Lcd Tv Gamma Features Automatic Measurement And Correction System

If the transmission characteristics are linearity in all parts of LCD TV, then the color light from TFT panel is direct ratio with the color light from photographed natural scene, At the same time the color light can be correctly transmitted and recurred. When imposing voltage on liquid crystal, liquid crystal orientation is changed and the light intensity of passing liquid crystal is adjusted. When three color (red, green, blue) liquid crystal are driven by voltages, the intensity of each color light is controlled separately and all kinds of color can be correctly recurred. Actually the transformation characteristic between electricity and light is not linearity in TFT panel, the relation between input and output is GAMMA curve. In LCD TV if input signal is U, output signal is L, there is the formula: L=KU~Y. In this instance, that input is not direct ratio with output, even the transmission characteristic of each color signal is same with another, but ratio between three colors is absolutely changed, so it result in abnormality of luminance and chroma.The automatic measurement and emendation system of GAMMA characteristic for LCD TV use the special probe that can receive light signal, then light signal is transformed into electrical signal that is transmitted to a color analyzing instrument. The color analyzing instrument can display the chroma coordinate and luminance characteristics data that are transmitted to microcomputer through serial port RS-232. The microcomputer provides RGB digital output signal and Av output signal for LCD TV. These signals include patterns of red field, green field, blue field or white(gray) field and so on. When measuring, scale of these signals is increased in some interval time by microcomputer. Software in microcomputer will accordingly record every output from color analyzing instrument while every signal is inputted into LCD TV. So we can obtain relation graph between one output from signal source and another output from LCD TV.When driving voltage on liquid crystal of TFT panel is emended, the emendation of GAMMA curve in LCD TV is also realized. There is a emending circuit for GAMMA in internal circuit of LCD TV , the circuit has the function of looking for data. The emendation of GAMMA curve in LCD TV is only looking for appropriate emending data that is inputted into GAMMA emending memory in LCD TV, so color pictures can be correctly transmitted and recurred.