A Bipolar-Pulse Voltage Method For Junction Temperature Measurement of Sporadic Current LED

For measuring junction temperature of alternating current light emitting diodes a new method is introduced. New method employs a periodic bipolar voltage pulse signal as input, and utilizes amplitude of corresponding output current as temperature sensitive parameter (TSP), of which linear temperature dependence is proven in a prior experiment. Basis of TSP a device detailed procedure is adopted; First measure thermal resistance of package of ac LED's which further contributes to calculation of junction temperatures under various power inputs. Comparisons between values calculated by using method and those obtained directly from a thermocouple indicate a decent accuracy of former. The proposed system can be quickly assembled with few extra costs, since all components are common in laboratories of electronic institutes. For obtaining junction temperature by measuring electric and optical powers advantages of a specific method benefits from stability of thermal resistance under different driving conditions