Alps integrated dome
|This article requires additional photographic illustration — photos needed of some variants, and a family photo showing several variants side by side|
|Switch type||Tactile, linear|
|Sense method||Conductive dome|
|Keycap mount||Custom cruciform, Alps mount|
|Switch mount||Plate mount, PCB mount|
Alps integrated dome is a provisional name for a wide variety of discrete switches from Alps Electric which contain conductive rubber domes as part of the contact mechanism.
Alps keyboard codes suggest that these switches will have part numbers beginning "SKE". No part numbers have yet been discovered, but the switch modules in Alps semi-integrated dome switches appear to a variant of Alps SKEY series. One series name (SKEW) has been decoded to date.
Alps integrated dome switches appear from the outside as standard mechanical switches. However, they each contain a single rubber dome inside the switch. Two flat, horizontal metal contacts are placed side by side at the bottom of the switch; a carbon coating on the bottom of the dome conducts current between the contacts. The base of the switch appears to be moulded around the terminals/contacts, which cannot be removed.
The cross mount variants have the Alps logo embossed on the base. The Alps mount variants have the Alps logo embossed on the top; the base has not yet been examined.
Patent US5345051 filed in 1992 depicts an Alps SKE* switch. It appears to be a more compact arrangement than that found in the keyboard switch versions.
Alps integrated dome appears to be not a series, but a collection of similar series, across which there is a surprising variety of shapes and sizes.
White cross mount
Plate-mounted. The slider has a cross 4.5 mm across, with arms 1.2 mm wide. The side arms have a small bump on them that increases the effective width to 5 mm, and keycaps have a cross 5 mm wide and 4.5 mm long accordingly. Travel is 3 mm. Reported to be older than the black-slider version. Unlike other variants, the shell of the white slider variant is held closed by melted plastic lugs; these have to be drilled out in order to open the switch, after which point it will not remain reassembled. The Futaba clicky switch is also sealed in this manner.
Black cross mount
Plate-mounted. There is a helical spring above the dome; this variety is spring over dome. The shell design is completely different, with inverted retention tabs attached to the upper half instead of the bottom. This variant is described as "extremely linear and buttery smooth". Most rubber domes are shaped in a way that will produce a tactile bump when pressed. The rubber dome in this switch, however, is shaped in a way that it falls without a tactile bump, and simply collapses in a linear manner. This is what gives the switch its linear key-feel.
Alps mount (round slider)
PCB mounted. The Alps mount variant has the four legs at the base of the slider the same as the black cross mount version, but no helical spring. The upper shell has the inverted retention tabs, but no support for plate mounting, and a tiny Alps logo is present on the top; no Alps logo is found on the bottom. The blue slider is cylindrical all the way to the top, with a slot for standard Alps keycaps. The four legs appear to be the same spacing as the other variants, but this is not confirmed.
The four legs of the switch form the corners of a rectangle 13 mm by 5 mm.
The example depicted below is highly tactile and with a faint but distinct metallic sound. This cannot be taken as a certain characteristic, because the feel of rubber domes varies depending on condition of the domes.
Alps mount (central peg)
This variant appears to be identical to the blue slider version, with the exception of having a central peg in the slider slot as with Alps SKFL. Keyboards with these switches often use SKFL for one or more keys, such as where an LED is needed, which may account for the matching keycap mount.
Alps mount (square slider)
Similar to the round-slider variant, but with a square slider. These should not be confused with Alps semi-integrated dome, which have a similar slider but are not discrete switches. These are confirmed to be plate mount, and are identified as SKEW series by a keyboard identifier in a Canon typewriter keyboard.
Alps mount (square slider blue)
Similar to the square slider variant, but this variant is clearly plate mounted. The slider is sky blue. The source keyboard is not known. These appear to be outwardly identical to the white version above, except for the slider colour; these are therefore likely to also be SKEW series.
These do not have a separate lid. The entire shell is a single part, into which the slider is snapped. Removal of the slider without destroying the switch appears to be quite difficult. The source keyboard is not known.
- Some Apple Numeric Keypad IIe (black cross mount)
- Canon S-14 (SKEW white) (caps lock uses Alps SKCL Green)
- Canon S-66 MX (SKEW white) (three keys use Alps SKCL Green)
- Canon V20 (Alps mount, central peg) (space uses SKFL)
- DK'Tronics Spectrum Keyboard "Mk2" (the one with the full sized space bar) (black cross mount)
- Radio Shack TRS-80 Model III keyboard — Alps P/N 12KE010C (black cross mount)
- Some Radio Shack TRS-80 Model 4 keyboards (white cross mount)
- Ricoh R915-12 numeric keypad (Alps mount, square slider)
- Sharp PC-7000 portable computer keyboard (Alps mount, central peg) (LED keys use Alps low-profile oval slider switches)
- Tandy Model 102 (Alps mount, round slider)
- Toshiba Home Computer HX-10 (Alps mount, central peg); the HX-10D uses Alps SKFL switches
- Tulip LT 286 portable computer keyboard (Alps mount, round slider)
- Zenith Supersport SX 386 portable keyboard (Alps mount, round slider)
- Zenith ZA-180-89 numeric keypad (Alps mount, round slider)
- Maxi Switch integrated dome — appears to be a copy or clone
- Real World Interfaces — Replacing or repairing TR-808 switches and pots
- Reddit — [keyboard science] I managed to fit an MX switch into an Alps Integrated Dome plate
- ちゃたりたいね — ZENITH ZA-180-89 ALPS導電ゴム枕
- Nightfall Blog — Toshiba HX-10 64k (MSX) Keyboard PAD Fix.
- Deskthority — KBP V60 Build with SKCM Amber and Canon HiPros
- Deskthority — Gambled on a Canon typewriter (S-66 mx)
- Eski Bilgisayarlarım — Canon V-20
- Kevman 3D — Tech: Fixing the Dk'Tronics keyboard for my ZX Spectrum
- RobeesWorld.com — Repairing a dK'Tronics Keyboard and Scoping Out a ZX Spectrum 48k - Part One
- Google+ — Alps 12KE010C
- Knut Roll-Lund's web pages — Keyboard keyswitch cleaning
- MouseFan — RICOH テンキー R915-12
- Deskthority — Tulip LT 286
- Deskthority — Toshiba HX-10
- Deskthority — Calculator Canon MP 1210-D
- Google+ — Victor 12PD