Needle bearing medical device with three-position shield

Claim 1

In a medical device comprising an elongated structure having proximal and distal end sections and an internal liquid passageway, a hollow needle having a point and an opposite end axially mounted at said proximal end section of the elongated structure in communication with said liquid passageway, and a tubular protective shield having first and second end portions, said shield mounted around a portion of said elongated structure and longitudinally movable from a needle-covering position, wherein the first end portion of said should extends beyond said needle point to a needle-exposing position, the improvement comprising: a plurality of angular, inwardly-depending raked teeth circumferentially formed along an inner surface of the second end portion of said tubular protective shield; a plurality of angular, outwardly-extending raked teeth around the distal end section of said elongated structure, the angle of said outwardly-extending teeth being substantially complementary to the angle of the inwardly-depending teeth on said protective shield; a distal retaining ring extending annularly around the distal end section of said elongated structure for cooperating with said inwardly-depending teeth on said protective shield to releasably hold said shield in a needle-exposing position; an intermediate retaining ring extending annularly around said elongated structure, between said outwardly-extending teeth and said distal retaining ring, for cooperating with said inwardly-depending teeth on said protective shield to releasably hold said shield in a needle-covering position; and at least one cut-out in the surface of of said protective shield for facilitating the mounting of said shield around said elongated structure.