Protective needle assembly for hypodermic syringe

Claim 1

A needle-protecting assembly adapted for use with a conventional hypodermic syringe comprised of a barrel having a discharge extremity provided with needle-accepting means, said needle-protecting assembly comprising: a) a hub having a circular cylindrical sidewall disposed upon a central axis, a forward extremity having forwardly directed coupling means for engaging a mounting collar of a conventional cannula having a pointed extremity, a rear extremity having a recess configured to engage said needle accepting means, a control tab radially emergent from said sidewall, and a passageway extending between said coupling means and recess along said axis, and b) a transparent cylindrical sheath elongated between forward and rearward rims and configured to slide upon said sidewall and envelope said hub, said sheath having: 1) a longitudinal slot extending in parallel relationship to said axis between a first extremity and a second extremity forwardly spaced from said first extremity, 2) a circumferentially disposed arcuate slot communicating with said first extremity, and 3) a locking aperture circumferentially separated from said arcuate slot, c) said sheath engaging said control tab in a manner whereby reciprocal axial motion of the sheath is permitted when said tab is in said longitudinal slot, and an irreversibly locked condition is produced when the tab is in said locking aperture, said locked condition characterized in disposing the forward rim of the sheath forwardly of the pointed extremity of said cannula.