Dependence of image flickering of negative dielectric anisotropy liquid crystal on the flexoelectric coefficient ratio and the interdigitated electrode structure

We experimentally measured the splay (e _s) and the bend flexoelectric coefficients (e _b) of liquid crystal (LC) mixtures with negative dielectric anisotropy and investigated their effect on the image flicker of the LC mixtures driven with a low frequency electric field. Using the experimentally measured e _s and e _b, we simulated the transmittance (TR) response with the continuum model. First, we confirmed that the TR simulation results were approximated to the experimental data with only small variation. Second, we varied the simulation parameters of e _s , e _b, the separation (S), and the width (W) of the interdigitated electrodes and tried to find the optimum condition showing the least image flicker. Given W = 3.0 μm and e _b = 5.7 pC m^-1, it was found that the image flicker could be minimized when the e _s /e _b value was about 2.4 and the S/W ratio was about 1.5. Because the e _s /e _b value of the rod-like LC material is generally less than 1, it is desirable to design an interdigitated electrode structure to minimize the image flicker effect.