Vertical aligned nematic

Vertically Aligned Nematic capacitive threshold voltage (volts)... 

In LCDs various LC modes of operation are applied like twisted nematic (TN) [5], super twisted nematic (STN)[6], vertically aligned nematic (VAN) [7,8], optically compensated birefringence (OCB) [9] and in plane switching (IPS) [10-12]. The LC mode used depends on the demands of a specific application, like the viewing angle, power consumption and manufacturing cost. 

Fig. 7.15. The vertically aligned nematic-hybrid aligned nematic (VAN-HAN) zenithal bistable device geometry. The homeotropic state (left) is black while the hybrid state (right) is bright.

Vertically aligned nematic Weak electrolyte model Zenithal bistable device... 

VA Vertical aligned nematic MVA Multi vertical aligned nematic HAN Hybrid aligned nematic... 

M. F. Schiekel and K. Fahrenschon, Multicolor Matrix Displays Based on Deformation of Vertically Aligned Nematic Liquid Crystal Phases, Digest 1972 Soc. for Information Display International Symp., San Francisco, Calif., p. 98. 

The generation of high pretilt angle by such an approach led immediately to the development of vertically aligned nematic (VA)-LCDs using PI films with a very high pretilt angle of 89° on the basis of the research of Pl-coated STN-LCDs. 

Oh SY, Kang SW. Photoreactive self-assembled monolayer for the stabilization of tilt orientation of a director in vertically aligned nematic liquid crystals. Opt Express 2013 21 31367-74. 

V. A. Konovalov, V. G. Chigrinov, H.-S. Kwok, H. Takada, and H. Takatsu, Pho-toaligned vertical aligned nematic mode in hquid crystals. Japanese Jourrud of Applied Physics 43, 261 (2004). 

While positive A-plates are most common, negative C-plates are gaining popularity, in particular for compensation of the vertically aligned nematic (VAN) mode. Take for example the simple VAN with the LC cell rubbed at 45° to the crossed input and output polarizers. At normal incidence, the non-select state is totally dark giving excellent contrast ratio for this mode. However, at oblique angles, as seen in Figure 5.9, there is a retardation between the ordinary and extraordinary waves. 

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