Liquid crystal display device

Claim 1

A multiplexible liquid crystal display device, comprising: a cell having front and rear plane-parallel transparent carrier plates each having an inner face on which respective transparent electrode layers are located, said electrode layers having opposed segments, and each having an associated linear polariser; a twisted nematic liquid crystal with positive dielectric anisotropy located in the cell; a light source arranged in a fixed spatial relationship to the cell for illuminating the display directly with obliquely incident quasiparallel light; a diffusely scattering, metallic reflector disposed behind the rear carrier plate; said light source disposed such that the angle of incidence of the light relative to the perpendicular to the surface of the front carrier plate is in the range from 50° to 90° such that the display is illuminated from that direction from which, with diffuse illumination, optimum contrast for an observer is achieved; drive means for applying an effective operating voltage to selected electrode segments to switch on said selected electrode segments, wherein the effective operating voltage applied to the switched-on segments is less than 2.0 times the Freedericksz threshold voltage of the liquid crystal, and a circuit having an optical sensor for switching off said light source as a function of the irradiance of the surrounding ambient light, and for increasing the operating voltage to at least 2.0 times the Freedericksz threshold voltage.