Inference From Lumen Degradation Data Under Wiener Diffusion Process

• Published in: IEEE transactions on reliability Vol. 61; no. 3; pp. 710 - 718
• Main Authors: Tsai, Tzong-Ru, Lin, Chin-Wei, Sung, Yi-Ling, Chou, Pei-Ting, Chen, Chiu-Ling, Lio, Yuhlong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2012; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Approximation; Arrhenius law model; Cumulative damage; Degradation; Diffusion; draft parameter; exponential law model; Inequalities; Light emitting diodes; Load modeling; Loading; Lumens; Maximum likelihood estimation; power law model; Reliability; step-stress loading method; Stress; Stresses
• ISSN: 0018-9529; 1558-1721
• DOI: 10.1109/TR.2012.2207533

The lumen degradation of light emitting diodes subject to increasing stress loading is investigated by using a cumulative damage model. The cumulative damage process is taken as a Wiener diffusion process with a drift which depends on two stress loadings. General statistical inferences on the parameters and percentiles of the light emitting diode lifetime distribution are presented based on the cumulative damage measurements, collected from a two-variable constant-stress loading accelerated degradation test. Approximate lower s -confidence bounds of the light emitting diode lighting lifetime percentiles are given using the Fisher information of the maximum-likelihood estimators, and Bonferroni's inequality. The application of the proposed method is illustrated by a lumen cumulative damage data set of high power light emitting diodes.