An injection device for injection of a medicament from a medicament cartridge 40 is disclosed. The injection device comprises a main housing 4, a piston 50 and an end stop switch 52 in which access to the main body 4 for replacement of the medicament cartridge 40 may only be obtained when the piston...http://www.google.com/patents/US20040078001?utm_source=gb-gplus-sharePatent US20040078001 - Injection device with replacement cartridge
