Ink supply system with hammer mechanism for variable purge volume/pressure

1. An ink supply system for an inkjet printhead comprising:

(a) an ink reservoir for storing ink;

(b) an ink conduit providing fluid communication between said ink reservoir and said printhead; and

(c) a hammer mechanism for compressing part of said ink conduit,

wherein said hammer mechanism comprises:

a hammer head for urging abutment with a wall of said part of said conduit

a spring-loading mechanism for priming said hammer head; and

a release mechanism for releasing a primed hammer head.

2. The ink supply system of claim 1 comprising a plurality of ink reservoirs.

3. The ink supply system of claim 2 , wherein each ink reservoir has a respective ink conduit providing fluid communication between each ink reservoir and said printhead.

4. The ink supply system of claim 1 , further comprising:

(d) a conduit expander for expanding said part of said ink conduit.

5. The ink supply system of claim 4 , wherein said conduit expander is positioned within said ink conduit.

6. The ink supply system of claim 5 , wherein said conduit expander is resiliently biased towards an expanded configuration.

7. The ink supply system of claim 5 , wherein said conduit expander comprises a diaphragm, a balloon or a spring.

8. The ink supply system of claim 4 , further comprising:

(e) a first valve in said ink conduit positioned between said ink reservoir and said conduit expander.

9. The ink supply system of claim 8 , further comprising:

(f) a second valve in said ink conduit positioned between said conduit expander and said printhead.

10. The ink supply system of claim 9 , wherein said first and second valves are pinch valves.

11. The ink supply system of claim 10 , further comprising a controller for controlling operation of said hammer mechanism, said first valve and said second valve.

12. The ink supply system of claim 11 , wherein said controller is configured to coordinate a printhead purge operation using said hammer mechanism, said first valve and said second valve.

13. The ink supply system of claim 1 , wherein a volume of said part of said conduit is defined by a position of said hammer head.

14. The ink supply system of claim 1 , wherein said spring-loading mechanism has a plurality of spring-loaded configurations.

15. The ink supply system of claim 14 , wherein each spring-loaded configuration has an associated printhead purging pressure.

16. The ink supply system of claim 14 , wherein each spring-loaded configuration has an associated printhead purging volume.

17. The ink supply system of claim 1 , further comprising a controller for controlling operation of said hammer mechanism.