導光板網點形狀在背光模組於不同視角光強度影響研究分析

The Effect of dot shape in LGP on the luminous intensity at various view angle

廖清松(Ching-Sung Liao)

指導教授 ： 王世明

中原大學/工學院/光機電及資電控產業研發碩士專班/碩士(2008年)

https://doi.org/10.6840/CYCU.2008.00380

摘要

背光模組是由反射片、擴散膜、稜鏡片、導光板及光源組成，其中導光板是背光模組上最重要的零組件之一。導光板的原理乃利用全反射的原理是將光源光線傳至導光板的遠端，再利用導光板反射面之網點圖案，來破壞光線的全反射，將光線導引至導光板正面。目前業界均使用圓形作為導光板反射面之網點圖案，本次研究將網點圖案置換為正方形、六邊形、六邊形(轉角度)三種圖案，經電腦輔助軟體模擬不同網點圖案，且利用射出成型，將不同網點圖案實體化，組成背光模組進行平面量測、水平及垂直方向量測，再與業界常使用之圓形網點圖案作一個比較，藉此研究找出光利用率最佳的一種網點圖案。
經由此次實驗可發現，依平面量測結果來看，四種網點圖案在相同蝕刻深度下，不同網點圖案對於背光模組整體輝度分佈影響並不大，整體輝度分佈之關鍵在於Stamper蝕刻的深度。另外將平面取樣點數由9點增加至100點，藉此更容易比較出各模組之輝度分佈之差異性。水平及垂直方向量測結果來看，四種網點圖案在不同視角下之光利用率趨勢相同，正方形網點雖有較好之輝度表現，但其實對輝度的影響也很有限。改變視角的關鍵在於上下增亮膜的搭配使用，決定了背光模組整體視角的大小。

關鍵字

網點圖案 ； 背光模組 ； 導光板

並列摘要

The back light module (BLU) consists of plastic frame, bezel, diffuser sheet, prism sheets, light source and light guide plate (LGP). The LGP is one of the most key functional components. The function of the LGP is to propagate and to distribute the light energy, which is emitted from light source located on one side or the end of the LGP, and to cover all the emitted surface area. The principle of LGP is internal reflection. The bulged dot pattern, engraved on the reflection side of the LGP, destructs the internal reflection and releases the light out of the LGP. After analyzing the dot shapes used in the commercial LGPs, we found that most dot shapes are circles. The purpose of this study is to understand the effect of the variety of dot shapes on the light leakage phenomenon and to search for the best light usage efficiency by optimizing the dot shape. We apply four kinds of dot shapes. They are circle shape, square shape, hexagonal shape and rotated hexagon shape related to entrance light direction. The LGPs with different dot shape geometries are produced by mold injection and the BLUs are assembled to evaluate the performance. The BM-7 is used to measure brightness vertically and horizontally to the LED entrance side of the single LGP or LGPs with various films on it. We also conducted the computer simulation to compare the results from the practical experiments.
The effect of these four dot shapes under the same dot depth on the brightness of the LGPs is not significant from our measurements in this study. The primary factor to control the brightness distribution is dot depth. It is easy to distinguish the brightness differences among the BLUs with different dot shaped of LGPs by increasing the sampling points from 9 to 100. The same tendency is observed vertically and horizontally on these four BLUs under different view angles. The square dot shape has better performance than the rest of the dot shapes. However, the brightness of the square dot shape is finite and limited. The cross aligned prism sheets and diffuser sheets are crucial elements to control the view angle and to determine the view angle ranges of the whole BLUs.

並列關鍵字

back light module ； light guide plate ； dot shape

參考文獻

[10] 張自恭，背光模組光學設計，國家高速網路與計算中心，2002年。

[11] 楊明仁，LCD 背光模組產品介紹，台灣工業銀行，2002年9月。

[30] 張政德，背光模組導光板微結構設計對光學輝度分佈影響之研究，崑山科技大學機械工程系，碩士論文，2003年。

[1] Naehyuck Chang, Inseok Choi, Hojun Shim, “DLS: Dynamic Backlight Luminance Scaling of Liquid Crystal Display,” IEEE Tran. VLSI, Vol. 12, No. 8, Aug. 2004, pp. 837-846

[5] Takamitsu Okumura, Akihiro Tagaya and Yasuhiro Koike,Highly-efficient backlight for liquid crystal display having no optical films, Appl.Phys.Lett,83,2003,pp.2515-2517.