LED degradation monitoring using a multi-channel spectral sensor

• Published in: IEEE access Vol. 12; p. 1
• Main Authors: Myland, Paul, Herzog, Alexander, Babilon, Sebastian, Van Driel, Willem D., Khanh, Tran Quoc
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01-01-2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: closed loop; constant light output; constant radiometric output; Current measurement; Degradation; Electric power distribution; Emission analysis; Feedback; Image color analysis; LED degradation; LED maintenance; Light emitting diodes; Lighting control; Monitoring; Optical sensors; Phosphors; Power distribution networks; Radiometry; Sensitivity; Sensor feedback; Sensors; Spectral analysis; Spectral emission; spectral power distribution; spectral reconstruction; spectral sensing; Spectral sensitivity; stable lighting color; Temperature measurement
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2024.3378101

This study explores a novel approach to monitor the spectral emission of LEDs by estimating the spectral power distribution from the spectral sensor responses during an accelerated ageing experiment. Two methods for reconstructing the actual LED spectra from sensor responses are presented and tested, one solely requires sensor datasheet information and the other uses a full spectral characterisation of the sensor's spectral sensitivities. The reconstruction results show that a spectral sensor can provide accurate spectral estimates even after severe LED degradation. Only for an LED that suffered a phosphor crack, affecting its spatial radiation characteristics, limited ability to estimate the true spectral power distribution without prior assumptions about the spectral changes must be reported. Overall, the use of a spectral sensor, even without detailed characterisation of the sensor itself, allows for an accurate monitoring of the true emission of LEDs, with a maximum radiometric error of 0.73 %, a maximum colormetric error of 0.0017Δ u ′ v ′ and a maximum spectral nRMSE error of 0.0097 compared to a spectroradiometric measurement. This advance holds great promise for improving lighting technology, particularly in applications that require constant radiometric output and stable color.