Ferroelectric liquid crystal devices having reverse twist angle and stable states resulting from A.C. excitation

A liquid crystal apparatus, comprising:

• (a) a liquid crystal cell having a pair of substrates each having a uniaxial orientation axis and a ferroelectric liquid crystal disposed between the substrates, the uniaxial orientation axes respectively provided to said pair of substrates intersecting with each other at an intersection angle .theta. so as to provide a first bistable state of the ferroelectric liquid crystal including two stable molecular orientations which form an angle twice a first tilt angle .circle.h in the absence of an electric field;
• (b) means for applying an AC voltage to provide a second bistable state of the ferroelectric liquid crystal including two stable molecular orientations which form an angle twice a second tilt angle .circle.h ', the second tilt angle .circle.h ' being larger than the first tilt angle .circle.h ;
• and
• (c) means for applying a voltage pulse of one or the other polarity so as to re-orient the molecular orientation of the ferroelectric liquid crystal to the other molecular orientation of the ferroelectric liquid crystal placed under the second bistable state caused by the AC voltage application.