Difference between revisions of "Rubber dome"

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(Contact mechanism: Illustrated and expanded)
(Switched dome with slider illustration to one that is more typical of the switches being described (Topre is not normally called "dome with slider"))
 
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'''Rubber dome''' is a type of keyboard switching technology that is most commonly used on modern keyboards, using collapsible rubber domes to provide resistance and tactility to keys. Most rubber dome keyboards use a membrane contact sheet below the dome to provide electrical switching, but certain rubber dome switches, such as [[Topre switch]]es, use capacitive switching.
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[[File:AppleDesign Keyboard (NMB version) domes from below.jpg|200px|thumb|Membrane rubber domes from the [[AppleDesign Keyboard]]]]
  
==Contact mechanism==
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'''Rubber dome''' is a type of keyboard switching technology that is most commonly used on modern keyboards, using collapsible rubber domes to provide resistance and tactility to keys. Where all the domes are formed from a single sheet of plastic, they may be referred to (especially by Cherry) as '''rubber sheet''' keyboards. In most cases these days, keyboards will be [[rubber dome over membrane]].
[[File:AppleDesign Keyboard (NMB version) domes from below.jpg|250px|thumb|Membrane rubber domes from the [[AppleDesign Keyboard]]]]
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==Description==
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In rubber dome keyboards, the collapsible rubber domes replace the helical [[spring]]s found in other switch types. In some cases, metal springs are still used, including the [[Fujitsu Peerless]] switch and one [[Alps integrated dome]] variant. The domes themselves can be discrete objects, or collectively manufactured as a single sheet of rubber. When discrete, they may be glued down onto the top membrane sheet. A single keyboard may use multiple smaller sheets of domes.
  
Dome switch keyboards use several [[Switch_terminology#Contact_mechanism|contact mechanisms]]:
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Most rubber dome keyboards use a membrane contact sheet below the dome to provide electrical switching, but certain rubber dome switches, such as [[Topre switch]]es, use capacitive switching, and a small number of boards used a [[PCB]].
;Membrane
 
:The "ceiling" of the dome presses two plastic membranes together to connect circuit traces; such keyboards require three membrane layers: upper and lower with exposed conductive traces, and a separator sheet to keep the conductor membranes separated until pairs of contacts are pressed together.
 
;Membrane with carbon-coated domes
 
:The ceiling of the dome is coated with carbon, and this conductive layer connects a pair of circuit traces together when it makes contact with the membrane.
 
;Capacitive
 
:[[Realforce|Topre Realforce]] keyboards use the rubber dome solely as a spring, and switch actuation is performed using capacitance via a 5 cN spring compressed by the dome.
 
;Discrete dome switches
 
:The [[Alps integrated dome]] switch is a discrete, self-contained switch that uses a rubber dome with a conductive pad to connect two metal contacts at the bottom of the switch
 
  
==Gallery==
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A related design is [[buckling rubber sleeve]], which is a rubber collar that sits around the slider and functions largely identically to a dome.
<gallery widths=200px>
 
File:AppleDesign Keyboard (NMB version) domes from above.jpg|Membrane domes from the [[AppleDesign Keyboard]]
 
File:AppleDesign Keyboard (NMB version) membrane sheets.jpg|Membrane sheets and domes from the AppleDesign Keyboard
 
</gallery>
 
  
 
==Varieties==
 
==Varieties==
[[File:Topre HHKB Switch.png|thumb|200px|Topre switch with the slider visible in black]]
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[[File:Tulip 9151B switch .jpg|thumb|200px|[[Tulip 9151B]] dome over slider arrangement]]
  
 
;Plain rubber dome
 
;Plain rubber dome
:A stem is moulded into the keycap that pushes down on the dome; this is the most common variety
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:A slider is moulded into the keycap ([[Keycap_mount|Integrated mount]]) that pushes down on the dome; this is the most common variety
;Domes with sliders
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;Dome with slider
:Similar to a microswitch mechanical, each switch contains its own [[slider]] that presses on the dome, onto which the keycap is [[Keycap_mount|mounted]]; on some keyboards the slider has a standard U mount or Z mount interface and the board will accept keycaps from mechanical keyboards and donate keycaps for mechanical boards. Dome switches with sliders are now uncommon, but this is the form taken by Topre switches
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:Similar to more expensive discrete switches, each key position has a [[slider]] that presses on the dome, onto which the keycap is [[Keycap mount|mounted]]; on some keyboards the slider has a standard Cherry MX mount or Alps mount interface and the board will accept keycaps from mechanical keyboards and donate keycaps for mechanical boards. Dome switches with sliders are now uncommon, but this is the form taken by Topre switches; [[NMB dome with slider]] and [[BTC dome with slider]] are two of the better-known membrane implementations.
 
;Scissors
 
;Scissors
 
:Laptop keyboards introduced the use of [[Scissor switch|scissor-like]] mechanisms to stabilise low travel switches that lack a shaft for the keycap to slide inside
 
:Laptop keyboards introduced the use of [[Scissor switch|scissor-like]] mechanisms to stabilise low travel switches that lack a shaft for the keycap to slide inside
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 +
==Contact mechanism==
 +
Dome switch keyboards use several [[Switch_terminology#Contact_mechanism|contact mechanisms]]:
 +
 +
;Pressure
 +
:The "ceiling" of the dome presses two plastic membranes together to connect circuit traces; such keyboards require three membrane layers: upper and lower with exposed conductive traces, and a separator sheet to keep the conductor membranes separated until pairs of contacts are pressed together. This is the most common type of [[rubber dome over membrane]] keyboard.
 +
;Conductive
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:The ceiling of the dome is coated with carbon, and this conductive layer connects a pair of circuit traces together; the circuit layer can be a membrane, PCB, or (as with the [[Alps integrated dome]] switch), metal contacts.
 +
;Capacitive
 +
:[[Topre Realforce]] keyboards use the rubber dome solely as a spring, and switch actuation is performed using capacitance via a 5 cN spring compressed by the dome.
 +
 +
==Gallery==
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<gallery widths=250 heights=187>
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File:Dell L100 -- opened, 3.jpg|Dome and membrane sheets from a [[Dell L100]] office keyboard
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File:AppleDesign Keyboard (NMB version) domes from above.jpg|Pressure domes from the [[AppleDesign Keyboard]], glued down onto the top membrane sheet
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File:AppleDesign Keyboard (Alps version) rubber domes.jpg|Loose domes
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File:Fujitsu FKB4700-152 -- rubber dome sheet.jpg|Contiguous sheet of domes
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File:Scissor switch (RM).jpg|[[Scissor switch]] with its rubber dome
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File:Alps integrated dome -- Alps mount -- dome.jpg|Conductive domes
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File:Alps integrated dome -- Alps mount -- dome, inside out.jpg|Conductive dome turned inside out to demonstrate the conductive pad
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File:Alps integrated dome -- Alps mount -- dome removed.jpg|Metal contacts in the [[Alps integrated dome]] discrete conductive dome switch
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File:Key Mouse RB-2001-1 -- PCB, top.jpg|Conductive dome PCB, from a Key Mouse RB-2001-1 keyboard<ref>KBTalking — [http://kbtalking.cool3c.com/article/6180 ⊙.⊙非簧片類導電橡膠鍵盤RB-2001-1簡介⊙.⊙]</ref>
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</gallery>
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==References==
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<references>
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</references>
  
 
[[Category:Keyboard terms]]
 
[[Category:Keyboard terms]]
[[Category:List of all keyboard switches]]
 
[[Category:Rubber domes]]
 

Latest revision as of 00:47, 26 February 2017

This article is a stub. You can help Deskthority by expanding it.

Membrane rubber domes from the AppleDesign Keyboard

Rubber dome is a type of keyboard switching technology that is most commonly used on modern keyboards, using collapsible rubber domes to provide resistance and tactility to keys. Where all the domes are formed from a single sheet of plastic, they may be referred to (especially by Cherry) as rubber sheet keyboards. In most cases these days, keyboards will be rubber dome over membrane.

Description

In rubber dome keyboards, the collapsible rubber domes replace the helical springs found in other switch types. In some cases, metal springs are still used, including the Fujitsu Peerless switch and one Alps integrated dome variant. The domes themselves can be discrete objects, or collectively manufactured as a single sheet of rubber. When discrete, they may be glued down onto the top membrane sheet. A single keyboard may use multiple smaller sheets of domes.

Most rubber dome keyboards use a membrane contact sheet below the dome to provide electrical switching, but certain rubber dome switches, such as Topre switches, use capacitive switching, and a small number of boards used a PCB.

A related design is buckling rubber sleeve, which is a rubber collar that sits around the slider and functions largely identically to a dome.

Varieties

Tulip 9151B dome over slider arrangement
Plain rubber dome
A slider is moulded into the keycap (Integrated mount) that pushes down on the dome; this is the most common variety
Dome with slider
Similar to more expensive discrete switches, each key position has a slider that presses on the dome, onto which the keycap is mounted; on some keyboards the slider has a standard Cherry MX mount or Alps mount interface and the board will accept keycaps from mechanical keyboards and donate keycaps for mechanical boards. Dome switches with sliders are now uncommon, but this is the form taken by Topre switches; NMB dome with slider and BTC dome with slider are two of the better-known membrane implementations.
Scissors
Laptop keyboards introduced the use of scissor-like mechanisms to stabilise low travel switches that lack a shaft for the keycap to slide inside

Contact mechanism

Dome switch keyboards use several contact mechanisms:

Pressure
The "ceiling" of the dome presses two plastic membranes together to connect circuit traces; such keyboards require three membrane layers: upper and lower with exposed conductive traces, and a separator sheet to keep the conductor membranes separated until pairs of contacts are pressed together. This is the most common type of rubber dome over membrane keyboard.
Conductive
The ceiling of the dome is coated with carbon, and this conductive layer connects a pair of circuit traces together; the circuit layer can be a membrane, PCB, or (as with the Alps integrated dome switch), metal contacts.
Capacitive
Topre Realforce keyboards use the rubber dome solely as a spring, and switch actuation is performed using capacitance via a 5 cN spring compressed by the dome.

Gallery

References