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US 8,013,281 B2Granted
Systems and methods for calibrating light output by light-emitting diodes
AssigneePhilips Solid-State Lighting Solutions, Inc.
InventorsFrederick M. Morgan, Ihor A. Lys
Life of this patent
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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.
Claims15
An LED-based lighting 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;
- a memory for storing at least one first calibration value and at least one second calibration value, wherein the first calibration value represents a difference between a peak value of the first LED and a reference value established for the first LED, and wherein the second calibration value represents a difference between a peak value of the second LED and a reference value established for the second LED;
- and
- at least one controller to receive at least first and second lighting commands, the at least one controller configured to:
- control the at least one first LED and the at least one second LED using a pulse width modulation technique, the at least first and second lighting commands representing respective duty cycles of pulse width modulation signals used to control the at least one first LED and the at least one second LED,
- apply the at least one first calibration value to the first lighting command to control the at least one first LED so as to output the first radiation at a first calibrated intensity that substantially corresponds in a predetermined manner to the first lighting command, and
- apply the at least one second calibration value to the second lighting command to control the at least one second LED so as to output the second radiation at a second calibrated intensity that substantially corresponds in a predetermined manner to the second lighting command.
5 more elements
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) providing at least first and second lighting commands, the at least first and second lighting commands representing respective duty cycles of pulse width modulation signals for controlling the at least one first LED and the at least one second LED;
- D) retrieving from at least one memory at least one first calibration value and at least one second calibration value, wherein the first calibration value represents a difference between a peak value of the first LED and a reference value established for the first LED, and wherein the second calibration value represents a difference between a peak value of the second LED and a reference value established for the second LED;
- E) applying the at least one first calibration value to the first lighting command to control the at least one first LED so as to output the first radiation at a first calibrated intensity that substantially corresponds in a predetermined manner to the first lighting command;
- and
- F) applying the at least one second calibration value to the second lighting command to control the at least one second LED so as to output the second radiation at a second calibrated intensity that substantially corresponds in a predetermined manner to the second lighting command.
4 more elements
Dependencies are inferred from the claim text.