Torsion Spring Injection Device Having An End-Of-Dose Mechanism

The present invention relates to a torsion spring based automatic injection device for apportioning set doses of a liquid drug and which injection device is provided with an End-of-Dose feedback mechanism providing a user with an audible signal once the set dose has been injected. During injection, the scale drum rotates back to its "zero" position under influence of the torsion spring. This rotation is halted shortly before reaching the "zero" position by stopping means. The scale drum is thereafter only allowed to continue rotation and thus reach the "zero" position once the torque applied to the scale drum by the torsion spring surpasses a threshold value.