Patent ID: 7791706

Claim:
A bistable nematic liquid crystal display device switchable between a first homeotropic stable molecular configuration and a second stable non-homeotropic molecular configuration, the bistable nematic liquid crystal display comprising: a liquid crystal material doped with a mixture of finely-divided positively-charged nanoparticles and finely-divided negatively-charged nanoparticles, the liquid crystal material to adopt the first stable homeotropic molecular configuration in response to a first pulse of a unidirectional electric field of suitable magnitude and duration and to adopt the second stable non-homeotropic molecular configuration in response to a second pulse of unidirectional electric field of suitable magnitude and duration and opposite polarity to said first pulse, in the first stable homeotropic molecular configuration the positively-charged nanoparticles being substantially migrated to respective cell walls to shield the liquid crystal material from a surface alignment, and in the second stable non-homeotropic molecular configuration the positively-charged and the negatively-charged nanoparticles being dispersed in the liquid crystal material to expose the liquid crystal material to the surface alignment.