Illumination device and method for calibrating and controlling an illumination device comprising a phosphor converted LED
First Claim
1. A method for calibrating a phosphor converted LED, which is included within an illumination device along with a first photodetector and a second photodetector, the method comprising:
- successively applying at least three different drive currents to the phosphor converted LED to produce illumination at different levels of brightness upon subjecting the phosphor converted LED to a first ambient temperature;
measuring photocurrents induced on the first and second photodetectors by the illumination produced by the phosphor converted LED at each of the at least three different drive currents;
measuring forward voltages that develop across the first and second photodetectors before or after each induced photocurrent is measured; and
storing results of the measuring steps within the illumination device to calibrate the phosphor converted LED at the first ambient temperature.
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Accused Products
Abstract
An illumination device described herein includes at least a phosphor converted LED, which is configured for emitting illumination for the illumination device, a first photodetector and a second photodetector. A spectrum of the illumination emitted from the phosphor converted LED comprises a first portion having a first peak emission wavelength and a second portion having a second peak emission wavelength, which differs from the first peak emission wavelength. The first photodetector has a detection range, which is configured for detecting only the first portion of the spectrum emitted by the phosphor converted LED. The second photodetector has a detection range, which is configured for detecting only the second portion of the spectrum emitted by the phosphor converted LED. Methods are provided herein for calibrating and controlling each portion of the phosphor converted LED spectrum, as if the phosphor converted LED were two separate LEDs.
263 Citations
29 Claims
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1. A method for calibrating a phosphor converted LED, which is included within an illumination device along with a first photodetector and a second photodetector, the method comprising:
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successively applying at least three different drive currents to the phosphor converted LED to produce illumination at different levels of brightness upon subjecting the phosphor converted LED to a first ambient temperature; measuring photocurrents induced on the first and second photodetectors by the illumination produced by the phosphor converted LED at each of the at least three different drive currents; measuring forward voltages that develop across the first and second photodetectors before or after each induced photocurrent is measured; and storing results of the measuring steps within the illumination device to calibrate the phosphor converted LED at the first ambient temperature. - View Dependent Claims (2, 3, 4)
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5. An illumination device, comprising:
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a phosphor converted LED configured for emitting illumination for the illumination device, wherein a spectrum of said illumination comprises a first portion having a first peak emission wavelength and a second portion having a second peak emission wavelength, which differs from the first peak emission wavelength; a first photodetector having a detection range configured for detecting only the first portion of the spectrum emitted by the phosphor converted LED; and a second photodetector having a detection range configured for detecting only the second portion of the spectrum emitted by the phosphor converted LED. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for controlling an illumination device comprising a phosphor converted LED, a first photodetector and a second photodetector, wherein the method comprises:
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applying a drive current to the phosphor converted LED substantially continuously to produce illumination; measuring photocurrents induced on the first and second photodetectors in response to the illumination, which is produced by the phosphor converted LED and received by the first and second photodetectors; measuring forward voltages that develop across the first and second photodetectors before or after the photocurrents are measured by applying a non-operative drive current to each of the first and second photodetectors; determining expected photocurrent values for the phosphor converted LED corresponding to the forward voltages measured across the first and second photodetectors and the drive current currently applied to the phosphor converted LED by applying one or more interpolation techniques to a table of stored calibration values correlating forward voltage and photocurrent to drive current at a plurality of different temperatures; and adjusting the drive current currently applied to the phosphor converted LED if a difference exists between the expected photocurrent values and the measured photocurrents. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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Specification