Liquid crystal display device

A liquid crystal display device comprising:

• a layer of a chiral liquid crystal material disposed between first and second substrates;
• and means for applying a voltage across the liquid crystal layer;
• wherein a first region of the liquid crystal layer is an active region for display and a second region of the liquid crystal layer is a nucleation region for generating a desired liquid crystal state in the first region when a voltage is applied across the liquid crystal layer, wherein the ratio of the thickness d of the liquid crystal layer to the pitch p of the liquid crystal material has a first value (d/p)A in the first region of the liquid crystal layer and has a second value (d/p)N different from the first value in the second region of the liquid crystal layer, and wherein the value (d/p)N of the ratio of the thickness d of the liquid crystal layer to the pitch p of the liquid crystal material in the second region of the liquid crystal layer is selected such that, when no voltage is applied across the liquid crystal layer, the liquid crystal state stable in the second region of the liquid crystal layer is topologically equivalent to the desired liquid crystal state, and
• wherein the values of the ratio of the thickness d of the liquid crystal layer to the pitch p of the liquid crystal material in the first and second regions of the liquid crystal layer are selected such that, when no voltage is applied across the liquid crystal layer, a first liquid crystal state having a first twist angle is stable in the first region of the liquid crystal layer, and a second liquid crystal state having a second twist angle different from the first twist angle is stable in the second region of the liquid crystal layer, after repeated applications of voltage.