The syringe according to the invention comprises elastic means for blocking the intake stroke of the plunger which are initially located in an inactive position and are transferred into an active position during the first syringe intake and injection operation. When in said active position the elastic...http://www.google.ca/patents/US4850968?utm_source=gb-gplus-sharePatent US4850968 - Self-blocking hypodermic syringe for once-only use, comprising a needle protection cap
