Autoinjector

1. An autoinjector comprising:

a case adapted to hold a medicament container having a needle;

a needle shroud telescopically coupled to the case and movable between a first extended position relative to the case in which the needle is covered and a retracted position relative to the case in which the needle is exposed;

a shroud spring biasing the needle shroud in a distal direction relative to the case; and

a cap removably coupled to the case, wherein the cap includes at least one compliant case beam adapted to releasably engage at least one aperture in the case, wherein, when the cap is moved in the distal direction relative to the case, the at least one compliant case beam disengages the at least one aperture in the case and no longer radially abuts the case, wherein a force required to disengage the at least one compliant case beam from the respective aperture is greater than a force exerted by the shroud spring on the cap when the compliant case beam is engaged in the aperture, wherein, when the cap is removed, the needle shroud is released and translates in the distal direction relative to the case under the force of the shroud spring.

2. The autoinjector of claim 1 , wherein the autoinjector further comprises:

a plunger rotationally and slidably disposed in the case, the plunger being rotatable relative to the case between a first rotational position in which the plunger is engaged to the case and a second rotational position in which the plunger disengages the case,

wherein the needle shroud engages the plunger to prevent rotation of the plunger from the first rotational position to the second rotational position when the needle shroud is in the first extended position,

wherein the plunger includes a first plunger boss adapted to engage a shroud rib disposed on the needle shroud and a second plunger boss adapted to engage a case slot in the case,

wherein, when the plunger is in the first rotational position and the needle shroud is in the first extended position, the first plunger boss engages the shroud rib and the second plunger boss engages the case slot,

wherein the second plunger boss is prevented from disengaging the case slot, because the shroud rib prevents the plunger from rotating relative to the case, and

wherein, when the needle shroud is in the retracted position, the plunger rotates from the first rotational position to a second rotational position and disengages the case slot.

3. The autoinjector of claim 1 , wherein the autoinjector further comprises:

a plunger rotationally and slidably disposed in the case, the plunger being rotatable relative to the case between a first rotational position in which the plunger is engaged to the case and a second rotational position in which the plunger disengages the case,

wherein the needle shroud engages the plunger to rotate the plunger from the first rotational position to the second rotational position when the needle shroud translates from the first extended position to the retracted position, and

wherein the plunger includes a plunger boss adapted to engage a case slot in the case, and a plunger rib adapted to engage a shroud rib disposed on the needle shroud,

wherein when the plunger is in the first rotational position and the needle shroud is in the first extended position, the plunger boss engages the case slot, and

wherein, when the needle shroud translates from the first extended position to the retracted position, the needle shroud abuts the plunger rib to rotate the plunger relative to the case from the first rotational position to a second rotational position to disengage the plunger boss from the case slot.

4. The autoinjector of claim 2 , wherein, when the cap is removed, the needle shroud translates in the distal direction relative to the case until the shroud rib abuts the first plunger boss.

5. The autoinjector of claim 1 , wherein the compliant case beam is designed to resolve the force from the shroud spring and allow removal of the cap.

6. The autoinjector of claim 1 , wherein the force exerted by the shroud spring on the cap is in a range from 2 N to 10 N whereas a force required to remove the cap is greater.

7. The autoinjector of claim 1 , wherein the autoinjector comprises a first shroud lock mechanism which is arranged to prevent retraction of the needle shroud relative to the case when the cap is in place, thereby avoiding unintentional activation of the autoinjector,

wherein the first shroud lock mechanism comprises one or more compliant shroud beams on the cap and a respective number of apertures in the needle shroud adapted to receive each of the compliant shroud beams, wherein the one or more compliant shroud beams are different from the at least one compliant case beam,

wherein, when the cap is in place, the shroud spring is in an at least slightly loaded state, and

wherein the load of the shroud spring is statically resolved between the case and the shroud which are coupled through the compliant case beams and the compliant shroud beams on the cap.

8. The auto-injector according to claim 1 , wherein the cap comprises:

a distal face;

at least one compliant sheath removal beam extending in a proximal direction from the distal face and defining a space for receiving a protective needle sheath, the at least one compliant sheath removal beam including at least one ledge adapted to engage the protective needle sheath,

wherein the at least one compliant sheath removal beam is disposed approximately perpendicular to the distal face in a first position for engaging the protective needle sheath and is disposed at a non-approximately perpendicular angle to the distal face in a second position for receiving the protective needle sheath.

9. The auto-injector according to claim 8 , wherein the at least one compliant sheath removal beam is biased toward the first position.

10. The auto-injector according to claim 8 , wherein the ledge is adapted to engage proximally behind a proximal end of the protective needle sheath or into a recess within the protective needle sheath.

11. The auto-injector according to claim 8 , further comprising one or more openings in a distal face of the cap or one or more lateral apertures arranged in a lateral area of the cap to allow insertion of at least one assembling tool for applying a force to move the at least one compliant sheath removal beam from the first position to the second position.

12. The auto-injector according to claim 1 , wherein the medicament container is held in the case.

13. The auto-injector according to claim 12 , wherein the medicament container is a syringe.

14. The auto-injector of claim 3 , wherein, when the cap is removed, the needle shroud translates in the distal direction relative to the case until the shroud rib abuts the first plunger boss.

15. An auto-injector comprising:

a case adapted to hold a medicament container having a needle;

a needle shroud telescopically coupled to the case and movable between a first extended position relative to the case in which the needle is covered and a retracted position relative to the case in which the needle is exposed;

a shroud spring biasing the needle shroud in a distal direction relative to the case; and

a cap removably coupled to the case, wherein the cap includes at least one compliant case beam adapted to releasably engage at least one aperture in the case, wherein, when the cap is moved in the distal direction relative to the case, the at least one compliant case beam disengages the at least one aperture in the case and no longer radially abuts the case, wherein a force required to disengage the at least one compliant case beam from the respective aperture is greater than a force exerted by the shroud spring on the cap when the compliant case beam is engaged in the aperture,

wherein the autoinjector comprises a first shroud lock mechanism which is arranged to prevent retraction of the needle shroud relative to the case when the cap is in place, thereby avoiding unintentional activation of the autoinjector,

wherein the first shroud lock mechanism comprises one or more compliant shroud beams on the cap and a respective number of apertures in the needle shroud adapted to receive each of the compliant shroud beams, wherein the one or more compliant shroud beams are different from the at least one compliant case beam,

wherein, when the cap is in place, the shroud spring is in an at least slightly loaded state, and

wherein the load of the shroud spring is statically resolved between the case and the shroud which are coupled through the compliant case beams and the compliant shroud beams on the cap.