We have identified three smectic phases, smectic A, ferrielectric and antiferroelectric, in a free-standing film of the first component compound of the mixture which was reported to show the V-shaped switching usable for realizing attractive displays [Inui et al..: J. Mater. Chem. 6 (1996) 671]. The switching in the antiferroelectric phase, observed by applying a triangular waveform electric field to a homogeneous cell, evolves from tristable to V-shaped with increasing temperature and frequency; the V-shaped switching occurs uniformly without accompanying any domain boundary movement. The results have been discussed in terms of thresholdless antiferroelectricity in liquid crystals.