Patent ID: 6669666
Filing Date: 2003-12-30
Classification: A61M

Abstract:
A safety syringe comprising:a syringe means having a syringe cylinder formed with a sleeve portion on a front portion of said syringe cylinder; a needle device detachably secured on said syringe cylinder and including: a hollow needle, a shank portion for externally connecting the hollow needle thereon and a locking head portion formed on a rear portion of said shank portion; and a plunger means slidably held in said syringe cylinder, having a plunger secured to a plunger rod and recessed with a biasing socket in said plunger for coupling said locking head portion of said needle device in said biasing socket when completing an injection, said plunger as coupled with said needle device operatively retracted into said syringe cylinder for tilting said needle without re-protruding said needle forwardly from said sleeve portion; the improvement which comprises: said sleeve portion having a plurality of sleeve ribs longitudinally formed on an inside wall in a sleeve hole formed through said sleeve portion; said shank portion having a plurality of shank ribs longitudinally formed on an outer surface of said shank portion for respectively engaging said sleeve ribs in said sleeve portion, and a shallow disk portion formed on a rear portion of said shank portion to be engaged with a shallow recess formed in a rear portion of said sleeve hole of said sleeve portion, whereby upon securing of said shank portion in said sleeve portion and upon rotation of said shank portion, said shank ribs on said shank portion will be engaged and locked by said sleeve ribs in said sleeve portion for preventing a rotation of said shank portion, thereby allowing a smooth connection of said hollow needle on said shank portion on said syringe cylinder; and said plunger means including at least a ratchet tooth formed on a rear portion of a circular disk which is formed on a front end portion of said plunger rod adjacent to said plunger, and said syringe cylinder having an annular extension annularly formed in a rear portion of said syringe cylinder; whereby upon a rearward pulling of said plunger rod, said ratchet tooth will be engaged and locked by said annular extension in said syringe cylinder for preventing a rearward releasing of said plunger means from said syringe cylinder once inserted into said syringe cylinder.