Three position needle retraction

A needle insertion and retraction mechanism for an injector having a housing with a base defining an opening, the needle insertion and retraction mechanism comprising:

• an injection needle mounted to a needle retainer, the needle retainer being linearly slidable along a first track between a retracted position, in which a tip of the injection needle is within the housing, and an extended position, in which the tip of the injection needle projects outward from the housing through the opening;
• a shield defining a needle aperture and having an interference element extending therefrom, the shield being movable relative to the housing between a deployed position, in which the needle aperture is misaligned with the injection needle and a withdrawn position, in which the needle aperture is aligned with the injection needle;
• a retraction spring engaged with the needle retainer at one end and engaged with the shield at an opposing end;
• a driver engageable with the needle retainer, the driver being linearly slidable along, and rotatable about, a second track, the driver being slidable by a main spring, the retraction spring and the main spring providing biasing forces in opposing directions;
• and
• an activation button depressible to rotate the driver about the second track into engagement with needle mount;
• wherein:
• in a pre-activation state of the insertion and retraction mechanism before the injector is placed on a skin surface of a patient, the biasing force of the retraction spring orients the shield in the deployed position, in which the interference element blocks downward movement of the activation button, locking the needle retainer and the injection needle in the retracted state, and the retraction spring is in an expanded configuration and the main spring is in a compressed configuration;
• in a primed state of the insertion and retraction mechanism, the injector is placed on the skin surface of the patient and the shield is moved to the withdrawn position thereof, in which the retraction spring is partially compressed and the interference element is moved out of the way of the activation button;
• in an activation state of the insertion and retraction mechanism, the activation button is depressed, engaging the driver with the needle mount and freeing the main spring to push the driver and the engaged needle retainer and the injection needle into the extended position, thereby further compressing the retraction spring;
• and
• in an intermediate state of the insertion and retraction mechanism after the injector is removed from the skin surface of the patient, the driver is disengaged from the needle mount, and the retraction spring partially expands and returns the shield to the deployed state, in which the shield restricts the needle mount from returning to the retracted position and covers the tip of the injection needle, and wherein subsequent contact with the shield toward the withdrawn position releases the needle mount, whereby the retraction spring further expands and retracts the needle mount and injection needle.

A needle insertion and retraction mechanism for an injector having a housing with a base defining an opening, the needle insertion and retraction mechanism comprising:

• an injection needle mounted to a needle holder, the needle holder being rotatable about a central axis thereof to unlock downward movement thereof and linearly slidable between a retracted position, in which a tip of the injection needle is within the housing, and an extended position, in which the tip of the injection needle projects outward from the housing through the opening;
• a needle extension spring biased to push downwards on the needle holder;
• a retraction slider engageable with the needle holder, the retraction slider being rotatable about a central axis thereof into a vertically unlocked state and being linearly slidable in the vertically unlocked state;
• a needle retraction spring biased to push upward on the retraction slider;
• an activation button;
• a skin sensor defining a needle aperture, the skin sensor having an arm extending therefrom and a safety latch extending therefrom, the skin sensor being movable relative to the housing between a deployed position, in which the needle aperture is misaligned with the injection needle and a withdrawn position, in which the needle aperture is aligned with the injection needle, the skin sensor being biased into the deployed position;
• wherein:
• in a pre-activated locked state of the insertion and retraction mechanism before the injector is placed on a skin surface of a patient, the skin sensor being in the deployed position, in which the safety latch blocks downward movement of the activation button, locking the needle holder and the injection needle in the retracted state;
• in a primed unlocked state of the insertion and retraction mechanism, the injector is placed on the skin surface of the patient and the skin sensor is moved to the withdrawn position thereof, in which the safety latch is moved out of the way of the activation button;
• in an activation state of the insertion and retraction mechanism, the activation button is depressed, rotating the needle holder to unlock downward movement thereof, thereby freeing the needle extension spring to push the needle holder and the injection needle into the extended position;
• and
• in an armed state of the insertion and retraction mechanism after the injector is removed from the skin surface of the patient, the skin sensor returns to the deployed state, in which the skin sensor covers the tip of the injection needle, and wherein subsequent contact with the skin sensor toward the withdrawn position engages the arm with the retraction slider to rotate the retraction slider into the vertically unlocked state, whereby the retraction spring expands and retracts the retraction slider, the needle mount and injection needle.