Patent ID: 9671087
Date: 2017-06-06
CPC Classifications: F21K,F21V,F21Y

Claim:
1. An illumination apparatus comprising: at least one light emitting element that is disposed on a substrate and has an optical axis along a normal line to the substrate; a light flux controlling member disposed on the substrate to control a distribution of light emitted from the light emitting element; and a cover that covers at least the light emitting element and the light flux controlling member to transmit light emitted from the light flux controlling member while diffusing the emitted light, wherein the light flux controlling member includes a first light flux controlling member that is disposed to face the light emitting element, and a second light flux controlling member that is disposed to face the first light flux controlling member, wherein the first light flux controlling member includes an incidence surface for allowing a part of the light emitted from the light emitting element to enter the incidence surface, a total reflection surface for totally reflecting light, which reached directly from the incident surface, toward the second light flux controlling member, and an emission surface for emitting a part of the light having entered the incidence surface and the light reflected at the total reflection surface toward the second light flux controlling member, wherein the second light flux controlling member has a reflection surface that faces the emission surface of the first light flux controlling member to reflect a part of light having been emitted from the first light flux controlling member and having reached the second light flux controlling member and to transmit a rest of the light, wherein the reflection surface is a rotationally symmetrical plane around the optical axis as a rotation axis and is formed such that a generatrix line of the rotationally symmetrical plane is a concave curve relative to the first light flux controlling member, an outer peripheral portion of the reflection surface is disposed at a position distant from the light emitting element in a direction X of the optical axis compared with a center portion of the reflection surface, and wherein a ratio of R to O (R/O) is more than 0.33 and less than 1.2: where O represents a distance in the direction X from a point, which is the most distant from the substrate, on the light flux controlling member to a point, which is the most distant from the substrate, on an inner surface of the cover, and R represents, in a cross-section including the optical axis, a distance in a direction Y orthogonal to the optical axis from an intersection of a straight line orthogonal to the optical axis through an outermost edge portion of the total reflection surface and the inner surface of the cover to a point, which is the most distant from the optical axis, of the light flux controlling member.