Analog resistive is one of the reigning touch technologies, although it’s losing ground to projected capacitive. It probably will remain popular because it is easy to integrate, has a low cost associated with it, and consumes little power. It also works with a variety of touch inputs, and it’s unaffected by dirt, water, light, and most EMI noise.
How Analog Resistive Works:
Resistive touch technologies include 3-wire, 4-wire, 5-wire, 6-wire, and 8-wire. The most common resistive touch technologies are 4-wire and 5-wire. The two technologies offer different benefits; the 4-wire technology offers a lower cost, but the 5-wire one is more durable.
The touchscreen typically consists of a glass layer with an indium tin oxide (ITO) conductive coating on top and a polyester top sheet with a conductive coating on the bottom. The two surfaces are separated by “spacer dots,” glass beads that are silkscreened onto the coated glass. With 5-wire resistive touch technology, a charge is applied to the four corners of the glass layer. When a person touches the top layer, the polyester one, the conductive coating comes into contact with the conductive coating on the glass layer, which closes the circuit. The voltage at the point of contact is then detected and pinpointed by a wire – the fifth wire – that is connected to the polyester sheet.