LED illumination system with polarization recycling

• US 8,075,140 B2
• Filed: 07/02/2007
• Issued: 12/13/2011
• Est. Priority Date: 07/31/2006
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Phillips, William E. III, English, Ronald E. Jr., Destain, Patrick R.
• Primary Examiner(s): Lee, John R
• Application Number:
  US11/772,609
• Publication Number:
  US 20090116214A1
• Time in Patent Office: 1,625 Days
• Field of Search: 353/20, 353/37, 353/38, 362/341, 359/483, 359/641, 359/742
• US Class Current: 353/20
• CPC Class Codes: G02B 13/001 Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras G02B23/243 takes precedence
• CPC Class Codes: G02B 13/0015 characterised by the lens design
• CPC Class Codes: G02B 13/0055 employing a special optical element
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 27/288 Filters employing polarising elements, e.g. Lyot or Solc filters G02B5/3016 takes precedence
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G03B 21/20 Lamp housings
• CPC Class Codes: G03B 21/204 using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A light engine has a light source front surface that emits non-collimated light. A collection lens collects the non-collimated light and provides incompletely collimated light. A collimating lens receives the incompletely collimated light and provides a collimated image. A non-orthogonal polarizing filter receives the collimated image and passes a polarized portion of the collimated image as a direct component of the polarized light engine image. The non-orthogonal polarizing filter reflects a recycled image back to the front surface. The non-orthogonal shape of the polarizing filter is selected according to the pattern of light on the light source front surface.

Claims

1. A light engine that provides a polarized light engine image, comprising:

a light source that has a front surface comprising a first region and a second region;

a collection lens that collects the non-collimated light from the front surface and that provides incompletely collimated light from the front surface;

a collimating lens that receives the incompletely collimated light and that provides a substantially collimated image of the front surface;

a polarizing filter that receives the collimated image of the front surface, the polarizing filter passing a polarized portion of the collimated image as a direct component of the polarized light engine image, and the polarizing filter reflecting a recycled image back to the front surface, the front surface providing the recycled image as a recycled component of the polarized light engine image; and

the polarizing filter comprising a non-orthogonal shape that shifts portions of the recycled component relative to the direct component, to increase brightness uniformity of the polarized light engine image.

2. The light engine of claim 1 wherein the non-orthogonal shape of the polarizing filter is selected from the group of a tilted polarizing filter shape and a curved polarizing filter shape.

3. The light engine of claim 1 wherein the filter shape comprises a curved, convex face that faces the collimating lens.

4. The light engine of claim 1 wherein the first region comprises an array of light emitting diodes.

5. The light engine of claim 4 wherein the array of light emitting diodes emit white light.

6. The light engine of claim 4 wherein the array of light emitting diodes sequentially emit red, green and blue light.

7. The light engine of claim 1 wherein the collection lens and the light source are combined in an encapsulated light emitting diode ball lens.

8. The light engine of claim 1 wherein the collimating lens comprises at least one Fresnel lens.

9. The light engine of claim 1 wherein the collimating lens comprises at least one convex lens.

10. The light engine of claim 1 wherein the first region includes a light emitting diode that emits a pattern of optical brightness that is off-center relative to a light emitting diode center, and the non-orthogonal polarizing filter improves centering of the polarized light engine image.

11. The light engine of claim 1 wherein at least one of the first and second regions comprises a phosphor.

12. The light engine of claim 1 wherein the second region comprises a reflective surface.

13. The light engine of claim 1 wherein the light engine image has substantially the same size as the collimated image.

14. The light engine of claim 1 wherein the light engine image comprises a collimated image.

15. The light engine of claim 1 and further comprising a quarter wave plate disposed between the light source and the polarizing filter.

16. The light engine of claim 1 wherein the substantially collimated image of the front surface comprises recycled light.

17. The light engine of claim 1 wherein the light engine does not include a light tunnel.

18. The light engine of claim 1 wherein the recycled image comprises an autocollimated image relative to the front surface.

19. The light engine of claim 1 wherein the collection lens, the collimating lens, the polarizing filter, and the polarized light engine image are aligned along a common optical axis.

20. The light engine of claim 1 wherein the polarizing filter comprises multilayer optical polarizing film.

21. The light engine of claim 1 wherein the light source and the collection lens are portions of a light emitting diode compound encapsulant lens.

22. A light engine that provides a polarized light engine image, comprising:

a light source that emits non-collimated light;

a collection lens that collects the non-collimated light and that provides incompletely collimated light of the front surface;

a collimating lens that receives the incompletely collimated light and that provides a collimated image of the front surface;

a non-orthogonal polarizing filter that receives the collimated image of the front surface, the polarizing filter passing a polarized portion of the collimated image as a direct component of the polarized light engine image, and the polarizing filter reflecting a recycled image back to the front surface;

the front surface providing the recycled image as a recycled component of the polarized light engine output; and

a quarter wave plate between the polarizing filter and the light source.