A liquid crystal display device suitable for a matrix display of a large number of lines of picture cells can nevertheless provide high contrast. The liquid crystal material used in the device is suitable for operating in the twisted nematic mode and has a dielectric anisotropy which is positive at low frequency and negative at high frequency. A timing signal is provided to the picture cell, the timing signal comprising a high frequency component and a low frequency component such that the dielectric anisotropies of the liquid crystal are at least nearly equal and opposite in sign. In addition a data signal is supplied, said data signal being equal in frequency to one or the other of the components in the timing signal. The signals are utilized in driving the display by suitable matrix-addressing.