They have one-piece plastic keytop/switch plungers which press down on a membrane to actuate a contact in an electrical switch matrix.ĭome-switch keyboards are a hybrid of flat-panel membrane and mechanical-switch keyboards. Although used in the early days of the personal computer (on the Sinclair ZX80, ZX81 and Atari 400), they have been supplanted by the more tactile dome and mechanical switch keyboards.įull-travel membrane-based keyboards are the most common computer keyboards today. They are often used in harsh environments where water- or leak-proofing is desirable. Therefore, devices using these issue a beep or flash a light when the key is pressed. Generally, flat-panel membrane keyboards do not produce a noticeable physical feedback.

This indicates to the computer or keyboard control processor that a particular button has been pressed. When the user pushes down at a particular position, their finger pushes the front layer down through the spacer layer to close a circuit at one of the intersections of the grid. When placed together, the stripes form a grid. The back layer has conductive stripes printed perpendicularly to those of the front layer. Under this it has a spacer layer, which holds the front and back layer apart so that they do not normally make electrical contact. The top layer has the labels printed on its front and conductive stripes printed on the back. A common design consists of three layers. There are two types of membrane-based keyboards, flat-panel membrane keyboards and full-travel membrane keyboards:įlat-panel membrane keyboards are most often found on appliances like microwave ovens or photocopiers. Plug and play technology means that its 'out of the box' layout can be notified to the system, making the keyboard immediately ready to use without need for further configuration unless the user so desires. The modern keyboard also includes a control processor and indicator lights to provide feedback to the user (and to the central processor) about what state the keyboard is in. Some newer keyboard models use hybrids of various technologies to achieve greater cost savings or better ergonomics. Virtual keyboards on touch screens have no physical switches and provide audio and haptic feedback instead. 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). Computer alphanumeric keyboards typically have 80 to 110 durable switches, generally one for each key. Among the more important of these is the switch technology that they use.

The technology of computer keyboards includes many elements. Keyboard construction, in four layers, of a typical notebook computer keyboard

Computer keyboard that lights up