Investigation of color shift of LEDs-based lighting products

LED has the potential to revolutionize the lighting industry with their long lifetime and high efficacy. However, the long lifetime claimed by the manufacturers is often based solely on the estimated lumen depreciation and this is insufficient since the color shift of LEDs products is another important issue that need to be considered for LEDs products in order for them to perform their intended function. It has been shown through DOE's CALIPER program and GATEWAY program that color aging during LED products lifetime can be so extensive that it could be considered as a failure to the end-user. Nevertheless, although performance evaluation based on LED lumen depreciation had been well documented and established, literature on the performance evaluation based on color shift is very limited. This is because the mechanism for color shift is not well understood, nor the measurement / characterization methods. Therefore, an investigation of color aging over lifetime is urgently needed. Therefore, this paper will attempt to address the color shift of the plastic lenses and proposed a model for predicting color shift in LEDs lenses.