dc.description.abstract | Since 2008, the flat display has been claimed for the purposes of light and thin, environment-friendly and energy saving. Because of the mercury, the Cold Cathode Fluorescent Lamp (CCFL) is therefore being substituted gradually for the Light-Emitting Diode (LED) which has the characteristics of power saving, eco-friendly, small, high purity, firm and solid, and long life time. Though the edge-lit LED module can achieve the ultra thin design on the TV LCD panel, there are still many challenges, for example, the adoption of high-efficient LED, the difficulty of the local heat dissipation and the low yield on the large size light-guide manufacturing.
In this thesis, to solve the problem of the local heat dissipation on edge-lit LED backlight module of large sizes, we adopted 40-inch as the initial study model and manufactured samples for the comparison between the measurement data and the simulation one. It is got that there is not much bias between them. Hence, by the employment of the reliable simulation, the designers can get the LED junction temperature quickly. Based on the measurement data and simulation result, it is known that, the junction temperature of LED is around 16℃ higher than the surface one. According to the evaluation of the overall module efficiency, it is learned that different LED models have different effects on the luminance and the heat dissipation. LED6035 has the advantages of the luminance and the cost. LED3030 has the lowest unit thermal resistance.
Counting on the study of the 40inch model, we summarized several important parameters which are related to the heat dissipation. 46-inch is selected as the optimized size for the further study and simulation. The simulation includes the impact of the different material adoption of each parts, the heat dissipation effect of the geometry of the heat sink, and the outcome of the heat dissipation technology from the different LED package manufactures. According to the simulation, we can decide the key parts selection and cost analysis at the initial stage of the product development. The evaluation time of the heat impact on backlight module can also be shortened.
The major discrepancy of the simulated result may come from the air gap. The air gap between the printed circuit board (PCB) and the aluminum heat sink could be 11℃ as maximum, and the air gap between aluminum heat sink and the back bezel could also reach 5℃. The designers must pay more attentions on those items.
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