The key switch mainly refers to the light touch key switch, also known as the light touch switch. The key switch is an electronic switch, which belongs to the category of electronic components. It first appeared in Japan [called: sensitive switch]. When used, the switch function is closed and turned on by applying pressure to the switch operating direction to meet the conditions of the operating force. When the pressure is on, the switch is disconnected, and its internal structure is realized by the change of the force of the metal shrapnel.
The key switch is a man-made operation and has a control element that can be automatically reset by the spring through the operation. It is a common master device in the control circuit. Then, in the continuous development and evolution after this, various specifications of products with indicator lights, key holes, and emergency braking functions have been added, but their essential structure and operating principle have not changed. The main discussion in this article is the button The structure and working principle of the switch.
The four pins of the key switch are normally open and normally closed, and which two are used depends on the requirements of the circuit. initiate. When the button is not pressed, it is called normally closed, and when the button is pressed, it is disconnected. When the button is not pressed, it is called normally open, and when the button is pressed, it is connected. Of course, it is measured by the ohm gear (Ω) of the multimeter.
There are many structural varieties of key switches, which can be divided into ordinary button type, mushroom head type, self-locking type, self-resetting type, rotary handle type, indicator type, lamp symbol type and key type, etc. Buttons, three buttons and different combinations are generally made of building blocks, which are composed of key caps, reset springs, bridge contacts and shells, etc., generally made of composite type, with a pair of normally closed contacts and normally open contacts. Some products can increase the number of contact pairs by connecting multiple components in series. There is also a self-restraint button, which can automatically maintain the closed position after being pressed, and can be opened only after the power is turned off.
The key switch can complete basic control such as start, stop, forward rotation, speed change and interlock. Generally, each key switch has two pairs of contacts. Each pair of contacts consists of a normally open contact and a normally closed contact. When the button is pressed, the two pairs of contacts act together, the normally closed contact is disconnected, and the normally open contact is closed.
Key switch application
The key switch has the advantages of small contact resistance load, accurate operating force error, and diversified specifications. It has been widely used in electronic equipment and white goods, such as audio and video products, digital products, remote controls, communication products, and household appliances. , Security products, toys, computer products, fitness equipment, medical equipment, money detector pens, laser pen buttons and so on. 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.
