Syringe Assembly and a Needle Unit for Attachment to a Syringe Unit to Form a Syringe Assembly

摘要

A retractable syringe is proposed having a cutting head mounted on a plunger of the syringe. When the plunger is advanced to expel fluid from the syringe, the cutting crown cuts a retention mechanism which holds a needle unit of the syringe, allowing a drive mechanism to drive the needle unit into the syringe. The cutting crown is shaped to reduce the force which has to be applied to cut the retention mechanism. Furthermore, a disposable needle assembly for attachment to a syringe unit is proposed. The disposable needle assembly has a needle and connector element for connecting the needle to the syringe unit. The connector element encircles the needle and has a thread on its outer surface for mating with the syringe unit.

主权项

1. A retractable syringe comprising:
a barrel; a needle unit comprising a needle, an interior of the needle being in fluid communication with a chamber within the barrel; a retention mechanism for retaining the needle unit at one end of the barrel; a hollow plunger movable within the barrel towards the needle unit; a drive mechanism for driving the needle unit into the plunger; and a cutting crown at the end of the plunger facing the needle unit, the cutting crown being arranged for cutting the retention mechanism as the plunger is advanced, so that the drive mechanism retracts the needle unit into the barrel; wherein a piston is disposed over the cutting crown, and the piston has a weakened portion which is arranged to be cut by the cutting crown before the cutting crown cuts the retention mechanism; and wherein the weakened portion comprises a plurality of notches.