Supertwisted nematic mode

The performance of STN (supertwisted nematic)-mode LCDs has been improved so far that STN displays can be used for many applications with low and high informational content [1], In particular, in price-sensitive applications they have proven to be competitive with the progressive TFT (Thin Film Transistor) technology. However, the usage of reasonable film-compensated STN displays has almost been restricted to environments with rather stable surrounding temperatures, which still is an obstacle for their widespread use, e.g. for car equipment or mobile applications. 

T. Scheffer and J. Nehring, Twisted nematic and supertwisted nematic mode LCDs, in Liquid crystals-applications and uses, Vol. 1, ed. B. Bahadur (World Scientific, New Jersy, 1990). 

See, for example, Scheffer, X, and J. Nehring. 1993. Twisted nematic and supertwisted nematic mode LCDs. Liquid Crystals Applications and Uses, B. Bahadur (ed.), Singapore World Scientific. see also Kataoh, K., Y Endo, M. Akatsuka, M. Ohgawara, and K. Sawada. 1987. Apphcation of retardation compensation A new highly multiplexable black-white hquid crystal display with two supertwisted nematic layers. Jpn. J. Appl. Phys., Part 2 26 L1784. 

Thermotropic cholesterics have several practical applications, some of which are very widespread. Most of the liquid crystal displays produced use either the twisted nematic (see Figure 7.3) or the supertwisted nematic electrooptical effects.6 The liquid crystal materials used in these cells contain a chiral component (effectively a cholesteric phase) which determines the twisting direction. Cholesteric LCs can also be used for storage displays utilizing the dynamic scattering mode.7 Short-pitch cholesterics with temperature-dependent selective reflection in the visible region show different colors at different temperatures and are used for popular digital thermometers.8... 

High contrast and uniformity of transmission characteristics at oblique incidence are also beneficial features of the SBE mode which considerable improve the legibility of supertwist displays. Better viewing angles than that for the 90° twist structure seem to be a peculiar feature of highly twisted chiral nematics. Figure 4.23 demonstrates this for a 200° supertwist cell in comparison with the usual 90° twist cell [127]. 

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