Study on the chromaticity of LED lamps given by online test during accelerated aging under thermal stress

In this paper, the changes in chromaticity of LED lamps given by online test during accelerated aging under thermal stress were studied. Firstly, two online accelerated aging tests of a same type of lamps were conducted, with one test at the temperature of 60 ℃ and another at the temperature of 80 ℃. With the experimental data, the activation energy was obtained through the Arrhenius model, and then the accelerated aging time at the temperature of 80 ℃ equivalent to 6000 h aging at temperature of 25 ℃ was calculated. Secondly, the correlated color temperature (CCT) and color shift during accelerated aging test at the temperature of 80 ℃ were measured by both online test and offline test. It was shown that the increment amounts of CCT and color shift given by the online test were both about 20% higher than that given by the offline test. The t test and t' test were used to verify the difference in chromaticity, which shows that the difference is of statistical significance. Therefore, the change of CCT and color shift given by the online test during accelerated aging can be used to judge the failure of lamps with some revision of the current criterions.