Inkjet head

An embodiment of the present invention provides an inkjet head including: a head body having a storage chamber capable of storing ink; a first inlet pipe and a second inlet pipe connected to the head body and which extend in first different directions and inject the ink in the first different directions; a first outlet pipe and a second outlet pipe connected to the head body and which extend in second different directions and eject the ink in the second different directions; and a nozzle plate positioned under the head body and which includes a plurality of nozzles.

This application claims priority to Korean Patent Application No. 10-2021-0146702, filed on Oct. 29, 2021, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference.

BACKGROUND

(a) Technical Field

The present disclosure relates to an inkjet head.

(b) Description of the Related Art

An inkjet device includes an inkjet head having a nozzle for ejecting ink. The inkjet head may eject ink from a plurality of nozzle holes formed in a nozzle surface. The inkjet head may form wires of a display panel, a color filter, or various thin films such as spacers by ejecting a conductive material, a color filter material, a curable material, or an insulating material as ink onto a substrate.

The ink may contain particles for each of the materials described above together with a solvent.

SUMMARY

Particles in ink have a relatively large specific gravity and settle easily in an inkjet head.

Embodiments have been made in an effort to prevent defects such as spots of an image by preventing functional deviation of a thin film of a display panel printed using an inkjet head by preventing a concentration of ejected ink from being changed depending on a position of a nozzle due to non-uniform settling and dispersion of ink particles in the inkjet head.

In addition, the embodiments have been made in an effort to reduce an ink material cost by preventing wastage of an ink material by preventing unnecessary operations such as ink purge to control concentration dispersion of ink ejected from the nozzle of the inkjet head.

An embodiment of the present invention provides an inkjet head including: a head body having a storage chamber capable of storing ink; a first inlet pipe and a second inlet pipe connected to the head body and which extend in first different directions and inject the ink in the first different directions; a first outlet pipe and a second outlet pipe connected to the head body and which extend in second different directions and ejecting the ink in the second different directions; and a nozzle plate positioned under the head body and which includes a plurality of nozzles.

The first inlet pipe and the second inlet pipe may be positioned at a first end of the head body, and the first outlet pipe and the second outlet pipe may be positioned at a second end of the head body facing the first edge.

The first inlet pipe and the first outlet pipe may extend in a first direction, and the second inlet pipe and the second outlet pipe may extend in a second direction that is perpendicular to the first direction.

The inkjet head may further include a first filter and a second filter positioned within the storage chamber and which extend in third different directions.

The first filter may extend parallel to the nozzle plate, and may overlap the first inlet pipe and the first outlet pipe in a plan view, and the second filter may be positioned inside the second inlet pipe, and may overlap the second inlet pipe in a direction in which the second inlet pipe extends.

The first filter may be positioned below the first inlet pipe and the first outlet pipe and above the second inlet pipe and the second outlet pipe.

The inkjet head may further include a third filter positioned in the storage chamber and spaced apart from an inner surface of the head body.

The third filter may be connected to the first filter and the second filter, and the third filter may be extended in a direction in which the second filter is extended.

The inkjet head may further include a cover plate positioned within the storage chamber and between the first filter and the nozzle plate, and the cover plate may be positioned below the second inlet pipe and overlaps the nozzles on the plan view.

The cover plate may include a pair of edge portions adjacent to opposite edges of an inner surface of the head body in the second direction, and a central portion positioned between the pair of edge portions and connected to the pair of edge portions, and a width of the central portion in a third direction may be smaller than a width of the edge portions in the third direction.

The edge portions may be in contact with the inner surface of the head body, and the central portion may be spaced apart from the inner surface of the head body.

The cover plate may define one or more holes therein.

The holes may not overlap the nozzles in the plan view.

The cover plate may have a mesh or net shape.

The inkjet head may further include: a first flow controller positioned on a lower, inner surface of the head body and which does not overlap the nozzles in the plan view, and the first flow controller may be positioned between a side, inner surface of the body and an outer nozzle row among a plurality of nozzle rows in which the nozzles are arranged, and the first flow controller may extend along the outer nozzle row.

The inkjet head may further include a second flow controller positioned on the lower, inner surface of the head body and which does not overlap the nozzles in the plan view, and the second flow controller may be positioned between two adjacent inner nozzle rows positioned inside among the nozzle rows, and the second flow controller may extend along the inner nozzle rows.

The first flow controller and the second flow controller may have a pointed top, and a height of the second flow controller may be greater than a height of the first flow controller.

An embodiment of the present invention provides an inkjet head including: a head body having a storage chamber capable of storing ink; a first inlet pipe and a second inlet pipe connected to the head body; a first outlet pipe and a second outlet pipe connected to the head body; a nozzle plate positioned under the head body and which includes a plurality of nozzles; and a first filter and a second filter positioned within the storage chamber and which extend in different directions, where the first filter extends parallel to the nozzle plate and overlaps the first inlet pipe in a plan view, the second filter is positioned inside the second inlet pipe, and overlaps the second inlet pipe in a direction in which the second inlet pipe extends, and the ink includes at least one of quantum dots or scatterers.

An embodiment of the present invention provides an inkjet head including: a head body having a storage chamber capable of storing ink; one or more inlet pipes and one or more outlet pipes connected to the head body; a nozzle plate positioned under the head body and which includes a plurality of nozzles; a filter positioned in the storage chamber and which overlaps the inlet pipe; and a cover plate positioned within the storage chamber and between the filter and the nozzle plate, where the cover plate overlaps the nozzles in a plan view, and the cover plate defines one or more holes therein.

An embodiment of the present invention provides an inkjet head including: a head body having a storage chamber capable of storing ink; one or more inlet pipes and one or more outlet pipes connected to the head body; a nozzle plate positioned under the head body and which includes a plurality of nozzles; and a first flow controller and a second flow controller positioned on a lower, inner surface of the head body and which does not overlap the nozzles in a plan view, where the first flow controller is positioned between a side, inner surface of the body and an outer nozzle row among a plurality of nozzle rows in which the nozzles are arranged, the first flow controller extends along the outer nozzle row, the second flow controller is positioned between two adjacent inner nozzle rows positioned inside among the nozzle rows, and the second flow controller extends along the inner nozzle rows.

The first flow controller and the second flow controller may have a pointed top, and a height of the second flow controller may be greater than a height of the first flow controller.

According to the embodiments, it is possible to effectively prevent defects such as spots of an image by preventing functional deviation of a thin film of a display panel printed using an inkjet head by preventing a concentration of ejected ink from being changed depending on a position of a nozzle due to non-uniform sedimentation and dispersion of ink particles in the inkjet head.

In addition, according to the embodiments, it is possible to reduce an ink material cost by preventing wastage of an ink material by preventing unnecessary operations such as ink purge to control concentration dispersion of ink ejected from the nozzle of the inkjet head.

DETAILED DESCRIPTION

To clearly describe the present invention, parts that are irrelevant to the description are omitted, and like numerals refer to like or similar constituent elements throughout the specification.

Further, since sizes and thicknesses of constituent members shown in the accompanying drawings are arbitrarily given for better understanding and ease of description, the present invention is not limited to the illustrated sizes and thicknesses. In the drawings, the thicknesses of layers, films, panels, regions, etc., are exaggerated for clarity. In the drawings, for better understanding and ease of description, the thicknesses of some layers and areas are exaggerated.

Further, in the specification, the phrase “in a plan view” means when an object portion is viewed from above (i.e., view in a z direction), and the phrase “in a cross-sectional view” means when a cross-section taken by vertically cutting an object portion is viewed from the side.

An inkjet head according to an embodiment will be described with reference toFIG.1toFIG.4.

FIG.1andFIG.2each illustrate a top plan view of an inkjet head according to an embodiment,FIG.3illustrates a cross-sectional view of the inkjet head illustrated inFIG.1taken along line A1-A2, andFIG.4illustrates a cross-sectional view of the inkjet head illustrated inFIG.1taken along line B1-B2.

An inkjet head1000according to an embodiment includes a head body800, a plurality of inlet pipes310pand330p, a plurality of outlet pipes320pand340p, a nozzle plate100, a first filter410, a second filter420, and a cover plate500.

The head body800has a storage chamber810capable of storing ink. The head body800has an inner surface801.

The ink to be stored in the storage chamber810may vary depending on purpose of an inkjet device including an inkjet head. For example, the ink may include a conductive material, a color filter material, a curable material, an insulating material, an emission layer material, or a color conversion layer material, and various films such as wires of a display panel, color filters, spacers, and emission layers may be formed by ejecting ink onto substrate.

The emission layer material or the color conversion layer material included in the ink may include, e.g., a semiconductor nano-crystal, and the semiconductor nanocrystal may include at least one of a phosphor, a quantum dot, or a scatterer. The quantum dot may have a core-shell structure including a core including semiconductor nanocrystals and a shell surrounding the core.

The ink contains particles for each of the materials described above together with a solvent.

The inlet pipes may include a first inlet tube310pand a second inlet pipe330peach having inlets for injecting ink in different directions, and the outlet pipes may include a first outlet pipe320pand a second outlet pipe340phaving outlets for ejecting ink in different directions.

The first inlet pipe310phas a first inlet310through which ink may be injected. The first inlet pipe310pmay be positioned at a side (e.g., top side of the head body800) facing the nozzle plate100, and may be positioned at an end (e.g., left end) of the head body800. The first inlet310and the first inlet pipe310pmay extend in a z direction, but the present invention is not limited thereto. The first inlet310is connected to the storage chamber810.

The first outlet pipe320phas a first outlet320through which ink may be ejected. The first outlet pipe320pmay be positioned at a side (e.g., top side of the head body800) facing the nozzle plate100, and may be positioned at an end (e.g., right end) opposite to the end (e.g., left end) where the first inlet pipe310pis positioned among ends of the head body800. The first outlet320and the first outlet pipe320pmay extend in the z direction, but the present invention is not limited thereto. The first outlet320is connected to the storage chamber810.

The second inlet pipe330phas a second inlet330through which ink may be injected. The second inlet pipe330pmay be positioned at the end (e.g., left end) of the head body800in which the first inlet pipe310pis positioned. The second inlet330and the second inlet pipe330pmay extend in a y-direction perpendicular to the z-direction, but the present invention is not limited thereto. The second inlet330is connected to the storage chamber810.

The second outlet pipe340phas a second outlet340through which ink may be ejected. The second outlet pipe340pmay be positioned at an end (e.g., right end) of the head body800where the first outlet pipe320pis positioned, and may be positioned to face the second inlet pipe330p. The second outlet340and the second outlet pipe340pmay extend in they direction, but the present invention is not limited thereto. The second outlet340is connected to the storage chamber810.

The first inlet pipe310pand the second inlet pipe330pare positioned at a first end (e.g., left end) of the head body800, and the first outlet pipe320pand the second outlet pipe340pmay be positioned at a second end (e.g., right end) of the head body800facing the first end.

The nozzle plate100is positioned under the head body800, and includes (in other words, “defines”) a plurality of nozzles110that are holes through which ink10can be ejected downward.

The nozzles110may be arranged to form a plurality of nozzle rows115a,115b,115c, and115don an xy plane (i.e., plane defined by x direction and y direction). As used herein, the “nozzle row” means a row of nozzles. The nozzle rows115a,115b,115c, and115deach may extend in the y direction. Referring toFIG.1andFIG.2, an example in which the nozzles110are arranged to form four nozzle rows115a,115b,115c, and115dis illustrated, but the number of nozzle rows according to the invention is not limited thereto.

A piezoelectric element200may be positioned on the nozzle plate100and between the adjacent nozzles110. When a driving signal is applied to the piezoelectric element200, the nozzle110may be contracted or expanded to easily eject ink by deformation of the piezoelectric element200.

The first inlet pipe310p, the first outlet pipe320p, the second inlet pipe330p, the second outlet pipe340p, and the nozzle plate100may be formed in or connected to the head body800to form the inkjet head1000in a bonded form.

The nozzle plate100is positioned at a bottom of the head body800, and the first inlet pipe310p, the first outlet pipe320p, the second inlet pipe330p, and the second outlet pipe340pare positioned above the nozzle plate100. The second inlet pipe330pand the second outlet pipe340pmay be positioned below the first inlet pipe310pand the first outlet pipe320p, respectively. Herein, up and down directions are based on the z direction, and are the same hereafter.

The first filter410is positioned in the storage chamber810, may extend parallel to the xy plane, and may be parallel to the nozzle plate100. Referring toFIG.1andFIG.3, the first filter410may overlap most of an interior space of the head body800in a top plan view. In this case, as illustrated inFIG.1andFIG.3, an edge of the first filter410may be in contact with an inner surface801of the head body800.

The storage chamber810may be divided into an upper area and a lower area with respect to the first filter410as a boundary.

The first filter410may be positioned below the first inlet pipe310pand the first outlet pipe320pand above the second inlet pipe330pand the second outlet pipe340p. The first filter410may overlap the first inlet pipe310pand the first outlet pipe320pin a top plan view.

The first filter410may block impurities other than particles11of an ink material injected from the first inlet310, and then may pass the ink to a lower side of the first filter410. To this end, the first filter410may have a hole sized enough to pass the particles11of the ink material and to block impurities larger than the particles11.

The ink that is injected as indicated by a straight arrow pointing down in the z direction inFIG.3andFIG.4may move downward through the first filter410after impurities are removed, and the impurities may move along the straight arrow in the y direction on the first filter410inFIG.3along the first filter410and may again be externally ejected through the first outlet320as indicated by a straight arrow pointing upward in the z direction.

The first filter410may be omitted in a certain embodiment.

The second filter420is positioned in the storage chamber810, and may extend parallel to the xz plane (SeeFIG.3). The second filter420is positioned inside the second inlet330, and may be positioned at a boundary between the second inlet330and the storage chamber810. That is, the second filter420may overlap the second inlet330and the second inlet pipe330pon the xz plane (i.e., a view in y direction).

The second filter420may block injection of impurities other than the particles11of the ink material injected from the second inlet330, and then may send the ink to the storage chamber810. To this end, the second filter420may have a hole sized enough to pass the particles11of the ink material and to block impurities larger than the particles11.

The second filter420may have a same material and structure as those of the first filter410. The second filter420may be connected to or separated from the first filter410.

The ink that is injected as indicated by a straight arrow in the y-direction in the second inlet330inFIG.3may be injected to the storage chamber810after impurities are removed through the second filter420.

The cover plate500is positioned in the storage chamber810, and may extend parallel to the xy plane. The cover plate500may be positioned between the first filter410and the nozzle plate100, and positioned below the second inlet330.

Referring toFIG.1toFIG.4, the cover plate500may overlap the nozzles110on the xy plane (i.e., in a top plan view).

The cover plate500may block the particles11of the ink material injected to the storage chamber810from settling directly toward the nozzle110.

The cover plate500may have a continuous plane. The cover plate500may include opposite edge portions501and a central portion502therebetween on the xy plane (i.e., in the plan view). The central portion502may be connected to the pair of edge portions501, and may be integrally formed (i.e., monolithic) with the edge portions501.

The opposite edge portions501may be positioned in regions adjacent to left and right ends of the inner surface801of the head body800in which the first inlet310, the second inlet330, the first outlet320, and the second outlet340are positioned. The edge portions501may overlap the first inlet310or the first inlet pipe310p, and the first outlet320and the first outlet pipe320pon the xy plane (i.e., in the plan view).

The edge portions501may serve to block the ink, which is injected to or ejected from the storage chamber810through the first inlet310, the second inlet330, the first outlet320, or the second outlet340, from not-circulating and settling directly into the nozzle110.

Edges of the edge portions501may be in contact with the inner surface801of the head body800.

An x-directional width of the central portion502is smaller than an x-directional width of each of the edge portions501. As illustrated inFIG.1,FIG.2, andFIG.3, the central portion502is spaced apart from an inner wall of the head body800, and thus ink may flow toward the nozzle plate100through a space between the central portion502and the head body800.

Upper and lower edges of the central portion502inFIG.2may be spaced apart from the inner surface801of the head body800.

Without the second inlet330and the second outlet340, a circulating amount of the ink positioned under the first filter410may be reduced in the storage chamber810, and thus settling of ink particles may easily occur, and it is easy to cause a deviation in concentration of ink particles depending on a position of the nozzle110. Then, defects such as spots due to functional deviation of the thin film of the display panel formed using the inkjet head1000may occur.

However, according to the present embodiment, it is possible to improve circulation of ink in the storage chamber810by adding the second inlet330and the second outlet340in addition to the first inlet310and the first outlet320. Thus, it is possible to prevent non-uniform dispersion in the concentration of ink particles due to particles settling in the space between the cover plate500and the head body800. Resultantly, it is possible to effectively prevent non-uniformity of the concentration of the ink ejected depending on the position of the nozzle110by non-uniform settling and dispersion of the particles of the ink in the storage chamber810, and defects such as image spots may be reduced by preventing functional deviation of the thin film of the display panel formed by using the inkjet head1000according to the invention. In addition, there is no need to perform operations such as ink purge for controlling the concentration distribution of the particles11of the ink10, thereby preventing wastage of the ink material and reducing the ink material cost.

In addition, according to an embodiment, it is possible to prevent the particles of the ink injected, from directly descending to the nozzle110by the cover plate500.

The cover plate500may include a metal, but the present invention is not limited thereto.

According to another exemplary embodiment, the cover plate500may be omitted.

The second filter420between the second inlet330and the storage chamber810may reduce imbalance in purification of ink in the space between the first filter410and the nozzle plate100while blocking impurities in the ink.

Since the second inlet330is positioned on the cover plate500, it is possible to prevent ink vortex flow directly above the nozzle plate100and to prevent sedimentation of particles on the cover plate500.

An inkjet head according to another embodiment will be described with reference toFIG.5toFIG.7.

FIG.5illustrates a top plan view of an ink head according to another embodiment,FIG.6illustrates a cross-sectional view of the inkjet head illustrated inFIG.5taken along line A3-A4, andFIG.7illustrates a cross-sectional view of the inkjet head illustrated inFIG.5taken along line B3-B4.

An inkjet head1001according to the present embodiment is mostly the same as the inkjet head1000according to the embodiment illustrated inFIG.1toFIG.4described above, but may further include a first flow controller610and a second flow controller620, which are positioned in the storage chamber810and are formed on a bottom surface of the head body800(SeeFIG.7). InFIG.5, the line A3-A4is divided into two lines inside the head body800: an upper line passing through the second flow controller620, and a lower line passing through the nozzles110.

The first flow controller610and the second flow controller620do not overlap the nozzles110on the xy plane (i.e., in the top plan view).

The first flow controllers610may be positioned outside the nozzle rows115aand115dat opposite edges among the nozzle rows115a,115b,115c, and115d, i.e., between the outer nozzle row115aand the upper inner surface801of the head body800and between the outer nozzle row115dand the lower inner surface801inFIG.5.

The first flow controllers610each may be elongated in a direction in which the nozzle rows115aand115dextend, i.e., in the y-direction, and are adjacent to each of the nozzle rows115aand115dalong the nozzle rows115aand115d.

A cross-sectional structure of the first flow controller610viewed on the xz plane (i.e., view in the y direction inFIG.7) may have a substantially triangular shape with a pointed top, but the present invention is not limited thereto.

The second flow controllers620may be positioned between two inner nozzle rows115band115camong the nozzle rows115a,115b,115c, and115d. Particularly, the second flow controller620may be positioned in a center of the bottom surface of the head body800, and may be positioned between two adjacent nozzle rows115band115c. One or more second flow controllers620may be positioned between the two adjacent nozzle rows115band115c.FIG.5andFIG.7each illustrate an example in which two second flow controllers620are positioned between two adjacent nozzle rows115band115cin the center, but a number of second flow controllers620according to the invention is not limited thereto.

The second flow controllers620each may be elongated in a direction in which the nozzle rows115band115cextend, i.e., in the y-direction, and are adjacent to each of the nozzle rows115band115calong the nozzle rows115band115c.

A cross-section structure of the second flow controller620viewed on the xz plane (i.e., view in the y direction inFIG.7) may have a substantially triangular shape with a pointed top, but the present invention is not limited thereto.

A z-directional height of the second flow controller620in the z direction may be greater than a z-directional height of the first flow controller610. A cross-sectional size of the second flow controller620shown inFIG.7may be larger than a cross-sectional size of the first flow controller610.

The first flow controller610may prevent the ink10injected in a direction of the straight arrows inFIG.7from settling around the cover plate500and being directly ejected to the outer nozzle rows115aand115d. The second flow controller620that is larger than the first flow controller610may induce sedimentation of the particles11by blocking a flow of the particle11around the inner nozzle rows115band115cas indicated by the curved line arrows inFIG.7. Accordingly, it is possible to improve relatively lower concentration of the particles11of the ink10in a central region of the nozzle plate100than the concentration of the particles11in an edge region of the nozzle plate100close to the space between the cover plate500and the left and right sides of the head body800. Thus, the concentration of the particles11of the ink10passing through the nozzles110of the nozzle plate100may be made more uniform.

An inkjet head according to still another embodiment will be described with reference toFIG.8toFIG.10.

FIG.8illustrates a top plan view of an ink head according to still another embodiment,FIG.9illustrates a cross-sectional view of the inkjet head illustrated in FIG.8taken along line A5-A6, andFIG.10illustrates a cross-sectional view of the inkjet head illustrated inFIG.8taken along line B5-B6.

The inkjet head1002according to the present embodiment is mostly the same as the inkjet head1000or the inkjet head1001described above, but may include a cover plate510instead of the cover plate500.

The cover plate510may include (i.e., define) at least one hole52therein. The hole52may not overlap the nozzles110on the xy plane (i.e., in the plan view). Since the hole52does not overlap the nozzles110, particles11of ink10descending through the hole52may be prevented from settling directly into the nozzles110.

The at least one hole52may divide a central portion502into two or more regions.FIG.8illustrates an example in which one hole52divides the central portion502into two regions.

The particles11of the ink10may descend toward the nozzle plate100also through the hole52in the center of the cover plate510in addition to the space between the cover plate510and the left and right sides of the head body800as indicated by the curved arrows inFIG.10, and thus it is possible to relatively improve a lower concentration of the particles11of the ink10in a central region of the nozzle plate100than the concentration of the particles11in an edge region of the nozzle plate100close to the space between the cover plate510and the left and right sides of the head body800. Thus, the concentration of the particles11of the ink10passing through the nozzles110of the nozzle plate100may be made more uniform.

Referring toFIG.9andFIG.10, the cover plate510may have a mesh or net shape. Accordingly, the cover plate510may include a plurality of holes51. Each of the holes51is smaller than the hole52dividing the central portion502of the cover plate510. The hole51may be larger than or equal to a size of the particles11of the ink. Accordingly, circulation of the particles11of the ink10by the cover plate510may be further improved.

In addition, the characteristics of the cover plate500of the above-described embodiment may be equally applied to the cover plate510according to the present embodiment.

An inkjet head according to yet another embodiment will be described with reference toFIG.11toFIG.13.

FIG.11illustrates a top plan view of an ink head according to yet another embodiment,FIG.12illustrates a cross-sectional view of the inkjet head illustrated inFIG.11taken along line A7-A8, andFIG.13illustrates a cross-sectional view of the inkjet head illustrated inFIG.11taken along line B7-B8.

The inkjet head1003according to the present embodiment is mostly the same as the inkjet head1000, the inkjet head1001, and the inkjet head1002described above, but may further include a third filter430and a fourth filter440.

InFIG.11, the line A7-A8do not pass through the third filter430or the fourth filter440, but for convenience of understanding, the fourth filter440is illustrated inFIG.12.

The third filter430and the fourth filter440may be positioned in the storage chamber810, and each of them may extend parallel to the yz plane. The third filter430and the fourth filter440are positioned close to the opposite edges (i.e., left and right inner surfaces inFIG.13) of the head body800, respectively, and are spaced apart from the inner surface801of the head body800by an interval GP that is greater than 0. The third filter430and the fourth filter440may face each other with the cover plate510therebetween.

Referring toFIG.12andFIG.13, the third filter430and the fourth filter440may be parallel to the yz plane. That is, the third filter430and the fourth filter440may extend from an upper region to a lower region of the cover plate510and extend in the y direction in which the first filter410extends.

Unlike in the above-described embodiment, referring toFIG.11, upper and lower ends of the first filter410may be spaced apart from the inner surface801of the head body800. Such a distance may be equal to the interval GP.

The third filter430and the fourth filter440may be connected to at least one of the first filter410or the second filter420. In addition, the third filter430and the fourth filter440may be connected to the first filter410and the second filter420to form one overturned lid, and may overlap and cover the nozzles110at the bottom. The first filter410, the second filter420, the third filter430, and the fourth filter440connected to each other may form a cuboid shape with an open bottom, but the shape formed by the filters together is not limited thereto, and other shapes such as a dome may be formed in another embodiment.

The third filter430and the fourth filter440may have the same material and function as those of the first filter410or the second filter420. That is, the third filter430and the fourth filter440may pass the ink10toward the nozzle110after blocking impurities other than the particles11of the material of the ink10injected therein. To this end, the third filter430and the fourth filter440may have (i.e., define the hole therein) a hole sufficiently sized to pass the particles11of the ink material and to block impurities larger than the particles11.

The ink that is injected as indicated by a straight arrow inFIG.12andFIG.13may move toward the nozzle110through the first filter410, the second filter420, the third filter430, and the fourth filter440after the impurities are removed.

According to the present embodiment, the ink moves toward the nozzle plate100through the interval GP in the storage chamber810and passes through the third filter430and the fourth filter440, and thus circulation of the ink10in the storage chamber810may be further improved by reducing the number of particles of which circulation is stagnant after passing through the first filter410.

DESCRIPTION OF SYMBOLS