PURPOSE: To obtain excellent contrast without no realtion to the number of digits, by driving two frequency dynamic method for the display unit using the liquid crystal caried with frequency for the anisotropy of dielectric constant.

CONSTITUTION: When the anisotropy of dielectric constant has positive value ΔL at lower frequency than the frequency fx and negative value ΔH at higher frequency than fc, if the absolute value of ΔH/(ΔL+ΔH) is greater, the value of the ratio of the effective voltage at selection condition to that non-selective condition VON/VOFF is greater, obtaining excellent contrast. Each frequency is selected so that this can be satisfied, and rectangular wave Ao at addressing (at selection) is fed at timing signal and low frequency Bo is fed at non-selection, and when CON and COFF are respectively fed as the data signal at ON and OFF in phase or opposite phase to the wave form Ao, the voltage FON(R-CON), FOFF (R-COFF) is fed to the liquid crystal video element, high harmonic is fed at selection causing OFF state and ON state is caused at non-selection.