The Liquid Crystal Electro-optical Nonlinear Effect Correction Technology Research

Projection display technique has been growing up rapidly in the 1990's. The major advantages of projection display are large screen display (from 40" to several hundreds inches), high brightness (even more than 10,000 lumens), high contrast and high resolution, etc. Projection display is becoming the mainstream in the modern display field. Liquid Crystal Projection Display, one of the most important projection display techniques, has shown the tendency for substituting the CRT projection display in the conventional video display field. Liquid crystal has many special advantages, but the image reproduction is poor because of the nonlinear effect of liquid crystal. In order to compensate the nonlinear effect, the gamma correction in liquid crystal display is discussed in this paper.In addition to introducing the basic knowledge about liquid crystal, the principle of liquid crystal display and some typical systems of liquid crystal projection display, this paper lays stress on analyzing the nonlinear transmittance performance of liquid crystal and some general correction methods. The ideal transfer function between the outputting luminance and inputting signal in liquid crystal display is probed into, and then the particular principle of Look-Up-Table which is used to correct the nonlinear transmittance of liquid crystal is detailedly discussed in order to achieve the goal. Based on the principle of gamma correction, three correction methods are set forth and simulated through numerical value computing, the results of simulation prove that the impact caused by the variable chromaticity of the primaries can be avoided completely and the transfer function of liquid crystal projection system is closely accorded with the ideal.Furthermore, a practical gamma correction system is developed based on the principle of gamma correction, including the design of hardware and software of the system. Meanwhile, the impact on the effect of gamma correction of general signal process AD in liquid crystal driving circuit is considered by using this system and simulated in theory. The correction results show that this system is rapid and convenient and the system satisfies the requirements in industrial production.Finally, the whole project is summarized and prospected. And then the signal process flow which can realize the sRGB standard in liquid crystal display is proposed and simulated through numerical value computing, the simulation result shows that this flow is fully feasible.