Patent ID: 8008850

Claim:
A color temperature tunable white light-emitting device, comprising: a substrate; an ultraviolet light-emitting diode (UV LED) disposed over the substrate, electrically connected to the substrate, wherein the UV LED has a first emission surface for emitting ultraviolet (UV) light; a purple light-emitting diode (purple LED) disposed over the substrate, electrically connected to the substrate, wherein the purple LED has a second emission surface for emitting purple light; a blue light-emitting diode (blue LED) disposed over the substrate, electrically connected to the substrate, wherein the blue LED has a third emission surface for emitting blue light; a phosphor layer covering the UV LED, the purple LED, and the blue LED, wherein the phosphor layer is formed by blending phosphors of the at least two different colors in a transparent optical resin, and the phosphors are excited by the UV light from the UV LED and the purple light from the purple LED to thereby emit visible light, and combing the blue light from the blue LED to emit white light; an omni-directional reflector disposed over the phosphor layer and opposite to the first emission surface of the UV LED, the second emission surface of the purple LED, and the third emission surface of the blue LED; a medium layer disposed between the omni-directional reflector and the phosphor layer, wherein the medium layer has a refractive index that is less than a refractive index of the phosphor layer and the omni-directional reflector; a transparent substrate disposed over the omni-directional reflector, wherein the transparent substrate has opposite first and second surfaces, and the first surface of the transparent substrate is in contact with the omni-directional reflector; and an optical diffuser disposed over the second surface of the transparent substrate.