Resistive Touch Screens
Figure 1 below shows the construction of a typical analog-resistive touch screen. This type of touch screen is very commonly used in portable computers. (Note: Numbers in parentheses in the following paragraphs refer to the layer ID numbers on the right side of each Figure.)
A resistive touch screen consists of solid glass substrate (6) coated with indium tin oxide (ITO) (3), a transparent conductor. A flexible polyester (PET) membrane (2) also coated with ITO (3) is suspended above the glass substrate. Transparent spacer dots (5) keep the two conductive surfaces apart, forming an air gap (4). A hardcoat (1) makes the surface of the polyester membrane more resistant to wear. The force of a touch collapses the membrane, causing contact between the conductive surfaces. Electronics measures the resistance along the edges in two dimensions and calculates the point of touch.