Patent ID: 8328406

Claim:
An illumination structure comprising: a first substantially flat waveguide for propagating and emitting light, the first waveguide comprising one or more optical elements for coupling light out of the first waveguide; a second substantially flat waveguide disposed beneath the first waveguide and defining an interface therebetween, the second waveguide comprising (i) an in-coupling region for receiving light from a discrete light source and (ii) surrounding the in-coupling region, a propagation region for retaining therein and spreading therethrough light from the in-coupling region, the propagation region terminating in an edge through which light is emitted; and a perimeter reflector surrounding the first and second waveguides, the perimeter reflector reflecting light emerging from the edge of the propagation region of the second waveguide into the edge of the first waveguide, wherein (i) a first portion of light emitted by the discrete light source propagates from at least one of the in-coupling region or the propagation region into the first waveguide through the interface, (ii) a second portion of light emitted by the discrete light source is retained in the propagation region until emitted at the edge thereof, the perimeter reflector reflecting the second portion of the light into the first waveguide at an edge thereof, and (iii) light is emitted from a top surface of the first waveguide, an intensity of the emitted light being substantially uniform over the top surface.