LIQUID CRYSTAL COLOUR DISPLAYS

摘要

A colour display formed of information of one colour on a different colour background is projected onto a screen. Light from the bulb is passed serially through a neutral polariser, a smectic liquid crystal cell, and a further polariser. The cell comprises a smectic liquid crystal material incorporating an amount of a cholesteric material and a dye contained between two cell walls carrying electrodes and surface treated to give a molecular twist and alignment to the liquid crystal material. Information is written into the cell by scanning the laser beam over the cell, causing localised heating, in combination with or without an applied electric field to form selected areas with a twisted structure on a background of homeotropic structure, or vice versa. Thus plane polarised light is passed through the cell with its plane selectively rotated or non rotated. This provides a two colour display of information of one colour on a background of the other colour. Alternatively the two coloured polarisers may be replaced by a single neutral or coloured polariser to give a black and white or coloured and white display. The display system may be replicated using differently coloured polarisers and the resulting images combined into a multi colour image on a single screen.