LED light source with field-of-view-controlling optics

• US 6,603,243 B2
• Filed: 03/06/2001
• Issued: 08/05/2003
• Est. Priority Date: 03/06/2000
• Status: Expired due to Fees

• Current Assignee: Teledyne Lighting & Display Products, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: Teledyne Technologies Incorporated
• Inventors: Pelka, David G., Parkyn, William A.
• Primary Examiner(s): Martin, David
• Assistant Examiner(s): Levi, Dameon E.
• Application Number:
  US09/800,073
• Publication Number:
  US 20020017844A1
• Time in Patent Office: 882 Days
• Field of Search: 313/110-113, 313/116, 313/512, 313/501, 313/114, 362/231, 362/297, 362/328, 362/346, 362/347, 362/356, 362/800, 362/296, 359/850, 359/853
• US Class Current: 313/113
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

Pixels for a large video display which employs solid-state emitters, such as colored light emitting diodes, as light source are formed by outfitting each colored solid state emitter within the pixel with an individually tailored miniature intensity-enhancing optical system. Each of these miniature optical systems comprises a set of four wide field-of-view Lambertian reflectors 34, a pair of narrow field-of-view Lambertian reflectors 36, and a beam-shaping lens 38. The miniature intensity-enhancing optical system can be specifically designed to restrict emission in the vertical field-of-view, while providing a Lambertian intensity dependence throughout an unrestricted horizontal view. For example, the field-of-view in the vertical direction may be limited to about ±30° while the field-of-view is about ±90° in the horizontal direction.

Claims

1. A color display comprising a plurality of pixels, each pixel comprising a plurality of light sources, each of said light sources comprising a solid-state emitter that emits light of a color different from other of said light sources, and each of said light sources including optics such that intensity variations with respect to view angle are substantially the same as other of said plurality of light sources;

wherein said light sources each comprise a light-emitting diode; and

wherein said optics for at least two of said light-emitting diodes in each of said pixels are dissimilar.

2. A color display of claim 1, wherein said optics have a configuration such that intensity variations with respect to view angle are substantially the same for each of light sources within said color display.

3. The color display of claim 1 wherein said optics comprise optical surfaces and wherein said surfaces for at least two of said light-emitting diodes in said pixels have substantially dissimilar curvatures.

4. A color display comprising a plurality of pixels each comprising a plurality of light sources, wherein said light sources each comprise a light-emitting diode and beam-shaping optics;

wherein said beam-shaping optics for at least two of said light-emitting diodes in each of said pixels are dissimilar.

5. The color display of claim 4, wherein said plurality of light sources are arranged linearly along a first direction within said pixel and said beam-shaping optics comprise reflective elements that reduce divergence of light to a limited range of angles in said first direction in comparison with divergence of light in a second orthogonal direction.

6. The color display of claim 5, wherein said beam-shaping optics comprises reflective optics shaped to provide a substantially cosine fall-off in said first direction.

7. The color display of claim 5, wherein said beam-shaping optics comprises refractive optics shaped to provide a substantially cosine fall-off in said second orthogonal direction and a substantially cosine fall-off in said first direction within said limited range of angles.

8. The color display of claim 5, wherein said first direction comprises a vertical direction and said second direction comprises a horizontal direction.

9. The color display of claim 8, wherein said reflective elements are shaped so as to restrict the divergence of light in said vertical direction to a range of angles spanning about 60°

.

10. A color display comprising a plurality of pixels each comprising a plurality of substantially Lambertian sources, each Lambertian source comprising a light-emitting diode that emits light of a color different from other of said Lambertian sources in said pixel and optics situated to receive light from said light-emitting diode and configured to redirect said light into a Lambertian output;

wherein said optics for at least two of said light-emitting diodes in each of said pixels are dissimilar.

11. The color display of claim 10, wherein said optics comprise a Lambertianizing cup comprising a plurality of reflectors shaped to distribute said light from said source in conformance with Lambert'"'"'s Cosine Law.

12. The color display of claim 11, further comprising reflectors that restrict divergence of said light in the one direction.

13. An apparatus comprising a light source which emits light for viewing at various angles, said light source comprising:

an LED having a front surface, a back surface opposite said front surface, and four side surfaces, wherein said front surface and said four side surfaces emit light and wherein said front surface and said four side surfaces intersect along four upper edges, respectively; and

a Lambertianizing cup comprising a bottom surface and four reflector surfaces, one facing each of said four side surfaces of said light-emitting diode, at least one opposed pair of said reflector surfaces configured to provide a substantially cosine fall-off of light intensity as the viewing angle deviates from a viewing direction extending from the light source in a plane perpendicular to said side surfaces of said LED that said pair of reflector surfaces face;

wherein said reflector surfaces substantially coincide with a locus of points intersecting an arc that is translated along a line parallel to said upper edge of each of said four sides of said LED.

14. The apparatus of claim 13 wherein said arc is formed from a circle having a center on said upper edge.

15. The apparatus of claim 14, wherein said circle has a radius at least as long as a distance that separates said front surface from said back surface of said cup.

16. The apparatus of claim 15, wherein each of said reflector surfaces has one end that approaches said back surface of said cup.

17. The apparatus of claim 16, wherein each of said reflector surfaces has another end that extends to a plane containing said front surface of said LED.

18. The apparatus of claim 17, wherein each of said four reflector surfaces contacts two other reflector surfaces, thereby forming four seams in said Lambertianizing cup.

19. A nonimaging optical element comprising:

first and second reflectors positioned in spaced, facing relationship, each reflector comprising;

a middle section comprising a surface in the form of a parabolic cylinder which has a line focus; and

two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,

wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions.

20. Beam-shaping optics for shaping a beam emitted from a light-emitting diode, said optics comprising:

(a) a first set of reflectors positioned adjacent to sides of said light-emitting diode;

(b) a second set of reflectors oriented to limit beam divergence of light from said light-emitting diode to a limited range of angles in one plane, the second set of reflectors comprising;

first and second reflectors positioned in spaced, facing relationship, each reflector comprising;

a middle section comprising a surface in the form of a parabolic cylinder which has a line focus; and

two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,

wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions; and

(c) an optical element comprised of transmitting material positioned to receive light from said light-emitting diode and said first and second sets of reflectors, wherein said sets of reflectors and transmitting material are oriented and configured to provide a substantially Lambertian fall-off for light intensity in said one plane within said limited range of angles and a substantially Lambertian fall-off for light intensity in an orthogonal plane within a range of angles greater than said limited range of angles.

21. A method of manipulating light emitted from a light-emitting diode to provide a light source that substantially obeys Lambert'"'"'s cosine-law through a range of viewing angles, said method comprising the steps of:

collecting light emitted from plural side surfaces of a light-emitting diode and redirecting said light so that the light emitted by the light source approximates light emitted by a single Lambertian surface;

reducing the divergence of collected light in a plane orthogonal to an opposing pair of said plural sides by guiding the collected light through first and second reflectors positioned in spaced, facing relationship, each reflector comprising;

a middle section comprising a surface in the form of a parabolic cylinder which has a line focus; and

two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,

wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions; and

refracting collected light after reducing the divergence.

22. A method of shaping the output of a light-emitting diode having a front and a plurality of sides that emit light, said method comprising the steps of:

collecting light emitted from said sides and redirecting said light to simulate light produced by a single substantially Lambertian surface;

using reflectors to reduce the divergence of the beam in one direction to a limited range of angles while maintaining a substantially Lambertian fall-off within a substantial portion of said limited range, wherein the reflectors comprise first and second reflectors positioned in spaced, facing relationship, each reflector comprising;

a middle section comprising a surface in the form of a parabolic cylinder which has a line focus; and

two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,

wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions.