SURFACE LIGHT SOURCE DEVICE

摘要

Disclosed is a surface light source device that can realize high light-takeout efficiency and causes no significant change in color depending upon a viewing angle. The surface light source device comprises a layer having a concave and convex structure formed of a resin composition that is provided on a light outgoing surface of the surface light source device. The surface light source device is characterized in that the layer having a concave and convex structure is in a conical, pyramid or prism form and the resin composition contains a transparent resin and particles. In particular, in the surface light source device, the displacement of an x coordinate or a y coordinate in hemispherical omnidirectional chromaticity coordinates in the light outgoing surface is within ±0.1, the diameter of the particles is not more than 10 µm, the content of the particles is 1 to 40% by weight of the total amount of the resin composition, and the difference in refractive index between the particles and the transparent resin is 0.05 to 0.5.