In-cell capacitive-type touch sensor using LTPS TFT-LCD technology

An LTPS TFT-LCD with an in-cell capacitive-type touch sensor has been proposed and prototyped. The embedded sensor in the pixel was designed to amplify the voltage change caused by capacitive coupling between the detection electrode and conductive object ( user's finger). No touch force is needed for sensor actuation and no extra electrical connection for the counter-substrate is needed. The validity of the observed voltage difference of the sensor output on the TFT substrate was examined. The proposed architecture is considered to be applicable to larger LCDs for various applications such as smartphones, automotive navigation systems, and mobile internet devices.