Restrictors with structure to prevent back flow and inkjet head having the same
View Patent ↗A restrictor with a structure to prevent a back flow of ink and an inkjet head including the restrictor. In the inkjet head, an ink channel is formed in a channel plate, and the ink channel includes an ink inlet, a plurality of pressure chambers, a manifold, a plurality of restrictors respectively connecting the pressure chambers to the manifold, and a plurality of nozzles. Piezoelectric actuators are formed on the channel plate. Each of the restrictors includes a plurality of protrusions formed on an inner surface thereof in a structure suitable to increase a flow resistance of the restrictor when ink flows from the pressure chamber to the manifold through the restrictor. Each of the protrusions includes a first surface facing a flow of ink moving through the restrictor in a direction from the manifold to the pressure chamber, and a second surface facing a flow of ink moving through the restrictor in a direction from the pressure chamber to the manifold. The first surface has a low flow resistance, and the second surface has a high flow resistance. Therefore, a black flow of ink is restricted when ink is ejected, and sufficient ink can be supplied through the restrictor during an ink refill process.
1. A restrictor to connect a pressure chamber and a manifold in an inkjet head, the restrictor comprising:
a plurality of protrusions formed on an inner surface of the restrictor in a structure suitable to increase a flow resistance of the restrictor when ink flows from the pressure chamber to the manifold through the restrictor.
2. The restrictor of claim 1 , wherein the protrusions extend inward from at least one of both sides of the restrictor and are arranged at predetermined intervals in a length direction of the restrictor.
3. The restrictor of claim 1 , wherein each of the protrusions comprises:
a first surface facing a flow of ink moving through the restrictor in a direction from the manifold to the pressure chamber; and
a second surface facing a flow of ink moving through the restrictor in a direction from the pressure chamber to the manifold.
4. The restrictor of claim 3 , wherein the first surface is inclined at an angle of 110° to 160° from a side surface of the restrictor, and the second surface makes an angle of 90° or less with the side surface of the restrictor.
5. The restrictor of claim 4 , wherein the first surface is inclined at an angle of 130° to 140° from the side surface of the restrictor.
6. The restrictor of claim 4 , wherein each of the protrusions has a triangular shape, and the second surface makes an angle of 60° to 90° with the side surface of the restrictor.
7. The restrictor of claim 4 , wherein each of the protrusions has a rod-like shape with a predetermined thickness.
8. The restrictor of claim 3 , wherein the first surface is curved, and a straight line drawn from a start point to an endpoint of the first surface makes an angle of 110° to 160° with a side surface of the restrictor.
9. The restrictor of claim 8 , wherein the straight line drawn from the start point to the endpoint of the first surface makes an angle of 130° to 140° with the side surface of the restrictor.
10. The restrictor of claim 8 , wherein the second surface is curved, and a straight line drawn from a start point to an endpoint of the second surface makes an angle of 90° or less with the side surface of the restrictor.
11. The restrictor of claim 10 , wherein the straight line drawn from the start point to the endpoint of the second surface makes an angle of 40° to 80°.
12. A piezoelectric inkjet head comprising:
an ink channel formed in a channel plate, the ink channel including an ink inlet, a plurality of pressure chambers, a manifold connected to the ink inlet, a plurality of restrictors respectively connecting the pressure chambers to the manifold, and a plurality of nozzles connected to the pressure chambers; and
piezoelectric actuators formed on the channel plate at positions respectively corresponding to the pressure chambers,
wherein each of the restrictors includes a plurality of protrusions formed on an inner surface thereof in a structure to increase a flow resistance of the restrictor when ink flows from the pressure chamber to the manifold through the restrictor.
13. The piezoelectric inkjet head of claim 12 , wherein the channel plate comprises a plurality of stacked substrates.
14. The piezoelectric inkjet head of claim 13 , wherein the channel plate comprises:
an upper substrate in which the pressure chambers and the ink inlet are formed;
a middle substrate in which the restrictors and the manifold are formed; and
a lower substrate in which the nozzles are formed,
wherein the restrictors are formed in a top surface of the middle substrate to a predetermined depth, and the protrusions extend inward from at least one of both sides of each of the restrictors and are arranged at predetermined intervals in a length direction of the restrictor.
15. The piezoelectric inkjet head of claim 12 , wherein each of the protrusions comprises:
a first surface facing a flow of ink moving through the restrictor in a direction from the manifold to the pressure chamber; and
a second surface facing a flow of ink moving through the restrictor in a direction from the pressure chamber to the manifold.
16. The piezoelectric inkjet head of claim 15 , wherein the first surface is inclined at an angle of 110° to 160° from a side surface of the restrictor, and the second surface makes an angle of 90° or less with the side surface of the restrictor.
17. The piezoelectric inkjet printhead of claim 16 , wherein each of the protrusions has a triangular shape, and the second surface makes an angle of 60° to 90° with the side surface of the restrictor.
18. The piezoelectric inkjet printhead of claim 16 , wherein each of the protrusions has a rod-like shape with a predetermined thickness.
19. The piezoelectric inkjet printhead of claim 15 , wherein the first and second surfaces are curved, wherein a straight line drawn from a start point to an endpoint of the first surface makes an angle of 110° to 160° with a side surface of the restrictor, and a straight line drawn from a start point to an endpoint of the second surface makes an angle of 90° or less with the side surface of the restrictor.
20. A piezoelectric inkjet head having a pressure chamber and a manifold, the inkjet head comprising:
a path connecting the pressure chamber and the manifold; and
a plurality of triangles subsequently formed along an inner surface of the path to increase a flow resistance of the path when ink flows from the pressure chamber to the manifold through the path.
21. The piezoelectric inkjet head of claim 20 , wherein sides of the triangles merge toward each other in a direction toward the pressure chamber from the manifold.
22. The piezoelectric inkjet head of claim 21 , wherein the sides of the path are formed in a sawtooth structure.
23. A piezoelectric inkjet head, comprising:
a pressure chamber;
a manifold; and
a path connecting the pressure chamber and the manifold, the path including opposing sides formed in a sawtooth shape to increase a flow resistance of the path when ink flows from the pressure chamber to the manifold through the path.