環型分區梯度變化結構導光板之設計與開發

Optical Design and Development for the Ringed Zonal V-Cut Structure of the Light Guide Plate

近年來在政府的政策推動下，國內之 TFT-LCD 顯示器產業已經蓬勃發展逐漸成熟，並已在國際與日、韓並駕齊驅，佔有舉足輕重之地位，不僅在世界消費市場中有高度的市場佔有率，各項技術亦已具國際水準，而中小尺寸LCD顯示器因其在通訊 （手機）、資訊 （PDA）、消費電子 （數位相機） 等領域有高度之需求，故亦為台灣廠商之主力出貨產品。所以中小尺寸LCD 顯示器之性能提升與技術突破已成為重要且刻不容緩之課題。而背光模組為LCD 顯示器中做為提供光源相當重要的一環。背光模組是由一片導光板及多片光學薄膜組成。當光由光源被耦合進入導光板時會因為材料界面的全反射現象而傳遞至後方；為了能導引光線離開導光板以提供作為LCD 的背光源，遂在導光板表面加上微結構，以破壞部份光線之全反射行為，將光線導引至導光板外。目前中小尺寸背光模組多採用側向式入光，造成出光角度過大，故需要使用導光板及反射片、擴散片、水平與垂直稜鏡片等光學膜片，方可使點光源的LED 或線光源的冷陰極管 （CCFL） 成為能在正視角發光的面光源 （背光模組）。本研究以光學模擬軟體 SPEOS 在導光板上設計創新之環型分區梯度變化結構並進行光型探討。從模擬結果分析得知，此一創新環型梯度變化結構確實有效改善了導光板的出光的角度 （半功率全角約15°），以至於能減少光學膜片的使用，大幅降低了零件與組裝成本；並由於光強度的提升，應可適度降低LED 光功率並維持足夠之輝度，進而達到節能省電之目的，可提升產品競爭力。

Among the technologies employed in manufacturing size LCDs whichoccupy most of the export market for mobile small to medium phones,Back Light Module (BLM) is one of the key element in the performance ofthe display. Traditionally, BLM consists of a light guide plate and severaloptical films including reflectors, diffusers, and prism sheets. Due to BLMbeing an edge emittier, the beam pattern is tilted at a large angle when the light exits the surface of the LGP and that is why we need some films tocorrect it back into a front viewing angle. In this study, the opticalsimulation software called “SPEOS” is used to design a novel structure,which has different slopes at different locations to correct the beam pattern.After simulation and analysis, the results show that the beam patterncan be fixed to a half intensity angle of about 15° to normal from the frontview angle without using prism sheets. The merits of this design are thatthe cost of films and assembly can be reduced; also because the noveldesign can increase the light intensity, power can be saved to reach the goalof energy saving. These advantages can enhance the product’s competitiveposition in international markets.