Matrix display using a twisted nematic liquid crystal dynamically addressed

The scanning limitations of rms responding liquid crystal devices due to the lack of sharpness of the transmittance characteristic can be overcome in the case of the twisted nematic configuration. Indeed, it is possible to obtain a linear output polarization from an electrically excited cell, and then to decrease the transmittance level of the non selected dots without altering the optical efficiency for the selected dots by rotating the output polarizer perpendicularly to the transmitted vibration. A 64 × 64 element matrix display using a biphenyl compound has been constructed and operated in the transmissive mode. The contrast ratio obtained with a duty factor equal to 1/128 corresponding to a 128 line display is 20 : 1. The address and the information pulses respectively applied to the lines and the columns are V1= 12.4 V and V2= ± 1.1 V.