Retractable hypodermic needle assembly.

摘要

A syringe has a plunger (102) slidable in a cylindrical barrel (100) with a distal end nozzle, and a needle (106) mounted on a holder (108) slidably mounted in a plunger coaxial cavity (134) having a proximal part exposed through a helical slot (140). In normal use a distal part of the holder is engaged in the nozzle by a taper lock. To switch to retraction mode the lock is disengaged by plunger rotation w.r.t. the barrel. The holder is held against rotation w.r.t. the barrel but has a lateral arm (144) in the slot so that continued plunger rotation causes the arm to ascend through the slot and the holder to retract into the plunger cavity.