Introduction to the Specific Structure of Key Switch
Release time：2019-08-24 Clicks： Click
What is the specific structure of the key switch? Today we will give you a detailed introduction.
The structure of the key switch is composed of a button cap, a reset spring, a fixed contact, a movable contact, a shell and a support connecting rod. Button is not subject to external force (i.e. static) when the contact split and close state, divided into start button (i.e. normally open button), stop button (i.e. normally closed button) and compound button (i.e. normally open and normally closed contact combination as one of the buttons). For the startup button, the contact closes when the button cap is pressed, and automatically opens and resets when the button cap is loosened; on the contrary, the contact is separated when the button cap is pressed, and automatically closes and resets when the button cap is loosened. Compound button is when the button cap is pressed, the bridge type movable contact moves downward, so that the normally closed contact is disconnected before it is closed; when the button cap is loosened, the normally open contact is first broken and reset, then the normally open contact is closed and reset.
Principle, structure, classification and model description of key switch
Next, we will introduce in detail what kind of keyboard switches are. Although we have touched a lot of keyboard switches in our daily life, are they all similar to each other and feel almost the same to us? In fact, although the appearance looks similar, their roles or categories may be quite different, so the following will give a detailed description of the categories in the end:
Key switches are classified according to their use and structure of contacts:
1. Frequent open contact (moving contact): refers to the original state (electrical appliances are not subject to external force or coil is not electrified), fixed contact and movable contact in a separate state of contact.
2. Normally closed contacts (dynamic broken contacts): refers to the contacts in the closed state between fixed contacts and movable contacts in the original state (electrical appliances are not subject to external forces or coils are not energized).
3. Keyboard switch is usually opened (operated) and the contacts are disconnected when not pressed. When pressed, the contacts are closed and connected. When loosened, the key switch is reset and disconnected under the action of reset spring. In the control circuit, the often open button is often used to start the motor, also known as the start button.
4. The normal-closed (dynamic-off) key switch is opposite to the normal-open key switch. When pressed at the end, the contact is closed, and when pressed, the contact is disconnected. When the hand is released, the key switch is reset and closed under the action of reset spring. Normally closed button is often used to control motor parking, also known as self-reset button.
5. Compound key switch: A key switch that combines the normal open and normal closed key switches, i.e. a constant closed contact and a constant open contact. When not pressed, the normally closed contacts are closed and the frequently opened contacts are disconnected. When pressing the button, the normally closed contacts are first disconnected and then closed, which can be regarded as self-locking buttons. When the button switch is loosened, under the action of reset spring, the normally open contacts are first disconnected, and then the normally closed contacts are closed. The compound button is used in the interlocking control circuit.