The Case of a Rigid Container

In very small cells or in cells made of thick glass, there may be so little deformation of the cell walls that the liquid behaves as if it were in an ideally rigid container. Very high pressures develop and these can be estimated from readily available thermodynamic data. The quantity required is (dp/dT)v, the pressure increase per degree of temperature rise when the volume is held constant. From general thermodynamic arguments this can be related to l and the compressibility /8l of the liquid. 

For most liquids the magnitude of l is around 1 X 10 deg and the magnitude of / l is around 1 X 10 atm . The pressure rises by about 10 atmospheres per degree of temperature rise. This would be a severe design limitation. About the only way it might arise in practice would be if the lateral dimensions of the cell were small if, for example the individual elements of a numeric display were made as separate closed-off cells. 

In summary, the liquid-crystal cell, though ideally a closed system, is one that reacts significantly to changes in external conditions, and this is an important consideration in applications. 

I am indebted to L. A. Goodman, D. Meyerhofer, E. B. Priestley, and P. J. Wojtowicz for valuable discussions of this problem. 

This chapter is divided into three major sections. The first describes 

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