Recently, the demands for portable electronic devices such as mobile phones, digital multimedia broadcasting (DMB) phones, personal digital assistants (PDAs), navigator system and digital still cameras (DSCs) have dramatically increased as a result of expansion of digital mobile market. Liquid crystal displays (LCDs) represent the dominant trend in personal information displays because of light weight, compact and low power consumption. The majority of LCDs in the market is the twisted nematic (TN) mode owing to its excellent stability in structure and wide process margin. However, it has a problem in viewing angle and contrast ratio. Many kinds of display modes are suggested to improve the image quality of TN mode such as optically compensated bend (OCB) [1], in-plane switching (IPS) [2], fringe-field switching (FFS) [3] and vertical alignment (VA) [4]. The IPS and FFS modes show a wide viewing angle and a high contrast ratio but response time is rather slow. The multi-domain VA (MVA) mode with optical compensation film also shows a wide viewing angle, high contrast ratio and a relatively faster response time than IPS mode but aperture ratio is rather low for a small mobile display with high resolution. In this work, we developed a novel Patterned Vertical Alignment (PVA) LCD for mobile application with high transmittance and reliability by optimizing the design rule, fabrication process and LC materials. Our new design rule enabled an increase of 36% aperture ratio (A/R) and better electro-optical performance compared with those of the conventional PVA structure. The A/R of 4.3 inch WQVGA PVA LCD is 64%, the contrast ratio (CR) is 620:1, the viewing angle (CR > 10) is over 160 degrees in the horizontal and vertical viewing azimuth and no gray scale inversion were also obtained. The newly developed alignment material and ultraviolet (UV) sealant realized the reduction of face and line image sticking level. The conventional alignment material is single layer of polyamic acids (PAAs). However, new alignment material is PAA-PAA block copolymer. This double layer restrains the adsorption of ion impurity to the hydrophobic surface layer and releases the adsorbed ion impurity in the hydrophilic inside layer rapidly. And new UV sealant reduces the reactivity between LC and sealant.

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