Patent ID: 7198617

Claim:
A syringe for expelling fluid from a fluid chamber, said syringe comprising: an elongated hollow needle defining an axis and having a proximal end, and a distal end formed with a needle tip; an adapter for holding the proximal end of the hollow needle with the hollow needle extending in a distal direction from said adapter, said adapter being formed with an axially aligned slit; a guard formed with a slot and disposed on said needle for reciprocal axial movement thereon; a spring positioned between said guard and said adapter for biasing said guard along said axis in a distal direction from said adapter; an inverted plunger, said plunger being hollow and cylindrical shaped and having a closed proximal end and an open distal end; and a tang extending distally from said inverted plunger and inwardly through the slit of said adapter toward the needle axis for engagement with the slot of said guard, said plunger being axially moveable relative to said adapter in a proximal direction to create the fluid chamber, and moveable in a distal direction to expel fluid from said fluid chamber as said proximal end of said plunger moves in a distal direction against fluid in said chamber, and wherein during movement in the distal direction said plunger moves from a first (proximal) plunger position wherein said tang of said plunger holds said guard at a retracted location to expose said needle tip and into a second (distal) plunger position wherein said tang of said plunger releases said guard to cover and protect said needle tip.