Safety syringe apparatus

Abstract

An apparatus for use with a syringe to provide a safety syringe, the apparatus comprising: a sheath ( 100; 300; 500; 700; 900; 1100; 1300 ) deployable for at least partially covering a needle of the syringe; a sheath actuator ( 102; 302; 502; 702; 902; 1102; 1302 ) for deploying the sheath; and a ratioed mechanism ( 104; 304; 504; 704; 904; 1104; 1304 ) linking the sheath and the sheath actuator and configured such that a magnitude of movement of the sheath is greater than a magnitude of movement of the sheath actuator during deployment of the sheath.

1 . An apparatus for use with a syringe to provide a safety syringe, the apparatus comprising:
 a sheath deployable for at least partially covering a needle of the syringe;   a sheath actuator for deploying the sheath;   a ratioed mechanism linking the sheath and the sheath actuator and configured such that a magnitude of movement of the sheath is greater than a magnitude of movement of the sheath actuator during deployment of the sheath, and   wherein the ratioed mechanism defines a helical guide configured to be rotatable by the sheath actuator and to engage with a corresponding feature of the sheath for linear deployment thereof.   
     
     
         2 . An apparatus according to  claim 1 , wherein the helical guide is located on a mount, rotatable by the sheath actuator with respect to the sheath. 
     
     
         3 . An apparatus according to  claim 1 , comprising a further helical guide configured to engage with a corresponding feature on the sheath actuator for rotation of the helical guide. 
     
     
         4 . An apparatus according to  claim 3 , wherein the plunger comprises a safety plunger coupled to a syringe plunger, the safety plunger being configured decouple from the syringe plunger at a point on a stroke of the syringe plunger,
 and wherein the further helical guide is located on the safety plunger and/or the syringe plunger for relative rotation therebetween after decoupling.   
     
     
         5 . An apparatus according to  claim 3 , wherein the further helical guide is located on the mount. 
     
     
         6 . An apparatus according to  claim 3 , wherein the helical guide and/or further helical guide comprise channels and the corresponding features on the sheath actuator and the sheath comprise lugs and/or a corresponding helical protrusion. 
     
     
         7 . An apparatus according to  claim 3 , wherein the angle of the helical guide is greater than the angle of the further helical guide. 
     
     
         8 . An apparatus according to  claim 3 , wherein the helical guides are in opposed directions. 
     
     
         9 . A safety syringe comprising a syringe and an apparatus according to  claim 1 . 
     
     
         10 . A kit of parts comprising:
 a sheath;   a sheath actuator for deploying the sheath; and   a ratioed mechanism,   wherein, when fitted to a syringe, the sheath is deployable for at least partially covering a needle of the syringe and the ratioed mechanism links the sheath and the sheath actuator and is configured such that a magnitude of movement of the sheath is greater than a magnitude of movement of the sheath actuator during deployment of the sheath, wherein the ratioed mechanism comprises a helical guide configured to be rotatable by the sheath actuator and to engage with a corresponding feature of the sheath for deployment thereof.