Measurement Of Two-dimensional Static And Transient Junction Temperature Distribution Of LEDs By Reflected Light Method

LED(Light-Emitting Diode)based solid-state lighting technology is an emerging high-tech industry with the most development prospects in the 21st century.However,LEDs still have many challenges in terms of thermal characteristics,so exploring reliable LED junction temperature testing methods has become a hot topic in the LED field.The current LED junction temperature testing methods are mainly divided into contact type and non-contact type.The former easily affects the working state of the LED,and the latter can only obtain the average temperature in a certain area.According to such difficulties,this paper proposes a two-dimensional LED junction temperature detection technology based on micro-spectral reflected light method.Furthermore,since most of the current studies only consider the macroscopic and static-state properties of LEDs in depth,but have little involvement in the study of their microscopic and transient characteristics.Therefore,this paper builds a micro highspeed camera system,which can study the transient photoelectric performance and junction temperature characteristics of LED.The main works are presented as follows:1.A two-dimensional LED junction temperature detection technology based on micro-hyperspectral reflected light method is proposed.With the advantages of both high spectral resolution and high spatial resolution,combined with the linear relationship between the relative intensity of reflected light and temperature change of the LED under test,the two-dimensional temperature sensitivity coefficient between the reflected light of different LED chips is calibrated and smoothened processed.2.Analysis and comparison of micro static two-dimensional junction temperature test results are carried out.The two-dimensional temperature distribution of LEDs with experimental conditions are obtained by fitting.Compared with the thermocouple and infrared thermal-imaging methods,the error is small,and the spatial resolution of the testing results is at least an order of magnitude higher than that of the thermal-imaging method.3.A two-dimensional LED junction temperature detection technology based on micro high-speed imaging is proposed.A micro high-speed camera system can be built to capture the micro-transient photothermal characteristics of the LED under test.Compared with infrared thermal-imaging method,the temporal resolution is improved by at least an order of magnitude.4.Analysis and comparison of micro transient two-dimensional junction temperature test results are carried out.We calculate the micro-transient twodimensional junction temperature changes of the LED under test of different rising edge current conditions.The final experimental results are compared with those of the infrared thermal-imaging method,which verified the temperature distribution trend of the chip.5.Develop data processing and analysis software based on Python.A large-scale data preprocessing and result analysis software has been developed for the needs of experimental processing,which simplifies the data processing.