Abstract: The present invention provides a drug delivery device (1) of the type in which a piston rod (10, 110) extends along a reference axis and is forced to rotate in an expelling direction about the reference axis during a dose expelling event to cause an expelling of drug from a drug reservoir (30, 130), and a resilient ratchet element (12) is operatively coupled with the piston rod (10, 110) and undergoes a deflecting motion comprising elastic deformation and recovery in response to an expelling of a predetermined dose increment, which deflecting motion occasions a velocity fluctuation of the piston rod (10, 110), comprising: a rotator module (50, 150) operatively coupled with the piston rod (10, 110) and configured to rotate about the reference axis against a rotation resisting force in response to a rotation of the piston rod (10, 110) in the expelling direction, the rotator module (50, 150) comprising a sensor system (70, 71; 170, 183; 270, 183) for monitoring a torque transferred by the piston rod (10, 110) d

Abstract: The present invention provides a piston washer (1, 51) for a drug delivery device, the piston washer (1, 51) comprising a central portion (2, 72) arranged about a centre axis, a peripheral portion (3, 73), and an axially pliable structure (8, 78) connecting the central portion (2, 72) and the peripheral portion (3, 73). The axially pliable structure (8, 78) is preconfigured to undergo permanent deformation in response to a difference between a first resultant force acting on the peripheral portion (3, 73) and a second resultant force acting on the central portion (2, 72) exceeding a threshold level.

Abstract: The present invention provides a drug injection device (1) comprising a housing (2) extending along a longitudinal axis and comprising an exterior housing surface, an activation element (20, 50) configured to undergo movement relative to the housing (2) corresponding to an action performed on or by the drug injection device (1), a transducer (90, 91, 92) arranged on a transducer bearing portion (8.1, 9.1, 9.2) of the exterior housing surface, a processor (82) electrically connected with the transducer (90, 91, 92), and an energy source (95). The transducer bearing portion (8.1, 9.1, 9.2) is capable of deflection relative to other portions of the exterior housing surface, the activation element (20, 50) is arranged to deflect the transducer bearing portion (8.1, 9.1, 9.2) in accordance with said movement relative to the housing (2), the transducer (90, 91, 92) is adapted to register a deflection of the transducer bearing portion (8.1, 9.1, 9.

Abstract: The present invention provides a piston washer (1, 51) for a drug delivery device, the piston washer (1, 51) comprising a central portion (2, 72) arranged about a centre axis, a peripheral portion (3, 73), and an axially pliable structure (8, 78) connecting the central portion (2, 72) and the peripheral portion (3, 73). The axially pliable structure (8, 78) is preconfigured to undergo permanent deformation in response to a difference between a first resultant force acting on the peripheral portion (3, 73) and a second resultant force acting on the central portion (2, 72) exceeding a threshold level.