For The Gamma Correction, The Small Size Of Tft-lcm

With the development of micro-electronic technology and science of material, display technology is improved rapidly, resulted in bringing up many new flat panel display technologies, which show excellent display quality close or even beyond the display quality of traditional CRT display technology. TFT-LCD is one of the newly developed flat panel display technologies, which is widely used because of the maturity of its mass production technology.Basically speaking, the display theory of liquid crystal is to change the alignment direction of liquid crystal with a certain level of voltage, so that the transmission is changed with different voltage levels. If the input and output signals of LCD are linearity, the output image can be correctly transmitted and recurred. But in fact, the input and output signals of LCD are in a non-linear relationship because of its special transmission characteristic. So, gamma correction for LCD is quite necessary. If input signal is U, output signal is L, there is the formula: L = k-Uγ. In this instance, the luminance and chroma are absolutely changed.The main purpose of this paper is to do research on gamma correction for small size TFT-LCM, and develop software programs for gamma correction of small size TFT-LCM, so that the display quality of TFT-LCM can be adjusted conveniently. In another aspect, this software can also play a role of teaching application. An USB test board is also designed to make the gamma correction much more convenient.As the gamma correction theory is based on the liquid crystal display theory, liquid display theory is first introduced in this paper, which highlights the importance of gamma correction for TFT-LCD. The detail theory and application scheme of gamma correction are discussed in the next chapter. Then, the design of USB test board is introduced.After that,the design of software is described in detail, including two basic parts: gamma correction and USB transmission. USB device driving program, LCM initial code sending, image transfer are included in the USB transmission part. The gamma correction part is programmed by the combination of Visual C++6.0 and MATLAB6.5, including the load and read of csv file, calculation of ideal grayscale voltage, calculation of grayscale voltage based on gamma control registers and other relative registers, the compare of actual and ideal gamma curve.Finally, the effect of driving IC registers on actual gamma curve is discussed and measured, as well as the actual process of gamma correction. Further improvement is also proposed.