Browse Prior Art Database

Wide Viewing Angle LCD with Multi-Domain and Fringe-Field Disclosure Number: IPCOM000013308D
Original Publication Date: 2000-Oct-01
Included in the Prior Art Database: 2003-Jun-18

Publishing Venue



Disclosed herein is a wide viewing angle technology, where fringe field and UV-modified pretilt-angle control are combined, to achieve fast response switching. For pretilt control, UV light is irradiated to alignment layer (polyimide:PI) through mask. After UV light irradiation, low pre-tilt angle (described as 'L' area) where UV dosed, and high pre-tilt angle (described as 'H') where masked. Higher pre-tilt direction decides the liquid crystal (LC) standing direction when electric field applied. (In this case, LC's delta epsilon is plus.) The cell structure, shown in Fig.1, has protrusion on thin film transistor (TFT) substrate and slit ITO on color filter (CF) substrate to achieve high speed switching by utilizing fringe field (high electrical field between protrusion and slit edge), besides LC pretilt control. The black matrix (BM) , 10-20 um width, is put on slit area to get process margin of mask mis-alignment when UV light irradiated. Low pre-tilt area and high pre-tilt area can be created by UV dosed or UV undosed. High pre-tilt and strong electric field can help liquid crystal (LC) molecule transition and acquire high speed switching. The subpixel (Red, Green, Blue subpixel) is divided into four domain by combination of High/Low pretilt area as shown in Fig.2. The domain boundary is type 1 shown as Fig.(2-1) and type 2 shown as Fig.(2-2), where arrow shows rubbing direction. Fig.(2-3) shows the High/Low (H/L) pre-tilt combination between the domains as A-B,C-D,A-C,and B-D As shown in Fig.(2-3), adjecent domain area has different H/L combination each other, and can create four domain. The Black Matrix (BM) on the domain boundary act as both UV light mask and light shield of LC alignment disorder (disclination line) around boundaries. The slit shape and width will be arranged for protrusion shape. The slit shape will be plus(+) shape for Fig. (2-1) and crossed (X) shape for Fig.(2-2). The slit can be CF side as Fig.1 or TFT side as Fig.4. Fig.2 shows parallel rubbing case on both substrate (CF/TFT) for easy understanding. However this disclosure is not restricted to parallel rubbing, and applicable to twisted nematic (TN) structure or vertical alignment (VA) structure. 1 2