What Is Keyboard?
The technology of computer keyboards includes many elements. Among the more important of these is the switch technology that they use. Computer alphanumeric keyboards typically have 80 to 110 durable switches, generally one for each key. The choice of switch technology affects key response (the positive feedback that a key has been pressed) and pre-travel (the distance needed to push the key to enter a character reliably). Virtual keyboards on touch screens have no physical switches and provide audio and haptic feedback instead. Some newer keyboard models use hybrids of various technologies to achieve greater cost savings or better ergonomics.
What's under the keys?
Pull a key off the keyboard and you can see roughly how it works. There's a little hole in the plastic base and the keyboard has a long round bar the same shape. When you press the key, the bar pushes down through the hole to touch the contact layers below. Inside the hole, there's a little tiny piece of rubber (you can't see it in this photo) that stops the key moving down and pushes it back up when you release it. This is what gives the spring to the keys.
What's under the keyboard?
Take off the keyboard's bottom panel and you can see how it all works from beneath. You can see the transparent plastic contact layers that detect key presses and (through those layers) you can see the round bars poking the keys down from above. The green rectangle at the top contains three small LEDs that activate the indicator lights for "Num lock", "Caps lock", and "Scroll lock". Notice also the cable running along the inside of the case at the top of the keyboard, which carries electrical signals from the keyboard to your computer's USB port (or PS/2 port on older machines).
How do the keys press down?
Peel back the electrical contact layers and you can see the bottom of the keys and where they press down. Balancing on my fingertip, you can see one of the little rubber pieces that makes the keys bounce up and down. Notice the pattern of electrical tracks on the contact layers. In this photo, we are looking down through the bottom of the keyboard (so the keys are underneath).
How do the contact layers work?
This is the magic part of a keyboard. There are three separate layers of plastic that work together to detect your key presses. Two of them are covered in electrically conducting metal tracks and there's an insulating layer between them with holes in it. The dots you can see are places where the keys press the two conducting layers together. The lines are electrical connections that allow tiny electric currents to flow when the layers are pressed tight to one another by a key moving down from above.
In the photo below, you can see a closeup of the underside of one key—and, if you look closely, just about see how it works. There's one set of electrical connections on the lower sheet of plastic, printed in light gray. The other set is on the upper sheet of plastic and printed in dark gray. The two sheets are kept apart by a clear plastic layer except at the holes, which is where the keys push down to make the two sheets touch.
Are laptops the same?
Laptops have much shallower keyboards because they have to close up tightly. That means the keys are much thinner and, if you pop them off, you'll notice they're often attached in a different way. On this Toshiba keyboard, there's no long bar on the back of the keys. Instead, each key is essentially flat with four little holes on the back that snap onto the four white plastic pegs you see here, holding it in place but allowing it to move up and down. The blue thing in the middle is the "spring" that pushes the key back up when you release it. Underneath all this, the contact layer mechanism is essentially the same.
FOLLOW US ON INSTAGRAM,FACEBOOK AND PINTEREST
DISCLAIMER
The information is provided by Tecquisition for general informational and educational purposes only and is not a substitute for professional legal advice. If you have any feedback, comments, requests for technical support or other inquiries, please mail us by tecqusition@gmail.com.
Comments