Research On Rapid Evaluation Method For The Life Of LED Bulb Lamp

Light-emitting diode(light-emitting diode)is not strange in our daily life in recent years,which has become the fourth generation of lighting source.However,there is a big difference between the theoretical life of several hundred thousand hours and the actual life.There is no uniform standard for LED lighting product life assessment.Therefore,how to quickly and effectively assess the life of LED is a problem needed to address urgently in the field of lighting.This paper proposes a fast evaluation method of life for the LED bulb light.In order to better build the relationship between accelerated stress under different ambient temperature and life of LED lighting product,we need to know the corresponding junction temperature of the LED in different environment temperature and the activation energy,so,also need to test the junction temperature and activation energy.Therefore,the main work of this paper is as follows:(1)The calculation of LED activation energy was carried out.We calculated the activation enery of LED products through the constant temperature accelerated life test to test the luminous flux of the product in two different ambient temperature and use the exponential decay model and Arrhenius mode.As the calculation of activation energy needed to know the junction temperature of the LED,so the LED junction temperature test test was done by the positive junction voltage method to calculate the LED bulb temperature coefficient and the junction temperature at different temperatures at work.(2)The rapid evaluation of the life of white LED bulb was studied and a three-step method ws proposed.According to the inherent properties of LED products,the first step of rough assessment was gived a rough range of LED life;the second step was that life was estimated through the accelerated life test;the third step was gived a corrected value of the life expectancy value of the products in the second stage though fuzzy mathematics tools fully investigating the influence of secondary factors so that we can get a more scientific and reasonable life expectancy.In view of the limitations of the experimental conditions and the lack of contact with the experts to fill out the questionnaire,the first step and the third step was only given a rough program.In the second step,in order to quickly assess the life,we designed to the shortening test time of accelerated life test to assess the life of LED without changing the aging mechanism under the premise of the temperature as the acceleration stress and taked luminous flux attenuation as a failure criterion within 2000h.The test sample was subjected to constant temperature accelerated life test at three different temperatures.The luminous flux at three different temperatures was measured at different times.The lifetime of the product was described by the Weibull distribution and the accelerated life was described by the Alenius model,and then combined with the least squares method to take the measured luminous flux data to do mathematical calculations and statistical analysis,and we finally estimated the lifetime of LED bulb at room temperature(25 ?).Three steps is the innovation of this paper.