Editing Keyboard technology (section)

=== Optical ===
Optical switch technology was introduced in 1962 by Harley E. Kelchner for use in a typewriter machine with the purpose of reducing the noise generated by typewriter keys.

An optical keyboard technology utilizes [[Light-emitting diode|light-emitting devices]] and [[Photoelectric sensor|photo sensors]] to optically detect actuated keys. Most commonly the emitters and sensors are located at the perimeter, mounted on a small [[Printed circuit board|PCB]]. The [[light]] is directed from side to side of the keyboard interior, and it can only be blocked by the actuated keys. Most optical keyboards require at least two beams (most commonly a vertical beam and a horizontal beam) to determine the actuated key. Some optical keyboards use a special key structure that blocks the light in a certain pattern, allowing only one beam per row of keys (most commonly a horizontal beam).

The mechanism of the optical keyboard is very simple – a light beam is sent from the emitter to the receiving sensor, and the actuated key blocks, [[Reflection (physics)|reflects]], [[Refraction|refracts]] or otherwise interacts with the beam, resulting in an identified key.

A major advantage of optical switch technology is that it is very resistant to moisture, dust, and debris because there are no metal contacts that can corrode.

The specialist [[DataHand]] keyboard uses optical technology to sense keypresses with a single light beam and sensor per key. The keys are held in their rest position by [[magnet]]s; when the magnetic force is overcome to press a key, the optical path is unblocked and the keypress is registered.