Patents by Inventor Yuji Nagatomo

Yuji Nagatomo 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: 20130058670
    Abstract: An image developing device includes a developer supporting body; a first conveyance path in which a first conveyance member is arranged; a second conveyance path in which a second conveyance member is arranged; and a partition member that partitions the first conveyance path and the second conveyance path and that has a first communication port and a second communication port. The first communication path and the second communication path communicates with each other through the first communication port and the second communication port. The image developing device includes a developer amount detection unit that includes an optical detection unit arranged in the second conveyance path and that optically detects an amount of the developer in the image forming device. The developer is caused to accumulate in the vicinity of the developer amount detection unit.
    Type: Application
    Filed: March 5, 2012
    Publication date: March 7, 2013
    Inventors: Naoki Nakatake, Tomohiro Kubota, Shoh Tsuritani, Yuji Nagatomo, Yasuhide Matsuno, Hiroaki Katoh, Tomoya Adachi, Rumi Miyazaki, Takafumi Miyazaki, Takeshi Yamashita, Kyoko Abe, Yasuhiro Fujiwara, Takahiro Sanada
  • Patent number: 8354164
    Abstract: A semiconductive member including an alkali metal salt having the formula (M)n.X in a surface layer thereof. M represents Na+, K+, or Li+; X represents Cl?, Br?, I?, F?, CH3COO?, CF3COO?, CH(COOH)CHCOO?, (CHCOO?)2, CH2(COOH)CH2COO?, (CH2COO?)2, (HOOC)Ar(COO?), Ar(COO?)2, (HOOC)2Ar(COO?), (HOOC)Ar(COO?)2, Ar(COO?)3, (HOOC)3Ar(COO?), (HOOC)2Ar(COO?)2, (HOOC)Ar(COO?)3, Ar(COO?)4, Ar—SO3?, Ar(SO3?)2, an oligomer or a polymer having an acrylic acid anion unit, or an oligomer or a polymer having an methacrylic acid anion unit; Ar represents a benzene ring, a naphthalene ring, or a biphenyl ring; and n is a numeral equivalent to the anionic valence of X.
    Type: Grant
    Filed: November 20, 2009
    Date of Patent: January 15, 2013
    Assignee: Ricoh Company, Limited
    Inventors: Chiyoshi Nozaki, Tetsumaru Fujita, Shintaro Yamada, Yuji Nagatomo, Shin Murayama, Manabu Hamada, Yoshimichi Ishikawa
  • Publication number: 20120045254
    Abstract: A developer regulator to restrict an amount of a developer, including a base portion; an intermediate portion continuous with the base portion, the intermediate portion having a flat area on one face, the flat area having a roughened surface; and a distal end continuous with the intermediate portion, the distal end being bent relative to the base portion in a direction opposite the one face in which the flat area is formed.
    Type: Application
    Filed: August 15, 2011
    Publication date: February 23, 2012
    Inventors: Ryuji INOUE, Yuji Nagatomo, Yasuhide Matsuno
  • Patent number: 7907871
    Abstract: An image forming apparatus that is more capable of preventing the occurrence of image quality deterioration caused by defective charging of a photoreceptor than the conventional one. As a charging device, there is used a member which has: a conductive sheet that causes the surface thereof applied with a predetermined bias to abut against the surface of the photoreceptor after passing through a primary transfer nip obtained by abutment between the photoreceptor and an intermediate transfer belt and before entering a development step performed by a developing device; a conductive brush member that applies a predetermined bias to the surface of the photoreceptor obtained after passing through the position of abutment with the sheet and before entering the development step; and a charging roller that uniformly charges the surface of the photoreceptor after passing through the position of abutment with the brush and before entering the development step.
    Type: Grant
    Filed: December 12, 2007
    Date of Patent: March 15, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Patent number: 7903993
    Abstract: An image forming apparatus capable of maintaining cleaning performance of a cleaning brush and downsizing the apparatus main body. Transfer residual toner accumulated on the cleaning brush is transferred onto a photoreceptor by an electrostatic force, hence the cleaning brush becomes clean and the cleaning performance thereof improves. Therefore, the photoreceptor and a charging roller can be cleaned well by the cleaning brush over a long period of time, and the photoreceptor can be charged well by the charging roller over a long period of time. Moreover, because the transfer residual toner that is transferred from the cleaning brush onto the photoreceptor is recovered by a developing device, it is not necessary to provide the apparatus main body with a toner recovery portion that is specially designed for recovering the transfer residual toner, hence the apparatus main body can be downsized.
    Type: Grant
    Filed: January 10, 2008
    Date of Patent: March 8, 2011
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Patent number: 7822356
    Abstract: The present invention provides an image forming apparatus in which the cleaning performance of a cleaning brush is preserved over time while affording a smaller apparatus main body. During a print job, toner recovered from a charging roller to a cleaning brush is transferred from the cleaning brush to a cleaning auxiliary roller, thereby preventing excessive accumulation of toner in the cleaning brush. During non print job times, toner accumulated in the cleaning brush is transferred to the charging roller directly and via the cleaning auxiliary roller, whereby the cleaning brush becomes clean while preserving its cleaning performance. Also, toner transferred to the charging roller is transferred to a photosensitive unit is recovered into a developing device, which does away with the need for a dedicated recovery toner holding portion for recovering residual toner, thereby reducing the size of the apparatus main body.
    Type: Grant
    Filed: January 25, 2008
    Date of Patent: October 26, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Patent number: 7796912
    Abstract: An image forming apparatus includes: an image carrying member having a movable surface; a charging device including a rotatable charging member which is supplied with a voltage including a direct voltage superimposed with an alternating voltage, and which contacts and charges the image carrying member; an electrostatic latent image forming device for forming an electrostatic latent image on the image carrying member; and a development device for developing the electrostatic latent image. The frequency of the alternating voltage is lower in a non-image forming area than in an image forming area. In the non-image forming area, the image carrying member is charged to a surface potential having a waveform shape in accordance with the alternating voltage, and the potential difference between the surface potential and the voltage applied to the charging member generates an electric field which moves toner adhering to the charging member to the image carrying member.
    Type: Grant
    Filed: January 31, 2008
    Date of Patent: September 14, 2010
    Assignee: Ricoh Company Limited
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Patent number: 7796935
    Abstract: A process cartridge includes a latent image carrier, a charging unit, a latent image forming unit, a developing unit, a transfer unit, a rotary brush contacting a curved surface of the latent image carrier to form a nip, and a brush housing including a first tip and a second tip, covering the rotary brush such that a place where the rotary brush contacts the latent image carrier is opened. A downstream end of the nip where the rotary brush contacts the latent image carrier in the rotation direction of the rotary brush is not higher than a center of curvature of the latent image carrier where the rotary brush contacts, and the first tip of the brush housing is downstream of the rotary brush, further toward the latent image carrier than a tangent to the surface of the latent image carrier at the downstream end of the nip.
    Type: Grant
    Filed: July 23, 2008
    Date of Patent: September 14, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Tetsumaru Fujita, Yuji Nagatomo
  • Patent number: 7792463
    Abstract: A brush member includes plural raisings and contacts a surface of an image bearer downstream of a transfer station and temporary captures toner remaining on the surface of the image bearer into the brush member in a toner capturing process. The brush member returns the toner to the surface of the image bearer at a prescribed time in a toner returning process. A bending direction of the plural raisings is opposite in the returning process to that in the toner capturing process.
    Type: Grant
    Filed: March 18, 2008
    Date of Patent: September 7, 2010
    Assignee: Ricoh Company, Limited
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Patent number: 7751753
    Abstract: A cleanerless image forming apparatus configured to reduce the density unevenness of halftone images. The apparatus includes a photosensitive member, a charging roller device for uniformly charging the surface of the photosensitive member, an optical writing unit for forming latent images on the surface of the photosensitive member after uniform charging, a developing device for developing the latent toner image on the photosensitive member, a transfer unit for transferring the toner image to an intermediate transfer belt, and a brush member for trapping post-transfer residual toner adhering to the surface of the photosensitive member after passing through the transfer process by the transfer unit and before entering the developing process by the developing device, wherein the post-transfer residual toner is recovered within the developing device after re-transfer of the post-transfer residual toner within the brush member to the surface of the photosensitive member.
    Type: Grant
    Filed: December 12, 2007
    Date of Patent: July 6, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20100150609
    Abstract: A semiconductive member including an alkali metal salt having the formula (M)n·X in a surface layer thereof. M represents Na+, K+, or Li+; X represents Cl?, Br?, I?, F?, CH3COO?, CF3COO?, CH(COOH)CHCOO?, (CHCOO?)2, CH2(COOH)CH2COO?, (CH2COO?)2, (HOOC)Ar(COO?), Ar(COO?)2, (HOOC)2Ar(COO?), (HOOC)Ar(COO?)2, Ar(COO?)3, (HOOC)3Ar(COO?), (HOOC)2Ar(COO?)2, (HOOC)Ar (COO?)3, Ar(COO?)4, Ar—SO3?, Ar(SO3?)2, an oligomer or a polymer having an acrylic acid anion unit, or an oligomer or a polymer having an methacrylic acid anion unit; Ar represents a benzene ring, a naphthalene ring, or a biphenyl ring; and n is a numeral equivalent to the anionic valence of X.
    Type: Application
    Filed: November 20, 2009
    Publication date: June 17, 2010
    Inventors: Chiyoshi Nozaki, Tetsumaru Fujita, Shintaro Yamada, Yuji Nagatomo, Shin Murayama, Manabu Hamada, Yoshimichi Ishikawa
  • Patent number: 7738803
    Abstract: An image forming apparatus, performing a corresponding method of image forming, includes an image carrier, a writing unit, a developing unit, a charging member configured to rotate continuously with the image carrier at a portion contacting the image carrier and uniformly charge a surface of the image carrier while contacting a surface thereof with the surface of the image carrier, a charge bias applying unit configured to apply a charge bias to the charging member, and a controller configured to control of driving of the image carrier and the charging member and reduce at a charge nip at a given timing a linear velocity ratio of a travel speed of the surface of the charging member to a travel speed of the surface of the image carrier.
    Type: Grant
    Filed: September 4, 2007
    Date of Patent: June 15, 2010
    Assignee: Ricoh Company Limited
    Inventors: Tetsumaru Fujita, Yuji Nagatomo, Yoshio Sakagawa
  • Patent number: 7734227
    Abstract: A developing device 2a, which is provided with: a developer tank 16 that houses a developer 24 containing a toner, a carrier for charging the toner and reverse polarity particles that are charged with a polarity reversed to the electrostatic charge polarity of the toner by the carrier; a developer-supporting member 11 that supports the developer supplied from the developer tank on the surface thereof, and transports the developer; and a separating mechanism 22 that separates the toner or the reverse polarity particles from the developer supported on the developer-supporting member, and the reverse polarity particles are collected into the developer tank, is provided, and an image-forming apparatus having such a developing device and an image-forming method applied thereto are also provided.
    Type: Grant
    Filed: September 12, 2006
    Date of Patent: June 8, 2010
    Assignee: Konica Minolta Business Technologies, Inc.
    Inventors: Shigeo Uetake, Yuji Nagatomo, Junya Hirayama, Takeshi Maeyama, Masahiko Matsuura, Toshiya Natsuhara
  • Patent number: 7725054
    Abstract: An electrifying apparatus, a processing unit including the electrifying apparatus, and an image formation apparatus including the electrifying apparatus. The electrifying apparatus includes a conductive sheet for electrifying at least one of a surface of a photoconductor and toner adhered to the surface. The conductive sheet is specified to have a pure-water contact angle equal to or greater than 108 degrees, and to have a shore D hardness equal to or less than 65.
    Type: Grant
    Filed: December 12, 2007
    Date of Patent: May 25, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Tetsumaru Fujita, Yoshio Sakagawa, Yuji Nagatomo
  • Patent number: 7693459
    Abstract: A charging device and an image forming apparatus using the charging device. The charging device includes a charging member to uniformly charge a surface of a latent image bearing member in contact therewith, a charge bias application unit to apply a charge bias to the charging member, a conductive member to contact a surface of the charging member, and a different-valued bias application unit to apply a different-valued bias different from the charge bias to the conductive member. The image forming apparatus includes a latent image bearing member to bear a latent image, a latent image forming unit to form the latent image on the latent image bearing member, a development unit to develop the latent image with toner, and the charging device.
    Type: Grant
    Filed: September 14, 2007
    Date of Patent: April 6, 2010
    Assignee: Ricoh Company Limited
    Inventors: Tetsumaru Fujita, Yoshio Sakagawa, Yuji Nagatomo
  • Patent number: 7684732
    Abstract: An image forming apparatus includes at least a latent image carrier, a latent image forming mechanism, a developing mechanism and a charger. The latent image carrier bears a latent image. The latent image forming mechanism forms the latent image on the latent image carrier. The developing mechanism develops the latent image on the latent image carrier with toner. The charger includes a conductive member supplied with a bias voltage while contacting a surface of the latent image carrier, and charges at least one of the surface of the latent image carrier and a toner adhering to the surface thereof through the conductive member. A tensile strength of the conductive member at break is no less than 10 MPa and no more than 40 MPa, and a contact pressure between the conductive member and the latent image carrier is no less than 4 kN/m2 and no more than 15 kN/m2.
    Type: Grant
    Filed: December 14, 2007
    Date of Patent: March 23, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Tetsumaru Fujita, Yoshio Sakagawa, Yuji Nagatomo
  • Patent number: 7676184
    Abstract: A developing apparatus is disclosed that includes a developer carrier for carrying a developer used for developing a latent image, a developer supplying chamber having a developer supplying member for supplying the developer to the developer carrier by rotation, a developer storing chamber positioned above the developer supplying chamber for storing the developer and supplying the developer to the developer supplying chamber, and a partitioning member positioned between the developer supplying chamber and the developer storing chamber. The partitioning member has an opening through which the developer is supplied from the developer storing chamber to the developer supplying chamber. The developing apparatus includes a conveying member positioned above the partitioning member for conveying the developer in a substantially horizontal direction.
    Type: Grant
    Filed: November 30, 2007
    Date of Patent: March 9, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Shin Murayama, Shuuichi Nakagawa, Ryuji Inoue, Yuji Nagatomo, Shintaro Yamada, Kazushige Oonishi, Hirobumi Ooyoshi, Tomofumi Yoshida
  • Patent number: 7664433
    Abstract: An image forming apparatus includes a charging device for charging a photosensitive element having a moving surface, by bringing a charging roller, to which voltage is applied, into pressure-contact with the photosensitive element, wherein to the charging member there is applied voltage for forming an electric field such that toner adhered to the charging roller surface at a non-image forming area is oriented towards the photosensitive element. The image forming apparatus is provided with pressure contact force modifying means for making the pressure contact force of the charging roller against the photosensitive element at the non-image forming area greater than that at an image forming area.
    Type: Grant
    Filed: January 29, 2008
    Date of Patent: February 16, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Tetsumaru Fujita, Yoshio Sakagawa, Yuji Nagatomo
  • Patent number: 7539442
    Abstract: A charging unit available in a process unit detachably attached to an image forming apparatus includes a charging member configured to uniformly charge a surface of an image carrying member while contacting the image carrying member, and a charge bias applying unit configured to apply a charge bias superimposing a direct current voltage on an alternating current voltage to the charging member. The alternating current voltage satisfies a relational expression of “Vpp×0.4/t?8.8×103”, “Vpp” representing a peak-to-peak voltage of the alternating current voltage in the charge bias, and “t” representing a time period from a first point of a swing of a wave component starting to swing by a large amount to a same polarity as the direct current voltage of the charge bias to a second point of the swing of the wave component reaching approximately 80% of an amplitude of the wave component.
    Type: Grant
    Filed: June 6, 2007
    Date of Patent: May 26, 2009
    Assignee: Ricoh Company, Ltd.
    Inventors: Yuji Nagatomo, Tetsumaru Fujita
  • Publication number: 20090067887
    Abstract: An image forming apparatus includes a plurality of image carriers, a latent image forming unit, and a plurality of developing units. Each of the developing unit forms an image to have a color difference of equal to or less than about five with respect to an initial unicolor image formed by using a toner not containing a reversely-transferred toner of another color when a toner contained in a toner container is consumed by about 70%.
    Type: Application
    Filed: September 4, 2008
    Publication date: March 12, 2009
    Inventors: Tetsumaru Fujita, Yuji Nagatomo