A Weibull–lognormal-based life prediction model for LED light with four groups of ADTs

Abstract

Four groups of accelerated degradation tests of light-emitting diode (LED) lights under constant current stresses were carried out with the goal of precisely and rapidly obtaining the conventional life of LED lights. Three-parameter Weibull function and right approximation method were used to fit the test data of the luminance degradation with time of samples under different stresses, and the pseudo-failure time of each sample was calculated according to the failure criteria. Then combined with lognormal distribution and least square method, the life distribution of LED lights under each stress was determined, and the life of LED lights under conventional stress was extrapolated by inverse power law. The results show that the obtained luminance degradation data can reflect the decay trend of LED lights preferably and obey the three-parameter Weibull function, the lognormal distribution has a good fitting effect on the failure time distribution of LED lights, and the conventional life predicted by the model combined with Weibull function and lognormal distribution has a high accuracy. Manufacturers and researchers of LED lights can benefit from theoretical foundation and technical reference offered by the life tests of LED lights and the established life prediction model.