Color coordination of electronic light sources with dimming and temperature responsiveness

• US 8,823,289 B2
• Filed: 03/26/2012
• Issued: 09/02/2014
• Est. Priority Date: 03/24/2011
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Linz, Alfredo R., Kost, Michael A., Singh, Sahil
• Primary Examiner(s): TRAN, ANH Q
• Application Number:
  US13/430,601
• Publication Number:
  US 20120242242A1
• Time in Patent Office: 890 Days
• Field of Search: None
• US Class Current: 315/309
• 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 45/3725 Switched mode power supply [SMPS]

Abstract

A lighting system includes one or more methods and systems to control the color spectrum of a lamp in response to both temperature and dim levels. In at least one embodiment, the lighting system includes a controller to control a correlated color temperature (CCT) and intensity of the lamp by independently adjusting currents to electronic light sources based on a dim level of the lighting system and temperature of the lighting system. The controller controls a first current to a first set of LEDs and a second current to a second set of LEDs. The control of the first current by the controller is jointly dependent on a dim level and temperature in the lighting system. In at least one embodiment, the control of the second current is dependent on the dim level or the dim level and temperature.

Claims

1. A lighting system comprising:

a controller capable of controlling a first current to a first set of one or more electronic light sources and controlling a second current to a second set of one or more electronic light sources, wherein;

control of the first current by the controller is jointly dependent on a dim level and a temperature in the lighting system;

control of the second current by the controller is dependent on the dim level in the lighting system and control of the second current by the controller includes determining a value of the second current in accordance with a first function that does not adjust the second current in accordance with the temperature of the lighting system;

the first set of one or more electronic light sources has a first correlated color temperature (CCT); and

the second set of one or more electronic light sources has a second CCT.

2. The lighting system of claim 1 wherein the controller is capable of controlling the first current to control the first CCT and brightness by determining a value of the first current in accordance with a second function that represents a joint dependency of the first current and at least the temperature and the dim level.

3. The lighting system of claim 1 wherein the controller comprises:

a digital signal processor; and

a memory coupled to the digital signal processor, wherein the memory stores coefficients of the first and second functions, and, during operation, the digital signal processor utilizes the first and second functions and coefficients to determine a first control signal to control the first current and a second control signal to control the second current.

4. The lighting system of claim 3 wherein the lighting system comprises a lamp that houses at least the controller and the first and second sets of the electronic light sources and the lamp is configured to receive at least a portion of the coefficients during calibration of the lamp after the lamp is fully assembled.

5. The lighting system of claim 2 wherein the second function represents a map of a three dimensional, jointly dependent relationship between the temperature, the dim level, and a parameter related to at least the first current.

6. The lighting system of claim 5 wherein the first function represents a map of a line curve representing a relationship between the dim level and a parameter related to at least the first current.

7. The lighting system of claim 5 wherein the map represents a nonlinear relationship between the temperature, the dim level, and a parameter related to at least the first current.

8. The lighting system of claim 7 wherein the nonlinear relationship is defined using polynomial approximations.

9. The lighting system of claim 5 wherein the parameter related to at least the first current is a gain of the first current.

10. The lighting system of claim 2 wherein the first and second set of electronic light sources are contained within a lamp, and the controller is capable of adjusting the first current and the second current to maintain an approximately constant CCT of the lamp as the temperature changes.

11. The lighting system of claim 1 wherein the controller is capable of controlling the first current independently of the second current.

12. The lighting system of claim 1 wherein the controller is capable of controlling the first and second currents to coordinate changes in the first and second color spectrum in response to changes in the dim level.

13. The lighting system of claim 1 wherein the controller is capable of utilizing at least jointly dependent temperature and dim level variables of the lighting system to control the first current to the first set of the one or more electronic light sources.

14. The lighting system of claim 1 wherein the first set of one or more electronic light sources comprises one or more light emitting diodes and the second set of one or more electronic light sources comprises one or more light emitting diodes.

15. The lighting system of claim 1 wherein the temperature represents an ambient temperature within a housing that houses the first and second sets of electronic light sources.

16. The lighting system of claim 1 wherein the dim level is a dim level for the lighting system.

17. The lighting system of claim 16 wherein the dim level is a function of a phase angle of a phase modulated supply voltage to the lighting system.

18. The lighting system of claim 1 wherein the controller is further capable of generating a control signal to control a power converter.

19. The lighting system of claim 18 wherein the power converter is a member of a group consisting of:

a boost switching power converter, a buck switching power converter, a flyback switching power converter, a boost-buck switching power converter, and a Cú

k switching power converter.

20. The lighting system of claim 1 wherein the controller is capable of utilizing the at least jointly dependent temperature and dim level variables of the lighting system to control N sets of one or more electronic light sources, wherein N is an integer greater than or equal to 2.

30. The method of claim 2 wherein the first and second set of electronic light sources are contained within a lamp and the method further comprises:

adjusting the first current and the second current to maintain an approximately constant CCT of the lamp as the temperature changes.

21. A method comprising:

controlling a first current to a first set of one or more electronic light sources and controlling a second current to a second set of one or more electronic light sources in a lighting system, wherein;

control of the first current by the controller is jointly dependent on a dim level and a temperature in the lighting system;

control of the second current by the controller is dependent on the dim level in the lighting system and control of the second current by the controller includes determining a value of the second current in accordance with a first function that does not adjust the second current in accordance with the temperature of the lighting system;

the first set of one or more electronic light sources has a first correlated color temperature (CCT); and

the second set of one or more electronic light sources has a second CCT.

22. The method of claim 21 further comprising:

controlling the first current to control the first CCT and brightness by determining a value of the first current in accordance with a second function that represents a joint dependency of the first current and at least the temperature and the dim level.

23. The method of claim 22 further comprising:

storing coefficients of the first and second functions in a memory of a controller configured to control a switching power converter; and

utilizing the first and second functions and coefficients to determine a first control signal to control the first current and a second control signal to control the second current.

24. The method of claim 23 further comprising:

receiving at least a portion of the coefficients in a lamp during calibration of the lamp after the lamp is fully assembled.

25. The method of claim 22 wherein the second function represents a map of a three dimensional, jointly dependent relationship between the temperature, the dim level, and a parameter related to at least the first current.

26. The method of claim 25 wherein the first function represents a map of a line curve representing a relationship between the dim level and a parameter related to at least the first current.

27. The method of claim 25 wherein the map represents a nonlinear relationship between the temperature, the dim level, and a parameter related to at least the first current.

28. The method of claim 27 wherein the nonlinear relationship is defined using polynomial approximations.

29. The method of claim 25 wherein the parameter related to at least the first current is a gain of the first current.

31. The method of claim 21 further comprising:

controlling the first current independently of the second current.

32. The method of claim 21 further comprising:

controlling the first and second currents to coordinate changes in the first and second color spectrum in response to changes in the dim level.

33. The method of claim 21 further comprising:

utilizing at least jointly dependent temperature and dim level variables of the lighting system to control the first current to the first set of the one or more electronic light sources.

34. The method of claim 21 wherein the first set of one or more electronic light sources comprises one or more light emitting diodes and the second set of one or more electronic light sources comprises one or more light emitting diodes.

35. The method of claim 21 wherein the temperature represents an ambient temperature within a housing that houses the first and second sets of electronic light sources.

36. The method of claim 21 wherein the dim level is a dim level for the lighting system.

37. The method of claim 36 wherein the dim level is a function of a phase angle of a phase modulated supply voltage to the lighting system.

38. The method of claim 21 further comprising:

generating a control signal to control a power converter.

39. The method of claim 38 wherein the power converter is a member of a group consisting of:

a boost switching power converter, a buck switching power converter, a flyback switching power converter, a boost-buck switching power converter, and a Cú

k switching power converter.

40. The method of claim 21 further comprising:

utilizing the at least jointly dependent temperature and dim level variables of the lighting system to control N sets of one or more electronic light sources, wherein N is an integer greater than or equal to 2.

41. An apparatus comprising:

means for controlling a first current to a first set of one or more electronic light sources and controlling a second current to a second set of one or more electronic light sources in a lighting system, wherein;

control of the first current by the controller is jointly dependent on a dim level and a temperature in the lighting system;

control of the second current by the controller is dependent on the dim level in the lighting system and control of the second current by the controller includes determining a value of the second current in accordance with a first function that does not adjust the second current in accordance with the temperature of the lighting system;

the first set of one or more electronic light sources has a first correlated color temperature (CCT); and

the second set of one or more electronic light sources has a second CCT.