What is a touch screen and how does it work?
Designers of consumer products can choose their panel from various touch-screen technologies. Most of the panel technologies available use resistive, capacitive, surface acoustic wave (SAW), or infrared (IR) techniques. The most popular touch screen on the market is resistive because it is inherently stable and affordable. There are 4-wire, 5-wire, 7-wire, or 8-wire resistive touch screens. The most common resistive touch screens have four wires. The layers of a 4-wire resistive touch screen panel, from top to bottom, are a rectangular, flexible top layer; a transparent, conductive coated layer (the conductive coating is usually made of indium tin oxide or ITO); air-gap and isolation spacers; another transparent ITO layer; and finally, a stable layer. In Figure 2a, yellow outlines the top ITO layer, green outlines the second ITO layer, and blue outlines the bottom stable layer of a 4-wire touch screen panel.
