Patents by Inventor Ryuta Takeichi

Ryuta Takeichi 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: 6558862
    Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 &mgr;g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.
    Type: Grant
    Filed: March 2, 2001
    Date of Patent: May 6, 2003
    Assignee: Ricoh Company Limited
    Inventors: Narihito Kojima, Ryuta Takeichi, Akiyo Namiki, Hiroshi Nagame, Yohta Sakon
  • Patent number: 6521386
    Abstract: An electrophotographic photoreceptor including an electroconductive substrate and a photoreceptive layer, which is formed overlying the substrate, wherein the photoreceptive layer includes a charge carrier generation layer including a charge carrier generation material and a charge carrier transport layer including a charge carrier transport material, and wherein when an electric field of from 2.5×105 V/cm to 5.5×105 V/cm is applied to the charge carrier transport layer, the relationship, tCTL/&mgr;CTL≦1.5×103 V·s/m, is satisfied, wherein tCTL represents a thickness of the charge carrier transport layer and &mgr;CTL represents a charge mobility of the charge carrier transport layer.
    Type: Grant
    Filed: February 15, 2000
    Date of Patent: February 18, 2003
    Assignee: Ricoh Company Ltd.
    Inventors: Yohta Sakon, Narihito Kojima, Minoru Umeda, Masao Yoshikawa, Hiroshi Nagame, Ryuta Takeichi, Akiyo Namiki
  • Patent number: 6363237
    Abstract: A lubricity-imparting unit for imparting lubricity to a surface of an electrophotographic photoconductor, which is in contact with the surface of the photoconductor, wherein at least a surface of the lubricity-imparting unit which comes into contact with the surface of the photoconductor includes a flexible lubricating material, and has a length at least capable of covering an image formation region of the electrophotographic photoconductor lengthwise. An image formation apparatus and an image formation method using this lubricity-imparting unit are described.
    Type: Grant
    Filed: November 11, 1999
    Date of Patent: March 26, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroshi Nagame, Narihito Kojima, Yohta Sakon, Ryuta Takeichi, Akiyo Nakajima
  • Publication number: 20020034406
    Abstract: An image forming apparatus including a belt guide member fixedly provided at an upstream side of a nip formed between a roller and a transfer roller so the belt guide member protrudes an image bearing belt such that the belt is substantially parallel with a conveying direction of a transfer medium.
    Type: Application
    Filed: September 7, 2001
    Publication date: March 21, 2002
    Applicant: RICOH COMPANY, LTD.
    Inventors: Katsuya Kawagoe, Toshiaki Motohashi, Yuuji Sawai, Shin Kayahara, Ryuta Takeichi, Mitsuru Takahashi, Hiroshi Ono, Hiromi Ogiyama
  • Publication number: 20010031411
    Abstract: An electrophotographic photoreceptor including a photosensitive layer on an electroconductive substrate, wherein nitrate ion is present on the surface of the photosensitive layer in an amount of from 50 to 300 &mgr;g per 1 m2 of the surface of the photosensitive layer when the nitrate ion is determined by an ion chromatographic method. Preferably a material having a fluorine atom and a carbon atom or a fatty acid metal salt such as zinc stearate is further present on the surface of the photosensitive layer such that the F/C ratio is from 0.05 to 0.5 or the Zn/C ratio is from 0.001 to 0.1. An image forming apparatus using the photoreceptor is also provided.
    Type: Application
    Filed: March 2, 2001
    Publication date: October 18, 2001
    Applicant: Ricoh Company Limited
    Inventors: Narihito Kojima, Ryuta Takeichi, Akiyo Namiki, Hiroshi Nagame, Yohta Sakon
  • Patent number: 6160977
    Abstract: In an image forming apparatus of the type sequentially executing charging, exposure, development and image transfer, a device for applying a lubricant to the surface of an image carrier includes a lubricant applying member rotatable in contact with the image carrier for applying, at a position where the lubricant applying member contacts the image carrier, the lubricant to the surface of the image carrier while deforming its contour in accordance with a bite of the surface of the image carrier. A lubricant feeding unit feeds the lubricant to the lubricant applying member and includes a lubricant providing unit having a preselected thickness t. The surface of the image carrier bites into the lubricant applying member by an amount T while the lubricant providing unit bites into the lubricant applying member by an amount t' smaller than the amount T, but substantially equal to or slightly greater than the thickness t.
    Type: Grant
    Filed: November 29, 1999
    Date of Patent: December 12, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Ryuta Takeichi, Akiyo Nakajima, Narihito Kojima, Hiroshi Nagame, Yohta Sakon
  • Patent number: 6118964
    Abstract: A charging or image transfer unit for use in an image formation process including the steps of charging, image formation exposure, image development, image transfer, image fixing and cleaning, for applying an electric field to the surface of an electrophotographic photoconductor by coming into contact therewith, and also for controlling surface properties of the electrophotographic photo-conductor. The unit includes an electric field application member applying the electric field to the surface of the electrophotographic photoconductor and a lubricity-imparting member for controlling a friction coefficient of the surface of the electrophotographic photoconductor wherein the electric field application member includes an electrophotoconductive material and a lubricity-imparting member includes a fluoroplastic material.
    Type: Grant
    Filed: December 10, 1998
    Date of Patent: September 12, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Narihito Kojima, Hiroshi Nagame, Ryuta Takeichi, Yukiko Iwasaki, Akiyo Nakajima, Hiroyuki Fushimi
  • Patent number: 6060205
    Abstract: An image forming apparatus comprising a lubricant supplying device which supplies a lubricant to a rotating image carrier, wherein the lubricant comprises at least one of low molecular weight polytetrafluoroethylene, a fluorine-containing resin including a filler, polytetrafluoroethylene which has been subjected to heat or radiation decomposition treatment, a fluorine-containing resin which has been prepared by a compression molding method, and a porous fluorine-containing resin. The lubricant preferably has a concave portion on the surface thereof contacting the image carrier. The lubricant is preferably disposed so that an acute angle formed by a line parallel to a compression direction of the lubricant, during the compression molding of the lubricant, and a line parallel to a moving direction of the image carrier, is from about 45 to about 90.degree..
    Type: Grant
    Filed: April 19, 1999
    Date of Patent: May 9, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Ryuta Takeichi, Narihito Kojima, Hiroshi Nagame, Yohta Sakon, Akiyo Nakajima
  • Patent number: 6014532
    Abstract: An image forming apparatus capable of adequately adjusting the amount of a low friction agent to be applied to the surface of a photoconductive element in accordance with image quality is disclosed. After preselected initialization, an electrophotographic image forming section records a usual image or a particular image for evaluation on a paper. A toner image formed on the photoconductive element and a toner image transferred from the element to a paper are read. Image data representative of such toner images and the initial image data are compared to see if the read images are defective or not. The low friction agent is applied to the photoconductive element in an amount controlled on the basis of the result of the decision.
    Type: Grant
    Filed: November 3, 1998
    Date of Patent: January 11, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Ryuta Takeichi, Yukiko Iwasaki, Akiyo Nakajima, Hiroshi Nagame, Narihito Kojima, Hiroyuki Fushimi