Abstract: A light-emitting device having an organic EL element that has a light-emitting surface and emits light from the light-emitting surface, and a structure layer disposed directly or indirectly on the light-emitting surface. The structure layer has, on a surface thereof that is opposite to the organic electroluminescent element, a concavo-convex structure including a first streak array extending in a first direction that is parallel to the surface, a second streak array extending in a second direction that is parallel to the surface and intersects with the first direction, and a third streak array extending in a third direction that is parallel to the surface and intersects with the first direction and the second direction.

Abstract: A step of forming a layered body including a resin layer (a) containing a resin A having positive intrinsic birefringence and a resin layer (b) containing a resin B having negative intrinsic birefringence, the resin layer (b) being provided on one side of the resin layer (a); a first stretching step of stretching the layered body in one direction at a temperature T1; and a second stretching step of, after the first stretching step, stretching the layered body in another direction that is approximately orthogonal to the previous stretching direction at a temperature T2 which is lower than the temperature T1 to obtain a phase difference plate are performed.

Abstract: A surface light source device including an organic EL element of a double-side emission type and a light output surface structure layer provided on at least one surface of the organic EL 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 surface 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.

Abstract: An optical sheet comprising: a transparent substrate having a first surface S1 and a second surface S2; a first light diffusion layer provided on a first surface S1 side of the transparent substrate; and a second light diffusion layer provided on a second surface S2 side of the transparent substrate, wherein a haze x1 (%) of the first light diffusion layer and a haze x2 (%) of the second light diffusion layer satisfy f(x1)/(f(x1)+f(x2))? (where when x?88, a function f(x)=1.9×(1n(1?x/90))2, and when x>88, the function f(x)=22.5x?1952.5) and (f(x1)+f(x2))?12; and a surface light source device having the same.

Abstract: A phase difference plate is manufactured by a method including a step of forming a multilayer body by co-extruding or co-casting a resin A having a positive intrinsic birefringence value and a resin B having a negative intrinsic birefringence value, the multilayer body including a layer “a” containing the resin A and a layer “b” containing the resin B; a step of stretching the multilayer body at a temperature T1 in one direction; and a step of subsequently stretching the multilayer body at temperature T2 lower than the temperature T1 in a direction that is approximately orthogonal to the previous stretching direction. The resulting phase difference plate has specific in-plane retardation Rea of the layer “a”, retardation Rta in the thickness direction thereof, in-plane retardation Reb of the layer “b”, and retardation Rtb in the thickness direction thereof.

Abstract: A surface light source device includes an organic electroluminescent element including a luminescent layer and a light-emitting surface structure layer disposed on one of the surfaces of the organic electroluminescent element. In the surface light source device, the light-emitting surface structure layer includes a concave-convex structure provided on a surface thereof on the side toward a device light-emitting surface, and the concave-convex structure includes a plurality of concave portions having oblique surfaces and flat portions disposed around the concave portions. The flat portions and/or the concave portions have a size difference in one or more of their width, height, depth, and spacing, the size difference being larger than the difference that causes interference of one or both of emitted light and reflected light.