NEEDLE RETRACTION MECHANISM WITH CONSISTENT RETRACTION SPEED

摘要

A needle retraction mechanism (10) includes a hollow handle (20) with a longitudinal axis defining a cavity (21) wherein the cavity has an inner diameter that decreases from its proximal portion to its distal portion. Included in the mechanism is an elongate needle (30) with an open bore therethrough with a sharp distal point (31) and a proximal end (32). The needle (30) has a first position where it is disposed in the cavity (21) so that the sharp distal point (31) of the needle (30) is proximal of the distal portion of the handle (20) and a second position where it is disposed within the cavity (21) so that the sharp distal point (31) of the needle (30) projects axially beyond the distal end (23) of the handle (20). A needle hub (40) is connected to the needle. The needle hub (40) includes a flexible stopper (45) at its proximal end that creates an air tight seal with the inner wall of the handle (20). This allows a vacuum to be created between the proximal end (22) of the handle (20) and the flexible stopper (45) when the needle hub (40) is moved from the first position to the second position. The tapered configuration of the cavity (21) results in consistent retraction speeds for the mechanism.