Patent ID: 6613016
Filing Date: 2003-09-02
Classification: A61M

Abstract:
A safety hypodermic syringe comprising:a body unit, said body unit comprising a barrel, a hollow cylindrical connector inserted into said barrel and stopped inside a front end of said barrel, and a needle hub fastened to said connector and holding a needle cannula outside said barrel; and a plunger unit, said plunger unit comprising a stepped plunger fitting said barrel, said stepped plunger having a front tip, a hollow stopper mounted on said stepped plunger around said front tip, and a flexible safety cap capped on said hollow stopper, said flexible safety cap having a locating groove of smoothly arched cross section extended around the periphery thereof; wherein said hollow cylindrical connector has a plurality of inside annular flanges adapted to secure said needle hub to said connector; said stepped plunger has an annular groove extended around the periphery: thereof near said front tip; said hollow stopper has an inside annular flange forced into engagement with the annular groove of said stepped plunger; said front tip is forced through said flexible safety cap into engagement with the inside annular flanges of said hollow cylindrical connector when said plunger continuously forced forward after a forward stroke of said flexible safety cap and said hollow stopper with said plunger to expel a liquid medicine out of said barrel through said needle cannula, for enabling said needle hub and said needle cannula to be moved with said connector and said flexible safety cap and said hollow stopper backwards to the inside of said barrel upon a back stroke of said plunger; said front tip is breakable when said plunger biased by an external force after said connector has been moved with said plunger backwards to a rear end of said barrel.