PRINT HEAD

Abstract

It is an object of this invention to provide a print head which can stably eject ink droplets of large volume without being influenced by negative pressure variations in an ink supply source or by drive conditions. To this end the ink jet print head of this invention includes a plurality of nozzle openings to eject ink, a plurality of liquid paths communicating with these nozzle openings, and energy generation portion to eject ink supplied to each liquid path from each nozzle opening in the form of an ink droplet. In a part of each liquid path, a dividing portion to divide the liquid path into a plurality of paths is installed inward of the nozzle opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically illustrating a construction of a nozzle opening and its associated components in a print head of this invention;

FIG. 2A is a longitudinally sectioned side view illustrating a construction of nozzle openings and liquid paths communicating with them in the print head;

FIG. 2B is a cross-sectional view taken along the line B-B of FIG. 2A;

FIG. 2C is a front view illustrating a construction of nozzle openings and liquid paths communicating with them in the print head;

FIG. 3A to FIG. 3E are conceptual diagrams illustrating an ink ejection process in the print head of FIG. 1 and FIG. 2A;

FIG. 4 is a cross-sectional view illustrating an example print head according to a second embodiment of this invention;

FIG. 5 is a cross-sectional view illustrating another example of the print head in the second embodiment of this invention;

FIG. 6A is a longitudinally sectioned side view schematically illustrating a construction of nozzle openings and liquid paths communicating with them in a print head according to a third embodiment of this invention;

FIG. 6B is a cross-sectional view taken along the line B-B of FIG. 6A;

FIG. 6C is a front view schematically illustrating a construction of nozzle openings and liquid paths communicating with them in the print head of the third embodiment of this invention;

FIG. 7A is a perspective view schematically illustrating how a movable valve is displaced as a bubble is formed in ink in the print head of FIG. 6A;

FIG. 7B is a longitudinally sectioned side view schematically illustrating how the movable valve is displaced as a bubble is formed in ink in the print head of FIG. 6A;

FIG. 8A is a conceptual diagram, as seen from the front, illustrating how the movable valve is displaced before and after a bubble is formed in ink in the print head of FIG. 6A, with the bubble yet to emerge;

FIG. 8B is a conceptual diagram, as seen from the front, illustrating how the movable valve is displaced before and after a bubble is formed in ink in the print head of FIG. 6A, with the bubble emerging;

FIG. 9 is a perspective view schematically illustrating a construction of a nozzle opening and its associated components in a print head of another embodiment of this invention;

FIG. 10 is a perspective view schematically illustrating a construction of a nozzle opening and its associated components in a conventional print head;

FIG. 11A is a longitudinally sectioned side view schematically illustrating a construction of nozzle openings and liquid paths communicating with them in the conventional print head;

FIG. 11B is a cross-sectional view taken along the line B-B of FIG. 1A;

FIG. 11C is a front view schematically illustrating a construction of nozzle openings and liquid paths communicating with them in the conventional print head;

FIG. 12 is a perspective view schematically illustrating a construction of nozzle openings and their associated components in the conventional print head with two square nozzle openings arranged side by side;

FIG. 13 is a perspective view schematically illustrating a construction of nozzle openings and their associated components in the conventional print head with its large square nozzle opening divided by a partition plate; and

FIG. 14 is a side view schematically illustrating an example of an ink jet printing apparatus.

Claims

1. A print head comprising: a plurality of nozzle openings to eject ink;a plurality of liquid paths communicating with the nozzle openings; anda plurality of energy generation means to generate an ejection energy for ejecting the ink supplied to each liquid path from each nozzle opening in the form of droplet;wherein a dividing portion to divide a part of each liquid path into a plurality of paths is provided in an inward part of each liquid path.

2. A print head according to claim 1, wherein the liquid paths are formed by a heater board, a nozzle forming member and a top plate facing the heater board, the heater board holding heaters to generate a thermal energy as the ejection energy, the nozzle forming member being disposed between the heater board and the top plate;wherein the nozzle forming member has formed therein the plurality of nozzle openings and dividing portions and, in combination with the heater board, liquid paths.

3. A print head according to claim 1, wherein the dividing portion is formed of at least a flat plate provided in the liquid path.

4. A print head according to claim 3, wherein the dividing portion is formed in the liquid path between the nozzle opening and the heater.

5. A print head according to claim 3, wherein the dividing portion has a tapered portion that decreases in thickness toward the nozzle opening side.

6. A print head according to claim 3, wherein the dividing portion has a tapered portion that decreases in thickness toward the nozzle opening side and toward the heater side.

7. A print head according to claim 2, further including a movable valve that allows a bubble formed in the ink by heat from the heater to grow in the direction of ink ejection.