Patent ID: 9018836
Filing Date: 2015-04-28
Classification: H01L

Abstract:
1. A surface light source device comprising: an organic electroluminescent element of a double-side emission type having a first transparent electrode layer, a light-emitting layer, and a second transparent electrode layer provided in this order; and a light output surface structure layer provided directly or indirectly on at least one surface of the organic electroluminescent element, wherein the light output surface structure layer includes a concavo-convex structure on a surface opposite to the organic electroluminescent element, the concavo-convex structure having flat surface portions parallel to the at least one surface of the organic electroluminescent element and an inclined surface portion tilted relative to the flat surface portions, and a projected area, formed by projecting the inclined surface portion in a direction perpendicular to the flat surface portions onto a plane parallel to the flat surface portions, is not more than 0.1 times a total area of the flat surface portions.