Alignment instability caused by anchoring of the in-plane directors to the rubbing direction in the V-shaped switching

In order to investigate the molecular alignment in the smectic liquid crystals showing the V-shaped switching behavior, two types of the liquid crystal cells, a sandwiched cell and an open cell, were prepared. Homogeneous alignment with the smectic layer normal formed at ∼12° with respect to the rubbing direction r is obtained in the Sm-A phase in both cells. However, in the open cell, the director n is rotated towards r when the Sm-A sample is cooled into the tilted Sm-X* phase. In addition, its maximum rotation angle is ∼12°. In this configuration, the molecules lie along r. Meanwhile, the sandwiched cell with the one-side rubbing treatment exhibits the averaged optical axis almost parallel to the layer normal in the Sm-X* phase. In this paper, a simple small-twisted state in the thin sandwiched cell is suggested to account for the experimental results.