An electrical switch contact member consists of a resilient electrically conductive domed diaphragm of a predetermined shape. The diaphragm includes a frusto-conical region linking a central region of the diaphragm with a peripheral region. The frusto-conical region includes an inwardly turned or bent...http://www.google.fr/patents/US4194105?utm_source=gb-gplus-shareBrevet US4194105 - Switches
