Patent ID: 9477116
Filing Date: 2016-10-25
CPC Classification: G02B,G02F

Claim Text:
1. A surface light source device comprising: a light emitting device including a light emitting element, and a light flux controlling member configured to control a distribution of light emitted from the light emitting element, the light flux controlling member being disposed over the light emitting element; and a light diffusion member configured to allow light emitted from the light emitting device to pass therethrough while diffusing the light, wherein the light flux controlling member comprises: an incidence surface configured such that light emitted from the light emitting element is incident on the incidence surface, the incidence surface comprising an outer incidence surface formed as an inclining surface such that a distance from the light emitting element increases as a distance from an optical axis of the light emitted from the light emitting element increases, and an inner incidence surface connected with an inside of the outer incidence surface, a reflection surface configured to laterally reflect the light incident on the incidence surface, the reflection surface being disposed on a side of the light flux controlling member opposite to the incidence surface such that a distance from the light emitting element increases in a direction from a center to an outer periphery of the reflection surface, and an emission surface configured to emit the light reflected by the reflection surface, the emission surface being disposed to surround the optical axis, wherein light emitted from a light emitting surface center of the light emitting element does not reach the inclining surface, and wherein light emitted from the light emitting surface center and travelling toward an area inside an outer edge of the inner incidence surface is incident on the inner incidence surface, and light emitted from the light emitting surface center and travelling toward an area outside the outer edge of the inner incidence surface reaches the light diffusion member without passing through the light flux controlling member.