Prevention of uneven color for TFT-LCD TN curve panel

摘要

Uneven phenomenon will appeare when TFT-LCD (Thin Film Transistor-Liquid Crystal Display) TN curve panel used with WV (Wide View) polarizer. In the curve state, the mechanism of uneven color is speculated that there is non-uniform stress inside the panel when it is forced bending. 812.8 mm(32 in) TN curve panel is used as an example to discuss and research the uneven color phenomenon. For the problem of uneven phenomenon, the paper proposes two effective methods to improve uneven color phenomenon : First, increasing dark state brightness, the uneven color phenomenon is covered. The experimental results show that the adjustment circuit makes the display dark state brightness increase from 0.18 cd/m(2) to 0.25 cd/m(2), and the color uneven area is reduced from 30% to 10 %. But the circuit adjustment makes the display response time increase to 2.5 times. The angle of the absorption axis is adjusted from 135 degrees to 134.5 degrees, and the area of color unevenness is reduced to 10%, and the adjustment of the absorption axis angle of 0.5 degrees will reduce the contrast by 20%, which is detrimental to product performance influences. Homogenizing the stress in the TN curve panel is the second method, this paper improves the color unevenness by experiments such as increasing the cell gap of the panel, high temperature aging, and reducing the thickness of the glass substrate of the panel. The experimental results show that reducing the thickness of the glass to 0.2 mm and aging at high temperature for 72 h can make the color unevenness disappear without adversely affecting the product performance.