Schematic drawing of the LC director distribution of a VA cell. Left: and right: . The LC directors near the substrate surfaces could be reoriented when and the reorientation depends on the anchoring energy .
Numerical simulation for the voltage-dependent , which validates the assumption of when . The LC mixture used for simulation is Merck MLC-6608: , , , , , , and .
Experimental setup for measuring the anchoring energy of VA cells. A VA cell is placed between crossed polarizer and analyzer. The optical axis of the VA cell is oriented at 45° with respect to the polarizer.
Voltage-dependent curve of a VA cell filled with MLC-6608. In the high-voltage region, a linear curve is observed and the intercept at is .
Illustration of the intercept extrapolation method described in Eq. (6). A linear fitting is obtained in the region. The intercept at leads to . A VA cell filled with MLC-6608 is used as an example.
Illustration of the slope fitting method according to Eq. (7). A linear fitting between and is observed, and the anchoring energy is deduced as . A VA cell filled with MLC-6608 is tested as an example.
Illustration of the slope fitting method according to Eq. (10). A linear fitting and a measurement result of are obtained for the MLC-6608 VA cell. The LC cell capacitance measurement is avoided by adopting Eq. (8).
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