US Patent 11173252 Medicament delivery device

An injection device with a feedback mechanism includes a housing for a medicament container having a stopper, a plunger rod for acting on the stopper, a button interactively connected to the plunger rod, an activation member having a flexible locking device releasably connected to the plunger rod, a drive force device, a locking member slidable between positions in which the locking member either completely or partially surrounds the flexible locking device, and a guide rod. Audible and tactile information that an injection has started is provided by the plunger rod's hitting the stopper.