A Research On Integrated Optical & Thermal Measurement System For High Power LEDs

This paper will focus on research of test method and test system about light emitted diode as the rapid development of optoelectronic device demands the novel test technology,including the principal,the method,the steps and the implement of test system of parameter testing,such as electronic performance,thermal performance parameters of high power LED,spectral and photometric parameters of LED.The main research in this paper is the amendatory measure method and the implement of test system.The system designed which is base on USB2.0 and RS232 interface is integrated measure system of spectral,photometric,thermal and electrical meters for LEDs.It includes module of rapid numerical control electric and voltage current,TE-cooler constant temperature controller, photometric measure channel and additional Spectrometer.The measurement principle and method based on the electrical measurement method for thermal resistance of high power LED.A new method of pulse measurement is presented for reference thermal resistance test base on the electrical measurement method.The proposed approach is Real-Time detection of the voltage variation by pulse while reference thermal resistance measurement,base of it the characteristics of the reference thermal resistance can be more directly and reliability.The method is applied in our system and delightful results are obtained.The experimental results show that the method has the advantages of good stability and exactitude.For the hardware of the system,the EZ-USB FX2(CY7C68013) chip is adopted as the main MCU(micro-controller unit),with it the system can actualize high speed communication with the PC(personal computer) by USB.The display panel of the system which controlled by AT89S52 communication with the main MCU via RS-232 port.The rapid numerical control electric and voltage current,TE-cooler constant temperature controller,signal transform and measure circuit are designed.A high-speed 16bit high speed A/D converter is used to ensure the precision and respondent rate,16 bit high speed D/A converter is used to ensure the current precision and switch rate. The system software is comprised by the MCU program and the PC program.The system can both controlled by the PC and the display panel.The thermal resistance test diagram base of pulse measurement method and temperature control diagram base of PID also present in this paper.At last,the measurement uncertainties of the system are analyzed.