Patent ID: 6821266
Filing Date: 2004-11-23
Classification: A61M

Abstract:
A safety syringe comprising:an elongated barrel having proximal and distal ends, a cylindrical interior wall, and openings at said proximal and distal ends; a needle assembly comprising a hollow needle and a needle base, the needle base being removably held in the distal end opening of the barrel with the needle projecting therefrom externally of the barrel in the direction of elongation of the barrel; a plunger extending through the proximal end opening of the barrel and having a resilient plunger tip sealingly engaged with the cylindrical interior wall of the barrel and slidable along said wall to draw fluid into the barrel through the needle and to expel fluid from the interior of the barrel through the needle; interlockable elements on the needle base and plunger for connecting the needle base to the plunger when the plunger tip is moved in the distal direction past a predetermined position, whereby, the needle base and plunger may be connected with each other, and the needle assembly can be drawn into the interior of the barrel by movement of the plunger in the proximal direction; a projection on the plunger adjacent the plunger tip; and a resilient insert secured to the barrel adjacent the proximal end thereof, the plunger extending through the resilient insert and the resilient insert permitting movement of the plunger in the direction of elongation of the barrel, the resilient insert having a cam surface engageable by said projection on the plunger to expand the insert when the plunger is withdrawn past a predetermined position in the proximal direction and permit resilient contraction of the insert when the plunger moves farther in the proximal direction, the plunger and insert having latching surfaces which move past each other when the insert is expanded by the engagement of the cam surface by said projection, and which are engageable with each other when the insert is resiliently contracted after the plunger makes said movement farther in the proximal direction, to prevent distal movement of the plunger after the needle assembly is withdrawn into the interior of the barrel.