Illumination device having a tapered light guide

• US 8,721,149 B2
• Filed: 07/31/2012
• Issued: 05/13/2014
• Est. Priority Date: 01/30/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Holman, Robert L., Sampsell, Matthew B.
• Primary Examiner(s): Green, Tracie Y
• Application Number:
  US13/563,377
• Publication Number:
  US 20120294037A1
• Time in Patent Office: 651 Days
• Field of Search: 362/609, 362/623, 362/621, 362/628, 362/612, 451/28, 359/485.06, 359/485.05
• US Class Current: 362/609
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0058 varying in density, size, shape or depth along the light guide
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: Y10T 156/1089 of discrete laminae to single face of additional lamina

Abstract

This disclosure provides systems, methods and apparatus for illumination devices. In one aspect, an illumination device having a longitudinal axis includes a light source and a light guide. The light guide has a peripheral edge, a transmissive illumination surface, a center portion, and an upper surface. The transmissive illumination surface is oriented perpendicular to the longitudinal axis and disposed between the center portion and the peripheral edge. The upper surface is oriented relative to the illumination surface to define an angle α therebetween. In some implementations, the angle α can be greater than 15 degrees, for example.

Claims

1. An illumination device, comprising:

a light source;

a light guide including

a peripheral edge disposed about a longitudinal axis of the illumination device

a center portion having a light entry surface through which light emitted from the light source propagates into the light guide

a transmissive illumination surface oriented perpendicular to the longitudinal axis and disposed between the center portion and the peripheral edge and

an upper surface disposed between the center portion and the peripheral edge, the upper surface oriented relative to the illumination surface to define an angle α

therebetween, wherein the angle α

is less than 15 degrees.

2. The device of claim 1, further comprising a reflective surface adjacent to at least a portion of the upper surface to reflect light toward the illumination surface.

3. The device of claim 2, wherein the reflective surface includes a reflective coating disposed over at least a portion of the upper surface.

4. The device of claim 2, wherein the reflective surface includes a prism-like ejection film.

5. The device of claim 2, wherein the reflective surface is separated from the light guide by a material having an index of refraction that is less than an index of refraction of the light guide.

6. The device of claim 1, wherein at least a portion of the upper surface includes a reflective surface.

7. The device of claim 1, wherein the angle α

is greater than 2 degrees and less than 8 degrees.

8. The device of claim 1, further comprising an optical coupler disposed in an optical path between the light source and the light guide entry surface.

9. The device of claim 8, wherein the optical coupler includes a curved reflector.

10. The device of claim 9, wherein the optical coupler includes an etendue preserving reflector.

11. The device of claim 1, wherein the light source includes at least one light emitting diode.

12. The device of claim 11, wherein the light source includes a plurality of light emitting diodes angularly offset from one another about the longitudinal axis.

13. The device of claim 12, wherein the light entry surface is disposed around the longitudinal axis and facing the longitudinal axis, and wherein each light emitting diode includes a light emitting surface that is oriented to provide light through the light entry surface into the light guide in a radial direction relative to the longitudinal axis of the device.

14. The device of claim 1, further comprising an optical conditioner disposed below the illumination surface such that the illumination surface is between the optical conditioner and the upper surface.

15. The device of claim 14, wherein the optical conditioner includes a lenticular film or an array of lenslets.

16. The device of claim 1, wherein the light entry surface is formed by a recess in an upper surface of the light guide.

17. The device of claim 1, wherein the light entry surface has a longitudinal dimension of between 2 mm and 16 mm.

18. The device of claim 17, wherein the light entry surface has a longitudinal dimension of between 2 mm and 6 mm.

19. The device of claim 1, wherein a cross-sectional shape of the light guide taken through the longitudinal axis is one of circular, triangular, rectangular, pentagonal, hexagonal, octagonal, or otherwise polygonal.

20. The device of claim 1, wherein a maximum radial dimension of the light guide is less than or equal to 5 inches.

21. The device of claim 20, wherein the maximum radial dimension of the light guide is less than or equal to 4 inches.

22. The device of claim 21, wherein the maximum radial dimension of the light guide is less than or equal to 2 inches.

23. The device of claim 1, further comprising:

an electrical coupling having at least two separate electrical connections for connecting the illumination device to a power source, and

an electronics chassis disposed between and electrically connecting the electrical coupling and the light source.

24. The device of claim 23, wherein the electronics chassis includes a heat transfer structure thermally coupled to the light source to dissipate heat from the light source.

25. The device of claim 24, wherein the heat transfer structure includes an active heat transfer structure.

26. The device of claim 23, further comprising a heat transfer structure disposed between the electronics chassis and the light guide, the heat transfer structure coupled to the light source to receive heat from the light source, the heat transfer structure including fins to dissipate heat received from the light source.

27. The device of claim 23, wherein the electronics chassis has a maximum radial dimension that is less than a maximum radial dimension of the light guide.

28. A chandelier comprising the device of claim 1.

29. The chandelier of claim 28, further comprising an electrical coupling that is offset on the longitudinal axis from the light source, the light source and the electrical coupling being electrically coupled to one another.

30. The chandelier of claim 29, further comprising a mounting plate disposed between the light source and the electrical coupling, the mounting plate configured to mechanically couple the chandelier to a fixed structure.

31. A method of manufacturing an illumination device, the method comprising:

forming a transparent structure including a tapered upper surface and a lower surface; and

polishing the lower surface of the transparent structure to reduce a longitudinal dimension between the lower surface and the upper surface, wherein a peripheral edge of the transparent structure between the upper surface and the lower surface after polishing defines an angle φ

greater than 1 degree and less than 8 degrees.

32. The method of claim 31, wherein the transparent structure has a maximum radial dimension that is less than or equal to 4 inches.

33. The method of claim 31, wherein forming the transparent structure includes providing a substrate having a surface to support a tapered surface of the transparent structure.

34. The method of claim 31, further comprising forming a light entry surface in a center portion of the transparent structure.

35. The method of claim 34, further comprising positioning a light source near the center portion of the transparent structure.

36. The method of claim 35, wherein positioning the light source near the center portion of the transparent structure includes positioning the light source relative to the transparent structure such that light emitted from the light source is received into the transparent structure through the light entry surface and propagates in a radial direction from the light source toward a periphery of the transparent structure.