Patent ID: 7891852
Filing Date: 2011-02-22
Classification: G02B

Abstract:
1. An illumination system, the illumination system comprising: one or more light emitting diodes (LEDs) producing a first light; a hollow light-mixing zone, the hollow light-mixing zone being coupled to the one or more LEDs, the hollow light-mixing zone comprising multiple reflective walls that internally reflect the first light emitted by the one or more LEDs multiple times such that the first light reflected off the reflective walls is mixed within the hollow light-mixing zone, the reflective walls being formed of a non-transparent reflective material, wherein total internal reflection (TIR) is not used in the hollow light-mixing zone; a wavelength-converting layer coupled to an output of the hollow light-mixing zone, the hollow light-mixing zone being configured to substantially uniformly distribute the first light over the wavelength-converting layer by the multiple reflective walls reflecting and mixing the first light, the wavelength-converting layer converting the first light to a secondary light, the wavelength-converting layer containing a phosphor and the secondary light being a white light, the wavelength-converting layer having a surface facing the output of the hollow light-mixing zone, the multiple reflective walls being positioned to reflect the first light emitted by each LED at a plurality of angles with respect to the surface of the wavelength-converting layer such that reflected first light impinges on the surface of the wavelength-converting layer at a variety of angles, the hollow light-mixing zone comprising a light incident surface and at least three reflective walls, the reflective walls comprising a first reflective wall being substantially parallel with the wavelength-converting layer and being located opposite to the wavelength-converting layer, a second reflective wall being substantially perpendicular to the wavelength-converting layer, and a third reflective wall being substantially perpendicular to the wavelength-converting layer and opposing the second reflective wall, wherein the first reflective wall, the second reflective wall, and the third reflective wall have identical reflection characteristics, wherein the first, second and third reflective walls are perpendicular to the light incident surface; and a light-transmitting zone for redirecting the secondary light, the light-transmitting zone comprising: a transmitting surface; a first tapered surface; and a first flat surface, wherein the secondary light exits the light-transmitting zone from the transmitting surface, wherein the first flat surface is in a first plane adjacent to a second plane of the first tapered surface, wherein the first flat surface receives the secondary light from the wavelength-converting layer, and wherein the first reflective wall of the hollow light-mixing zone, the wavelength-converting layer and the first flat surface are parallel to each other; and wherein the at least one of the LEDs is located between the first reflective wall and the wavelength-converting layer and disposed adjacent to the outside of the light incident surface to direct light into the hollow light-mixing zone, wherein the wavelength-converting layer is located at the first flat surface of the light-transmitting zone, wherein the first flat surface of the light-transmitting zone is adjacent to the first tapered surface.