Ferroelectric liquid crystal optical modulation device having non-pixel portions controlled to a predetermined orientation state

Claim 1

In an optical modulation device, comprising: (a) a cell structure including oppositely spaced electrodes forming a pixel portion where the opposite electrodes face each other and a non-pixel portion where the opposite electrodes do not face each other, and a chiral smectic, ferroelectric liquid crystal showing optically bistable states and disposed in a layer thin enough to release its helical structure in the absence of an electric field between the opposite electrodes over the pixel portion and the non-pixel portion; and (b) at least one polarizer; the improvement wherein the ferroelectric liquid crystal at the pixel portion is selectively oriented to assume a first average molecular axis developing a dark state in response to a voltage of one polarity exceeding the threshold or a second average molecular axis developing a bright state in response to a voltage of the other polarity exceeding the threshold; the ferroelectric liquid crystal at the non-pixel portion is uniformly oriented to assume a third average molecular axis developing a dark state in the absence of an electric field, said third average molecular axis is positioned between the first and second average molecular axes, the angle between the first and third average molecular axes being smaller than the angle between the second and third average molecular axes, the angle between the first or second average molecular axis and a central axis of orientation of the ferroelectric liquid crystal being larger than the angel between the third average molecular axis and the central axis; and the angle between the first average molecular axis and the polarization axis of the polarizer is set to be smaller than the angle between the third molecular axis and the polarization axis of the polarizer.