Maximizing electro-optic performances in the fringe-field switching liquid crystal mode with negative dielectric anisotropic liquid crystal

The fringe-field switching (FFS) mode that uses liquid crystals (LCs) with negative dielectric anisotropy is used in high-resolution FFS liquid crystal display owing to its higher transmittance over positive LC, although its response time becomes slow and operating voltage (V_op) becomes high. In the device, reduction of the cell gap is required to achieve fast response time, which results in increase in V_op in general. In this paper, we propose the FFS mode with electrode width 1 μm and distance between the electrodes 1.5 μm. In such an electrode structure, V_op decreases with decreasing cell gap to 2 μm so that a proper V_op, high LC's light efficiency of 90%, a high color temperature, and a fast response time less than 10 ms, can be achieved, which maximizes electro-optic performance of the FFS mode. In the case of LC cell with w = 3 and l = 4.5, when the cell gap (d) reduced from 4 to 2 μm, overall light efficiency of LC dropped by 16% because of rapid decrement in light transmittance through the center of pixel and counter electrodes as well as at both edges of pixel electrodes. However, when w = 1 μm and l = 1.5 μm, maximum transmittance was noticed, irrespective of the cell gap.