Patent ID: 7794430

Claim:
A drive mechanism for an injection device in which a piston is successively moved along a first axis in a first longitudinal direction in relation to a first end of a medicament cartridge containing a medicament selectively to drive a bung closing the first end of the medicament cartridge into the medicament cartridge to expel medicament through a delivery member located at a second end of the medicament cartridge, the first axis being a central longitudinal axis of the medicament cartridge, wherein a displacement mechanism comprises a dose setting spindle disposed along a second axis around which the dose setting spindle is rotatable, the second axis being parallel to the first axis and the second axis being separate from the first axis, a transmission means connected between the dose setting spindle and the piston, and a displacement means to displace the dose setting spindle with respect to the medicament cartridge, a movement of the displacement means in the first longitudinal direction causing movement of the dose setting spindle and the piston in the first longitudinal direction.