Abstract: An optical modulator comprises a layer of a ferroelectric liquid crystal material being provided between an integrated circuit and a light transmissive sheet. The light transmissive sheet and the integrated circuit carry respective electrodes which define selected areas of said layer. In use, the selected areas are addressed with data according to an addressing sequence which is repeated in successive time periods. The optical modulator includes means for providing a plurality of voltage pulses to the one or more electrodes being carried by the light transmissive sheet in a given time period, thus enabling a time dithered greyscale driving scheme to be used.

Abstract: A liquid crystal device of the kind in which individually addressable regions are settable to different optical states in response to drive waveforms is described. The waveforms are used to cause the material in different regions to remain set in its existing optical state or to change to another state in dependence upon data to be input to the device, and they are pulse-like in nature and of predetermined amplitude and duration. The operating speed of the device in response to said waveform is improved by causing the profile of the waveforms to depart from the usual squared profile. In one example, the waveforms are caused to have substantially triangular leading and/or trailing edges and the profile causing the material to remain set in its existing optical state differs from that causing the material to change into another optical state.

Abstract: In a three-slot addressing scheme for a liquid crystal optical modulator, where the data waveforms comprise a data section, a charge-balancing section and a further section, the form of the further section depends upon the sequence of data waveforms. The further section or pair of adjacent further sections comprises a pair of pulses of opposite polarities which charge-balance each other. The order in which these pulses occur in the pair enhances the effect of the adjacent data section to aid or inhibit switching as appropriate. This facilitates a shorter line address time.