Study Of The Aging Mechanism And Aging Model Of The High-Power White LED

The high-power white LEDs of the aging mechanism and life calculation were studied in the thesis. The experimental and theoretic results are helpful to the application of high-power LEDs and replace the traditional lights.The main contents are listed as follows:1.There are two kinds of current and thermal stress in the LEDs aging under current experiment. So the single Eyring model was amended to be the generalized Eyring model. The theoretic result can fit the experiment data and verify the correctness of the generalized Eyring model. Thus, the lifetime with standard current was accurately calculated according to the generalized Eyring model.2. The current accelerated aging experiment was used to investigate the luminous attenuation and aging time of the high-power white LEDs. The slow luminous attenuation was found at the early stage. The mechanism of the attenuation was discussed from the chip, the expoy and the phosphor. The slow attenuation at the early stage was mainly attributed to the aging of chips. In order to better study the influence of the luminous attenuation by the aging of LED chips, the LED heat sink had been removed during the current stress.Two kinds of luminous attenuation process were found:the slow attenuation at the early stage and the fast attenuation at the late stage. The two kinds of attenuation were mainly attributed to the aging of chips. The mechanism of two kinds of the attenuation was also discussed.3. According to the automatic control system based on open-loop control, the high-power LED aging system model was proposed. The transfer function G(s) of the system dynamics model was defined as G vi(s) and G vj(s). The transfer function G vi(s) and G vj(s) were analyzed. The relation between the G vi(s) and the aging time could be use to express the aging characteristics of LED chips. G vj(s) could be used to express the relation between the voltage and the temperature.