Patent ID: 7915627

Claim:
A light emitting device comprising: a planar waveguide having a light emitting surface and an opposite surface, where the light emitting surface has disposed thereon a layer of phosphor material with an array of window areas; an edge-lighting unit positioned adjacent to at least one peripheral edge of the planar waveguide, the edge-lighting unit comprising at least one source of excitation radiation; wherein the excitation radiation having a first wavelength is coupled into the planar waveguide in a direction parallel to the light emitting surface, the planar waveguide configured such that the excitation radiation changes direction 90 degrees via total internal reflections within the waveguide such that it exits the planar waveguide perpendicular to the light emitting surface; and wherein the light emitted by the device comprises unabsorbed first wavelength radiation transmitted through the phosphor layer window areas, and second, longer wavelength photoluminescent light emitted by the phosphor layer as a result of excitation by the source.