provided that includes a conductive substrate, an undercoat layer overlying the conductive substrate, and a photosensitive layer overlying the undercoat layer. The undercoat layer contains zinc oxide particles and a binder resin and has a volume resistivity of 0.03×106 ?·cm or less in an electrical field of 5 V/?m at a temperature of 23 degrees C. and a relative humidity of 55%. The photosensitive layer contains a compound represented by the following general formula (1): where each of R1 to R3 independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms.
    Type: Application
    Filed: January 15, 2020
    Publication date: July 23, 2020
    Inventors: Hideki Nakamura, Tadayoshi Uchida, Shuya Sugimoto, Mitsuaki Hirose, Noboru Toriu, Kaori Harada
  • Patent number: 10466604
    Abstract: Provided is an electrophotographic photoconductor including: a conductive support; an undercoat layer; and a photoconductive layer, wherein the undercoat layer and the photoconductive layer are provided over the conductive support in the order of reciting, wherein the undercoat layer contains at least metal oxide particles, a binder, and a salicylic acid derivative such as 4-methylsalicylic acid, wherein the metal oxide particles have a volume resistivity of 1×105 ?·cm or higher but 1×108 ?·cm or lower, wherein the undercoat layer has a volume resistivity of 0.001×106 ?·cm or higher but 0.02×106 ?·cm or lower, and wherein the undercoat layer has a thickness of 2 micrometers or greater but 20 micrometers or less.
    Type: Grant
    Filed: July 2, 2018
    Date of Patent: November 5, 2019
    Assignee: Ricoh Company, Ltd.
    Inventors: Tetsuya Toshine, Mitsuaki Hirose, Tomoharu Asano
  • Publication number: 20190011845
    Abstract: Provided is an electrophotographic photoconductor including: a conductive support; an undercoat layer; and a photoconductive layer, wherein the undercoat layer and the photoconductive layer are provided over the conductive support in the order of reciting, wherein the undercoat layer contains at least metal oxide particles, a binder, and a salicylic acid derivative such as 4-methylsalicylic acid, wherein the metal oxide particles have a volume resistivity of 1×105 ?·cm or higher but 1×108 ?·cm or lower, wherein the undercoat layer has a volume resistivity of 0.001×106 ?·cm or higher but 0.02×106 ?·cm or lower, and wherein the undercoat layer has a thickness of 2 micrometers or greater but 20 micrometers or less.
    Type: Application
    Filed: July 2, 2018
    Publication date: January 10, 2019
    Inventors: Tetsuya TOSHINE, Mitsuaki Hirose, Tomoharu Asano
  • Patent number: 10073363
    Abstract: A photoconductor is provided. The photoconductor includes a cylindrical conductive support, a water-repellent resin film, a coating film, and a flange. The cylindrical conductive support has an end part having an inner circumferential surface having a surface roughness Rz of from 3 to 10 ?m. The water-repellent resin film is on the inner circumferential surface of the end part of the cylindrical conductive support. The coating film is on an outer circumferential surface of the cylindrical conductive support. The flange has a cylindrical fitting part having an outer circumferential surface secured to the inner circumferential surface of the end part of the cylindrical conductive support.
    Type: Grant
    Filed: January 3, 2017
    Date of Patent: September 11, 2018
    Assignee: Ricoh Company, Ltd.
    Inventors: Mitsuaki Hirose, Daisuke Kubo, Hiroshi Hashiguchi
  • Patent number: 9146483
    Abstract: In a photoreceptor including an electroconductive substrate; a photosensitive layer; and a protective layer, the protective layer includes a crosslinked resin having a residual group of a polycarboxylic acid compound and a group having the below-mentioned formula (10), and at least one of a compound having the below-mentioned formula (2) and a compound having the below-mentioned formula (3). wherein each of R5 and R6 independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms. wherein each of R7 and R8 independently represents a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and Z1 represents a vinylene group, a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a 2,5-thiophenediyl group.
    Type: Grant
    Filed: February 20, 2013
    Date of Patent: September 29, 2015
    Assignee: Ricoh Company, Ltd.
    Inventors: Mitsuaki Hirose, Akihiro Sugino, Noboru Toriu, Keisuke Shimoyama, Tomoharu Asano
  • Patent number: 9031491
    Abstract: An image forming apparatus, including a photoreceptor; a charger; an irradiator; an image developer; a transferer; a fixer; and a cleaning blade formed of a strip-shaped elastic blade, removing a powder from the surface of the photoreceptor passing an edge line of the blade while contacting thereto, wherein the photoreceptor includes a crosslinked resin surface layer formed of at least one of an acrylic resin and a methacrylic resin, and the cleaning blade includes a contact point with the photoreceptor, including a substrate; a mixed layer formed of at least one of an acrylic resin and a methacrylic resin, located at the surface of the substrate; and a surface layer formed of at least one of an acrylic resin and a methacrylic resin, located on the surface of the substrate.
    Type: Grant
    Filed: February 12, 2013
    Date of Patent: May 12, 2015
    Assignee: Ricoh Company, Ltd.
    Inventors: Tomoharu Asano, Hideo Nakamori, Akihiro Sugino, Noboru Toriu, Keisuke Shimoyama, Mitsuaki Hirose, Yohta Sakon, Masahiro Ohmori
  • Patent number: 8927183
    Abstract: A photoreceptor including an electroconductive substrate; a photosensitive layer, which is located overlying the electroconductive substrate and which includes a charge generation material, a charge transport material having no radical polymerizability, a binder resin having no radical polymerizability, and a crosslinked polymer including a unit obtained from a first radically polymerizable monomer having three or more functional groups and no charge transport structure and a unit obtained from a second radically polymerizable monomer having a charge transport structure; and an outermost layer, which is located on the photosensitive layer and which includes a crosslinked polymer including a unit obtained from a third radically polymerizable monomer having three or more functional groups and no charge transport structure and a unit obtained from a fourth radically polymerizable monomer having a charge transport structure. An image forming method and apparatus, and a process cartridge using the photoreceptor.
    Type: Grant
    Filed: May 28, 2008
    Date of Patent: January 6, 2015
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshiaki Kawasaki, Akihiro Sugino, Mitsuaki Hirose
  • Patent number: 8647798
    Abstract: A photoreceptor including an electroconductive substrate; a photosensitive layer on the electroconductive substrate; and a protection layer on the photosensitive layer, wherein the protection layer includes a radical polymerizable compound having three or more radical polymerizable groups without a charge transportable group, a monofunctional radical polymerizable compound having a specific charge transportable group and a non-radical polymerizable compound having a specific charge transportable group.
    Type: Grant
    Filed: July 24, 2012
    Date of Patent: February 11, 2014
    Assignee: Ricoh Company, Ltd.
    Inventors: Tomoharu Asano, Hiroshi Ikuno, Akihiro Sugino, Hideo Nakamori, Mitsuaki Hirose
  • Publication number: 20130330104
    Abstract: A photoreceptor includes an electroconductive substrate, and a laminate structure formed of at least a charge generating layer and a charge transport layer and provided overlying the electroconductive substrate, wherein the charge transport layer contains a charge transport material, a compound represented by the following formula 1 and a compound represented by the following formula 2: in the formula 1, R1 and R2 each independently represent substituted or non-substituted alkyl groups or aromatic hydrocarbon groups and one of R1 and R2 represents a substituted or non-substituted aromatic hydrocarbon group, R1 and R2 bonded to the same nitrogen atom may be bonded together to form a substituted or non-substituted nitrogen-containing heterocyclic group, and Ar represents a substituted or non-substituted hydrocarbon group; in the formula 2, R3 and R4 each independently represent substituted or non-substituted alkyl groups or aromatic hydrocarbon groups.
    Type: Application
    Filed: May 31, 2013
    Publication date: December 12, 2013
    Applicant: RICOH COMPANY, LTD.
    Inventors: Keisuke Shimoyama, Akihiro Sugino, Mitsuaki Hirose, Tomoharu Asano, Noboru Toriu, Hideo Nakamori
  • Publication number: 20130251401
    Abstract: An image forming apparatus, including a photoreceptor; a charger; an irradiator; an image developer; a transferer; a fixer; and a cleaning blade formed of a strip-shaped elastic blade, removing a powder from the surface of the photoreceptor passing an edge line of the blade while contacting thereto, wherein the photoreceptor includes a crosslinked resin surface layer formed of at least one of an acrylic resin and a methacrylic resin, and the cleaning blade includes a contact point with the photoreceptor, including a substrate; a mixed layer formed of at least one of an acrylic resin and a methacrylic resin, located at the surface of the substrate; and a surface layer formed of at least one of an acrylic resin and a methacrylic resin, located on the surface of the substrate.
    Type: Application
    Filed: February 12, 2013
    Publication date: September 26, 2013
    Applicant: RICOH COMPANY, LTD.
    Inventors: Tomoharu Asano, Hideo Nakamori, Akihiro Sugino, Noboru Toriu, Keisuke Shimoyama, Mitsuaki Hirose, Yohta Sakon, Masahiro Ohmori
  • Patent number: 8507163
    Abstract: A method of manufacturing an image bearing member including forming a charge generation layer overlying an electroconductive substrate, forming a charge transport layer overlying the charge generation layer, the charge transport layer including a charge transport material having a molecular weight of from 600 to 900 and a binder resin, and forming a protection layer overlying the charge transport layer by applying a liquid application containing a polymerizable compound having a charge transport structure, a polymerizable compound having no charge transport structure, a filler, a polycarboxylic acid compound, and cyclopentanone and curing the polymerizable compound having a charge transport structure, and the polymerizable compound having no charge transport structure.
    Type: Grant
    Filed: December 11, 2009
    Date of Patent: August 13, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Nozomu Tamoto, Hideo Nakamori, Mitsuaki Hirose
  • Patent number: 8486595
    Abstract: An image bearing member including an electroconductive substrate, a photosensitive layer overlying the electroconductive substrate, and a protection layer overlying the photosensitive layer, the photosensitive layer containing a diamine compound represented by the chemical structure 1, more of the diamine compound being disposed on the photosensitive layer side than the surface side relative to the midpoint in a depth direction of the protection layer: where X represents a substituted or non-substituted arylene group, or a compound represented by a chemical structure 2: where R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, where A1, A2, A3, and A4 independently represent an alkyl group having 1 to 4 carbon atoms, a substituted or non-substituted aryl group, or —CH2(CH2)mZ, where Z represents a substituted or non-substituted aryl group, a substituted or non-substituted cycloalkyl group, and a substituted or non-substituted
    Type: Grant
    Filed: September 10, 2010
    Date of Patent: July 16, 2013
    Assignee: Ricoh Company, Ltd.
    Inventors: Nozomu Tamoto, Mitsuaki Hirose, Hideo Nakamori
  • Publication number: 20130059242
    Abstract: A photoreceptor including an electroconductive substrate; a photosensitive layer on the electroconductive substrate; and a protection layer on the photosensitive layer, wherein the protection layer includes a radical polymerizable compound having three or more radical polymerizable groups without a charge transportable group, a monofunctional radical polymerizable compound having a specific charge transportable group and a non-radical polymerizable compound having a specific charge transportable group.
    Type: Application
    Filed: July 24, 2012
    Publication date: March 7, 2013
    Inventors: Tomoharu Asano, Hiroshi Ikuno, Akihiro Sugino, Hideo Nakamori, Mitsuaki Hirose
  • Publication number: 20130022902
    Abstract: An electrophotographic photoreceptor including an electroconductive substrate; a charge generation layer located overlying the electroconductive substrate; a charge transport layer located overlying the charge generation layer; and an outermost layer located overlying the charge transport layer. The charge transport layer includes a positive hole transport material having the following formula (1): wherein each of R1 to R26 independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxyl group having 1 to 4 carbon atoms, and a compound having the following formula (2): wherein each of R27 and R28 independently represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
    Type: Application
    Filed: July 13, 2012
    Publication date: January 24, 2013
    Inventors: Keisuke Shimoyama, Hideo Nakamori, Noboru Toriu, Mitsuaki Hirose, Tomoharu Asano