U.S. Utility Patent 4,118,611 (US4118611A)

Provided by the ASK Keyboard Patents database

Patent diagrams of IBM's buckling spring torsional snap actuator at rest (left) and pressed (right)
A patent chart illustrating the force curve for IBM's buckling spring torsional snap actuator
Applied 30th August 1977
Published 3rd October 1978
Expired 30th August 1997
More informaion
NameBuckling spring torsional snap actuator
InventorsRichard H. Harris
AssigneesIBM Information Products
DescriptionAn invention of a buckling spring actuator for use with a capacitance-sensing PCB to make a capacitive keyswitch now typically known as "IBM capacitive buckling springs". It builds upon the work of its predecessor patent from 1971 (US3699296A). It was used for all Model F family keyboards.

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