Patent ID: 7645265

Claim:
An injection device comprising an outer housing inside which is located: a barrel for holding a volume of a medicament; a needle at one end of the barrel, the needle and barrel being such that at least part of the needle is axially moveable in and out of the outer housing but is biased to be normally wholly inside the housing; a plunger, axially moveable within the barrel; an inner housing at least partially intermediate the outer housing and at least one of the barrel and plunger; and an energy source in communication with the inner housing, wherein the inner housing is moveable by the energy source between three positions, namely: a first position in which a plurality of radially flexible tags formed as part of the inner housing are in communication with the barrel such that, in use, the plunger and the barrel are movable by the inner housing axially so as to move at least part of the needle out of the outer housing; a second position in which one or more of the radially flexible tags formed as part of the inner housing is in communication with the plunger but not the barrel such that, in use, the plunger is movable axially into the barrel so as to expel medicament through the needle; and a third position in which one or more of the radially flexible tags formed as part of the inner housing is in communication with neither the plunger nor the barrel such that, in use, the plunger and barrel are able to retract in order to retract the needle into the outer housing.