Patent ID: 7630026

Claim:
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, and wherein 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.