HYPODERMIC SYRINGE WITH RETRACTABLE NEEDLE MOUNT

摘要

A hypodermic syringe (10) comprising a barrel (14) for containing medicament or other liquid, movable piston means (16) including a shaft (40) provided with a chamber (42) and frangible chamber sealing means (20), needle mounting means (22) disposable within barrel (14), spring means (18) for imparting movement to needle mounting means (22), and restraining means (28) in barrel (14) comprising an annular structure (36) located towards first end (30) of barrel (14) extending inwardly thereof and containing a plurality of radially-extending weakened portion (38), wherein needle mounting means (22) when in a first position extends partway from first end (30) and is restrained from movement by engagement with restraining means (28), the restraining means (28) being operable to release needle mounting means (22) when piston (16) approaches first end (30) and then to engage and restrain piston (16) from reverse movement, the needle mounting means (22) on release having been propelled through frangible diaphragm (66) to a second position wherein it is received and retained within chamber (42) in a jamming relationship.