Recent developments in liquid crystals and other new display techniques

The current state of the art in liquid crystal displays and the characteristics of other newly-developed displays, particularly electrophoretic and electrochromic devices, are discussed. The advantages and disadvantages of the different types of displays for particular applications are examined. The new liquid-crystal phase-change, guest-host system and the electrophoretic display appear to have a wide range of applications. For certain specialized devices, such as the digital watch, however, where very low voltage, low power operation is essential, the twisted-nematic liquid crystal display appears to be uniquely suitable. The electrophoretic and solid-state electrochromic systems are capable of satisfactory operation at much lower temperatures than the other types. All the systems discussed are capable of providing large area displays with a very low power consumption and give a good contrast ratio in high ambient lighting, so might be expected to fulfil some applications not accessible to the l.e.d. or plasma panel. The thermally-addressed liquid crystal panel appears to be a promising development for flat-screen data displays carrying large numbers of digits.