Polymer dispersed liquid crystal (pdlc) display apparatus

Abstract

A polymer dispersed liquid crystal display apparatus has a liquid crystal/polymer medium formed between spatially disposed electrodes formed spatially disposed substrates. The medium includes a polymer phase and a liquid crystal phase having optical axes alignable together in a predetermined direction. A light absorption additive is included in the liquid crystal phase to provide light absorption when said optical axes are aligned in said predetermined direction so that in the presence or absence of an electric field applied between said electrodes, two different conditions are achieved comprising alignment and misalignment of the optical axes of the liquid crystal phase relative to the polymer phase so that in one condition, a light absorption state is created in the medium and in the other condition, a light scattering state is created in the medium. The polymer phase comprises a network including a plurality of continuous strings of particles connected in helicoid formation due to the addition of a chiral component, and this network may also include separate discrete polymer particles. Also a matrix network may be employed. A reflecting surface on the side of the liquid crystal/polymer medium opposite to that of incident light will enhance the light scattering and light absorbing properties in either of the two different conditions. Alternatively, the opposite side may be a white surface providing for a high contrast display with light absorption additive in the medium of dark contrast, such as, black dichroic dye.