Dual domain LCD

To demonstrate the actual performance improvement of a dual domain LCD, a demonstrator display has been made. In this display the domains are made by patterning a photoalignment material supplied by LG Cable. This material... 

Fig. 9.15. Viewing angle properties of a 5 inch dual domain LCD as made using the configuration shown in Fig. 9.13b.

Fig. 9.13. Configurations of the studied LCDs. Top view of a monodomain 90° TN LCD (a), and dual domain 65° TN LCD (b) and cross section of a dual domain 65° TN LCD (c). The light path through the LCD is from left to right. Compensator denotes the retardation foil.

The dual domain display has a polariser with its transmission axis parallel to the LC orientation at the top substrate (continuous arrow) and an analyser with its transmission axis crossed to the polariser. It can be seen from Fig. 9.13b that the LC orientation at the bottom surface is neither parallel nor perpendicular to at least one of the polarisers. This means that the optimum contrast (obtained when a 90° TN LCD is placed between crossed polarisers) cannot be obtained. Therefore a retardation foil needs to be inserted in the light path to optimise the contrast of the display. 

Fig. 7.10 (a) Partially switched, slightly off-vertical LC director configuration of LPP photo-aligned dual-domain VAN-LCD. (b) LPP photo-aligned, 40" Sharp TFT-MVAN-LCD TV partly switched 4-domain MV AN director configuration (inset)... 

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