| abstract |
The invention relates to an autoinjector (1) with a housing, a product container, a torsion spring (15), a drive element (13), and a propulsion element (14). In order to discharge liquid out of the product container, the torsion spring (15) rotates the drive element (13), and the rotating drive element (13) produces a propulsive movement of the propulsion element (14) and of a piston in the product container. The autoinjector also comprises a rotation sensor (22) for an alternating continuous detection of at least two rotational positions per revolution of the drive element (13) during the discharge process and a processor unit for determining the axial position of the piston in the product container from the detected rotational positions. |