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Front illumination device and reflection-type liquid crystal display device incorporating same

  • US 6,048,071 A
  • Filed: 03/23/1998
  • Issued: 04/11/2000
  • Est. Priority Date: 03/28/1997
  • Status: Expired due to Term
First Claim
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1. A front illumination device, comprising:

  • a light source;

    a first light-conducting body which guides light from said light source to an object to be illuminated, which is to be used by mounting in front of said object to be illuminated;

    wherein said first light-conducting body is a polyhedron provided with a light-entry surface through which light from said light source enters, a first light exit surface through which light exits toward said object to be illuminated, and a second light exit surface opposite said first exit surface;

    wherein said first and second light exit surfaces are provided so as to be substantially parallel;

    wherein said light-entry surface is provided so as to incline with respect to a normal direction of said first light exit surface;

    a light control means, provided between said light source and said light-entry surface, which limit spread of light from said light source; and

    wherein the following inequality is satisfied,
    
    
    space="preserve" listing-type="equation">arcsin((sin δ

    )/n.sub.1)<

    β

    where β

    is an angle formed by said light-entry surface and a normal direction of said first light exit surface, n1 is a refractive index of said first light-conducting body, and ±

    δ

    is an angle of spread of light limited by said light-control means.

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