El panel, and illumination device and display device using the same

An EL panel comprising:

• a light-transmissive substrate;
• an EL element comprising a light-emitting medium layer interposed between a cathode and an anode, the EL element being provided on one surface of the light-transmissive substrate;
• and
• a protection sheet having a first surface provided on the other surface of the light-transmissive substrate of the EL element and a second surface opposite to the first surface, wherein
• a plurality of rounded convex portions are provided on the second surface of the protection sheet to form of a logo, a mark, a pattern according to the density of the convex portions,
• a plurality of prism portions are periodically provided on the second surface of the protection sheet to extend to one direction or two direction,
• each of the convex portions has an apex that is a center point of a cross-section farthest from a bottom surface where the cross-section is parallel to the bottom surface of the convex portion and the area becomes smaller in a direction from the bottom surface to a top portion thereof, and
• where the height of the apex is represented as Tc, the distance between the apexes of adjacent convex portions is represented as Bc, and the height of the prism portion is represented as Tp, the following formula is satisfied
• 2(Tc−Tp)≦Bc≦10(Tc−Tp).