Patent attributes
A layered light guide structure has a number of planar light guides arranged in a stack to receive a number of different color light beams from the edge of the light guides. Each of the planar light guides has one or more diffractive structures imparted or provided on its upper surface. The diffractive structures on each light guide are configured to diffract light of a particular wavelength range so that they efficiently diffract the guided light within that light guide. The diffractive structure can be one or more keypad symbols such that the layered light guide structure can be used as a keypad. The symbols can be pixelized such that the pixels can have different color patterns. The diffractive structure can also be a simple patch so that the layered light guide structure can be used as a back-light source.
