Syringe needle guard

Claim 1

A device for preventing accidental needle sticks which comprises a syringe cartridge comprising a cartridge barrel with an internal and external surface, the cartridge barrel having a constricted distal end region, a piston movably disposed within the barrel, a hub having external threads and an axial bore mounted to the constricted distal end region of the barrel, and a hollow needle, the proximal end of the hollow needle projecting through the axial bore of the hub and the distal end having a pointed tip; a protective sheath having an inner diameter greater than the external diameter of the syringe cartridge, the protective sheath having an internal and external surface; the protective sheath having at least one longitudinal channel on the inside surface of the protective sheath extending from a first position to a second position, the first position being distal to the second position; the protective sheath having at least two pockets disposed in the longitudinal channel, with the first pocket located at the first position and the second pocket located at the second position; and a collar having an external surface mounted to the external threads of the hub, the collar having at least one ear on the external surface of the collar, the ear being disposed in the longitudinal channel, such that the protective sheath is slideably movable substantially coaxially along the external surface of the cartridge barrel from a first position in which the first pocket and ear are releasably engaged so that the tip of the needle extends distally past both ends of the protective sheath, to a second position in which the ear and second pocket are engaged so that the distal end of the sheath extends past the tip of the needle.

Claim 2

A device for preventing accidental needle sticks which comprises a syringe cartridge comprising a cartridge barrel with an internal and external surface, the cartridge barrel having a constricted distal end region, a piston movably disposed within the barrel, a hub having external threads and an axial bore mounted to the constricted distal end region of the barrel, and a hollow needle, the proximal end of the hollow needle projecting through the axial bore of the hub and the distal end having a pointed tip; a protective sheath having an inner diameter greater than the external diameter of the syringe cartridge, the protective sheath having an internal and external surface; the protective sheath having at least one longitudinal channel on the inside surface of the protective sheath extending from a first position to a second position, the first position being distal to the second position; the protective sheath having at least two pockets disposed in the longitudinal channel, with the first pocket located at the first position and the second pocket located at the second position; and a collar having an external surface mounted to the external threads of the hub, the collar having at least one ear on the external surface of the collar, the ear being disposed in the longitudinal channel, such that the protective sheath is slideably movable substantially coaxially along the external surface of the cartridge barrel from a first position in which the first pocket and ear are releasably engaged so that the tip of the needle extends distally past both ends of the protective sheath, to a second position in which the ear and second pocket are engaged so that the distal end of the sheath extends past the tip of the needle.