Light emitting diode projection system

• US 7,832,878 B2
• Filed: 01/19/2007
• Issued: 11/16/2010
• Est. Priority Date: 03/06/2006
• Status: Active Grant

• Current Assignee: Innovations in Optics, Inc.
• Original Assignee: Innovations in Optics, Inc.
• Inventors: Demilo, Charles A., Brukilacchio, Thomas J.
• Primary Examiner(s): Dowling; William C
• Application Number:
  US11/655,313
• Publication Number:
  US 20070206390A1
• Time in Patent Office: 1,397 Days
• Field of Search: 353/31, 353/98, 353/99, 385/133, 385/901, 362/551, 362/555, 362/559, 362/561, 313/512
• US Class Current: 353/99
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0066 in the form of an LED array
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 27/1033 having a single light modulator for all colour channels
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• 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 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: Y10S 362/80 Light emitting diode
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

The present invention generally relates to video and/or television projection systems, and more particularly, to LED based light source systems utilizing generally non-rotationally symmetric, preferably oblong or rectangular, non-imaging collection optics for providing improved projection systems relative to arc lamp and other LED based light source systems. The non-rotationally symmetric non-imaging collection optics are configured to operate with LEDs to provide preferred, generally, uniform light distributions whose étendues match those of downstream applications such as those encountered in projection systems. Also provided are various arrangements for coupling LED output to the entrance aperture of collection optics and for coupling the outputs from a plurality of collection optic outputs to form single beams of illumination of preferred patterns, intensities, and color.

Claims

1. An illumination apparatus for providing an output beam that matches the é

tendue of a downstream application, said illumination apparatus comprising

at least one LED optical source having a predetermined é

tendue and spectral output; and

at least one non-imaging optic for collecting substantially all of the light emitted by said at least one LED optical source and re-emitting it as a beam of substantially the same é

tendue as that of said LED optical source, said non-imaging optic having an entrance aperture, an exit aperture, and a non-rotationally symmetric cross-sectional shape that continuously enlarges from said entrance to said exit aperture, said at least one LED optical source being positioned at and fully across said entrance aperture so that said entrance aperture is substantially uniformly filled by said output of said LED optical source, said output of said at least one LED optical source being directed by said non-imaging optic shape to emerge from said exit aperture as a beam having substantially the same é

tendue as that of said at least one LED optical source but altered in angle and dimensions to substantially match the é

tendue of the downstream application,

wherein said shape is rectangular to provide said beam with a near field that is also rectangular and wherein said non-imaging optic has at least two profiles of different shape as seen in planes mutually orthogonal to its longitudinal optical axis.

2. The illumination apparatus of claim 1 wherein the cross-sectional shape of said entrance and exit apertures of said non-imaging optic and the cross-sectional shape thereof is oblong.

3. The illumination apparatus of claim 1 wherein said rectangular shapes of said entrance and exit apertures differ in size and have the same aspect ratio.

4. The illumination apparatus of claim 1 wherein the far field of said beam is also rectangular.

5. The illumination apparatus of claim 1 wherein said non-imaging optic is solid being composed of a transmissive dielectric material.

6. The illumination apparatus of claim 5 wherein said at least one LED is coupled to said entrance aperture of said solid non-imaging optic with an index matching material.

7. The illumination apparatus of claim 5 wherein said at least one LED is optically coupled to said entrance aperture of said solid non-imaging optic by a non-index-matching material.

8. The illumination apparatus of claim 7 wherein said solid non-imaging optic comprises a first straight-walled section beginning with said entrance aperture and a second section having the shape of a CPC and ending with said exit aperture, said first straight walled-section and said second CPC section joining at an interface where they share common points of tangency so that said solid nonimaging optic can efficiently utilize the output of an LED that is larger than it otherwise could be without said conical section.

9. The illumination apparatus of claim 8 further including an entrance homogenizer optically coupled to said first straight-walled section and wherein said at least one LED is optically coupled to said entrance homogenizer without index matching.

10. The illumination apparatus of claim 1 wherein one of said two profiles is in the form of a CPC that runs the full length of said non-imaging optic while the other is in the form of a CPC of length shorter than the full length of said non-imaging optic.

11. The illumination apparatus of claim 10 wherein the longitudinal profile of said non-imaging optic varies as a function of the azimuthal angle looking along the optical axis to provide said beam with a far field that is substantially circular in shape.

12. The illumination apparatus of claim 1 further including a homogenizer having one end optically coupled to said input aperture of said non-imaging optic and one end optically coupled to said at least one LED.

27. The illumination apparatus of claim 7 wherein entrance aperture is enlarged compared with what it would otherwise be when index matched to said LED to increase the é

tendue of the downstream application.

13. A projection apparatus for forming video images, said projection apparatus comprising:

at least one LED optical source having a predetermined é

tendue and spectral output;

a digital device for selectively modulating light incident thereto, said digital device having a given é

tendue;

at least one non-imaging optic for collecting substantially all of the light emitted by said at least one LED optical source and re-emitting it as a spatially uniform beam of substantially the same é

tendue as that of said LED optical source, said non-imaging optic having an entrance aperture, an exit aperture, and a nonrotationally symmetric cross-sectional shape that continuously enlarges from said entrance to said exit aperture, said at least one LED optical source being positioned at and fully across said entrance aperture so that said entrance aperture is substantially uniformly filled by said output of said LED optical source, said output of said at least one LED optical source being directed by said non-imaging optical shape to emerge from said exit aperture as a beam having substantially the same é

tendue as that of said at least one LED optical source but altered in angle and dimensions to substantially match the é

tendue of said digital device;

a relay lens for imaging the near field from said non-imaging optic onto said digital device to form video images;

a screen for viewing images formed thereon; and

a projection lens for projecting said digital device onto said screen as said digital device is modulated so that video images formed thereon can be observed on said viewing screen,

wherein said relay lens images the far field of said beam from said non-imaging optic into the aperture stop of said projection lens.

14. The projection apparatus of claim 13 wherein said digital device is selected from the group consisting of rectangular shaped DMDs, LCOS chips, and LCD chips.

15. An illumination apparatus for providing an output beam that matches the &

endue of a downstream application, said illumination apparatus comprising

at least one LED optical source having a predetermined é

tendue and spectral output; and

at least one solid non-imaging optic for collecting substantially all of the light emitted by said at least one LED optical source and re-emitting it as a spatially uniform beam of substantially the same é

tendue as that of said LED optical source, said non-imaging optic having an entrance aperture, an exit aperture, and a rotationally symmetric cross-sectional shape that continuously enlarges from said entrance to said exit aperture, said at least one LED optical source being air spaced from and fully across said entrance aperture so that (said entrance aperture is substantially uniformly filled by said output of said LED optical source, said output of said at least one LED optical source being directed by said non-imaging optical shape to emerge from said exit aperture as a beam having substantially the same é

tendue as that of said at least one LED optical source but altered in angle and dimensions to substantially match the é

tendue of the downstream application,

wherein said at least one solid non-imaging optic comprises a first conical section beginning with said entrance aperture and a second section haying the shape of a CPC and ending with said exit aperture, said first conical section and said second CPC section transitioning at a cross-sectional location of said at least one non-imaging optic where they share common points of tangency so that said at least one solid non-imaging optic can efficiently utilize the output of an LED that is larger than it otherwise could be without said conical section.

16. The illumination apparatus of claim 15 further including a entrance homogenizer optically coupled to said first straight-walled section and wherein said at least one LED is optically coupled to said entrance homogenizer without index matching.

17. An LED apparatus comprising:

a bare LED die having an emitting surface that is at least in part diffusely reflective; and

a low absorption encapsulant conformally overlying said bare LED die, said low absorption encapsulant being formed of a material having an index of refraction greater than unity so as to operate to at least in part totally internally reflect light at the encapsulant air interface so that it impinges onto said diffusely reflective emitting surface after which it is at least in part transmitted back through said encapsulant air interface so that the overall output of said apparatus is increased over what it would otherwise be without said encapsulant.

18. The LED apparatus of claim 17 wherein said index of refraction of said encapsulant material is 1.5 or more and wherein the diffuse reflectivity of said emitting surface exceeds 50 percent.

19. An illumination apparatus for providing an output beam that matches the é

tendue of a downstream application, said illumination apparatus comprising

at least two LED optical sources having a predetermined é

tendue and different spectral output beams;

at least two non-imaging optics for collecting substantially all of the light emitted by said at least two LED optical source and re-emitting it as a beam of substantially the same é

tendue as that of said LED optical source, said non-imaging optic having an entrance aperture, an exit aperture, and a non-rotationally symmetric cross-sectional shape that continuously enlarges from said entrance to said exit aperture, said at least one LED optical source being positioned at and fully across said entrance aperture so that said entrance aperture is substantially uniformly filled by said output of said LED optical source, said output of said at least one LED optical source being directed by said non-imaging optic shape to emerge from said exit aperture as a beam having substantially the same é

tendue as that of said at least two LED optical sources but altered in angle and dimensions to substantially match the é

tendue of the downstream application,

a combiner for receiving the outputs from said beams from said at least two non-imaging optics having different spectral content and combining them for travel as a single beam whose content is a uniform mixture of the spectral content of both beams, and

a beam homogenizer for receiving said single beam emerging from said combiner, said homogenizer being tilted to compensate for keystoning effects.

20. The illumination apparatus of claim 19 wherein said combiner is configured and arranged to operate to pipe light therethrough in at least two directions.

21. The illumination apparatus of claim 19 wherein said combiner comprises an optical device selected from the group consisting of X-cubes, X-plates, beam splitters, transmission gratings, dynamic prisms with one selectively separable interface, dynamic prisms with two selectively separable interfaces, tilting mirrors, and rotating prisms.

22. The illumination apparatus of claim 19 wherein said homogenizer is hollow.

23. The illumination apparatus of claim 19 wherein said spectral content of said beams comprise R, G, B colors so that, when combined, they produce white light.

24. An illumination apparatus for providing an output beam that matches the é

tendue of a downstream application, said illumination apparatus comprising

at least one LED optical source having a predetermined é

tendue and spectral output;

at least one non-imaging optic for collecting substantially all of the light emitted by said at least one LED optical source and re-emitting it as a beam of substantially the same é

tendue as that of said LED optical source, said non-imaging optic having an entrance aperture, an exit aperture, and a non-rotationally symmetric cross-sectional shape that continuously enlarges from said entrance to said exit aperture, said at least one LED optical source being positioned at and fully across said entrance aperture so that said entrance aperture is substantially uniformly filled by said output of said LED optical source, said output of said at least one LED optical source being directed by said non-imaging optical-optic shape to emerge from said exit aperture as a beam having substantially the same é

tendue as that of said at least one LED optical source but altered in angle and dimensions to substantially match the é

tendue of the downstream application,

a digital device for selectively modulating light incident thereto; and

a relay lens for imaging the near field from said non-imaging optic onto said digital device to form video images, said relay lens imaging the far field of said beam from said non-imaging optic into the aperture stop of said projection lens.

25. The illumination apparatus of claim 24 wherein said digital device is selected from the group consisting of rectangular shaped DMDs, LCOS chips, and LCD chips.

26. The illumination apparatus of claim 24 further including a projection lens and a screen for projecting said digital device onto said screen as said digital device is modulated so that the video images formed thereon can be observed on said screen.