Edge-lit waveguide illumination systems employing planar arrays of linear cylindrical lenses

1. An edge-lit waveguide illumination system, comprising:

an optically transmissive plate having a flexible monolithic structure, a front surface, an opposing back surface extending parallel to the front surface, a first edge, a second edge extending parallel to the first edge, a third edge extending perpendicular to the first and second edges, and a fourth edge extending parallel to the third edge, wherein a distance between the first and second edges is at least 40 times greater than a thickness of the optically transmissive plate and a distance between the third and fourth edges is at least 20 times greater than the thickness of the optically transmissive plate;

a plurality of light emitting diodes optically coupled to the first edge and configured to emit a divergent light beam towards the first edge;

a lenticular array of linear cylindrical lenses formed in the front surface and extending along straight parallel lines between two opposing edges of the optically transmissive plate;

a plurality of discrete light extracting surface relief features formed in the back surface according to a two-dimensional pattern such that individual ones of the plurality of the discrete light extracting surface relief features are separated from one another and from each of the first, second, third, and fourth edges by smooth and planar portions of the back surface;

a reflective surface approximately coextensive with the optically transmissive plate and positioned on a back side of the optically transmissive plate; and

a light diffusing layer approximately coextensive with the optically transmissive plate,

wherein the optically transmissive plate is configured to receive light on the first edge, guide the light received on the first edge towards the second edge using optical transmission and total internal reflection, and distribute the light received on the first edge from both the front and back surfaces towards divergent directions,

wherein the optically transmissive plate is further configured to receive light on the front surface and propagate the light received on the front surface towards the back surface,

wherein an area occupied by each of the linear cylindrical lenses is substantially greater than an area occupied by each of the plurality of the discrete light extracting surface relief features, and

wherein at least one of the plurality of discrete light extracting surface relief features is configured to disrupt total internal reflection at the back surface and extract at least some light propagated in the optically transmissive plate towards the reflective surface.

2. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least some of the discrete light extracting surface relief features have randomized positions within the two-dimensional pattern.

3. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least some of the plurality of discrete light extracting surface relief features are arranged in parallel rows and columns within the two-dimensional pattern.

4. An edge-lit waveguide illumination system as recited in claim 1 , further comprising a light filtering film.

5. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of the plurality of discrete light extracting surface relief features is configured to deflect at least some light using total internal reflection and direct the deflected light towards the linear cylindrical lenses at an angle of less than 42 degrees with respect to a normal to the back surface.

6. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of the plurality of discrete light extracting surface relief features comprises a cavity formed in the back surface and having a curved wall, wherein the curved wall is configured to deflect light using both total internal reflection and refraction.

7. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of the plurality of discrete light extracting surface relief features comprises a light scattering material and has a textured surface.

8. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of the plurality of discrete light extracting surface relief features comprises a light diffracting element.

9. An edge-lit waveguide illumination system as recited in claim 1 , further comprising one or more photoresponsive elements disposed in an energy receiving relationship with respect to the optically transmissive plate.

10. An edge-lit waveguide illumination system as recited in claim 1 , further comprising one or more light converting elements approximately coextensive with a surface of the optically transmissive plate and disposed in an energy receiving relationship with respect to the optically transmissive plate.

11. An edge-lit waveguide illumination system as recited in claim 1 , wherein the optically transmissive plate is configured to be bent or flexed without breaking.

12. An edge-lit waveguide illumination system as recited in claim 1 , wherein the optically transmissive plate is retained in a bent or curved configuration.

13. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of the plurality of light emitting diodes is configured to emit monochromatic light.

14. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of the light emitting diodes is a side-emitting LED attached to a planar finless heat sink, wherein the planar finless heat sink is oriented parallel to the optically transmissive plate and comprises a layer of a metallic material, and wherein a light emitting surface of the side-emitting LED is oriented perpendicular to a prevalent plane of the planar finless heat sink.

15. An edge-lit waveguide illumination system as recited in claim 1 , wherein at least one of said light emitting diodes is a side-emitting LED attached to a planar heat-spreading substrate, wherein the planar heat-spreading substrate is oriented parallel to the optically transmissive plate and perpendicular to a light emitting surface of the side-emitting LED.

16. An edge-lit waveguide illumination system as recited in claim 1 , wherein a focal length characterizing at least one of the linear cylindrical lenses is less than a distance between the lenticular array and the plurality of discrete light extracting surface relief features.

17. An edge-lit waveguide illumination system as recited in claim 1 , further comprising a reflective film laminated to the second edge.

18. An edge-lit waveguide illumination system as recited in claim 1 , further comprising a reflective film laminated to each of the second, third, and fourth edges.

19. A method of making an edge-lit waveguide illumination system, comprising the steps of:

providing a planar monolithic plate of a rectangular shape from a highly transparent dielectric material at a thickness that is at least 40 times less than a major dimension of the planar monolithic plate;

forming a parallel array of linear cylindrical lenses in a front surface of the planar monolithic plate such that each of the linear cylindrical lenses extends between two opposing edges of the planar monolithic plate;

forming a two dimensional pattern of discrete light extracting surface relief features in an opposing second surface of the planar monolithic plate such that the discrete light extracting surface relief features are separated from one another and from all perimeter edges of the planar monolithic plate by smooth and planar portions of the second surface;

positioning a reflective film on a side of the second surface of the planar monolithic plate;

positioning a light diffusing layer parallel to the planar monolithic plate; and

optically coupling a plurality of light emitting diodes to a light input edge of the planar monolithic plate.

20. A method of making an edge-lit waveguide illumination system as recited in claim 19 , wherein the planar monolithic plate is curved.

21. A method of making an edge-lit waveguide illumination system as recited in claim 19 , further comprising a step of bending the planar monolithic plate into a curved shape.

22. A method of making an edge-lit waveguide illumination system as recited in claim 19 , further comprising a step of laminating a reflective film to an edge of the planar monolithic plate.

23. A method of making an edge-lit waveguide illumination system as recited in claim 19 , further comprising a step of polishing an edge of the planar monolithic plate.

24. A method for illuminating a display screen comprising:

receiving light into a light input edge of a planar optical waveguide having edges disposed between a first planar microstructured surface and an opposing second planar microstructured surface extending parallel to the first planar microstructured surface, wherein the first planar microstructured surface defines a parallel array of linear cylindrical lenses extending along straight lines between two opposite edges of the planar optical waveguide, and wherein the second planar microstructured surface comprises a two-dimensional pattern of discrete light extraction surface relief features separated from one another and from the edges by smooth and planar portions of the second planar microstructured surface;

propagating the light by optical transmission and total internal reflection in an optical material disposed between the first planar microstructured surface and the second planar microstructured surface along a direction perpendicular to the light input edge, wherein the optical material has a thickness that is at least 40 times less than a length or width dimension of the second planar microstructured surface;

extracting the light from the planar optical waveguide using the two-dimensional pattern of discrete light extraction surface relief features disrupting total internal reflection and causing the light to exit the optical waveguide through the first planar microstructured surface and the second planar microstructured surface;

reflecting at least a portion of the light exiting through the second planar microstructured surface using a reflective surface extending parallel to and approximately coextensive with the second planar microstructured surface; and

distributing the light through the parallel array of linear cylindrical lenses towards the display screen as a divergent beam.