Failure mitigation in arrays of light-emitting devices

• US 8,653,539 B2
• Filed: 07/15/2011
• Issued: 02/18/2014
• Est. Priority Date: 01/04/2010
• Status: Active Grant

• Current Assignee: Cooledge Lighting Inc.
• Original Assignee: Cooledge Lighting Inc.
• Inventors: Tischler, Michael, Schick, Philippe, Sheen, Calvin Wade, Jungwirth, Paul
• Primary Examiner(s): PHILOGENE, HAISSA
• Application Number:
  US13/183,684
• Publication Number:
  US 20110316422A1
• Time in Patent Office: 949 Days
• Field of Search: 257/11, 257/79, 257/81, 257/99, 257/88, 257/82, 315/169.1, 315/169.3, 315/122, 315/127, 315/307, 315/312, 315/291, 315/185.R, 315/192, 315/193, 315/185.S
• US Class Current: 257/81
• CPC Class Codes: F21K 9/20 Light sources comprising attachment means
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: H05B 45/54 in a series array of LEDs
• CPC Class Codes: H05K 2201/09263 Meander
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/10174 Diode
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

In accordance with certain embodiments, an illumination system comprising a plurality of power strings features elements facilitating compensation for failure of one or more light-emitting elements connected along each power string.

Claims

1. An illumination system comprising:

a plurality of power strings connectable to a power source, each power string comprising;

a power conductor;

along each power conductor, a plurality of contact pairs interrupting and spaced apart along the power conductor, the contacts within a pair being insulatively spaced apart and electrically bridged by a light-emitting element so that the light-emitting elements are connected along the power conductor; and

at least at one contact pair, an element facilitating compensation for failure of the associated light-emitting element.

2. The system of claim 1, wherein at least one light-emitting element comprises a light-emitting diode.

3. The system of claim 1, wherein at least one light-emitting element comprises an unpackaged light-emitting diode.

4. The system of claim 1, wherein the light-emitting elements are electrically connected in series along the power conductor.

5. The system of claim 1, wherein the element is an additional area on each of the contacts of the contact pair, the additional area extending beyond the associated light-emitting element and being bridgeable by a replacement light-emitting element or a shorting member.

6. The system of claim 5, wherein the associated light-emitting element is non-centered on the bridged contacts.

7. The system of claim 1, wherein the element is an additional associated light-emitting element.

8. The system of claim 7, wherein the associated light-emitting element and the additional associated light-emitting element are both on a single die.

9. The system of claim 7, wherein the associated light-emitting element and the additional associated light-emitting element are on separate dies, the associated light-emitting element being adjacent to the additional associated light-emitting element and also electrically bridging the contacts.

10. The system of claim 9, further comprising a power source providing a current level sufficient to drive two or more light-emitting elements across each contact pair but sufficiently small to avoid damage to an undamaged light-emitting element in the event of damage to the associated light-emitting element or the additional associated light-emitting element.

11. The system of claim 1, wherein the element is an open-circuit-detection element adjacent to the associated light-emitting element and bridging the contacts, the open-circuit-detection element being configured to sense whether the associated light-emitting element is open and, if so, to short-circuit the contacts.

12. The system of claim 1, further comprising a plurality of shorting members cross-connecting at least one of the power strings with at least one other power string.

13. The system of claim 1, wherein at least one light-emitting element is at least one of mechanically or electrically connected to the contacts of a contact pair by an adhesive.

14. The system of claim 13, wherein the adhesive comprises a conductive adhesive.

15. The system of claim 14, wherein the adhesive comprises an anisotropically conductive adhesive.

16. The system of claim 1, wherein at least one light-emitting element is at least one of mechanically or electrically connected to the contacts of a contact pair by solder.

17. The system of claim 1, further comprising a flexible substrate on which the plurality of power strings is disposed.

18. The system of claim 1, wherein the element comprises a zener diode.

19. The system of claim 18, wherein a zener voltage of the zener diode is higher than a forward voltage sufficient to operate the associated light-emitting element.

20. The system of claim 1, further comprising:

a controller for detecting a power string failure and activating a reserved power string located proximately to the failed power string.

21. The system of claim 1, wherein at least one light-emitting element comprises a phosphorescent material for converting at least a portion of light emitted by the light-emitting element from one set of wavelengths to another.

22. An illumination system comprising:

a plurality of power strings connectable to a power source, each power string comprising a power conductor;

along each power conductor, a plurality of contact pairs interrupting and spaced apart along the power conductor, the contacts within a pair being insulatively spaced apart and electrically bridged by a light-emitting element so that the light-emitting elements are connected along the power conductor,

wherein the light-emitting elements occupy points on a pattern and the power strings follow nonlinear paths through the pattern, such that the light-emitting elements along each power string are not linearly disposed within the pattern.

23. The system of claim 22, wherein at least one light-emitting element comprises a phosphorescent material for converting at least a portion of light emitted by the light-emitting element from one set of wavelengths to another.

24. The system of claim 22, wherein at least one light-emitting element comprises a light-emitting diode.

25. The system of claim 22, wherein at least one light-emitting element comprises an unpackaged light-emitting diode.

26. The system of claim 22, wherein the light-emitting elements are electrically connected in series along the power conductor.

27. The system of claim 22, wherein the pattern is a rectilinear grid.

28. The system of claim 22, wherein at least one light-emitting element is at least one of mechanically or electrically connected to the contacts of a contact pair by an adhesive.

29. The system of claim 28, wherein the adhesive comprises a conductive adhesive.

30. The system of claim 29, wherein the adhesive comprises an anisotropically conductive adhesive.

31. The system of claim 22, wherein at least one light-emitting element is at least one of mechanically or electrically connected to the contacts of a contact pair by solder.

32. The system of claim 22, wherein the pattern is a hexagonal grid.

33. The system of claim 22, further comprising a flexible substrate on which the plurality of power strings is disposed.

34. The system of claim 22, further comprising a plurality of shorting members cross-connecting at least one of the power strings with at least one other power string.

35. The system of claim 22, further comprising a controller for detecting a power string failure and activating a reserved power string located proximately to the failed power string.

36. The system of claim 22, wherein the pattern is three-dimensional.

37. The system of claim 22, further comprising, disposed over the plurality of power strings, at least one of a homogenizing optic or a diffuser.