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Planar light source, display device, portable terminal device, and ray direction switching element

  • US 7,630,026 B2
  • Filed: 01/28/2008
  • Issued: 12/08/2009
  • Est. Priority Date: 05/24/2004
  • Status: Active Grant
First Claim
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1. A planar light source comprising:

  • a backlight that emits light in a planar shape;

    a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light, whereby a directivity of the light is improved, said ray direction regulating element comprising a transparent area for transmitting light and an absorption area for absorbing light are formed alternately in a direction parallel to a surface of the ray direction regulating element; and

    a transparent and scattering switching element that is switchable between a state in which light which is transmitted by the ray direction regulating element and made incident on said switching element is transmitted and a state in which the light is scattered;

    wherein light emitted by the backlight spreads radially in an elliptical shape with respect to a direction perpendicular to an emission surface of said backlight, andwherein the transparent area and the absorption area of the ray direction regulating element are formed alternately in a direction parallel to a short diameter direction of the elliptical shape.

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