Patent ID: 8092424

Claim:
A safety syringe comprising: a needle carrier, said needle carrier comprising a body having a central cavity, the central cavity of said needle carrier having a substantially cylindrical cross section, an open end and an end wall, the end wall of said needle carrier having an opening adapted to receive a hollow needle; a hollow needle attached to the end wall of said needle carrier, said hollow needle having a sharp distal end and a central lumen opening into the central cavity of said needle carrier a syringe barrel comprising a generally cylindrical body disposed within the central cavity of said needle carrier, said syringe barrel having a proximal end, a distal end and an interior cavity, the interior cavity of said syringe barrel having a substantially cylindrical cross section, an open proximal end and a distal end having a distal wall, the distal wall of said syringe barrel having an opening adapted to receive a cannula; a cannula attached to the distal end of said syringe barrel and disposed coaxially within the central lumen of said hollow needle, said cannula having an interior lumen opening into the interior cavity of said syringe barrel, said cannula having a blunt distal end, said syringe barrel being moveable between a retracted position in which the blunt end of said cannula is within the central lumen of said hollow needle to an extended position in which the blunt end of said cannula extends beyond the sharp distal end of said needle; and a helical track and track engaging member assembly coupling said syringe barrel and said needle carrier for advancing said syringe barrel, whereby rotating said syringe barrel relative to said needle carrier advances said syringe barrel and said cannula from the retracted position to the extended position.