Patent ID: 8684969

Claim:
An injection device comprising -p 1 a torsion spring ( 12 ) operatively connected to a dose setting member ( 1 ), the dose setting member ( 1 ) being adapted to set a dose to be ejected from the injection device, and a rotatably mounted display member adapted to display the dose to be ejected from the injection device in accordance with a setting of the dose setting member ( 1 ), the rotatably mounted display member being rotatable over an angle corresponding to at least one revolution of the display member, wherein the rotatably mounted display comprises a dose indicator barrel; wherein the display member is adapted to be moved between two end positions, said two end positions defining an operation range of the display member, said operation range being associated with a substantially linear working range of the torsion spring; wherein the injection device further comprises: a housing ( 5 ), a piston rod ( 2 ) having a threaded outer surface with a drive track ( 7 ) arranged in a longitudinal direction of said outer surface, wherein the dose setting member ( 1 ) is rotatably mounted and defines a passage for the piston rod ( 2 ), the dose setting member ( 1 ) further having a guiding track ( 11 ) arranged on an inner surface thereof, a rotatable drive member ( 6 ) being adapted to at least partly engage with at least part of the drive track ( 7 ) of the piston rod ( 2 ) so as to drive the piston rod, wherein the dose indicator barrel ( 9 ) has a part engaging at least part of the guiding track ( 11 ) of the dose setting member ( 1 ), the dose setting member ( 1 ) and the dose indicator barrel ( 9 ) being movable in relation to each other, the dose indicator barrel ( 9 ) further having a threaded outer surface ( 8 ) cooperating with a threaded inner portion ( 10 ) of the housing ( 5 ) whereby the dose indicator barrel ( 9 ) undergoes a combined translational and rotational movement in relation to the housing ( 5 ) upon rotation of the dose setting member ( 1 ), and wherein the injection device has a threaded portion ( 3 ) cooperating with the threaded outer surface of the piston rod ( 2 ) so that rotation of the piston rod ( 2 ) relative to the housing ( 5 ) results in a longitudinal movement of the piston rod ( 2 ).