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: 20090028606
    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: Application
    Filed: July 23, 2008
    Publication date: January 29, 2009
    Inventors: Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080273898
    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: Application
    Filed: December 12, 2007
    Publication date: November 6, 2008
    Inventors: Yoshio Sakagawa, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080232875
    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: Application
    Filed: March 18, 2008
    Publication date: September 25, 2008
    Inventors: Yoshio SAKAGAWA, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080227001
    Abstract: An image forming method, including recharging untransferred toner remaining on a latent electrostatic image bearing member by using a recharging member to remove the untransferred toner from the latent electrostatic image bearing member, wherein the recharging member is a conductive member a surface of which has a contact angle of 108° or more with pure water and a Shore D hardness of 50 to 65; the coverage of the surface of the toner by an external additive is 150% or less; and a releasing agent peak ratio obtained by ATR method is 0.02 to 0.1.
    Type: Application
    Filed: March 14, 2008
    Publication date: September 18, 2008
    Inventors: Takuya KADOTA, Chiyoshi Nozaki, Tsuyoshi Nozaki, Hiroyuki Murakami, Mitsuyo Matsumoto, Atsushi Yamamoto, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080187361
    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: Application
    Filed: January 31, 2008
    Publication date: August 7, 2008
    Inventors: Yoshio SAKAGAWA, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080187360
    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: Application
    Filed: January 29, 2008
    Publication date: August 7, 2008
    Inventors: Tetsumaru FUJITA, Yoshio Sakagawa, Yuji Nagatomo
  • Publication number: 20080181655
    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: Application
    Filed: January 25, 2008
    Publication date: July 31, 2008
    Inventors: Yoshio SAKAGAWA, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080181654
    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: Application
    Filed: January 10, 2008
    Publication date: July 31, 2008
    Inventors: Yoshio SAKAGAWA, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080152385
    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: Application
    Filed: December 14, 2007
    Publication date: June 26, 2008
    Inventors: Tetsumaru FUJITA, Yoshio Sakagawa, Yuji Nagatomo
  • Publication number: 20080152384
    Abstract: An electrifying apparatus, a processing unit including the electrifying apparatus, and an image formation apparatus including the electrifying apparatus are disclosed. 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: Application
    Filed: December 12, 2007
    Publication date: June 26, 2008
    Inventors: Tetsumaru FUJITA, Yoshio SAKAGAWA, Yuji NAGATOMO
  • Publication number: 20080145100
    Abstract: A cleanerless image forming apparatus capable of reducing the density unevenness of halftone images, comprising a photosensitive member; charging roller means for uniformly charging the surface of the photosensitive member; an optical writing unit which is not shown on the drawings, for forming latent images on the surface of the photosensitive member after uniform charging thereof; a developing device for developing the latent image on the photosensitive member to obtain a toner image; a transfer unit for transferring the toner image on the surface of the photosensitive member 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 memb
    Type: Application
    Filed: December 12, 2007
    Publication date: June 19, 2008
    Inventors: Yoshio SAKAGAWA, Tetsumaru Fujita, Yuji Nagatomo
  • Publication number: 20080145109
    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: Application
    Filed: November 30, 2007
    Publication date: June 19, 2008
    Inventors: Shin MURAYAMA, Shuuichi Nakagawa, Ryuji Inoue, Yuji Nagatomo, Shintaro Yamada, Kazushige Oonishi, Hirobumi Ooyoshi, Tomofumi Yoshida
  • Publication number: 20080069592
    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: Application
    Filed: September 14, 2007
    Publication date: March 20, 2008
    Inventors: Tetsumaru Fujita, Yoshio Sakagawa, Yuji Nagatomo
  • Publication number: 20080056745
    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: Application
    Filed: September 4, 2007
    Publication date: March 6, 2008
    Inventors: Tetsumaru Fujita, Yuji Nagatomo, Yoshio Sakagawa
  • Publication number: 20080038017
    Abstract: An image forming apparatus, performing a corresponding method of image forming, includes an image carrier, a charging unit including a first charging member for discharging a given amount of bias to a portion contacting the image carrier and uniformly charging the surface of the image carrier while contacting the surface of the image carrier, a charge bias applying unit for applying a charge bias including at least an alternating current voltage to the first charging member, a writing unit, and a developing unit. In the image forming apparatus, a ratio of a frequency of the alternating current voltage to a surface linear velocity of the image carrier is within a range of from approximately 1.5:1 to approximately 4:1 and a ratio of a surface linear velocity of the first charging member to the surface linear velocity of the image carrier is at least 2:1.
    Type: Application
    Filed: August 10, 2007
    Publication date: February 14, 2008
    Inventors: Tetsumaru FUJITA, Yuji Nagatomo
  • Publication number: 20070280735
    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: Application
    Filed: June 6, 2007
    Publication date: December 6, 2007
    Inventors: Yuji Nagatomo, Tetsumaru Fujita
  • Patent number: 7233755
    Abstract: An image forming apparatus which reduces abrasion of a photosensitive drum caused by a rotary brush such as an charging brush for electrically charging the surface of a photosensitive drum or a cleaning brush for cleaning the surface of a photosensitive drum. The rotary brush is in contact with the photosensitive drum. During the period of charging the photosensitive drum or cleaning its surface, the rotary brush is rotated in a first mode in which the brush rotates rubbing and sliding the surface of the photosensitive drum, and during other periods, in a second mode in which the brush is rotated passively as driven by rotation of the photosensitive drum. Abrasion of the photosensitive drum is reduced by properly controlling the width of contact between the rotary brush and photosensitive drum and the amount of push for pressing the brush against the photosensitive drum.
    Type: Grant
    Filed: March 31, 2004
    Date of Patent: June 19, 2007
    Assignee: Konica Minolta Business Technologies, Inc.
    Inventors: Makiko Tango, Yuji Nagatomo
  • Patent number: 7202675
    Abstract: A toner current measuring device able to measure a toner current. The toner current measuring device having provided therein a toner deposit capacitor c1 including an electrode 11 and an electrode 12 disposed in opposition, a reference capacitor c2 having a mechanism for adjusting a capacitance thereof; a power supply unit 4; and a measuring unit 10 for measuring, when a voltage is applied to both capacitors to cause a transfer, between the opposing electrodes, of charged toner deposited on the electrode 11, a difference between currents flowing in the toner deposit capacitor c1 and the reference capacitor c2, the difference being measured as a toner current generated as a result of the transfer of the charged toner.
    Type: Grant
    Filed: October 18, 2005
    Date of Patent: April 10, 2007
    Assignee: Konica Minolta Holdings, Inc.
    Inventors: Shigeo Uetake, Junya Hirayama, Masahiko Matsuura, Takeshi Maeyama, Yuji Nagatomo
  • Publication number: 20070071506
    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: Application
    Filed: September 12, 2006
    Publication date: March 29, 2007
    Inventors: Shigeo Uetake, Yuji Nagatomo, Junya Hirayama, Takeshi Maeyama, Masahiko Matsuura, Toshiya Natsuhara
  • Patent number: 7082277
    Abstract: A contact charger for charging a charging target (e.g., a photosensitive member) includes a charging brush to be in contact with the charging target, and auxiliary charging particles to be interposed between the brush and the charging target. The auxiliary charging particle takes an acicular form having an aspect ratio from 2 to 10000, and satisfies a relationship of (L2/T?200) between a length L (?m) of a long axis of the particle and a thickness of T (deniers) of a brush fiber of the brush.
    Type: Grant
    Filed: March 4, 2004
    Date of Patent: July 25, 2006
    Assignee: Konica Minolta Business Technologies, Inc.
    Inventors: Yuji Nagatomo, Makiko Tango