There are many types of touch switches, and now the most common ones are as follows:

1. Mechanical touch switch: It is still a traditional button switch, but after improvement, the stroke is short and the required distance to press is small.

2. Dual conductive switch: The front end is composed of two electrode plates, and the inside is an amplification circuit that amplifies the current formed in the two electrode plates when touched by fingers, and drives the subsequent circuit to achieve switching or control functions.

3. Single chip trigger switch: The front end only has one electrode, and after the hand touches it, the human body acts as an antenna to receive electromagnetic waves absorbed from space and send them into the circuit through the electrode. The circuit is a high gain amplification circuit that can amplify very small signals and use this signal to trigger the subsequent circuit to achieve switching or control functions. Due to the need for high input impedance to amplify very small signals, this type of circuit has weak anti-static ability and is easily damaged by static electricity.

4. Resistance film or conductive film pressure switch: This type of switch is achieved by a three-layer structure, with a support grid sandwiched between the upper and lower conductive plates. This structure is generally used for computer keyboards, which are actually still in the same category as touch switches, but people can hardly feel the stroke.

5. Capacitor touch switch: The capacitor formed by a specially shaped PCB (printed circuit board) is used as the trigger condition for whether to touch or not. Generally, a hard FR-4 substrate is used, and the capacitor contact board made of this material has a small capacitance base, and the capacitance changes significantly after touch, resulting in good results. By using a SLOPE circuit or frequency voltage conversion circuit, the capacitance change can be distinguished, and finally, whether there is finger touch can be determined. This is the most advanced type, which is adopted on IPOD. But it also poses a risk of electrostatic breakdown due to the high impedance of the front end.