Liquid Crystals in Information Technology

Abstract

AbstractTo establish and to improve the increasingly complex interaction between man and machine requires sophisticated, versatile and compact displays. The liquid crystal display (LCD)‐technology is the only technology which is capable to display equally well the simple time information of digital wrist watches as well as the complex color images of future high definition television sets; it is a key technology in the years to come.There have been three major prerequisites for the establishment and the success of the LCD technology since the early 1970s. Namely, the discovery of potent electro‐optical field effects on which LCDs are based, the successful search for liquid crystal (LC) materials with effect‐specific properties, and last but not least, the development of the technological tools required for manufacturing LCDs.Virtually all of today's commercial LCDs are based on the twisted nematic (TN)‐ or on various supertwisted nematic (STN)‐effects. Those LC‐material properties and electro‐optical effects that essentially determine the operability of LCDs are reviewed. The performance of TN‐LCDs, STN‐LCDs and optical mode interference (OMI)‐LCDs in modern, high information content applications is shown. Included are recent developments such as TV compatible, time multiplexed OMI‐LCDs and operation of TN‐LCDs in bright LCD‐color projectors whose functional parts, such as polarizers, optical filters and modulators consist entirely of liquid crystal devices. Moreover, it is shown that planar, uniaxial alignment of liquid crystals cannot only be achieved by conventional, mechanically treated substrates, but also by a novel, photo‐induced alignment concept. Photo‐induced alignment opens up the possibility to realize azimuthal variations of the liquid crystal director on LCD‐substrates and the possibility to achieve high resolution director pattern. Thus, among many other possibilities, LCD‐stereo projection, in‐situ interference filters for STN‐LCDs and new optical storage applications become feasible.