Pretilt angle control

Baur, G, Wittwer, V Berreman, DW (1976). Determination of the tilt angles at surfaces of substrates in liquid crystal cells. Physics Letters A, Vol. 56, No. 2, (Mar), pp. 142-144. Chen, TJ Chu, KL (2008). Pretilt angle control for single-cell-gap transflective liquid crystal cells. Applied physics letters, Vol. 92, No. 9, (Mar), pp. 091102. 

Microgroove surface control of pretilt angle direction... 

Microgroove alignment layers which can control the pretilt angle direction (Fig. 3.4.5) have also been proposed [9]. 

Fig. 3.4.5 The structure of a microgroove alignment layer to control pretilt angle direction.

The methods involving control of pretilt angle magnitude are similar to those involving control of alignment direction and the viewing angle dependency of the LC materials within one pixel is mutually compensated. 

Control of pretilt angles by using two kinds of polyimide [14,15]... 

Control and modification of nematic liquid crystal pretilt angles on polyimides. Figure 2, K.-W. Lee, A. Lien, J. Stahis and S.-H. Paek, Japanese Journal of Applied Physics, Part 1, 36, p. 3591 (1997). Reproduced by permission of Institute of Pure and Applied Physics. 

The pretilt angle of a PI alignment layer can also be controlled by ultra-violet (UV) irradiation (Lu et al., 1996 Yoshida Koike, 1997 Ichimura, 2000 Chigiinov et al., 2008). 

We have developed two approaches for controlling the pretilt angle of the PI alignment layers by using the conventional PI materials. The proposed methods are compatible with current methods familiar in the LCD industry. The LC devices, such as no-bias OCB LC cells, LCFLs and LC phase gratings, are demonstrated in this chapter by using the proposed techniques. A future study should examine the long-term thermal stability of these modified PI films. 

Vaughn, KE, Sousa, M, Kang, D and Rosenblatt, C (2007). Continuous control of liquid crystal pretilt angle from homeotropic to planar. Applied physics letters, Vol. 90, No. 19, (May), pp. 194102. 

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