Inkjet print head

Abstract

The present invention relates to an inkjet print head, which has a plurality of nozzles and ejects a solution in an electrohydrodynamic manner, and is characterized by comprising: a print head part in which a plurality of nozzles are formed; a plurality of first electrodes formed inside the nozzle for each of the plurality of nozzles; a second electrode formed inside the print head and to which a voltage for electrohydrodynamically ejecting a solution is applied; a voltage controller for applying a predetermined voltage to the second electrode; and a control unit that controls the first electrode to be grounded or not to be electrically connected for each of the plurality of nozzles, the control unit being configured to cause the solution not to be ejected when the first electrode is grounded, and cause an induced voltage to be generated on the first electrode to eject the solution when the first electrode is not electrically connected, therefore, solution injection is independently controlled for each nozzle.

Description

TECHNICAL FIELD

[0001] The present application relates to an inkjet printhead, and more particularly to an inkjet printhead having a plurality of nozzles and ejecting a solution by an electrohydrodynamic method. BACKGROUND

[0002] Generally, an inkjet printhead is a device that ejects a minute droplet of ink onto a desired position of a print medium, thereby printing an image of a prescribed color on a surface of the print medium. Recently, the inkjet printhead has been applied to various fields such as a flat panel display field of liquid crystal displays (LCDs) and organic light emitting devices (OLEDs), a flexible display field of electronic paper (E-paper), a printed electronics field of metal wiring, a biological field, etc.

[0003] In a drop-on-demand (DOD) inkjet printhead, there are known a piezoelectric inkjet printhead that ejects ink using a pressure wave generated by deformation of a piezoelectric body and an electrohydrodynamic inkjet printhead that ejects ink using an electrostatic force.

[0004] The piezoelectric inkjet printhead is a method that uses a piezoelectric body to vibrate a membrane, thereby applying pressure to a chamber containing ink to eject the ink. Generally, if a pressure is applied to a degree that can overcome the surface tension and viscosity of ink on the surface of a nozzle, a droplet is ejected, and further applied pressure should be sufficiently large so that the emitted droplet is accelerated at a speed at which the droplet can accurately land on a print medium. In a piezoelectric driving method inkjet printhead, in order to realize a droplet of several picoliters or less, it is necessary to reduce the deformation energy in a pressure chamber, but at this time, the ejection energy per unit volume of the ejected droplet is also reduced, as a result of which the ejection speed of the droplet is also reduced. If the ejection speed of the droplet is thus reduced, a problem arises in that the droplet cannot be accurately ejected onto a desired position.

[0005] A piezoelectric inkjet head has the advantages that it is easy to control the printing operation, and since the ejection energy is provided by mechanical deformation of a piezoelectric body, the ink used is not limited. However, the piezoelectric inkjet head has the limitations that it is difficult to achieve ultra-fine droplets of less than several picoliters, and it is generally only able to eject ink of a viscosity of the order of 10 cPs, and cannot eject high viscosity ink. Furthermore, due to the limitations of the ejection energy, it is difficult to eject larger droplets of more than 80 picoliters. In particular, in order to be used in printed electronics for displays and the like, the volume uniformity of the ejected droplets between multiple nozzles is very important, unlike conventional pattern printing, but the piezoelectric inkjet head has limitations in this regard.

[0006] An electrohydrodynamic inkjet head provides ejection energy by applying an electrostatic force to the liquid surface of ink formed at the tip of a nozzle, and thus has the advantages that it is able to achieve ultra-fine droplets of less than several picoliters or femtoliters, and is also able to eject droplets of high viscosity ink of the order of 1,000 cPs. Furthermore, it is also able to form larger droplets of more than 80 picoliters. Since control is performed using the distribution of the electric field formed on the nozzle, the driving method is also relatively simple, and the directionality of the ejected ink droplets is also excellent, and thus has the advantage that it is beneficial for precision printing.

[0007] However, when multiple nozzles are formed on an electrohydrodynamic inkjet head, electric field interference occurs between adjacent nozzles, resulting in non-uniformity in the size of the droplets ejected through the multiple nozzles, and there is a problem that the printing quality is degraded.

[0008] Furthermore, when multiple nozzles are formed, there is a problem that it is difficult to independently control each nozzle to eject a solution.

[0009] [Patent Document]

[0010] Patent Document: Korean Patent Publication No. 1310759 SUMMARY

[0011] The present invention has been made to solve the problems of the related art as described above, and aims to provide an inkjet head having multiple nozzles and ejecting a solution by an electrohydrodynamic method, the inkjet head being configured to have a first electrode provided for each nozzle, and to apply a predetermined voltage to a second electrode formed as a common electrode or a second electrode formed as an independent electrode for each nozzle, or to apply a predetermined voltage to ink supplied, and to independently control each nozzle such that the first electrode is grounded or not electrically connected, thereby causing an induced voltage to be generated on the first electrode to eject a solution only when the first electrode is not electrically connected, and thereby enabling the ejection of a solution to be independently controlled for each nozzle.

[0012] The problem to be solved by the present application is not limited to the technical problem mentioned above, and for other technical problems not mentioned, those skilled in the art to which the present application pertains should be able to clearly understand from the following description.

[0013] The above object can be achieved by the inkjet printhead of the present application, which has a plurality of nozzles and ejects a solution by electrohydrodynamics, characterized by comprising: a printhead portion in which a plurality of nozzles are formed; a plurality of first electrodes formed inside each of the plurality of nozzles; a second electrode formed inside the printhead portion and to which a voltage for ejecting a solution by electrohydrodynamics is applied; a voltage controller for applying a prescribed voltage to the second electrode; and a control portion for controlling the first electrode to be grounded or not electrically connected for each of the plurality of nozzles, the control portion being for causing a solution not to be ejected when the first electrode is grounded and causing an induced voltage to be generated on the first electrode to eject a solution when the first electrode is not electrically connected, thereby independently controlling the ejection of a solution for each nozzle.

[0014] Here, the second electrode can be formed as a common electrode for the plurality of nozzles.

[0015] Here, the printhead portion can include a first nozzle layer in which a plurality of nozzles are formed and a first chamber for storing supplied ink is formed for each of the plurality of nozzles, a second nozzle layer formed above the first nozzle layer and a second chamber communicating with the first chamber is formed for each of the plurality of nozzles, and the second electrode is formed on the second nozzle layer.

[0016] Here, a nozzle hole for ejecting a solution can be formed on a lower end of the second chamber.

[0017] Here, the first electrode can be formed on an inner side surface of the first chamber, and the second electrode can be formed on an inner side surface of the second chamber.

[0018] Here, a third electrode can be further included, which is arranged apart from the first electrode formed on each nozzle or is arranged apart from the second electrode formed on each nozzle, and the third electrode is grounded and functions to prevent electrical field interference between the nozzles.

[0019] Here, a third electrode can be further included, which is arranged apart from the first electrode formed on each nozzle or is arranged apart from the second electrode formed on each nozzle, and the third electrode is grounded and functions to prevent electrical field interference between the nozzles, and the third electrode can be formed on an upper side surface of the first nozzle layer or an upper side surface of the second nozzle layer.

[0020] Here, a downwardly recessed groove can be formed on the upper side of the first nozzle layer or the upper side of the second nozzle layer, and the third electrode can be formed inside the groove.

[0021] Here, the third electrode can be formed on the lower side of the first nozzle layer or the second nozzle layer.

[0022] Here, for each nozzle, a downwardly protruding protrusion can be formed on the lower end of the first nozzle layer or the second nozzle layer, and the third electrode can be formed on the concave surface between the protrusions.

[0023] Here, an upwardly recessed groove can be formed on the lower side of the first nozzle layer or the second nozzle layer, and the third electrode can be formed inside the groove.

[0024] Here, the print head can further include a partition layer disposed above the second nozzle layer and through which a flow path connected to the second chamber is formed, and the third electrode is formed on the upper side of the partition layer.

[0025] Here, a downwardly recessed groove can be formed on the upper side of the first nozzle layer or the upper side of the second nozzle layer, and the third electrode can be formed inside the groove.

[0026] Here, a blocking portion formed of an insulator can be further included to cover the groove, thereby blocking the third electrode from being exposed to the outside of the groove.

[0027] Here, the control portion can include a ground wiring for ground connecting the first electrode, and a switch formed on the ground wiring and for generating an induced voltage on the first electrode by selectively releasing the ground of the first electrode.

[0028] Further, the above object can be achieved by the inkjet print head of the present application, which has a plurality of nozzles and ejects a solution by electrohydrodynamics, characterized by comprising: a print head portion formed with a plurality of nozzles; a plurality of first electrodes formed inside each of the nozzles for the plurality of nozzles; a voltage controller for applying a prescribed voltage to ink inside the print head portion; and a control portion for controlling the first electrode to be grounded or not electrically connected for each of the plurality of nozzles, the control portion for causing the solution not to be ejected when the first electrode is grounded and for causing an induced voltage to be generated on the first electrode to eject the solution when the first electrode is not electrically connected, thereby independently controlling the solution ejection for each nozzle.

[0029] The inkjet print head according to the present application as described above, which is an inkjet print head having a plurality of nozzles and ejecting a solution by electrohydrodynamics, has an advantage that the solution ejection can be easily controlled for individual nozzles.

[0030] Furthermore, droplets are ejected from a plurality of nozzles by an electrohydrodynamic method, and electric field interference between adjacent nozzles is minimized, thereby having the advantages of easy control and uniform droplet ejection. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a diagram showing a schematic structure of an inkjet print head according to a first embodiment of the present invention.

[0032] Figure 2 Yes Figure 1 A diagram showing a schematic structure of an inkjet print head according to a modified example.

[0033] Figures 3 to 5 This is a diagram showing a schematic structure of an inkjet print head according to another modified example of the third electrode.

[0034] Figure 6 It is a diagram showing a schematic structure of an inkjet print head according to a second embodiment of the present invention.

[0035] Figure 7 It is a diagram showing a schematic structure of an inkjet print head according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0036] The detailed description and drawings include details of the embodiments.

[0037] The advantages and features of the present invention, as well as the methods for achieving these advantages and features, will be clearly understood by reference to the accompanying 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 only to fully disclose the present invention and to fully inform those having ordinary knowledge in the field to which the present invention belongs. The present invention is defined by the scope of the claims. Throughout the specification, the same reference numerals represent the same structural elements.

[0038] Hereinafter, the present invention will be described in detail by way of embodiments of the present invention with reference to the accompanying drawings for explaining an inkjet print head.

[0039] Figure 1 is a diagram showing a schematic structure of an inkjet print head according to a first embodiment of the present invention.

[0040] An inkjet printhead according to an embodiment of the present application has a plurality of nozzles 100 each of which can eject a solution by electrohydrodynamics using an electrostatic force. Although two nozzles 100 are shown to be formed in the horizontal direction, this is for illustration only, and a larger number of nozzles 100 can be formed. Further, a plurality of nozzles 100 can be arranged in the front-to-back paper surface direction as well, and a plurality of nozzles 100 can be formed in a matrix shape.

[0041] An inkjet printhead according to an embodiment of the present application can be configured to include a printhead portion, a first electrode 130, a second electrode 140, a voltage controller 160, and a control portion.

[0042] The printhead portion forms the outer shape of the inkjet printhead. The printhead portion is formed with a plurality of nozzles 100. Further, a chamber for storing ink supplied from the outside can be formed.

[0043] In the present embodiment, the printhead portion can be formed to include a first nozzle layer 110 and a second nozzle layer 120. Further, a partition layer 180 can be further included.

[0044] A plurality of first chambers 112 for storing ink supplied from the outside are formed spaced apart on the first nozzle layer 110, and a nozzle hole 113 for ejecting a solution is formed at the lower end of the first chamber 112. Each nozzle 100 ejects a solution supplied into the first chamber 112 to the outside through the nozzle hole 113. At this time, as shown in the drawing, the first chamber 112 can be formed in a conical frustum shape with an inclined surface formed on the inside so that the cross-sectional size becomes smaller as it approaches the lower portion, but is not limited thereto and can be formed in a cylindrical shape.

[0045] For each nozzle 100, the lower end portion of the first nozzle layer 110 can be formed with a protrusion 111, and the nozzle hole 113 can be formed at the lower end of the protrusion 111.

[0046] A first electrode 130 can be arranged for each of the plurality of nozzles 100, and the first electrode 130 can be grounded or electrically disconnected by control of the control portion. As shown in the drawing, the first electrode 130 can be formed on the inner side surface of the first chamber 112. Although the first electrode 130 is formed on the entire inner side surface of the first chamber 112 in the drawing, it can be formed partially on a portion of the inner side surface of the first chamber 112. Further, the upper end portion of the first electrode 130 can also be partially extended to be formed on the upper surface of the first nozzle layer 110.

[0047] Although not shown, the first electrode 130 can also be coated with an insulating layer. When the first electrode 130 is coated with an insulating layer, as described later, when an induced voltage is generated on the first electrode 130, the solution flowing into the inside of the first chamber 112 can be induced to be charged, and the charged solution can be ejected to the outside through the nozzle hole 113 by the force of the electric field formed by the first electrode 130 and the second electrode 140.

[0048] For each of the plurality of nozzles 100, the control portion controls the first electrode 130 to be grounded or de-grounded so as not to be electrically connected. The control portion can be composed of a ground wire for grounding the first electrode 130 and a switch 150 formed on the ground wire. Thus, when the switch 150 is on, the first electrode 130 is grounded, and when the switch 150 is off, the grounding of the first electrode 130 is de-grounded so as not to be electrically connected. When the first electrode 130 is not electrically connected, an induced voltage can be generated on the first electrode 130 by the second electrode 140 to which a high voltage is applied. Note that, although the control portion is shown on only one nozzle 100 in the drawing, in fact, the control portion is formed on each nozzle 100.

[0049] At this time, the control portion does not cause the plurality of first electrodes 130 separately formed for the plurality of nozzles 100 to be commonly grounded or de-grounded, but causes each first electrode 130 to be independently grounded or de-grounded. As described later, the nozzle 100 of which the first electrode 130 is grounded does not eject the solution. For the nozzle 100 of which the first electrode 130 is not electrically connected, an induced voltage is generated on the first electrode 130 by the second electrode 140 to which a prescribed voltage is applied. At this time, the solution can be ejected by the force of the electric field caused by the voltage induced on the first electrode 130 and the voltage applied to the second electrode 140. Thus, the ejection of the solution can be controlled for each nozzle 100 independently by the on / off control of the switch 150 for the plurality of nozzles 100.

[0050] The second nozzle layer 120 is formed on the upper side of the first nozzle layer 110. A plurality of second chambers 122 are separately formed on the second nozzle layer 120. The second chambers 122 are formed for each nozzle 100 and communicate with and pass through the first chambers 112 of the first nozzle layer 110. The second chambers 122 also form a space for storing the ink supplied from the outside for each nozzle 100 as with the first chambers 112. The second chambers 122 can be formed in a cylindrical shape extending from the upper end of the first chamber 112, but are not necessarily limited thereto.

[0051] The second electrode 140 is formed inside the print head. The second electrode 140, to which a voltage for ejecting a solution by electrohydrodynamics is applied, can be provided for each of the plurality of nozzles 100. As shown, the second electrode 140 can be formed on the inner side of the second chamber 122. As with the first electrode 130, the second electrode 140 can be formed on the entire inner side of the second chamber 122, or partially on a portion of the inner side of the second chamber 122. In addition, the upper end of the second electrode 140 can partially extend onto the upper surface of the second nozzle layer 120.

[0052] Although not shown, the second electrode 140 can also be coated with an insulating layer, as with the first electrode 130.

[0053] The voltage controller 160 applies a voltage for ejecting a solution by electrohydrodynamics to the second electrode 140. At this time, for the plurality of nozzles 100, a prescribed voltage can be applied to the second electrode 140 at all times. Note that, although it is shown in the drawing that the voltage controller 160 is connected to only one of the second electrodes 140, in fact, a plurality of second electrodes 140 can be connected to the voltage controller 160 and applied with a prescribed voltage.

[0054] In addition, as will be described later Figure 6 with reference to FIG. 6, the second electrode 140 formed corresponding to each nozzle 100 can also be formed as a common electrode, rather than as an independent electrode. That is, the second electrodes 140 can be connected to each other to form one common electrode, rather than being spaced apart from each other as shown in Figure 1 FIG. 6 for each nozzle 100. For example, the second electrode 140 can be formed as one flat electrode on the upper side of the second nozzle layer 120.

[0055] A ground electrode 200, to which a voltage of opposite polarity to that applied to the first electrode 130 and the second electrode 140 or ground is applied, can be formed below the object S to be printed. Further, the ground electrode 200 can also be electrically disconnected. The ground electrode 200 forms a potential difference with the second electrode 140 to which a prescribed voltage is applied and the first electrode 130 to generate an induced voltage, thereby more uniformly forming an electric field for ejecting by electrohydrodynamics between the nozzle 100 and the object S to be printed.

[0056] In this way, the first electrode 130 and the second electrode 140 are separated so as not to be connected to each other, and the first electrode 130 can be grounded or generate an induced voltage by the control of the control unit, and the second electrode 140 can be connected to the voltage controller 160 and applied with a prescribed voltage.

[0057] The first electrode 130 and the second electrode 140 can each be an electrode for forming an electric field between the nozzle 100 and the print object S in order to eject a solution by electrohydrodynamics.

[0058] That is, in the present application, the nozzle layer 110, 120 is formed in a state of being laminated by two layers, so that a solution can be ejected to the outside through the nozzle hole 113 by the force of the electric field caused by the voltage applied to the first electrode 130 and the second electrode 140.

[0059] In the present application, a predetermined voltage can be applied to the second electrode 140 formed on the second nozzle layer 120 by the voltage controller 160, and each of the first electrodes 130 formed on the first nozzle layer 110 can be controlled to be grounded or not electrically connected by controlling the on and off of the switch 150. At this time, each nozzle 100 can be independently controlled to eject or not eject a solution according to the electrically connected state of the first electrode 130 by controlling the switch 150 of each nozzle 100. That is, in a state where a predetermined voltage is applied to the second electrode 140, when the switch 150 is turned on and the first electrode 130 is not electrically connected, a predetermined size of induced voltage is generated on the first electrode 130 by the second electrode 140 to which a high voltage is applied, so that a solution can be ejected by the electrostatic force caused by the voltage applied to the second electrode 140 and the induced voltage generated on the first electrode 130. In addition, in a state where a predetermined voltage is applied to the second electrode 140, when the switch 150 is turned off and the first electrode 130 is grounded, no induced voltage is generated on the first electrode 130 and 0V is applied, so that a solution cannot be ejected only by the voltage applied to the second electrode 140.

[0060] Therefore, for a plurality of nozzles 100, the control part can selectively ground or unground the first electrode 130 and selectively eject ink only from the nozzle 100 in which the induced voltage is generated by the second electrode 140 due to the ungrounding of the first electrode 130.

[0061] The third electrode 170 can be spaced apart from the first electrode 130 formed on each nozzle 100 or spaced apart from the second electrode 140, and the third electrode 170 is grounded. With the third electrode 170 grounded between the nozzles 100, the electric field interference between adjacent nozzles 100 can be minimized. Note that, although only one third electrode 170 is shown as being grounded in the drawing, in fact, all of the third electrodes 170 shown in the drawing are grounded.

[0062] At this time, as shown in FIG. 4, in the present embodiment, the third electrode 170 can be formed on the upper side of the first nozzle layer 110 or the upper side of the second nozzle layer 120 at a position spaced apart from the first electrode 130 or the second electrode 140 between the nozzles 100. Figure 1 At this time, as shown in FIG. 4, in the present embodiment, the third electrode 170 can be formed on the upper side of the first nozzle layer 110 or the upper side of the second nozzle layer 120 at a position spaced apart from the first electrode 130 or the second electrode 140 between the nozzles 100.

[0063] At this time, as shown in an enlarged view of Figure 1 , the distance B between the adjacent first electrode 130 and the third electrode 170 or the distance B between the adjacent second electrode 140 and the third electrode 170 is preferably greater than the distance A between the lower end of the nozzle 100 and the printed matter S. At this time, the electric field interference between the nozzles 100 can be minimized, and for each nozzle 100, the solution can be ejected by independent control. When the distance B is less than the distance A between the lower end of the nozzle 100 and the printed matter S, it is difficult to independently eject the solution by each nozzle 100. Here, the distance B between the first electrode 130 and the third electrode 170 or the distance B between the second electrode 140 and the third electrode 170 can mean the minimum distance between the ends of the two electrodes.

[0064] The distance B is a fixed value at the time of manufacturing the inkjet print head, and thus when the inkjet print head according to the present application is used, it is preferable to control the distance A between the lower end of the nozzle 100 and the printed matter S in a range less than the value of B to perform printing.

[0065] Figure 1 is a view showing a schematic structure of an inkjet print head which is a modification of Figure 2 .

[0066] In the following description, the description will be made centering on the difference from the embodiment described above with reference to Figure 1 .

[0067] In the present embodiment, the rest of the structure is the same as that of the embodiment of Figure 1 except for the second nozzle layer 120.

[0068] In the present embodiment, the nozzle hole 123 for ejecting the solution can be formed at the lower end of the second chamber 122 of the second nozzle layer 120. That is, the nozzle hole 123 for ejecting the fine droplet is also formed on the second nozzle layer 120, and thus the second nozzle layer 120 can be formed in the same form as the first nozzle layer 110. The first chamber 112 of the first nozzle layer 110 and the second chamber 122 of the second nozzle layer 120 are communicated through the nozzle hole 123, but not in the form of smoothly extending as in Figure 1 .

[0069] In the present embodiment, the second electrode 140 formed on the second nozzle layer 120 is also applied with the prescribed voltage by the voltage controller 160, and the first electrode 130 formed on the first nozzle layer 110 can be independently controlled to be grounded or not to be electrically connected, and thus the solution ejection can be independently controlled for each nozzle 100.

[0070] Further, a third electrode 170 can be formed, thereby enabling to control ejection of solution by individual nozzle 100 using electrohydrodynamics while minimizing electric field interference between adjacent nozzles 100.

[0071] In the following description, reference is made to Figure 1 A modification of the aforementioned third electrode 170 will be described.

[0072] Figures 3 to 5 is a diagram showing a schematic structure of an inkjet printhead showing other modifications related to the third electrode 170.

[0073] In Figures 3 to 5 the embodiment, the shape, structure and electrical control method of the first nozzle layer 110, the first electrode 130, the second nozzle layer 120 and the second electrode 140 can be the same as in the embodiment described above with reference to Figures 3 to 5

[0074] First, as shown in Figures 1 to 2 , a groove 116 recessed downward can be formed between each nozzle 100 on the upper side of the first nozzle layer 110 or the second nozzle layer 120. The groove 116 can be formed in a shape having a length greater than a width, but is not necessarily limited thereto.

[0075] At this time, a third electrode 170 grounded can be formed inside the groove 116. Further, after forming the third electrode 170 inside the groove 116, a blocking portion 117 covering the groove 116 to block the third electrode 170 from being exposed to the outside of the groove 116 can be further formed. It is preferable that the blocking portion 117 be formed of an insulator.

[0076] With the third electrode 170 grounded formed in this structure inside the groove 116 covered by the insulator, electric field interference between adjacent nozzles 100 can be minimized.

[0077] Further, as shown in Figure 3 , the third electrode 170 can be formed between each nozzle 100 on the lower side of the first nozzle layer 110 or the second nozzle layer 120. At this time, as described above, for each nozzle 100, a protruding portion 111, 121 having a nozzle hole 113, 123 formed at a lower end can be formed below the nozzle layer 110, 120, and thus the third electrode 170 can be formed on the concave surface between the protruding portions 111 and / or on the concave surface between the protruding portions 121.

[0078] ​In this embodiment, the distance B between the lower end of the first nozzle layer 110 and the third electrode 170 or the distance B between the lower end of the second nozzle layer 120 and the third electrode 170 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, allowing each nozzle 100 to be independently controlled to eject the solution without causing wetting. However, when the distance B is less than the distance A between the lower end of the nozzle 100 and the printed object S, the electric field interference between adjacent nozzles 100 makes it difficult to control the independent ejection of the solution through each nozzle 100, and wetting may occur.

[0079] In this embodiment, the distance B is also a fixed value during manufacturing. Therefore, when using the inkjet print head according to the present invention, 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.

[0080] Although not shown in the figure, Figure 4 For illustration, an upwardly recessed groove 116 may be formed on the lower side of each nozzle layer 110, 120, and a third electrode 170 may be formed inside the groove 116. Similarly, the groove 116 is preferably covered by a blocking portion 117 as an insulator to prevent the third electrode 170 from being exposed to the outside.

[0081] In addition, if Figure 3 As shown, a partition layer 180 may be further included above the second nozzle layer 120. The partition layer 180 may be formed above the second nozzle layer 120 and may have a flow channel 182 formed therethrough, connected to the second chamber 122. No electrodes are formed within the flow channel 182. The partition layer 180 may be formed from a thin sheet (wafer) of insulating material of a predetermined thickness.

[0082] At this time, a grounded third electrode 170 may be formed on the upper side of the partition layer 180. Similarly, the third electrode 170 may prevent electric field interference between adjacent nozzles 100.

[0083] Compared with the above embodiment, the distance B between the second electrode 140 and the third electrode 170 can be kept relatively far by the partition layer 180 , so that 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.

[0084] Although not shown in the figure, Figure 5 For illustration, a recessed groove 116 may be formed on the upper side of the spacer 180, and the third electrode 170 may be formed inside the groove 116. Similarly, the groove 116 is preferably covered by a blocking portion 117 as an insulator to prevent the second electrode 140 from being exposed to the outside.

[0085] Figure 3 Fig. 2 is a diagram showing a schematic structure of an inkjet printhead according to a second embodiment of the present application.

[0086] In the present embodiment, explanation will be made focusing on the difference from the embodiment explained above with reference to Fig. 1. Figure 6

[0087] In the foregoing embodiment, the printhead portion is formed with the first nozzle layer 110 and the second nozzle layer 120, and the chamber formed with the first chamber 112 and the second chamber 122 is formed independently for each nozzle 100, but in the present embodiment, the printhead portion 310 is formed with a common chamber 312 which is a chamber connecting the chambers 312 of the plurality of nozzles 100 to each other.

[0088] Further, the second electrode 140 is not formed independently for each electrode, but is formed as a common electrode inside the chamber 312.

[0089] At this time, the first electrode 130 is formed for each nozzle 100, and the control portion is formed independently for each first electrode 130. Also in the present embodiment, an induced voltage can be further generated on the first electrode 130 only in the nozzle 100 controlled to be ungrounded and not electrically connected, so that the solution is ejected by the force of the electric field.

[0090] Although not shown, a third electrode 170 grounded can be formed between the plurality of nozzles 100.

[0091] Figures 1 to 5 Fig. 4 is a diagram showing a schematic structure of an inkjet printhead according to a third embodiment of the present application.

[0092] In the present embodiment, explanation will be made focusing on the difference from the embodiment explained above with reference to Fig. 1. Figure 7 Figures 1 to 6

[0093] In the present embodiment, the second electrode 140 is not formed, but a voltage controller 160 for applying a prescribed voltage is directly connected to the solution inside the printhead portion 310 to electrify the solution.

[0094] As in the foregoing embodiment, the first electrode 130 is formed independently for each nozzle 100, and the control portion is formed independently for each first electrode 130, and an induced voltage can be further generated only in the nozzle 100 controlled to be ungrounded and not electrically connected, so that the solution is ejected by the force of the electric field.

[0095] ​​The scope of the present invention is not limited to the above-described embodiments, and can be implemented in various modes of embodiments within the scope of the appended claims. Various modifications can be made by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention as claimed in the claims, and such modifications also belong to the scope of the present invention as claimed in the claims.

Claims

1. An inkjet printhead having a plurality of nozzles and ejecting a solution by electrohydrodynamics, characterized by, Comprising: a print head portion formed with a plurality of nozzles; a plurality of first electrodes formed inside each of the plurality of nozzles; a second electrode formed inside the print head portion and applied with a voltage to eject a solution by electrohydrodynamics; a voltage controller for applying a prescribed voltage to the second electrode; and a control portion for controlling the first electrode to be grounded or not electrically connected for each of the plurality of nozzles, the control portion for causing the solution not to be ejected when the first electrode is grounded and for causing an induced voltage to be generated on the first electrode to eject the solution when the first electrode is not electrically connected, thereby independently controlling the solution ejection for each nozzle.

2. The inkjet print head according to claim 1, wherein the second electrode is formed as a common electrode for the plurality of nozzles.

3. The inkjet print head according to claim 1, wherein the print head portion includes: a first nozzle layer formed with a plurality of nozzles and formed with a first chamber for storing ink supplied for each of the plurality of nozzles; a second nozzle layer formed above the first nozzle layer and formed with a second chamber communicating with the first chamber for each of the plurality of nozzles, and the second electrode is formed on the second nozzle layer.

4. The inkjet print head according to claim 3, wherein a nozzle hole for ejecting a solution is formed on a lower end of the second chamber.

5. The inkjet print head according to claim 3, wherein the first electrode is formed on an inner side surface of the first chamber, and the second electrode is formed on an inner side surface of the second chamber.

6. The inkjet print head according to claim 1, further comprising: a third electrode disposed apart between the first electrodes formed on each nozzle or between the second electrodes formed on each nozzle, and grounded and for preventing electric field interference between the nozzles.

7. The inkjet print head according to claim 3, wherein further comprising: a third electrode disposed apart between the first electrodes formed on each nozzle or between the second electrodes formed on each nozzle, and grounded and for preventing electric field interference between the nozzles, the third electrode is formed on an upper side surface of the first nozzle layer or an upper side surface of the second nozzle layer.

8. The inkjet print head according to claim 7, wherein a downwardly recessed groove is formed on the upper side surface of the first nozzle layer or the upper side surface of the second nozzle layer, and the third electrode is formed inside the groove.

9. The inkjet print head according to claim 7, wherein the third electrode is formed on a lower side surface of the first nozzle layer or the second nozzle layer.

10. The inkjet print head according to claim 9, wherein for each nozzle, a downwardly protruding protrusion is formed on a lower end portion of the first nozzle layer or the second nozzle layer, and the third electrode is formed on a concave surface between the protrusions. ​ 11. The inkjet printhead according to claim 9, wherein a groove recessed upward is formed on an underside of the first nozzle layer or the second nozzle layer, and the third electrode is formed inside the groove.

12. The inkjet printhead according to claim 7, wherein the printhead further includes a partition layer disposed above the second nozzle layer and through which a flow path connected to the second chamber is formed, the third electrode is formed on an upper side of the partition layer.

13. The inkjet printhead according to claim 12, wherein a groove recessed downward is formed on an upper side of the partition layer, and the third electrode is formed inside the groove.

14. The inkjet printhead according to any one of claims 8, 11 and 13, further comprising: a blocking portion formed of an insulator and covering the groove, thereby blocking the third electrode from being exposed to the outside of the groove.

15. The inkjet printhead according to claim 1, wherein the control portion includes: a ground wiring for grounding the first electrode; and a switch formed on the ground wiring and for generating an induced voltage on the first electrode by selectively releasing grounding of the first electrode.

16. An inkjet printhead having a plurality of nozzles and ejecting a solution by electrohydrodynamics, characterized in that, comprising: a printhead formed with a plurality of nozzles; a plurality of first electrodes formed inside each of the nozzles; a voltage controller for applying a prescribed voltage to ink inside the printhead; and a control portion for controlling the first electrode to be grounded or not electrically connected for each of the nozzles, the control portion for causing solution not to be ejected when the first electrode is grounded and for causing an induced voltage to be generated on the first electrode to eject solution when the first electrode is not electrically connected, thereby independently controlling solution ejection for each nozzle.

Images