The present invention provides a protection device of a syringe needle. The protection device comprises a lower ring base, an upper ring base, and a sleeve. A raised rib ring is formed on an inside surface at a location close to a bottom face of the sleeve, and two elongate slit are extended from the bottom face along two side of the sleeve respectively in such a way that thickness of the intersections between the raised rib ring and the two elongate slits is less than the thickness of the raised rib ring itself, whereby when the sleeve is fit over the lower ring base and the upper ring base, an opening formed in the bottom face thereof is expanded by the applied external forces and the raised rib ring is simultaneously expanded. After being expanded, the bore of the raised rib ring changes from a shape that similar to an ellipse toward a circle therebypreventing being unable to fit to the circular lower ring base or the circular upper ring base.本發明係提供一種「注射筒針頭之防護裝置」,係由一下環座、一上環座及一套筒組成,該套筒靠近底面位置的內壁面上凸設有一圈凸肋環,並由底面往側邊面上各開設有一道長條裂縫槽,且該凸肋環與該兩長條裂縫槽相交接處的厚度小於凸肋環的自身厚度,當套筒進行套置於下環座及上環座時,其底面之開口被施力撐開後,凸肋環也會同步被撐開,而撐開後的凸肋環口徑形狀即會由類似橢圓形變形成圓形,因此不會發生與圓形之下環座或上環座無法相互套合之現象。1...注射筒1c...針頭10...下環座11...下凹環槽20...上環座21...上凹環槽22...漸縮錐面23...擋止凸緣30...套筒31...頂面32...穿透孔34...凸肋環35...側邊面36...長條裂縫槽37...張力孔P...推進桿
