Automatically disabled syringe

1. A disabling system for a syringe, said disabling system comprising a plunger having at least one ratchet and a collar mountable to a barrel of said syringe, said collar comprising an inner member and an outer member having at least one pawl capable of engaging said ratchet, the inner member comprising one or more resiliently deformable projections initially positioned between the pawl of the outer member and the ratchet to prevent engagement of said ratchet by said at least one pawl until said plunger is depressed forcing the inner member out of engagement with the outer member to allow the pawl of the outer member to engage the ratchet.

2. The disabling system of claim 1 , wherein the plunger comprises two opposed ratchets, each disposed longitudinally along said plunger.

3. The disabling system of claim 2 , wherein each of said two opposed ratchets are alignable relative to two pawls so as to be capable of engaging said two pawls to prevent withdrawal of said plunger during or following depression of said plunger.

4. The disabling system of claim 3 , wherein each of said two opposed ratchets comprise a plurality of aligned steps, teeth or abutments.

5. The disabling system of claim 1 , wherein the inner member and the outer member are in use incapable of rotation relative to each other.

6. The disabling system of claim 5 , wherein said outer member comprises two fingers capable of slidably engaging respective, opposed guide slots located on said plunger to thereby prevent rotation of said plunger relative to said collar.

7. A syringe comprising a plunger comprising at least one ratchet, a barrel and a collar mountable to said barrel, said collar comprising an inner member and an outer member having at least one pawl, the inner member comprising one or more resiliently deformable projections initially positioned between the pawl of the outer member and the ratchet to prevent engagement of said ratchet by said at least one pawl until said plunger is depressed forcing the inner member out of engagement with the outer member to allow the pawl of the outer member to engage the ratchet.

8. The syringe of claim 7 , wherein the collar comprises two pawls.

9. The syringe of claim 8 , wherein the plunger comprises two opposed ratchets, each disposed longitudinally along said plunger.

10. The syringe of claim 9 , wherein said two opposed ratchets are respectively alignable with the two pawls so as to be capable of respectively engaging said pawls, in use to prevent withdrawal of said plunger during or following depression of said plunger.

11. The syringe of claim 10 , wherein each of said two opposed ratchets comprise a plurality of aligned steps, teeth or abutments.

12. The syringe of claim 7 , wherein the inner member and the outer member are incapable of rotation relative to each other.

13. The syringe of claim 12 , wherein said outer member comprises two fingers that slidably engage respective, opposed guide slots located on said plunger to thereby prevent rotation of said plunger relative to said collar.

14. A syringe comprising:

a barrel that comprises two pawls; and

a plunger comprising:

two opposed ratchets respectively engageable by said two pawls to prevent withdrawal of said plunger during or following depression of said plunger; and

two opposed guide slots;

wherein said barrel comprises a collar having an inner member and an outer member that are incapable of rotation relative to each other, the inner member comprising one or more resiliently deformable projections initially positioned between the pawl of the outer member and the ratchet to prevent engagement of said ratchet by said two pawls until said plunger is depressed forcing the inner member out of engagement with the outer member to allow the pawl of the outer member to engage the ratchet, said outer member comprising said two pawls and further comprising two fingers that respectively slidably engage said opposed guide slots of said plunger to thereby prevent rotation of said plunger relative to said collar.

15. A method of operating a syringe, said method comprising:

providing a syringe comprising a plunger including at least one ratchet, a barrel and a collar mountable to said barrel, said collar comprising an inner member and an outer member having at least one pawl, the inner member comprising one or more resiliently deformable projections initially positioned between the pawl of the outer member and the ratchet to prevent engagement of said ratchet by said two pawls until said plunger is depressed forcing the inner member out of engagement with the outer member to allow the pawl of the outer member to engage the ratchet; and

depressing said plunger from a first position at which said at least one pawl is not engageable with said at least one ratchet by at least one projection of the inner member positioned between the at least one pawl and the at least one ratchet to a second position at which said at least one pawl is engageable with said at least one ratchet to prevent withdrawal of said plunger.

16. A method of making a disabling system for a syringe, the method comprising:

forming at least one ratchet on a plunger; and

positioning an inner member of a collar which is mountable to a barrel of a syringe, the inner member comprising one or more resiliently deformable projections initially positioned between the pawl of the outer member and the ratchet to prevent engagement of the at least one ratchet of the plunger by at least one pawl of an outer member of the collar until the plunger is depressed forcing the inner member out of engagement with the outer member to allow the pawl of the outer member to engage the ratchet.

17. The method of claim 16 wherein the forming at least one ratchet on a plunger further comprises forming at least two ratchets which are disposed longitudinally along the plunger.

18. The method of claim 17 further comprising aligning each of the at least two ratchets relative to two of the at least one pawls for engagement following depression of the plunger.

19. The method of claim 18 wherein each of the two ratchets comprise a plurality of at least one of aligned steps, teeth and abutments.

20. The method of claim 16 wherein the inner member and the outer member of the collar are incapable of rotation relative to each other.

21. The method of claim 20 further comprising slidably engaging at least two fingers of the outer member in guide slots located on the plunger to prevent rotation of the plunger relative to the collar.

22. A method of making a syringe, the method comprising:

forming at least one ratchet on a plunger;

mounting a collar in a barrel, the collar comprising an inner member and an outer member having at least one pawl; and

mounting the plunger for movement in the barrel, the inner member comprising one or more resiliently deformable projections initially positioned between the pawl of the outer member and the ratchet to prevent initial engagement of the at least one ratchet by the at least one pawl until the plunger is depressed in the barrel forcing the inner member out of engagement with the outer member to allow the pawl of the outer member to engage the ratchet.

23. The method of claim 22 wherein the outer member has at least two of the pawls.

24. The method of claim 23 wherein the forming at least one ratchet on a plunger further comprises forming at least two ratchets which are disposed longitudinally along the plunger.

25. The method of claim 24 further comprising aligning each of the at least two ratchets relative to two of the at least one pawls for engagement following depression of the plunger.

26. The method of claim 25 wherein each of the two ratchets comprise a plurality of at least one of aligned steps, teeth and abutments.

27. The method of claim 26 wherein the inner member and the outer member are incapable of rotation relative to each other.

28. The method of claim 27 further comprising slidably engaging at least two fingers of the outer member in guide slots located on the plunger to prevent rotation of the plunger relative to the collar.