大尺寸發光二極體側光式背光模組散熱技術

Large size side light backlight module light-emitting diode cooling technology

邱韋誌(Wei-chih Chiu)

指導教授 ： 陳奇夆

國立中央大學/工學院/機械工程研究所碩士在職專班/碩士(2011年)

摘要

自2008年平面電視市場掀起輕薄、環保及節能的訴求為主軸下，含汞成份的冷陰極燈管已逐漸被具省電、環保、體積小、色純度高、堅固及壽命長之發光二極體所取代。在側光式發光二極體背光雖能讓電視用的液晶顯示器面板達到極致化薄度，然此設計面臨許多的挑戰，如需採用高發光效率的發光二極體、局部散熱不易、大型導光板製作良率差等問題。
本論文中為了解決大尺寸發光二極體側入式背光模組散熱問題，利用40吋當初歩的研究模型與製作樣品進行實際量測與數值模擬比對，得知數值模擬與實測值差異不大增添可信度，藉由可靠且便利的數值模擬方式可提供設計者更快速得到 LED內部的溫度。經量測與數值模擬比對可得知發光二極體表面溫度加上16℃約為發光二極體內部的溫度。在模型整體的性能評估，得知LED各型號對亮度與散熱的成效，LED 6035在光學亮度與成本佔有很大優勢，LED 3030 單體熱阻最低。
經由40吋的模型研究，我們歸納出幾項對散熱的重要參數，挑選尺寸最適中的46吋機型當研究模型，模擬發光二極體背光模組在各零件之材料選用的差異與散熱器幾何外型散熱的效果及發光二極體各廠封裝的散熱技術，綜合上面敘述利用數值模擬我們可在開發初期決定關鍵材料的選用與成本分析，可縮短設計初期熱對背光模組的影響評估。
在模擬的結果造成較大的差異在印刷電路板及散熱鋁擠之間的空氣間隙其最大可相差到11℃，散熱鋁擠與背板之間的空氣間隙也可相差到5℃，在機構設計上需格外留意。

關鍵字

背光模組 ； 發光二極體 ； 散熱技術

並列摘要

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.

並列關鍵字

backlight ； light-emitting diode ； thermal

參考文獻

[24] 黃國長，「高亮度LED之熱模擬分析探討」，國立清華大學工程與系統科學系，碩士論文(2008)。

[15] 林蘇逸，「高演色性白光發光二極體之研究」，國立台灣大學光電工程研究所，碩士論文(2007)。

[12] 呂宗蔚，「高亮度LED散熱系統之熱傳及效益研究」，國立成功大學工程科學系，碩士論文(2007)。

[2] Dekai Chen, Chi-Jen Huang, Bo Jin, ”Optical Structure of Thin-Direct-Type Backlight for TFT-LCD TV Module”,P-118, SOCIETY FOR INFORMATION DISPLAY 2009。

[26] Yung-Kan Chen, Mao-Hsing Lin, Kun-Feng Huang, ”Analysis for LED Junction Temperature in LCD Module Based on Numerical Simulation”, P117, SOCIETY FOR INFORMATION DISPLAY 2009。