Touch-sensitive active-matrix display with liquid-crystal capacitance detector arrays

We present two types of touch in-cell technology for active-matrix liquid crystal displays (AMLCDs) with liquid-crystal capacitance detector arrays embedded in a hydrogenated amorphous silicon (a-Si:H)-based backplane. The scanning method can determine and provide multiple simultaneous touch locations on the basis of the information extracted from each sensing element. On the other hand, the crossing method provides the position information from the coordinate information such that the system complexity and power consumption are expected to be considerably reduced. In both cases, by limiting the operation of sensors to the subthreshold region, we expect that the degradation of a-Si:H thinfilm transistors (TFTs) will be suppressed and reliability will be ensured. Their relatively simple architecture enables the proposed touch-panel function to be readily integrated within large-area displays. Copyright © 2010 The Japan Society of Applied Physics.