A key switch includes a base, a circuit board, a retaining board, a rubber spring, a support linkage and a key cap. A first engaging mechanism and a second engaging mechanism are formed on the base. The circuit board is positioned above the base and comprises a switch electrode. The rubber spring is...http://www.google.es/patents/US6040541?utm_source=gb-gplus-sharePatente US6040541 - Key switch
