No-prick hypodermic syringe

Abstract

An assembly for preventing accidental pricking by a hypodermic syringe includes a cap mounted on a needle hub for sliding between an extended position enclosing the needle and a retracted position exposing the needle. The cap slides on resilient bands extending arcuately from flaps projecting radially from the needle hub and structure is provided to retain the cap in both its extended position and its retracted position. The cap is tapered toward an end distal to a body of the syringe so that the resilient bands snugly frictionally engage the distal end of the cap to maintain the cap in the retracted position. In one embodiment of the invention, the flaps include portions extending radially beyond the resilient band, and the cap defines channels for receiving the flaps. The channels widen abruptly, at their ends adjacent to the syringe, to define slots into which the radially extending portions of the flaps can be twisted to lock the cap in its extended position. In another embodiment, elongate axial ribs defined on the interior surface of the cap are received in gaps provided between the flaps and adjacent free ends of the arcuate resilient bands. In addition, annular beads are provided on the interior surface of the cap to retain the cap in its extended position and to prevent the separation of the cap from the needle hub.

Dependencies are inferred from the claim text.