Thermodynamic Analysis Of Rugged LCD Modules In The High Temperature

In the military environments, LCDs need to withstand high and low temperature, strong vibration and shock, high ambient brightness humidity, low pressure and so on. The ordinary commercial LCDs cannot work properly in such harsh environment, making necessary to rugginize LCDs. When a rugged LCD works in high temperature, the extra thermal stress could apperence on the upper ITO plate due to different coefficients of linear expansion of the parts, causing the display defects. Therefore, it is very significant to analyze the thermal stress distribution of the rugged LCD in the high temperature.The internal structure on a LC cell is very complicated and various, which make it difficult to establish a precise simulation model. Different form common glass, the upper plate consists of color filter film and ITO film and the rear plate consists of TFT and ITO film. As the reason that it is impossible to measure the thermal parameters of each part, the thesis puts forward the equivalent method for liquid crystal layer, LCD upper and below glass to obtain the equivalent thermodynamic parameters of the parts, combining with the practical test data and finite element simulation analysis. Because a rugged LCD module has many parts and a complex structure, the strict meshing is required. The simplified processing method is proposed to reduce the computation complex, on the premise of enough computation precision. The rugged LCD model is established with the help of the three-dimensional modeling software Pro/Engineer to analyze the thermal stress distribution in the high temperature. The thesis also analyzes emphatically the effect on the display of the some kinds of defects of the optical adhesive and the polarizer. The simulation results show that the defects both of the optical adhesive and the polarizer can induce the stress concentration on the LCD upper glass, leading to the change of cell gap and possible display defects.