Color mixing of electronic light sources with correlation between phase-cut dimmer angle and predetermined black body radiation function

• US 8,912,734 B2
• Filed: 11/09/2012
• Issued: 12/16/2014
• Est. Priority Date: 03/24/2011
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Melanson, John L., Linz, Alfredo R., Kost, Michael A., Singh, Sahil
• Primary Examiner(s): TRAN, ANH Q
• Application Number:
  US13/673,879
• Publication Number:
  US 20130069561A1
• Time in Patent Office: 767 Days
• Field of Search: None
• US Class Current: 315/297
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: H05B 45/3577 Emulating the dimming characteristics, brightness or colour temperature of incandescent lamps
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• 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

Abstract

A lighting system includes methods and systems to mix colors of light emitted from at least two LED emitters. In at least one embodiment, the lighting system includes a controller that responds to phase-cut angles of the dimming signal and correlates the phase-cut angles with a predetermined black body radiation function to dynamically adjust a color spectra of the mixed light in response to changes in phase cut angles of the phase-cut dimming level signal. In at least one embodiment, the controller utilizes the predetermined black body radiation function to dynamically adjust the color spectra of the mixed, emitted light in response to changes in phase cut angles of a phase-cut dimming level signal. In at least one embodiment, the predetermined black body radiation function specifies correlated color temperatures (CCTs) that model the CCTs of an actual non-LED based lamp, such as an incandescent lamp.

Claims

1. An apparatus comprising:

a controller configured to;

receive a phase-cut dimming level signal; and

control a first drive current to a first light emitting diode (“

LED”

) emitter and a second drive current to a second LED emitter to control a color of mixed light emitted from the two LED emitters by responding to phase-cut angles of the dimming signal and correlating the phase-cut angles with a predetermined black body radiation function to dynamically adjust a color spectra of the mixed light in response to changes in phase cut angles of the phase-cut dimming level signal, wherein during operation of the LED emitters, the two LED emitters emit light having at least three dominant wavelengths representing at least three different colors.

2. The apparatus of claim 1 wherein the first LED emitter includes only one LED and the second LED emitter includes only one LED and to control the color of mixed light emitted from the two LED emitters further comprises to:

apply a predetermined black body radiation function to correlate the dimming level signal with at least first and second LED drive current levels;

control a first LED drive current to the first LED emitter corresponding to the first LED drive current level; and

control a second LED drive current to the second LED emitter corresponding to the second LED drive current level.

3. The apparatus of claim 2 wherein the controller is further configured to apply the predetermined black body radiation function to correlate the dimming level signal with a third light emitting diode (“

LED”

) drive current levels, and the controller is further configured to;

control a third LED drive current to a third LED emitter corresponding to the third LED drive current level, wherein during operation the first, second, and third LED emitters emit light having respective dominant wavelengths representing at least three different colors.

4. The apparatus of claim 3 wherein each dimming level signal correlates with one combination of the first, second, and third LED drive current levels.

5. The apparatus of claim 2 wherein the controller is further configured to:

respond to changes in the dimming level signal by applying the predetermined black body radiation function to re-correlate the dimming level signal with revised first and second LED drive current levels.

6. The apparatus of claim 2 wherein the controller is further configured to:

receive a selection of one or multiple predetermined black body radiation functions; and

apply the selected predetermined black body radiation function to correlate the dimming level signal with the first and second LED drive current levels.

7. The apparatus of claim 2 wherein the controller is further configured to:

receive data that modifies the predetermined black body radiation function; and

apply the modified predetermined black body radiation function to correlate the dimming level signal with the first and second LED drive current levels.

8. The apparatus of claim 1 wherein the controller is further configured to:

receive a selection of one or multiple predetermined black body radiation functions; and

correlate the phase-cut angles with the selected predetermined black body radiation function.

9. The apparatus of claim 1 wherein the at least one controller is further configured to:

receive data that modifies the predetermined black body radiation function; and

correlate the phase-cut angles with the modified predetermined black body radiation function.

10. The apparatus of claim 1 wherein the predetermined black body radiation function comprises a curve that approximates a black body radiation curve of an incandescent bulb from approximately 5,000 Kelvin to 1,500 Kelvin.

11. The apparatus of claim 1 wherein each of the dimming level signals is within one of multiple ranges of dimming level signals, and each range of dimming level signals correlates with one combination of the first and second drive current levels.

12. The apparatus of claim 1 further comprising a memory coupled to the controller, wherein the predetermined black body radiation function is represented by a map that correlates dimming level signal values to first and second LED drive current levels, the memory stores the map, and to correlate the dimming level signal with the first and second LED drive current levels, the controller is configured to:

retrieve data from the map in the memory that corresponds to the dimming level signal values.

13. The apparatus of claim 1 further comprising a memory coupled to the controller, wherein the predetermined black body radiation function is represented by an algorithm stored in the memory, and to correlate the dimming level signal values to first and second LED drive current levels, the controller is configured to:

calculate the first and second LED drive current levels using the dimming signal level and the predetermined black body radiation function.

14. The apparatus of claim 1 wherein the first LED emitter includes a first LED and also includes a lumiphor, and light exiting the first LED emitter is emitted by the LED with a first dominant wavelength corresponding to a first color and by the lumiphor with a second dominant wavelength corresponding to a second color.

15. The apparatus of claim 1 wherein to control the color of mixed light emitted from the two LED emitters further comprises to:

apply the predetermined black body radiation function to correlate the dimming level signal with two LED drive current levels.

16. The apparatus of claim 1 wherein a first of the LED emitters includes a first LED and a second LED, a second of the LED emitters includes a third LED and a fourth LED, and to control the color of mixed light emitted from the two LED emitters further comprises to:

control a first LED drive current to the first LED, wherein the first LED emits a red color;

control a second LED drive current to the second LED, wherein the second emits a blue color and also includes a lumiphor that converts part of the blue color emission from the blue LED to a green color.

17. The apparatus of claim 1 wherein the predetermined black body radiation function is non-linear.

18. The apparatus of claim 1 wherein a plurality of the phase-cut angles each correspond to different correlated color temperatures of the predetermined black body radiation function.

19. An method comprising:

receiving a phase-cut dimming level signal; and

controlling a first drive current to a first light emitting diode (“

LED”

) emitter and a second drive current to a second LED emitter to control a color of mixed light emitted from the two LED emitters by responding to phase-cut angles of the dimming signal and correlating the phase-cut angles with a predetermined black body radiation function to dynamically adjust a color spectra of the mixed light in response to changes in phase cut angles of the phase-cut dimming level signal, wherein during operation of the LED emitters, the two LED emitters emit light having at least three dominant wavelengths representing at least three different colors.

20. The method of claim 19 wherein the first LED emitter includes only one LED and the second LED emitter includes only one LED and controlling the color of mixed light emitted from the at least two LED emitters further comprises:

applying a predetermined black body radiation function to correlate the dimming level signal with at least first and second LED drive current levels;

controlling a first LED drive current to the first LED emitter corresponding to the first LED drive current level; and

controlling a second LED drive current to the second LED emitter corresponding to the second LED drive current level.

21. The method of claim 20 further comprising:

applying the predetermined black body radiation function to correlate the dimming level signal with a third LED drive current levels; and

controlling a third LED drive current to a third LED emitter corresponding to the third LED drive current level, wherein during operation the first, second, and third LED emitters emit light having respective dominant wavelengths representing at least three different colors.

22. The method of claim 21 wherein each dimming level signal correlates with one combination of the first, second, and third LED drive current levels.

23. The method of claim 21 further comprising:

responding to changes in the dimming level signal by applying the predetermined black body radiation function to re-correlate the dimming level signal with revised first and second LED drive current levels.

24. The method of claim 21 further comprising:

receiving a selection of one or multiple predetermined black body radiation functions; and

applying the selected predetermined black body radiation function to correlate the dimming level signal with the first and second LED drive current levels.

25. The method of claim 21 further comprising:

receiving data that modifies the predetermined black body radiation function; and

applying the modified predetermined black body radiation function to correlate the dimming level signal with the first and second LED drive current levels.

26. The method of claim 20 further comprising:

receiving a selection of one or multiple predetermined black body radiation functions; and

correlating the phase-cut angles with the selected predetermined black body radiation function.

27. The method of claim 20 further comprising:

receiving data that modifies the predetermined black body radiation function; and

correlating the phase-cut angles with the modified predetermined black body radiation function.

28. The method of claim 20 wherein the predetermined black body radiation function comprises a curve that approximates a black body radiation curve of an incandescent bulb from approximately 5,000 Kelvin to 1,500 Kelvin.

29. The method of claim 20 wherein each of the dimming level signals is within one of multiple ranges of dimming level signals, and each range of dimming level signals correlates with one combination of the first and second third LED drive current levels.

30. The method of claim 20 wherein the predetermined black body radiation function is represented by a map that correlates dimming level signal values to first and second LED drive current levels, a memory stores the map, and correlating the phase-cut angles with the first and second LED drive current levels comprises:

retrieving data from the map in the memory that corresponds to the dimming level signal values.

31. The method of claim 20 wherein the predetermined black body radiation function is represented by an algorithm stored in a memory, and correlating the phase-cut angles to first and second LED drive current levels comprises:

calculating first and second LED drive current levels using the dimming signal level and the predetermined black body radiation function.

32. The method of claim 20 wherein the first LED emitter includes a first LED and also includes a lumiphor, and light exiting the first LED emitter is emitted by the LED with a first dominant wavelength corresponding to a first color and by the lumiphor with a second dominant wavelength corresponding to a second color.

33. The method of claim 20 wherein to control the color of mixed light emitted from the two LED emitters further comprises to:

apply the predetermined black body radiation function to correlate the dimming level signal with two LED drive current levels.

34. The method of claim 20 wherein a first of the LED emitters includes a first LED and a second LED, a second of the LED emitters includes a third LED and a fourth LED, and controlling the color of mixed light emitted from the two LED emitters further comprises:

controlling a first LED drive current to the first LED, wherein the first LED emits a red color;

controlling a second LED drive current to the second LED, wherein the second emits a blue color and also includes a lumiphor that converts part of the blue color emission from the blue LED to a green color.

35. The method of claim 20 wherein the predetermined black body radiation function is non-linear.

36. The method of claim 20 wherein a plurality of the phase-cut angles each correspond to different correlated color temperatures of the predetermined black body radiation function.

37. A lighting system comprising:

a switching power converter;

at least two light emitting diode (“

LED”

) emitters; and

a controller configured to;

receive a phase-cut dimming level signal; and

control a first drive current to a first light emitting diode (“

LED”

) emitter and a second drive current to a second LED emitter to control a color of mixed light emitted from the two LED emitters by responding to phase-cut angles of the dimming signal and correlating the phase-cut angles with a predetermined black body radiation function to dynamically adjust a color spectra of the mixed light in response to changes in phase cut angles of the phase-cut dimming level signal, wherein during operation of the LED emitters, the two LED emitters emit light having at least three dominant wavelengths representing at least three different colors.