Editing Lock key

A '''lock key''' is a key on a keyboard which typically toggles the behaviour of multiple keys.

==Description==
When the key is pressed, the selected lock mode is engaged, and the affected keys will exhibit different behaviour. Pressing the lock key a second time will disengage the lock state. [[Scroll lock]] is an example of a lock state that does not affect the behaviour of the keyboard.

'''See:''' [[:Category:Lock keys|List of lock keys]]

==Status LEDs==
[[File:Lock LED cluster.jpg|200px|thumb|Typical LED cluster of a mid-90s keyboard]]

Each lock state typically has an associated [[light-emitting diode|LED]] on the keyboard. Early IBM PC keyboards lacked these LEDs; support for two-way communication with LED control was introduced with the [[AT keyboard interface]], and IBM AT keyboards featured a bank of LEDs at the top right. [[IBM Model M|Model M]] and [[IBM Model F|Model F]] keyboards without status LEDs are the older models that use the [[XT keyboard interface]].

The number of lock keys varies by keyboard. [[Numeric keypad]]s may feature a single num lock LED; comparatively, [[tenkeyless]] keyboards will lack the num lock LED, just as they lack the numeric keypad. Some keyboards such as the [[Chicony KB-5591]] have extra lock LEDs, for example cursor lock. Typical PC keyboards feature [[num lock]], [[caps lock]], and [[scroll lock]] LEDs at the top right in that specific order; the status LED order has never changed in over twenty-five years.

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===Integrated LEDs===
[[File:Integrated lock key.jpg|200px|thumb|Integrated LED in the [[Matias Tactile Pro 3|Tactile Pro 3]]]]

On some keyboards, the status LEDs are integrated directly into the keys. The LED will be integrated into the switch or placed directly under or beside the switch, and the keycap will have a window to let the light through.

Several Cherry switch families including [[Cherry MX]] and [[Cherry M8]] support integrated LEDs. [[Matias switch]]es have transparent shells to permit light to shine through from an LED under the switch, as the Alps switch design does not have space to support an LED without removing the [[click leaf]]; [[Alps SKCL/SKCM series|Alps SKCL/SKCM]] and [[Alps SKBL/SKBM series|SKBL/SKBM]] switches and clone families do support integrated LEDs, and these switches are always linear.

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==Alternate action switches==
{{Main|Alternate action}}
[[File:Futaba vintage lock switch in latched state.jpg|200px|thumb|[[Futaba linear lock|Futaba]] latching lock key in latched state]]

'''Alternate action''' switches cycle between open and closed each time they are pressed. Typically, the slider latches in a lower position when the switch is closed, and returns to its fully raised position when the switch is pressed again.

Alternate action provides both a tactile and visual alternative to status LEDs: the lock state can be felt based on the key position (raised or lowered) and this state can also be observed by the operator. Illuminated alternate action switches do exist, but in keyboards they are typically not fitted with an LED.

Apple were one of the most prominent companies to alternate action switches, even with the membrane-based [[Apple Keyboard II]]. Cherry manufactured the [[Cherry MX Lock|MX Lock]] alternate action switch, but these are seldom found in Cherry MX keyboards.

==Gallery==
<gallery widths=250px heights=187>
File:Linear XM switch with LED.jpg|[[Xiang Min KSB series|Xiang Min KSB-LE]] with integrated LED
File:Key Tronic 110.jpg|Key Tronic key with a separate LED
File:Apple M0116 Caps Lock disengaged.jpg|[[Alps lock]] switch in disengaged (open) state
File:Apple M0116 Caps Lock engaged.jpg|Alps lock switch in engaged (closed) state
File:Alps lock disassembled.jpg|Alps lock switch showing the latching mechanism
File:BBC Micro keyboard.jpg|Vintage computer with proprietary lock keys and status LEDs
</gallery>

==References==
<references />

[[Category:Keyboard terms]]