Patent ID: 8061884

Claim:
A light emitting device comprising: a light emitting diode (LED) die; a heat conductive submount on which the LED die is mounted, the submount having a top surface on which the LED die is mounted and a bottom surface opposing the top surface; a reflective cavity at least partially surrounding the LED die, the cavity having walls, the cavity having an opening for light to exit; and a substantially rectangular light guide formed of a solid material, the light guide having a top surface, a bottom surface, with remaining surfaces being side surfaces, the light guide adapted for supplying light as a backlight, the light guide emitting light through the top surface of the light guide, the light guide having a reflective film on its bottom surface for reflecting light through its top surface; the opening of the reflective cavity opposing a first one of the side surfaces of the light guide, the reflective cavity having walls with only one of the walls having an extension, wherein the one of the walls and the extension comprising a metal, the extension extending over a majority of the bottom surface of the light guide, but not extending over a majority of any of the side surfaces of the light guide, wherein the bottom surface of the submount is mounted on the one of the walls of the reflective cavity having the extension, and wherein the submount is thermally coupled to the extension so that the extension acts as a heat sink for the LED die.