Keyboard technology

Virtual keyboards, which are mostly accessed via a touchscreen interface, have no physical switches and provide artificial audio and haptic feedback instead.

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 the need for further configuration, unless the user so desires.

This also enables manufacture of generic keyboards for a variety of language markets, that differ only in the symbols engraved on the keytops.

The rubber dome serves a dual purpose: it acts as a tactile return spring and provides a soft surface to transfer force onto the top membrane.

Rubber dome over membrane keyboards became very popular with computer manufacturers as they sought to reduce costs while PC prices declined.

A common, compact variant of rubber dome over membrane is the scissor-switch, based on the scissors mechanism.

Polydome tactile membrane switches use polyester, or PET, and is formed to create a stiff plastic dome.

[2] Non-tactile flat-panel membrane keyboards have little to no keypress feel and often issue a beep or flash of light on actuation.

This type of keyboard can take advantage of the thin flexible plastic membranes, but still pose the risk of damage.

Because these keyboards are typically made of silicone, they unfavorably tend to attract dirt, dust, and hair.

This type of switch are usually composed of a housing, a spring, and a slider, and sometimes other parts such as a separate tactile leaf or clickbar.

Hot-swap sockets can allow users to change different switches out of the keyboard without having the tools or knowledge required to solder.

The sensor tells enough about the distance of the keypress to allow the user to adjust the actuation point (key sensitivity).

Because they require no physical contact for actuation, Hall-effect keyboards are extremely reliable and can accept millions of keystrokes before failing.

They are used for ultra-high reliability applications such as nuclear power plants, aircraft cockpits, and critical industrial environments.

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.

This type of keyboard is portable enough to be easily used with PDAs and cellphones, and many models have retractable cords and wireless capabilities.

[12] IBM's Model F keyboard series was the first to employ buckling spring key-switches, which used capacitive sensing to actuate.

The original patent was never employed in an actual production keyboard but it establishes the basic premise of a buckling spring.

[15] Optical character recognition (OCR) is preferable to rekeying for converting existing text that is already written down but not in machine-readable format (for example, a Linotype-composed book from the 1940s).

OCR technology has already reached an impressive state (for example, Google Book Search) and promises more for the future.

For certain uses (e.g., transcription of medical or legal dictation; journalism; writing essays or novels) speech recognition is starting to replace the keyboard.

However, the lack of privacy when issuing voice commands and dictation makes this kind of input unsuitable for many environments.

Software keyloggers work on the target computer's operating system and gain unauthorized access to the hardware, hook into the keyboard with functions provided by the OS, or use remote access software to transmit recorded data out of the target computer to a remote location.

Enabling a firewall does not stop keyloggers per se, but can possibly prevent transmission of the logged material over the net if properly configured.

Neal O'Farrell, executive director of the Identity Theft Council, revealed to InformationWeek that "More than 25 years ago, a couple of former spooks showed me how they could capture a user's ATM PIN, from a van parked across the street, simply by capturing and decoding the electromagnetic signals generated by every keystroke," O'Farrell said.

[19] The risks of injuries can be reduced by taking frequent short breaks to get up and walk around a couple of times every hour.

[21] Some adaptive technology ranging from special keyboards, mouse replacements and pen tablet interfaces to speech recognition software can reduce the risk of injury.

By using a touchpad or a stylus pen with a graphic tablet, in place of a mouse, one can lessen the repetitive strain on the arms and hands.

Keyboard construction of a typical notebook computer keyboard, in four layers
A typical membrane assembly
Exploded view of a typical rubber dome over membrane design
Scissor switch mechanism
Atari 400 keyboard
Most keyboards are rigid, but this keyboard is flexible.
Cherry MX Blue (left) and disassembled Cherry MX Brown (right)
Cherry MX switch contacts
Reed switch with reed module removed
Topre electrostatic capacitive switch
RAFI RS 76 C 010 hall effect switch fully disassembled
Illustration from the original buckling spring U.S. patent 4,118,611 , issued to IBM in 1978
A classic full-size Model M keyboard with Spanish ISO key layout
Snapshot of switch bounce on an oscilloscope . The switch bounces between on and off several times before settling.
A close-up of a keyboard matrix circuit printed onto a flexible transparent PET sheet
On-screen keyboard controlled with the mouse can be used by users with limited mobility.