LED lighting system
First Claim
1. A method of compensating for color variation due to temperature change in an LED based lighting system having at least one LED array, wherein same color LEDs are electrically connected to form LED channels, the method comprising:
- determining a pulse width needed for at least one LED channel to achieve a predetermined target color at at least a first and a second temperature;
calculating a pulse width correction factor for the at least one LED channel based on the pulse width needed to achieve the predetermined target color at the at least first and second temperatures;
correcting the pulse width for the at least one LED channel using the pulse width correction factor to achieve the predetermined target color.
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Accused Products
Abstract
Method and system are disclosed for compensating for color variations due to thermal differences in LED based lighting systems. The method and system involves characterizing the LEDs to determine what PWM (pulse-width modulation) is needed at various operating temperatures to achieve a desired resultant color. The characterization data is then stored in the microprocessor either in the form of a correction factor or as actual data. When an operating temperature that is different from a calibration temperature is detected, the characterization data is used to adjust the PWM of the LEDs to restore the LEDs to the desired resultant color.
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Citations
29 Claims
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1. A method of compensating for color variation due to temperature change in an LED based lighting system having at least one LED array, wherein same color LEDs are electrically connected to form LED channels, the method comprising:
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determining a pulse width needed for at least one LED channel to achieve a predetermined target color at at least a first and a second temperature;
calculating a pulse width correction factor for the at least one LED channel based on the pulse width needed to achieve the predetermined target color at the at least first and second temperatures;
correcting the pulse width for the at least one LED channel using the pulse width correction factor to achieve the predetermined target color. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An LED based lighting system with thermal compensation capability, comprising:
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at least one LED array having same color LEDs electrically connected to form LED channels;
a microprocessor connected to and independently controlling each LED channel of the LED array to achieve a desired resultant color;
a temperature sensor connected to the microprocessor for detecting an operating temperature of the at least one LED array; and
an algorithm stored on the microprocessor and configured to cause the microprocessor to compensate for differences in the operating temperature of the at least one LED array. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of compensating for color variation due to temperature change in an LED based lighting system having at least one LED array, wherein same color LEDs are electrically connected to form LED channels, the method comprising:
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deriving a temperature compensation curve for the LED array;
calculating a correction factor for at least one LED channel based on temperature compensation curve; and
compensating for differences in an operating temperature for the LED array. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A method of calibrating an LED based lighting system having at least one LED array, wherein same color LEDs are electrically connected to form LED channels, the method comprising:
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(a) stabilizing the LED channels;
(b) maximizing an intensity level of one of the LED channels;
(c) adjusting an intensity level of at least one other LED channel until a predetermined target color is achieved;
(d) waiting a predetermined amount of time;
(e) readjusting the intensity level of the at least one other LED channel until the predetermined target color is achieved again; and
(f) storing the intensity levels of the LED channels as calibration intensity levels. - View Dependent Claims (27, 28, 29)
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Specification