防止彎曲漏光之可撓式背光設計與製作

Abstract

在顯示器的應用中，輕薄短小和可攜帶性的特性將會使可撓式顯示器成為未來的趨勢。作為一種成熟的技術，液晶顯示器有很高的潛力發展可撓式顯示器。然而，穿透式的液晶顯示器需要背光源才能發揮效用。現有的幾種可撓式背光技術中，正面臨著均勻度或效率過低的問題。 本論文提出一藉由防止彎曲漏光以維持均勻度的可撓式背光。利用拋物線全反射鏡，特殊設計的導光板只允許光傳播方向平行於彎曲軸。導光板中的參數，包含拋物線全反射鏡和V型微結構，藉由模擬軟體進行優化。為了驗證概念，以雷術切割和鑽石刀加工製做出導光板模型。實驗結果證明，導光板分別在平坦和彎曲的狀態下，垂直導光板方向的一維均勻度皆能維持在80%以上，其中彎曲曲率半徑可以達到5公分。並且在平坦和彎曲的情況下，亮度差異(誤差函數)小於10%。此外，應用外部螢光粉技術所造成均勻的角分佈，也使得在真實情況中，人眼所察覺的亮度空間分佈一樣是均勻的。因此，本防止彎曲漏光之可撓式背光，有潛力可以應用在可撓式液晶顯示器上。

In display applications, flexibility will be a trend in the future due to the features like compactness and portability. As a mature technology, LCD has the potential for development in flexible display. However, the transmissive LCD requires the backlight for operation. Nowadays, several kinds of flexible backlight suffer from low luminance uniformity or low optical efficiency. In this thesis, the flexible backlight was proposed to maintain the luminance uniformity by bending-loss prevention. The light guide is designed to permit light propagating parallel to bending axis by parabolic TIR reflector. The parameters of light guide, including the parabolic TIR reflector and the v-cut out-coupler, were optimized by optical simulation tool. The prototype of light guide was fabricated by laser cutting and diamond turning to verify the concept. From the experimental results, the 1D uniformity from the normal of light guide could successfully kept over 80% in both flat case and bending case, which the radius of curvature could reach 50mm. Additionally, the luminance difference (error function) between in flat case and bending case is lower than 10%. Moreover, the luminance angular profile applied remote phosphor technology is uniform so that the luminance spatial profile in real case perceived by human eyes is also uniform. Therefore, the flexible backlight with bend-loss prevention has the potential to be applied in flexible LCD.