照光電壓(VUV)對高分子穩定OCB液晶盒光電特性影響之研究

Study on the waveform of curing voltage on the electro-optical properties of the polymer stabilized OCB cell

李鎧淩(Kai-Ling Li)

指導教授 ： 吳俊傑 ； 陳殿榮

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2010年)

摘要

液晶顯示器的光學彎曲補償(Optically Compensated Bend，OCB)模式有廣視角、時間快速響應等優點，但在初始splay state外加電壓驅動到bend state的轉態過程中，需要花費的一段很長的暖機時間(warm-up time)。為了解決OCB顯示器有著臨界電壓大及暖機時間問題，本研究以微量高分子前軀體混合液晶注入OCB 液晶盒內，利用在照UV光聚合的同時施加交流電壓於液晶盒的方式，探討改變電壓波形及頻率下，對於液晶分子與光電特性之影響。
本實驗使用的交流電壓波形分別為方波、正弦波及脈衝波。實驗結果顯示：
(1) 在照UV光聚合高分子的同時施加正弦波或脈衝波的條件下，可經由改變電場頻率控制液晶分子初始在bend或twist狀態。
(2) 在形成初始bend與twist狀態下，當改變照光電壓頻率條件時，OCB液晶盒之穿透率會隨著照光電場頻率的降低而增加。
本論文針對三種不同波形照光電壓對OCB 液晶盒之光電特性，如穿透率對電壓、偏光圖、視角及響應時間等做比較。

關鍵字

高分子聚合 ； 光學彎曲補償模式 ； 電壓波形 ； 響應時間 ； 暖機時間

並列摘要

In liquid crystal display applications, optically compensated bend (OCB) mode has attractive advantages such as wide viewing angle and fast response time. However, long warm-up time is required for driving a OCB cell into the bend state due to the discontinuous of splay-to-bend transition. In addition, the transmittance of the OCB cell is fairly small because the phase retardation of the cell in the bend is generally smaller than λ/2. In the study, we improved the problem of the OCB mode display such as low transmittance and long warm-up time.
The polymer-stabilized OCB cell was fabricated with slight liquid crystal/monomer mixture concentration. An ac electric field was applied during photo-polymerization. Three kinds of electric field waveforms were mainly used in this study. They are square, sine, and pulse waveforms.
After the application of sine and pulse waveform to the cell during the curing process, the initial twist and bend states can individually be obtained in the OCB cell by adjusting the ac electric field frequency. In addition, the cells with either initial twist or bend state, carried out by the sine and pulse waveform conditions show faster response time and higher transmittance than those of cells under square waveform condition. The initial state and electro-optical properties of the cells under different waveform condition are discussed by measuring the voltage-dependent transmittance (V-T) curve, microscopic texture, viewing angle and response time.

並列關鍵字

polymer-stabilized ； optically compensated bend mode ； voltage waveforms ； response time ； warm-up time

參考文獻

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