SMK spring over dome
|This article requires photographic illustration|
|Sense method||Conductive dome|
|Keycap mount||SMK two-prong ,|
|Switch mount||Plate mount|
SMK spring over dome is a name given to a keyswitch produced by SMK. The construction is described as "slider-over-spring-over-conductive rubber dome-over-PCB". It appears to be similar in concept to Alps integrated dome, except the contacts are on the PCB, rather than being contained within the switch module. A miniaturised version exists for use with small keys.
The PCB contains a pair of conductive traces for each key. Over this, switch modules are mounted on a plate. The modules contain a rubber dome with a conductive pad on the underside which bridges the traces when pressed. A spring sits over the dome, which in turn has a square slider on top.
Like other spring-over-dome switches, such as Fujitsu Peerless, the switch is linear until a distinct tactile/actuation event near the bottom, with only a slight click noise. Unlike the Peerless, however, it is very smooth and wider keys are fully stabilised. The normally muted click is louder in a disassembled keyboard.
The keycap mount consists of a pair of holes: north and south on the slider, for two prongs on the inside of the keycap.
There is also a miniaturised switch for use with smaller-sized keys. This appears to be similar in design to the full-sized version, but uses a different mount, with a cruciform shape.
Another switch which appears to be related to this and may be an additional variant has also been observed. This features a grey-coloured slider with a different pattern. The keycap mount is the same as the normal full-size version.
- Various Canon typewriters, including the S-51, Typestar 5 and Typestar 6 (Keys with lock lights have a round window in the top left of the cap.)
- DataDesk PC 8700 JR/XT
- Sony KI-9700P keyboard contains a potential variant
- Deskthority - Canon S-51 typewriter (SMK "peerless"?)
- YouTube - Hjalfi opens a Canon TypeStar 4 thermal typewriter
- Deskthority - IDENTIFY THE KEYSWITCH thread (page 3)
- Imgur - What switch is this? Canon Typestar 5
- Reddit - So I just found this machine and I'm not sure what switch is it. Is it just a rubber dome?
- Geekhack — DataDesk International PC 8700 (for IBM PCjr). Postged 2016-03-29. Retrieved 2019-05-05