A key pad has resin key tops on a key sheet. The resin key tops have in their side surfaces clearance portions of a configuration in conformity with an outer configuration of interference members at least an upper portions of which are situated in displacement regions at bottom surface edges of the resin...http://www.google.co.uk/patents/US7014377?utm_source=gb-gplus-sharePatent US7014377 - Key pad, resin key top injection mold, and resin key top manufacturing method
