Normally white LCD including first and second biaxial retarders

  • US 6,229,588 B1
  • Filed: 03/26/1998
  • Issued: 05/08/2001
  • Est. Priority Date: 12/15/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A normally white liquid crystal display capable of displaying an image to a viewer, the display comprising:

  • a pair of electrodes sandwiching a twisted nematic liquid crystal layer therebetween, said pair of electrodes for applying a voltage across said liquid crystal layer;

    first and second orientation layers disposed adjacent said liquid crystal layer on opposite sides thereof, said first and second orientation layers for aligning liquid crystal molecules of said liquid crystal layer in a predetermined manner;

    first and second biaxial retardation members provided in the display;

    said liquid crystal layer being provided so as to twist at least one wavelength of light passing therethrough from about 80°

    -100°

    ;

    each of said first and second biaxial retardation members at at least one location therein being defined by nx>

    ny>

    nz, wherein nx, ny, and nz are indices of refraction with the “

    z”

    direction being perpendicular to the “

    x” and



    y”

    directions; and

    wherein for each of said first and second biaxial retardation members d·

    Δ

    nzx is from about −

    100 to −

    200 nm, and wherein said first and second biaxial retardation members are oriented with respect to each other so that the display can achieve a white light contrast ratio of at least about 30;

    1 over a horizontal viewing angular span of at least about 80° and

    over a vertical viewing angular span of greater than about 30°

    .

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