Linear Analysis Of Fréedericksz Transition In Nematic Liquid Crystals

We can control the director orientation by boundary conditions or applying a magnetic (electronic) field. For the liquid crystal cell, the director orients fixed because of the surface treatment. When the magnetic(electronic) field is perpendicular to the initial director, the molecules will receive the function of torque of the magnetic field and the distortion torque from the boundary constraint. They counteract at equilibrium. Once the field is larger than the threshold field, the molecules of liquid crystal tend to the magnetic field direction and they will align to the magnetic completely under some conditions i.e. it is saturated So it is important to calculate the threshold and saturation field. When the magnetic (electronic) field approaches to the threshold and saturation field, the angle is very small, we can linearize and simplify the calculation because the angle is very small. In this paper we calculate the threshold and saturation magnetic field of the Freedericksz transition with strong and weak boundary conditions. The results are same to those got by other method.We are increasingly paying close attention to the viewing-angle characteristics of the liquid crystal display(LCD). In improving the viewing characteristics of all kinds of cells, the IPS mode is getting more attention extensively, it can greatly increase the viewing angle . There is no tilt angle in the traditional IPS cell and the molecules are parallel to the surface of substrates. However, In reality, there will exist a certain tilt angle because of rubbing or orientation methods else. The threshold and saturation voltage are important technology parameters in LCD. in this paper ,by linearization method of the continuum theory of nematic liquid crystal, we show the analyzed results of threshold and saturation voltage of IPS mode with tilt angle and weak surface anchoring conditions. The threshold voltage decreases when the anchoring energy decreases andit increases as the tilt angle increases because of K33 > K22 .The saturation voltage decreaseswhen the anchoring energy decreases and it increases as the tilt angle reduces due toK22