Vertical LC Alignment

Photoalignment of Liquid Crystalline Materials Physics and Applications V. Chigrinov, V. Kozenkov and H.-S. Kwok a 2008 John Wiley Sons, Ltd 

In the off-state of the proposed structure, nematic molecules align mostly perpendicular to the cell surface and are reoriented by distorted electric fields at the grating surfaces to make four different domains. The LCD cell shows excellent extinction in the off-state and wide viewing characteristics in the on-state [9], 

However, notwithstanding various efforts, the VAN-LCDs prepared by the photoaligning technique have not yet reached an appropriate quality (response time, contrast ratio) in comparison with conventional LCDs prepared by rubbing technology [2-9], 

The response times of photoaligned and conventionally rubbed VAN-LCDs were also measured. The results indicate almost no change, with ton + tog = 7.8 -I- 9 ms for the former and To -I- = 8.1 - - 8.9 ms for the latter. Probably this means that 

Alignment layer consists of a mixture of polyimide for vertical alignment and azodye photo alignment material 

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