本文擬以發光二極體(LED)為光源的7吋背光模組做為研究的對象，其理由乃因在目前的商業化中型尺寸面板方面，它的發展最為迅速，且應用亦非常普遍。本文以實驗的方式，探討LED的使用顆數、LED的亮度、導光板的厚度、及稜鏡片的使用張數對背光模組亮度表現的影響，並進一步在考量亮度表現下，選擇出最佳元件組合之背光模組，不僅可達到亮度規範的需求並可使材料成本最具經濟效益。 LED (Light Emitting Diode) of 7" backlight module is used as the researching object in this paper. It is chosen because that it is the most developed, common and widely used in all kinds of the commercial medium sized panels in nowadays. In this paper, experimental measuring method was used. The effect of working parameters on the luminance performance of 7" backlight module is investigated. These parameters, however, includes the number of LEDs used, LED’s luminance, thickness of light guide and the number of prism used. Further, by considering the luminance performance and manufacturing cost, choosing the best combination of materials. Not only the luminance can reach the specification, but also the materials selected can be made in consideration of the economic profit.