Membrane keyboard: Difference between revisions
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{{short description|Type of computer keyboard with pressure pads instead of mechanical keys}} |
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{{Unreferenced|date=December 2009}} |
{{Unreferenced|date=December 2009}} |
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[[Image:Z1013 |
[[Image:Robotron Z1013 membrane keyboard.jpg|thumb|right|320px|Membrane keyboard as used on the East German [[Robotron Z1013]].]] |
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A '''membrane keyboard''' is a [[computer keyboard]] whose "keys" are not separate, [[moving parts]], as with the majority of other keyboards, but rather are |
A '''membrane keyboard''' is a [[computer keyboard]] whose "keys" are not separate, [[moving parts]], as with the majority of other keyboards, but rather are pressure pads that have only outlines and [[symbol]]s printed on a flat, flexible surface. Very little, if any, [[tactile feedback]] is felt when using such a keyboard. |
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Membrane keyboards work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed. These models were used with some early 1980s [[home computer]]s, enjoying wide adoption in consumer electronics devices. The keyboards are quite inexpensive to mass-produce, and are more resistant against dirt and liquids than most other keyboards. However, due to a low or non-existent tactile feedback, most people have difficulty typing with them, especially when larger numbers of characters are being typed. [[Chiclet keyboard]]s were a slight improvement, at least allowing individual keys to be felt to some extent. |
Membrane keyboards work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed. These models were used with some early 1980s [[home computer]]s, enjoying wide adoption in consumer electronics devices. The keyboards are quite inexpensive to mass-produce, and are more resistant against dirt and liquids than most other keyboards. However, due to a low or non-existent tactile feedback, most people have difficulty typing with them, especially when larger numbers of characters are being typed. [[Chiclet keyboard]]s were a slight improvement, at least allowing individual keys to be felt to some extent. |
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Aside from early hobbyist/kit/home computers and some [[video game console]]s, membrane-based [[QWERTY]] keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for [[Personal Digital Assistant|PDA]]s and other pocket computing devices. Smaller, specialised membrane keyboards, typically numeric-and-a-few-control-keys only, have been used in access control systems (for buildings and restricted areas), simple handheld calculators, domestic [[remote control]] keypads, microwave ovens, and other similar devices where the amount of typing is relatively small or infrequent, such as cell phones. |
Aside from early hobbyist/kit/home computers and some [[video game console]]s, membrane-based [[QWERTY]] keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for [[Personal Digital Assistant|PDA]]s and other pocket computing devices. Smaller, specialised membrane keyboards, typically numeric-and-a-few-control-keys only, have been used in access control systems (for buildings and restricted areas), simple handheld calculators, domestic [[remote control]] keypads, microwave ovens, and other similar devices where the amount of typing is relatively small or infrequent, such as cell phones. |
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Modern PC keyboards are essentially a membrane keyboard mechanism covered with an array of [[Keyboard_technology# |
Modern PC keyboards are essentially a membrane keyboard mechanism covered with an array of [[Keyboard_technology#Rubber dome over membrane|dome switch]]es which give positive tactile feedback. |
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== |
== Mechanism == |
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As can be seen from the diagram below, the membrane keyboard basically consists of three layers; two of these are membrane layers containing conductive traces. The center layer is a "spacer" containing holes wherever a "key" exists. It keeps the other two layers apart. |
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The membrane (typically made out of [[Polyethylene terephthalate]] or PET) keyboard consists of three layers: two layers containing traces of [[conductive ink]] and the center layer is a "spacer" containing holes wherever a two conductive "key" pads count touch upon being pressed. The third layer keeps the other two layers separated in order to prevent [[short-circuit]]. |
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| ⚫ | |||
Under normal conditions, the switch (key) is open, because current cannot cross the non-conductive gap between the traces on the bottom layer. However, when the top layer is pressed down (with a finger), it makes contact with the bottom layer. The conductive traces on the underside of the top layer can then bridge the gap, allowing current to flow. The switch is now "closed", and the parent device registers a keypress. |
Under normal conditions, the switch (key) is open, because current cannot cross the non-conductive gap between the traces on the bottom layer. However, when the top layer is pressed down (with a finger), it makes contact with the bottom layer. The conductive traces on the underside of the top layer can then bridge the gap, allowing current to flow. The switch is now "closed", and the parent device registers a keypress. |
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Many applications benefit from the sealed nature of the membrane keypad. Feedback can easily be provided to the user via audible means (e.g. a beep) or visually (lights or via the display itself), or via both means together. For additional wear resistance, a simple, easily replaceable protective clear sheet can be placed in front of the membrane. Membrane keyboards are widely used in consumer electronics, industrial, commercial, scientific and military equipment. |
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Typical applications include; |
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*Industrial controls |
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*Access control systems |
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*Medical equipment |
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*Telecommunications apparatus |
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*Telephone systems |
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*Household appliances |
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*Security systems |
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Source, [http://www.apemswitches.be/1-27757-Membrane-switch-panels.php APEM, Membrane switch panels] |
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[[File:Inside Computer keyboard.jpg|thumb|Internal layers of a modern full-travel computer keyboard; bottom contact layer, spacer layer with holes, top contact layer, then elastomer top layer to provide restoring force to keytops.]] |
[[File:Inside Computer keyboard.jpg|thumb|Internal layers of a modern full-travel computer keyboard; bottom contact layer, spacer layer with holes, top contact layer, then elastomer top layer to provide restoring force to keytops.]] |
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==List of keyboards with membrane interfaces== |
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''QWERTY layouts unless otherwise specified'' |
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* [[Atari 8-bit family|Atari 400]] (full-travel replacement keyboards much like those that came with the Atari 800 were available) |
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* [[Cambridge Z88]] (arguably a mix between a membrane and chiclet keyboard) |
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* [[Elektronika BK-0010]], in early versions (it was a Russian home computer, hence the JCUKEN layout) |
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* [[Magnavox Odyssey²]], also known as the [[Philips]] [[Videopac G7000]] video game console |
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* [[RCA]] [[COSMAC VIP]], a do-it-yourself ([[DIY]]) kit computer with 16-key [[hexadecimal|hex]] keypad |
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* [[VEB Robotron|Robotron]] Z1013, Eastern-German home computer (alphabetical layout) |
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* [[SEGA]] [[SC-3000]], a computer version of an early SEGA game console |
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* [[Sinclair Research|Science of Cambridge]] Microcomputer Kit 14 ([[MK14]]); the initial version had a 20-key extended hex keypad |
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* [[Sinclair ZX80]], a pioneering British home computer that was available as a DIY kit |
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* [[Sinclair ZX81]] (similar to the preceding entry) |
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* [[Speak & Spell (toy)|Speak & Spell]] (ABC layout until 1989) |
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* [[Synertek]] [[SYM-1]], a sibling of the [[MOS Technology|MOS]]/[[Commodore International|CBM]] [[KIM-1]] with a 29-key extended hex keypad |
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* [[Timex Sinclair 1000]] (a U.S. version of the ZX81) |
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==See also== |
==See also== |
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* [[Chiclet keyboard]] |
* [[Chiclet keyboard]] |
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* [[Keyboard technology]] |
* [[Keyboard technology]] |
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==References== |
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{{Empty section|date=June 2013}} |
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==External links== |
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* [http://yanchuen.com/en-GB/factory/membrane-switch Structure of Membrane Keyboards] |
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{{DEFAULTSORT:Membrane Keyboard}} |
{{DEFAULTSORT:Membrane Keyboard}} |
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[[Category:Computer |
[[Category:Computer keyboard types]] |
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Latest revision as of 16:42, 27 March 2024
 |
A membrane keyboard is a computer keyboard whose "keys" are not separate, moving parts, as with the majority of other keyboards, but rather are pressure pads that have only outlines and symbols printed on a flat, flexible surface. Very little, if any, tactile feedback is felt when using such a keyboard.
Membrane keyboards work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed. These models were used with some early 1980s home computers, enjoying wide adoption in consumer electronics devices. The keyboards are quite inexpensive to mass-produce, and are more resistant against dirt and liquids than most other keyboards. However, due to a low or non-existent tactile feedback, most people have difficulty typing with them, especially when larger numbers of characters are being typed. Chiclet keyboards were a slight improvement, at least allowing individual keys to be felt to some extent.
Aside from early hobbyist/kit/home computers and some video game consoles, membrane-based QWERTY keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for PDAs and other pocket computing devices. Smaller, specialised membrane keyboards, typically numeric-and-a-few-control-keys only, have been used in access control systems (for buildings and restricted areas), simple handheld calculators, domestic remote control keypads, microwave ovens, and other similar devices where the amount of typing is relatively small or infrequent, such as cell phones.
Modern PC keyboards are essentially a membrane keyboard mechanism covered with an array of dome switches which give positive tactile feedback.
Mechanism[edit]
The membrane (typically made out of Polyethylene terephthalate or PET) keyboard consists of three layers: two layers containing traces of conductive ink and the center layer is a "spacer" containing holes wherever a two conductive "key" pads count touch upon being pressed. The third layer keeps the other two layers separated in order to prevent short-circuit.
Under normal conditions, the switch (key) is open, because current cannot cross the non-conductive gap between the traces on the bottom layer. However, when the top layer is pressed down (with a finger), it makes contact with the bottom layer. The conductive traces on the underside of the top layer can then bridge the gap, allowing current to flow. The switch is now "closed", and the parent device registers a keypress.
Many applications benefit from the sealed nature of the membrane keypad. Feedback can easily be provided to the user via audible means (e.g. a beep) or visually (lights or via the display itself), or via both means together. For additional wear resistance, a simple, easily replaceable protective clear sheet can be placed in front of the membrane. Membrane keyboards are widely used in consumer electronics, industrial, commercial, scientific and military equipment.
