There are many types of button switches, including ordinary button type, mushroom head type, self-locking type, self resetting type, rotary handle type, indicator type, symbol type with light and key type. There are single button, double button, I button and different combination forms. Generally, it adopts ponding structure, which is composed of button cap, return spring, static contact, moving contact and shell. It is usually made into composite type, with a pair of normally closed contacts and normally open contacts. Some products can increase the number of contacts through the series connection of multiple elements. There is also aself-contained button, which can automatically maintain the closed position after being pressed, and can only be opened after power failure.

When the button switch is not pressed, the moving contact is connected with the fixed contact above, which is called normally closed contact. At this time, the moving contact is disconnected from the static contact below. This pair of contacts is called normally open contact: press the button, the normally closed contact is disconnected and the normally open contact is closed; Release the button to restore the original working state under the action of the return spring.