Patent ID: 7377678

Claim:
A backlight module, comprising: a diffuser; a reflector disposed under the diffuser; a side light source with a bottom for emitting light disposed on a side between the diffuser and the reflector, wherein the reflector extends to a bottom plane of the module from the bottom of the side light source and there is an elevation angle between the reflector and the bottom plane so that the light emitted from the side light source reflected by the reflector travels along a direction nearly parallel to the elevation angle; a prism lens disposed between the side light source and the reflector; wherein the prism lens further comprises: a main body; and a plurality of protruding parts formed on the main body and facing the side light source, wherein each of the protruding parts has a first plane substantially parallel to the diffuser and a second plane above the first plane, wherein an acute angle is formed between the first plane and the second plane so that the light passing through the prism lens is separated into downward light and upward light; and an air layer surrounded by the diffuser, the reflector and the prism lens, wherein while an incident angle of the light is increased to a predetermined degree, the light is reflected back to the air layer and is therefore sufficiently mixed.