Supertwisted birefringence effect

Scheffer T J, Nehring J, Kaufmann M, Amstutz H, Heimgartner D and Eglin P 1985 24 80 character LCD panel using the supertwisted birefringence effect Dig. Tech. Papers Int. Symp. Soc. Information Display 16 120-3... 

SEE Supertwist birefringence effect device effect in a 180° to 270° twisted nematic structure that uses a combination of interference and polarization guiding to achieve an optical effect with sharp threshold behavior, making it particularly suitable for multiplexing. 

The effects of bistability and hysteresis in supertwisted nematic layers were first investigated in [122]. To obtain twist angles larger than 90 , nematics were doped with a small amount of an optically active material. Thus a cholesteric (or chiral nematic) with a large pitch P was created, so that the pitch value had to adjust the boundary conditions for the directors on the substrates. The corresponding texture was first discovered by Grandjean and is discussed in Chapter 6. In 1984 the display based on the Supertwist Birefringent Effect (SBE) was proposed [123]. 

Thus the supertwist birefringent effect was a step forward to the development of a new generation of matrix addressed displays with very high information contents and excellent viewing characteristics. However, several characteristics of the SBE mode need further improvement. They are as follows ... 

As described above (Chapter 4), due to the birefringence effect, the first versions of supertwisted displays operated in two-color modes, i.e., yellow and blue. It was not very impressive and strongly limited their applications. Since 1987 several black-white variants of supertwist displays were proposed. Three of them are shown in Table 8.2. 

B. Bahadur, Supertwisted Dye Effect, Super-twisted Birefringence and Ferroelectric Liquid Crystal Displays, Litton Data Images Report, March 1986. 

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