Time division modulation with average current regulation for independent control of arrays of light emitting diodes

• US 7,902,771 B2
• Filed: 11/21/2006
• Issued: 03/08/2011
• Est. Priority Date: 11/21/2006
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Exclara, Inc. (Million Star Technology Ltd.)
• Inventors: Rodriguez, Harry, Shteynberg, Anatoly
• Primary Examiner(s): Vu; David Hung
• Application Number:
  US11/603,689
• Publication Number:
  US 20080116818A1
• Time in Patent Office: 1,568 Days
• Field of Search: 315/291, 315/185.R, 315/186, 315/187, 315/193, 315/191, 315/294, 315/295, 315/307, 315/308
• US Class Current: 315/307
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Exemplary apparatus, method and system embodiments provide for separately and independently sourcing current to a series of light emitting diodes of a plurality of series of light-emitting diodes. An exemplary apparatus comprises a power converter which generates a current, a first multiplexer, and a controller. The controller provides for sequential and separate switching of the current through the first multiplexer to each of the series of light-emitting diodes for a corresponding period of time. An average current provided by the power converter is determined as substantially equal to a sum of the corresponding currents through the plurality of series of light-emitting diodes. A total period for switching current to all of the series of light-emitting diodes is also determined. A corresponding time period for switching current to a selected corresponding series of light-emitting diodes is substantially equal to a proportion of the total period determined as a ratio of the corresponding current for the selected corresponding series of light-emitting diodes to the average current provided by the power converter.

Claims

1. An apparatus for providing current independently to a series of light emitting diodes of a plurality of series of light-emitting diodes, the apparatus comprising:

a power converter couplable to the plurality of series of light-emitting diodes, the power converter to generate a current, the power converter further comprising a first current sensor;

a first multiplexer couplable to each series of light-emitting diodes of the plurality of series of light-emitting diodes;

a memory to store a plurality of parameters corresponding to the plurality of series of light-emitting diodes; and

a controller coupled to the power converter, to the memory and to the first multiplexer, the controller to provide for sequential and separate switching of the current through the first multiplexer to each of the series of light-emitting diodes, of the plurality of series of light-emitting diodes, for a corresponding period of time, the controller further to determine a peak input current through the first current sensor and to predict an output voltage across a selected series of light-emitting diodes using the plurality of parameters stored in memory.

2. The apparatus of claim 1, wherein the controller further is to provide for no switching of current through the first multiplexer to all remaining series of light-emitting diodes while current is switched to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes.

3. The apparatus of claim 1, wherein the controller further is to determine an average current provided by the power converter as about equal to a sum of a plurality of corresponding currents through the plurality of series of light-emitting diodes.

4. The apparatus of claim 3, wherein the controller further is to determine a total period for switching current to all of the series of light-emitting diodes of the plurality of series of light-emitting diodes.

5. The apparatus of claim 4, wherein the controller further is to determine a corresponding time period for switching current to a selected corresponding series of light-emitting diodes as substantially equal to a proportion of the total period determined as a ratio of the corresponding current for the selected corresponding series of light-emitting diodes to the average current provided by the power converter.

6. The apparatus of claim 1, wherein the memory stores the plurality of parameters as a look up table.

7. The apparatus of claim 6, wherein the controller further is to revise the predicted output voltage based upon a measured output voltage across a selected series of light-emitting diodes.

8. The apparatus of claim 1, wherein the power converter further comprises an input voltage divider, and wherein the controller further is to determine an input voltage across the input voltage divider.

9. The apparatus of claim 1, further comprising:

at least one second current sensor in series with at least one of the series of light-emitting diodes, of the plurality of series of light-emitting diodes, and

wherein the controller further is to determine an output current through the second current sensor.

10. The apparatus of claim 1, further comprising:

a plurality of output voltage dividers, each output voltage divider couplable in parallel to a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes,

wherein the controller further is to determine a corresponding output voltage across the corresponding output voltage divider of the plurality of output voltage dividers.

11. The apparatus of claim 10, further comprising:

a second, voltage sensor multiplexer coupled to the plurality of output voltage dividers and the controller,

wherein the controller further is to control switching of the second multiplexer to a selected output voltage divider of the plurality of output voltage dividers.

12. The apparatus of claim 1, further comprising:

a second, current sensor multiplexer couplable to the plurality of series of light-emitting diodes and coupled to the controller,

wherein the controller further is to control switching of the second multiplexer to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes for measuring a corresponding current through the selected series of light-emitting diodes.

13. The apparatus of claim 12, wherein the controller further is to determine the corresponding period of time for switching of current to a selected series of light-emitting diodes based on a comparison of a measured corresponding current to a predetermined current level for the selected series of light-emitting diodes.

14. The apparatus of claim 1, wherein the first multiplexer further comprises:

a plurality of switches, each switch of the plurality of switches correspondingly coupled to a first, high side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

15. The apparatus of claim 1, wherein the first multiplexer further comprises:

a plurality of switches, each switch of the plurality of switches correspondingly coupled to a second, low side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

16. The apparatus of claim 1, wherein the first multiplexer further comprises:

a plurality of first switches, each switch of the plurality of first switches correspondingly coupled to a first, high side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes; and

a plurality of second switches, each switch of the plurality of second switches correspondingly coupled to a second, low side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

17. The apparatus of claim 1, further comprising:

a plurality of capacitors, each capacitor of the plurality of capacitors coupled in parallel to a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

18. The apparatus of claim 17, wherein the first multiplexer further comprises:

a plurality of first switches, each switch of the plurality of first switches correspondingly coupled to a first, high side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes; and

a second switch coupled to the plurality of capacitors.

19. The apparatus of claim 1, wherein the controller further is to determine the corresponding period of time for switching of current to a selected series of light-emitting diodes based on an integer multiple of a period of switching of the power converter.

20. The apparatus of claim 1, wherein the controller further is to control switching of the first multiplexer to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes when current through the power converter is substantially zero.

21. The apparatus of claim 1, wherein the controller further is, in response to a first input, to adjust an output brightness of the plurality of series of light-emitting diodes by modifying each corresponding period of time of current switching to each of the series of light-emitting diodes.

22. The apparatus of claim 1, wherein the controller further is, in response to a second input, to adjust an output color of the plurality of series of light-emitting diodes by modifying at least one corresponding period of time of current switching to at least one of the series of light-emitting diodes of the plurality of series of light-emitting diodes.

23. A lighting system, comprising:

a plurality of series of light-emitting diodes;

a power converter coupled to the plurality of series of light-emitting diodes, the power converter to generate a current, the power converter further comprising a first current sensor;

a first multiplexer coupled to each series of light-emitting diodes of the plurality of series of light-emitting diodes;

a memory to store a plurality of parameters corresponding to the plurality of series of light-emitting diodes; and

a controller coupled to the power converter, to the memory and to the first multiplexer, the controller to provide for sequential and separate switching of the current through the first multiplexer to each of the series of light-emitting diodes, of the plurality of series of light-emitting diodes, for a corresponding period of time, the controller further to determine a peak input current through the first current sensor and to predict an output voltage across a selected series of light-emitting diodes using the plurality of parameters stored in memory.

24. The system of claim 23, wherein the controller further is to provide for no switching of current through the first multiplexer to all remaining series of light-emitting diodes while current is switched to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes.

25. The system of claim 23, wherein the controller further is to determine an average current provided by the power converter as substantially equal to a sum of a plurality of corresponding currents through the plurality of series of light-emitting diodes.

26. The system of claim 25, wherein the controller further is to determine a total period for switching current to all of the series of light-emitting diodes of the plurality of series of light-emitting diodes.

27. The system of claim 26, wherein the controller further is to determine a corresponding time period for switching current to a selected corresponding series of light-emitting diodes as substantially equal to a proportion of the total period determined as a ratio of the corresponding current for the selected corresponding series of light-emitting diodes to the average current provided by the power converter.

28. The system of claim 23, wherein the memory stores the plurality of parameters as a look up table.

29. The system of claim 28, wherein the controller further is to revise the predicted output voltage based upon a measured output voltage across a selected series of light-emitting diodes.

30. The system of claim 23, wherein the power converter further comprises an input voltage divider, and wherein the controller further is to determine an input voltage across the input voltage divider.

31. The system of claim 23, further comprising:

at least one second current sensor in series with at least one of the series of light-emitting diodes, of the plurality of series of light-emitting diodes,

wherein the controller further is to determine and output current through the second current sensor.

32. The system of claim 23, further comprising:

a plurality of output voltage dividers, each output voltage divider coupled in parallel to a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes,

wherein the controller further is to determine a corresponding output voltage across the corresponding output voltage divider of the plurality of output voltage dividers.

33. The system of claim 32, further comprising:

a second, voltage sensor multiplexer coupled to the plurality of second voltage dividers and the controller,

wherein the controller further is to control switching of the second multiplexer to a selected second voltage divider of the plurality of second voltage dividers.

34. The system of claim 23, further comprising:

a second, current sensor multiplexer coupled to the plurality of series of light-emitting diodes and to the controller, and

wherein the controller further is to control switching of the second multiplexer to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes for measuring a corresponding current through the selected series of light-emitting diodes.

35. The system of claim 34, wherein the controller further is to determine the corresponding period of time for switching of current to a selected series of light-emitting diodes based on a comparison of a measured corresponding current to a predetermined current level for the selected series of light-emitting diodes.

36. The system of claim 23, wherein the first multiplexer further comprises:

a plurality of switches, each switch of the plurality of switches correspondingly coupled to a first, high side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

37. The system of claim 23, wherein the first multiplexer further comprises:

a plurality of switches, each switch of the plurality of switches correspondingly coupled to a second, low side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

38. The system of claim 23, wherein the first multiplexer further comprises:

a plurality of first switches, each switch of the plurality of first switches correspondingly coupled to a first, high side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes; and

a plurality of second switches, each switch of the plurality of second switches correspondingly coupled to a second, low side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

39. The system of claim 23, further comprising:

a plurality of capacitors, each capacitor of the plurality of capacitors coupled in parallel to a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes.

40. The apparatus of claim 39, wherein the first multiplexer further comprises:

a plurality of first switches, each switch of the plurality of first switches correspondingly coupled to a first, high side of a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes; and

a second switch coupled to the plurality of capacitors.

41. The system of claim 23, wherein the controller further is to determine the corresponding period of time for switching of current to a selected series of light-emitting diodes based on an integer multiple of a period of switching of the power converter.

42. The system of claim 23, wherein the controller further is to control switching of the first multiplexer to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes when current through the power converter is substantially zero.

43. The system of claim 23, wherein the controller further is, in response to a first input, to adjust an output brightness of the plurality of series of light-emitting diodes by modifying each corresponding period of time of current switching to each of the series of light-emitting diodes.

44. The system of claim 23, wherein the controller further is, in response to a second input, to adjust an output color of the plurality of series of light-emitting diodes by modifying at least one corresponding period of time of current switching to at least one of the series of light-emitting diodes of the plurality of series of light-emitting diodes.

45. An apparatus for providing current independently to a series of light emitting diodes of a plurality of series of light-emitting diodes, the apparatus comprising:

a power converter couplable to the plurality of series of light-emitting diodes, the power converter to generate a current, the power converter further comprising a first current sensor;

a first multiplexer couplable to each series of light-emitting diodes of the plurality of series of light-emitting diodes;

a memory to store, as a look up table, a plurality of parameters corresponding to the plurality of series of light-emitting diodes; and

a controller coupled to the power converter, to the first multiplexer and to the memory, the controller to provide for sequential and separate switching of the current through the first multiplexer to each of the series of light-emitting diodes, of the plurality of series of light-emitting diodes, for a corresponding period of time;

the controller further to determine a peak input current through the first current sensor, to determine an average current provided by the power converter as a substantially equal to sum of a plurality of corresponding currents through the plurality of series of light-emitting diodes, to determine a total period for switching current to all of the series of light-emitting diodes of the plurality of series of light-emitting diodes, to determine a corresponding time period for switching current to a selected corresponding series of light-emitting diodes as substantially equal to a proportion of the total period determined as a ratio of the corresponding current for the selected corresponding series of light-emitting diodes to the average current provided by the power converter, and the controller further to predict an output voltage across a selected series of light-emitting diodes using the plurality of parameters stored in memory.

46. The apparatus of claim 45, wherein the controller further is to revise the predicted output voltage based upon a measured output voltage across a selected series of light-emitting diodes.

47. The apparatus of claim 45, further comprising:

a plurality of voltage dividers, each voltage divider coupled in parallel to a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes; and

a second multiplexer coupled to the plurality of voltage dividers and the controller;

wherein the controller further is to control switching of the second multiplexer to a selected voltage divider of the plurality of voltage dividers and to determine a corresponding output voltage across the corresponding voltage divider of the plurality of voltage dividers.

48. The apparatus of claim 45, further comprising:

a plurality of second current sensors, each second current sensor coupled in series with a corresponding series of light-emitting diodes of the plurality of series of light-emitting diodes; and

a second multiplexer coupled to the plurality of series of light-emitting diodes, to the plurality of second current sensors, and to the controller;

wherein the controller further is to control switching of the second multiplexer to a selected series of light-emitting diodes of the plurality of series of light-emitting diodes for measuring a corresponding current through the selected series of light-emitting diodes.

49. The apparatus of claim 45, wherein the controller further is to determine the corresponding period of time for switching of current to a selected series of light-emitting diodes based on a comparison of a measured corresponding current to a predetermined current level for the selected series of light-emitting diodes.

50. The apparatus of claim 45, wherein the controller further is to determine the corresponding period of time for switching of current to a selected series of light-emitting diodes based on an integer multiple of a period of switching of the power converter.

51. The apparatus of claim 45, wherein the controller further is, in response to a first input, to adjust an output brightness of the plurality of series of light-emitting diodes by modifying each corresponding period of time of current switching to each of the series of light-emitting diodes.

52. The apparatus of claim 45, wherein the controller further is, in response to a second input, to adjust an output color of the plurality of series of light-emitting diodes by modifying at least one corresponding period of time of current switching to at least one of the series of light-emitting diodes of the plurality of series of light-emitting diodes.