Patents by Inventor Kazuhiro Wakamatsu

Kazuhiro Wakamatsu 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: 6181889
    Abstract: An image forming apparatus in which a distance along a photosensitive belt from a cleaning unit to an exposing position is set to be shorter than a distance from the rear end of a print image to the front end of the following print image, so that a latent image is not formed by an exposing unit when a joint of the photosensitive belt passes the cleaning unit.
    Type: Grant
    Filed: February 24, 1997
    Date of Patent: January 30, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Tomio Hayano, Tetsuro Akasaki, Kazuhiro Wakamatsu, Isamu Terashima, Shoji Ukei
  • Patent number: 6081683
    Abstract: A color electrophotographic apparatus includes a photosensitive belt arranged obliquely, and a plurality of developing machines arranged on one side of the photosensitive belt in a stacked manner so as to be displaced from one another in a horizontal direction. The photosensitive belt is movable from below to above in a direction opposite to a direction of gravity when in a developing position. The developing machines include a non-magnetic, one component contact developing system having a developing roll for adhering toner on the photosensitive belt and a blade disposed below the developing roll for controlling an amount of toner adhering to the developing roll.
    Type: Grant
    Filed: May 3, 1996
    Date of Patent: June 27, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Toru Miyasaka, Toshiya Satoh, Hiroyuki Tadokoro, Kazuhiro Wakamatsu, Masahiko Saito
  • Patent number: 5621504
    Abstract: An apparatus for transferring toner images which is capable of executing optimum discharging control even where the environment, the material of the paper, and the kind of paper may be changed.First, the load current is detected when the transferring roller 11 is pressed to a transferring drum 6. The detected load current is converted to a characteristics detecting signal S6 at a signal converting section 109. An environment is selected on the basis of the characteristics detecting signal S6. Next, the load current flowing to the transferring roller 11 is detected when an AC discharger 14 is stopped. The detected load current is converted to characteristics detecting signal S6 at the signal converting section 109. A voltage control signal is selected based on the converted characteristics detecting signal S6, the environmental information, and the paper kind. A power source for discharging 22 is controlled by the selected voltage control signal so that the transferring becomes optimum.
    Type: Grant
    Filed: December 7, 1994
    Date of Patent: April 15, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Wakamatsu, Akira Sasaki, Nobuaki Fukasawa
  • Patent number: 5373354
    Abstract: A color electrophotographic device includes, a color toner image producing device which produces a color toner image on a rotatable photo sensitive drum by forming four toner images thereon; an image transferring device which transfers the color toner image on the photo sensitive drum onto a recording medium; a fixing means which fixes the color toner image on the recording medium; a transferring device which transfers the recording medium; a recording medium selecting and feeding device which selects one of an ordinary paper and a transparent sheet to serve as the recording medium and feeds the selected one to the transferring device; and a control device which controls the operations of the devices referred to above and includes a first and a second control function which are rendered operative when the transparent sheet is selected as the recording medium, wherein the first control function causes the photo sensitive drum to perform one idle rotation before the image transferring device beings to transfer
    Type: Grant
    Filed: August 26, 1992
    Date of Patent: December 13, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Tadokoro, Isamu Terashima, Kazuhiro Wakamatsu
  • Patent number: 5291254
    Abstract: In an electrophotographic recording apparatus, toner images of different colors formed on a photosensitive belt are transferred in overlapping fashion to an intermediate transfer drum to form a color toner image and the color toner image is transferred to a secondary recording medium by means of a transfer unit and then fixed. The intermediate transfer drum includes an electrically conductive drum substrate and a dielectric layer whose resistance is adjusted to a predetermined range, and the drum substrate is connected to earth potential so that setting of an electric field for toner image transfer from the photosensitive belt may not interfere with setting of an electric field for toner image transfer by the transfer unit. Efficiencies of transfer at the two transfer sections can be improved to provide a color image of high quality and the apparatus can be reduced in size.
    Type: Grant
    Filed: April 16, 1992
    Date of Patent: March 1, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Akira Shimada, Isamu Terashima, Tomoji Kitagishi, Kazuhiro Wakamatsu, Masahiko Saito
  • Patent number: 5113226
    Abstract: A roller forms a curve in a sheet of recording paper to which a toner image, formed on the curved surface of a photosensitive drum, is transferred such that a transfer curve extends along the curved surface of a transfer drum. The roller is provided in a path for carrying the recording paper so as to be in contact with the transfer drum.
    Type: Grant
    Filed: October 4, 1990
    Date of Patent: May 12, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Hiroyuki Tadokoro, Kazuhiro Wakamatsu, Syoji Sagae, Akira Shimada
  • Patent number: 4922272
    Abstract: A high precision image recording apparatus includes an electrophotographic device having at least a photosensitive drum and an exposure unit, for forming a toner image on the surface of the photosensitive drum; a recording sheet feed/transport unit for feeding and transporting a recording sheet to which the toner image formed on the surface of the photosensitive drum is transferred; a transfer unit for transferring the toner image on the photosensitive drum to the recording sheet fed and transported by the recording sheet feed/transport unit; and a drive unit for driving the photosensitive drum and recording sheet feed/transport unit. The drive unit is provided with a motor coupled to the photosensitive drum via a rotation transmission mechanism having a speed reduction ratio of 1/integer number (inclusive of 1/1), and the exposure unit is provided with a recording start position control unit for starting recording image information from a predetermined reference position on the photosensitive drum.
    Type: Grant
    Filed: July 31, 1989
    Date of Patent: May 1, 1990
    Assignees: Hitachi, Ltd., Hitachi Setsubi Engineering Co., Ltd.
    Inventors: Kazuhiro Wakamatsu, Seiji Yonekura, Mitsuo Suzuki, Hiroyuki Tadokoro, Atsuo Suzuki
  • Patent number: 4552449
    Abstract: An electrophotographic printer for producing a print of compound copied image and printed character image on a printing medium. The printer has a copying exposure system for forming the first electrostatic latent image on the printing medium on a drum by the exposure of the medium to an image in a certain area of a copy text through an electrically controlled optical switch, and a printing exposure system for forming the second electrostatic latent image by the exposure of the printing medium to a scanning laser beam which is modulated by a laser beam generator in accordance with literal information to be printed.
    Type: Grant
    Filed: October 21, 1983
    Date of Patent: November 12, 1985
    Assignee: Hitachi, Ltd.
    Inventors: Kazuhiro Wakamatsu, Yoshio Kawamata