Lifetime estimation of LED lamp using gamma process model

Article history: Received 17 December 2014 Received in revised form 1 December 2015 Accepted 3 December 2015 Available online 19 December 2015 The data for the lightflux degradation and chromaticity shift of LED lamps exhibits a considerable amount of scatter due to intrinsic and extrinsic factors. In this study, some degradation models, such as the gamma process model, were reviewed in terms of uncertainties associated with the continuous, gradual, and monotonic nature of degradation. Statistically varying light flux degradation and chromaticity shift data in a test report from Lumileds were used as an example to demonstrate the use of the gamma processmodel. Thismodel can describe the condition and lifetime as statistical distribution curves whose shapes vary with operation time. The service life was estimated as a median value, while the warranty life was estimated as a B2.5 life for lumen degradation and B25 life for chromaticity shift from consideration of the optimal replacement life and percentile life. © 2015 Elsevier Ltd. All rights reserved.