FOLDED- PLUNGER AUTO-RETRACTABLE DISPOSABLE SYRINGE

Patent Pending The present invention relates to a safety syringe having an auto retractable needle for use in the medical or dental profession or in personal drug administration so that the physicians, surgeons or other needle operators may be protected from the needle-stick injury during its use. The invention, in particular, relates to an assembly of the safety syringe which is simple and easy in handling, in which the hypodermic needle retracts itself automatically by virtue of self generated vacuum and encapsulate within the barrel as soon as the last drop is injected in the body of patient. The syringe thereafter becomes finally locked to become non-reusable. The handling of syringe does not require any special training to the operators. It is simple in manufacture. The present subject matter relates to a folded- plunger auto-retractable disposable syringe which includes a needle carrier assembly and a folded plunger assembly for respectively inserting in an outermost barrel. The folded plunger assembly is provided with at least one oppositely positioned circumferential C-groove on the outer surface at its proximal end P constituting a ridge. The folded plunger assembly also includes at least one outwardly protruded finger lock to get engaged with an outer plunger barrel and a piston seal holder structures at the proximal end P for holding a piston seal. The outer plunger barrel includes at least two pair of oppositely positioned finger locks distal end of the barrel where two diameters of barrel bisect each other perpendicularly. The outer plunger barrel is also provided with a second piston seal holder at proximal end P for holding second piston seal. The present subject matter also discusses about the needle carrier assembly for housing in the outermost barrel before inserting the folded plunger assembly. The needle carrier assembly includes a hypodermic needle provided with a needle seat at its distal end to hold a needle at the proximal end of the hypodermic needle. The needle carrier assembly is further provided with a spring surrounding the needle to push the hypodermic needle through the spring and an axial passage present in a needle carrier hub. The needle carrier hub is advantageously provided with three different diameters to firmly hold the needle seat. The present invention further explains that the outermost barrel is designed to receive the folded plunger assembly after getting in the needle carrier assembly wherein the outermost barrel is provided with a finger rest, two uniform obtuse-angled L-shaped inner circumferential conical grooves and a conical jacket opening at the proximal end of the outermost barrel.