US Patent 7104969 Safety syringe

Safety syringe that includes a cylindrical chamber having a front end that includes a discharge end, a plunger slidably coupled to the cylindrical chamber, and a needle holder structured to receive a needle having at least a portion of which that protrudes from the discharge end. A cylinder unit is slidably arranged within the front end, and a plunger seal, coupled to the plunger, is arranged for movement relative to the plunger after medicament discharge. The plunger is arranged to slidably move the cylinder unit toward the discharge end and to slidably dislodge the plunger seal. The cylinder unit is structured to provide a protective shield around the portion of the needle protruding from the discharge end.