Ink jet head and ink supplying method thereof

1. An inkjet head comprising:

an ink storage unit comprising an inner storage space storing ink; and

a head unit connected to the ink storage unit and including nozzles for discharging the ink, wherein a floor of the inner storage space of the ink storage unit includes a lower level and a higher level that is higher than the lower level, the lower level and the higher level respectively comprising a lower injection hole and an upper injection hole connected to the head unit.

2. The inkjet head of claim 1 , wherein the head unit comprises an inner flow space connecting the lower injection hole to the upper injection hole, and wherein

the lower injection hole and the upper injection hole are formed in an asymmetric arrangement in the inner flow space.

3. The inkjet head of claim 1 , wherein

the head unit comprises an inner flow space where the ink flows, and

a lower connection hole and an upper connection hole respectively connected to the lower injection hole and the upper injection hole are formed on the ceiling of the inner flow space.

4. The inkjet head of claim 3 , wherein

the lower connection hole is closer to a bottom of the inner flow space than the upper connection hole.

5. The inkjet head of claim 4 , wherein

the ceiling of the inner flow space is inclined.

6. The inkjet head of claim 5 , further comprising

an ink supplying hole formed at a sidewall of the inner storage space of the ink storage unit, wherein the ink supplying hole is disposed near the lower level of the floor and supplies the ink to the ink storage unit through the ink supplying hole.

7. The inkjet head of claim 6 , further comprising

a pressure controller formed on said ink storage unit controlling the size and shape of the meniscus formed by the ink droplet at the tip of the nozzles, and pushing said ink stored in said ink storage unit.

8. An ink supplying method of an inkjet head including an ink storage unit having an inner storage space storing ink, a head unit having an inner flow space connected to the ink storage unit and having nozzles for discharging the ink, a floor of the inner storage space including a lower level and a higher level that is higher than the lower level, and the lower level and higher level are respectively formed with a lower injection hole and an upper injection hole connected to the head unit, comprising:

providing a first supply of the ink at the lower level of the ink storage unit;

controlling the first supply of the ink such that the level of the ink is no higher than the higher level of the ink storage unit, thus preventing the ink from flowing into the inner storage space through the upper injection hole formed at the higher level;

repeating said first supply of the ink until said inner flow space in said head unit and said lower level of said inner storage space are filled with ink; and

providing a second supply of the ink at the ink storage unit when the ink flows into the ink storage unit through the upper injection hole and the flowing ink meets the ink filling the lower level of the ink storage unit.

9. The ink supplying method of claim 8 , wherein

the ink flowing into the head unit through the lower injection hole formed at the lower level flows out of the head unit through the upper injection hole formed at the higher level.

10. The ink supplying method of claim 9 , wherein

the ink flowing into the inner flow space of the head unit through the lower injection hole in the first supply flows out through the upper injection hole according to the inclined ceiling of the inner flow space in one direction.

11. The ink supplying method of claim 10 , wherein

the ink flows into the inner flow space of the head unit through both the lower injection hole and the upper injection hole in the second supply.

12. An inkjet printing system to form a thin film pattern on a substrate comprising:

an inkjet head comprising an ink storage unit including an inner storage space storing ink, the inkjet head further comprising a head unit, the head unit having an inner flow space connected to the ink storage unit and including nozzles for discharging the ink, wherein a floor of the inner storage space includes a lower level and a higher level that is higher than the lower level, the lower level and the higher level respectively comprising a lower injection hole and an upper injection hole connected to the head unit, and further wherein the ceiling of said inner flow space is inclined;

a transfer unit; and

a supplying unit.

13. The inkjet printing system of claim 12 , wherein said transfer unit comprises:

a support for positioning said inkjet head above said substrate by a predetermined distance;

a horizontal transfer part for transferring said inkjet head across the substrate in two directions essentially orthogonal to one another; and

a lifter for lifting said inkjet head above the substrate.

14. The inkjet printing system of claim 12 , wherein said supplying unit comprises:

a plurality of ink tanks storing ink; and

a supplying pipe for supplying ink from said ink tanks to said inkjet head.

15. The inkjet printing system of claim 14 wherein said plurality of ink tanks comprises at least a red ink tank, a blue ink tank, and a green ink tank.

16. A method for forming a color filter on a substrate, the method comprising:

using an inkjet printing system, said inkjet printing system comprising:

an inkjet head comprising an ink storage unit including an inner storage space storing ink, a head unit connected to the ink storage unit and including nozzles for discharging the ink, wherein a floor of the inner storage space includes a lower level and a higher level that is higher than the lower level, the lower level and the higher level respectively comprising a lower injection hole and an upper injection hole connected to the head unit, and further wherein the ceiling of said inner flow space is inclined;

a transfer unit; and

a supplying unit to supply said ink to said inkjet head;

transferring said inkjet head across said substrate using said transfer unit; and

dripping said ink from said inkjet head on a predetermined position between light blocking members on the substrate.