APPARATUS AND METHOD FOR BYPASSING FAILED LEDS IN LIGHTING ARRAYS

• US 20110006689A1
• Filed: 06/17/2010
• Published: 01/13/2011
• Est. Priority Date: 06/18/2009
• Status: Active Grant

• Current Assignee: Musco Corporation
• Original Assignee: Musco Corporation
• Inventors: Blanchard, David L., Gordin, Myron
• Granted Patent: US 8,531,115 B2
• Time in Patent Office: Days
• US Class Current: 315/121
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/54 in a series array of LEDs

Abstract

An apparatus, method and system for controlling one or multiple lighting sources such as those powered by driver circuits or voltage splitting methods, to provide an alternative current path around a failed lighting source when one or more individual lighting sources fail.

Claims

1. A method for controlling multiple light sources operatively connected in series, such as those powered by a driver circuit, by providing an alternative current path around at least one of the multiple light sources when one light source fails comprising:

(a) automatically sensing a condition indicative of a failure of a light source of the multiple light sources;

(b) automatically providing an alternative current path around the at least one light sources by;

(b1) allowing significantly less than operating current through the alternative current path until the condition indicative of a failure of a lighting source;

(b2) triggering substantially all operating current to pass through the alternative current path;

(c) to allow operating current to bypass the light source sensed to have failed so it is available for other light sources.

2. The method of claim 1 further comprising passing essentially 100% of the operating current around the failed lighting source.

3. The method of claim 1 wherein the multiple light sources comprise a substring of light sources and the other light sources are in operative electrical connection with the substring of multiple light sources.

4. The method of claim 1 further comprising adjusting or trimming voltage and/or current so that operating voltage and current to the other light sources can be maintained when a single light source open failure occurs.

5. The method of claim 1 further comprising detecting an open failure by monitoring voltage relative to a pre-set triggering voltage.

6. The method of claim 1 wherein the alternative current pathway is not activated on a short circuit of a single light source.

7. The method of claim 1 wherein the alternative current pathway is operated until power drops below a certain level or is removed from the circuit.

8. The method of claim 1 wherein the light source comprises an LED or other solid state source.

9. The method of claim 1 wherein the bypass occurs at a predesigned triggering voltage and the alternative current path is latched to active for any of the following conditions;

(a) the sensed failure occurs while operating power is through the multiple light sources;

or

(b) the failure occurs before operating power is applied to the multiple light sources.

10. An apparatus for controlling multiple light sources such as those powered by a driver circuit, to provide alternative failure mode when one or more individual light source fails, comprising:

(a) an alternative current path circuit in parallel with a subset of the multiple lighting sources;

(b) the alternate circuit path current being significantly less than the single lighting source current such that when the single light source open failure occurs, the alternative circuit detects the same and passes on the order of 100% of the single lighting source current to maintain current to the other lighting sources.

11. The apparatus claim 10 further comprising producing a voltage drop that is less than the light source operating voltage.

12. The apparatus claim 10 further comprising a component to adjust or trim operating voltage and/or current that can be maintained when a light source open failure occurs.

13. The apparatus claim 10 wherein the circuit is electronic or primarily electronic.

14. The apparatus claim 10 wherein the light source comprises an LED or other solid state lighting source.

15. The apparatus claim 10 wherein the circuit comprises a zener diode, a PNP transistor and an NMOS FET, a PNP transistor and an NPN transistor, an SCR, or a transistorized circuit.

16. A method for operating a solid state light source comprising:

a. providing an alternate current path around the solid state light source;

b. holding the alternative current path inactive so long as a condition indicative of an open solid state light source failure is not sensed;

c. activating the alternate current path upon detecting a condition indicative of an open solid state light source failure.

17. The method of claim 16 further comprising providing the alternative current path around a plurality of solid state light sources and activating the alternative current path upon detecting a condition indicative of an open solid state light failure of any of the plurality of solid state light sources.

18. The method of claim 17 further comprising operatively connecting the plurality of LEDs with other LEDs.

19. An LED lighting apparatus comprising:

a. a string of a plurality of LED light sources connected in series;

b. an alternative current path circuit placed in parallel with the string of LEDs;

c. the alternative current path circuit including a transistor circuit wherein

i. the transistor circuit is substantially inactive except for conducting small leakage and bias currents when the string of LEDs is fully operational;

ii. the transistor circuit becomes automatically active to pass at least substantially most of the operating current if sufficient voltage indicative of an open LED failure triggers the transistor.

20. The apparatus of claim 19 wherein the transistor circuit comprises a zener diode, resistors, capacitors, and two transistors, wherein the capacitors filter transients to prevent false triggering of the transistors.

21. The apparatus of claim 20 wherein the transistor circuit in the inactive state functions to present much less than forward voltage to prevent the transistors from conducting, but presents much greater than the forward voltage when triggered by a condition indicative of an open LED failure.

22. A method of designing an alternative current path circuit adapted for placement in parallel with an LED or string of LEDs to be essentially inactive until a condition indicative of an open LED failure is sensed, and then automatically becoming active to bypass that LED or the string of LEDs including that LED, with substantially all the operating current, the method comprising:

determining and setting a triggering voltage for automatic triggering of an active state for the circuit.