Drive mechanism for an injection device.

摘要

An injection device having a drive mechanism 42 to expel selectively a dose of medicament from a medicament cartridge 40 through a needle unit 22 is disclosed. The injection device further comprises an electronic control unit to control the drive mechanism 42, and a dispense button 18 to generate a dispense button signal to the electronic control unit indicative of the dose to be expelled in which an arm button 16 causes a first arm button signal to be sent to the electronic control unit to permit the dose to be expelled.