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Reflection-type liquid crystal device with polarization of output light perpendicular to that of input light

  • US 5,361,151 A
  • Filed: 10/07/1993
  • Issued: 11/01/1994
  • Est. Priority Date: 08/09/1990
  • Status: Expired
First Claim
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1. A reflection-type liquid crystal device comprising:

  • a liquid crystal cell including a pair of spaced apart opposed transparent substrates,a polarizing means disposed at a first side said liquid crystal cell,a reflecting means disposed at a second side of said liquid crystal cell,said liquid crystal cell comprising a twisted nematic liquid crystal layer having a twist angle and having a birefringence property, Δ

    n, and having a thickness, d, for transforming the character of first linearly polarized light or first circularly polarized light propagating therethrough, respectively, into substantially circularly polarized light or substantially linearly polarized light incident at said reflecting means and transforming said substantially circularly polarized light or substantially linearly polarized light reflected from said reflecting means, respectively, into substantially second linearly polarized light or substantially second circularly polarized light having a polarization direction orthogonal with respect to a polarization direction of said first linearly polarized light or first circularly polarized light, respectively,said polarizing means characterized by having a polarization angle greater than zero wherein said polarization angle is an angle formed between a polarization axis of said polarizer and liquid crystal molecular director of said liquid crystal layer at a surface of said liquid crystal cell at said first side, andfirst and second optimized conditions for said twist angle relative to a given polarization angle and a product of Δ

    nd, the first optimized condition comprising a twist angle range between about 0° and

    65°

    with a Δ

    nd in a range between about 0.13 and 0.40, the second optimized condition comprising a twist angle range between about 0° and

    200°

    with Δ

    nd in a range between about 0.53 and 0.97,said optimized conditions applicable for said given polarization angle plus or minus multiplies of approximately 90°

    .

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