The key switches of the keyboard of a computer system are generally comprised of a key cap having a plunger, conductive rubber disposed above a membrane circuit and compressed by the plunger to trigger the membrane circuit causing it to produce an electric signal to the computer. Some key switches use springs. Some other keyboards use rubber domes or a dome sheet, which do the function of springs. When the user depresses the key button the spring or domes collapse. The key switch depresses the key stem, which actuates the button on the membrane circuit. When the user releases the button the springs or rubber domes push the button up to the rest position. This article illustrates 10 inventions on different key switch mechanism. The inventions are selected from US patent database. The inventions try to simplify the mechanism, reduce manufacturing cost, increase accuracy and reliability, and increase strength and robustness of the keys.

Published in TRIZsite Journal, May 2005, also available in http://papers.ssrn.com/abstract=932273