Alps SKFF series

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Alps SKFF series
Manufacturer Alps Electric
Inventor Katsuyuki Matsuo
Switch type Clicky
Sense method Metal leaf
Keycap mount Generic cruciform
Patents US4186290 (1978)
US4249055 (1979)

Alps SKFF series, or Alps vertical plate spring, is a switch that shares characteristics of both Alps plate spring and Alps SKCC series. It is designed from the outset to support double action.


The Canon AP400 typewriter in which it was discovered bears the Alps keyboard codes 12KF006C and KFFBA010. The first code places the switch in the SKF family, normally used by simple contact arrangement PCB-mount switches. The latter code gives either SKFF or SKFB; considering that this code is comparatively short, it would appear to be one of the few codes without an extraneous "F" after the "K", giving SKFF.


Alps vertical plate spring switches differ from plate spring by having the plate spring assembly mounted vertically down the side of the switch. This change results in the switch being significantly more complicated than the original plate spring switch. The repositioning of the plate spring assembly allows for two separate plate spring assemblies to be fitted side by side, with a staged actuation to provide a double action response to the host.

The switch is clicky, and the click sound created by inversion of the plate spring is specifically mentioned in both US patents.

The ziggurat design of the slider is very similar to that of the Alps SKCC series switch.

The switch exists in single action and double action variants, and supports a spring-mounted LED just as with SKCC series.


  • Canon AP400 typewriter[1]


  1. Deskthority — Canon AP400