Failure mitigation in arrays of light-emitting devices
View Patent ↗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.
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.