Low radial profile needle safety device

A needle safety device for an injection device having a generally cylindrical barrel with a distal end from which a cannula extends, the needle safety device comprising:

• an outer tube within which the barrel is slideably receivable, the outer tube having a distal end, a proximal end spaced from the distal end of the outer tube and a longitudinal axis;
• a collar positioned within the outer tube, moveable relative thereto and attachable to the distal end of the barrel;
• a force member positioned within the outer tube biasing the outer tube in a distal direction;
• a track formed in an inner surface of the outer tube;
• and
• a pin extending radially outwardly from the collar slidingly engaging the track,
• wherein the track comprises:
• a first track segment extending from a staging position to a pre-injection position,
• wherein the proximal end of the outer tube is in a position relative to the distal end of the barrel allowing the barrel to be inspected when the collar is attached to the distal end of the barrel and the pin is releaseably retained in the staging position by a first catch in the outer tube, and
• wherein the cannula extends a first length beyond the distal end of the outer tube when the collar is attached to the distal end of the barrel and the pin is releaseably retained in the pre-injection position by a second catch in the outer tube;
• a second track segment contiguous with the first track segment and extending from the pre-injection position to a full-insertion position,
• wherein the cannula extends a second length greater than the first length from the distal end of the outer tube when the collar is attached to the distal end of the barrel and the pin is in the full-insertion position;
• and
• a third track segment contiguous with the second track segment and extending from the full-insertion position to a locked position in which the pin is immovably retainable, a portion of the third track segment spaced from and parallel to a portion of the first track segment,
• wherein the cannula is entirely within the outer tube when the collar is attached to the distal end of the barrel and the pin is immovably retained in the locked position by a third catch in the outer tube.