林晃巖臺灣大學：光電工程學研究所葉佳聖Yeh, Chia-ShengChia-ShengYeh2007-11-252018-07-052007-11-252018-07-052007http://ntur.lib.ntu.edu.tw//handle/246246/50694現行的液晶顯示系統中利用彩色濾光片來達到全彩的效果是非常普遍且必要的，然而利用彩色濾光片，會使光使用效率下降至只有33%。為了解決這個問題，我們在現有的液晶顯示系統裡，在背光源和彩色濾光片之間加入分光光柵結構，以達到讓背光源經過此光柵結構後分別分成紅色、綠色及藍色，且分別射入不同次像素。 我們利用Fraunhofer 繞射理論為基礎來模擬分析光柵結構並且分析其繞射效率以及色彩表現。我們利用調整光柵參數(包含光柵階數、光柵高度以及中心波長)，分別對三種不同的光源(CCFL、UHP和LEDs)來做模擬。 從模擬的結果得知，在加入光柵結構後光的使用效率跟傳統CCFL系統比可以增加93.8%，且在色空間方面可以增加20.8%。對於UHP和LEDs 光源而言，光使用效率分別增加91%及107%，並且色空間分別增加10.2%及12.7%。所以我們可以藉由加入分光光柵結構來同時達到提高光的使用效率，並且增加色域空間的結果。It is fundamental to use the color filter (CF) in LCD system to achieve a full-color display. For this purpose, however, the total power efficiency will plummet to 33% when the light passes through the CF. In order to alleviate this problem, we have developed a novel approach by inserting a diffractive color separation grating between the backlight and the CF to spatially separate the RGB (red, green, and blue) lights and then the three bands can be directed into three different corresponding sub-pixels. We simulated such multiple-level gratings based on Fraunhofer diffraction theory and analyze the diffraction power efficiency and color performance for the new backlight systems. We take three different light sources (CCFL, UHP, and LED) as our simulation examples and design the corresponding grating structure (the period, step and height of the grating) for each light source. The simulation results we derived for CCFL backlight demonstrate that we can get the best power efficiency improvement by 93.8% as compared with the conventional system. The gamut area can be improved by 20.8% as well. For the other two backlight systems (UHP and LED), we can design the gratings and get the best brightness efficiency improvement by 91% and 107% and gamut area improvement by 10.2 % and 12.7%, respectively. In conclusion, by adopting this novel approach we can successfully achieve the goal of improving total power efficiency and enhance the color performance at the same time.摘要 ii Abstract v Table of Contents vii Chapter 1 Introduction 1 1.1 Display Technology 1 1.2 Introduction of Liquid Crystal Display System 2 1.3 Micro-optics Device 3 1.4 Diffraction optics element 4 1.5 Fabrication of diffraction optics element 4 1.6 Motivation 6 1.7 Content 7 Chapter 2 Principle of Color Separation Gratings 8 2.1 Phenomenon of Diffraction 8 2.2 Definition of Helmholtz-Kirchhoff 9 2.3 Diffraction Formula of Rayleigh-Sommerfeld 13 2.4 Diffraction Formula of Fresnel and Fraunhofer 15 2.5 The Damman grating 18 2.6 Color separation grating used in LCD system 21 Chapter 3 Simulation Result and Discussion of Optical Performance 22 3.1 Analysis of Changing the Parameter of CSGs 22 3.1.1 Changing the number of steps 23 3.1.2 Changing the height of step 25 3.1.3 Changing the Central Wavelength of CSG 26 3.2 The Setting of Parameters for CSGs 27 3.2.1 The Setting of Red CSG (RCSG) 27 3.2.2 The Setting of Green CSG (GCSG) 30 3.2.3 The Setting of Blue CSG (BCSG) 31 3.2.4 Period Setting of CSGs 33 3.3 The CSG Setting and Simulation Result for CCFL 35 3.4 The CSG Setting and Simulation Result for UHP 51 3.5 The CSG Setting and Simulation Result for LED Light Source 67 3.6 Color Performance 83 Reference 883864853 bytesapplication/pdfen-US光柵分光光柵gratingcolor separation gratingdiffractive color separation gratingthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/50694/1/ntu-96-R94941083-1.pdf