| abstract |
A pen shaped syringe with automatic needle insertion has an injection system integrally displaceable in a housing and comprising a basic part carrying a medicine reservoir with a hypodermic needle at its distal end, and a dosing mechanism with a carrier engaging a cogged piston rod, the carrier being coupled to a dose spindle in a rotatable but not displaceable way. The dose spindle is provided with a thread engaging a thread in a sequence part having protrusions engaging slots in the basic part to allow a limited axial movement of the parts in relation to each other, the extent of the movement being defined by the rotational position of the dose spindle. A spring is compressed between the basic part and the housing when the basic part is moved in the proximal direction by exerting a cocking force on the sequence part which part after having performed the set limited axial movement in relation to the basic part carries this basic part against the force of the spring. |