An apparatus for use with a syringe for providing a safety syringe, the apparatus comprising: a sheath (100 300 500) deployable for at least partially covering a needle (126) of the syringe and a sheath actuator (102 302 502) for deploying 5 the sheath by interaction with a sheath deployment mechanism (104 304 504) wherein the sheath is configured to be stationary in relation to the needle until a syringe plunger (116 316 516) reaches a sheath release point on its inward stroke, and wherein the sheath actuator is configured for deployment of the sheath on movement of the sheath actuator relative to the syringe plunger after the sheath release point.一種可與一注射器一起使用以提供一安全注射器的裝置,該裝置包含:一套鞘可展開用以至少部份地掩蔽該注射器之一針;及一套鞘致動器可藉與一套鞘展開機構互動以展開該套鞘;其中該套鞘係構製成會相對於該針固定不動,直到一注射注塞在其向內衝程達到一套鞘釋放點,且其中該套鞘致動器係構製成可在該套鞘致動器於該套鞘釋放點之後相對於該注射柱塞移動時來展開該套鞘。100‧‧‧套鞘102‧‧‧套鞘致動器104‧‧‧套鞘展開機構108‧‧‧裝座110‧‧‧小齒輪112‧‧‧圓筒114‧‧‧固定物116‧‧‧注射柱塞117a、117b‧‧‧扣持凸耳118‧‧‧第一齒條120‧‧‧第二齒條122‧‧‧齒126‧‧‧針
