Light flux controlling member, light emitting device, surface light source device, display device, and method for improving luminance unevenness of light emitting device

A light flux controlling member for controlling a distribution of light emitted from n light emitting elements disposed on a substrate, the light flux controlling member comprising:

• n incidence units for allowing incidence of the light emitted from the n light emitting elements, respectively;
• an emission unit disposed between the n incidence units in a direction along the substrate, the emission unit allowing emission of the light incident on the n incidence units while guiding the light;
• and
• a plurality of legs disposed on a back side of the light flux controlling member, the plurality of legs supporting the light flux controlling member with respect to the substrate;
• wherein each of the n incidence units includes:
• an incidence surface disposed on the back side of the light flux controlling member, the incidence surface allowing incidence of the light emitted from the light emitting element, and
• a reflection surface disposed at a position on a front side of the light flux controlling member, the position facing the light emitting element with the incidence surface interposed between the reflection surface and the light emitting element, the reflection surface reflecting, in a lateral direction, the light incident on the incidence surface in such a way that the reflected light travels away from an optical axis of the light emitting element,
• wherein the emission unit includes:
• a first emission surface disposed on the front side of the light flux controlling member, the first emission surface reflecting a first part of the light from the incidence unit and emitting a second part of the light from the incidence unit, and
• a second emission surface disposed on the back side of the light flux controlling member so as to face away from the first emission surface, the second emission surface reflecting a third part of the light from the incidence unit and emitting a fourth part of the light from the incidence unit, and
• wherein each of the plurality of legs is disposed at a position satisfying condition 1 or 2 below:
• condition 1:
• with the light flux controlling member in plan view, at least a part of the leg is disposed outside a first region surrounded by 2n straight lines obtained by drawing two straight lines from a center of each of the n incidence units, the two straight lines being at respective angles of +(60/n)° and −(60/n)° with respect to a center of gravity of a polygonal formed by connecting the respective centers of the n incident units,
• condition 2:
• all of the leg is disposed inside a second region where light defined by a) to c) below substantially does not reach, the light defined by a) to c) being of light emitted from a light emitting center and incident on the incident surface, and being as follows:
• a) light that is reflected by no surface except for the reflection surface after reaching the reflection surface directly from the incidence surface and being reflected by the reflection surface, b) light that is reflected by no surface except for the reflection surface or the first emission surface after reaching the reflection surface directly from the incidence surface and being sequentially reflected by the reflection surface and the first emission surface, and c) light that is reflected by no surface except for the first emission surface after reaching the first emission surface directly from the incidence surface and being reflected by the first emission surface, the light emitting center being an intersection at a light emitting surface of the light emitting element with a central axis of the incidence unit.