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Apple and Logitech Butterfly Switches

Logitech and Apple have both come out with alternatives to the scissor-like mechanism, and these are generically called “butterfly switches”.

They have the same function, to spread the force across any portion of the keytop, to the entire keytop, so the keytop moves down vertically, rather than topples over to the side.

Think of how the legs of a folding ironing table, table, or chair work: the scissor-like legs allow the table surface to move up and down, while remaining parallel to the floor. The scissors allow vertical movement without toppling.

Photgraphed by Frank C. Müller

In a regular keyboard, the vertical motion is regulated by a column of plastic that holds the keycap.  In a very flat, laptop keyboard, it’s not possible to have a column that’s tall enough to hold the key vertical.  So, instead, the plastic scissors keep the keycap level.

Logitech, in 2009, came out with their butterfly switch, and it had a longer travel than laptop keyboards, according to their blog.

Apple, in 2015, came out with their butterfly switch, to make their keyboard thinner: this thread at Deskthority has pictures of the mechanism.

One company uses a mechanism to get the keys to move more, and the other, to move less. So, why do they use this butterfly shape instead of the scissor?  Probably due to some patent issues.



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