Patents by Inventor Keiko Kishimoto

Keiko Kishimoto 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: 6160595
    Abstract: An object of the invention is to obtain brighter display in a liquid crystal display apparatus. Light of all the wavelengths in the visible range is converted into circularly polarized light by a first polarization condition converting member, converted into linearly polarized light by a second polarization condition converting member and is modulated by a liquid crystal display device. Then, transmission and block of the light is controlled by a polarizer. Specifically, one of the dextrorotatory circularly polarized light and the levorotatory circularly polarized light is reflected by a spectral member included in the first polarization condition converting member, converted into the other circularly polarized light by a reflecting member included in the first polarization condition converting member and supplied again to the spectral member. The other circularly polarized light is transmitted by the spectral member.
    Type: Grant
    Filed: June 9, 1997
    Date of Patent: December 12, 2000
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Keiko Kishimoto
  • Patent number: 5699137
    Abstract: It is an object of the invention to provide a liquid crystal display device capable of obtaining a wide viewing angle without coloration caused by a viewing angle. A liquid crystal display cell is disposed between a pair of polarizers, and between the liquid crystal display cell and the pair of polarizers, first optical compensation plates are disposed at the side of the liquid crystal display cell, and second optical compensation plates are disposed at the side of the polarizer. The first optical compensation plates have a refractive index anisotropy in the plane, and the refractive index thereof in the thickness direction is nearly equal to the refractive index of a minimum value in the plane, whereas the second optical compensation plates have no refractive index anisotropy in the plane, the refractive index in the thickness direction is greater than the refractive index in the plane, and a positive phase difference is expressed by inclination from the normal direction.
    Type: Grant
    Filed: August 15, 1996
    Date of Patent: December 16, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Keiko Kishimoto
  • Patent number: 5493431
    Abstract: A liquid crystal display device of stable color tone uses phase difference plates made of a uniaxially stretched polymer film and comprises a polarizer plate, a first phase difference plate, a second phase difference plate, a supertwisted nematic type liquid crystal display panel, and a polarizer plate which are stacked on each other in this order. The rate of retardation change with the change in viewing angle of the uniaxially stretched polymer film is denoted coefficient K defined by three-dimensional refractive indexes, coefficient K1 of one of the phase difference plates is set in a range of -1.ltoreq.K1.ltoreq.0.17 and coefficient K2 of the other phase difference plate is set in a range of 0.ltoreq.K2.ltoreq.1.
    Type: Grant
    Filed: January 28, 1993
    Date of Patent: February 20, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yumi Baba, Hiroshi Ohnishi, Toshiyuki Yoshimizu, Keiko Kishimoto
  • Patent number: 5400158
    Abstract: A liquid crystal display is disclosed. The liquid crystal display includes: a liquid crystal panel including a pair of substrates and super twisted nematic liquid crystal having a twisted structure with a twist angle of 180.degree. or more, the super twisted nematic liquid crystal being contained between the pair of substrates; a pair of polarizing plates which sandwich the liquid crystal panel; an optically anisotropic plate having a twisted structure with a twist angle of 90.degree. or less, the optically anisotropic plate being disposed between one of the pair of polarizing plates and the liquid crystal panel, or between the other one of the pair of polarizing plates and the liquid crystal panel; and a phase plate of a polymeric film which is uniaxially extended, the phase plate being disposed between one of the pair of polarizing plates and the liquid crystal panel, or between the other one of the pair of polarizing plates and the liquid crystal panel.
    Type: Grant
    Filed: July 23, 1993
    Date of Patent: March 21, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroshi Ohnishi, Keiko Kishimoto
  • Patent number: 5291323
    Abstract: In a liquid crystal display device using uniaxially drawn polymer film as a phase difference plate, as the elevation angle becomes wider, the difference between the retardation of the phase difference plate and the retardation of the liquid crystal display panel becomes larger, and the optical compensation relation is broken, and the viewing angle becomes narrower. To solve this problem, uniaxially drawn polymer films are prepared separately from polycarbonate and polystyrene which differ in the optical properties, and they are disposed as the optical compensation plate at the front side and back side of a liquid crystal cell, or they are laminated and disposed at the front side and back side of a liquid crystal cell.
    Type: Grant
    Filed: September 30, 1991
    Date of Patent: March 1, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroshi Ohnishi, Toshiyuki Yoshimizu, Yumi Yoshimura, Keiko Kishimoto
  • Patent number: 5249071
    Abstract: In a supertwist type liquid crystal display, a pair of upper and lower polarizers and polymer films are disposed in such an arrangement that the upper polarizer, first uniaxial oriented polymer film, second uniaxial oriented polymer film, supertwist type liquid crystal cell, third uniaxial oriented polymer film, first biaxial oriented polymer film and the lower polarizer are sequentially piled on in this order, and each of said first, second and third uniaxial oriented polymer films has a positive optical anisotropy and said first biaxial oriented polymer film has a negative optical anisotropy.
    Type: Grant
    Filed: November 20, 1991
    Date of Patent: September 28, 1993
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Toshiyuki Yoshimizu, Hiroshi Ohnishi, Yumi Yoshimura, Keiko Kishimoto
  • Patent number: 5235450
    Abstract: A liquid crystal display apparatus includes a twist supertwisted nematic liquid crystal panel (1) including a liquid crystal layer (8) provided between first and second transparent substrates (2, 3), and a first phase plate group (11; 13, 14) including at least one uniaxially stretched polymer film arranged on the outer surface of the first substrate (2). The apparatus further includes a first polarizing plate (9) arranged on the first phase plate group (11; 13, 14) and a second phase plate group (12; 15, 16) including at least one uniaxially stretched polymer film arranged on the outer surface of the second substrate (3) and. Finally, the apparatus includes a second polarizing plate (10) arranged on the second phase plate group (12; 15, 16), wherein at least one of the uniaxially stretched polymer films (11, 12; 13, 14, 15, 16) has positive optical anisotropy and the others have negative optical anisotropy.
    Type: Grant
    Filed: September 27, 1991
    Date of Patent: August 10, 1993
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yumi Yoshimura, Hiroshi Ohnishi, Toshiyuki Yoshimizu, Keiko Kishimoto