A equivalent schematic of touch panel can be
found in figure 2.2b where X+, X- correspond to the plus and minus pole of
X-layer and Y+, Y- correspond to the plus and minus pole of the Y-layer. RT
illustrates the resistance between the two layers and its value is dependent
of were the panel is pressed, Rtl + Rtr form the total resistance in the top
layer and Rbl + Rbr for the bottom layer.