Fast bistable nematic display with grey scale

We present a novel principle for a fast bistable nematic display with intrinsic grey scale. The geometry of a single pixel is the usual hybrid texture in between two conductive flat plates. The device is written by creating surface walls when an electric field is applied, above the thresholds to achieve both the planar anchoring breaking and an electro-hydrodynamic flow. Erasing is obtained by simply breaking the anchoring in absence of vortices. The distorted regions around surface walls depolarize the incident light. As the surface defect density can be modulated, a grey scale is achieved.