Auto-injection device

A pharmaceutical injection assembly comprising:

• a casing having a band carried thereby for being worn by a user and for storing the injection assembly;
• an injection device initially carried within the casing, the injection device being removable from the casing by displacement of a cap on the casing;
• wherein the injection device comprises:
• a housing;
• a first activator having a protrusion extending outwardly from a first end of the housing, the first activator being biased to extend the protrusion outwardly relative to the housing, the protrusion defining a contact surface for being pressed against an injection site of the user;
• a syringe within the housing and having a needle extending forward towards an aperture defined in the protrusion, wherein, in operation, the syringe is translated towards the first end of the housing when the first activator is translated towards the syringe;
• a first spring providing a spring force that biases the syringe towards the first end of the housing;
• and a detent extending rearward within the housing, the detent having a forward end affixed to an interior side of the housing and a rearward end opposite the forward end, wherein the rearward end of the detent, when in a first position thereof, supports the syringe against the spring force of the first spring;
• wherein movement of the protrusion inwardly relative to the housing translates the first activator towards the syringe and imparts movement of the rearward end of the detent laterally away from the syringe thereby releasing the syringe to be moved towards the first end of the housing under the spring force of the first spring, wherein the syringe further comprises:
• a plunger;
• a forward end from which the needle extends;
• a chamber for storing an injection substance between the plunger and forward end of the syringe;
• and a second activator, wherein, when the syringe is released, forward movement of the syringe towards the first end of the housing causes activation of the second activator and movement of the plunger towards the forward end of the syringe to dispense the injection substance through the needle for injection into the user, wherein the second activator begins to move forward along with the plunger when the syringe is released, wherein the second activator comprises:
• at least one ball engaged with the plunger before the syringe is released;
• and a pin attached to the housing and maintaining the ball in engagement with the plunger before the syringe is released, wherein, when the syringe is released, the pin releases the at least one ball from engagement with the plunger thereby activating the second activator and causing movement of the plunger towards the forward end of the syringe to dispense the injection substance through the needle.