Lcd Monitor Viewing Angle Characteristics, Research And Improvement

Liquid Crystal Display(LCD) has been used more and more extensively as a mainstream flat Panel display technology. Since the first LCD was invented, much endeavor has been made to improve its performance. Though modern technology can satisfy the basic requirement of people, the Problem of viewing angle of LCD has not been solved perfectly. So there are some work has been done for perfecting the LCD'S properties. In this paper, the viewing angle and the opto-electronic property of LCD has been carried out, to improve the viewing angle of LCD with wave plate instead of compensatory films.Firstly, a new LCD mode(TN) is presented in this paper. When liquid crystal is put into the electric field, the orientation of the liquid crystal molecule and the optic axis will change. A differential equation about free energy has been established. Additionally, difference iterative method is used for calculating the liquid crystal director distribution. This method can give accurate results. In the experiences the orientation of the liquid crystal director(c-axis) show a continuous distribution and the detail has showed in chapter 2.Most LCD devices are made of cell of liquid crystals sandwiched between transparent electrodes and polarizers. The devices can be divided into N+4 layers and each layer can be considered as a homogeneous and uniaxially birefringence medium ,and can be described by Berreman's 4×4 matrix. The orientation of the director(c-axis)may be changed from layer to layer. The transmission characteristics of light through N+4 layers have been treated using extended method.Secondly, an optical method is presented for which allows one to measure simultaneously the twist angle and the cell gap of a filled nematic liquid crystal display. that has a arbitrary unknown twist angle. And it can also determine the direction of handedness of the twist angle and the two rubbing direction of an unknown panel. Then the results are got that cell gap is equal to 6.1um and twist angle is equal to 91.5 . Using this method, the measurement uncertainty of cell gap is within one percent and measurement unknown certainties of the twist angle and rubbing direction are within one degree. Thirdly , the problem of LCD's viewing-angle and the technologies are studied. Based on the opto-electronic property simulation program of LCD, an Auto-optimization computer program to design wide viewing-angle films for LCD is developed. And then, the designed results of the 1/4 wave plate for twist nematic TN-LCD is offered. According to the simulation, the 1/4 wave plate can improve the viewing angle of TN-LCD.Finally, a conclusion and a prospect are made to this dissertation.