System and Method for Regulation of Solid State Lighting

• US 20110115394A1
• Filed: 08/18/2010
• Published: 05/19/2011
• Est. Priority Date: 09/21/2007
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Exclara, Inc. (Million Star Technology Ltd.)
• Inventors: Rodriguez, Harry, Shteynberg, Anatoly, Zhou, Dongsheng, Lehman, Bradley M.
• Granted Patent: US 8,253,349 B2
• Time in Patent Office: Days
• US Class Current: 315/250
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• 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

Exemplary embodiments of the invention provide a system, apparatus, and method of controlling an intensity and spectrum of light emitted from a solid state lighting system. The solid state lighting has a first emitted spectrum at full intensity and at a selected temperature, with a first electrical biasing for the solid state lighting producing a first wavelength shift, and a second electrical biasing for the solid state lighting producing a second, opposing wavelength shift. Exemplary embodiments provide for receiving information designating a selected intensity level or a selected temperature; and providing a combined first electrical biasing and second electrical biasing to the solid state lighting to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum over a predetermined range of temperatures.

Claims

1. A method of varying an intensity of light emitted from at least one or more substantially similar light emitting diodes, a first electrical biasing for the at least one or more substantially similar light emitting diodes producing a first wavelength shift, a second electrical biasing for the at least one or more substantially similar light emitting diodes producing a second, opposing wavelength shift, the method comprising:

monitoring an input control signal, the input control signal designating a selected intensity level;

retrieving a plurality of parameters stored in a memory, the plurality of parameters designating a corresponding combination of the first electrical biasing and the second electrical biasing for the selected intensity level;

processing the plurality of parameters into at least one input electrical biasing control signal; and

operating the at least one or more substantially similar light emitting diodes with a time-averaged modulation of forward current conforming to the at least one input electrical biasing control signal to provide the selected intensity level within a dimming cycle.

2. The method of claim 1, wherein emitted light from the at least one or more substantially similar light emitting diodes at the selected intensity level has a peak wavelength within a predetermined variance of a full intensity peak wavelength.

3. The method of claim 1, wherein the input control signal is provided by at least one of the following:

a lighting controller, a microprocessor, a remote controller, an AC phase modulation controller, or a manual controller.

4. The method of claim 1, wherein the input control signal has an analog or digital form compatible with an input interface of a controller of an LED driver.

5. The method of claim 1, further comprising:

selecting the first electrical biasing for corresponding p-n junctions of the at least one or more substantially similar light emitting diodes to produce the first wavelength shift in response to variation of the intensity level; and

selecting the second electrical biasing for the corresponding p-n junctions of the at least one or more substantially similar light emitting diodes to produce the second, opposing wavelength shift in response to variation of the intensity level.

6. The method of claim 5, further comprising:

statistically characterizing the at least one or more substantially similar light emitting diodes for the first electrical biasing and the second electrical biasing as a function of intensity levels.

7. The method of claim 6, further comprising:

theoretically predicting the combination of the first electrical biasing and the second electrical biasing to control both intensity and wavelength shifts.

8. The method of claim 7, further comprising:

theoretically predicting the combination of the first electrical biasing and the second electrical biasing to control intensity and to provide any wavelength shifts are substantially close to zero.

9. The method of claim 7, further comprising:

storing the predicted combination as the plurality of parameters in the memory of a controller for a driver circuit for the at least one or more substantially similar light emitting diodes.

10. The method of claim 7, further comprising:

storing the predicted combination as the plurality of parameters in the form of a look up table.

11. The method of claim 7, further comprising:

storing the predicted combination as at least one linear or functional equation for intensity adjustment within every dimming cycle or every second dimming cycle for the first electrical biasing and the second electrical biasing.

12. The method of claim 6, further comprising:

theoretically predicting the operation of the at least one or more substantially similar light emitting diodes from the application of the combination of the first electrical biasing and the second electrical biasing during symmetrical or asymmetrical dimming cycles for a predetermined range of intensity variation.

13. The method of claim 1, wherein the first electrical biasing and the second electrical biasing are a forward current or bias voltage of the at least one or more substantially similar light emitting diodes.

14. The method of claim 1, wherein the first electrical biasing is an adaptation of an average DC current using any waveform of analog current control.

15. The method of claim 1, wherein the second electrical biasing is a pulse modulated current.

16. The method of claim 1, wherein the second electrical biasing is at least one of the following:

pulse width modulation, pulse frequency modulation, pulse amplitude modulation, or a time-averaged pulse modulated current.

17. The method of claim 1, wherein the corresponding combination of the first electrical biasing and the second electrical biasing is a combination of non-zero signals of the first electrical biasing and the second electrical biasing which regulate wavelength emission while maintaining a substantially constant average intensity of the at least one or more substantially similar light emitting diodes.

18. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing is a combination of pulse width modulation and constant current regulation within a single dimming cycle.

19. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing is a combination of forward current pulse modulation and analog regulation alternating every two consecutive dimming cycles.

20. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing is a combination of forward current pulse modulation and analog regulation alternating every three consecutive dimming cycles.

21. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing is a combination of forward current pulse modulation and analog regulation alternating an equal number of consecutive dimming cycles.

22. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing is a combination of forward current pulse modulation and analog regulation alternating an unequal number of consecutive dimming cycles.

23. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing further comprises forward current pulse modulation with a peak current in a high state and an average current value at a low state.

24. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing further comprises alternating each second dimming cycle a combination of forward current pulse modulation and analog regulation of forward current with any arbitrary waveform having an average DC component.

25. The method of claim 1, further comprising:

synchronizing the combination of the first electrical biasing and second electrical biasing with a switching cycle of a switch mode LED driver.

26. The method of claim 25, wherein the combination of the first electrical biasing and second electrical biasing has a duty cycle and an average current level which are related to the selected intensity level according to a first relation of

27. The method of claim 1, wherein the combination of the first electrical biasing and second electrical biasing is a superposition of an AC signal on a DC signal.

28. The method of claim 1, wherein the operation of the at least one or more substantially similar light emitting diodes with a time-averaged modulation of forward current conforming to the at least one input electrical biasing control signal further provides a selected lighting effect.

29. A lighting system having variable intensity, the system comprising:

at least one or more substantially similar light emitting diodes connected in a channel, a first electrical biasing for the at least one or more substantially similar light emitting diodes producing a first wavelength shift, and a second electrical biasing for the at least one or more substantially similar light emitting diodes producing a second, opposing wavelength shift;

at least one driver circuit coupled to the at least one or more substantially similar light emitting diodes, the at least one driver circuit comprising a regulator and a power converter, the driver circuit adapted to respond to a plurality of input operational signals to provide a selected combination of the first electrical biasing and the second electrical biasing to the at least one or more substantially similar light emitting diodes; and

at least one controller couplable to a user interface and coupled to the at least one driver circuit, the at least one controller further comprising a memory, the at least one controller adapted to retrieve a plurality of parameters stored in a memory, the plurality of parameters corresponding to a selected intensity level provided by the user interface and designating the selected combination of the first electrical biasing and the second electrical biasing;

the at least one controller further adapted to convert the plurality of parameters into at least one input operational control signal to provide the selected intensity level with wavelength emission control.

30. The system of claim 29, wherein the plurality of input operational signals provide at least one of the following:

switching frequency, output current, output voltage, modulation duty cycle, modulation amplitude, modulation frequency, or dimming cycle.

31. The system of claim 29, wherein emitted light from the at least one or more substantially similar light emitting diodes at the selected intensity level has a peak wavelength within a predetermined variance of a full intensity peak wavelength.

32. The system of claim 29, wherein the user interface comprises at least one of the following:

a lighting controller, a microprocessor, a remote controller, an AC phase modulation controller, or a manual controller.

33. The system of claim 29, wherein the plurality of parameters are a prediction of the combination of the first electrical biasing and the second electrical biasing to control both intensity and wavelength shifts.

34. The system of claim 29, wherein the plurality of parameters are a prediction of the combination of the first electrical biasing and the second electrical biasing to control intensity and to provide any wavelength shifts are substantially close to zero.

35. The system of claim 29, wherein the plurality of parameters are stored in the form of a look up table in the memory.

36. The system of claim 29, wherein the plurality of parameters are stored in the form of at least one linear or functional equation for intensity adjustment within every dimming cycle or every second dimming cycle for the first electrical biasing and the second electrical biasing.

37. The system of claim 29, wherein the plurality of parameters are a prediction of the operation of the at least one or more substantially similar light emitting diodes from the application of the combination of the first electrical biasing and the second electrical biasing during symmetrical or asymmetrical dimming cycles for a predetermined range of intensity variation.

38. The system of claim 29, wherein the first electrical biasing and the second electrical biasing are a forward current or bias voltage of the at least one or more substantially similar light emitting diodes.

39. The system of claim 29, wherein the first electrical biasing is an adaptation of an average DC current using any waveform of analog current control.

40. The system of claim 29, wherein the second electrical biasing is a pulse modulated current.

41. The system of claim 29, wherein the second electrical biasing is at least one of the following:

pulse width modulation, pulse frequency modulation, pulse amplitude modulation, or a time-averaged pulse modulated current.

42. The system of claim 29, wherein the corresponding combination of the first electrical biasing and the second electrical biasing is a combination of non-zero signals of the first electrical biasing and the second electrical biasing which regulate wavelength emission while maintaining a substantially constant average intensity of the at least one or more substantially similar light emitting diodes.

43. The system of claim 29, wherein the combination of the first electrical biasing and second electrical biasing is at least one of the following:

a combination of pulse width modulation and constant current regulation within a single dimming cycle;

a combination of forward current pulse modulation and analog regulation alternating every two consecutive dimming cycles;

a combination of forward current pulse modulation and analog regulation alternating every three consecutive dimming cycles;

a combination of forward current pulse modulation and analog regulation alternating an equal number of consecutive dimming cycles;

or a combination of forward current pulse modulation and analog regulation alternating an unequal number of consecutive dimming cycles.

44. The system of claim 29, wherein the combination of the first electrical biasing and second electrical biasing further comprises forward current pulse modulation with a peak current in a high state and an average current value at a low state.

45. The system of claim 29, wherein the controller is further adapted to generate at least one control signal providing that the combination of the first electrical biasing and second electrical biasing is an alternation each second dimming cycle a combination of forward current pulse modulation and analog regulation of forward current with any arbitrary waveform having an average DC component.

46. The system of claim 29, wherein the controller is further adapted to synchronize the combination of the first electrical biasing and second electrical biasing with a switching cycle of the driver circuit.

47. The system of claim 46, wherein the combination of the first electrical biasing and second electrical biasing has a duty cycle and an average current level which are related to the selected intensity level according to a first relation of

48. The system of claim 29, wherein the combination of the first electrical biasing and second electrical biasing is a superposition of an AC signal on a DC signal.

49. The system of claim 29, wherein the at least one controller is further adapted to generate the at least one input electrical biasing control signal to further provide a selected lighting effect.

50. The system of claim 29, wherein the at least one controller is further adapted to generate the at least one input electrical biasing control signal to control the wavelength of the emitted light within a predetermined variance and subject to a plurality of selected intensity levels.

51. The system of claim 29, wherein the at least one controller is further adapted to generate the at least one input electrical biasing control signal to maintain the wavelength of the emitted light substantially constant over a predetermined range of selected intensity levels.

52. The system of claim 29, wherein the driver circuit is a switch mode driver circuit and the combination of the first electrical biasing and second electrical biasing is a superposition of analog regulation and pulse modulation of forward current in each dimming cycle of the driver circuit.

53. The system of claim 29, wherein the at least one controller further comprises:

a dimming frame register;

an intensity register;

a programmable look up table memory;

a programmable frame counter and cycle counter;

a block of operational signal registers;

at least one analog multiplexer; and

at least one digital-to-analog converter.

54. The system of claim 53, wherein the at least one controller is further adapted to program the operational signal registers with at least two peak current amplitude values, at least two current amplitude modulation values, and two current duty cycle values to provide the at least one input operational control signal to the driver circuit to provide the combination of the first electrical biasing and the second electrical biasing for the selected intensity level and emission wavelength control specified by the user interface.

55. The system of claim 54, wherein the at least one controller is further adapted to vary the intensity of the at least one or more substantially similar light emitting diodes without substantial optical output flickering by alternatively multiplexing the at least one input operational control signal to the driver circuit from a first set of operational signal registers synchronously to an end of a current dimming frame counter while programming asynchronously a second set of operational signal registers with a second input operational control signal.

56. The system of claim 29, wherein the at least one controller is further adapted to queue the second input operational control signal to a current status at the end of the current dimming frame counter.

57. The system of claim 29, wherein the user interface is couplable to a microprocessor or a network using a proprietary or standard interface protocol including DMX 512, DALI, I²C, or SPI.

58. The system of claim 29, wherein the power converter of the at least one driver circuit is a linear circuit, a switching DC/DC circuit, or a switching AC/DC circuit with a power factor correction circuit.

59. The system of claim 29, further comprising:

at least one temperature sensor coupled to the at least one or more substantially similar light emitting diodes and to the at least one controller.

60. The system of claim 59, wherein the at least one controller is further adapted to generate the at least one input operational control signal to maintain the selected intensity level and wavelength emission over a predetermined range of junction temperatures of the at least one or more substantially similar light emitting diodes.

61. The system of claim 29, further comprising:

an enclosure for the at least one or more substantially similar light emitting diodes, the at least one controller and the at least one driver circuit, the enclosure having a terminal couplable to an input power signal.

62. The system of claim 61, wherein the input power signal is an AC utility signal.

63. The system of claim 61, wherein the system is couplable to a phase modulation device and the input power signal is a phase-modulated AC utility signal.

64. The system of claim 61, wherein the enclosure is compatible with a standard light bulb interface.

65. The system of claim 61, wherein the enclosure is compatible with a standard Edison light bulb socket.

66. An illumination control method for at least one or more substantially similar light emitting diodes providing emitted light, a first electrical biasing for the at least one or more substantially similar light emitting diodes producing a first wavelength shift, a second electrical biasing for the at least one or more substantially similar light emitting diodes producing a second, opposing wavelength shift, the method comprising:

monitoring an input control signal, the input control signal designating a selected lighting effect;

retrieving a plurality of parameters stored in a memory, the plurality of parameters designating a corresponding combination of the first electrical biasing and the second electrical biasing for the selected lighting effect;

processing the plurality of parameters into at least one input electrical biasing control signal; and

operating the at least one or more substantially similar light emitting diodes with a time-averaged modulation of forward current conforming to the at least one input electrical biasing control signal to provide the selected lighting effect within a dimming cycle.

67. A method of controlling an intensity of light emitted from at least one or more substantially similar light emitting diodes with compensation for spectral changes due to temperature variation, the at least one or more substantially similar light emitting diodes having a first emitted spectrum at full intensity, a first electrical biasing for the at least one or more substantially similar light emitting diodes producing a first wavelength shift, a second electrical biasing for the at least one or more substantially similar light emitting diodes producing a second, opposing wavelength shift, the method comprising:

monitoring an input control signal, the input control signal designating a selected intensity level;

determining a temperature associated with the at least one or more substantially similar light emitting diodes;

retrieving a plurality of parameters stored in a memory, the plurality of parameters designating a corresponding combination of the first electrical biasing and the second electrical biasing for the selected intensity level and the determined temperature;

processing the plurality of parameters into at least one input electrical biasing control signal; and

operating the at least one or more substantially similar light emitting diodes with a time-averaged modulation of forward current conforming to the at least one input electrical biasing control signal to provide the selected intensity level over a predetermined range of temperatures and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.

68. The method of claim 67, wherein emitted light from the at least one or more substantially similar light emitting diodes at the selected intensity level has a peak wavelength within the predetermined variance of a full intensity peak wavelength.

69. The method of claim 67, wherein the determination of the temperature further comprises:

sensing at least one junction temperature associated with the at least one or more substantially similar light emitting diodes.

70. The method of claim 67, wherein the determination of the temperature further comprises:

sensing at least one device temperature associated with the at least one or more substantially similar light emitting diodes.

71. The method of claim 67, further comprising:

selecting the first electrical biasing for corresponding p-n junctions of the at least one or more substantially similar light emitting diodes to produce the first wavelength shift in response to variation of the intensity level and a variation of temperature; and

selecting the second electrical biasing for the corresponding p-n junctions of the at least one or more substantially similar light emitting diodes to produce the second, opposing wavelength shift in response to variation of the intensity level and a variation of temperature.

72. The method of claim 71, further comprising:

statistically characterizing the at least one or more substantially similar light emitting diodes for the first electrical biasing and the second electrical biasing as a function of intensity levels and temperature variation.

73. The method of claim 72, further comprising:

theoretically predicting the combination of the first electrical biasing and the second electrical biasing to control both intensity and wavelength shifts over temperature variation.

74. The method of claim 73, further comprising:

theoretically predicting the combination of the first electrical biasing and the second electrical biasing to control intensity and to provide any wavelength shifts are substantially close to zero over temperature variation.

75. The method of claim 73, further comprising:

storing the predicted combination as the plurality of parameters in the memory of a controller for a driver circuit for the at least one or more substantially similar light emitting diodes.

76. The method of claim 73, further comprising:

storing the predicted combination as the plurality of parameters in the form of a look up table.

77. The method of claim 73, further comprising:

storing the predicted combination as at least one linear or functional equation for intensity adjustment within every dimming cycle or every second dimming cycle for the first electrical biasing and the second electrical biasing.

78. The method of claim 67, wherein the first electrical biasing and the second electrical biasing are a forward current or bias voltage of the at least one or more substantially similar light emitting diodes.

79. The method of claim 67, wherein the first electrical biasing is an adaptation of an average DC current using any waveform of analog current control and wherein the second electrical biasing is a pulse modulated current.

80. The method of claim 67, wherein the corresponding combination of the first electrical biasing and the second electrical biasing is a combination of non-zero signals of the first electrical biasing and the second electrical biasing which regulate wavelength emission while maintaining a substantially constant average intensity of the at least one or more substantially similar light emitting diodes.

81. The method of claim 67, wherein the operation of the at least one or more substantially similar light emitting diodes with a time-averaged modulation of forward current conforming to the at least one input electrical biasing control signal further provides a selected lighting effect.

82. The method of claim 67, wherein the operating step further comprises:

maintaining the selected intensity substantially constant.

83. The method of claim 67, further comprising:

retrieving a second plurality of parameters stored in a memory, the plurality of parameters designating a corresponding combination of the first electrical biasing and the second electrical biasing for a new selected intensity level and the determined temperature;

processing the second plurality of parameters into at least one input electrical biasing control signal; and

operating the at least one or more substantially similar light emitting diodes with a time-averaged modulation of forward current conforming to the at least one input electrical biasing control signal to provide the new selected intensity level over a predetermined range of temperatures and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.