Patent ID: 6050974
Filing Date: 2000-04-18
Classification: A61M

Abstract:
A hypodermic syringe comprising:a syringe housing having plunger and needle ends with a cavity therebetween for storing fluids to be administered to a patient, with said plunger end accommodating a syringe plunger and said needle end accommodating an automatically retractable needle assembly and a needle release assembly;a syringe plunger mated to the inside surface of the syringe housing with a pliable seal between the inside surface of the syringe housing and the outside surface of the plunger, said plunger having a housing with a closed end and an open end, wherein the closed end provides an end surface upon which pressure may be applied to the plunger to effect the movement of the plunger down the length of the syringe housing and into the lower portion thereof, with the open end being fitted with a thin membrane covering and sealing the end thereof, such that a vacuum is formed as the plunger is drawn toward the plunger end of the syringe housing, whereby a fluid may be drawn into the fluid holding chamber of the syringe and stored for use;a needle assembly housing tip for housing an automatically retractable needle assembly, wherein said housing tip is an elongated extension to the syringe housing and contains a spring under compression to maintain a force on the needle for effecting the ejection of the needle into the barrel of the plunger upon release of the needle assembly;means for coupling said needle assembly housing tip to the needle end of the syringe housing;an automatically retractable needle assembly, including a hypodermic needle having a pointed end extending through said coupling means, with the other end having a needle hub attached thereto, wherein the compressed spring exerts a force on the needle hub in a direction to force the needle into the barrel of the plunger, upon activation of the retracting mechanism;a rotatable release assembly, sitting atop the needle hub, holds the needle in a state of equilibrium until released, and includes a quasi-cylindrical rotatable member having an arcuate side and a substantially flat side, with said arcuate side seated within a conforming recess in the needle end of the syringe housing, said rotatable member having axle extensions extending longitudinally from the ends of the rotatable member and resting on shoulders within the syringe housing for supporting the rotatable member, said rotatable member further having a cylindrical passageway in the approximate center of the substantially flat side of the rotatable member for allowing the passage of the needle assembly therethrough during the automatic retraction of the needle, said passageway being fitted with an insert having a hole through the center thereof for allowing the free flow of injection fluids from the fluid holding chamber of the syringe housing to the hypodermic needle for use on a patient, said insert being loosely but frictionally fitted into the passageway, such that it can be easily dislodged by the needle hub upon activation of the automatically retractable needle, said rotatable member being rotated a few degrees from an imaginary cross-section of the syringe housing during the initial assembly, such that a solid portion of the arcuate side of the rotatable member remains in contact with the top of the needle hub to maintain the needle assembly in a state of equilibrium until such time as the needle assembly is released for storage, whereby, upon administering an injection to a patient, and as the plunger reaches the needle end of the syringe housing, the plunger makes contact with the edge of the rotatable member of the rotatable release assembly and gradually rotates the rotatable member until the opening in the center of the rotatable member becomes aligned with the needle hub of the needle assembly and simultaneously therewith, the compressed spring automatically forces the needle hub against the insert in the rotatable member, forcing the insert out of its resting place, extracting the needle from the patient, and thrusting the needle and its assembly through the opening in the rotatable member into the barrel of the plunger for storage.