Patent ID: 8203665

Claim:
A backlight unit, comprising: an optical source including a plurality of unit groups, each unit group having a plurality of light emitting diodes (LEDs), wherein each of the unit groups comprises one red (R) LED, one blue (B) LED, and two green (G) LEDs; a light mixing layer formed over the unit groups, for mixing lights emitted from the LEDs to provide substantially white light, wherein the light mixing layer is a double-layer structure including an inner layer and an outer layer, and a refractive index of the inner layer is larger than a refractive index of the outer layer to provide color mixture and brightness uniformity by total reflection at a boundary surface between the inner layer and the outer layer of the light mixing layer, and the light mixing layer has a semi-spherical shape to disperse R, G and B light and uniformly mix the dispersed R, G and B light, and is formed of a dispersion material, wherein the mixed dispersed R, G and B light is emitted outwardly through the light mixing layer, and the inner layer is formed of one of poly methyl methcrylate (PMMA), SK4, silica, epoxy and MgF, and the outer layer is formed of one of poly methyl methcrylate (PMMA), SK4, silica, epoxy, and MgF, wherein the inner layer and outer layer are formed of a different material from each other; and a reflector disposed under the optical source and the light mixing layer, wherein the LEDs are enclosed by the reflector and the light mixing layer, and each layer of the light mixing layer is in contact with the reflector.