The key switch mainly refers to the light-touch key switch, also known as the touch switch. The key switch is an electronic switch and belongs to electronic components. It first appeared in Japan. When in use, press the switch in the operating direction to meet the operating force. When the pressure is released, the switch is closed, and its internal structure is switched on and off through the stress change of the metal spring. The key switch consists of an insert, a base, an elastic sheet, a button and a cover. A layer of polyimide film is added to the elastic sheet of the waterproof key switch.

1. Function of the push button switch. A push button is a control switch operated by a certain part of the human body (usually a finger or palm) and reset by spring energy storage. It is one of the commonly used main command devices. Generally speaking, the push button switch does not directly control the on and off of the main circuit (high current circuit), and the current allowed by its contacts generally does not exceed 5A, so basically it sends command signals in the control circuit (low current circuit) to control contactors, relays and other electrical appliances, which then control the on and off of the main circuit, function conversion or electrical interlocking.

2. Structural principle and symbol of the push button switch. Usually, the push button switch consists of a button cap, a static contact, a bridge-type moving contact, a reset spring, a support rod and a shell. When the button is not subjected to external force (i.e. static), the on and off state of the contact can be divided into a start button (i.e. a dynamic closing button), a stop button (i.e. a dynamic breaking button) and a compound button (i.e. a button that combines the dynamic closing and dynamic breaking contacts into one).

3. Key switch structure code: K-open type, embedded in the operation panel; h-protective type, with protective shell, can prevent internal parts from being damaged by machinery or people accidentally touching live parts.

4. Button model and meaning: S-waterproof, with sealed shell to prevent rainwater intrusion; F-corrosion-resistant type, can prevent corrosive gas from entering; J-emergency type, with a large red mushroom button (protruding outward) for emergency power off; X-knob type, operated by rotating the knob, with on and off positions; Y-key operation type, plug-in operation, can prevent misoperation or special operation; D-cursor button, equipped with a signal light, also used as a signal indication.

5. Selection of key switches: 1. Select the type of button according to the occasion and specific purpose. For example, the button embedded in the operation panel can be opened; select the cursor type to display the working status; key operation should be used in important occasions to prevent misoperation by personnel; anti-corrosion type should be used in places with corrosive gases. 2. Select the color of the button according to the working status indication and work requirements. For example, the start button can be white, gray or black, preferably white or green; the emergency stop button should be red; the stop button can be black, gray or white, preferably black or red. 3. Select the number of buttons according to the needs of the control circuit, such as single button, double button and triple button.