Research And Application Of LED Parameter Measurement And Quality Control

LED industrial chain is mainly composed of chip research, packaging industry and its application. The measurement of LED Parameter and its quality control are very important for LED packaging industry. For LED application. it is the inevitable trend in the future that the power LEDs is applied to the car lamps. But there are still many technical problems existed in LED packaging industry and its application:how to analyze the key measuring implements in LED measurement system, how to measure accurately LED Parameter on-line, how to control the qualities of LED key Parameter, how to analyze and solve heat dissipation of power LEDs in the car lamps.According to the least square method, the measurement system of LED spectrometer is researched. The measurement process of LED dominant wavelengths and intensities are analyzed by means of the quality control charts. On-line automatic measuring program with high-precision for LED Parameter is designed. Based on ANSYS software, thermal coupling in power LED lamps is analyzed. The main research works are as follows.1. By means of least square method, the coefficients of linear regression equation for the spectrometer phases and peak wavelengths are solved. According to the F-test and t-test, the significance of the linear regression equation is tested and the results verify the linear regression equation reliable and practical. By means of square difference analysis, the measurement capability of the spectrometer is effectively evaluated and the results verify that its measurement capability is stable.2. The measurement process of LED dominant wavelengths is analyzed by means of the quality control chart. The measurement framework of LED dominant wavelengths is designed, and the test process of the colorimetric parameter is analyzed totally. The measurement process of LED dominant wavelengths are analyzed according to Shewhart control chart and the EWMA (Exponentially Weighted Moving Average) control chart, and the correct analysis method for small offset data in the quality control is pointed.3. For the measured data of LED intensities, the smoothed-factor Bayes control method is presented to control the LED quality. The measurement characteristics and methods are analyzed for LED intensities. When LED intensity quality data in the test process are much better than the acceptable quality level, Smoothed-Factor Bayes Control Method can be recommended to avoid good products to be distinguished unqualified products. According to the trend analysis for sample mean values, the error sources in LED intensity test process are analyzed, and the improvement measures are proposed for LED intensity measurement system.4. On-line automatic measurement program for LED Parameter is designed. Total measurement process of LED Parameter is comprehensively analyzed, and based on LabVIEW, the corresponding modules for subprograms are also designed. In order to improve measurement speeds of LED Parameter, the chromaticity diagram is presented to divide it into4different regions according to the slopes monotonic decreasing. And in order to improve its measurement accuracy, the looking-up table method is proposed.5. The three-dimension model of heat-dissipation devices for LED lamps is designed. Based on ANSYS software, the thermal coupling in power LED car lamp is analyzed under four conditions such as non-heat-dissipation device, cooling fan, fin radiator, the device of fin radiator and cooling fan. As important references, the analysis results are very useful for heat dissipating arrangement design in power LED car lamp.