If you’ve come across touch switches, you might be wondering how they work. Nearly all electronic devices contain one or more switches. Switches are the foundation that allows electrical devices to function as intended. They consist of a conducting path that can be opened or closed. Touch switches contain a conductive path as well, but they feature a unique touch-based design that distinguishes them from other switches.
An Introduction to Touch Switches
A touch switch is a type of electrical switch that, as the name suggests, requires physical contact or “touch” to operate. You’ll often find touch switches on free-standing lamps and light fixtures as well as computers. Many touchscreen devices also contain touch switches embedded in their display interface.
Pressing a touch switch will cause it to respond by opening or closing the circuit. When you press your finger against a touch switch, it will respond by opening or closing the circuit.
How Touch Switches Work
All touch switches work by opening or closing a circuit in response to a touch command. With that said, the mechanism a touch switch uses varies depending on the type of touch switch. There are three primary types of touch switches: capacitive, resistance and piezo, each of which use a different mechanism.
Capacitive touch switches work by measuring capacitance — just like their capacitive touchscreen counterparts. They emit a uniform electrostatic field across the top layer. Touching this layer with your bare finger or any other conductive object will draw some of its electrostatic charge to your body, resulting in a reduction of capacitance. The capacitive touch switch will then respond by opening or closing the circuit.
Resistive touch switches work by creating “resistance” between two electrodes. They contain a top electrode and a bottom electrode that are separated. Touching the button will push the two electrodes together and, therefore, complete the circuit.
Piezo switches, on the other hand, rely on the properties of piezo ceramics to open and close the circuit. They aren’t as common as capacitive or resistive touch switches, but they offer a viable switching solution for countless commercial and consumer switching applications.
Touch switches work in different ways, depending on their respective technology. There are capacitive, resistive and piezo touch switches. All three types of technologies respond to touch commands by opening or closing a circuit. With that said, capacitive, resistive and piezo touch switches use different underlying mechanisms to perform this operation.