Nowadays liquid crystals have widely used for optical devices, even are attractive in display. But a major problem for nematic phase is its long response time, which hinders the phase to be used in high quality displays. Surface Stabilized Ferroelectric Liquid Crystal¡]SSFLC¡^is a thin device which has fast response time and exhibits excellent bistability. It can be applied in display. But it is difficult for SSFLC to achieve alignment without zigzag defects. This defect will reduce contrast ratio of display and cause image irregularities and flickering. This article discusses zigzag defects in SSFLC device. In experiment, we use convenient rubbing method to alignment FLC with high pre-tilt PI film. And we investigate the surface properties of polyimide (PI) films rubbed with different rubbing strength. We fabricate the SSFLCs without zigzag defects, and confirm that the great rubbing strength produce more zigzag defects for FLC alignment. In addition, we discuss the topography of smooth surface results in fewer defects. Finally, with the relationship between surface energy and different rubbing strength in PI film, we show the polarity of surface energy is a important role for FLC alignment.

In our study, we use mixed polyimide method and different rubbing conditions to modify surface characteristics for producing zigzag-free surface stablized ferroelectric liquid crystal(SSFLC) device. We utilize contact angle measuring system to obtain the surface free energy and also use rotating crystal method to measure the pretilt angle. Finally, we observe optical textures of SSFLC device with polarized optical microscope. In mixed polyimide experiment, we can approximately provide the pretilt angle between 0¢X and 90¢X, and we also demonstrate different pretilt angle is modified by the surface of different surface free energy. In the end of this experiment, we obtain the better optical texture of SSFLC device in 18.3¢X pretilt angle, but part regions of the texture still possess zigzag defects. In different rubbing conditions experiment, when the cumulative number of rub is 2 or 3 times in 0.3mm pile impression, we can produce zigzag-free SSFLC device in different horizontal polyimide alignment materials.