Development of a simulation technique for thin‐film transistor liquid‐crystal displays

Abstract For active matrix liquid crystal displays (LCDs) using amorphous silicon thin‐film transistors (a‐Si TFTs), a novel simulation technique was developed. This simulation technique makes it possible to analyze accurately the fluctuation in the source voltage of the gate voltage trailing edge (feedthrough voltage) that is the main cause of image quality degradation in the TFT‐LCDs; consequently, we can accurately predict the image quality in the TFT‐LCDs. The following are the two features: (1) a‐Si TFT model considering the intrinsic capacitance which causes the dependence of the feedthrough voltage on the drain voltage is constructed; and (2) an analysis method for the gate voltage waveform distortion to calculate the difference of the feedthrough voltage between pixels depending on each pixel position in the TFT‐LCD has been extended from the analysis using an RC delay circuit to a matrix analysis using TFT matrix network. The feedthrough voltage obtained by this simulation method agrees with the measurement within 10 percent.