Key switches work by using pressure from pressing a key to complete an electrical circuit, signaling the input to a device.
At its core, a key switch translates a physical press into an electrical signal that a computer or other device can understand. One common method, described in the provided reference, involves rubber domes.
The Rubber Dome Mechanism
This type of switch relies on small, flexible rubber domes. Each dome has a crucial component: a hard carbon center on its underside.
Here's a breakdown of the process:
- The Key Press: When you press down on a key, a mechanism beneath the keycap, often called a plunger, pushes downwards.
- Dome Compression: The plunger presses directly against the rubber dome situated below it. The flexible dome compresses under this pressure.
- Circuit Completion: As the dome is pushed down, the hard carbon center located on the underside of the dome makes contact with a flat, hard surface beneath the key matrix. This surface typically contains electrical contacts.
- Signal Generation: The contact between the carbon center and the surface completes an electrical circuit. This completed circuit sends a signal indicating that the specific key has been pressed.
- Sustaining the Signal: The circuit remains complete, and the signal continues, as long as the key is held down and the carbon center maintains contact.
- Resetting: When the pressure is released, the rubber dome springs back to its original shape, lifting the carbon center away from the surface and breaking the circuit, thus ending the signal.
This simple yet effective mechanism is widely used due to its reliability and cost-effectiveness.
