Research On Measurement And Compensation Method Of LED Luminous Degradation

High power ultraviolet light source(UVLED)is widely used in industrial fields such as product curing and UV ink jet printing in industrial 3C automation production line.In the process of using LED light source,there are problems of light attenuation and dimming compensation.In the past,the test parameters of light attenuation are single,especially in the field of UV curing,the problem of light attenuation compensation has not been well solved.In this paper,an on-line LED light decay detection method is proposed to monitor the light decay in the UV curing process,collect and store a large number of test data,and provide the basis for LED light decay compensation and rapid life assessment.Aiming at the problem of light decay of LED light source,this paper firstly studies the microscopic essence of LED luminescence,and analyzes the internal and external factors that affect light decay from three aspects of temperature and humidity of LED working environment,power supply current and packaging materials.At the same time,the changes of photoelectric parameters after light decay are analyzed,which provides a feasible method for subsequent LED light decay test parameters and light decay compensation.Aiming at the problem of optical power density and electric power test in the process of light source decay,this paper adopts the way of current integration to pulse counting,and improves the accuracy of optical power density test by adding the compensation method of light energy loss,and improves the optical signal acquisition filter and the data filter of lower computer,and adds the power correction factor as the improvement measure in the electric power test The measurement error of light source electric power is effectively reduced.In the aspect of LED junction temperature and ambient humidity test,the linear relationship between the forward voltage and the junction temperature is fitted by combining the forward voltage method and the least square method,which overcomes the difficulties and untrue problems in the past led internal temperature test.The precision humidity sensor module with its own temperature compensation function is adopted to further improve the relative humidity measurement accuracy.In view of the problem of light failure compensation in different curing situations,two methods of light source power redundancy compensation and BP neural network adaptive dimming compensation are proposed.The former combines Arrhenius model and constant current driver adjusts light according to the preset compensation curve of light failure.The feasibility of the method is verified by the design of double stress accelerated light failure test.According to the principle that the curing effect can be quantified,the test data of LED under normal stress level are studied.The results show that the curing effect error can well meet the existing industrial requirements.Finally,in the aspect of LED life fast evaluation,a relatively fast theoretical calculation method is given.Through the life evaluation of LED under accelerated stress level,the life of light source under normal stress working condition is deduced,which provides a reference scheme for the life evaluation of LED.