| 摘要 |
A surface light source device comprises a light emitting section ( 11 ) made of a single spot light source, a light guide plate ( 12 ), a reflective surface ( 13 ) provided on the back side of the light guide plate, and a prism pattern ( 15 ). On the light emitting surface side of the light guide plate ( 12 ), there is provided a directional light scattering film ( 14 ) consisting of at least two phases having different refractive indexes and scattering light when transmitting it. One phase of a larger refractive index includes a plenty of areas having a columnar structure extending in the thickness direction of a film and arranged to be perpendicular to a normal to the film, and exhibiting a maximum scattering angle of 10-40°.
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