LED luminaire with electronically adjusted color balance
AssigneePhilips Electronics North America Corporation
InventorsMichael D. Pashley, Thomas M. Marshall
Life of this patent
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Abstract
A white light emitting luminaire includes a plurality of LEDs in each of the colors red, green, and blue with a separate power supply for each color and a photodiode arranged to measure the light output of all the LEDs. The light output of each color is measured by an electronic control circuit which turns off the LEDs for the colors not being measured in a sequence of time pulses. The measured light output for each color is compared to a desired output, which may be determined by user inputs, and corrections to the current for each color are made accordingly.
Claims8
A luminaire comprising
- an array of LEDs comprising at least one LED in each of a plurality of colors,
- means for supplying electrical current to said LEDs in each said color, whereby said LEDs in each said color have a light output, and the array has a combined light output when current is supplied to all of the LEDs in the array,
- a photodiode arranged to measure the light outputs of all the LEDs in the array,
- means for selectively turning off the electrical current to said LEDs so that the photodiode measures the light output for each color separately in a sequence of time pulses,
- means for comparing the measured light output for each color to a respective desired light output for each color, and
- means for adjusting the electrical current to the LEDs in each color based on said comparison, whereby a desired combined light output may be achieved using only a single photodiode for the array.
A method for adjusting the color balance of an LED luminaire, said method comprising
- providing an array of LEDs comprising at least one LED in each of a plurality of colors,
- supplying electrical current to said LEDs in each said color, whereby said LEDs in each said color have a light output, and the array has a combined light output when current is supplied to all of the LEDs in the array,
- providing a photodiode arranged to measure the light outputs of all the LEDs in the array,
- sequentially measuring the light outputs of the LEDs for each said color using said photodiode,
- comparing the measured light output for each color to a respective desired light output for each color, and
- adjusting the electrical current to the LEDs in each color based on said comparison.
Dependencies are inferred from the claim text.