HYPODERMIC SYRINGE WITH NEEDLE RETRACTION FEATURE

摘要

A hypodermic syringe (10) permits a needle (16) to be fully retracted into the cylindrical cavity of the syringe barrel (14) following injection of medicine into a patient. The needle (16) is held on the distal end of the barrel (14) by an attachment hub (43), which includes an internal abutment surface to prevent outward movement of the needle (16). Inward movement of the needle (16) is prevented by an expandable restriction (51) of a distal barrel (14) opening, extending between the cylindrical cavity and the distal end of the barrel (14). Needle (16) includes a flange (44) held between the internal abutment surface of hub (43) and the expandable restriction (51). The distal end of the plunger (12) is fitted with a needle extractor (42), which, when depressed, grips the proximal end of the hub (43) and expands the expandable restriction (51) so that the needle (16) and flange (44) are pulled into the cylindrical cavity of the barrel (14) as the plunger (12) is pulled outward.