Illumination apparatus confining light by total internal reflection and methods of forming the same

• US 8,591,072 B2
• Filed: 02/17/2012
• Issued: 11/26/2013
• Est. Priority Date: 11/16/2011
• Status: Active Grant

• Current Assignee: Oree Advanced Illumination Solutions Ltd.
• Original Assignee: Oree, Inc.
• Inventors: Shani, Yosi, Fine, Eran, Schiffmann, Baruch, Arbiv, Dafna Bortman, Badihi, Avner
• Primary Examiner(s): Green, Tracie Y
• Application Number:
  US13/398,951
• Publication Number:
  US 20130121001A1
• Time in Patent Office: 648 Days
• Field of Search: 313500-512, 313581-587, 362/84, 362/97.1, 362/611, 362/97.2, 362/97.3, 385/129, 385/39
• US Class Current: 362/296.01
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0025 Diffusing sheet or layer; Prismatic sheet or layer
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/0083 Details of electrical connections of light sources to drivers, circuit boards, or the like
• CPC Class Codes: G02B 6/009 of the light source in the package G02B6/0021 takes precedence
• CPC Class Codes: G02B 6/0091 of the light source relative to the light guide G02B6/0021 takes precedence
• 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 33/483 Containers
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

In various embodiments, an illumination apparatus includes an air gap between a sub-assembly and a waveguide attached thereto at a plurality of discrete attachment points, as well as a bare-die light-emitting diode encapsulated by the waveguide.

Claims

1. An illumination device comprising:

a waveguide;

a sub-assembly attached to a first surface of the waveguide only at a plurality of discrete attachment points, an air gap separating the first surface of the waveguide and the sub-assembly between the plurality of discrete attachment points; and

a bare-die light-emitting diode (LED) mechanically coupled to the sub-assembly and disposed within the waveguide, light emitted by the bare-die LED being in-coupled into the waveguide.

2. The illumination device of claim 1, further comprising a spacer mechanically coupling the bare-die LED to the sub-assembly and raising the bare-die LED above a top surface of the sub-assembly.

3. The illumination device of claim 1, wherein the waveguide comprises, opposite the first surface, a second surface for emitting light emitted by the bare-die LED and propagating within the waveguide.

4. The illumination device of claim 3, wherein the first and second surfaces are substantially planar.

5. The illumination device of claim 1, wherein the waveguide comprises, adjoining and not parallel to the first surface, a second surface for emitting light emitted by the bare-die LED and propagating within the waveguide.

6. The illumination device of claim 5, wherein the first and second surfaces are substantially perpendicular to each other.

7. The illumination device of claim 1, further comprising, disposed in the waveguide above the bare-die LED, an in-coupling element for converting light emitted by the bare-die LED from an unconfined mode to a confined mode.

8. The illumination device of claim 7, wherein the in-coupling element comprises at least one of a reflector, a prism, or one or more scattering elements.

9. The illumination device of claim 1, further comprising, disposed over a second surface of the waveguide opposite the first surface, a substantially opaque absorber for blocking the propagation of light therethrough.

10. The illumination device of claim 9, wherein the absorber is attached to the second surface of the waveguide only at a second plurality of discrete attachment points, an air gap being disposed between the second surface of the waveguide and the absorber between the second plurality of discrete attachment points.

11. The illumination device of claim 1, further comprising an adhesive material disposed at each of the plurality of discrete attachment points.

12. The illumination device of claim 11, wherein the adhesive is flexible.

13. The illumination device of claim 1, wherein the waveguide defines a plurality of protrusions from the first surface, each of the protrusions being disposed at one of the discrete attachment points, a maximum height of the protrusions above the first surface being approximately equal to a thickness of the air gap.

14. The illumination device of claim 1, further comprising a plurality of discrete separators disposed between the first surface and the sub-assembly, each of the separators being disposed at one of the discrete attachment points, a thickness of the separators being approximately equal to a thickness of the air gap.

15. The illumination device of claim 14, wherein each separator is attached to the first surface and to the sub-assembly with an adhesive material.

16. The illumination device of claim 1, wherein at least one discrete attachment point is disposed on a relief defined by at least one relief trench extending through a thickness of the sub-assembly, the relief being elastically deformable in at least a first direction substantially perpendicular to the first surface.

17. The illumination device of claim 16, wherein the relief is elastically deformable in a second direction substantially perpendicular to the first direction.

18. The illumination device of claim 16, wherein at least one discrete attachment point is not disposed on a relief and thereby is not elastically deformable.

19. The illumination device of claim 1, wherein the plurality of discrete attachment points are disposed in a line substantially perpendicular to a propagation direction extending from the bare-die LED to an output region of the waveguide.

20. The illumination device of claim 1, wherein the waveguide defines a recess in the first surface, and the bare-die LED is disposed within the recess,

further comprising at least one index-matching material filling at least a portion of the recess and encapsulating the bare-die LED, thereby facilitating in-coupling of light emitted by the bare-die LED into the waveguide.

21. The illumination device of claim 20, wherein a free surface of at least one said index-matching material in the recess is spaced away from the sub-assembly, thereby defining a second air gap between the sub-assembly and the free surface.

22. The illumination device of claim 21, wherein the free surface of the at least one index-matching material is substantially parallel to the first surface of the waveguide.

23. The illumination device of claim 20, wherein, in a propagation direction extending from the bare-die LED to an output region of the waveguide, a dimension of the recess is no more than three times a dimension of the bare-die LED in the propagation direction.

24. The illumination device of claim 23, wherein the dimension of the recess in the propagation direction is no more than two times the dimension of the bare-die LED in the propagation direction.

25. The illumination device of claim 24, wherein the dimension of the recess in the propagation direction is approximately equal to the dimension of the bare-die LED in the propagation direction.

26. A method of forming an illumination device incorporating a bare-die light-emitting diode (LED) mechanically coupled to a sub-assembly, the method comprising:

attaching the sub-assembly to a first surface of a waveguide at only a plurality of discrete attachment points, thereby defining an air gap disposed between the first surface of the waveguide and the sub-assembly between the plurality of discrete attachment points; and

encapsulating the bare-die LED within a recess defined by the waveguide in the first surface, thereby facilitating in-coupling of light emitted by the bare-die LED into the waveguide.

27. The method of claim 26, wherein encapsulating the bare-die LED comprises at least partially surrounding the bare-die LED with at least one index-matching material.

28. The method of claim 27, wherein at least one said index-matching material is disposed within the recess before the sub-assembly is attached to the first surface of the waveguide.

29. The method of claim 26, wherein encapsulating the bare-die LED comprises:

at least partially surrounding the bare-die LED with a first index-matching material prior to attachment of the sub-assembly to the first surface of the waveguide;

disposing a second index-matching material within the recess prior to attachment of the sub-assembly to the first surface of the waveguide; and

at least partially surrounding the bare-die LED and a portion of the first index-matching material with the second index-matching material during attachment of the sub-assembly to the first surface of the waveguide.

30. The method of claim 26, wherein at least one discrete attachment point is disposed on a relief defined by at least one relief trench extending through a thickness of the sub-assembly, the relief being elastically deformable in at least a first direction substantially perpendicular to the first surface.

31. The method of claim 30, wherein at least one discrete attachment point is not disposed on a relief and thereby is not elastically deformable.

32. The method of claim 26, wherein attaching the sub-assembly to the first surface of the waveguide comprises forming the plurality of discrete attachment points via dispersal of an adhesive between the sub-assembly and the waveguide at each of the discrete attachment points.

33. A method of forming an illumination device incorporating a bare-die light-emitting diode (LED), the method comprising encapsulating the bare-die LED within a waveguide by disposing the bare-die LED within a waveguide material such that the waveguide material directly contacts, without a gap therebetween, the bare-die LED or an index-matching material disposed around and in direct contact with the bare-die LED.

34. The method of claim 33, further comprising attaching a sub-assembly to a first surface of the waveguide at only a plurality of discrete attachment points, thereby defining an air gap disposed between the first surface of the waveguide and the sub-assembly between the plurality of discrete attachment points.

35. The method of claim 34, wherein the waveguide defines a plurality of protrusions from the first surface, each of the protrusions being disposed at one of the discrete attachment points, a maximum height of the protrusions above the first surface being approximately equal to a thickness of the air gap.

36. The method of claim 34, wherein, substantially simultaneously, (i) the waveguide and the sub-assembly are brought into contact at the plurality of discrete attachment points, and (ii) the bare-die LED is encapsulated within the waveguide.

37. The method of claim 33, wherein at least one discrete attachment point is disposed on a relief defined by at least one relief trench extending through a thickness of the sub-assembly, the relief being elastically deformable in at least a first direction substantially perpendicular to the first surface.

38. The method of claim 37, wherein at least one discrete attachment point is not disposed on a relief and thereby is not elastically deformable.

39. The method of claim 33, wherein the bare-die LED is encapsulated substantially simultaneously with formation of the waveguide.

40. The method of claim 33, further comprising disposing the index-matching material around the bare-die LED prior to encapsulating the bare-die LED within the waveguide.