Safety medical syringe with retractable needle

摘要

A syringe for giving medical injections which has an internal mechanism for retracting the needle into the syringe after the injection has been given and locking the needle and plunger inside the barrel of the syringe to reduce the risk of accidental needle pricks. In one embodiment the needle is retracted by a tension spring into a compartment inside a hollow plunger and in the other embodiment the needle is propelled by a compressed spring into a compartment within the plunger. In both embodiments, the interior of the hollow plunger is hydraulically sealed off by a barrier from the fluid chamber of the syringe to prevent fluid from entering the interior of the hollow plunger.