Method for detecting junction temperature of chip of LED lamp

The invention discloses a method for detecting the junction temperature of a chip of an LED lamp, which comprises steps of: 1. under the electric current of extremely short pulse as the same as that that of the normal work of the lamp, obtaining the relationship between the positive voltage of the two ends of the lamp and the change of the junction temperature of the chip by controlling the temperature of ambient environment; 2. under the DC normal work of the lamp, obtaining the positive voltage of the two ends of the lamp when achieving the stability of the thermal balance; and 3. substituting the positive voltage data into the relationship obtained in step 1 between the positive voltage of the lamp and the junction temperature of the chip to ensure the work junction temperature of the chip of the lamp under normal working condition. The method can exactly judge the work junction temperature of the chip of the LED lamp under different working currents, and is good for the heat dispersion of the LED lamp, the evaluation of the service life and the optimization design of the lamp.