Abstract: An injection device (210) is described. A housing (212) receives a syringe and includes a return spring (226) for biasing the syringe from an extended position in which its needle (218) extends from the housing (212) to a retracted position in which the it does not. A drive spring (230) acts on a first drive element (232) and a second drive element (234) acts upon the syringe to advance it from its retracted position to its extended position and discharge its contents through the needle. The first drive element (232) is capable of movement relative to the second (234) once a nominal decoupling position has been reached. A release mechanism is activated when the first drive element (234) is further advanced to a nominal release position, to release the syringe (214) from the action of the drive spring (230), whereupon the return spring (226) restores the syringe (214) to its retracted position. A locking mechanism (337, 375) confines the returned syringe in its retracted position.

Abstract: An injection device 110 is described having a housing 112 that receives a syringe 114 having a needle 118, wherein the syringe is supported in a syringe carrier 150. The syringe 114 and syringe carrier 150 are biased by a return spring 126 from an extended position in which the needle 118 extends from the housing 112 through an exit aperture 128 to a retracted position in which it does not. A drive spring 130 acts via a drive to advance the syringe 114 from its retracted position to its extended position and discharge its contents through the needle 118 and a return spring 126, brought into play when the drive has reached a nominal return position, restores the syringe 114 to its retracted position. The injection device is less prone to failure than prior art devices and is safer should failure occur.