Optimization Of Optical Compensated Bend Mode

One liquid crystal display mode with characteristics of wide view-angle coverage and fast response– Optical Compensated Bend (OCB) mode is studied in this paper. The display theory and the causes of fast response and wide view-angel in this mode are all analyzed. The theoretical basis of computer simulation in OCB mode is given, including solving the directions of LC molecules using finite-difference iterative method, solving electro-optic transfer characteristic under the different voltages by the method of Jones matrix, parametric representation, and the solution method of the threshold voltage and response time in OCB mode. The causes of improving contrast ratio and view-angle coverage using compensation film are analyzed. The application of compensation film in twisted nematic (TN) liquid crystal display and vertical arrangement (VA) liquid crystal display is given.How to improve contrast ratio and view-angle coverage using compensation film in OCB mode is studied. Four structures of film-compensation are given, including compensation using two biaxial compensators, two -c compensators and two +a compensators, one–c,one -a and one +a uniaxial films, and using two -c compensators and two -a compensators. Good optimization results are obtained using these four compensation structures by optimizing some parameters such as the azimuth angles of LC, polarizer, analyzer, compensators and so on. The maximum contrasts are all above 2200 and the total response times are all below 2ms in these four compensation structures. After optimization the view-angle coverage is large using two -c compensators and two +a compensators. Using two -c compensators and two +a compensators we can also get a wide view-angle coverage.