Patent ID: 6863659
Filing Date: 2005-03-08
Classification: A61M,Y10S

Abstract:
1. A single use hypodermic syringe with a retracting needle system comprising: a cylindrical body element for containing a fluid; a needle assembly comprising a needle holding member and a hollow needle, the needle holding member repositionable between an injecting position wherein the needle projects axially outward from the body element and a pre-use and post-use position wherein the needle is retracted and contained completely within the body element; a plunger rod reciprocally received into the body element forming a fluid chamber between the cylindrical body element, the plunger and the needle holding member, and whereby positive and negative pressure forces are generated by adjustment of the plunger within the body element whereby fluid is drawn into, and expelled from, the body element through the hollow needle; a retraction mechanism comprising: a spring between the needle holding member and the axial end of the cylindrical body element through which the needle member projects and which generates an axial pressure on the needle holding member; at least one retaining member engaging the needle holding member and retaining the needle holding member against the axial force of the spring; at least one activating member within the needle holding member responding to positive fluid pressure within the fluid chamber to release the retaining member from the needle holding member; whereby the needle is automatically deployed into the injecting position by depression of the plunger prior to drawing fluid into the fluid chamber and is automatically retracted within the body element at the completion of an injection stroke of the plunger and which retraction renders the syringe safe for handling and disposal.