A plurality of keytops are held by means of a single leaf spring to prevent erroneous insertion of the keytops into opening portions formed in a frame and to prevent the keytops from being removed from the opening portions. For prevention of unstable movement of the keytops, the leaf spring holding a...http://www.google.es/patents/US4638151?utm_source=gb-gplus-sharePatente US4638151 - Keyboard of an electronic apparatus
