Light-emitting device with light flux control member having prismatic elements on bottom surface forming acute angle with side edge of light source

Abstract

A light-emitting element includes a rectangular light emitting element with four edge surfaces; and a light flux control member defining a central axis and having a back surface, light entry surface formed as a recess in the back surface, a light emission surface disposed opposite the back surface, and a plurality of protruding elements forming a grid on the back surface. The grid of protruding elements include a plurality of linear ridges/valleys such that the angles formed by such linear ridges/valley and a plane including at least one of the edge surfaces of the light emitting element is an acute angle; or the grid of protruding element include a plurality of annular ridges/valley centered about the central axis, and a plurality of linear ridges/valleys disposed radially around the central axis.