Automatic injector having door block until proper cartridge insertion

An automatic injector device for delivering a pharmaceutical substance from a cartridge having a protruding edge, said cartridge positioned in a housing of said device, said housing comprising:

• a cartridge bay having an opening sized to allow passage of said cartridge into said cartridge bay;
• a door to said cartridge bay opening, said door connected to said housing and having an unlatched position and a latched position, said door defining a trajectory between the unlatched position and the latched position;
• an interference element having a deflected and an inflected orientation, said deflected orientation mechanically interferes with said trajectory of said door;
• and
• a contact interface positioned along said cartridge bay and extending up to said protruding edge, said contact interface mechanically couples said deflected and inflected orientation with a sensed contact of said protruding edge, such that when said protruding edge is positioned at said contact interface, said contact interface shifts said interference element into said inflected orientation.