Patent ID: 8052655

Claim:
An injection device for injecting a dose of drug, the injection device comprising: a dose setting mechanism being operable to set a desired dose, operation of said dose setting mechanism causing energy to be stored in a spring member, an injection mechanism comprising a piston rod adapted to cooperate with a piston positioned in a cartridge containing a drug to be delivered in order to cause a set dose to be delivered from the cartridge via the injection device, said injection mechanism being driven by releasing energy previously stored in said spring member during dose setting, means for electronically detecting the amount of a set dose and/or means for electronically detecting the amount of an injected dose, and electronic display means for displaying a set dose and/or an injected dose to a user wherein the amount of a set dose and/or the amount of an injected dose is/are detected by means of a relative displacement between two members, and that the means for electronically detecting the amount of a set dose and/or the means for electronically detecting the amount of an injected dose is/are adapted to detect said relative movements of a movable member being mechanically biased along said relative displacement by a spring force.