Electro-Optic Effects in Liquid Crystals

Smectic liquid crystal(S) One -dimensional long-range order, High viscosity, Optically positive uni/bi-exiality Optical axis rotation Carr 1971 change in the molecular axis by the anisotropy of the dielectric contants dielectric constants i electric conductivity J n a i 

Domain formation Williams 1963 periodic change in the orientation vector -dielectric coolants e i c n electric conductivity a n a i  

Dynamic scattering (DSM) effect Heilmeier 1968 due to turbulent flow occurring when the ionic power caused 

K shear torque coefficient, 77 viscosity, flat display RCA Co. (1968) Guesl-host effect Heilmeier 1968 the reorientation of LC molecules 

Optical axis deformation Haas 1970 shape change of the optical axis in the LC layer 

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Blinov LM, Chigrinov VG (1996) Electro-optical effects in liquid crystals. Springer, Berlin Heidelberg New York... 

E. Possible Use in the Activation of Electro-Optic Effects in Liquid Crystals... 

Besides the direct electrical induction of electro-optical effects in liquid crystals, their activation by illumination of photoconductors could be of great technical interest. This method might well permit the electro-optical properties of nematic liquid crystals to be used on a larger scale, because photoconductor activation may eventually be applied to light amplification, optical data processing, and projection display systems, or used for recording phase-type holograms. 

L. M. Blinov and V. G. Chigrinov, in Electro-optic Effects in Liquid Crystal Materials , Springer, New York, USA, 1994. 

ELECTRO-OPTIC EFFECTS IN LIQUID CRYSTAL SIDE CHAIN POLYMERS... 

The dynamics of the electroclinic effect is, in fact, the dynamics of the elastic soft mode. From Eqs. (13.18) and (13.19) follows that the switching time of the effect is defined only by viscosity and the term a(T — T ) and is independent of any characteristic size of the cell or material. It means that the relaxation of the order parameter amplitude is not of the hydrodynamic type controlled by term Kq (K is elastic coefficient). For the same reason Xg is independent of the electric field in agreement with the experimental data, shown in Fig. 13.9b. At present, the electroclinic effect is the fastest one among the other electro-optical effects in liquid crystals. 

In 1963, Richard Williams observed the formation of very regular patterns or domains in a nematic liquid crystal when the material was subjected to an electric field. This report marked the beginning of a new era in research on the electro-optic properties of liquid crystals, a field which had laid dormant for nearly 30 years. During the remaining years of the 1960 s and the early 70 s, numerous studies of electro-optic effects in liquid crystals were performed, and at the same time, investigations into the synthetic and physical chemistry of these materials were conducted. As a result of these efforts, a whole new display industry evolved. 

The experimental data confirm the linear increase in the tilt angle with increasing E for the electroclinic effect and independence Xq of E [190] (Fig. 25). The switching time Xq may be calculated more precisely if the fourth-order term in 0 is taken into account. In this case, a decrease in Xq for larger electric fields is observed [192]. At present, the electroclinic effect is the fastest of the known electro-optical effects in liquid crystals. 

A list of the important points for innovations are (1) the progress of the scientific understanding of the science and physics of the liquid crystal of around 1960 (2) the development of integrated circuit according to Jack Kilby in 1959 (3) the discovery of the electro-optical effect in liquid crystals and the invention of the LCD by Williams in 1962 (4) the development of CMOS transistors by Frank Manon Wanlass in 1963 (5) the prototype presentation of the LCD by the research group of Heilmeier at RCA in 1968 (6) the synthesis of room temperature liquid crystal MBBA by Hans Kelker et al. in 1969 (7) the synthesis of the transparent ITO electrode by Yoshiyuki Katsube in 1969 (8) the proposal of a DSM theory by the Orsay LC group and finally, (9) the decision to start the development of a simple calculator instead of a TV set in 1969. 

Blinov LM, Cigrinov VG (1994) Electro-optic effects in liquid crystal materials. Springer, New York... 

L.M. Blinov, Electro-Optical and Magneto-Optical Effects in Liquid Crystals, Wiley, Chichester, 1984. 

In order to achieve an optimum contrast for special electro-optical effects nematic liquid crystals should have definite values of birefringence. In most cases matching of refractive indices can be achieved by mixing two or more single components. Therefore the birefringence as a function of the concentration is of special interest. 

It was under those circumstances that Richard Williams, who had joined RCA in 1958, started research on the necessary materials for flat-panel displays. He investigated the relatively unknown electro-optical effect of liquid crystals that had been reported by Glenn Brown et al. in a review in 1957 [1] and in George William Gray s book in 1962 [2]. 

Display devices can also be constructed using the field effect, the cholesteric memory effect and the cholesteric-nematic phase change effect [259, 262]. The recognition of the useful electro-optical properties of liquid crystals has stimulated efforts in synthesis of new mesomorphic materials. Today, more than 6000 compounds are available but an ideal liquid crystal is still elusive. 

N.V. Madhusudana and G. Durand, Linear flexo-electro-optic effect in a hybrid aligned nematic liquid crystal cell, J. Physique Lett. 46(5), L-195-L-200, (1985). doi 10.1051/jphyslet 01985004605019500... 

L.M. Blinov, G. Durand and S.V. Yablonsky, Curvature oscillations and linear electro-optical effect in a surface layer of a nematic liquid crystal, J. Phys. II France 2(5), 1287-1300, (1992). doi 10.1051/jp2 1992200... 

The second application uses the converse flexoelectric effect, i.e. a field-induced splay-bend distortion, to generate a fast, symmetric and thresholdless linear electro-optic effect in a cholesteric liquid crystal. 

P. Rudquist, The Linear Electro-optic Effect in a Chiral Nematic Liquid Crystal, Gothenburg Institute of Physics Report, No. 314, (1993). 

W. Haas, J. Adams and J.B. Flannery, New electro-optic effect in a room-temperature nematic liquid crystal, Phys. Rev. Lett. 25(19), 1326 1327, (1970). doi 10.1103/PhysRevLett.25.1326... 

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