Light emitting diode (LED) lighting systems including low absorption, controlled reflectance and diffusion layers

1. A light emitting diode (LED) lighting system comprising:

a plurality of LEDs of at least two different colors;

a reflective layer configured so that at least some of the light of at least two different colors impinges on and emerges through the reflective layer, the reflective layer having a transmittance-to-reflectance ratio that is configured to homogenize intensity of the light that emerges through the reflective layer; and

a diffusion layer on the reflective layer opposite the plurality of LEDs so that at least some of the light that emerges from the reflective layer impinges on and emerges through the diffusion layer, the diffusion layer configured to homogenize color uniformity of the light that emerges from the reflective layer.

2. An LED lighting system according to claim 1 wherein the reflective layer has less than about 10% total absorption of the light that impinges thereon.

3. An LED lighting system according to claim 1 wherein the diffusion layer has less than about 15% total absorption of the light that impinges thereon.

4. An LED lighting system according to claim 1 wherein the reflective layer comprises a microcellular layer having a mean cell diameter of less than about 10 μm.

5. An LED lighting system according to claim 1 wherein the reflective layer comprises a microporous layer.

6. An LED lighting system according to claim 1 wherein the reflective layer comprises a layer of microcellular polyethylene terephthalate (MCPET) and/or a layer of Diffuse Light Reflector (DLR) material.

7. An LED lighting system according to claim 1 wherein the reflective layer has a transmittance-to-reflectance ratio that varies at different locations thereof, so as to homogenize the intensity of the light that emerges through the reflective layer.

8. An LED lighting system according to claim 6 wherein the layer of MCPET and/or DLR material is of variable thickness at different locations thereof to provide the transmittance-to-reflectance ratio that varies at different locations thereof, so as to homogenize the intensity of the light that emerges through the reflective layer.

9. An LED lighting system according to claim 6 wherein the layer of MCPET and/or DLR material includes a non-uniform array of holes extending therethrough to provide the transmittance-to-reflectance ratio that varies at different locations thereof, so as to homogenize the intensity of the light that emerges through the reflective layer.

10. An LED lighting system according to claim 1 wherein the diffusion layer comprises a random array of light diffusing features.

11. An LED lighting system according to claim 6 wherein the diffusion layer comprises a random array of light diffusing features.

12. An LED lighting system according to claim 11 wherein the random array of light diffusing features comprises a randomly spaced and/or sized microlens array.

13. An LED lighting system according to claim 1 wherein plurality of LED's comprise a planar array of LED's and wherein the reflective layer and the diffusion layer are planar layers.

14. An LED lighting system according to claim 1 wherein the LED lighting system is an LR-24 architectural luminaire.

15. An LED lighting system according to claim 1 wherein the LED lighting system further conforms to the ENERGY STAR Program Requirements for Solid State Lighting Luminaires.

16. An LED lighting system according to claim 1 wherein the plurality of LEDs of at least two different colors comprise at least one white LED and at least one red LED.

17. An LED lighting system according to claim 1 wherein the plurality of LEDs of at least two different colors comprise at least one blue shifted yellow LED and at least one red LED.

18. An LED lighting system according to claim 7 wherein the reflective layer is a first reflective layer, the LED lighting system further comprising a second reflective layer on the first reflective layer, wherein the second reflective layer has a transmittance-to-reflectance ratio that varies at different locations thereof differently than that of the first reflective layer.

19. An LED lighting system according to claim 9 wherein the layer of MCPET and/or DLR material is a first layer MCPET and/or DLR material and wherein the non-uniform array of holes extending therethrough is a first non-uniform array of holes extending therethrough, the LED lighting system further comprising:

a second layer of MCPET and/or DLR material on the first layer of MCPET and/or DLR material that includes a second non-uniform array of holes extending therethrough, wherein the first and second arrays are not congruent to each other.

20. A light emitting diode (LED) lighting system comprising:

an enclosure that comprises an enclosure floor, an enclosure ceiling and at least one enclosure wall therebetween;

a substrate adjacent the enclosure floor;

a plurality of LEDs of at least two different colors on the substrate facing the enclosure ceiling;

the enclosure ceiling comprising:

a reflective layer configured so that at least some of the light of at least two different colors impinges on and emerges through the reflective layer, the reflective layer having a transmittance-to-reflectance ratio that is configured to homogenize intensity of the light that emerges through the reflective layer; and

a diffusion layer on the reflective layer opposite the plurality of LEDs so that at least some of the light that emerges from the reflective layer impinges on and emerges through the diffusion layer, the diffusion layer configured to homogenize color uniformity of the light that emerges from the reflective layer.

21. An LED lighting system according to claim 20 wherein the reflective layer has less than about 10% total absorption of the light that impinges thereon.

22. An LED lighting system according to claim 20 wherein the diffusion layer has less than about 15% total absorption of the light that impinges thereon.

23. An LED lighting system according to claim 20 wherein the reflective layer comprises a microcellular layer having a mean cell diameter of less than about 10 μm.

24. An LED lighting system according to claim 20 wherein the reflective layer comprises a microporous layer.

25. An LED lighting system according to claim 20 wherein the reflective layer comprises a layer of microcellular polyethylene terephthalate (MCPET) and/or a layer of Diffuse Light Reflector (DLR) material.

26. An LED lighting system according to claim 20 wherein the reflective layer has a transmittance-to-reflectance ratio that varies at different locations thereof, so as to homogenize the intensity of the light that emerges through the reflective layer.

27. An LED lighting system according to claim 25 wherein the layer of MCPET and/or DLR material is of variable thickness at different locations thereof to provide the transmittance-to-reflectance ratio that varies at different locations thereof, so as to homogenize the intensity of the light that emerges through the reflective layer.

28. An LED lighting system according to claim 25 wherein the layer of MCPET and/or DLR material includes a non-uniform array of holes extending therethrough to provide the transmittance-to-reflectance ratio that varies at different locations thereof, so as to homogenize the intensity of the light that emerges through the reflective layer.

29. An LED lighting system according to claim 20 wherein the diffusion layer comprises a random array of light diffusing features.

30. An LED lighting system according to claim 25 wherein the diffusion layer comprises a random array of light diffusing features.

31. An LED lighting system according to claim 30 wherein the random array of light diffusing features comprises a randomly spaced and/or sized microlens array.

32. An LED lighting system according to claim 20 wherein the enclosure wall and/or the enclosure floor also comprise MCPET and/or DLR material.

33. An LED lighting system according to claim 20 wherein the LED lighting system is an LR-24 architectural luminaire.

34. An LED lighting system according to claim 20 wherein the LED lighting system further conforms to the ENERGY STAR Program Requirements for Solid State Lighting Luminaires.

35. An LED lighting system according to claim 20 wherein the plurality of LEDs of at least two different colors comprise at least one white LED and at least one red LED.

36. An LED lighting system according to claim 20 wherein the plurality of LEDs of at least two different colors comprise at least one blue shifted yellow LED and at least one red LED.

37. An LED lighting system according to claim 26 wherein the reflective layer is a first reflective layer, the LED lighting system further comprising a second reflective layer on the first reflective layer, wherein the second reflective layer has a transmittance-to-reflectance ratio that varies at different locations thereof differently than that of the first reflective layer.

38. An LED lighting system according to claim 28 wherein the layer of MCPET and/or DLR material is a first layer MCPET and/or DLR material and wherein the non-uniform array of holes extending therethrough is a first non-uniform array of holes extending therethrough, the LED lighting system further comprising:

a second layer of MCPET and/or DLR material on the first layer MCPET and/or DLR material that includes a second non-uniform array of holes extending therethrough, wherein the first and second arrays are not congruent to each other.

39. A light emitting diode (LED) lighting system comprising:

a plurality of LEDs of at least two different colors;

a first layer comprising microcellular polyethylene terephthalate (MCPET) and/or Diffuse Light Reflector (DLR) material configured so that at least some of the light of two different colors impinges on and emerges through the first layer; and

a second layer comprising a randomly spaced and/or sized array of light diffusing features on the first layer opposite the plurality of LEDs so that at least some of the light that emerges from the first layer impinges on and emerges through the second layer.

40. An LED lighting system according to claim 39 wherein the first layer has a transmittance-to-reflectance ratio that varies at different locations thereof.

41. An LED lighting system according to claim 40 wherein the first layer is of variable thickness at different locations thereof to provide a transmittance-to-reflectance ratio that varies at different locations thereof.

42. An LED lighting system according to claim 40 wherein the first layer includes a non-uniform array of holes extending therethrough to provide a transmittance-to-reflectance ratio that varies at different locations thereof.

43. An LED lighting system according to claim 39 wherein the light diffusing features comprises a microlens array.

44. An LED lighting system according to claim 39 wherein the LED lighting system is an LR-24 architectural luminaire.

45. An LED lighting system according to claim 39 wherein the LED lighting system further conforms to the ENERGY STAR Program Requirements for Solid State Lighting Luminaires.

46. An LED lighting system according to claim 39 wherein the plurality of LEDs of at least two different colors comprise at least one white LED and at least one red LED.

47. An LED lighting system according to claim 39 wherein the plurality of LEDs of at least two different colors comprise at least one blue shifted yellow LED and at least one red LED.

48. An LED lighting system according to claim 40 further comprising a third layer comprising MCPET and/or DLR material on the first layer, wherein the third layer has a transmittance-to-reflectance ratio that varies at different locations thereof differently than that of the first layer.

49. An LED lighting system according to claim 42 wherein the non-uniform array of holes is a first non-uniform array of holes extending therethrough, the LED lighting system further comprising:

a third layer comprising MCPET and/or DLR material on the first layer and that includes a second non-uniform array of holes extending therethrough, wherein the first and second arrays are not congruent to each other.