Electrically controlled birefringence displays

Switchable birefringence film Supertwisted nematic (STN), ferroelectric (FLC), electrically controlled birefringence (ECB) displays... 

The many different kinds of LCDs " based on electrically controlled birefringence (ECB) are variants of the Freedericksz effect first reported in the 1930s. These related display types based on the same electro-optical effect, but a slightly different display configuration are denominated by a multitude of names. However, current versions of this type of display are now often referred... 

When a voltage U > is applied, the sample is deformed. The retardation between the wavefronts of the ordinary and the extraordinary rays of transmitted light is dependent on the applied voltage. The effect is called DAP-effect (Deformation of Aligned Phases) or electrically controlled birefringence and can be applied in display devices [52—55] (see third part of this book). 

Liquid Crystal Matrix Display by Electrically Controlled Birefringence... 

M. Hareng. G. Assouline. and E. Leiba, Liquid Crystal Matrix Display by Electrically Controlled Birefringence, Proc. IEEE, 60, p. 913 (1972). 

Ong, H. L. 1991. Electro-optics of electrically controlled birefringence hquid crystal display by 2 X2 propagation matrix and analytical expression at obhque angle. Appl. Phys. Z-eff. 59 155-157. 

Electric field is also expected as an effective external field to drive finite and fast deformation in LCEs, because, as is well known for low molecular mass LCs (LMM-LCs), an electric field is capable of inducing fast rotation of the director toward the field direction [6]. This electrically driven director rotation results in a large and fast change in optical birefringence that is called the electro-optical (EO) effect. The EO effect is a key principle of LC displays. Electrically induced deformation of LCEs is also attractive when they are used for soft actuators a fast actuation is expected, and electric field is an easily controlled external variable. However, in general, it is difficult for LCEs in the neat state to exhibit finite deformation in response to the modest electric fields accessible in laboratories. Some chiral smectic elastomers in the neat state show finite deformation stemming from electroclinic effects [7,8], but that is beyond the scope of this article we focus on deformation by director rotation. 

To exploit the electric field-induced birefringence in display applications, the polarization of the incident light through the optical retardation produced by the induced birefringence is simply controlled in a manner similar to the mode of retardation control used for in-plane switching (IPS). If a simple comb-shaped IPS electrode is used for the device, the optical axis of the induced birefringence is parallel to the electric field, and the optical axes lie mainly in a plane perpendicular to the comb [21, 22]. A typical voltage-transmittance curve is shown in Fig. 8.18. 

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