Buckling Springs

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The buckling spring design originates from IBM in the 1980's, as a cheaper and equally or more reliable replacement for various technologies used in preceding keyboards. It was invented by Richard Hunter Harris and IBM was granted U.S. Patent 4,118,611 for the buckling spring on October 3, 1978. Buckling spring keyboards were manufactured for everything from the PS/2 personal computer to Point of Sale terminals and the 3151 InfoWindow terminals.

All buckling spring keyboards are 'click tactile' as a function of the spring reaching the 'breaking' point and buckling. This causes the actuating hammer to contact the membrane, and the spring to collide with the barrel. The typical actuation force of a buckling spring keyboard is between 70 and 80cN, depending on the wear and tear.

Being an old design, most buckling spring keyboards have controllers which draw >300mV of current. Some modern i8042 implementations have trouble providing this much current, resulting in the keyboard not functioning. Many PS/2 to USB adapters also have a limit of 250mV which can have a similar effect.


  • IBM (IBM, Lexmark, MaxiSwitch)
  • Unicomp

Current Buckling Spring Keyboards

Common Buckling Spring Keyboards

Uncommon or Rare Buckling Spring Keyboards

Controller Information