Brother buckling spring
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In the late 1980s, IBM Japan moved from using Alps plate spring switches in their keyboards to a buckling spring design. The buckling spring mechanism used was designed and manufactured for IBM Japan by Brother Industries, and thus is referred to by Japanese collectors as the Brother switch. The first keyboard to use this switch was the 5576-003. The only other known keyboard to use it was the more common 5576-A01.
The Brother switch operates like a membrane buckling spring, but differs primarily in the construction of the keyboards that use it. In an IBM Model M, the barrels in which the buckling springs are housed are all formed on the one sheet of plastic. In a 5576-003 or -A01, each buckling spring assembly has its own individual barrel module, which can be removed from the keyboard without dismantling.
It has been erroneously claimed that the Brother switches are individual switching units. In reality, because they all share the same common membrane, this is not the case. IBM Model F keyboards are constructed in a very similar way, except that the individual barrels are covered and held in place by a metal plate, meaning they cannot be removed without completely dismantling the keyboard. While it might seem like a clever idea to have separate buckling spring assemblies to allow broken ones to be fixed, the reality is that the membrane common to all the removable switches is a much more likely point of failure. It is more likely that the individual nature of the buckling spring assemblies was more suitable to Brother for manufacturing than the Model M design.
The Brother switch uses a shorter spring than the Model M resulting in a stiffer and shorter travel. They also have quite a distinctive noise: a metallic 'twang' as opposed to the ping of Model M and Model F switches. Nonetheless, they have been described as very pleasant to type on, and superior to the Model M by some.
- Qwerters Clinic — IBM BucklingSpring Keyboard (IBM 5576-003, 5576-A01, 101model M, etc...) Last updated 2004-01-20. Retrieved 2015-07-23.