The working principle and composition structure of the key switch

The key switch has the advantages of small contact resistance load, accurate operating force error, and diversified specifications. It is widely used in equipment and white goods. Because of the environmental conditions of the key switch (elastic force with pressure less than 2 times/environmental temperature and humidity conditions and electrical performance), large equipment and high-load buttons are directly replaced by conductive rubber or dome switch hardware shrapnel, such as medical equipment, TV. machine remote control, etc. So do you know how key switches work?

Key switch principle
The working principle of the key switch is easy to understand. To put it bluntly, it is like this: there is an electromagnet adsorption device inside. Turn the circuit on or off. In this way, the functions of remote control of the line are realized.
In fact, the key switch is a button, which is usually used to connect and disconnect the control circuit. The key switch is a low-voltage electrical appliance that issues commands in electric drag. , used to manually issue control signals to control contactors, relays, electromagnetic starters, etc. Its characteristic is that it is installed in the machines and instruments that are in progress. Most of the time, it is in the position of the initial free state. It is only converted to the second state (position) under the action of external force when the external force is removed. , due to the action of the spring, the switch returns to the initial position.
When the button is not affected by external force (ie static state), the opening and closing state of the contact is divided into the start button (ie the normally open button), the stop button (ie the normally closed button) and the compound button (ie the normally open and normally closed contacts are combined as integrated button). For the start button, the contacts are closed when the button cap is pressed, and the contacts are automatically disconnected and reset when released; the opposite is true when the button is stopped, the contacts are separated when the button cap is pressed, and the contacts are automatically closed and reset when released. The composite key is that when the key cap is pressed, the bridge-type moving contact moves downward, so that the normally closed contact is disconnected first, and then the normally open contact is closed; when the key cap is released, the normally open and normally open contacts are closed first. After breaking and resetting, the normally open contact is closed and reset again.

Key Switch Structure
The key switch first appeared in Japan. In order to better satisfy the operating process force specification, it is necessary to apply pressure to the switch when using the tact switch, and then perform the functions of connection and disconnection. In the case of everyone logging off the pressure, the flick of the switch will turn off. The internal structure of the tact switch relies on the metal composite spring sheet to maintain the bearing capacity, and perform the connection and sealing function. So what is the composition of the key switch?

The key switch is generally composed of a handle, a slide plate, a movable contact piece, a fixed terminal, a compression spring, a shell, etc. It controls the movable contact and the fixed terminal by pressing the switch handle Turning on and off of contacts. There are two types of key switches: single key type and multi-key combination type. The single-button key switch is generally used as a power switch in a TV set, and it is divided into a self-locking and self-resetting type (this switch is pressed once to turn on self-locking, and then pressed again to disconnect and reset) and a non-locking type (no lock). Lock, connect when pressed, reset when released) two structures.

The main uses of key switches are color TVs, black and white TVs, audio equipment, video recorders, video cameras, computers, game consoles, fax machines, walkie-talkies, batons, machine tool control devices, Copiers, printers, electronic instruments, meters and other household appliances.

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