Analysis and design of a-Si TFT/LCD panels with a pixel model

The design of a-Si thin-film-transistor/liquid-crystal-display (TFT/LCD) panels using a pixel model which consists of an equivalent electrical circuit and includes parasitic capacitance and the actual structure of deposited layers is discussed. The model's validity is first confirmed by comparing calculations with experimental results on a-Si TFT switching characteristics and TFT/LCD electrooptical characteristics. The gradual-channel approximation of an MOS transistor is applied to the static I-V characteristic of a-Si TFTs. This approximation is successfully used to obtain an analytical expression for pixel electrode voltage during the TFT turn-on time. The calculated dependence of the LCD panel transmittance on signal voltage is shown to reproduce the experimental results. On the basis of the analysis, a TFT-addressed 5-in.-diagonal liquid-crystal color TV has been developed which exhibits excellent display quality.<
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