Anchoring ferroelectric devices

This problem is overcome by Clark and Lagcrwall in their invention of the surface-stabilized ferroelectric liquid crystal (SSFLC) device [16], shown in Figure 4.9. The liquid crystal is sandwiched between two parallel substrates with the cell gap, h, thinner than the helical pitch, P, of the liquid crystal. The inner surface of the substrates is coated with alignment layers which promote parallel (to the substrate) anchoring of the liquid crystal on the surface of the substrate. The smectic layers arc perpendicular to the substrate of the cell, while the helical axis is parallel to the substrate. Now the helical twist is suppressed and unwound by the anchoring. 

In a ferroelectric liquid crystal by reducing the cell gap of a cell to a critical value, the helix of the LC medium is unwound and the FLC medium takes a planar conformation due to the surface anchoring effect [35]. This device is called surface-stabilized (SS)-FLCD [35]. 

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