Xah Lee, , …,
This page is a guide of computer keyboard key switch mechanisms.
Most keyboard key mechanisms today uses rubber dome. e.g. basically all labtop keyboard and Microsoft ＆ Logitech keyboards. Rubber dome type is cheap to make, but is not as good as other mechanisms that uses a spring, because the tactile feedback is not precise, kinda wobbly. Usually what made it worse is the cheap key housing mechanism that goes with it. (ever had squeaky keys that make ugly noises and sometimes stuck midway due to friction?)
Scissor-switch is found in labtop computers, starting around ≈2002. It is still rubber dome, but is enhanced by a scissor-like mechanism above the rubber membrance.
This is most famous as used by IBM Model M keyboard, and loved by many computer geeks.
This tech is old. If you want the tactile feel of the click, you can get from keyboards usings Cherry Blue switch. But if you really want buckling-spring, you can buy it from Unicomp. See bottom of: The Idiocy of Hacker Keyboards.
Cherry Corporation of Germany makes mechanical switches used in many high-end keyboards. Their switchs are known as Cherry MX switches. There are several different models with different properties of feel. These models are color coded. They are:
The “no click” types are good for gaming when a key needs to be pressed repeatedly quickly. (e.g. firearm trigger)
The “clicky” types are good fo intensive typing.
Another type of expensive switch is by capacitance. In particular, one made by Topre Corporation, of Japan.
Topre key switch as famously used in Happy Hacking Keyboard (only in models labeled “Professional”).
Here's a quick list of keyboards with mechanical switches. They typically start at $70. Ergonomic ones with fancy shapes usually starts at $200.
Note: Microsoft or Logitech keyboards do not use mechanical switches, even expensive ones.
Another issue commonly discussed with key mechanism is key ghosting and n-key rollover. Basically, it means how many keys can be pressed simultaneously. See: Keyboard Ghosting; How Many Keys Your Keyboard Can Take?.