Ink jet head and ink jet recording apparatus

1. An ink jet head for ejecting ink in a form of an ink droplet to fly the ink droplet toward a recording medium, comprising:

an ejection orifice substrate in which an ejection orifice adapted to eject therefrom the ink is bored;

a head substrate disposed at a predetermined distance from said ejection orifice substrate to define an ink passage between said ejection orifice substrate and said head substrate;

ejection control means for controlling the ejection of the ink from said ejection orifice;

an ink guide dike provided on a surface of said head substrate on a side of said ink passage to form an ink flow directed from an upstream side of said ejection orifice in said ink passage to said ejection orifice; and

an ink guide projection disposed on said head substrate so as to extend through a central portion of said ejection orifice with its tip being directed in a direction of the ejection of the ink,

wherein said ink guide dike is provided so as to contact said ink guide projection.

2. The ink jet head according to claim 1 , wherein said ink guide dike includes a surface inclining in a direction from said surface of said head substrate on the side of said ink passage to said ejection orifice substrate so as to lead from the upstream side of said ejection orifice in said ink passage toward a position of said ejection orifice.

3. The ink jet head according to claim 1 , further comprising:

an ink guide groove formed in a surface of said ejection orifice substrate on the side of said ink passage so as to lead from the upstream side of said ejection orifice in said ink passage to said ejection orifice.

4. The ink jet head according to claim 3 , wherein:

said ejection electrode is formed into a circular arc shape with its part of the electrode on the upstream side of said ejection orifice in said ink passage being removed; and

said ink guide groove is formed so as to extend through said removed portion of said ejection electrode to reach in depth a position nearer said recording medium than said ejection electrode formed in the position nearest said recording medium.

5. The ink jet head according to claim 1 , wherein:

the ink contains a solvent and color particles dispersed in said solvent;

said ejection control means is comprised of an ejection electrode; and

an electrostatic force is made to act on the ink by said ejection electrode to eject the ink in the form of the ink droplet, thereby flying the ink droplet toward said recording medium.

6. The ink jet head according to claim 5 , wherein:

said ejection orifice substrate includes an insulating substrate and at least one layer of said ejection electrode provided on a surface of at least one of a side of said ink passage of said insulating substrate and a side of said recording medium of said insulating substrate so as to surround a periphery of said ejection orifice.

7. The ink jet head according to claim 1 , wherein the ink passage has ink flow passing from a first side to a second side about the ejection orifice, and wherein the ink guide dike has a first portion to form the ink flow directed from the first side to said ejection orifice and a second portion to keep a stability of the ink flow directed from said ejection orifice to the second side.

8. The ink jet head of claim 7 , wherein the ink guide dike extends only in the directions of the first and second sides in said ink passage.

9. The ink jet head according to claim 1 , wherein a length of the ink guide dike is three or more times as large as a maximum height thereof.

10. An ink jet recording apparatus for recording an image corresponding to image data on a recording medium using an ink jet head for ejecting ink in a form of an ink droplet, said ink jet head comprising:

an ejection orifice substrate in which an ejection orifice adapted to eject therefrom the ink is bored;

a head substrate disposed at a predetermined distance from said ejection orifice substrate to define an ink passage between said ejection orifice substrate and said head substrate;

ejection control means for controlling the ejection of the ink from said ejection orifice;

an ink guide dike provided on a surface of said head substrate on a side of said ink passage to form an ink flow directed from an upstream side of said ejection orifice in said ink passage to said ejection orifice; and

an ink guide projection disposed on said head substrate so as to extend through a central portion of said ejection orifice with its tip being directed in a direction of the ejection of the ink,

wherein said ink guide dike is provided so as to contact said ink guide projection.

11. The ink jet recording apparatus according to claim 10 , wherein said ink guide dike includes a surface inclining in a direction from said surface of said head substrate on the side of said ink passage to said ejection orifice substrate so as to lead from the upstream side of said ejection orifice in said ink passage toward a position of said ejection orifice.

12. The ink jet recording apparatus according to claim 10 , further comprising:

an ink guide groove formed in a surface of said ejection orifice substrate on the side of said ink passage so as to lead from the upstream side of said ejection orifice in said ink passage to said ejection orifice.

13. The ink jet recording apparatus according to claim 12 , wherein:

said ejection electrode is formed into a circular arc shape with its part of the electrode on the upstream side of said ejection orifice in said ink passage being removed; and

said ink guide groove is formed so as to extend through said removed portion of said ejection electrode to reach in depth a position nearer said recording medium than said ejection electrode formed in the position nearest said recording medium.

14. The ink jet recording apparatus according to claim 10 , wherein:

the ink contains a solvent and color particles dispersed in said solvent;

said ejection control means is comprised of an ejection electrode; and

an electrostatic force is made to act on the ink by said ejection electrode to eject the ink in the form of the ink droplet, thereby flying the ink droplet toward said recording medium.

15. The ink jet recording apparatus according to claim 14 , wherein:

said ejection orifice substrate includes an insulating substrate and at least one layer of said ejection electrode provided on a surface of at least one of a side of said ink passage of said insulating substrate and a side of said recording medium of said insulating substrate so as to surround a periphery of said ejection orifice.

16. An ink jet head for ejecting ink in a form of an ink droplet to fly the ink droplet toward a recording medium, comprising:

an ejection orifice substrate in which an ejection orifice adapted to eject therefrom the ink is bored;

a head substrate disposed at a predetermined distance from said ejection orifice substrate to define an ink passage between said ejection orifice substrate and said head substrate;

ejection control means for controlling the ejection of the ink from said ejection orifice;

an ink guide dike provided on a surface of said head substrate on a side of said ink passage to form an ink flow directed from an upstream side of said ejection orifice in said ink passage to said ejection orifice; and

an ink guide groove formed in a surface of said ejection orifice substrate on the side of said ink passage so as to lead from the upstream side of said ejection orifice in said ink passage to said ejection orifice.

17. An ink jet recording apparatus for recording an image corresponding to image data on a recording medium using an ink jet head for ejecting ink in a form of an ink droplet, said ink jet head comprising:

an ejection orifice substrate in which an ejection orifice adapted to eject therefrom the ink is bored;

a head substrate disposed at a predetermined distance from said ejection orifice substrate to define an ink passage between said ejection orifice substrate and said head substrate;

ejection control means for controlling the ejection of the ink from said ejection orifice;

an ink guide dike provided on a surface of said head substrate on a side of said ink passage to form an ink flow directed from an upstream side of said ejection orifice in said ink passage to said ejection orifice; and

an ink guide groove formed in a surface of said ejection orifice substrate on the side of said ink passage so as to lead from the upstream side of said ejection orifice in said ink passage to said ejection orifice.