Liquid crystal display device

Claim 1

A liquid crystal display device incorporating a tandem arrangement of two liquid crystal display cells the rear cell of which has a layer of dyed nematic liquid crystal medium incorporating a chiral component providing between 90° and 360° twist of the director through the thickness of the layer, which layer is sandwiched between an electroded transparent front sheet and a rear sheet formed by or carrying a semiconductive layer provided with access circuitry by which the rear cell is addressed on a line-by-line basis via a matrix array of semiconductor gates directly or indirectly connected with an overlying matrix array of liquid crystal rear cell electrode pads, wherein the surfaces defining the liquid crystal layer are such as to promote parallel homogeneous molecular alignment at the major surfaces of layer with a relative _orientation matching the twist, and wherein the front cell of the tandem arrangement has a layer of dyed nematic liquid crystal medium incorporating substantially no chiral component, which front cell liquid crystal layer is sandwiched between a pair of electroded transparent sheets whose surfaces are such as to promote parallel homogeneous alignment at the major surfaces of the layer in a direction aligned substantially at right angles to the alignment direction promoted by the front sheet of the rear cell.