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

• US 20060016960A1
• Filed: 02/22/2005
• Published: 01/26/2006
• Est. Priority Date: 09/29/1999
• Status: Active Grant

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Color Kinetics Incorporated (Signify N.V.)
• Inventors: Lys, Ihor, Morgan, Frederick M.
• Granted Patent: US 7,482,565 B2
• Time in Patent Office: Days
• 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

1-24. -24. (canceled)

25. An illumination device comprising:

a plurality of differently colored LED illumination sources configured to generate an additive mixture of colored light;

at least one photosensor for obtaining at least one output measurement of radiation generated by at least some of the LED sources;

a processor in communication with the at least one photosensor for making a comparison of the at least one output measurement and at least one reference value and formulating at least one calibration value based on the comparison; and

a memory mechanism coupled to the processor and on which the resulting at least one calibration value is stored.

26. A device as set forth in claim 25, further including a display on which parameters regarding light output from at least some of the LED sources may be provided to inform a user of a status of the light output.

27. A device as set forth in claim 25, further including an interface to permit a user to vary light output parameters.

28. A device as set forth in claim 25, wherein the at least one reference value includes a plurality of pre-programmed reference values that are stored on the memory mechanism.

29. A device as set forth in claim 28, wherein the plurality of pre-programmed reference values are stored on the memory mechanism as a table of fixed values representative of respective types of the plurality of LED sources.

36. The illumination device of claim 25, wherein:

the plurality of LED sources includes;

at least one first light source adapted to output first radiation having a first color; and

at least one second light source adapted to output second radiation having a second color different from the first color;

the processor is configured to receive at least first and second lighting commands and, based on the at least one calibration value, control the at least one first light source so as to output the first radiation at a first calibrated intensity that substantially corresponds in a predetermined manner to the first lighting command, the processor further configured to control the at least one second light source so as to output the second radiation at a second calibrated intensity that substantially corresponds in a predetermined manner to the second lighting command.

37. The illumination device of claim 36, wherein the at least one first light source and the at least one second light source are arranged with respect to each other so as to mix the first and second radiation having the respective first and second calibrated intensities to produce a single calibrated color at a given time.

38. The illumination device of claim 36, wherein the processor is configured as an addressable processor to receive the at least first and second lighting commands via a network connection based on an address of the processor.

39. The illumination device of claim 37, wherein the at least first and second lighting commands are provided to the processor such that the single calibrated color produced by mixing the first and second radiation having the respective first and second calibrated intensities is a calibrated substantially white color.

40. The illumination device of claim 36, wherein the processor is configured to control the at least one first light source and the at least one second light source using a pulse width modulation technique, and wherein the at least first and second commands represent respective duty cycles of pulse width modulation signals used to control the at least one first light source and the at least one second light source.

41. The illumination device of claim 36, further comprising an at least partially transparent housing that at least partially encloses the at least one first light source and the at least one second light source so as to mix the first and second radiation.

42. The illumination device of claim 40, wherein the processor is configured as an addressable processor to receive the at least first and second lighting commands via a network connection based on an address of the processor.

43. The illumination device of claim 36, wherein the at least one calibration value includes a plurality of calibration values, and wherein the processor is configured to:

apply at least one first calibration value to the first lighting command to control the at least one first light source to output the first calibrated intensity; and

apply at least one second calibration value to the second lighting command to control the at least one second light source to output the second calibrated intensity.

44. The illumination device of claim 43, wherein the memory mechanism is configured to store at least the at least one first calibration value and the at least one second calibration value.

45. The illumination device of claim 43, wherein the memory mechanism includes:

a first memory integrated with the at least one first light source, the first memory storing the at least one first calibration value; and

a second memory integrated with the at least one second light source, the second memory storing the at least one second calibration value.

46. The illumination device of claim 43, wherein the at least one photosensor is adapted to measure the first radiation and the second radiation, wherein the at least one reference value includes a plurality of reference values, and wherein the processor is configured to:

determine the at least one first calibration value by comparing the measured first radiation to at least one first reference value; and

determine the at least one second calibration value by comparing the measured second radiation to at least one second reference value.

47. The illumination device of claim 46, further comprising a housing to enclose at least the at least one photosensor, the at least one first light source, and the at least one second light source.

48. The illumination device of claim 46, wherein the at least first and second lighting commands are provided to the processor such that a single calibrated color produced by mixing the first and second radiation having the respective first and second calibrated intensities is a calibrated substantially white color.

49. The illumination device of claim 48, wherein the processor is configured to control the at least one first light source and the at least one second light source using a pulse width modulation technique, wherein the at least first and second commands represent respective duty cycles of pulse width modulation signals used to control the at least one first light source and the at least one second light source, and wherein the processor is configured to apply the at least one first and second calibration values to the at least first and second commands so as to adjust the respective duty cycles of the pulse width modulated signals.

50. The illumination device of claim 49, wherein the processor is configured as an addressable processor to receive the at least first and second lighting commands via a network connection based on an address of the processor.

51. The illumination device of claim 36, wherein the first lighting command includes a first reference signal, and wherein the processor is configured to determine at least one first calibration value for the at least one first light source such that the at least one first light source outputs the first radiation at a first reference intensity when the first lighting command is the first reference signal.

52. The illumination device of claim 51, wherein the at least one photosensor is adapted to measure at least the first radiation, and wherein the processor is configured to determine the at least one first calibration value by:

applying the first reference signal to the at least one first light source;

monitoring the measured first radiation from the at least one photosensor;

making a comparison of the measured first radiation and at least one first reference value; and

determining the at least one first calibration value based on the comparison.

53. The illumination device of claim 52, further comprising a housing to enclose at least the at least one photosensor, the at least one first light source, and the at least one second light source.

54. The illumination device of claim 51, wherein the processor is configured to apply the at least one first calibration value to at least one subsequent first lighting command to control the at least one first light source to output the first calibrated intensity.

55. The illumination device of claim 54, wherein the second lighting command includes a second reference signal, and wherein the processor is configured to determine at least one second calibration value for the at least one second light source such that the at least one second light source outputs the second radiation at a second reference intensity when the second lighting command is the second reference signal.

56. The illumination device of claim 55, wherein the at least one photosensor is adapted to measure at least the second radiation, and wherein the processor is configured to determine the at least one second calibration value by:

applying the second reference signal to the at least one second light source;

monitoring the measured second radiation from the at least one photosensor;

making a comparison of the measured second radiation and at least one second reference value; and

determining the at least one second calibration value based on the comparison.

57. The illumination device of claim 56, further comprising a housing to enclose at least the at least one photosensor, the at least one first light source, and the at least one second light source.

58. The illumination device of claim 55, wherein the memory mechanism is configured to store at least the at least one first calibration value and the at least one second calibration value.

59. The illumination device of claim 55, wherein the processor is configured to apply the at least one second calibration value to at least one subsequent second lighting command to control the at least one second light source to output the second calibrated intensity.

60. The illumination device of claim 55, wherein the at least first and second lighting commands are provided to the processor such that a single calibrated color produced by mixing the first and second radiation having the respective first and second calibrated intensities is a calibrated substantially white color.

61. The illumination device of claim 60, further comprising a housing to enclose at least the at least one photosensor, the at least one first light source, and the at least one second light source.

82. The illumination device of claim 25, wherein the processor includes calibration means for adjusting the light output of at least some LED sources of the plurality of LED sources, based on the at least one calibration value, such that the additive mixture of colored light has a calibrated color.

83. The illumination device of claim 82, wherein the additive mixture of colored light is a substantially white light, and wherein the calibration means is configured to adjust the light output of at least some LED sources of the plurality of LED sources, based on the at least one calibration value, such that the additive mixture of colored light has a calibrated substantially white color.

84. The illumination device of claim 82, wherein the calibration means includes means for compensating for perceptible differences in light output between similar illumination devices.

85. The illumination device of claim 82, wherein the calibration means includes means for scaling the light output of at least some LED sources of the plurality of LED sources so as to produce the calibrated color.

86. The illumination device of claim 82, wherein the calibration means includes means for adjusting commands sent to at least some LED sources of the plurality of LED sources, based on the at least one calibration value, so as to produce the calibrated color.

87. The illumination device of claim 86, wherein the means for adjusting commands includes means for applying the at least one calibration value to at least one command sent to at least some LED sources of the plurality of LED sources.

88. The illumination device of claim 87, wherein the processor is configured to control the plurality of LED sources via a plurality of pulse width modulated signals, wherein the at least one command relates to at least one parameter of at least one pulse width modulated signal of the plurality of pulse width modulated signals, and wherein the processor is configured to apply the at least one calibration value to the at least one command so as to adjust the at least one parameter of the at least one pulse width modulated signal.

89. The illumination device of claim 88, wherein the at least one parameter includes a duty cycle of the at least one pulse width modulated signal, and wherein the processor is configured to apply the at least one calibration value to the at least one command so as to adjust the duty cycle of the at least one pulse width modulated signal.

90. The illumination device of claim 89, wherein:

the processor is configured as an addressable processor to be coupled to a network connection, the processor further being configured to receive the at least one command from the network connection based at least in part on an address of the processor.

91. The illumination device of claim 90, wherein the at least one command is communicated over the network connection using a DMX protocol, and wherein the processor is configured to receive the at least one command using the DMX protocol and to apply the at least one calibration value to the at least one command based at least in part on the DMX protocol.

92. The illumination device of claim 82, wherein the at least one reference value is based on at least one measurement of an ambient lighting condition.

93. The illumination device of claim 92, wherein the calibration means is configured to adjust the light output of at least some LED sources of the plurality of LED sources, based on the at least one calibration value, such that the additive mixture of colored light approximates the ambient lighting condition.

94. The illumination device of claim 93, wherein the additive mixture of colored light is a substantially white light, and wherein the calibration means is configured to adjust the light output of at least some LED sources of the plurality of LED sources, based on the at least one calibration value, such that the additive mixture of colored light has a calibrated substantially white color.

95. The illumination device of claim 84, wherein the illumination device is configured to be placed in a lighting network including at least one other illumination device, and wherein the processor is configured to adjust at least one first illumination property of the illumination device so that it is similar to at least one second illumination property of the at least one other illumination device of the lighting network.

96. The illumination device of claim 95, wherein the processor is configured to adjust the at least one first illumination property based at least in part on at least one of an age of the at least one other illumination device, a manufacturing date of the at least one other illumination device, and at least one measured illumination condition of the at least one other illumination device.

30. A method for calibrating light output by at least one light-emitting diode (LED), the method comprising acts of:

generating light output from the at least one LED;

obtaining at least one output measurement for the light output generated by the at least one LED;

comparing the at least one output measurement to at least one reference value;

formulating at least one calibration value based on the act of comparing;

storing the at least one calibration value in memory;

recalling the at least one calibration value from the memory during a subsequent generation of light output; and

applying the at least one calibration value to the at least one LED such that the at least one calibration value permits the subsequent light output to have a calibrated intensity.

31. A method as set forth in claim 30, wherein the step of comparing includes assigning a relative value to the output measurement, such that the relative value may be used in adjusting the output measurement.

32. A method as set forth in claim 31, wherein the step of formulating includes scaling the light output, such that the relative value approximates the reference value to permit generation of uniform light output by the LED.

33. A method as set forth in claim 30, wherein the step of formulating permits adjustment of intensity output by the LED.

34. A method as set forth in claim 30, wherein the step of formulating permits adjustment of color output by the LED.

35. A method as set forth in claim 34, wherein the calibration of color output by the LED can be used to provide a desired overall hue or whiteness in a multiple LED environment.

62. The method of claim 30, wherein the act of applying comprises acts of:

a) generating first radiation from at least one first LED in response to a first lighting command, the first radiation having a first color;

b) generating second radiation from at least one second LED in response to a second lighting command, the second radiation having a second color different from the first color;

c) processing the first lighting command, based on the at least one calibration value, such that the generated first radiation has a first calibrated intensity that substantially corresponds in a predetermined manner to the first lighting command; and

d) processing the second lighting command, based on the at least one calibration value, such that the generated second radiation has a second calibrated intensity that substantially corresponds in a predetermined manner to the second lighting command.

63. The method of claim 62, further including an act of:

e) mixing the first and second radiation having the respective first and second calibrated intensities to produce a single calibrated color at a given time.

64. The method of claim 62, further including an act of:

receiving the at least first and second lighting commands via a network connection based on at least one network address.

65. The method of claim 63, further comprising an act of:

providing the at least first and second lighting commands such that the single calibrated color produced in the act e) is a calibrated substantially white color.

66. The method of claim 62, wherein the acts a) and b) include an act of controlling the at least one first LED and the at least one second LED using a pulse width modulation technique, wherein the at least first and second commands represent respective duty cycles of pulse width modulation signals used to control the at least one first LED and the at least one second LED.

67. The method of claim 63, wherein the act e) comprises an act of:

passing the first and second radiation through an at least partially transparent material so as to mix the first and second radiation.

68. The method of claim 62, wherein:

the act c) includes an act of applying at least one first calibration value to the first lighting command to provide the first calibrated intensity; and

the act d) includes an act of applying at least one second calibration value to the second lighting command to provide the second calibrated intensity.

69. The method of claim 68, wherein the act of storing comprises an act of:

storing at least the at least one first calibration value and the at least one second calibration value in the memory.

70. The method of claim 68, wherein:

the act of obtaining at least one output measurement for the light output generated by the at least one LED includes an act of measuring the first radiation and the second radiation; and

the act of formulating at least one calibration value includes acts of;

determining the at least one first calibration value by comparing the measured first radiation to at least one first reference value; and

determining the at least one second calibration value by comparing the measured second radiation to at least one second reference value.

71. The method of claim 70, further comprising an act of:

providing the at least first and second lighting commands so as to generate a calibrated substantially white color.

72. The method of claim 62, wherein the first lighting command includes a first reference signal, and wherein the act c) includes an act of:

c1) determining at least one first calibration value such that the first radiation is generated at a first reference intensity when the first lighting command is the first reference signal.

73. The method of claim 72, wherein:

the act of generating light output from the at least one LED includes an act of asserting the first reference signal;

the act of obtaining at least one output measurement for the light output generated by the at least one LED includes an act of measuring the first radiation generated in response to the first reference signal;

the act of comparing the at least one output measurement to at least one reference value includes an act of making a comparison of the measured first radiation and at least one first reference value; and

the act of formulating at least one calibration value includes an act of determining the at least one first calibration value based on the comparison.

74. The method of claim 72, wherein the act of storing comprises an act of:

storing at least the at least one first calibration value in the memory.

75. The method of claim 72, wherein the act c) further includes an act of:

c2) applying the at least one first calibration value to at least one subsequent first lighting command to provide the first calibrated intensity.

76. The method of claim 75, wherein the second lighting command includes a second reference signal, and wherein the act d) includes an act of:

d1) determining at least one second calibration value such that the second radiation is generated at a second reference intensity when the second lighting command is the second reference signal.

77. The method of claim 76, wherein:

the act of generating light output from the at least one LED includes an act of asserting the second reference signal;

the act of obtaining at least one output measurement for the light output generated by the at least one LED includes an act of measuring the second radiation generated in response to the second reference signal;

the act of comparing the at least one output measurement to at least one reference value includes an act of making a comparison of the measured second radiation and at least one second reference value; and

the act of formulating at least one calibration value includes an act of determining the at least one second calibration value based on the comparison.

78. The method of claim 76, wherein the act of storing comprises an act of:

storing at least the at least one second calibration value in the memory.

79. The method of claim 76, wherein the act d) further includes an act of:

d2) applying the at least one second calibration value to at least one subsequent second lighting command to provide the second calibrated intensity.

80. The method of claim 79, further comprising an act of:

providing the at least first and second lighting commands so as to generate a calibrated substantially white color.

81. The method of claim 79, wherein:

the acts a) and b) include an act of controlling the at least one first LED and the at least one second LED using a pulse width modulation technique, wherein the at least first and second commands represent respective duty cycles of pulse width modulation signals used to control the at least one first LED and the at least one second LED; and

the acts c) and d) include an act of applying the at least one first and second calibration values to the at least first and second commands so as to adjust the respective duty cycles of the pulse width modulated signals.