A Touch Sensitive Liquid Crystal Display with Embedded Capacitance Detector Arrays

We present a new touch sensitive liquid crystal display (LCD) with embedded capacitance sensor arrays which incorporate hydrogenated amorphous silicon (a-Si: H) thin-film transistors (TFTs) and coupling capacitors. The proposed system utilizes the change in the capacitance of liquid crystal for touch-panel operation and provides the location of the finger touch by obtaining the intersection point for the horizontal and vertical positions, thereby obviating the need for image capturing and real-time image processing. By limiting the operation of the TFTs to the subthreshold region, we can suppress the degradation of a-Si: H TFTs. Due to the simple architecture, the proposed touch-panel function can be readily integrated within large-area displays.