Display device comprising a layer of liquid crystal

Claim 1

A display device comprising a mixture of a nematic liquid crystal having a negative dielectric anisotropy Δε<-1(Δε= ε.sub.∥-ε.sub.|) and being a stilbene of the formula: ##STR2## where R and R' are each alkyl, alkoxy or acyloxy of up to 8 carbon atoms with the proviso that R and R' do not both represent methyl or methoxy and an optically active material between two supporting plates provided with electrodes, said nematic liquid crystal exhibiting light scattering properties below a critical frequency when a voltage is supplied to at least two of said electrodes in a first range of voltages between a first frequency dependent minimum and a frequency dependent maximum of said voltage as well as in a second range of voltages above a second frequency dependent minimum of said voltage, said nematic crystal being transparent when subjected to a voltage between said frequency dependent maximum and said second frequency dependent minimum in a range of frequencies said second frequency dependent minimum being higher than said frequency dependent maximum, means for supplying recording and erasing voltages having the same frequency in said range of frequencies to at least two of said electrodes, said recording voltage being between said first minimum and said maximum of said voltage and said erasing voltage being between said maximum and said second minimum of said voltage.