4 e 5 wire
4 wire touch panels: technologies & theory
The 4-wire resistive touch screen is the preferred solution for low cost applications. It consists of a conductive bottom layer (ITO Glass or Film) and a conductive top layer (ITO Film). The two layers are suspended by lots of very small spacer dots. When a certain point is touched, the top layer contacts the bottom layer and a voltage charged by the controller is applied to the bottom layer's electrodes. The coordinate X axis of the touched point can be detected by measuring the voltage value through the top ITO layer and the coordinate Y axis of the touched point can be detected in the same way by changing voltage input to the bottom layer's electrodes. These are rated to 1 million actuations.
5 wire touch panels: technologies & theory
The operation of the 5-wire is very similar to the 4-wire. The difference is that the switching of the current is pulsed through the bottom layer at the four corners, with the top layer, or 5th wire, being the wiper or voltage probe. The bottom layer is usually glass with a special resistor or frit pattern screened around the perimeter. ITO coatings when applied to glass exhibit superior durability and scratch resistance, as well as excellent resistive stability over time. The linearity of the 5-wire is based upon the bottom ITO glass only. These are rated 15 million to 35 million actuations.