US Patent 9375532 Auto-injector

Described is an injection device for administering a dose of a medicament comprising a case having a proximal end and a distal end, a carrier adapted to accommodate a syringe, and a trigger button. In a first state, the trigger button is coupled to the case and/or the carrier and abuts the distal end of the case. In an intermediate state, the case moves proximally relative to the carrier and the trigger button, and the trigger button engages the carrier. In a second state, the trigger button and the carrier move proximally relative to the case, and the trigger button disengages the carrier and engages the case.