Editing Alps SKCL/SKCM series (section)

==Design==
Alps SKCL/SKCM series is widely referred to as "complicated Alps", due to the design of the switch. SKCL switches have a fairly high count of 10 [[parts per switch]], and the click or tactile leaf of an SKCM switch brings this to 11. The complexity comes from the [[switchplate]], the assembly that contains the electrical contacts.

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<gallery widths=250 heights=187>
File:Alps SKCM Orange -- side view.jpg      | A single Alps computer keyboard switch module
File:Alps SKCM Salmon -- infobox.jpg        | Alps switch fitted into a keyboard mounting plate
File:Alps SKCM blue complicated.jpg         | Blue Alps switches; while the exact Alps design was rarely copied, Alps-inspired switches are frequently mistaken for real Alps switches
File:Alps SKCM White -- opened switch.jpg   | In most Alps switches, the switchplate is at the rear of the switch with respect to the orientation of the logo and numbering
File:Alps SKC -- short switchplate, top.jpg | The [[switchplate]] that gives "complicated" Alps switches their complexity
File:Alps SKCM White -- disassembled.jpg    | Disassembled [[Alps SKCM White]] switch; SKCL/SKCM switches have a high number of constituent parts
File:Alps Diagram 1.png                     | Diagram of Alps SKCL/SKCM switchplate
File:Alps Diagram 2.png                     | Diagram of Alps SKCM with click leaf
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===Shell===
The original design was a linear switch, with a hole in the upper shell to take an integrated LED. The tactile or click leaf needs to occupy this slot, making tactility and illumination mutually exclusive; this design limitation would become a problem with the [[Matias Tactile Pro]] series, where customers mistook the necessarily linear LED key switches as manufacturing defects.

All standard linear switches have a recess for an LED. Surprisingly, most of these switches will not actually accept an LED, as there are no holes in the base for the LED legs. Separate part numbers existed for the LED versions, one per LED colour. The front securing tab for the shell also contains a clearance recess to provide room for the LED, which is also absent in the non-LED versions of linear switches. This clearance recess is subtle, but it is nonetheless visible in photographs of both yellow and green Alps switches.

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<gallery widths=250 heights=187>
Alps SKCLFQ and SKCLAR -- top.jpg                 | SKCLFQ (SKCLAR+red LED) and SKCLAR (no LED)
File:Alps SKCLFQ -- base detail.jpg               | SKCLFQ with adapted base design: note LED leg holes
File:Alps SKCLFQ and SKCLAR -- bases.jpg          | Base comparison; note the clearance recess for the LED in the securing tab on the left switch (SKCLFQ)
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In the 1980s, the whole switch shell was made of black plastic. At the very end the 80s, or the early 90s, the upper shell mouldings changed from black to dark grey. From this point onwards, switches would have two-tone grey-black shells, although they appear to have reverted to all-black again a while later.

Not long after this point, the Alps logo was added to the upper shell, allowing switches made from that point onwards to be positively identified as Alps Electric products instead of [[Alps clone]]s. The exact weight of typeface of the Alps logo varied between mould, and later it would change to boldface text.

The lower shell has four "wings" that retain the switch against the mounting plate. These wings may snap off or become weakened, possibly when removing switches from keyboards.

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<gallery widths=250 heights=187>
File:Alps SKCM Orange -- rear view.jpg            | [[Alps SKCM Orange]] switch with two-tone shell
File:Alps SKC -- broken wings.jpg                 | Broken wings found at the bottom of a bag of yellow Alps switches
File:Alps SKC -- broken wings on Cream Damped.jpg | [[Alps SKCM Ivory]] switch with missing wings
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===Slider===
The [[slider]] (Chinese and Japanese, "軸") is the moving connector between the keycap and [[return spring]]. The slider colour helps to identify the switch variant, in combination with other details such as the upper shell design.

Alps sliders are horizontally symmetrical (the right side mirrors the left side), but in most cases they are not rotationally symmetrical: the back is not a mirror of the front, and the slider is not considered to be reversible. In particular, there is a small notch cut into the base at the rear; this side always faces the switchplate. The notched side also has a rounded edge, presumably to ensure smooth actuation and minimize [[Chatter|contact bounce]]. The front side of the slider has a sharp edge which minimizes drag against the tactile leaf. Because of this, reversing the slider will make the switch feel heavier and less crisp. This design was maintained with [[Alps SKBL/SKBM series]] "simplified" Alps, but no Alps clone switches are known to have copied this characteristic, as they all have reversible sliders.

[[Alps SKCL Green]] is an exception here in that the slider is reversible, has a longer spring support stem, and equally-sized small notches on both sides. The change was not retained for [[Alps SKCL Yellow]].

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<gallery widths=250 heights=187>
File:Alps SKC -- non-reversible slider.jpg                                     | Front and rear view of Alps sliders
File:Alps SKCL -- reversible and non-reversible sliders.jpg                    | Green and yellow linear Alps sliders: green is an exception to this characteristic
File:Alps SKC -- slider orientation.jpg                                        | Slider orientation guide: notch side faces the switchplate
File:Alps SKCM -- difference between bottom edges on non-reversible slider.jpg | Side view of SKCM Ivory slider. Note the differences between the front (left) and rear bottom corners
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===Leaf springs===
Alps SKCL/SKCM series was quite likely to be the first switch series to use a [[click leaf|folded leaf spring]] to provide a tactile sensation and audible indication. Following on from [[Alps SKCC series]], the original SKCL switches were linear. It appears that the first attempt at tactile feedback was the [[Alps SKCM Brown]]; this was a skeleton switchplate designed to expand the tactility inherent in the actuator leaf design.

This was shortly followed by [[Alps SKCM Blue]], which introduced the idea of a folded leaf spring that is pulled away from the inside of the shell by the slider, and allowed to snap back into place to generate an audible sound. Blue Alps switches appeared around 1985, while the earliest [[SMK second generation]] switches have been found from 1986.

The click leaf concept was subsequently used in many switches, including SMK second generation switches and the [[Omron B3G-S series]] as well as most [[Alps clone]] switches, Alps derivatives, and Alps-SMK hybrid switches such as the [[KPT switch]].

The progression of the tactile leaf is not clear; it may have been a derivative of the click leaf, or it may be that both designs were introduced at the same time, as [[Alps SKCM Cream]], which so far has been found to have a standard folded tactile leaf. The folded tactile leaf is similar to the click leaf, but two additional protrusions prevent it from being pulled forward, so it does not generate a click. The consequence of this design is that the tactility is not as strong as that generated by a click leaf. Tactile leaves often have a hole stamped in the centre; the reason for this is not known. It appears to have been absent in SKCM Cream, then present for [[Alps SKCM Orange]] onwards, and removed again with [[Alps SKCM White Damped]].

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<gallery widths=250 heights=187>
File:Alps CM brown -- tactile assembly 1.jpg          | Original tactile leaf in SKCM Brown
File:Alps SKCM Amber -- click leaf.jpg                | Click leaf in an [[Alps SKCM Amber]] switch
File:Alps SKCM -- click and tactile leaves, front.jpg | Click leaf (left) compared to tactile leaf (right); the designs of both changed over time
File:Alps SKCM -- click and tactile leaves, rear.jpg  | Rear view of click and tactile leaves
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====Modification====
It is possible to modify a tactile leaf spring to produce a click. This is done by bending down the two upper tabs, which allows the leaf to move within the slot in the upper housing. This affects both the feel and the sound of the switch.

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File:Alps SKCM -- tactile leaf from cream damped switch.jpg                | A stock tactile leaf from an Alps SKCM Ivory switch.
File:Alps SKCM -- click-modified tactile leaf from cream damped switch.jpg | A click-modified tactile leaf from an Alps SKCM Ivory switch.
File:Alps SKCM -- tactile leaf cross section.gif                           | A cutaway view inside an Alps SKCM Ivory switch.
File:Alps SKCM -- click leaf cross section.gif                             | A cutaway view inside a click-modified Alps SKCM Ivory switch.
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===Switchplate===
The [[switchplate]] is a six-part sandwich assembly containing the electrical switch contacts. It contains two terminals, with a flexible metal foil membrane placed against the first that is held apart from the second by a plastic separator. This assembly is held inside a plastic plate, above which a sprung actuator leaf is fitted. The slider bends the actuator leaf back against the plastic plate, where it presses a flap against the foil membrane, which is pressed against the rear terminal.

The plastic block initially extended down to the base of the shell; this is a known as a "long" switchplate. Later switches had this plastic block reduced in height, leaving a gap between it and the bottom of the shell; this is termed a "short" switchplate. There has been speculation that reducing the length of the switchplate degrades the smoothness of the switch, but this seems unlikely. Short switchplates are supported by two small posts adjacent to the holes for the legs.

The colour of the switchplate has also changed twice. Early switches used the black switchplates from [[Alps SKCC series]] switches. The colour was soon changed to grey, with no other apparent change. Around 1987, the colour was changed again, to translucent white, which would be the final colour. The height was changed from long to short soon afterwards, around 1988.

In most switches, the switchplate is at the rear of the switch with respect to the orientation of the numbering and branding. [[Alps SKCM White]] was an exception, with certain production runs having the branding orientated "upside down", seemingly randomly between the different moulds in the tooling. Alps clone switches frequently placed the contacts at the front of the switch instead, and simplified Alps switches appear to have reversed the orientation initially.

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<gallery widths=250 heights=187>
File:Black Alps CM lower shell and switchplate.jpg | Opened black Alps switch showing the shorter switchplate
File:Switchplate -- Alps, short and long.jpg       | Short and long white switchplates
File:Alps SKC -- short switchplate, rear.jpg       | Rear view of short switchplate rear view
File:Alps SKC -- long switchplate parts, top.jpg   | Fully disassembled long white switchplate
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===Latching action===
{{main|Alps SKCL Lock}}

As with so many other vintage switch families, the SKCL series includes a latching action switch. This replaced the LED or leaf area with a follower arm. This switch was produced in two separate slider colours (cream and grey) with no known distinction between them. Alps SKCL Lock was widely used in Apple keyboards for the [[caps lock]] key, as Apple used latching caps lock keys in all their keyboards for years; other Alps switch keyboard manufacturers were more likely to use integrated LED switches instead.

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File:Alps lock slider in open position.jpg | Alps latching action design
File:Alps lock upper components.jpg        | Latch components
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===Slits===
On switches made up to 1993, the slider aperture contained a pair of prongs, one per side, possibly designed to dampen the impact of the return stroke. The resulting appearance of a switch shell with these prongs is described as "having slits", one above and one below each prong. These prongs, and thereby the slits, disappeared around 1993. MouseFan in particular considers the switch quality to have degraded around the time that the slits disappeared.<ref name="MouseFan" />

Based on MouseFan's terminology, switches with slits can be referred to as "pine" (「松」, ''matsu'') and switches without slits as "bamboo" (「竹」, ''take'') based on the Japanese three-tier grading system, with pine as the highest grade.<ref name="Digi_Joho" />

[[File:Alps SKCL-SKCM -- slits.svg|centre]]

The length of the tabs enclosed by the slits also changed with time; the tabs, and thereby the slits, had reduced in length after a couple of years. The longer tabs were potentially more prone to damage when pulling keycaps, as the tabs bear the strong keycap removal force by holding the slider down.

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<gallery widths=250 heights=187>
File:Alps SKCL Green -- variants table.jpg  | Typical SKCL Green, with longer tabs
File:Alps SKCL Yellow -- variants table.jpg | SKCL Yellow, with shorter tabs
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===Logo===
Early Alps SKCL/SKCM switches only bore the Alps logo on the bottom, where it could not be seen without removing the switch from the keyboard. Around 1988, Alps added their new-style logo the top of each switch, just after [[Alps SKCM White]] was introduced. At least two variants of this logo can be found, as Alps broadened the strokes of the letters.

The lack of visible branding on older Alps switches is one of the aspects of confusion between genuine Alps parts and [[Alps clone|clone]] switches, as most clone switches are completely unbranded.