| 摘要 |
An injection device for use with a syringe 30 having a bore extending from an end surface 34, a needle 36 communicating with the bore through the end surface and a dispensing piston 38 movable in said bore towards said end surface so as to expel the content of the syringe through the needle, the injection device including a housing 60 having an opening at one end through which the needle may extend, a resilient member 74 for biassing the syringe and needle inwardly of the housing, a drive element movable towards said one end so as to move the needle of the syringe out of the opening against the bias of the resilient member and to move the dispensing piston of the syringe towards the end surface, a delatch mechanism 72 operable to release the syringe such that the needle moves inwardly of the housing, a drive coupling 40 for extending from said drive element to the dispensing piston of the syringe so as to transfer movement of said drive element to the dispensing piston, wherein the drive coupling gradually reduces in length such that, after the drive element has moved the dispensing piston to the end surface, the drive element continues to move to said predetermined position at which said delatch mechanism releases the syringe. The drive coupling may be a fluid 52 with a bleed valve 56 such that it reduces in length during its travel. The drive coupling may also be a direct engagement which is released when the needle extends out of the housing. |
