Capacitance sensing

Provided by the ASK Keyboard Dictionary

Category: TechnologiesOrigin: Official

Aka/also known as: capacitive sensing, capsense

Capacitance sensing (or simply "capsense") is a form of key-switch sensing that relies on the principle that any two objects can be a capacitor and that the capacitance they can both hold together changes as one part is moved closer or away from the other. This can be used as a rudimentary distance measurement that can be used to tell if a given key-switch is pressed by comparing the measurement against a desired threshold. Capacitive key-switches are known to have a long lifetime and have an inherent n-key rollover (provided the keyboard-to-host interface also supports NKRO). Common implementations include IBM beam spring, IBM capacitive buckling spring, Topre (specifically electrostatic capacitive (EC) sensing), and numerous foam and foil key-switches. Keyboards that make use of capsense are known as simply capacitive keyboards and are generally more expensive to make and buy than ohmic keyboards.


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