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Backlighting apparatus for uniformly illuminating a display panel

  • US 5,440,197 A
  • Filed: 10/05/1993
  • Issued: 08/08/1995
  • Est. Priority Date: 10/05/1993
  • Status: Expired due to Term
First Claim
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1. An apparatus, comprising:

  • a display panel having a rear surface and a front surface, said display panel being at least partially transmissive such that at least a portion of illumination on said rear surface is transmitted to said front surface;

    a light source for backlighting said display panel, said light source comprising;

    a light bulb;

    a housing having diffusive reflective interior surfaces forming a fluid-containing cavity, said cavity having a depth, said bulb mounted in said cavity with said interior surfaces of said cavity spaced therefrom, said housing having an aperture which opens into said cavity, said aperture juxtaposed with said rear surface of said display panel to illuminate said rear surface, said cavity having a diffusive reflective surface area and said aperture having an area, the ratio of said area of said aperture to the sum of (i) said area of said aperture and (ii) said surface area of said cavity being at least 0.05, said aperture having a bisector dimension, the ratio of said depth to said bisector dimension being at least 0.1;

    a diffuser at said aperture, said diffuser positioned to diffuse illumination which passes through said aperture from said cavity toward said display panel;

    a brightness enhancing material disposed between said diffuser and said display panel, said material providing illumination within a maximal viewing angle and reflecting illumination outside said maximal viewing angle.

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