高精密液晶顯示元件間隙量測與光學特性之研究; Study of high precision cell gap measurement and optical properties of liquid crystal displays

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題名:	高精密液晶顯示元件間隙量測與光學特性之研究;Study of high precision cell gap measurement and optical properties of liquid crystal displays
作者:	許民宗;Min-Tzung Shiu
貢獻者:	物理研究所
關鍵詞:	液晶顯示元件間隙量測;液晶光學特性;optical properties of liquid crystal displays;cell gap measurement
日期:	2003-07-04
上傳時間:	2009-09-22 10:55:11 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	一般液晶顯示元件（LCD cell）間隙厚度（cell gap）之量測方式是利用Fabry-Perot之干涉原理，配合不同波段之光源與光譜儀作反射光強度之分析，其可針對空樣品作分析量測，但價格上較為昂貴；其他量測樣品間隙厚度之方式，是必須在已知液晶材料之相關參數與顯示元件之配向方式的條件下，量測光穿透率因相位延遲所產生之變化來反推其間隙厚度，但分析上會因配向與顯示之方式而不同，且計算上較為複雜。在液晶顯示元件之光學特性量測方面，一般利用橢圓儀可以精準量測液晶材料之尋常光折射率no與液晶非尋常光折射率ne，但是有計算複雜、操作不易，以及價格上較昂貴等缺點。本篇論文針對這些參數提供不同之量測方式，在顯示元件之間隙厚度量測方面，其量測之架構與方式較為簡易，且無論是穿透式或反射式之顯示元件皆能進行量測，計算上亦不會受限於其配向之方式；且量測之範圍比一般方式廣泛，精準度卻與其他方式相近，若再配合實驗架構之改進，與利用本實驗所設計之程式核對量測角度內所有干涉條紋之相對位置，無論是量測範圍或是精準度，皆能有所提升。在液晶與顯示元件之光學特性量測方面，可利用原有量測間隙厚度之實驗設備與架構，並配合不同之配置與本實驗所設計之程式，即可簡單地將液晶尋常光與非尋常光之折射率以及預傾角量測出來；雖然實驗精準度受限於誤差傳遞（error propagation）之因素上，但量測所需之經費與數據上之分析，其困難性較橢圓儀還低。在預傾角量測方面，本實驗在無任何液晶之相關參數下，也能進行分析與量測，只是誤差相對較大。若已知某些參數之精準值，本實驗之量測誤差量可相對減低，或是配合不同樣品之間隙厚度來進行量測比對，皆可使量測之精準度提高。本實驗之量測重點，以顯示元件之間隙厚度量測與分析為主，因為此項參數之量測結果會因誤差傳遞之效應，直接地影響其他參數量測時之精準度。實驗最後再利用穿透率模擬與實驗量測之結果作比對，並以此方式來驗證本實驗數據之可信度與正確性。 The most popular method of measuring the cell gap of LCD devices is using Fabry-Perot interference principle. Using spectrum-analyzer and light sources of different wavelength, empty cells can thus be analyzed. However, the cost is quite high. Other methods can be performed if some electrical-optical parameters of the liquid crystals are already available. Information of a LCD device's rubbing direction is also required. By measuring the difference in the transmittance due to phase delays, one can estimate the gap of a LCD cell. The drawback of this method is that the computation for cell gap estimation varies with rubbing direction, and its computation complexity is relatively high. With respect to measuring optical characteristics of LCD devices, ellipsometers have been widely utilized to accurately measure the ordinary reflectivity(no) and extraordinary reflectivity(ne) of unknown LCD cells. This method has several drawbacks of high computation complexity, diffucult technical operation, and more cost. This thesis provides a different method measuring these parameters, having the advantage of easier hardware implementation for LCD cell gap measurement. Furthermore, the computation for cell gap estimation does not vary with the rubbing direction, and it can be applied to both transmission-type and reflection-type LCD devices. The proposed method also has several outstanding characteristics: wider range of measurement, high precision compared to other methods, and its performance can be upgraded by improving hardware or using our computer programs to compare all the relative positions of possible intereference stripes A novel method has also been proposed to measure the optical characteristics of LCD devices. Using the same equipment for cell gap measurement, as well as the developed programs, optical parameters such as ordinary reflectivity, extraordinary reflectivity, and pretilt angle can be easily measured. Although the precision of the proposed method is limited to error propagation, yet the cost and computational complexity are lower than those ellipsometer-facilitated methods. Without any related optical characteristics of the unspecified liquid crystal, we can still apply our method, but the estimation error is larger. We can always decrease the estimation error if some optical parameters are available. The precision of measurement can also be increased by matching estimated parameters of different cell gaps. The proposed method focuses on providing a different way of measuring cell gap of LCD cells. Because the error-propagation effect, the precision of the estimated cell gap will directly influences the precision of other parameters. At the end of our thesis, we compared our estimated parameters with those obtained by simulation. The comparison shows the accuracy and outstanding performance of our proposed method.
顯示於類別:	[物理研究所] 博碩士論文

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