US Patent 7455661 Safety shield system for prefilled syringe

A medical device is provided which includes a shield system and a syringe which is coupled to the shield system. The shield system includes a syringe holder and a shield which is slidably coupled to the holder. A spring resiliently urges the shield from a retracted position to an extended position. Stop members are provided on the holder and shield for maintaining the shield in the retracted position. The syringe is slidably coupled to the holder, and extends within the shield. Axial movement of the syringe with respect to the holder causes disengagement of the stop members, allowing the spring to move the shield to the extended position. Detents are provided on the holder for maintaining the shield in the extended position.