Fast switching in a bistable 270° twist display

Sprang, H. A. van; Aartsen, R. G.; Vaan, Adrianus J. S. M. de

doi:10.1063/1.336936

Cited by 9 publications

(1 citation statement)

References 9 publications

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“…The earliest research on the 270° twisted nematic display was done by Scheffer and Nehring [4]. They used high pretilt angle (around 20°) to avoid the inverse twist in the on-state, and so did the reports followed [1,5,6,7]. High pretilt angle results in fast turn-on time, but very long relaxation time because of weak elastic torque.…”

Section: Introductionmentioning

confidence: 99%

55.4: 270° Twisted Nematic Liquid Crystal Light Valve with Fast Response

Chen

Sun

Guo

et al. 2003

Symp Digest of Tech Papers

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By applying low pre‐tilt angle polyimide, a 270° twisted nematic liquid crystal light valve with fast response of τon< 3ms and τoff<5ms was fabricated. The polarizers were laminated as the normal 90° TN, so the 270° twisted nematic works in the wave‐guiding mode instead of the conventional super‐twisted birefringence effect (SBE) mode. In two types of 270° twisted nematic cells fabricated with different liquid crystals, two opposite kinds of optical bounce were observed in the relaxation process (after removing the applied voltage). By mixing these two types of liquid crystals, the optical bounce effect can be eliminated so as to realize fast response. A fast response device with τon<3ms and τoff<5ms were obtained without optical bounce.

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Section: Introductionmentioning

confidence: 99%

55.4: 270° Twisted Nematic Liquid Crystal Light Valve with Fast Response

Chen

Sun

Guo

et al. 2003

Symp Digest of Tech Papers

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A simple optical method of measuring the tilt bias angle of liquid crystals

Jain

Singh

Balakrishnan

et al. 1987

Cryst. Res. Technol.

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A simple optical method based on refractive indices mcasnrcment for dcterrniriing tllc tilt bias angle of liquid crystals is described. The required refractive indices n,, n, and (10 are measured by (i) Abbe's refractometer and by (ii) optical wedge method. The tilt bias angle by this technique can be determined to accuracy of f0.2" in the high tilt angle rangc (20" t o 40"). This method is rather simple and quick and dotLs not, require any extrinal magnetic field and/or knowledge of other physical constant of liquid crystals, as arc necessary in some of the earlier reported met,hods. Liquid crystal multiplexed display devices which hare come into great prominence during the last decade, depend critically for their electro-optic performance characteristics on the tilt bias angle (GOODMAN et al.) (the angle which the uniformly aligned liquid crystal (LC) molecules make a t the bounding glass surface). .A very simple, accurate arid quick method based 011 the refractive indices measuremcnt is proposed herewith. It is well known that the nematic liquid crystals are hirefringent and when a linearly polarized beam of light incidents on a thin uniformly aligned nematic slab with its E vector either parallel or perpendicular to the preferred director's direction, it experiences refractive index n, or no, respectively. However, when the IAC molecules make a finite angle (tilt bias angle) with the Founding glass surfaces, the polarized light with i t s E vector making an angle 0 with the liquid crystal

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Temperature compensation of the threshold voltage of a 270° twist (SBE) cell

Sprang

Koopman

1987

Journal of Applied Physics

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We have measured the temperature dependence of the helical pitch of a chiral nematic mixture and we show that a second-order polynomial in T * = Tc -T is a good approximation of the behavior. We determined the dependence of the threshold voltage on temperature for a sample with a helical pitch that is independent of temperature and we can show that the contribution of the liquid crystal obtained in this way is linear in temperature. Combination of this linear dependence with the expression for the temperature dependence of the helical pitch on the mixing ratio in mixtures of chiral compounds leads to an expression for the conditions of minimum temperature dependence of the threshold voltage. These data are compared with experimental results and the discrepancies are discussed.

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Fast switching in a bistable 270° twist display

Cited by 9 publications

References 9 publications

55.4: 270° Twisted Nematic Liquid Crystal Light Valve with Fast Response

55.4: 270° Twisted Nematic Liquid Crystal Light Valve with Fast Response

A simple optical method of measuring the tilt bias angle of liquid crystals

Temperature compensation of the threshold voltage of a 270° twist (SBE) cell

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