Active Area Temperature Measurement of Medium-Power LEDs by Dynamics Changes in Forward Voltage during Current Heating and Cooling

Abstract

The most common non-destructive methods of measuring the temperature of the active area of light emitting diodes (LEDs) are briefly analysed and their disadvantages are pointed out. Measurements of the temperature of the active area of medium-power LEDs by the dynamics of change in the direct voltage during heating by currents of different densities and in the process of cooling in the mode of flow of small, so-called measuring current, which not cause heating of LEDs, are presented. An electrical scheme realising the used method is given. The results of measurements show that the thermal resistance of LED, determined by the results of measuring the temperature of the active area by the proposed method, is greater than the reference value. The comparison of the results of temperature measurements using traditional methods of analysing the radiation spectra of LEDs and the temperature dependence of direct voltage is carried out.