Patent ID: 7918821

Claim:
A syringe assembly, comprising: an elongated barrel with a nozzle at a distal end thereof, said barrel defining a longitudinally elongated cavity therein; a resilient O-ring mounted within said nozzle; a plunger defining a longitudinally elongated channel and having a resilient cap on the distal end of the plunger, wherein said plunger is movably arranged at least partially in said barrel to transition between a fully retracted position and a fully advanced position; a needle; a longitudinally elongated needle holder attached at a distal end thereof to said needle and extending from said needle through said resilient cap and into said elongated channel, wherein said needle holder is movably arranged at least partially in said channel of said plunger to move between a first position, in which said needle projects at least partially from said distal end of said nozzle, and a second position, in which said needle is fully enclosed within said barrel; a spring retainer operatively attached to said barrel and spaced proximally from said resilient cap; a spring operatively supported by said spring retainer, wherein said spring mates with and biases said needle holder toward said second position; a first latch latching said needle holder to said spring retainer to thereby maintain said spring in a compressed state, wherein said first latch is repositionable in response to contact with said plunger when said plunger is moved to said fully advanced position independently of said spring so that said plunger repositions said first latch without compressing said spring, whereby said needle holder is released from said spring retainer allowing said compressed spring to expand and thereby move said needle holder to said second position; and a second latch latching said plunger to said barrel in response to movement of said plunger to said fully advanced position thereby preventing movement of said plunger relative to said barrel after said plunger has moved to said fully advanced position.