Memory angle

It is known that memory angle depends on surface pretilt angle. The temperature dependences of the memory angles of the CIU and C2U states were measured for all cells, and are shown in Figs 5.1.17(a)-(c). The solid lines represent the... 

Fig. 5.1.18 Wavelength dependence of the memory angles of the CIU state (O) and the C2U state ( ).

For simplicity, ignoring the effect of the polarization electric field on the elastic deformation [23], it is assumed that changes with Y at a constant rate. According to Kawaida etal. [24], the wavelength dispersion of the refractive indices was taken into account in the calculation of transmission. The wavelength dependences of the memory angles and the transmission spectra of CS-1014 0 — 20.0° and 6 — 18.0°) and PSI-A-2001 (0p = 15°) were calculated. 

These director profiles were calculated for CS-1014. The simulated memory angles of each director profile are shown in Fig. 5.1.25. In Fig. 5.1.26, the calculated transmission spectra for each director profile are shown. These figures indicate that memory angle and the transmission intensity in the bright state depend on the... 

Fig. 5.1.24 Relationships between the surface pretilt an e and the memory angle of the CIU state (O) and the C2U ( ) state at 25°C for (a) CS-1014, (b) SF-1212 and (c) SCE-8. Solid lines indicate simulation results by using the models.

It is shown that memory angle 0m is approximately equal to half of the total director twist angle in the cell and determined by the following equation,... 

On the other hand, the memory angle of the C2U state increases as the surface pretilt angle decreases. However, the memory angle of the C2U state seems from observations to be almost constant, because it depends only slightly on surface pretilt angle. 

In a sense, the bookshelf layer structure (shown in Fig. 6.1.3) is the ideal molecular orientation for an SSFLC. One of the greatest merits of the bookshelf layer structure is its wide memory angle. The ideal memory angle in an SSFLC is 22.5° because the transmission of light of a wavelength A is given by the following equation. 

The Cl-uniform (CIU) orientation was first reported by Koden etal. [15]. They reported that Cl states of two types were observed in FLC cells with high pretilt aligning film. One state showed extinction positions between crossed polarizers this state was determined to be the CIU state. The other state showed no extinction positions with crossed polarizers this state was determined to be the CIT state. The team reported that material in the ClU state also has a larger memory angle than material in the CIT or C2 states. Their report implied that the CIU orientation prepared by using a high pretilt aligning film is applicable to practical FLC displays. 

Fig. 6.1.14 Memory angles of the SF-2692 FLC material the r-Vmin mode under bias voltages [27].

The r-Vmin characteristics are shown in Fig. 6.1.10. The material showed a wide memory angle under the bias voltages shown in Fig. 6.1.14, giving it a high brightness. 

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