Patent ID: 7264851

Claim:
A bistable liquid crystal display device comprising: two cell walls enclosing a layer of a composition comprising nematic liquid crystal material and finely divided solid particles dispersed therein, at least one of said cell walls being translucent; at least one electrode on each of said cell walls for applying, an electric field across at least some of said liquid crystal material; a first surface alignment on an inner surface of one of said cell walls for inducing adjacent molecules of said liquid crystal material to adopt a first orientation, and a second surface alignment on an inner surface of the other of said cell walls for inducing adjacent molecules of said liquid crystal material to adopt a second orientation which is different from said first orientation; said nematic liquid crystal material being arranged so it has a first stable molecular configuration in response to a first unidirectional electric field of a first direction and suitable magnitude and duration being applied across said electrodes and a second stable molecular configuration in response to a second unidirectional electric field of a second direction and suitable magnitude and duration being applied across said electrodes, said second configuration being different from said first configuration, the first and second directions being opposite to each other; and drive electronics for applying the electric field to the electrodes, the electric fields and the cell walls being such that (A) (a) the first surface has a molecular alignment that is always homeotropic while the electric fields are applied to the electrodes, and (b) the second surface has a molecular alignment that is planar in response to the electric field extending in the first direction, and switches to homeotropic in response to the electric field switching from the first direction to the second direction, or (B) (a) the first surface has a molecular alignment that is always planar while the electric fields are applied to the electrodes, and (b) the second surface has a molecular alignment that is homeotropic in response to the electric field extending in the first direction, and switches to planar in response to the electric field switching from the first direction to the second direction.