Narrow angle light engine
A light engine includes a housing containing a rectangular aperture, a polarizer disposed in the housing facing the aperture, a light emitting diode (LED) array disposed in the housing, and a light guide configured to guide light emitted from the LED array toward the aperture, such that light is emitted through the aperture.
1. A light engine, comprising:
a housing comprising a rectangular aperture;
a polarizer disposed in the housing facing the aperture;
a micro-lensed, light emitting device disposed in the housing; and
a light guide comprising a collimating lens and configured to guide light emitted from the LED array toward the aperture, such that light is emitted through the aperture,
wherein the micro-lensed, light emitting device comprises:
a backplane disposed on the housing;
a two-dimensional array of pixel groups disposed on the backplane, each pixel group including light emitting diodes (LEDs) emitting light of different colors and spatially spaced apart among one another;
an encapsulation layer having a first refractive index and encapsulating the LEDs and continuously extending over each pixel group within the two-dimensional array of pixel groups;
an interlayer having a second refractive index and continuously extending over the encapsulation layer and the two-dimensional array of pixel groups; and
a two-dimensional array of micro-lenses disposed on the interlayer and configured to direct light from the two-dimensional array of pixel groups to the collimating lens, wherein:
the two-dimensional array of micro-lenses is arranged with a two-dimensional pattern such that each LED within any given pixel group is equidistant from a center line of a respective overlying micro-lens that directly overlies the given pixel group; and
the encapsulation layer, the interlayer, and the two-dimensional array of micro-lenses are configured to provide an emitting center for any given pixel group that is aligned with the center line of the respective overlying micro-lens and to reduce an emission angle for light that is emitted from each pixel group within the two-dimensional array of pixel groups and exits toward the collimating lens as substantially parallel beams along a direction substantially perpendicular to a top surface of the backplane.
2. The light engine of claim 1 , wherein the housing comprises a bottom and an open top, and a cover disposed on the top of the housing and comprising the rectangular aperture.
3. The light engine of claim 2 , wherein the polarizer comprises a polarizer sheet.
4. The light engine of claim 3 , wherein the light engine comprises a direct lit light engine.
5. The light engine of claim 4 , wherein:
the LED array is disposed on the bottom of the housing; and
the light guide comprises a collimating lens disposed in the housing between the LED array and the polarizing sheet.
6. The light engine of claim 5 , wherein the cover is configured to mask light output from the polarizing sheet, such that a substantially rectangular light spot is emitted by the light engine.
7. The light engine of claim 3 , wherein the light engine comprises an edge lit light engine.
8. The light engine of claim 7 , wherein the light guide comprises:
a reversed Fresnel lens as the collimating lens; and
a triangular prismatic main body comprising a first surface that faces the Fresnel lens, a third surface that is substantially perpendicular to the first surface, and a second surface configured to reflect light transmitted through the first surface towards the third surface.
9. The light engine of claim 8 , wherein the second surface comprises indentations configured to reflect light toward the third surface.
10. The light engine of claim 8 , wherein:
the reversed Fresnel lens is configured to collimate light received from the LED array onto the first surface of the main body; and
the LED array is disposed on a sidewall of the housing.
11. The light engine of claim 8 , wherein the third surface comprises a coating or surface features configured to increase light extraction from the main body.
12. The light engine of claim 3 , wherein:
the cover comprises supports extending from corners thereof;
the light guide comprises a lip disposed on an upper edge of the housing; and
portions of the lip are disposed in openings formed between the supports.
13. The light engine of claim 1 , wherein the LED array comprises LEDs that emit red, green, and blue light.
14. The light engine of claim 1 , wherein the aperture is square shaped.
15. The light engine of claim 1 , wherein the light source has:
a height ranging from about 5 mm to about 20 mm; and
a length and width ranging from about 10 mm to about 30 mm.
16. A display device comprising an imager and the light engine of claim 1 .
17. The display device of claim 16 , wherein the display device comprises smart glasses.
18. The display device of claim 16 , wherein the display device comprises virtual reality goggles.
19. A projector device comprising an imager and the light engine of claim 1 .
20. The projector device of claim 19 , wherein the projector device comprises a pico-projector.
21. The light engine of claim 1 , wherein the micro-lensed, light emitting device is configured such that each micro-lens receives at least 75% of light emitted from a respective one of the LEDs.
22. The light engine of claim 1 , wherein the micro-lensed, light emitting device is configured such that each micro-lens receives at least 75% of light emitted from a respective set of at least three of the LEDs.