Retractable syringe with a cutting crown

摘要

A retractable syringe comprises 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 comprises 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. When the needle assembly is mated with the syringe, a central bore of substantially constant bore extends from the tip of the needle into the interior chamber of the syringe.

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; the profile of the cutting crown including at least two cutting teeth which cut a first portion of the retention mechanism before other portions of the cutting crown cut other portions of the retention mechanism, the at least two cutting teeth having interspaced between each consecutive cutting tooth an arcuate bridge spanning from tooth to tooth.