We have investigated the electro-optic transmittance of twisted nematic liquid crystal(TN) under various a.c. electric field amplitudes and frequencies. The area(A) of the electro-optic transmittance hysteresis loop of TN scales as A ∝ $(E_m - E_{th})^{0.64}Ω^{0.78}$ in the limit Ω → 0. It indicates the possibility of hysteresis loop scaling where the hysteresis loop is originated not from the first order phase transition but just competition between the characteristic time of the system and the period of external oscillating field. Also we have calculated the switching time, using the general area scaling function, which is in reasonable agreement with the results of the direct switching current measurement.
