Inkjet printhead

Abstract

The present invention relates to an inkjet printhead having a plurality of nozzles and ejecting a solution via electrohydrodynamics, comprising: a first electrode formed for each of the plurality of nozzles and subjected to a voltage for ejecting the solution via electrohydrodynamics; a first voltage controller for applying a voltage to the first electrode; and a second electrode spaced apart from the first electrode formed on each nozzle and grounded, for preventing electric field interference between the nozzles.

Description

Technical Field

[0001] The present invention relates to an inkjet printing head, and more particularly to an inkjet printing head having multiple nozzles and spraying a solution through an electrohydrodynamic method. Prior Art

[0002] Generally speaking, an inkjet printhead is a device that sprays tiny droplets of ink onto desired locations on a print medium, thereby printing an image of a specified color on the surface of the print medium. Recently, the application of inkjet printheads has expanded to include flat-panel displays such as liquid crystal displays (LCDs) and organic light-emitting devices (OLEDs), flexible displays such as electronic paper (E-paper), printed electronics such as metal wiring, and the biotechnology field.

[0003] Among drop-on-demand (DOD) inkjet print heads, two types are known, depending on the ejection method: a piezoelectric inkjet print head that ejects ink using pressure waves generated by the deformation of a piezoelectric body, and an electrohydrodynamic inkjet print head that ejects ink using electrostatic force.

[0004] Piezoelectric inkjet printheads use a piezoelectric element to vibrate a membrane, thereby applying pressure to the ink chamber to eject ink. Generally speaking, droplets are ejected when pressure is applied just enough to overcome the surface tension and viscosity of the ink on the nozzle surface. Furthermore, the applied pressure must be high enough to accelerate the ejected droplets at a speed that allows them to land accurately on the print medium. In piezoelectric inkjet printheads, achieving droplets smaller than a few picoliters requires reducing the deformation energy within the pressure chamber. However, this also reduces the ejection energy per unit volume of the ejected droplets, resulting in a lower droplet ejection velocity. This reduction in droplet ejection velocity can lead to problems with accurately projecting droplets to the desired location.

[0005] Piezoelectric inkjet print heads offer the following advantages: easy control of the printing process, and because ejection energy is provided through the mechanical deformation of the piezoelectric element, the inks used are not restricted. However, piezoelectric inkjet print heads have limitations: they struggle to produce ultrafine droplets smaller than a few picoliters, typically only capable of ejecting inks with viscosities of 10 cPs, and are unable to eject high-viscosity inks. Furthermore, due to limited ejection energy, larger droplets larger than 80 picoliters are difficult to eject. In particular, for applications in printed electronics processes such as displays, unlike conventional pattern printing, volume uniformity of ejected droplets across multiple nozzles is crucial. Despite these limitations, piezoelectric inkjet print heads have their limitations.

[0006] Electrohydrodynamic inkjet printheads generate ejection energy by applying electrostatic force to the ink surface formed at the nozzle tip. This allows for the production of ultrafine droplets ranging from a few picoliters to femtoliters, and even high-viscosity ink droplets of 1,000 cPs. They are also capable of producing larger droplets exceeding 80 picoliters. Because control is achieved through the distribution of the electric field formed on the nozzle, the drive system is relatively simple, and the ejected ink droplets exhibit excellent directionality, facilitating precision printing.

[0007] However, when multiple nozzles are formed on an electrohydrodynamic inkjet print head, electric field interference occurs between adjacent nozzles, resulting in uneven sizes of droplets ejected through the multiple nozzles, which leads to a problem of reduced printing quality.

[0008] [Prior Art Literature]

[0009] Patent document: Korean Patent No. 1310759. Summary of the Invention

[0010] The present invention is proposed to solve the conventional problems described above. Its purpose is to provide an inkjet print head having multiple nozzles and ejecting droplets using an electrohydrodynamic method. The inkjet print head is provided with a grounded second electrode spaced between first electrodes formed on each nozzle and ejecting droplets using an electrohydrodynamic method, thereby preventing electric field interference between the nozzles.

[0011] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above. For other technical problems not mentioned, technicians in the technical field to which the present invention belongs should be able to clearly understand them based on the following description.

[0012] The above-mentioned object can be achieved by the inkjet printing head of the present invention, which has multiple nozzles and ejects solution through electrohydrodynamics, and includes: a first electrode formed for each of the multiple nozzles and applied with a voltage for ejecting solution through electrohydrodynamics; a first voltage controller for applying voltage to the first electrode; and a second electrode spaced apart and grounded between the first electrodes formed on each nozzle, and used to prevent electric field interference between the nozzles.

[0013] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle hole for ejecting a solution formed at the lower end of the nozzle chamber, the first electrode being formed on the inner side of the nozzle chamber, and the second electrode being formed on the upper side of the nozzle layer.

[0014] Here, it is preferred 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 printed object.

[0015] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle hole for ejecting a solution formed at the lower end of the nozzle chamber, a downwardly recessed groove formed on the upper side of the nozzle layer, and the second electrode formed inside the groove.

[0016] Here, the method may further include: a blocking portion formed of an insulator and covering the groove, thereby blocking the second electrode from being exposed to the outside of the groove.

[0017] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle hole for ejecting a solution formed at the lower end of the nozzle chamber, the first electrode being formed on the inner side of the nozzle chamber, and the second electrode being formed on the lower side of the nozzle layer.

[0018] Here, for each nozzle, a protrusion may be formed at the lower end of the nozzle layer and the nozzle hole may be formed at the lower end of the protrusion, and the second electrode may be formed on the concave surface between the protrusions.

[0019] Here, it is preferred that the distance between the lower end of the nozzle and the second electrode is greater than the distance between the lower end of the nozzle and the printed object.

[0020] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle hole for ejecting a solution formed at the lower end of the nozzle chamber, an upwardly concave groove formed on the lower side of the nozzle layer, and the second electrode formed inside the groove.

[0021] Here, the method may further include: a blocking portion formed of an insulator and covering the groove, thereby blocking the second electrode from being exposed to the outside of the groove.

[0022] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and having nozzle holes for ejecting a solution formed at the lower ends of the nozzle chambers; and a partition layer, arranged above the nozzle layer and having a flow channel connected to the nozzle chambers formed therethrough, the first electrode being formed on the inner side surface of the nozzle chamber, and the second electrode being formed on the upper side surface of the partition layer.

[0023] Here, the second electrode may be further formed on the lower side of the nozzle layer.

[0024] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and having nozzle holes formed at the lower ends of the nozzle chambers for ejecting a solution; and a partition layer, arranged above the nozzle layer and having a flow channel formed therethrough connected to the nozzle chambers, a downwardly recessed groove formed on the upper side of the partition layer, and the second electrode formed within the groove.

[0025] Here, the method may further include: a blocking portion formed of an insulator and covering the groove, thereby blocking the second electrode from being exposed to the outside of the groove.

[0026] Here, the nozzle layer may include: a first nozzle layer, which is formed with a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle hole for spraying a solution is formed at the lower end of the nozzle chamber, and the first electrode is formed on the inner side surface of the nozzle chamber; and a second nozzle layer, which is formed above the first nozzle layer, is formed with a plurality of connecting chambers connected to the nozzle chamber, and a third electrode is formed on the inner side surface of the connecting chamber, and the third electrode is applied with a voltage for spraying the solution through an electrohydrodynamic method.

[0027] Here, multiple nozzles can be arranged in a matrix form, and the first electrodes arranged along a certain direction in the column direction or the row direction are electrically connected to each other, so that through the first voltage controller, the first electrodes arranged along one direction are selectively and simultaneously applied with voltage, and the third electrodes arranged along the other direction in the column direction or the row direction are electrically connected to each other, so that through the second voltage controller for applying voltage, the third electrodes arranged along the other direction are selectively and simultaneously applied with voltage.

[0028] In addition, the above-mentioned purpose can be achieved through the inkjet print head of the present invention, which has multiple nozzles and sprays solution through electrohydrodynamics, wherein it includes: a first electrode, formed for each of the multiple nozzles, and applied with a voltage for spraying solution through electrohydrodynamics or grounded; a first voltage controller, used to apply voltage to the first electrode; and a control unit, used to control the first electrode to be grounded or to apply voltage to the first electrode by the first voltage controller, when the multiple nozzles are selectively sprayed with solution, the control unit connects the first electrode of the nozzle to be sprayed with the solution to the first voltage controller so that the first electrode is applied with voltage, and grounds the first electrode of the nozzle adjacent to the nozzle to be sprayed with solution that does not spray solution.

[0029] Here, when multiple nozzles are selectively sprayed with solution, the control unit can connect the first electrode of the nozzle to be sprayed with solution to the first voltage controller so that voltage is applied to the first electrode, and ground the first electrodes of the remaining nozzles that are not spraying solution.

[0030] Here, the inkjet print head may include: a nozzle layer, having a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle hole for ejecting a solution formed at the lower end of the nozzle chamber, and the first electrode may be formed on the inner side surface of the nozzle chamber.

[0031] Here, the distance between the first electrodes of adjacent nozzles may be greater than the distance between the lower end of the nozzle and the printed object.

[0032] According to the inkjet print head of the present invention as described above, droplets are ejected using multiple nozzles through electrohydrodynamics, which has the advantages of being able to minimize electric field interference between adjacent nozzles, thereby being easy to control and being able to eject droplets uniformly.

[0033] In addition, it has the advantage of being able to independently control each nozzle to spray droplets. Simple diagram description

[0034] FIG. 1 is a diagram showing a schematic structure of a printing head according to a first embodiment of the present invention. FIG. 2 is a diagram showing a schematic structure of a printing head according to a second embodiment of the present invention. FIG3 is a diagram showing a schematic structure of a printing head according to a third embodiment of the present invention. FIG. 4 is a diagram showing a schematic structure of a printing head according to a fourth embodiment of the present invention. FIG5 is a diagram showing a schematic structure of a printing head according to a fifth embodiment of the present invention. FIG6 is a diagram showing a schematic structure of a printing head according to a sixth embodiment of the present invention. FIG. 7 is a diagram showing a voltage application structure of the first electrode and the third electrode in FIG. 6 . FIG8 shows an example of the operation of FIG7. FIG. 9 is a diagram showing a schematic structure of a printing head according to a seventh embodiment of the present invention. Implementation Method

[0035] The detailed description and drawings include details of the embodiments.

[0036] The advantages and features of the present invention, as well as the methods for achieving these advantages and features, will be clearly understood with reference to the drawings and the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below and can be implemented in a variety of different forms. These embodiments are provided solely to fully disclose the present invention and to fully inform those skilled in the art of the present invention of the scope of the invention. The present invention is to be defined by the scope of the claims. Throughout this specification, the same symbols represent the same structural elements.

[0037] Hereinafter, the present invention will be described in detail through embodiments of the present invention with reference to drawings for illustrating an inkjet print head.

[0038] FIG. 1 is a diagram showing a schematic structure of a printing head according to a first embodiment of the present invention.

[0039] The inkjet print head according to the first embodiment of the present invention has multiple nozzles 100, each of which can eject a solution using electrostatic force via electrohydrodynamics. While the figure shows two nozzles 100 arranged horizontally on the left and right sides, this is for illustrative purposes only; a greater number of nozzles 100 may be provided. Furthermore, multiple nozzles 100 may also be arranged in the front-to-back direction of the paper, forming a matrix.

[0040] Multiple nozzles 100 can be formed on a nozzle layer 110. Multiple nozzle chambers 112 for storing externally supplied ink are spaced apart and formed on the nozzle layer 110. Nozzle holes 114 for ejecting the solution are formed at the lower ends of the nozzle chambers 112. As shown in the figure, the nozzle chambers 112 can be formed in the shape of a truncated cone with an inclined surface formed inside so that the cross-section decreases toward the bottom. However, this is not limiting and the nozzle chambers 112 can also be formed in a cylindrical shape.

[0041] For each nozzle 100 , a protrusion 115 may be formed protruding from a lower end portion of the nozzle layer 110 , and the nozzle hole 114 may be formed at a lower end of the protrusion 115 .

[0042] Each of the multiple nozzles 100 is configured with a first electrode 120, to which a voltage is applied for ejecting a solution using an electrohydrodynamic method. As shown in the figure, the first electrode 120 can be formed on the inner side surface of the nozzle chamber 112. Although the first electrode 120 is formed on the entire inner side surface of the nozzle chamber 112 in the figure, it can also be formed partially on a portion of the inner side surface of the nozzle chamber 112. Furthermore, the upper end of the first electrode 120 can also be formed to partially extend onto the upper surface of the nozzle layer 110.

[0043] Although not shown, the first electrode 120 may also be 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 charged by the induced voltage. The solution can then be ejected through the nozzle orifice 114 to the outside using the force of the electric field generated by the first electrode 120.

[0044] The first electrode 120 can be formed independently for each nozzle 100. Alternatively, the first electrode 120 can be formed integrally for multiple nozzles 100. Furthermore, as described with reference to FIG7 and FIG8 , the first electrode 120 can also be formed integrally for multiple nozzles 100 arranged in a row or column direction.

[0045] The first voltage controller 150 applies a voltage to the first electrode 120 for ejecting the solution through the electrohydrodynamic method.

[0046] A ground electrode 200 may be provided below the printed material S, to which a voltage of opposite polarity to that applied to the first electrode 120 or to which ground is applied. Furthermore, the ground electrode 200 may not be electrically connected. Furthermore, the ground electrode 200 may be omitted. The ground electrode 200 creates a potential difference with the first electrode 120, thereby more uniformly forming the electric field between the nozzle 100 and the printed material S for ejection using the electrohydrodynamic method.

[0047] The second electrode 130 is spaced apart and grounded between the first electrodes 120 formed in each nozzle 100. Since the grounded second electrode 130 is arranged between each nozzle 100, electric field interference between adjacent nozzles 100 can be minimized.

[0048] At this time, in this embodiment, the second electrode 130 may be formed on the upper side of the nozzle layer 110 at a position between the nozzles 100 and spaced apart from the first electrode 120 .

[0049] At this point, as shown in the enlarged view of Figure 1, the distance B between the first electrode 120 and the second electrode 130 is preferably greater than the distance A between the lower end of the nozzle 100 and the printed object S. This minimizes electric field interference between adjacent nozzles 100, allowing each nozzle 100 to be independently controlled to eject the solution. When the distance B between the first electrode 120 and the second electrode 130 is less than the distance A between the lower end of the nozzle 100 and the printed object S, the electric field generated by the first electrode 120 of one nozzle 100 has a greater impact on the adjacent nozzle 100 than on the droplet ejection toward the target substrate, making it difficult to control the independent ejection of the solution through each nozzle 100. Of course, to ensure independent control, the first electrode 120 of multiple nozzles 100 should not be formed as a single unit, but should be formed independently. Here, the distance B between the first electrode 120 and the second electrode 130 can refer to the minimum distance between the ends of the first electrode 120 and the second electrode 130.

[0050] The distance B between the first electrode 120 and the second electrode 130 is a fixed value during manufacturing. Therefore, when using the inkjet print head of this embodiment, it is preferred to control the distance A between the lower end of the nozzle 100 and the printed object S within a range less than the value of B for printing.

[0051] Please also note that although FIG1 shows only one of the plurality of first electrodes 120 connected to the first voltage controller 150, in reality, all first electrodes 120 are connected to the first voltage controller 150. Furthermore, although FIG1 shows only one second electrode 130 grounded, in reality, all second electrodes 130 are grounded. This applies similarly to the remaining figures described below.

[0052] FIG. 2 is a diagram showing a schematic structure of a printing head according to a second embodiment of the present invention.

[0053] In the following description, the differences from the embodiment described above with reference to FIG. 1 are mainly described.

[0054] In this embodiment, the shape and structure of the nozzle layer 110 and the first electrode 120 are the same as those in the previous embodiment.

[0055] In this embodiment, a downwardly recessed groove 111 may be formed between each nozzle 100 on the upper side of the nozzle layer 110. The groove 111 may be formed in a shape where the length is greater than the width, but is not necessarily limited to this.

[0056] In this case, the grounded second electrode 130 can be formed inside the groove 111. Furthermore, after the second electrode 130 is formed inside the groove 111, a blocking portion 119 can be further formed. The blocking portion 119 covers the groove 111 to block the second electrode 130 from being exposed outside the groove 111. Preferably, the blocking portion 119 is formed of an insulator.

[0057] As the grounded second electrode 130 is formed in this structure inside the groove 111 covered by the insulator, electric field interference between adjacent nozzles 100 can be minimized.

[0058] FIG3 is a diagram showing a schematic structure of a printing head according to a third embodiment of the present invention.

[0059] In the following description, the differences from the embodiment described above with reference to FIG. 1 are mainly described.

[0060] In this embodiment, the shape and structure of the nozzle layer 110 and the first electrode 120 are the same as those in the previous embodiment.

[0061] In this embodiment, the second electrode 130 can be formed between each nozzle 100 on the lower side of the nozzle layer 110. Since each nozzle 100 has a protrusion 115 formed below the nozzle layer 110 as described above, the second electrode 130 can be formed on the concave surface between the protrusions 115.

[0062] 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 printed substrate S. This minimizes electric field interference between adjacent nozzles 100, allowing each nozzle 100 to be independently controlled to eject the solution without causing wetting. However, if the distance B between the lower end of the nozzle 100 and the second electrode 130 is less than the distance A between the lower end of the nozzle 100 and the printed substrate S, it becomes difficult to control the independent ejection of the solution 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 refers to the minimum distance between the end of the second electrode 130 and the lower end of the nozzle 100.

[0063] In this embodiment, the distance B between the lower end of the nozzle 100 and the second electrode 130 is a fixed value during manufacturing. Therefore, when using the inkjet print head of this embodiment, it is preferred to control the distance A between the lower end of the nozzle 100 and the printed object S within a range less than the value of B for printing.

[0064] Although not shown, as described with reference to FIG. 2 , an upwardly recessed groove 111 may be formed on the lower side of the nozzle layer 110, and a second electrode 130 may be formed within the groove 111. Similarly, the groove 111 is preferably covered with a blocking portion 119 serving as an insulator to prevent the second electrode 130 from being exposed to the outside.

[0065] FIG. 4 is a diagram showing a schematic structure of a printing head according to a fourth embodiment of the present invention.

[0066] In the following description, the differences from the embodiment described above with reference to FIG. 1 are also mainly described.

[0067] In this embodiment, the shape and structure of the nozzle layer 110 and the first electrode 120 are the same as those in the previous embodiment.

[0068] In this embodiment, a spacer layer 140 may be further included above the nozzle layer 110. The spacer layer 140 is disposed above the nozzle layer 110 and has a flow channel 142 formed therethrough, connecting to the nozzle chamber 112. The first electrode 120 is not formed within the flow channel 142. The spacer layer 140 may be formed from a wafer of a predetermined thickness.

[0069] At this time, a grounded second electrode 130 may be formed on the upper side of the partition layer 140. The second electrode 130 can prevent electric field interference between adjacent nozzles 100.

[0070] Compared to the first embodiment, in this embodiment, the distance B between the first electrode 120 and the second electrode 130 can be kept relatively far apart through the spacer 140. Therefore, the distance A between the lower end of the nozzle 100 and the printed object S can be kept farther, and printing can be performed through independent control.

[0071] Although not shown, as described with reference to FIG2 , a downwardly recessed groove 111 may be formed on the upper side of the spacer 140, and the second electrode 130 may be formed within the groove 111. Similarly, the groove 111 is preferably covered by a blocking portion 119 serving as an insulator to prevent the second electrode 130 from being exposed to the outside.

[0072] FIG5 is a diagram showing a schematic structure of a printing head according to a fifth embodiment of the present invention.

[0073] In the following description, the differences from the embodiment described above with reference to FIG. 1 to FIG. 4 are also mainly described.

[0074] In this embodiment, the shape and structure of the nozzle layer 110 and first electrode 120 are the same as those in the previous embodiment. Furthermore, the formation of a spacer layer 140 above the nozzle layer 110 and the formation of a second electrode 130 on the upper side of the spacer layer 140 are similar to the embodiment described previously with reference to FIG4 . In contrast to the embodiment described previously with reference to FIG4 , this embodiment also includes a grounded second electrode 130 formed on the lower side of the nozzle layer 110, similar to the embodiment shown in FIG3 .

[0075] That is, in this embodiment, grounded second electrodes 130 b and 130 a are formed on the upper side of the partition layer 140 and the lower side of the nozzle layer 110 , respectively, so as to prevent electric field interference between adjacent nozzles 100 .

[0076] Although not shown, as described with reference to FIG2 , a downwardly recessed groove 111 may be formed on the upper side of the spacer layer 140, with the second electrode 130b formed within the groove 111, or an upwardly recessed groove may be formed on the lower side of the nozzle layer 110, with the second electrode 130a disposed within the groove. Similarly, the groove 111 formed in the spacer layer 140 or the nozzle layer 110 is preferably covered by a blocking portion 119, which serves as an insulator, to prevent the second electrodes 130a and 130b from being exposed to the outside.

[0077] 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 of the first electrode 120 a and the third electrode 120 b in FIG. 6 , and FIG. 8 shows an example of the operation of FIG. 7 .

[0078] In this embodiment, the nozzle layer 110 may be formed separately from a first nozzle layer 110a and a second nozzle layer 110b.

[0079] The first nozzle layer 110a is located below the second nozzle layer 110b and is formed with a plurality of nozzle chambers 112 for storing ink. A nozzle hole 114 for ejecting solution is formed at the lower end of each nozzle chamber 112. Furthermore, a first electrode 120a may be formed on the inner side of each nozzle chamber 112.

[0080] The second nozzle layer 110b is formed above the first nozzle layer 110a and has a connecting chamber 116 formed therethrough, communicating with the nozzle chamber 112 of the first nozzle layer 110a. A third electrode 120b, to which a voltage is applied for ejecting a solution using an electrohydrodynamic method, is formed on the inner side of the connecting chamber 116. The first electrode 120a and the third electrode 120b are separated and disconnected from each other. The first electrode 120a is connected to a first voltage controller 150a and has a voltage applied thereto, while the third electrode 120b is connected to a second voltage controller 150b and has a voltage applied thereto.

[0081] The first electrode 120 a and the third electrode 120 b may both be electrodes for forming an electric field between the nozzle 100 and the object to be printed S in order to eject the solution through an electrohydrodynamic method.

[0082] In addition, the aforementioned partition layer 140 may be formed above the second nozzle layer 110b. A grounded second electrode 130 may be formed on the upper side of the partition layer 140 to prevent electric field interference between adjacent nozzles 100.

[0083] Although not shown, a second electrode 130 spaced apart from the first electrode 120a and grounded may be formed on the upper side of the first nozzle layer 110a, as shown in FIG1 . Furthermore, a second electrode 130 spaced apart from the third electrode 120b and grounded may also be formed on the upper side of the second nozzle layer 110b. Furthermore, although not shown, a grounded second electrode 130 may be formed on the lower side of the second nozzle layer 110b, as shown in FIG3 . Furthermore, as described with reference to FIG2 , grooves 111 may be formed in the first nozzle layer 110a and the second nozzle layer 110b, and the second electrode 130 may be disposed within the grooves 111.

[0084] In this embodiment, the first electrode 120a and the third electrode 120b to which voltage is applied can be synchronized and spray the solution through an electrohydrodynamic method.

[0085] As previously described, the inkjet print head according to this embodiment may have multiple nozzles 100 arranged in a matrix along the column and row directions. FIG8 schematically illustrates the connection structure between the first electrode 120a and the third electrode 120b of multiple nozzles 100 arranged in three columns and seven rows, but the present invention is not limited thereto.

[0086] In this case, multiple third electrodes 120b arranged along either the column or row direction can be electrically connected in a straight line. Figures 7 and 8 show seven third electrodes 120b in the column direction electrically connected (indicated by a, b, and c) and electrically connected to the second voltage controller 150b in three columns. Furthermore, for the first electrodes 120a, multiple first electrodes 120a arranged along either the column or row direction can also be electrically connected in a straight line. In this case, the electrical connection directions of the first and third electrodes 120a, 120b, can be orthogonal to each other. That is, while the third electrodes 120b are electrically connected along the column direction, the first electrodes 120a can be electrically connected along the row direction. In Figures 7 and 8, the three first electrodes 120a in the row direction are electrically connected (indicated by 1, 2, 3, 4, 5, 6, and 7) and connected to the first voltage controller 150a in seven rows.

[0087] If multiple first electrodes 120a and third electrodes 120b are independently connected to the first voltage controller 150a and the second voltage controller 150b, respectively, the voltage connection structure (circuit) may become complex. A complex voltage connection structure increases the distance between nozzles 100, making it impossible to compactly arrange multiple nozzles 100. Furthermore, if voltages are applied to the first electrodes 120a and the third electrodes 120b independently, this may place a capacity burden on the first voltage controller 150. However, by electrically connecting multiple first electrodes 120a and third electrodes 120b arranged along the column or row direction, as in this embodiment, the voltage connection structure can be simplified and the capacity burden on the first voltage controller 150 can be reduced.

[0088] When ejecting droplets through a portion of the plurality of nozzles 100 , a voltage may be applied to lines connected to the first electrode 120 a and the third electrode 120 b corresponding to the respective nozzles 100 to eject the droplets.

[0089] For example, in Figure 8 , lines b and 5 can be connected, while lines a, c, 1, 2, 3, 4, 6, and 7 can be disconnected. In this case, only the nozzles 100 at the intersection of lines b and 5 can spray solution. In this manner, by electrically connecting the first electrode 120a and the third electrode 120b in a straight line in the column or row direction, and selectively applying voltage to each column or row, multiple nozzles 100 can selectively spray solution.

[0090] FIG. 9 is a diagram showing a schematic structure of an inkjet print head according to a seventh embodiment of the present invention.

[0091] The inkjet print head of this embodiment may be configured to include a first electrode 120 , a first voltage controller 150 , and a control portion 160 .

[0092] Similar to the above-mentioned embodiment, the inkjet print head of this embodiment has a plurality of nozzles 100, and each nozzle 100 can eject a solution by utilizing electrostatic force through electrohydrodynamics.

[0093] A plurality of nozzles 100 may be formed on a nozzle layer 110. The structure of the nozzle layer 110 is the same as that of the previous embodiment, and thus description thereof is omitted.

[0094] A first electrode 120 is provided for each of the plurality of nozzles 100 and is applied with a voltage for ejecting the solution using an electrohydrodynamic method. Similar to the previous embodiment, the first electrode 120 can be formed on the inner side of the nozzle chamber 112 and can be coated with an insulating layer.

[0095] In this embodiment, the first electrode 120 may be applied with a voltage or grounded by the first voltage controller 150 .

[0096] The first voltage controller 150 applies a voltage to the first electrode 120 for ejecting the solution through the electrohydrodynamic method.

[0097] The control unit 160 can control the first electrode 120 to be grounded, or control the first voltage controller 150 to apply a voltage to the first electrode 120. As shown in FIG9 , the control unit 160 can control a switch formed between the first electrode 120 and the first voltage controller 150 to electrically connect the first electrode 120 and the first voltage controller 150 through the switch, or control the first electrode 120 to be grounded.

[0098] In this embodiment, when multiple nozzles 100 are selectively spraying solution, the control unit 160 controls the first electrode 120 of the nozzle 100 spraying the solution to be connected to the first voltage controller 150 so that a voltage is applied to the first electrode 120, and controls the first electrodes 120 of the nozzles 100 adjacent to the nozzle 100 spraying the solution but not spraying the solution to be grounded. In FIG9 , 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, thereby allowing only the left nozzle 100 to spray the solution using electrohydrodynamics.

[0099] Compared to the previous embodiment, this embodiment does not include a grounded second electrode 130. Instead, in this embodiment, the first electrode 120 of the nozzle 100 not spraying the solution, which is adjacent to the nozzle 100 spraying the solution, is grounded, thereby minimizing electric field interference between the nozzles 100 spraying the solution.

[0100] At this time, the control unit 160 may also control not only the nozzle 100 adjacent to the nozzle 100 to spray the solution to be grounded, but also the first electrodes 120 of all remaining nozzles 100 that are not spraying the solution to be grounded.

[0101] 9 , the distance B between the first electrodes 120 of adjacent nozzles 100 is preferably greater than the distance A between the lower end of the nozzle 100 and the printed object S. In this case, the electric field interference between adjacent nozzles 100 can be minimized, and thus each nozzle 100 can be independently controlled to eject the solution.

[0102] The distance B between the first electrodes 120 of adjacent nozzles 100 is a fixed value during manufacturing. Therefore, when using the inkjet print head of this embodiment, it is preferred to control the distance A between the lower end of the nozzle 100 and the printed object S within a range less than the B value for printing.

[0103] The scope of the present invention is not limited to the above-described embodiments and can be implemented in various forms within the scope of the attached patent application. Within the scope of the invention claimed in the patent application, various variations that can be made by those skilled in the art to which the present invention belongs are also within the scope of the present invention.

[0104] 100: Nozzle 110: Nozzle layer 110a: first nozzle layer 110b: Second nozzle layer 111: Slot 112: Nozzle chamber 114: Nozzle hole 115: protrusion 116: Connecting chamber 119: Blocking Department 120, 120a: first electrode 120b: third electrode 130, 130a, 130b: second electrode 140: compartment 142: Runner 150, 150a: first voltage controller 150b: Second voltage controller 160: Control Department 200: Grounding electrode A, B: distance S: Printed material

Claims

1. An inkjet printhead having multiple nozzles and ejecting a solution via electrohydrodynamics, wherein, include: A first electrode is formed for each of a plurality of nozzles and is either applied a voltage for spraying solution via electrohydrodynamics or grounded; a first voltage controller is used to apply voltage to the first electrode; and a control unit is used to control the grounding of the first electrode or the application of voltage to the first electrode by the first voltage controller. When the plurality of nozzles selectively spray solution, the control unit connects the first electrode of the nozzle to be sprayed with solution to the first voltage controller so that the first electrode is energized, and grounds the first electrode of the nozzle adjacent to the nozzle to be sprayed with solution that does not spray solution, wherein the distance between the first electrodes of adjacent nozzles is greater than the distance between the lower end of the nozzle and the printed material.

2. The inkjet printhead as described in claim 1, wherein, When multiple nozzles selectively spray solution, the control unit connects the first electrode of the nozzle to be sprayed with solution to the first voltage controller so that the first electrode is energized, and grounds the first electrode of the remaining nozzles that are not spraying solution.

3. The inkjet printhead as described in claim 1, wherein, The inkjet printhead includes: a nozzle layer having a plurality of nozzle chambers for storing ink supplied to each nozzle, and a nozzle orifice for ejecting solution being formed at the lower end of the nozzle chamber, and a first electrode being formed on the inner surface of the nozzle chamber.

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