Editing Force (section)

==Terminology==
Switches are commonly described with a single force figure, and it's not always clear which part of the force curve this figure describes. Also, the feel of a switch is characterised by the change in force, within which there are a number of clearly-defined points. For tactile switches (including clicky switches), the figures cited by the community typically refer to the tactile force, as this is the most readily measured force.
<br><br> <!-- Force a blank line above the image. Stupid wiki. -->

[[File:Force graph--annotated.svg|centre|500px]]

;Preload
:The force required to begin depressing a key. This force arises from partial compression of the spring by the switch at rest: when a switch is assembled, the spring is compressed by a certain amount by the space inside the switch (with the slider fully raised) being shorter than the spring. Preload can be seen by the force curve having a ''y'' intercept greater than zero. Preload prevents keys from having a loose, slack feel, especially for people who rest their fingers on the keys. Preload is described and illustrated in European patent [http://www.google.com/patents/EP0104956B1 EP0104956B1] for [[Olivetti dome with slider]].
;Tactile force
:For tactile switches (including clicky but not linear switches) the force required to overcome the tactile peak in the force curve. This force is frequently mechanically unrelated to the operation of the switch contacts and serves only to provide feedback to the operator. Switch actuation is typically intended to occur just after this point, when the force level drops off, using the momentum gained to propel the slider forward to the actuation point.
;Actuation force
:The force required to [[actuation|actuate]] the switch, i.e. to cause it to register a key press. In linear switches, this simply sets the amount of pretravel required, i.e. how far the switch must be pressed for it to register. This figure is not particularly relevant for tactile switches, but care must be taken to not mistake this force for the tactile force. For example, [[Cherry MX Blue]] switches are widely cited as 50 cN, but this is the actuation force: the tactile force for MX Blue is 60 cN. Cherry MX switches are widely described in terms of their actuation force, not the tactile force, possibly to maintain a consistency between the tactile and linear switches as the linear switches have no notion of tactile force.
;Terminal force
:The force exerted by the switch at full travel; for some switches (especially [[Cherry MX Clear]]) this can be much higher than the actuation force.
;Peak force
:The highest force encountered in the [[Switch_terminology#Key_travel|travel]] of the switch, before the switch bottoms out. For linear switches, this is necessarily the force required to reach the end of the switch's travel. For tactile switches, it depends on which of the tactile force and terminal force is higher.

[[Category:Keyboard terms]]