Inkjet Printhead

Abstract

SOLUTION: Disclosed is an inkjet printhead. The inkjet printhead with multiple nozzles to eject a liquid solution by an electrohydrodynamic method includes: a first electrode which is formed for each of the nozzles and to which a voltage for ejecting the liquid solution by the electrohydrodynamic method is applied; a first voltage controller configured to apply the voltage to the first electrode; and a second electrode placed between and spaced from the first electrodes formed in the respective nozzles and grounded to inhibit electric field interference between the nozzles.EFFECT: The inkjet printhead has advantages of minimizing electric field interference between neighboring nozzles while ejecting droplets through the multiple nozzles by an electrohydrodynamic method, thereby making it possible to eject the droplets uniformly with easy control.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an inkjet printhead, and more particularly to an inkjet printhead having a plurality of nozzles and ejecting a solution by an electro-hydraulic method. [Background technology]

[0002] In general, an inkjet printhead is a device that prints an image of a predetermined color on a surface of a printing medium by ejecting minute droplets of ink onto a desired position on the printing medium. Recently, the application range of the inkjet printhead has been expanded to various fields such as flat display fields such as liquid crystal displays (LCDs) and organic light emitting devices (OLEDs), flexible display fields such as e-paper, printed electronics fields such as metal wiring, and biotechnology fields.

[0003] Drop-on-demand (DOD) type inkjet printheads include piezoelectric inkjet printheads that eject ink using pressure waves caused by deformation of a piezoelectric material according to the ejection method, and electrohydrodynamic inkjet printheads that eject ink using electrostatic force.

[0004] A piezoelectric inkjet printhead vibrates a membrane with a piezoelectric material to apply pressure to a chamber that contains ink, thereby ejecting ink. In general, droplets are ejected when pressure is applied that overcomes the surface tension and viscosity of the ink on the nozzle surface, and the additional pressure must be large enough to accelerate the ejected droplets to a speed that allows the droplets to land accurately on the print medium. In a piezoelectric inkjet printhead, it is necessary to reduce the amount of deformation energy in the pressure chamber to realize droplets of less than a few picoliters, but in this case, the ejection energy per unit volume of the ejected droplets is also reduced, resulting in a reduction in the ejection speed of the droplets. If the ejection speed of the droplets is reduced in this way, a problem occurs in that the droplets cannot be ejected accurately at the desired position.

[0005] Piezoelectric inkjet printheads have the advantage that it is easy to control the printing operation and there is no restriction on the ink used because the ejection energy is provided by the mechanical deformation of the piezoelectric body. However, piezoelectric inkjet printheads have difficulty in realizing ultra-fine droplets of less than a few picoliters, and are limited in that they can only eject ink with a viscosity of 10 cPs and cannot eject ink with high viscosity. In addition, due to the limit of the ejection energy, it is difficult to eject large droplets of more than 80 picoliters. In particular, unlike conventional graphic printing, the uniformity of the volume of ejected droplets between multiple nozzles is very important for application to printed electronic processes such as displays, but piezoelectric inkjet printheads have limitations.

[0006] Inkjet printheads using the electrohydrodynamic inkjet method provide ejection energy by applying electrostatic force to the ink surface formed at the tip of the nozzle, so they can realize ultra-fine droplets of less than a few picoliters or femtoliters, and can eject high-viscosity ink droplets of 1,000 cPs. They can also form large droplets of 80 picoliters or more. As they are controlled using the distribution of the electric field formed in the nozzle, the driving method is simple and the directionality of the ejected ink droplets is excellent, making them advantageous for precision printing.

[0007] However, when multiple nozzles are formed in an inkjet print head using the electro-hydrodynamic inkjet method, electric field interference occurs between adjacent nozzles, causing the size of droplets ejected through the multiple nozzles to be non-uniform, resulting in a problem of reduced print quality. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent No. 1310759 Summary of the Invention [Problem to be solved by the invention]

[0009] Accordingly, an object of the present invention is to provide an inkjet printhead having a plurality of nozzles for ejecting droplets by an electro-hydrodynamic method, in which a second electrode grounded between first electrodes formed in each nozzle for ejecting droplets by an electro-hydrodynamic method is spaced apart, thereby preventing electric field interference between each nozzle.

[0010] The problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0011] The above objects can be achieved by an inkjet printhead having a plurality of nozzles and ejecting a solution in an electro-hydraulic manner, comprising: a first electrode formed for each of the plurality of nozzles and to which a voltage for ejecting the solution in an electro-hydraulic manner is applied; a first voltage controller applying a voltage to the first electrode; and a second electrode disposed at a distance between the first electrodes formed in each of the nozzles and grounded to prevent electric field interference between the nozzles.

[0012] Here, the inkjet printhead may include a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored, and a nozzle layer having nozzle holes formed at lower ends of the nozzle chambers to eject the solution, the first electrode being formed on an inner surface of the nozzle chamber, and the second electrode being formed on an upper surface of the nozzle layer.

[0013] Here, it is preferable that the distance between the first electrode and the second electrode is greater than the distance between the lower end of the nozzle and the substrate to be printed.

[0014] Here, the inkjet printhead may include a nozzle layer having a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored and nozzle holes for ejecting a solution at lower ends of the nozzle chambers, a groove dug downwardly formed on an upper side of the nozzle layer, and the second electrode may be formed inside the groove.

[0015] Here, the semiconductor device may further include a blocking portion made of an insulator, covering the groove to block exposure of the second electrode to the outside of the groove.

[0016] Here, the inkjet printhead may include a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored, and a nozzle layer having nozzle holes formed at lower ends of the nozzle chambers to eject the solution, the first electrode being formed on an inner surface of the nozzle chamber, and the second electrode being formed on a lower surface of the nozzle layer.

[0017] Here, a protrusion may be formed at a lower end of the nozzle layer for each of the nozzles, the protrusion having the nozzle hole at its lower end, and the second electrode may be formed on a concave surface between the protrusions.

[0018] Here, it is preferable that the distance between the bottom end of the nozzle and the second electrode is greater than the distance between the bottom end of the nozzle and the substrate to be printed.

[0019] Here, the inkjet printhead may include a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored, and a nozzle layer having nozzle holes formed at lower ends of the nozzle chambers for ejecting the solution, a groove extending upward may be formed on a lower surface of the nozzle layer, and the second electrode may be formed inside the groove.

[0020] Here, the semiconductor device may further include a blocking portion made of an insulator, covering the groove to block exposure of the second electrode to the outside of the groove.

[0021] Here, the inkjet printhead may include a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored, a nozzle layer in which nozzle holes for ejecting the solution are formed at lower ends of the nozzle chambers, and a separation layer disposed on an upper portion of the nozzle layer and having a flow path formed therethrough and connected to the nozzle chambers, wherein the first electrode is formed on an inner surface of the nozzle chamber, and the second electrode is formed on an upper surface of the separation layer.

[0022] Here, the second electrode may also be formed on a lower surface of the nozzle layer.

[0023] Here, the inkjet printhead may include a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored, a nozzle layer in which nozzle holes for ejecting the solution are formed at lower ends of the nozzle chambers, and a separation layer disposed on an upper portion of the nozzle layer and having a flow path formed therethrough and connected to the nozzle chambers, wherein a groove is formed downward on an upper surface of the separation layer, and the second electrode may be formed inside the groove.

[0024] Here, the semiconductor device may further include a blocking portion made of an insulator, covering the groove to block exposure of the second electrode to the outside of the groove.

[0025] Here, the nozzle layer may include a first nozzle layer in which a plurality of nozzle chambers in which the ink supplied to each of the nozzles is stored and the nozzle holes for ejecting the solution are formed at lower ends of the nozzle chambers, and the first electrodes are formed on inner surfaces of the nozzle chambers; and a second nozzle layer formed on an upper portion of the first nozzle layer, in which a plurality of communication chambers linked to the nozzle chambers are formed, and a third electrode to which a voltage for ejecting the solution in an electro-hydraulic manner is applied is formed on an inner surface of the communication chambers.

[0026] Here, the plurality of nozzles may be arranged in a matrix, and the first electrodes arranged in one direction, either a row direction or a column direction, may be electrically connected to each other, and a voltage may be selectively and simultaneously applied to the first electrodes arranged in one direction by the first voltage controller, and the third electrodes arranged in the other direction, either the row direction or the column direction, may be electrically connected to each other, and a voltage may be selectively and simultaneously applied to the third electrodes arranged in the other direction by a second voltage controller that applies a voltage.

[0027] The above objects can be achieved by an inkjet printhead having a plurality of nozzles and ejecting a solution in an electro-hydraulic manner, the inkjet printhead comprising: a first electrode formed for each of the plurality of nozzles, the first electrode being applied with a voltage for ejecting the solution in an electro-hydraulic manner or being grounded; a first voltage controller applying a voltage to the first electrode; and a controller controlling the first electrode to be grounded or to receive a voltage from the first voltage controller, wherein when selectively ejecting the solution from the plurality of nozzles, the controller connects the first electrode of the nozzle from which the solution is ejected to the first voltage controller and applies a voltage, and grounds the first electrode of the nozzle adjacent to the nozzle from which the solution is ejected.

[0028] Here, when selectively ejecting the solution from among the plurality of nozzles, the control unit can connect the first electrode of the nozzle from which the solution is ejected to the first voltage controller to apply a voltage, and can ground the first electrodes of the remaining nozzles from which the solution is not ejected.

[0029] Here, the inkjet printhead may include a plurality of nozzle chambers in which ink supplied to each of the nozzles is stored, and a nozzle layer in which nozzle holes for ejecting the solution are formed at lower ends of the nozzle chambers, and the first electrode may be formed on an inner surface of the nozzle chamber.

[0030] Here, it is preferable that the distance between the first electrodes of adjacent nozzles is greater than the distance between the lower ends of the nozzles and the substrate to be printed. Effect of the Invention

[0031] According to the inkjet printhead of the present invention, droplets are ejected from a plurality of nozzles in an electro-hydraulic manner, and electric field interference between adjacent nozzles is minimized, thereby enabling easy control and uniform ejection of droplets.

[0032] Another advantage is that droplets can be ejected from each nozzle through individual control. [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is a diagram showing a schematic structure of a print head according to a first embodiment of the present invention. [Diagram 2] FIG. 13 is a diagram showing a schematic structure of a print head according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a diagram showing a schematic structure of a print head according to a third embodiment of the present invention. [Figure 4] FIG. 13 is a diagram showing a schematic structure of a print head according to a fourth embodiment of the present invention. [Diagram 5] FIG. 13 is a diagram showing a schematic structure of a print head according to a fifth embodiment of the present invention. [Figure 6] FIG. 13 is a diagram showing a schematic structure of a print head according to a sixth embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing a voltage application structure between the first electrode and the third electrode in FIG. [Figure 8] FIG. 8 is a diagram illustrating an example of the operation of FIG. 7. [Figure 9] FIG. 13 is a diagram showing a schematic structure of a print head according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Specific details of the embodiment are included in the detailed description and the drawings.

[0035] The advantages and features of the present invention, and the method of achieving the same, will become clear from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms, and the embodiments are provided merely to make the disclosure of the present invention complete and to fully inform those skilled in the art of the present invention of the scope of the invention, and the present invention is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

[0036] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings which illustrate an ink-jet printhead according to an embodiment of the present invention.

[0037] FIG. 1 is a diagram showing a schematic structure of a print head according to a first embodiment of the present invention.

[0038] The inkjet printhead according to the first embodiment of the present invention includes a plurality of nozzles 100, and each nozzle 100 can eject a solution by electrostatic force in an electro-hydrodynamic manner. In the drawings, two nozzles 100 are shown formed horizontally, one on the left and one on the right, but this is for the sake of explanation, and a greater number of nozzles 100 may be formed. In addition, a plurality of nozzles 100 may be arranged in the front and back directions of the paper, forming a plurality of nozzles 100 in a matrix shape.

[0039] The nozzles 100 may be formed in a nozzle layer 110. A plurality of nozzle chambers 112 for storing ink supplied from the outside are formed at intervals in the nozzle layer 110, and a nozzle hole 114 for ejecting a solution is formed at the lower end of the nozzle chamber 112. In this case, the nozzle chamber 112 may be formed in the shape of a truncated cone having an inclined surface formed on the inside so that the cross-sectional size becomes smaller toward the bottom as shown in the figure, but is not limited thereto and may be formed in a cylindrical shape.

[0040] For each nozzle 100, a lower end of the nozzle layer 110 may be protruded to form a protrusion 115, and a nozzle hole 114 may be formed at the lower end of the protrusion 115.

[0041] The first electrode 120 is disposed for each of the plurality of nozzles 100, and a voltage is applied to eject a solution in an electro-hydraulic manner. As shown in the figure, the first electrode 120 may be formed on the inner surface of the nozzle chamber 112. In the figure, the first electrode 120 is formed on the entire inner surface of the nozzle chamber 112, but it may also be formed partially on a part of the inner surface. Also, the upper end of the first electrode 120 may be partially extended onto the upper surface of the nozzle layer 110.

[0042] Although not shown, the first electrode 120 may be coated with an insulating layer. In the case where the first electrode 120 is coated with an insulating layer, when a voltage is applied to the first electrode 120, the solution flowing into the nozzle chamber 112 may be induced and charged by the induced voltage, and may be ejected to the outside through the nozzle hole 114 by the force of the electric field formed by the first electrode 120.

[0043] The first electrode 120 may be formed individually for each nozzle 100. Also, the first electrode 120 may be formed integrally for a plurality of nozzles 100. Furthermore, as will be described with reference to Figures 7 to 8, the first electrode 120 may be formed integrally for a plurality of nozzles 100 arranged in a row or column direction.

[0044] The first voltage controller 150 applies a voltage to the first electrode 120 to eject the solution in an electrohydraulic manner.

[0045] A ground electrode 200 may be formed under the substrate S, to which a voltage of a polarity opposite to that of the voltage applied to the first electrode 120 is applied or which is grounded. Furthermore, the ground electrode 200 may not be electrically connected. The ground electrode 200 may also be omitted. The ground electrode 200 forms a potential difference with the first electrode 120, so that an electric field for electro-hydraulic ejection is more uniformly formed between the nozzle 100 and the substrate S.

[0046] The second electrodes 130 are disposed at a distance between the first electrodes 120 formed in each nozzle 100 and are grounded. By disposing the second electrodes 130, which are grounded, between each nozzle 100, it is possible to minimize electric field interference between adjacent nozzles 100.

[0047] In this embodiment, the second electrodes 130 may be formed on the upper surface of the nozzle layer 110 between the nozzles 100 at positions spaced apart from the first electrodes 120 .

[0048] At this time, as shown in the enlarged view of FIG. 1, it is preferable that the distance B between the first electrode 120 and the second electrode 130 is greater than the distance A between the lower end of the nozzle 100 and the substrate S. In this case, since the electric field interference between the adjacent nozzles 100 can be minimized, the solution can be discharged by individual control for each nozzle 100. If the distance B between the first electrode 120 and the second electrode 130 is smaller than the distance A between the lower end of the nozzle 100 and the substrate S, the electric field generated in the first electrode 120 of any one nozzle 100 has a greater effect on the adjacent nozzle 100 than discharging droplets toward the target substrate, and it becomes difficult to control the solution to be discharged individually through each nozzle 100. Of course, for individual control, the first electrode 120 must be formed individually, not integrally, for the multiple nozzles 100. Here, the distance B between the first electrode 120 and the second electrode 130 may mean the minimum distance between the tips of the first electrode 120 and the second electrode 130.

[0049] Since the distance B between the first electrode 120 and the second electrode 130 is a fixed value at the time of manufacture, when using the inkjet print head of this embodiment, it is preferable to perform printing by controlling the distance A between the bottom end of the nozzle 100 and the substrate S to a value range smaller than B.

[0050] For reference, in Fig. 1, only one of the plurality of first electrodes 120 is connected to the first voltage controller 150, but in reality, all of the first electrodes 120 are connected to the first voltage controller 150. Also, in Fig. 1, only one second electrode 130 is shown to be grounded, but in reality, all of the second electrodes 130 are grounded. The same applies to the remaining figures described below.

[0051] FIG. 2 is a diagram showing a schematic structure of a print head according to a second embodiment of the present invention. In the following description, differences from the embodiment described above with reference to FIG. 1 will be mainly described.

[0052] In this embodiment, the shapes and structures of the nozzle layer 110 and the first electrode 120 are the same as those in the previously described embodiment.

[0053] In this embodiment, a groove 111 may be formed between each of the nozzles 100, the groove being dug downward on the upper side of the nozzle layer 110. The groove 111 may be formed to have a length longer than a width, but is not necessarily limited thereto.

[0054] In this case, the second electrode 130 to be grounded may be formed inside the groove 111. Also, after forming the second electrode 130 inside the groove 111, a blocking part 119 may be additionally formed to cover the groove 111 and block the second electrode 130 from being exposed to the outside of the groove 111. The blocking part 119 is preferably formed of an insulator.

[0055] In this structure, the second electrode 130, which is grounded, is formed inside the groove 111 covered with an insulator, so that electric field interference between adjacent nozzles 100 can be minimized.

[0056] FIG. 3 is a diagram showing a schematic structure of a print head according to a third embodiment of the present invention. In the following description, differences from the embodiment described above with reference to FIG. 1 will be mainly described.

[0057] In this embodiment, the shapes and structures of the nozzle layer 110 and the first electrode 120 are the same as those in the previously described embodiment.

[0058] In this embodiment, the second electrode 130 may be formed between each nozzle 100 on the lower surface of the nozzle layer 110. At this time, as described above, since the protrusion 115 is formed under the nozzle layer 110 for each nozzle 100, the second electrode 130 may be formed on the concave surface between the protrusions 115.

[0059] In this embodiment, the distance B between the lower end of the nozzle 100 and the second electrode 130 is preferably greater than the distance A between the lower end of the nozzle 100 and the substrate S. In this case, the electric field interference between the adjacent nozzles 100 can be minimized, so that each nozzle 100 can be individually controlled to eject the solution, and wetting does not occur. However, if the distance B between the lower end of the nozzle 100 and the second electrode 130 is smaller than the distance A between the lower end of the nozzle 100 and the substrate S, it is difficult to control the ejection of the solution individually through each nozzle 100, and wetting may occur. Here, the distance B between the lower end of the nozzle 100 and the second electrode 130 may mean the minimum distance between the tip of the second electrode 130 and the lower end of the nozzle 100.

[0060] In this embodiment, too, the distance B between the lower end of the nozzle 100 and the second electrode 130 is a fixed value at the time of manufacture, so when using the inkjet print head of this embodiment, it is preferable to perform printing by controlling the distance A between the lower end of the nozzle 100 and the substrate S to a value range smaller than B.

[0061] 2, a groove 111 may be formed on the lower surface of the nozzle layer 110, and the second electrode 130 may be formed inside the groove 111. Similarly, it is preferable to cover the groove 111 with a blocking portion 119, which is an insulator, so that the second electrode 130 is not exposed to the outside.

[0062] FIG. 4 is a schematic diagram showing the structure of a print head according to a fourth embodiment of the present invention. In the following description, the differences from the embodiment described above with reference to FIG. 1 will be mainly described.

[0063] In this embodiment, the shapes and structures of the nozzle layer 110 and the first electrode 120 are the same as those in the previously described embodiment. In this embodiment, a separation layer 140 may be further provided on the nozzle layer 110. The separation layer 140 is disposed on the nozzle layer 110, and a channel 142 connected to the nozzle chamber 112 is formed therethrough. The first electrode 120 is not formed inside the channel 142. The separation layer 140 may be formed of a wafer having a predetermined thickness. At this time, a second electrode 130 that is grounded may be formed on an upper surface of the isolation layer 140. The second electrode 130 may prevent electric field interference between adjacent nozzles 100.

[0064] Compared to the first embodiment, in this embodiment, the distance B between the first electrode 120 and the second electrode 130 can be maintained relatively far by the separation layer 140, so that the distance A between the bottom end of the nozzle 100 and the substrate S can be maintained even farther, allowing printing to be performed through individual control.

[0065] 2, a groove 111 may be formed on the upper surface of the isolation layer 140, and the second electrode 130 may be formed inside the groove 111. Similarly, it is preferable to cover the groove 111 with a blocking portion 119, which is an insulator, so that the second electrode 130 is not exposed to the outside.

[0066] FIG. 5 is a schematic diagram showing the structure of a print head according to a fifth embodiment of the present invention. In the following description, differences from the embodiment described above with reference to FIGS. 1 to 4 will be mainly described.

[0067] In this embodiment, the shapes and structures of the nozzle layer 110 and the first electrode 120 are the same as those of the previously described embodiment. Furthermore, it is the same as the embodiment previously described with reference to Fig. 4 in that a separation layer 140 is formed on the upper part of the nozzle layer 110 and a second electrode 130 is formed on the upper side of the separation layer 140. In this embodiment, unlike the embodiment previously described with reference to Fig. 4, a second electrode 130 that is grounded is also formed on the lower side of the nozzle layer 110, as in the embodiment of Fig. 3.

[0068] That is, in this embodiment, second electrodes 130b and 130a, which are grounded, are formed on the upper surface of the isolation layer 140 and the lower surface of the nozzle layer 110, respectively, to prevent electric field interference between adjacent nozzles 100.

[0069] 2, a groove may be formed in the upper surface of the isolation layer 140 so that the second electrode 130b is formed inside the groove, or a groove may be formed in the lower surface of the nozzle layer 110 so that the second electrode 130a is disposed inside the groove. Similarly, the grooves formed in the isolation layer 140 or the nozzle layer 110 are preferably covered with a blocking portion that is an insulator to prevent the second electrodes 130a, 130b from being exposed to the outside.

[0070] FIG. 6 is a diagram showing a schematic structure of a print head according to a sixth embodiment of the present invention, FIG. 7 is a diagram showing a voltage application structure between the first electrode 120 and the third electrode in FIG. 6, and FIG. 8 shows an example of the operation of FIG. 7.

[0071] In this embodiment, the nozzle layer 110 may be formed separately into a first nozzle layer 110_1 and a second nozzle layer 110_2.

[0072] The first nozzle layer 110_1 is located below the second nozzle layer 110_2 and has a plurality of nozzle chambers 112 in which ink is stored, and a nozzle hole 114 for ejecting a solution is formed at the lower end of each nozzle chamber 112. Also, a first electrode 120_1 may be formed on the inner surface of the nozzle chamber 112.

[0073] The second nozzle layer 110_2 is formed on the first nozzle layer 110_1, and a communication chamber 116 communicating with the nozzle chamber 112 of the first nozzle layer 110_1 is formed therethrough, and a third electrode 120_2 to which a voltage is applied to eject a solution in an electro-hydraulic manner is formed on an inner surface of the communication chamber 116. The first electrode 120_1 and the third electrode 120_2 are separate and not connected to each other, and the first electrode 120_1 may be connected to a first voltage controller 150_1 to apply a voltage thereto, and the third electrode 120_2 may be connected to a second voltage controller 150_2 to apply a voltage thereto.

[0074] The first electrode 120_1 and the third electrode 120_2 may all be electrodes that form an electric field between the nozzle 100 and the substrate S to eject the solution in an electrohydraulic manner.

[0075] In addition, the above-mentioned separation layer 140 may be formed on the upper portion of the second nozzle layer 110_2. The second electrode 130, which is grounded, may be formed on the upper surface of the separation layer 140, thereby preventing electric field interference between adjacent nozzles 100.

[0076] Although not shown, a second electrode 130 that is grounded and spaced apart from the first electrode 120_1 may be formed on an upper side of the first nozzle layer 110_1, as in FIG. 1. Also, a second electrode 130 that is grounded and spaced apart from the third electrode 120_2 may be formed on an upper side of the second nozzle layer 110_2. Also, although not shown, a second electrode 130 that is grounded may be formed on a lower side of the second nozzle layer 110_2, as in FIG. 3. Also, as described with reference to FIG. 2, a groove 111 may be formed in the first nozzle layer 110_1 and the second nozzle layer 110_2, and the second electrode 130 may be disposed inside the groove 111.

[0077] In this embodiment, the first electrode 120_1 and the third electrode 120_2 to which a voltage is applied are synchronized with each other to eject the solution in an electrohydraulic manner.

[0078] As described above, the inkjet printhead according to this embodiment may have a plurality of nozzles 100 arranged in a matrix in the row and column directions. Fig. 8 shows an example of a connection structure between the first electrodes 120_1 and the third electrodes 120_2 for the plurality of nozzles 100 arranged in a 3 row x 7 column format, but is not limited thereto.

[0079] At this time, the third electrodes 120_2 arranged in either the row direction or the column direction may be electrically connected in a straight line. In Fig. 7 and Fig. 8, seven third electrodes 120_2 in the row direction are electrically connected (indicated by a, b, c) and are connected to the second voltage controller 150_2 in three rows. Also, the first electrodes 120_1 arranged in either the row direction or the column direction may be electrically connected in a straight line. At this time, the first electrodes 120_1 and the third electrodes 120_2 are orthogonal to each other, and when the third electrodes 120_2 are connected in the row direction, the first electrodes 120_1 may be electrically connected in the column direction. In FIG. 7 and FIG. 8, three first electrodes 120_1 in a column direction are electrically connected to each other (indicated as 1, 2, 3, 4, 5, 6, and 7) and connected to the first voltage controller 150_1 in seven columns.

[0080] When the first electrodes 120_1 and the third electrodes 120_2 are individually connected to the first voltage controller 150_1 and the second voltage controller 150_2, respectively, the voltage connection structure (circuit) may become complicated. When the voltage connection structure becomes complicated, the distance between each nozzle 100 becomes large, and therefore it becomes impossible to arrange the nozzles 100 compactly. Furthermore, although a voltage is applied to the first electrodes 120_1 and the third electrodes 120_2, applying a voltage to each electrode individually may burden the capacity of the voltage controller 150. However, as in the present embodiment, by electrically connecting a plurality of electrodes arranged in a row direction or a column direction to the first electrodes 120_1 and the third electrodes 120_2, the voltage connection structure becomes simple and the capacity burden of the voltage controller 150 can be alleviated.

[0081] When droplets are to be ejected through some of the multiple nozzles 100, a voltage can be applied to a line connected to the first electrode 120_1 and the third electrode 120_2 corresponding to the nozzle 100 to eject the droplets.

[0082] 8, the b and 5 lines may be in an ON state, and the remaining a, c, 1, 2, 3, 4, 6, and 7 lines may be in an OFF state. In this case, the solution may be ejected only from the nozzle 100 at the intersection of the b and 5 lines. In this manner, the first electrode 120_1 and the third electrode 120_2 may be electrically connected in a straight line in the row or column direction, respectively, and a voltage may be selectively applied to each row or column, thereby selectively ejecting the solution from the nozzles 100.

[0083] FIG. 9 is a schematic diagram showing the structure of an ink-jet printer head according to a seventh embodiment of the present invention.

[0084] The inkjet printer head according to this embodiment may include a first electrode 120, a first voltage controller 150, and a control unit 160.

[0085] As in the previous embodiment, the inkjet printer head of this embodiment has a plurality of nozzles 100, each of which can eject a liquid by electrostatic force in an electrohydraulic manner.

[0086] The nozzles 100 may be formed in a nozzle layer 110. The configuration of the nozzle layer 110 is the same as that of the previous embodiment, and therefore will not be described.

[0087] The first electrode 120 is disposed for each of the plurality of nozzles 100, and a voltage is applied to the first electrode 120 to electro-hydraulically eject the solution. As in the previous embodiment, the first electrode 120 may be formed on the inner surface of the nozzle chamber 112 and may be coated with an insulating layer.

[0088] In this embodiment, the first electrode 120 can be applied with a voltage from the first voltage controller 150 or can be grounded.

[0089] The first voltage controller 150 applies a voltage to the first electrode 120 to eject the solution in an electrohydraulic manner.

[0090] The control unit 160 may control the first electrode 120 to be grounded or to receive a voltage from the first voltage controller 150. As shown in Fig. 9, the control unit 160 may control a switch formed between the first electrode 120 and the first voltage controller 150, and may control the first electrode 120 to be electrically connected to the first voltage controller 150 by the switch, or to be grounded.

[0091] In this embodiment, when a solution is selectively ejected from among the plurality of nozzles 100, the control unit 160 may control the first electrode 120 of the nozzle 100 ejecting the solution to be connected to the first voltage controller 150 so that a voltage is applied, and the first electrode 120 of the nozzle 100 adjacent to the nozzle 100 ejecting the solution and not ejecting the solution to be grounded. In Fig. 9, the control unit 160 connects the first electrode 120 of the left nozzle 100 to the first voltage controller 150 and grounds the first electrode 120 of the right nozzle 100, so that the solution is ejected only from the left nozzle 100 by the electro-hydraulic method.

[0092] In comparison with the previous embodiment, this embodiment does not have a grounded second electrode 130. Instead, in this embodiment, the first electrode 120 of a nozzle 100 that does not eject a solution adjacent to a nozzle 100 that ejects a solution is grounded, thereby minimizing electric field interference between the nozzles 100 that eject a solution.

[0093] At this time, the control unit 160 may control the first electrodes 120 of not only the nozzles 100 adjacent to the nozzle 100 from which the solution is ejected, but also all the remaining nozzles 100 from which the solution is not ejected to be grounded.

[0094] 9, it is preferable that the distance B between the first electrodes 120 of adjacent nozzles 100 is greater than the distance A between the lower end of the nozzle 100 and the substrate S. In this case, since the electric field interference between the adjacent nozzles 100 can be minimized, the solution can be ejected by individual control for each nozzle 100.

[0095] Since the distance B between the first electrodes 120 of adjacent nozzles 100 is a fixed value at the time of manufacture, when using the inkjet print head of this embodiment, it is preferable to perform printing by controlling the distance A between the bottom end of the nozzle 100 and the substrate S to a value range smaller than B.

[0096] The scope of the present invention is not limited to the above-mentioned embodiment, but may be embodied in various forms within the scope of the appended claims. Any person having ordinary skill in the art to which the invention pertains may make various modifications without departing from the gist of the present invention as claimed in the claims. [Explanation of symbols]

[0097] 100 nozzles 110 Nozzle Layer 111 Groove 112 Nozzle Chamber 114 Nozzle hole 115 Protrusion 116 Connecting chamber 119 Circuit Breaker 120 1st electrode 130 2nd electrode 140 Separation layer 150 First voltage controller 160 Control section 200 ground electrode

Claims

1. In an inkjet printhead having a plurality of nozzles and discharging a solution by an electrohydraulic method, a first electrode formed for each of the plurality of nozzles, to which a voltage is applied to eject the solution in an electrohydraulic manner; a first voltage controller for applying a voltage to the first electrode; a second electrode that is spaced apart between the first electrodes formed in each of the nozzles and grounded to prevent electric field interference between the nozzles; a plurality of nozzle chambers in which ink is stored for each of the nozzles; a nozzle layer having a nozzle hole formed at a lower end of the nozzle chamber for ejecting the solution; the first electrodes are formed on an inner surface of the nozzle chamber, and the second electrodes are individually formed between adjacent first electrodes.

2. The inkjet print head as described in claim 1, characterized in that the second electrode is formed on an upper surface of the nozzle layer.

3. The inkjet printhead of claim 2 , wherein a distance between the first electrode and the second electrode is greater than a distance between a bottom end of the nozzle and a substrate.

4. 2. The ink-jet printhead of claim 1, wherein a groove is formed in an upper surface of the nozzle layer, the second electrode being formed within the groove.

5. The ink-jet printhead of claim 4, further comprising a blocking portion made of an insulating material and covering the groove to block exposure of the second electrode to the outside of the groove.

6. The inkjet printhead of claim 1, wherein the second electrode is formed on an underside of the nozzle layer.

7. 7. The ink-jet printhead of claim 6, wherein a protrusion is formed at a lower end of the nozzle layer for each of the nozzles, the protrusion having the nozzle hole at a lower end thereof, and the second electrode is formed in a concave surface between the protrusions.

8. The ink-jet printhead of claim 6 , wherein a distance between a bottom end of the nozzle and the second electrode is greater than a distance between a bottom end of the nozzle and a substrate.

9. The inkjet printhead described in claim 1, characterized in that a groove is formed on the lower surface of the nozzle layer such that the second electrode is formed inside the groove.

10. The ink-jet printhead of claim 9, further comprising a blocking portion made of an insulating material and covering the groove to block exposure of the second electrode to the outside of the groove.

11. The inkjet print head comprises: a separation layer disposed on the nozzle layer and having a channel formed therethrough and connected to the nozzle chamber, 2. The ink-jet printhead of claim 1, wherein the second electrode is formed on an upper surface of the separation layer.

12. The ink-jet printhead of claim 11, wherein the second electrode is also formed on a lower surface of the nozzle layer.

13. The inkjet print head comprises: a separation layer disposed on the nozzle layer and having a channel formed therethrough and connected to the nozzle chamber, 2. The ink-jet printhead of claim 1, wherein a groove is formed in an upper surface of the isolation layer, the second electrode being formed within the groove.

14. The ink-jet printhead of claim 13, further comprising a blocking portion made of an insulating material and covering the groove to block exposure of the second electrode to the outside of the groove.

15. The nozzle layer comprises: a first nozzle layer in which a plurality of nozzle chambers in which the ink supplied to each of the nozzles is stored and the nozzle holes for ejecting the solution are formed at lower ends of the nozzle chambers, and the first electrodes are formed on inner surfaces of the nozzle chambers; 14. The ink-jet printhead of claim 2, further comprising: a second nozzle layer formed on the first nozzle layer, the second nozzle layer having a plurality of communication chambers communicating with the nozzle chambers, and a third electrode formed on an inner surface of the communication chambers to which a voltage is applied for ejecting the solution in an electro-hydraulic manner.

16. The nozzles are arranged in a matrix, and the first electrodes arranged in one direction, either a row direction or a column direction, are electrically connected to each other, and a voltage is selectively applied simultaneously to the first electrodes arranged in one direction by the first voltage controller; 16. The ink-jet printhead of claim 15, wherein the third electrodes arranged in the other direction of the row direction or the column direction are electrically connected to each other, and a voltage is selectively applied to the third electrodes arranged in the other direction simultaneously by a second voltage controller that applies a voltage.

17. In an inkjet printhead having a plurality of nozzles and discharging a solution by an electrohydraulic method, a first electrode formed for each of the plurality of nozzles, the first electrode being grounded or having a voltage applied thereto for electro-hydraulically discharging the solution; a first voltage controller for applying a voltage to the first electrode; a control unit that controls the first electrode to be grounded or to apply a voltage from the first voltage controller; and when selectively ejecting the solution from among the plurality of nozzles, the control unit connects the first electrode of the nozzle from which the solution is ejected to the first voltage controller to apply a voltage thereto, and grounds the first electrode of the nozzle from which the solution is not ejected and adjacent to the nozzle from which the solution is ejected.

18. When the solution is selectively ejected from the plurality of nozzles, the control unit applies a voltage to the first electrode of the nozzle from which the solution is ejected by connecting the first electrode to the first voltage controller; 20. The ink-jet printhead of claim 17, wherein the first electrode of the nozzle from which the remaining solution is not ejected is grounded.

19. The inkjet print head comprises: a plurality of nozzle chambers in which ink is stored for each of the nozzles; a nozzle layer having a nozzle hole formed at a lower end of the nozzle chamber for ejecting the solution; 20. The ink-jet printhead of claim 17, wherein the first electrode is formed on an inner surface of the nozzle chamber.

20. The ink-jet printhead of claim 19, wherein a distance between the first electrodes of adjacent nozzles is greater than a distance between a bottom end of the nozzle and a substrate.

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