Patents by Inventor Takashi Hayakawa

Takashi Hayakawa 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: 5708929
    Abstract: In an image forming apparatus, when a transferred material exists in a transfer position between a photoreceptor drum and a transfer unit during an image forming operation, a transfer voltage, which has opposite polarity to that of a voltage applied to a brush charger and is used for transferring a developer image on the photoreceptor drum onto the transferred material is applied to the transfer unit. Meanwhile, when a transferred material does not exist in the transfer position during the image forming operation, a non-transfer voltage, which is lower than the transfer voltage, is applied to the transfer unit. As a result, defects on an image due to returning of a developer from the brush charger to the photoreceptor drum can be prevented from being generated.
    Type: Grant
    Filed: March 13, 1996
    Date of Patent: January 13, 1998
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Katsumi Adachi, Takashi Hayakawa
  • Patent number: 5689778
    Abstract: An image forming apparatus adopting a cleaningless process using contact-type charging means, includes developer scattering means which is located between the charging means and an exposure position in contact with the surface of an image carrier. For example, the developer scattering means is a conducting brush which scatters, catches and temporarily holds the residual toner on the image carrier. With this structure, even in an image forming apparatus adopting the cleaningless process using the contact-type charging means, the residual toner on the image carrier is scattered and caught by developer catching means before the residual toner reaches the exposure position. Thus, a lowering of the image quality which is caused if the residual toner is patterned by the charging means is prevented, thereby improving the image quality.
    Type: Grant
    Filed: November 13, 1995
    Date of Patent: November 18, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Katsumi Adachi
  • Patent number: 5602659
    Abstract: A photoconductor coupled liquid crystal light valve comprising at least a pair of transparent electrode, a liquid crystal layer and a photoconductive layer showing blocking properties both sandwiched between said transparent electrodes, wherein said photoconductive layer includes a light absorbing layer and a blocking layer having a band gap wider than said light absorbing layer, both said light absorbing layer and said blocking layer being formed of non-alloy a-Si; and a method for manufacturing said photoconductor coupled light valve wherein said photoconductive layer is prepared with electron cyclotron resonance method.
    Type: Grant
    Filed: February 2, 1995
    Date of Patent: February 11, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Katsumi Adachi, Takashi Hayakawa, Shiro Narikawa
  • Patent number: 5592263
    Abstract: A charging device for use in an image forming apparatus is disclosed which charges an object to be charged by contacting a conductive charging member with the surface of the object and then applying a voltage across the charging member and the object,wherein at least a contact portion of the charging member comprises a conductive material having a hygroscopic degree of 0.2% or less.
    Type: Grant
    Filed: June 13, 1994
    Date of Patent: January 7, 1997
    Assignees: Gunze Limited, Sharp Kabushi Kaisha
    Inventors: Katsumi Adachi, Shiro Narikawa, Takashi Hayakawa, Yukihito Nishio, Hirofumi Yanagizawa, Takumi Sakamoto, Atsushi Okada
  • Patent number: 5563691
    Abstract: An image-forming apparatus including a cleaning means for selectively removing foreign matters other than developer remaining on the surface of a photoconductor drum therefrom after a transferring process. The cleaning means is provided with a foreign-matter removing roller which comes into contact with the surface of the photoconductor drum. Foreign matters, which are charged by a transferring device to have a polarity reversed to that of the charged electric potential of toner through an electric field that is exerted between the surfaces of the roller and the photoconductor drum, are allowed to adhere to the surface of the foreign-matter removing roller. As for the surface of the foreign-matter removing roller, the surface electric potential of the foreign-matter removing roller is biased farther toward the polarity of the charged toner than the surface electric potential of the photoconductor drum at the contact portion between the photoconductor drum and the foreign-matter removing roller.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: October 8, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Katsumi Adachi, Yuhi Yui
  • Patent number: 5555079
    Abstract: In an image forming apparatus including a charging element, a charged element, a developing element, and a cleaning element the dimensions of those elements satisfy either or both of the following relations:C+D<A<B-DC<E<A+Dwhere A denotes a longitudinal dimension of the charging element; B denotes an effective longitudinal width of a photoconductive layer coated range on the charged element; C denotes a developing width in the longitudinal direction of a developing element; D denotes a vibrating width of the charging member; and E denotes a longitudinal dimension of a cleaning element for the charged element.
    Type: Grant
    Filed: November 16, 1994
    Date of Patent: September 10, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Katsumi Adachi, Takashi Hayakawa
  • Patent number: 5426488
    Abstract: A charging member comprised of a conductive shaft and conductive fibers planted thereon is brought into contact with a charged member with a photoconductor provided on the surface thereof. The conductive shaft is applied with a combined voltage of d.c. voltage and a.c. voltage having a peak-peak value lower than two times the discharge starting threshold voltage that is determined by the surrounding atmosphere around the charged member. While the charging member and the charged member rotate at different surface velocity, the charged member is charged through the contact area in which impedance is low due to the influence of a.c. voltage, so that a stable surface potential close to the d.c. voltage may be charged onto the charged member. Further, it is effective that the frequency f of the a.c. voltage will be so set up as to suffice a relation: f>Vp/2R, where f is a frequency of the applied a.c. voltage, Vp(mm/s) is a moving velocity of the charged member, and R(mm) is a particle size of a developer used.
    Type: Grant
    Filed: October 14, 1993
    Date of Patent: June 20, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Kenji Tani, Katsumi Adachi
  • Patent number: 5398102
    Abstract: The invention is directed to an apparatus for an electrophotographic process, equipped with a charging device of a contact type using a conductive roller or brush, and the charging device used therefor.
    Type: Grant
    Filed: April 21, 1993
    Date of Patent: March 14, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takasumi Wada, Kenji Tani, Takashi Hayakawa, Kouichi Irihara, Yukihito Nishio
  • Patent number: 5338582
    Abstract: A photoconductor coupled liquid crystal light valve which comprises a pair of substrates opposite to each other, transparent electrodes arranged on each of the substrates, either one having a photoconductive layer and a carrier trapping layer formed over the transparent electrodes, a liquid crystal layer injected between the substrates and a voltage application means between the transparent electrodes.
    Type: Grant
    Filed: September 8, 1993
    Date of Patent: August 16, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Takashi Hayakawa
  • Patent number: 5324549
    Abstract: A method for fabricating a photoconductor coupled liquid crystal valve comprising the step of; deposing a transparent electrode on a transparent substrate; forming on said transparent electrode a photoconductive layer formed of amorphous silicon by the ECR; forming on said photoconductive layer an optical shielding layer formed of amorphous silicon by the ECR; forming on said optical shielding layer an optical reflection layer; forming an orientation film on said optical reflection layer; laminating on said orientation film a transparent substrate having a transparent electrode and another orientation film stoked thereon by the above method in such a manner that the two orientation films face each other with a spacer interposed therebetween; and disposing liquid crystals into said spacer.
    Type: Grant
    Filed: December 18, 1992
    Date of Patent: June 28, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Shiro Narikawa, Katsumi Adachi, Akitsugu Hatano
  • Patent number: 5245059
    Abstract: 2,3,5-Trimethyl-p-benzoquinone is prepared advantageously by the catalytic oxidation of 2,3,5- or 2,3,6-trimethylphenol with hydrogen peroxide in an organic solvent, which is preferably acetic acid, in the presence of a catalyst which is a heteropolyacid of silicon or phosphorus as the center atom selected from phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid and silicotungstic acid. The reaction proceeds rapidly even at room temperature to give the product in a high yield so that the method is industrially advantageous in addition to the advantages in respect of the inexpensiveness of the reactants and catalyst and absence of any noxious byproducts which may cause environmental pollution.
    Type: Grant
    Filed: March 3, 1989
    Date of Patent: September 14, 1993
    Assignee: Japan as represented by Director General of Agency of Industrial Science and Technology
    Inventors: Masao Shimizu, Katsuomi Takehira, Takashi Hayakawa, Hideo Orita
  • Patent number: 5239397
    Abstract: A photoconductor coupled liquid crystal light valve comprising a photoconductor layer, a liquid crystal layer and electrodes for applying voltage to the layers. The photoconductive layer is made of amorphous silicon containing hydrogen and/or halogen at more than 40 at%. The photoconductive layer preferably has a resistivity of between 10.sup.11 and 10.sup.12 ohm-cm and a photonconductivity of 10.sup.-8 and 10.sup.-6 cm.sup.2 /V. The photoconductive layer is preferably formed by electron cyclotron resonance.
    Type: Grant
    Filed: February 19, 1992
    Date of Patent: August 24, 1993
    Assignee: Sharp Kabushiki
    Inventors: Takashi Hayakawa, Shiro Narikawa, Kunio Ohashi
  • Patent number: 5164281
    Abstract: A photosensitive body for electrophotography has as its principal constituent a photoconductive layer having amorphous silicon with hydrogen, a surface layer having a greater optical band gap than the photoconductive layer formed on a photoconductive base member, and an intermediate layer sandwiched therebetween.
    Type: Grant
    Filed: November 29, 1989
    Date of Patent: November 17, 1992
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Shoichi Nagata, Shiro Narukawa, Kazuki Wakita, Kunio Ohashi, Yoshikazu Fujiwara
  • Patent number: 5126499
    Abstract: A process for the production of hydrocarbons having 2 or more carbon atoms by oxidative coupling of methane includes a step of contacting a feed gas containing methane with an oxide of metals having the following composition:MCo.sub.1-x Fe.sub.x O.sub.ywherein M stands for at least one alkaline earth metal x is a number greater than 0 but not greater than 1 and y is a number in the range of 2.5-3.5, at a temperature of 500.degree.-1000.degree. C.
    Type: Grant
    Filed: March 20, 1991
    Date of Patent: June 30, 1992
    Assignee: Director-General of Agency of Industrial Science and Technology
    Inventors: Takashi Hayakawa, Katsuomi Takehira, Hideo Orita, Masao Shimizu, Yoshihito Watanabe
  • Patent number: 5100749
    Abstract: An improved photosensitive member for electrophotography which comprises an intermediate layer, a photoconductive layer and a surface protecting layer each formed upwardly in this order on a conductive substrate, the photoconductive layer comprising a non-doped a-Si layer made of a amorphous silicon containing hydrogen and/or halogen of 40 at. % or more.
    Type: Grant
    Filed: February 19, 1991
    Date of Patent: March 31, 1992
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Shiro Narikawa, Takashi Hayakawa, Kunio Ohashi
  • Patent number: 5085968
    Abstract: A photosensitive member for electrophotography which comprises a conductive substrate and a photoconductive layer which is composed of an amorphous silicon layer and an amorphous silicon germanium layer containing a specific amount of hydrogen and/or halogen respectively, and being prepared by electron cyclotron resonance method respectively, which is useful for xerographic systems.
    Type: Grant
    Filed: December 3, 1990
    Date of Patent: February 4, 1992
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Shiro Narikawa, Kunio Ohashi
  • Patent number: 5057391
    Abstract: A photosensitive member for electrophotography comprising a photoconductive layer formed on an electro- conductive support, in which the photoconductive layer is composed of an amorphous silicon germanium layer formed by electron cyclotron resonance (ECR) method and containing hydrogen and/or halogen in an amount of more than 40 at. % to 65 at. % and an amorphous silicon nitride layer formed by ECR method and containing hydrogen and/or halogen in an amount of more than 40 at. % to 60 at. %, the amorphous silicon nitride layer being laminated on the amorphous silicon germanium layer; said member exhibiting an increased sensitivity to laser rays having a long wavelength and an improved charge retention capacity.
    Type: Grant
    Filed: May 15, 1990
    Date of Patent: October 15, 1991
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Shiro Narikawa, Kunio Ohashi, Yoshiharu Tsujimoto
  • Patent number: 5009977
    Abstract: A photosensitive member for electrophotographic photoreceptor, composed of an amorphous silicon containing carbon; nitrogen or oxygen and a specific amount of hydrogen and/or halogen, prepared by electron cyclotron resonance method, which is useful for xerographic systems.
    Type: Grant
    Filed: June 21, 1989
    Date of Patent: April 23, 1991
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takashi Hayakawa, Shiro Narikawa, Kunio Ohashi, Yoshiharu Tsujimoto
  • Patent number: 4994855
    Abstract: A photoreceptor for an image formation apparatus has a photosensitive layer of a multi-layer structure each having the characteristic of increasing its electrical resistance at a different rate upon expose to light. An image-carrying beam of reflected light from an original to be copied is made incident on the photoreceptor to form a resistance image. An electrostatic latent image is formed therefrom either on the photoreceptor itself or on a transfer medium placed in contact therewith and a visible toner image is formed by applying toner on such an electrostatic image but the resistance image on the photoreceptor remains undisturbed during such image transfer processes. Thus, a plurality of copies of a single original can be produced without exposing the photoreceptor to reflected light therefrom for each copy to be printed.
    Type: Grant
    Filed: May 26, 1988
    Date of Patent: February 19, 1991
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Kunio Ohashi, Yoshikazy Fujiwara, Shiro Narikawa, Shoichi Nagata, Kazuki Wakita, Takashi Hayakawa
  • Patent number: D334337
    Type: Grant
    Filed: August 13, 1990
    Date of Patent: March 30, 1993
    Assignee: Sumitomo Wiring Systems, Ltd.
    Inventors: Takayoshi Ito, Takashi Hayakawa