Injection device

An injection device, comprising a syringe with a hollow needle and a stopper for sealing the syringe and displacing a medicament (M) stored in the syringe, the injection device further comprising a drive means, a plunger arranged for pushing against the stopper and an arrangement for transferring a translation of the drive means to the plunger, wherein the arrangement comprises an elongate release latch member pivoted at one end which is connected to either the drive means or the plunger, the release latch member having another end for engaging the respective other one of the drive means or the plunger, wherein the release latch member is arranged to have its non-pivoted other end disengaged by rotation due to contact between at least one ramp and another component when the stopper has at least nearly displaced all of a predefined dose of the medicament (M), wherein a length of the release latch member is specified so as to provide a clearance between the plunger and the drive means when the release latch member is engaged in order to allow at least the plunger, the stopper and the hollow needle to be retracted at least far enough to hide the needle inside the syringe or inside a housing after disengaging the release latch member,

• wherein the release latch member is arranged to be disengaged depending on a distance travelled until at least all of the predefined dose has been delivered,
• wherein the release latch member is arranged to be disengaged depending on a time elapsed from a beginning of the translation,
• wherein a damper unit is arranged in series with the drive means and the release latch member, the damper unit comprising a viscous damper, and
• wherein the viscous damper comprises a piston fixed to a drive collar by a connecting rod, the drive collar being arranged at a proximal end of the drive means, the piston having a greater diameter than the connecting rod, wherein a hollow cylinder with an internal diameter slightly greater than the diameter of the piston is arranged around the piston thus allowing the piston and cylinder to reciprocate, wherein a proximal end face of the cylinder is fully closed and wherein a distal end face of the cylinder is arranged to seal the cylinder against the connecting rod, wherein at least one transfer port is provided through the piston in a manner to allow a fluid to flow between the distal side of the piston and the proximal side.