SOLID STATE LIGHTING APPARATUS WITH CONFIGURABLE SHUNTS

• US 20110068696A1
• Filed: 09/24/2009
• Published: 03/24/2011
• Est. Priority Date: 09/24/2009
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: van de Ven, Antony P., Negley, Gerald H.
• Granted Patent: US 8,901,829 B2
• Time in Patent Office: Days
• US Class Current: 315/152
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs

Abstract

A solid state lighting apparatus according to some embodiments includes a circuit including a plurality of light emitting devices, and a configurable shunt configured to bypass at least some current around at least one light emitting device of the plurality of light emitting devices. The configurable shunt may include, for example, a tunable resistor, a fuse, a switch, a thermistor, and/or a variable resistor.

Claims

1. A solid state lighting apparatus comprising:

a circuit comprising a plurality of light emitting devices; and

a configurable shunt configured to bypass at least some current around at least one light emitting device of the plurality of light emitting devices.

2. The solid state lighting apparatus of claim 1, wherein the configurable shunt comprises a tunable resistor.

3. The solid state lighting apparatus of claim 1, wherein the configurable shunt comprises a fuse.

4. The solid state lighting apparatus of claim 1, wherein the configurable shunt comprises a switch.

5. The solid state lighting apparatus of claim 1, wherein the configurable shunt comprises a thermistor.

6. The solid state lighting apparatus of claim 1, wherein the configurable shunt comprises a variable resistor.

7. The solid state lighting apparatus of claim 1, wherein the solid state light emitting devices are connected in series to form a string including an anode terminal at a first end of the string and a cathode terminal at a second end of the string;

and

wherein the configurable shunt is coupled between a contact of one of the solid state light emitting devices and the cathode or anode terminal of the string.

8. The solid state lighting apparatus of claim 7, wherein each of the solid state lighting devices includes an anode contact and a cathode contact, the anode contact of each of the solid state light emitting devices is coupled to the cathode contact of an adjacent solid state light emitting device in the string or to the anode terminal of the string, and the cathode contact of each of the solid state light emitting devices is coupled to the anode contact of an adjacent solid state light emitting device in the string or to the cathode terminal of the string.

9. The solid state lighting apparatus of claim 8, wherein the switch comprises an electrically controllable switch, the solid state lighting apparatus further comprising a control circuit coupled to the switch and configured to electrically control an ON/OFF state of the switch.

10. The solid state lighting apparatus of claim 9, further comprising an interface coupled to the control circuit and configured to receive an external input and responsively provide a switch command to the control circuit, wherein the control circuit is configured to control the ON/OFF state of the switch in response to the switch command.

11. The solid state lighting apparatus of claim 7, further comprising a plurality of configurable shunts coupled between contacts of respective ones of the solid state light emitting devices and the cathode or anode terminal of the string.

12. The solid state lighting apparatus of claim 11, wherein the solid state light emitting devices comprise respective groups of series-connected solid state light emitting devices, wherein the groups of series-connected solid state light emitting devices are connected in series between the anode contact of the string and the cathode contact of the string, and wherein the configurable shunts are coupled between respective groups of series-connected solid state light emitting devices and the cathode or anode terminal of the string.

13. The solid state lighting apparatus of claim 12, wherein at least two groups of solid state light emitting devices comprise different numbers of solid state light emitting devices.

14. The solid state lighting apparatus of claim 13, wherein a first group of solid state light emitting devices is coupled directly to the cathode terminal of the string and includes a first number of solid state light emitting devices, and wherein a second group of solid state light emitting devices is not coupled directly to the cathode terminal of the string and includes a second number of solid state light emitting devices, wherein the first number is not equal to the second number.

15. The solid state lighting apparatus of claim 14, wherein the first number is less than the second number.

16. The solid state lighting apparatus of claim 14, wherein the first number is greater than the second number.

17. The solid state lighting apparatus of claim 7, further comprising a thermistor coupled in series with the string.

18. The solid state lighting apparatus of claim 7, further comprising a variable resistor coupled in series with the string.

19. The solid state lighting apparatus of claim 7, wherein the string comprises a first string of light emitting diodes configured to emit light having a first chromaticity, the apparatus further comprising a second string of light emitting devices configured to emit light having a second chromaticity, different from the first chromaticity.

20. The solid state lighting apparatus of claim 19, wherein the first chromaticity and the second chromaticity are non-white, and wherein light emitted by both the first and second strings has a combined chromaticity that is white.

21. The solid state lighting apparatus of claim 19, wherein the second string of light emitting devices comprises a second configurable shunt configured to bypass at least some current in the second string around at least one light emitting device in the second string.

22. The solid state lighting apparatus of claim 1, wherein at least two of the light emitting devices are connected in parallel, and the configurable shunt is configured to bypass current around the at least two parallel connected light emitting devices.

23. A method of operating a solid state lighting apparatus including a string of series-connected solid state light emitting devices, the string including an anode terminal at a first end of the string and a cathode terminal at a second end of the string, the method comprising:

passing a reference current through the string;

measuring color and/or intensity of light output from the string in response to the reference current; and

providing at least one configurable shunt coupled between a contact of one of the solid state light emitting devices and the anode or cathode terminal of the string in response to the measured color and/or intensity of light output from the string, wherein the configurable shunt electrically bypasses the one of the solid state light emitting devices when a voltage is applied across the anode and cathode terminals of the string.

24. The method of claim 23, wherein the string comprises a first string of solid state light emitting devices configured to emit light having a dominant wavelength in a first portion of the visible spectrum, and wherein the solid state lighting apparatus further comprises a second string of solid state light emitting devices configured to emit light having a dominant wavelength in a second portion of the visible spectrum, different from the first portion, the method further comprising:

passing a second reference current through the second string, wherein measuring color and/or intensity of light output comprises measuring color and/or intensity of light output from the first string and the second string in response to the reference current and the second reference current.

25. The method of claim 23, wherein providing the configurable shunt comprises activating a switch coupled between the contact of the one of the solid state light emitting devices and the anode or cathode terminal of the string.

26. The method of claim 23, wherein providing the configurable shunt comprises varying a resistance of a tunable resistor coupled between the contact of the one of the solid state light emitting devices and the anode or cathode terminal of the string.

27. A solid state lighting apparatus comprising:

a circuit comprising a plurality of light emitting devices; and

means for bypassing at least some current around at least one light emitting device of the plurality of light emitting devices.

28. The solid state lighting apparatus of claim 27, wherein the means for bypassing at least some current around at least one light emitting device of the plurality of light emitting devices comprises a configurable shunt.

29. The solid state lighting apparatus of claim 27, wherein the means for bypassing at least some current around at least one light emitting device of the plurality of light emitting devices comprises a plurality of configurable shunts.