| 摘要: | 本論文旨在改善側打式背光板中最大光強度偏離正視方向（0度）之問題。為達成此目標，本文針對背光板中各主要光學結構進行模擬分析，依序探討導光板底部微結構、擴散片與增亮膜上稜鏡結構之設計對光強度分布與指向性之影響。模擬結果顯示，單純改變導光板的微結構形狀，不改變排列順序，對改善光的指向性影響有限。相較之下，選用半高全寬較大的擴散片可有效將光強度分布集中於 0 度方向，顯著改善垂直方向的指向性表現，實驗量測亦驗證此一結果。惟在使用擴散片半高全寬增大後，整體模組的效率與最大光強度明顯有下降。然而，透過調整增亮膜上稜鏡的幾何結構，模擬結果顯示指向性可進一步優化，強度峰值位置成功導向 0 度，且整體效率變化不大，最大光強度反而有所提升，顯示稜鏡結構之設計對改善背光板光型具有高度影響力。
綜合而言，本研究透過光學模擬得知，使用散射能力較強之擴散片與改變增亮膜的稜鏡結構，能有效提升側打式背光板正向視角的光強度。其中非對稱式稜鏡結構設計之增亮膜能在不犧牲最大光強度的的情況下，將原本最大光強度之垂直視角為7.96度時，改變至0度。
;This study aims to address the issue of the maximum light intensity deviating from the normal viewing direction (0°) in edge-lit backlight modules. To achieve this goal, a series of optical simulations were conducted on the key optical components of the backlight module. Specifically, the effects of the microstructures on the bottom surface of the light guide plate, the diffuser sheet, and the prism structures of the brightness enhancement film on the light intensity distribution and directionality were systematically investigated.
Simulation results indicate that merely altering the arrangement or shape of the microstructures on the LGP has a limited impact on improving light directionality. In contrast, employing a diffuser with a larger full width at half maximum effectively concentrates the light intensity distribution toward the 0-degree direction, significantly enhancing vertical directionality. Experimental measurements further validated this finding. However, increasing the FWHM of the diffuser also leads to a noticeable decrease in both the overall module efficiency and the peak light intensity.
To mitigate this drawback, geometric modifications of the prism structures on the BEF were explored. Simulation results show that these adjustments can further optimize directionality, successfully redirecting the intensity peak toward 0 degrees. Notably, these improvements were achieved with minimal changes to overall efficiency, and even an increase in peak intensity was observed. These findings highlight the critical role of prism design in shaping the optical characteristics of backlight modules.
In summary, optical simulations in this study reveal that high-scattering diffusers and modified BEF prism designs can effectively enhance the frontal light intensity of edge-lit backlight modules. Among the various configurations examined, an asymmetric prism structure demonstrated the ability to shift the original peak intensity angle from 7.96° to just 0° without compromising peak intensity, underscoring its effectiveness in improving directional light output.
Keywords: Edge-lit Backlight Module, Directionality, Diffuser, Brightness Enhancement Film (BEF), Prism Structure |
