Ink supply system comprising pressure device and in-line valve

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

(a) an ink reservoir for storing ink;

(b) an ink conduit interconnecting said ink reservoir and said printhead;

(c) a pressure device for positively pressurizing said ink reservoir;

(d) a shut-off valve in said ink conduit for controlling a supply of ink to said printhead, said shut-off valve being positioned between said ink reservoir and said printhead;

(e) a controller for controlling operation of said pressure device and said shut-off valve; and

(f) a pressure sensor for measuring a pressure in said ink reservoir or said ink conduit, wherein said controller is configured to coordinate a printhead purge operation using said pressure device, said pressure sensor and said valve.

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 3 , wherein each ink conduit has a respective valve.

5. The ink supply system of claim 1 , wherein said valve is a solenoid valve.

6. The ink supply system of claim 1 , further comprising a controller for controlling operation of said pressure device and said valve.

7. The ink supply system of claim 1 , wherein said pressure sensor is in communication with said controller, said controller being configured to control said pressure device in response to feedback provided by said pressure sensor.

8. The ink supply system of claim 1 , wherein said controller is configured to coordinate the following steps in response to a request for printhead purging:

(i) close said valve;

(ii) pressurize said ink reservoir using said pressure device;

(iii) monitor a pressure in said ink reservoir or said ink conduit using said pressure sensor; and

(iv) open said valve for a predetermined period when a predetermined pressure has been reached.

9. The ink supply system of claim 1 , wherein said ink reservoir comprises a pressure-biasing means for biasing a pressure in said reservoir towards a negative pressure.

10. The ink supply system of claim 1 , wherein said pressure device comprises a compression mechanism for compressing said ink reservoir.

11. The ink supply system of claim 10 , wherein said ink reservoir comprises an ink bag containing ink.

12. The ink supply system of claim 11 , wherein said compression mechanism comprises a compression member for compressing abutment with a wall of said ink bag.

13. The ink supply system of claim 12 , wherein said compression member comprises a pressure plate.