Method for controlling the luminous flux spectrum of a lighting fixture
First Claim
1. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum subject to substantial initial variability, wherein the lighting fixture lacks a filter for substantially limiting the bandwidth of light emitted by any of the plurality of groups of light-emitting devices, the method comprising:
- calibrating each of the plurality of groups of light-emitting device by measuring the initial flux magnitude or light emitted by the group, at a prescribed test temperature, in response to a predetermined electrical power input; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum.
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Abstract
A method is disclosed for controlling a lighting fixture of a kind having individually colored light sources, e.g., LEDs, that emit light having a distinct luminous flux spectrum that varies in its initial spectral composition, that varies with temperature, and that degrades over time. The method controls such fixture so that it projects light having a predetermined desired flux spectrum despite variations in initial spectral characteristics, despite variations in temperature, and despite flux degradations over time.
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Citations
23 Claims
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1. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum subject to substantial initial variability, wherein the lighting fixture lacks a filter for substantially limiting the bandwidth of light emitted by any of the plurality of groups of light-emitting devices, the method comprising:
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calibrating each of the plurality of groups of light-emitting device by measuring the initial flux magnitude or light emitted by the group, at a prescribed test temperature, in response to a predetermined electrical power input; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum. - View Dependent Claims (2, 3, 4)
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5. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum subject to substantial initial variability, the method comprising:
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calibrating each of the plurality of groups of light-emitting device, by measuring the spectral distribution of light emitted by the group in response to a predetermined electrical power input, wherein the step of calibrating includes measuring the initial magnitude, the initial peak wavelength, and the initial spectral half-width of flux emitted by each of the plurality of groups of light-emitting devices at a prescribed test temperature, in response to a predetermined electrical power input; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum.
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6. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum subject to substantial initial variability, wherein the method controls the lighting fixture such that its emitted light has a composite luminous flux spectrum emulating the luminous flux spectrum of a known light source, with or without a filter, the method comprising:
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calibrating each of the plurality of groups of light-emitting devices by measuring the flux magnitude of light emitted by the group in response to a predetermined electrical power input; and
supplying a prescribed amount of electrical power to each of the light-emitting devices in each of the plurality of groups of devices such that the plurality of groups of devices cooperate to emit light having a composite luminous flux spectrum that has a minimum normalized mean deviation across the visible spectrum relative to the luminous flux spectrum of a known light source to be emulated, with or without an associated color filter.
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7. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum subject to substantial initial variability, the method comprising:
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calibrating each of the plurality of groups of light-emitting devices by measuring the initial flux magnitude of light emitted by the group, at a prescribed test temperature, in response to a predetermined electrical power input; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum;
wherein the distinct luminous flux spectrum of light emitted by each of the plurality of groups of light-emitting devices varies with temperature;
wherein the method further comprises determining the temperature of each of the light-emitting devices in each of the plurality of groups of devices;
and wherein the prescribed amount of electrical power that is supplied to the light-emitting devices in the step of supplying is selected, in part, based on the temperature determination for each device. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum having a magnitude and a peak wavelength that vary with temperature, the method comprising:
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determining the temperatures or the light-emitting devices in each of the plurality of groups of devices;
determining the spectral distribution of the flux emitted by each of the plurality of groups of light-emitting devices based on the temperature determinations, including a preliminary step of measuring the magnitude and peak wavelength of flux emitted by each of the plurality of groups of devices at a plurality of test temperatures; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a composite luminous flux spectrum that has a minimum normalized mean deviation across the visible spectrum relative to the luminous flux spectrum of a known light source to be emulated, with or without a color filter. - View Dependent Claims (15, 16, 17)
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18. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices are mounted on a heat sink, each group emitting light having a distinct luminous flux spectrum that varies with temperature, the method comprising:
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determining the temperatures of the light-emitting devices in each of the plurality of groups of devices;
determining the spectral distribution of the flux emitted by each of the plurality of groups of light-emitting devices based on the temperature determinations; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum;
wherein the step of determining the temperature of each of the light-emitting devices includes measuring ambient temperature, and calculating the temperature of each of the light-emitting devices based on the amount of electrical power being supplied to such device, the amount of flux emitted by the device, the thermal resistance between such device and the heat sink, the total amount of electrical power being supplied to all of such devices less the total amount of flux emitted by the devices, the thermal resistance between the heat sink and the surrounding air, and the measured ambient temperature.
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19. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum that varies with temperature, the method comprising:
- determining the temperatures of the light-emitting devices in each of the plurality of groups of devices;
determining the spectral distribution of the flux emitted by each of the plurality of groups of light-emitting devices based on the temperature determinations and also based on a factor relating to flux degradation over time for such devices; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum. - View Dependent Claims (20)
- determining the temperatures of the light-emitting devices in each of the plurality of groups of devices;
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21. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum that varies with temperature, the method comprising:
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determining the temperatures of the light-emitting devices in each of the plurality of groups of devices;
determining the spectral distribution of the flux emitted by each of the plurality of groups of light-emitting devices based on the temperature determinations; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum;
wherein the step of supplying includes supplying an amount of electrical power to each of the light-emitting devices in each of the plurality of groups of devices such that the plurality of groups of devices cooperate to emit light having a composite luminous flux spectrum that has a minimum normalized mean deviation across the visible spectrum relative to the luminous flux spectrum of a known light source to be emulated, with or without a color filter.
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22. A method for controlling the luminous flux spectrum of light produced by a lighting fixture of a kind incorporating a plurality of groups of light-emitting devices, each group emitting light having a distinct luminous flux spectrum subject to degradation over time, the method comprising:
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establishing a time-based degradation factor for each of the plurality of groups of light-emitting devices; and
supplying a prescribed amount of electrical power to the light-emitting devices in each of the plurality of groups of devices, wherein the prescribed amount of electrical power is selected, in part, based on the time-based degradation factor established for each of the groups of devices, such that the groups of devices cooperate to emit light having a desired composite luminous flux spectrum throughout the lighting fixture'"'"'s lifetime. - View Dependent Claims (23)
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Specification