Editing Contact module

A '''contact module''' or contact assembly is a unit within [[metal contact switch]]es which contains the switch contacts and usually the solder terminals. With [[Alps SKCL/SKCM series]] switches, they are inexplicably termed "'''switchplates'''", a term also seen used to refer to the [[mounting plate]] within a keyboard.

==Description==
The contact module is a plastic assembly that contains and supports the electrical contacts. Such a module can be inserted and removed from the switch. Without such a module, the bare contacts are supported purely by the switch shell. After removing a contact module, the contacts are still fully supported.

Switches that use contact modules include:

*[[Alps SKCC series]]
*[[Alps SKCL/SKCM series]]
*[[Alps SKCP series]]
*[[Mitsumi standard mechanical]]
*[[Omron B3G-S series]]
*[[Omron Alps-style switch]]

==Alps==
The Alps contact module design appears to have originated in [[Alps SKCC series]], and was adopted wholesale into the [[Alps SKCL/SKCM series]] switches with no discernable alteration. Alps keyboard switches with this type of contact module have model numbers beginning SKC, where "C" appears to denote this contact arrangement. [[Alps SKCP series]] uses largely the same design as SKCC, SKCL and SKCM, but the contact module is laid flat across the bottom of the switch and the shapes of the parts are adapted slightly to suit the switch.

The Alps design comprises a complex sandwich of metal and plastic layers, hence the term "complicated" when referring to Alps switches. [[Alps SKBL/SKBM series]] (simplified Alps) and [[Alps clone]]s replaced this whole assembly with bare contacts, using  and grooves in the upper shell for support. Simplified Alps switches are fairly easy to reassemble, but with many clones switches, forcing the thick contacts down the fine grooves in the upper shell is fiddly and taxing.

{{Switch recognition characteristic
| image name         = Alps internals--CM, complicated, grey switchplate.svg
| object name        = Alps SKCC/SKCL/SKCM switchplate
| object description = Long grey switchplate from an early [[Alps SKCL/SKCM series]] switch
}}

{{Switch recognition characteristic
| image name         = Alps clone internals--CP, both, APC older.svg
| object name        = Simplified clone switch
| object description = Simplified contact mechanism in an early [[Tai-Hao APC series]]; the stationary contact is still the full width of the switch
}}

===Long switchplates===
The original switchplate in Alps switches was the full internal height of the switch. These are termed "long switchplates". In early SKCC and SKCL/SKCM switches, the supporting block was coloured black. Subsequently this changed to pale grey, and finally colourless. Long switchplates can be fully disassembled and reassembled, although after the melted heads of posts that hold it together are snapped off, it will not hold itself together once removed from the switch, and it will need to be glued.

<gallery widths=250 heights=187>
File:Alps tee green slider plate and spring 1.jpg   | Black switchplate from an SKCC switch, together with the [[slider]] and [[return spring]]
File:Alps tee green slider plate and spring 2.jpg   | Rear view of the switchplate
File:Alps SKC -- long switchplate parts, top.jpg    | Full disassembly: top view of parts (rear to front)
File:Alps SKC -- long switchplate parts, bottom.jpg | Full disassembly: bottom view of parts (front to rear)
</gallery>

===Short switchplates===
Around 1988, the switchplate height was reduced, and the internal contact construction was altered. The large foil membrane was reduced to a smaller strip, and instead of being a loose fit, it was crimped into two holes in the front terminal. The switch shell gained two small posts on the inside to support the switchplate, which sits above the bottom of the switch. Short switchplates were used with all of SKCC, SKCL and SKCM series switches.

Full disassembly of a short switchplate is essentially impossible, as the foil contact membrane is crimped into one of the terminals and cannot be removed with tearing it.

<gallery widths=250 heights=187>
File:Switchplate -- Alps, short and long.jpg                      | Short and long switchplates
File:Alps SKC -- long and short switchplate blocks.jpg            | Long and short switchplate front mounting blocks
File:Alps SKC -- short switchplate, top.jpg                       | Front view
File:Alps SKC -- short switchplate, rear.jpg                      | Rear view
File:Alps SKC -- short switchplate with rear terminal removed.jpg | Rear contact/terminal removed to reveal the separator and foil membrane
File:Alps SKC -- switchplate foil membrane types.jpg              | Foil membrane comparison from short (left) and long (right) switchplates
File:Alps SKC -- foil membrane is fragile.jpg                     | Foil membrane is fragile; note the different foil colours
</gallery>

===Alps plate spring===
A very similar design was used in the [[Alps SKCP series]] "plate spring" switches, modified to lie flat across the bottom of the switch.<ref>Qwerters Clinic — [http://ex4.sakura.ne.jp/kb/tech_alps_5576001.htm ALPSメカニカルスイッチ IBM 5576-001, 5576-002]</ref>

==Omron==
===B3G-S series===
[[Omron B3G-S series]] contact modules have an actuator leaf almost identical to Alps Electric's design, but the internals are completely different, with simple metal leaf contacts. As with Alps switchplates, these contact modules are secured with heat staking and will not hold together once disassembled.

<gallery widths=250 heights=187>
File:Omron B3G-S series switchplate.jpg                           | Omron B3G-S series contact module
File:Omron - Switchplate.jpg                                      | Contact module opened up
File:Omron - Switchplate2.jpg                                     | Contact module opened up
</gallery>

==References==
<references />

[[Category:Keyboard terms]]