Opto Electronic Liquid Crystal Display - Data Book 1977/78 [antikvár]

General technical data Liquid crystals Liquid crystals are organic compounds. In their liquid phase they pass, depending on ambient temperature, the anisotropic and isotropic state. The anisotropic state is alsó denoted as the „mesophase". solid phase liquid phase solid anisotropic isotropic crystalline liquid state liquid state phase „mesophase" -> Ts Tk temperature melting point clearing point The liquid crystal exhibits certain crystalline properties within the mesophase only, as for example double refraction. These properties are exploited for displaying information. Therefore the mesophase condition alsó defines the operating temperature rangé of liquid crystal displays. It is limited by the melting- and clearing point respectively. In the isotropic liquid state the liquid crystal does not show further particular optical or mechanical properties. Liquid crystals occur in three main types, which differ in their molecular structure. For liquid crystal displays nematic liquid crystals are used. Construction of displays The cell iscomposed of two parallel glass plates. The plate spacing is approx.10(jm. The inner parts of the plates are coated with transparent electrodes, etched in their configuration required. The plate spacing is obtained by a glass frit frame, which alsó fixes the maximum extent of the active display area. Plates and glass frit frame are sealed at high temperature, the cell is fiiled with a nematic liquid crystal through a filling hole. After filling the cell, the filling hole is sealed hermetically. In contrastto displays in dynamic scattering mode - their construction has been described afore - displays in field effect mode need different electrodes and another type of liquid crystal. The front and rear of the cell is covered with polarizers after the filling process.