Patent ID: 6488657
Filing Date: 2002-12-03
Classification: A61M

Abstract:
A needle holder positioning structure for safety hypodermic syringe comprising:a barrel, said barrel comprising a fluid chamber, said fluid chamber having a front small inner diameter section, a rear big inner diameter section, a shoulder connected between said front small inner diameter section and said rear big inner diameter section, and an inside flange means disposed in said rear big inner diameter section adjacent to said shoulder; a needle holder mounted in said barrel, said needle holder comprising a tubular center base and a sleeve coaxially formed integral with the periphery of said tubular center base, said tubular center base having a retaining portion near a rear side thereof, said sleeve having a front engagement section press-fitted into the inside of the front small inner diameter section of the fluid chamber of said barrel and a springy rear expansion section, said rear expansion section having a front side edge corresponding to a back side of said shoulder of said barrel and a rear side edge stopped at a front side of the inside flange means of said barrel, said rear expansion section defining with the periphery of said tubular center base a backwardly extended annular coupling chamber; and a locating ring mounted inside said barrel and coupled to said needle holder, said locating ring having an outside wall disposed in contact with an inside wall of the rear big inner diameter section of said fluid chamber of said barrel for enabling said locating ring to be moved axially in said barrel, an inside wall disposed in contact with the periphery of said tubular center base of said needle holder for enabling said locating ring to be moved axially relative to said needle holder, the outside wall of said locating ring having a front section forming a neck adapted for engaging into said rear expansion section of said sleeve of said needle holder, said neck having an outer diameter not less than the inner diameter of said expansion section of said sleeve of said needle holder so as to expand said rear expansion section of said sleeve for enabling the rear side edge of the rear expansion section stopped at the front side of the inside flange means of said barrel, a first retaining portion integral with a front part of the inside wall of said locating ring and adapted for engaging the retaining portion of said tubular center base of said needle holder, and a second retaining portion formed integral with a rear part of the inside wall of said locating ring.