Systems and methods for calibrating light output by light-emitting diodes

• US 7,482,565 B2
• Filed: 02/22/2005
• Issued: 01/27/2009
• Est. Priority Date: 09/29/1999
• Status: Expired due to Term

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Philips Solid State Lighting Solutions Inc (Signify N.V.)
• Inventors: Lys, Ihor A., Morgan, Frederick M.
• Primary Examiner(s): Epps; Georgia Y
• Assistant Examiner(s): WYATT, KEVIN S
• Application Number:
  US11/064,069
• Publication Number:
  US 20060016960A1
• Time in Patent Office: 1,435 Days
• Field of Search: 250/205, 315/307, 315/291, 362/800, 362/231
• US Class Current: 250/205
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 2001/4252 for testing LED's
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A system and method for calibrating light output from an LED is provided. The system includes a support on which an LED is positioned, a photosensor to measure the light output from the LED, and means for calibrating and adjusting the light output of the LED. Calibration is accomplished by measuring the light output from the LED, comparing such output against a reference value, and adjusting the measured output against the reference value.

Claims

1. An apparatus, comprising:

at least one first LED to generate first radiation having a first spectrum;

at least one second LED to generate second radiation having a second spectrum different than the first spectrum;

at least one controller to control at least one of the first radiation and the second radiation so as to provide visible radiation emanating from the apparatus; and

at least one sensor to monitor at least one characteristic of sample radiation and provide at least one sensor signal to the at least one controller,

wherein the sample radiation includes at least some of the visible radiation emanating from the apparatus, such that the at least one sensor signal provides at least one feedback signal to the at least one controller,

wherein the at least one controller is configured to make a comparison of the at least one feedback signal and at least one reference value and formulate at least one calibration value based on the comparison, and

wherein the at least one controller uses the at least one calibration value, once formulated, to control the at least one of the first radiation and the second radiation without using the at least one feedback signal,

the apparatus further comprising at least one memory coupled to the at least one controller to store the at least one reference value and the at least one calibration value.

2. The apparatus of claim 1, wherein the visible radiation comprises substantially white light.

3. The apparatus of claim 1, wherein the at least one sensor is configured to wirelessly communicate the at least one sensor signal to the at least one controller.

4. The apparatus of claim 1, wherein the at least one sensor is configured to communicate the at least one sensor signal to the at least one controller and at least one other device that is responsive to the at least one sensor signal.

5. The apparatus of claim 1, wherein the at least one sensor includes at least one of a photosensor, a photometer, a spectrophotomoeter, a spectroradiometer, a spectrum analyzer, a spectrometer, a charge coupled device (CCD), a photodiode, a photocell and a thermocouple.

6. The apparatus of claim 1, wherein the at least one controller is configured as at least one addressable controller to receive at least one lighting command via a network connection based on an address of the at least one addressable controller, so as to control at least one of the first radiation and the second radiation.

7. The apparatus of claim 5, wherein the at least one lighting command is communicated over the network connection using a DMX protocol.

8. The apparatus of claim 1, wherein the at least one feedback signal represents an intensity of the sample radiation.

9. The apparatus of claim 1, wherein the at least one feedback signal represents a spectral property of the sample radiation.

10. The apparatus of claim 9, wherein the spectral property of the sample radiation relates to a color or color temperature of the sample radiation.

11. The apparatus of claim 1, wherein the at least one controller is configured to process the at least one feedback signal to determine a peak measurement associated with the sample radiation.

12. The apparatus of claim 1, wherein the at least one controller is configured to control at least one characteristic of the visible radiation based at least in part on the at least one feedback signal provided by the at least one sensor.

13. The apparatus of claim 12, further comprising at least one user interface coupled to the at least one controller to permit a user to control the visible radiation.

14. The apparatus of claim 13, wherein the visible radiation comprises substantially white light.

15. The apparatus of claim 12, further comprising an at least partially transparent housing that encloses at least the at least one first LED, the at least one second LED, and the at least one sensor.

16. The apparatus of claim 15, wherein the at least partially transparent housing is configured to resemble a conventional light bulb.

17. The apparatus of claim 15, wherein the at least partially transparent housing comprises at least one connector that is adapted to engage mechanically and electrically with a conventional light socket arrangement.

18. The apparatus of claim 1, wherein the at least one reference value represents an expected characteristic of the sample radiation.

19. The apparatus of claim 18, wherein the expected characteristic of the sample radiation relates to a performance metric associated with at least one of the at least one first LED and the at least one second LED.

20. The apparatus of claim 19, wherein the performance metric includes a bin associated with at least one of the at least one first LED and the at least one second LED.

21. The apparatus of claim 1, wherein the at least one reference value represents a previous calibration value.

22. The apparatus of claim 1, wherein the at least one reference value represents an ambient light condition.

23. The apparatus of claim 1, further including at least one user interface coupled to the at least one controller to permit a user to define the at least one reference value.

24. The apparatus of claim 1, wherein the at least one reference value includes a plurality of pre-programmed reference values that are stored in the at least one memory.

25. The apparatus of claim 24, wherein the plurality of pre-programmed reference values are stored in the at least one memory as a table of values representative of respective types of at least the at least one first LED and the at least one second LED.

26. The apparatus of claim 1, wherein the at least one controller is configured to strobe or flash at least the at least one first LED and the at least one second LED at predetermined intervals through a plurality of lighting conditions and monitor the at least one feedback signal.

27. The apparatus of claim 26, wherein the at least one controller is configured to strobe or flash at least the at least one first LED and the at least one second LED between different colors while monitoring the at least one feedback signal.

28. The apparatus of claim 1, wherein the at least one controller is configured to control at least the at least one first LED and the at least one second LED in a sequential fashion and wherein the at least one feedback signal includes at least a first feedback signal associated with the first radiation and a second feedback signal associated with the second radiation.

29. The apparatus of claim 28, wherein the at least one controller is configured to process at least the first feedback signal to determine a first peak measurement associated with the first radiation, and process the second feedback signal to determine a second peak measurement associated with the second radiation.

30. The apparatus of claim 28, wherein the at least one controller is configured to make a first comparison of the first feedback signal and a first reference value and formulate a first calibration value based on the first comparison, and make a second comparison of the second feedback signal and a second reference value and formulate a second calibration value based on the second comparison.

31. The apparatus of claim 1, wherein the at least one controller is configured to control at least one characteristic of the visible radiation based at least in part on the at least one calibration value.

32. The apparatus of claim 31, wherein the at least one controller includes calibration means for adjusting at least one of the first radiation and the second radiation, based on the at least one calibration value, such that the visible radiation has a calibrated color.

33. The apparatus of claim 32, wherein the visible radiation is a substantially white light, and wherein the calibration means is configured to adjust the at least one of the first radiation and the second radiation, based on the at least one calibration value, such that the visible radiation has a calibrated substantially white color.

34. The apparatus of claim 32, wherein the calibration means includes means for scaling the at least one of the first radiation and the second radiation so as to produce the calibrated color.

35. The apparatus of claim 32, wherein the calibration means includes means for adjusting commands sent to at least one of the at least one first LED and the at least one second LED, based on the at least one calibration value, so as to produce the calibrated color.

36. The apparatus of claim 32, wherein the at least one reference value is based on at least one ambient lighting condition.

37. The apparatus of claim 36, wherein the calibration means is configured to adjust the at least one of the first radiation and the second radiation, based on the at least one calibration value, such that the visible radiation approximates the at least one ambient lighting condition.

38. A method, comprising acts of:

A) energizing at least one first LED so as to generate first radiation having a first spectrum;

B) energizing at least one second LED so as to generate second radiation having a second spectrum different than the first spectrum;

C) monitoring at least one characteristic of sample radiation;

D) generating at least one feedback signal based on the act C), wherein the sample radiation includes at least some of the first radiation and/or the second radiation;

E) making a comparison of the at least one feedback signal and at least one reference value;

F) formulating at least one calibration value based on the comparison;

G) storing in memory at least the at least one reference value and the at least one calibration value; and

H) controlling the first radiation and/or the second radiation using the at least one calibration value and without using the at least one feedback signal.

39. The method of claim 38, wherein the act H) comprises an act of controlling at least one of the first radiation and the second radiation such that the visible radiation comprises substantially white light.

40. The method of claim 38, wherein the act H) includes an act of:

H1) processing at least one addressed lighting command communicated via a network connection so as to control at least one of the first radiation and the second radiation.

41. The method of claim 40, wherein the act H1) includes an act of:

communicating the least one lighting command over the network connection using a DMX protocol.

42. The method of claim 38, wherein the at least one characteristic includes an intensity of the sample radiation.

43. The method of claim 38, wherein the at least one characteristic includes a spectral property of the sample radiation.

44. The method of claim 43, wherein the spectral property of the sample radiation relates to a color or color temperature of the sample radiation.

45. The method of claim 38, further comprising an act of:

determining a peak measurement associated with the sample radiation based on the act C).

46. The method of claim 38, wherein the at least one reference value represents an expected characteristic of the sample radiation.

47. The method of claim 46, wherein the expected characteristic of the sample radiation relates to a performance metric associated with at least one of the at least one first LED and the at least one second LED.

48. The method of claim 47, wherein the performance metric includes a bin associated with at least one of the at least one first LED and the at least one second LED.

49. The method of claim 38, wherein the at least one reference value represents a previous calibration value.

50. The method of claim 38, wherein the at least one reference value represents an ambient light condition.

51. The method of claim 38, further comprising an act of permitting a user to define the at least one reference value.

52. The method of claim 38, wherein the at least one reference value includes a plurality of pre-programmed reference values, and wherein the act of storing includes an act of storing in the memory the plurality of pre-programmed reference values.

53. The method of claim 52, wherein the act of storing includes an act of storing the plurality of pre-programmed reference values as a table of values representative of respective types of at least the at least one first LED and the at least one second LED.

54. The method of claim 38, further comprising an act of:

strobing or flashing at least the at least one first LED and the at least one second LED at predetermined intervals through a plurality of lighting conditions while performing the act C).

55. The method of claim 54, wherein the act of strobing or flashing includes an act of strobing or flashing at least the at least one first LED and the at least one second LED between different colors while performing the act C).

56. The method of claim 38, further comprising an act of:

controlling at least the at least one first LED and the at least one second LED in a sequential fashion while performing the act C) so as to provide a first feedback signal associated with the first radiation and a second feedback signal associated with the second radiation.

57. The method of claim 56, further comprising acts of:

processing at least the first feedback signal to determine a first peak measurement associated with the first radiation; and

processing the second feedback signal to determine a second peak measurement associated with the second radiation.

58. The method of claim 57, further comprising acts of:

making a first comparison of the first feedback signal and a first reference value;

formulating a first calibration value based on the first comparison;

making a second comparison of the second feedback signal and a second reference value; and

formulating a second calibration value based on the second comparison.

59. The method of claim 38, wherein the act H) includes an act of:

H1) controlling at least one characteristic of the visible radiation based at least in part on the at least one calibration value.

60. The method of claim 59, wherein the act H1) includes an act of:

adjusting at least one of the first radiation and the second radiation, based on the at least one calibration value, such that the visible radiation has a calibrated color.

61. The method of claim 60, wherein the visible radiation is a substantially white light, and wherein the act of adjusting includes an act of adjusting the at least one of the first radiation and the second radiation, based on the at least one calibration value, such that the visible radiation has a calibrated substantially white color.

62. The method of claim 60, wherein the act H1) includes an act of:

scaling the at least one of the first radiation and the second radiation so as to produce the calibrated color.

63. The method of claim 60, wherein the act H1) includes an act of:

adjusting commands sent to at least one of the at least one first LED and the at least one second LED, based on the at least one calibration value, so as to produce the calibrated color.

64. The method of claim 60, wherein the at least one reference value is based on at least one ambient lighting condition.

65. The method of claim 64, wherein the act H1) includes an act of:

adjusting the at least one of the first radiation and the second radiation, based on the at least one calibration value, such that the visible radiation approximates the ambient lighting condition.