38.4: 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 ofa‐Si:H TFTs. Due to the simple architecture, the proposed touch‐panel function can be readily integrated within large‐area displays.