Inkjet printing device

Abstract

An inkjet printing device is provided. The inkjet printing device includes a stage on which a target substrate is placed, and an inkjet head located above the stage, wherein the inkjet head includes a discharge section in which a plurality of nozzles for spraying ink containing a plurality of particles are arranged, a filter section arranged above the discharge section and selectively passing the plurality of particles, and an electric field forming electrode arranged in the filter section and forming an electric field in the filter section.

Description

Technology Field

[0001] The present invention relates to an inkjet printing device. Background Technology

[0002] The importance of display devices is increasing along with the development of multimedia. In response to this, various types of display devices, such as Organic Light Emitting Displays (OLEDs) and Liquid Crystal Displays (LCDs), are being used.

[0003] A device for displaying images of a display device includes a display panel such as an organic light-emitting display panel or a liquid crystal display panel. Among these, as a light-emitting display panel, it may include a light-emitting element; for example, in the case of a light-emitting diode (LED), there are organic light-emitting diodes (OLEDs) that use organic materials as light-emitting materials, and inorganic light-emitting diodes that use inorganic materials as light-emitting materials.

[0004] Meanwhile, an inkjet printing device may be used to form an organic layer included in a display device or to align an inorganic light-emitting diode. After printing any ink or solution with an inkjet, a post-processing step may be performed to transfer the inorganic light-emitting diode element or to form an organic layer. The inkjet printing device may supply a predetermined ink or solution to an inkjet head, and the inkjet head may perform a process of spraying the ink or solution onto a substrate to be processed (e.g., a target substrate). The problem to be solved

[0005] The problem that the present invention aims to solve is to provide an inkjet printing device that prevents nozzle clogging caused by the sedimentation of particles in the ink remaining in the inkjet head during the non-spray mode (printing waiting time).

[0006] The problems of the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0007] An inkjet printing device according to one embodiment for solving the above problem includes a stage on which a target substrate is placed, and an inkjet head located above the stage, wherein the inkjet head includes a discharge unit having a plurality of nozzles for spraying ink containing a plurality of particles, a filter unit disposed above the discharge unit and selectively passing the plurality of particles, and an electric field forming electrode disposed in the filter unit and forming an electric field in the filter unit.

[0008] An inkjet printing device according to another embodiment for solving the above problem includes a stage on which a target substrate is placed, and an inkjet head located above the stage, wherein the inkjet head includes a plurality of nozzles for spraying ink containing a plurality of particles, a first electrode filter disposed above the plurality of nozzles and having a plurality of first holes, and a second electrode filter disposed overlapping with the first electrode filter above the first electrode filter and having a plurality of second holes.

[0009] Specific details of other embodiments are included in the detailed description and drawings. Effects of the invention

[0010] According to an inkjet printing device of one embodiment, the inkjet head may include an inner tube, a plurality of nozzles disposed at the bottom of the inner tube, and a filter portion disposed between the plurality of nozzles and the inner tube, wherein an electric field generating electrode is disposed therein. The electric field generating electrode can form an electric field inside the inkjet head in a non-spraying mode and can induce the flow of ink remaining inside the inkjet head by means of the electric field. Accordingly, in a non-spraying mode, particles within the ink remaining in the inkjet head can be prevented from settling or settling downwards inside the inkjet head, thereby preventing clogging of the nozzles.

[0011] The effects according to the embodiments are not limited to those exemplified above, and a wider variety of effects are included in this specification. Brief explanation of the drawing

[0012] FIG. 1 is a plan view of a display device according to one embodiment. FIG. 2 is a planar layout diagram showing one pixel of a display device according to one embodiment. Figure 3 is a cross-sectional view showing an example of cutting along the line I-I' of Figure 2. FIG. 4 is a schematic perspective view of a light-emitting element according to one embodiment. Figure 5 is an enlarged cross-sectional view showing an example of an enlarged area A of Figure 3. FIG. 6 is a schematic perspective view of an inkjet printing device according to one embodiment. FIG. 7 is a schematic plan view of a print head unit according to one embodiment. FIG. 8 is a schematic diagram showing the operation of a print head unit according to one embodiment. FIG. 9 is a schematic cross-sectional view of an inkjet head according to one embodiment. FIG. 10 is a plan view of the first and second electric field generating electrodes according to one embodiment. FIG. 11 is a schematic cross-sectional view for comparing the size between holes and particles of the first and second electric field generating electrodes according to one embodiment. FIGS. 12 and FIGS. 13 are schematic cross-sectional views illustrating the operation of an inkjet head according to one embodiment. Figure 14 is an enlarged view showing an example of region B of Figure 12 enlarged. FIG. 15 is a schematic cross-sectional view of an inkjet head according to another embodiment. FIG. 16 is a schematic cross-sectional view of an inkjet head according to another embodiment. Specific details for implementing the invention

[0013] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in other forms. That is, the present invention is defined only by the scope of the claims.

[0014] When elements or a layer are referred to as being "on" or "on" another element or layer, it includes not only being directly on top of the other element or layer but also cases where another layer or element is interposed in between. On the other hand, when an element is referred to as being "directly on" or "directly on," it indicates that no other element or layer is interposed in between.

[0015] The same reference numerals are used for identical or similar parts throughout the specification.

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a plan view of a display device according to one embodiment.

[0018] Referring to FIG. 1, the display device (10) displays a video or a still image. The display device (10) may refer to any electronic device that provides a display screen. For example, a television, laptop, monitor, billboard, Internet of Things, mobile phone, smartphone, tablet PC (Personal Computer), electronic watch, smart watch, watch phone, head-mounted display, mobile communication terminal, electronic notebook, e-book, PMP (Portable Multimedia Player), navigation, game console, digital camera, camcorder, etc. that provide a display screen may be included in the display device (10).

[0019] The display device (10) includes a display panel that provides a display screen. Examples of display panels include an inorganic light-emitting diode display panel, an organic light-emitting diode display panel, a quantum dot light-emitting diode display panel, a plasma display panel, a field emission display panel, etc. In the following examples, an inorganic light-emitting diode display panel is used as an example of a display panel, but it is not limited thereto, and if the same technical concept is applicable, it can be applied to other display panels.

[0020] In the drawings describing the display device (10) below, the X-axis direction (X), the Y-axis direction (Y), and the Z-axis direction (Z) are defined. The X-axis direction (X) and the Y-axis direction (Y) may be directions perpendicular to each other within a single plane. The Z-axis direction (Z) may be a direction perpendicular to the plane where the X-axis direction (X) and the Y-axis direction (Y) are located. The Z-axis direction (Z) is perpendicular to each of the X-axis direction (X) and the Y-axis direction (Y). In the embodiment describing the display device (10), the Z-axis direction (Z) represents the thickness direction of the display device (10).

[0021] The display device (10) may have a rectangular shape that includes a long side and a short side where the X-axis direction (X) is longer than the Y-axis direction (Y) in a planar plane. The corners where the long and short sides of the display device (10) meet may be right angles, but are not limited thereto, and may have a rounded curved shape. The shape of the display device (10) is not limited to the examples provided and may be varied in many ways. For example, the display device (10) may have a planar square, a square with rounded corners (vertices), other polygons, circles, or other shapes.

[0022] The display surface of the display device (10) may be positioned on one side of the Z-axis direction (Z), which is the thickness direction. Unless otherwise noted in the embodiments, when describing the display device (10), “top” indicates the display direction on one side of the Z-axis direction (Z), and likewise, “top surface” indicates a surface facing one side of the Z-axis direction (Z). Additionally, “bottom” indicates the opposite direction of the display direction on the other side of the Z-axis direction (Z), and “bottom surface” indicates a surface facing the other side of the Z-axis direction (Z). Additionally, “left,” “right,” “top,” and “bottom” indicate the direction when the display device (10) is viewed from a plane. For example, “right” indicates one side of the X-axis direction (X), “left” indicates the other side of the X-axis direction (X), “top” indicates one side of the Y-axis direction (Y), and “bottom” indicates the other side of the Y-axis direction (Y).

[0023] The display device (10) may include a display area (DPA) and a non-display area (NDA). The display area (DPA) is an area where a screen can be displayed, and the non-display area (NDA) is an area where a screen is not displayed. The display area (DPA) may be an area where a light-emitting element (ED, see FIG. 2) is ejected during the process of manufacturing the display device (10) using an inkjet printing device (1000, see FIG. 6) described later.

[0024] The shape of the display area (DPA) can follow the shape of the display device (10). For example, the shape of the display area (DPA) may have a planar rectangular shape similar to the overall shape of the display device (10). The display area (DPA) may generally occupy the center of the display device (10).

[0025] A display area (DPA) may include a plurality of pixels (PX). The plurality of pixels (PX) may be arranged in a matrix direction. The shape of each pixel (PX) may be a planar rectangle or a square. Each pixel (PX) may include a light-emitting element made of inorganic particles. The light-emitting element may be placed within each pixel (PX) through an inkjet printing process by an inkjet printing device (1000, see FIG. 6).

[0026] A non-display area (NDA) may be placed around a display area (DPA). The non-display area (NDA) may surround the display area (DPA) in whole or in part. The non-display area (NDA) may form the bezel of the display device (10).

[0027] FIG. 2 is a planar layout diagram showing one pixel of a display device according to one embodiment.

[0028] Referring to FIG. 2, each pixel (PX) of the display device (10) may include a light-emitting region (EMA) and a non-light-emitting region. The light-emitting region (EMA) is a region where light emitted from a light-emitting element (ED) is emitted, and the non-light-emitting region can be defined as a region where light is not emitted because the light emitted from the light-emitting element (ED) does not reach.

[0029] The light-emitting region (EMA) may include a region where a light-emitting element (ED) is placed and an adjacent region. Additionally, the light-emitting region may further include a region where light emitted from the light-emitting element (ED) is reflected or refracted by another member and emitted.

[0030] Each pixel (PX) may further include a sub-region (SA) disposed in a non-emissive region. A light-emitting element (ED) may not be disposed in the sub-region (SA). The sub-region (SA) may be disposed above the light-emitting region (EMA) within a pixel (PX) (or on one side in the Y-axis direction (Y). The sub-region (SA) may be disposed between the light-emitting regions (EMA) of adjacent pixels (PX) disposed in the Y-axis direction (Y). The sub-region (SA) may include a region where the electrode layer (200) and the contact electrode (700) are electrically connected through the contact portions (CT1, CT2) described later.

[0031] A sub-region (SA) may include a separation portion (ROP). The separation portion (ROP) of the sub-region (SA) may be a region in which the first electrode (210) and the second electrode (220), each included in the electrode layer (200) included in each pixel (PX) adjacent to each other along the Y-axis direction (Y), are separated from each other.

[0032] The display device (10) may include a first bank (400), an electrode layer (200), a contact electrode (700), a plurality of light-emitting elements (ED), and a second bank (600).

[0033] The electrode layer (200) may be disposed across the light-emitting region (EMA) and the sub-region (SA). The electrode layer (200) may include a plurality of electrodes that extend in the Y-axis direction (Y) and are spaced apart from each other in the X-axis direction (X). For example, the electrode layer (200) may include a first electrode (210) and a second electrode (220).

[0034] The first electrode (210) and the second electrode (220) are arranged across the light-emitting region (EMA) and sub-region (SA) of each pixel (PX), and may be spaced apart from each other in the separation portion (ROP) located in the sub-region (SA) and the first electrode (210) and the second electrode (220) included in the pixel (PX) adjacent in the Y-axis direction (Y).

[0035] The first electrode (210) and the second electrode (220), separated from the separation section (ROP) of each pixel (PX), can be formed after a process of aligning a plurality of light-emitting elements (ED) during the manufacturing process of the display device (10). Specifically, during the process of aligning a plurality of light-emitting elements (ED) during the manufacturing process of the display device (10), an electric field can be generated using alignment lines extended in the Y-axis direction (Y), and the plurality of light-emitting elements (ED) can be aligned by receiving a dielectrophoretic force from the electric field generated on the alignment lines. After the alignment process of the light-emitting elements (ED) is performed, the plurality of alignment lines can be separated from the separation section (ROP) located in the sub-region (SA) of each pixel (PX) to form the first electrode (210) and the second electrode (220) separated from the separation section (ROP) of each pixel (PX) as shown in FIG. 2.

[0036] The first electrode (210) can be electrically connected to the circuit element layer (CCL, see FIG. 3) described later through the first electrode contact hole (CTD). The second electrode (220) can be electrically connected to the circuit element layer (CCL) through the second electrode contact hole (CTS). As the first electrode (210) is electrically connected to the circuit element layer (CCL) through the first electrode contact hole (CTD) and the second electrode (220) is electrically connected to the circuit element layer (CCL) through the second electrode contact hole (CTS), the electrical signal applied to the circuit element layer (CCL) can be transmitted to both ends of the light-emitting element (ED) through the first electrode (210) and the second electrode (220). Meanwhile, the drawing shows that the first and second electrode contact holes (CTD, CTS) are arranged to overlap the second bank (600) in the Z-axis direction (Z), but the positions of the first and second electrode contact holes (CTD, CTS) are not limited thereto.

[0037] The first bank (400) may be placed in the light-emitting region (EMA). The first bank (400) may include a plurality of sub-banks that extend in the Y-axis direction (Y) and are spaced apart from each other in the X-axis direction (X). For example, the first bank (400) may include a first sub-bank (410) and a second sub-bank (420).

[0038] The first sub-bank (410) may be overlapped with the first electrode (210) in the Z-axis direction (Z) in the light-emitting region (EMA) of each pixel (PX). The second sub-bank (420) may be overlapped with the second electrode (220) in the Z-axis direction (Z) in the light-emitting region (EMA) of each pixel (PX).

[0039] The second bank (600) is positioned across the boundaries of each pixel (PX) to distinguish neighboring pixels (PX) and to distinguish the light-emitting region (EMA) and the sub-region (SA). Specifically, the second bank (600) includes an opening that overlaps the light-emitting region (EMA) and the sub-region (SA) in the Z-axis direction (Z), respectively, thereby defining the light-emitting region (EMA) and the sub-region (SA).

[0040] The second bank (600) is positioned across the boundaries of each pixel (PX) so that, during the inkjet printing process for aligning light-emitting elements (ED) in the manufacturing process of the display device (10), ink containing a plurality of light-emitting elements (ED) dispersed therein is not mixed into adjacent pixels (PX) but is sprayed into the light-emitting region (EMA) of each pixel (PX). Additionally, the second bank (600) is positioned to surround the light-emitting region (EMA) and the sub-region (SA) so that, during the inkjet process for aligning light-emitting elements (ED) in the manufacturing process of the display device (10), it can serve as a barrier that guides the ink containing the light-emitting elements (ED) dispersed therein to be stably sprayed into the light-emitting region (EMA) rather than into the sub-region (SA).

[0041] Multiple light-emitting elements (ED) may be placed in the light-emitting region (EMA). Multiple light-emitting elements (ED) may not be placed in the sub-region (SA).

[0042] A plurality of light-emitting elements (EDs) may be arranged between the first sub-bank (410) and the second sub-bank (420) in the light-emitting region (EMA). The light-emitting elements (EDs) may have a shape that extends in one direction, and the extension direction of the light-emitting elements (EDs) may be substantially perpendicular to the extension direction of the first electrode (210) and the second electrode (220). However, not limited thereto, the extension direction of the light-emitting elements (EDs) may be arranged obliquely to the extension direction of the first electrode (210) and the second electrode (220). The light-emitting elements (EDs) may be arranged such that at least one end of each end is placed on the first electrode (210) or the second electrode (220) in the region where the first sub-bank (410) and the second sub-bank (420) are spaced apart from each other.

[0043] A plurality of light-emitting elements (EDs) may be spaced apart from each other. A plurality of light-emitting elements (EDs) may be spaced apart from each other along the Y-axis direction (Y) between the first sub-bank (410) and the second sub-bank (420).

[0044] The contact electrode (700) may be positioned across the light-emitting region (EMA) and the sub-region (SA). The contact electrode (700) may include a plurality of contact electrodes that extend in the Y-axis direction (Y) and are spaced apart from each other in the X-axis direction (X). For example, the contact electrode (700) may include a first contact electrode (710) and a second contact electrode (720).

[0045] The first contact electrode (710) may be overlapped with the first electrode (210) in the Z-axis direction (Z) in the light-emitting region (EMA) and sub-region (SA) of each pixel (PX). The first contact electrode (710) may be overlapped with one end of a plurality of light-emitting elements (ED) in the light-emitting region (EMA) of each pixel (PX).

[0046] The first contact electrode (710) may contact the first electrode (210) through the first contact portion (CT1) in the sub-region (SA) of each pixel (PX) and may contact one end of a plurality of light-emitting elements (ED) in the light-emitting region (EMA) of each pixel (PX). By the first contact electrode (710) contacting one end of the light-emitting element (ED) and the first electrode (210) respectively, the first contact electrode (710) may serve to electrically connect the one end of the light-emitting element (ED) and the first electrode (210). Meanwhile, although the drawing shows the first contact electrode (710) contacting the first electrode (210) in the sub-region (SA) of each pixel (PX), it is not limited thereto. For example, the first contact electrode (710) may contact the first electrode (210) in the light-emitting region (EMA) of each pixel (PX).

[0047] The second contact electrode (720) may be overlapped with the second electrode (220) in the Z-axis direction (Z) in the light-emitting region (EMA) and sub-region (SA) of each pixel (PX). The second contact electrode (720) may be overlapped with the other end of a plurality of light-emitting elements (ED) in the light-emitting region (EMA) of each pixel (PX).

[0048] The second contact electrode (720) may contact the second electrode (220) through the second contact portion (CT2) in the sub-region (SA) of each pixel (PX) and may contact the other end of a plurality of light-emitting elements (ED) in the light-emitting region (EMA) of each pixel (PX). By the second contact electrode (720) contacting the other end of the light-emitting element (ED) and the second electrode (220) respectively, the second contact electrode (720) may serve to electrically connect the other end of the light-emitting element (ED) and the second electrode (220). Meanwhile, although the drawing shows the second contact electrode (720) contacting the second electrode (220) in the sub-region (SA) of each pixel (PX), it is not limited thereto. For example, the second contact electrode (720) may contact the second electrode (220) in the light-emitting region (EMA) of each pixel (PX).

[0049] As described above, the first contact electrode (710) and the second contact electrode (720) may be spaced apart from each other in the X-axis direction (X). The distance between the first contact electrode (710) and the second contact electrode (720) may be smaller than the length in the extension direction of the light-emitting element (ED). Accordingly, the first contact electrode (710) and the second contact electrode (720) may be spaced apart from each other in the X-axis direction (X) and may each come into contact with both ends of the light-emitting element (ED).

[0050] Figure 3 is a cross-sectional view showing an example of cutting along the line I-I' of Figure 2.

[0051] Referring to FIG. 3, the display device (10) may include a substrate (SUB), a circuit element layer (CCL), and a light-emitting element layer (EML).

[0052] The substrate (SUB) may be a base substrate or a base member. The substrate (SUB) may be made of an insulating material such as glass, quartz, or polymer resin. The substrate (SUB) may be a rigid substrate, but may also be a flexible substrate capable of bending, folding, rolling, etc.

[0053] The circuit element layer (CCL) can be disposed on a substrate (SUB). The circuit element layer (CCL) can drive the light-emitting element layer (EML) of each pixel (PX) by including at least one transistor, etc.

[0054] The circuit element layer (CCL) may include a lower metal layer (110), a semiconductor layer (120), a first conductive layer (130), a second conductive layer (140), a third conductive layer (150), and a plurality of insulating films.

[0055] The lower metal layer (110) may be disposed on a substrate (SUB). The lower metal layer (110) may include a light-blocking pattern (BML). The light-blocking pattern (BML) may be disposed to cover at least the channel region of the active layer (ACT) of the transistor (TR) from the bottom. However, it is not limited thereto, and the light-blocking pattern (BML) may be omitted.

[0056] The lower metal layer (110) may include a material that blocks light. For example, the lower metal layer (110) may be formed of an opaque metal material that blocks the transmission of light.

[0057] A buffer layer (161) may be placed on a lower metal layer (110). The buffer layer (161) may be placed to cover the front surface of a substrate (SUB) on which the lower metal layer (110) is placed. The buffer layer (161) may serve to protect multiple transistors from moisture penetrating through the substrate (SUB), which is susceptible to moisture permeability.

[0058] The semiconductor layer (120) is placed on the buffer layer (161). The semiconductor layer (120) may include an active layer (ACT) of a transistor (TR). The active layer (ACT) of the transistor (TR) may be placed overlapping the light-blocking pattern (BML) of the lower metal layer (110) as described above.

[0059] The semiconductor layer (120) may include polycrystalline silicon, single-crystal silicon, oxide semiconductor, etc. In an exemplary embodiment, when the semiconductor layer (120) includes polycrystalline silicon, the polycrystalline silicon may be formed by crystallizing amorphous silicon. When the semiconductor layer (120) includes polycrystalline silicon, the active layer (ACT) of the transistor (TR) may include a plurality of doped regions doped with impurities and channel regions between them. In another exemplary embodiment, the semiconductor layer (120) may include an oxide semiconductor. The oxide semiconductor may be, for example, indium-tin oxide (ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-zinc-tin oxide (IZTO), indium-gallium-zinc oxide (IGZO), indium-gallium-tin oxide (IGTO), indium-gallium-zinc-tin oxide (IGZTO), etc.

[0060] A gate insulating film (162) can be disposed on a semiconductor layer (120). The gate insulating film (162) can be formed as a multilayer in which inorganic layers comprising at least one of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy) are alternately stacked.

[0061] The first conductive layer (130) may be disposed on the gate insulating film (162). The first conductive layer (130) may include the gate electrode (GE) of the transistor (TR). The gate electrode (GE) may be disposed to overlap the channel region of the active layer (ACT) and the Z-axis direction (Z), which is the thickness direction of the substrate (SUB).

[0062] The first interlayer insulating film (163) may be disposed on the first conductive layer (130). The first interlayer insulating film (163) may be disposed to cover the gate electrode (GE). The first interlayer insulating film (163) performs the function of an insulating film between the first conductive layer (130) and other layers disposed thereon, and can protect the first conductive layer (130).

[0063] The second conductive layer (140) may be disposed on the first interlayer insulating film (163). The second conductive layer (140) may include the drain electrode (SD1) of the transistor (TR) and the source electrode (SD2) of the transistor (TR).

[0064] The drain electrode (SD1) and source electrode (SD2) of the transistor (TR) can be electrically connected to both end regions of the active layer (ACT) of the transistor (TR) through contact holes penetrating the first interlayer insulating film (163) and the gate insulating film (162), respectively. Additionally, the source electrode (SD2) of the transistor (TR) can be electrically connected to the light-blocking pattern (BML) of the lower metal layer (110) through another contact hole penetrating the first interlayer insulating film (163), the gate insulating film (162), and the buffer layer (161).

[0065] The second interlayer insulating film (164) may be disposed on the second conductive layer (140). The second interlayer insulating film (164) may be disposed to cover the drain electrode (SD1) and the source electrode (SD2) of the transistor (TR). The second interlayer insulating film (164) may function as an insulating film between the second conductive layer (140) and other layers disposed thereon, and may protect the second conductive layer (140).

[0066] A third conductive layer (150) may be disposed on the second interlayer insulating film (164). The third conductive layer (150) may include a first voltage line (VL1), a second voltage line (VL2), and a conductive pattern (CDP).

[0067] The first voltage line (VL1) may overlap at least a portion of the drain electrode (SD1) of the transistor (TR) and the thickness direction of the substrate (SUB). A high potential voltage (or a first power supply voltage) supplied to the transistor (TR) may be applied to the first voltage line (VL1).

[0068] The second voltage line (VL2) can be electrically connected to the second electrode (220) through a second electrode contact hole (CTS) that penetrates the via layer (166) and passivation layer (165) described later. A low potential voltage (or, second power supply voltage) lower than the high potential voltage supplied to the first voltage line (VL1) can be applied to the second voltage line (VL2).

[0069] That is, a high potential voltage (or, first power supply voltage) supplied to the transistor (TR) is applied to the first voltage line (VL1), and a low potential voltage (or, second power supply voltage) lower than the high potential voltage supplied to the first voltage line (VL1) can be applied to the second voltage line (VL2).

[0070] The conduction pattern (CDP) can be electrically connected to the source electrode (SD2) of the transistor (TR). The conduction pattern (CDP) can be electrically connected to the source electrode (SD2) of the transistor (TR) through a contact hole penetrating the second interlayer insulating film (164). Additionally, the conduction pattern (CDP) can be electrically connected to the first electrode (210) through a first electrode contact hole (CTD) penetrating the via layer (166) and passivation layer (165) described later.

[0071] A passivation layer (165) may be placed on the third conductive layer (150). The passivation layer (165) may be placed to cover the third conductive layer (150). The passivation layer (165) may serve to protect the third conductive layer (150).

[0072] The above-described buffer layer (161), gate insulating film (162), first interlayer insulating film (163), second interlayer insulating film (164), and passivation layer (165) may each be composed of a plurality of inorganic layers stacked alternately. For example, the above-described buffer layer (161), gate insulating film (162), first interlayer insulating film (163), second interlayer insulating film (164), and passivation layer (165) may be formed as a double layer in which an inorganic layer comprising at least one of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy) is stacked, or as a multilayer in which these are stacked alternately. However, not limited thereto, the buffer layer (161), gate insulating film (162), first interlayer insulating film (163), second interlayer insulating film (164), and passivation layer (165) may be formed as a single inorganic layer including the insulating material described above.

[0073] A via layer (166) may be disposed on a passivation layer (165). The via layer (166) may have a generally flat surface regardless of the shape or presence of a pattern disposed on the underside. That is, the via layer (166) may serve to flatten the upper surface of the passivation layer (165). The via layer (166) may include an organic insulating material, such as an organic material such as polyimide (PI).

[0074] Referring to FIGS. 2 and 3, a light-emitting element layer (EML) may be disposed on a circuit element layer (CCL). The light-emitting element layer (EML) may include a first bank (400), an electrode layer (200), a first insulating layer (510), a second bank (600), a light-emitting element (ED), a second insulating layer (520), and a contact electrode (700). The light-emitting element layer (EML) may further include a protective layer (810).

[0075] The first bank (400) may be placed on the via layer (166). The first bank (400) may be placed directly on the upper surface of the via layer (166). The first sub-bank (410) and the second sub-bank (420) included in the first bank (400) may each have a structure in which at least a portion protrudes with respect to the upper surface of the via layer (166) in cross-section.

[0076] The first sub-bank (410) and the second sub-bank (420) can serve to guide a plurality of light-emitting elements (EDs) to be placed between the first electrode (210) and the second electrode (220) during the process of aligning a plurality of light-emitting elements (EDs) in the manufacturing process of the display device (10). The spaced-out space between the first sub-bank (410) and the second sub-bank (420) can provide an area where a plurality of light-emitting elements (EDs) are placed.

[0077] Additionally, the first sub-bank (410) and the second sub-bank (420) may include inclined sides and serve to change the direction of propagation of light emitted from the light-emitting element (ED) and proceeding toward the sides of the first sub-bank (410) and the second sub-bank (420) to an upward direction. That is, the first bank (400) provides a space where the light-emitting element (ED) is placed, and at the same time, can also serve as a reflective barrier that changes the direction of propagation of light emitted from the light-emitting element (ED) to an upward direction.

[0078] Meanwhile, in the drawing, each side of the plurality of sub-banks (410, 420) included in the first bank (400) is shown to be inclined in a linear shape, but is not limited thereto. For example, the side (or outer surface) of the plurality of sub-banks (410, 420) included in the first bank (400) may have a curved semicircle or semi-ellipse shape. In an exemplary embodiment, the first bank (400) may include an organic insulating material such as polyimide (PI), but is not limited thereto.

[0079] The electrode layer (200) may be disposed on the first bank (400) and the via layer (166) exposed by the first bank (400). The electrode layer (200) may be disposed across the light-emitting region (EMA) and the sub-region (SA).

[0080] The first electrode (210) and the second electrode (220) are each disposed on the via layer (166) exposed by the first bank (400) and the first bank (400) in the light-emitting region (EMA), and can be disposed on the via layer (166) in the non-light-emitting region.

[0081] In the light-emitting region (EMA), the first electrode (210) may be placed on the first sub-bank (410), and the second electrode (220) may be placed on the second sub-bank (420). In the light-emitting region (EMA), the first electrode (210) may be placed on at least one side of the first sub-bank (410) facing the second sub-bank (420), and in the light-emitting region (EMA), the second electrode (220) may be placed on at least one side of the second sub-bank (420) facing the first sub-bank (410). The first and second electrodes (210, 220) may be placed to cover one side of the first and second sub-banks (410, 420) facing each other so as to reflect light emitted from the light-emitting element (ED).

[0082] The first electrode (210) is electrically connected to the circuit element layer (CCL) through a first electrode contact hole (CTD) penetrating the via layer (166) and the passivation layer (165), and the second electrode (220) can be electrically connected to the circuit element layer (CCL) through a second electrode contact hole (CTS) penetrating the via layer (166) and the passivation layer (165). Specifically, the first electrode (210) is electrically connected to the conduction pattern (CDP) through the first electrode contact hole (CTD), and the second electrode (220) can be electrically connected to the second voltage line (VL2) through the second electrode contact hole (CTS). The first electrode (210) may contact the upper surface of the conductive pattern (CDP) exposed by the first electrode contact hole (CTD), and the second electrode (220) may contact the upper surface of the second voltage line (VL2) exposed by the second electrode contact hole (CTS). The first electrode (210) may be electrically connected to a transistor (TR) through the conductive pattern (CDP). A second power supply voltage may be applied to the second electrode (220) through the second voltage line (VL2). Meanwhile, although the drawing shows the first and second electrode contact holes (CTD, CTS) arranged to overlap with the second bank (600) in the Z-axis direction (Z), the positions of the first and second electrode contact holes (CTD, CTS) are not limited thereto.

[0083] As described above, the first electrode (210) and the second electrode (220) may be spaced apart from the first electrode (210) and the second electrode (220) included in the pixel (PX) adjacent in the Y-axis direction (Y) in the separation portion (ROP) located in the sub-region (SA). Accordingly, the via layer (166) in the area overlapping with the separation portion (ROP) may be exposed by the first electrode (210) and the second electrode (220).

[0084] The first electrode (210) and the second electrode (220) can be electrically connected to the light-emitting element (ED). The first electrode (210) and the second electrode (220) can each be connected to both ends of the light-emitting element (ED) through the first contact electrode (710) and the second contact electrode (720), respectively, and can transmit an electrical signal applied from the circuit element layer (CCL) to the light-emitting element (ED).

[0085] The electrode layer (200) may include a highly reflective conductive material. For example, the electrode layer (200) may include a metal such as silver (Ag), copper (Cu), aluminum (Al), molybdenum (Mo), titanium (Ti), etc., as a highly reflective material, or may be an alloy including aluminum (Al), nickel (Ni), lanthanum (La), etc. The electrode layer (200) may reflect light emitted from the light-emitting element (ED) and traveling toward the side of the first bank (400) in an upward direction. However, not limited thereto, the electrode layer (200) may further include a transparent conductive material. For example, the electrode layer (200) may include a material such as ITO, IZO, ITZO, etc. In some embodiments, the electrode layer (200) may have a structure in which a transparent conductive material and a highly reflective metal layer are each stacked one or more times, or may be formed as a single layer including these. For example, the electrode layer (200) may have a stacked structure such as ITO / Ag / ITO / , ITO / Ag / IZO, or ITO / Ag / ITZO / IZO.

[0086] The first insulating layer (510) may be disposed on the electrode layer (200). The first insulating layer (510) may be disposed to cover the electrode layer (200) and the via layer (166) exposed by the electrode layer (200). The first insulating layer (510) may serve to protect the electrode layer (200) and simultaneously insulate the first electrode (210) and the second electrode (220) from each other.

[0087] The first insulating layer (510) may include first and second contact portions (CT1, CT2) that expose at least a portion of the first electrode (210) and the second electrode (220). The contact electrode (700) and the electrode layer (200) may be electrically connected through the first and second contact portions (CT1, CT2) that penetrate the first insulating layer (510). Meanwhile, although the drawing shows the first and second contact portions (CT1, CT2) that expose a portion of the electrode layer (200) located in a sub-region (SA), it is not limited thereto. For example, the first and second contact portions (CT1, CT2) that expose a portion of the electrode layer (200) may be located in a light-emitting region (EMA).

[0088] The second bank (600) may be disposed on the first insulating layer (510) and formed to have a predetermined height. The height of the second bank (600) may be greater than the height of the first bank (400). By having the second bank (600) have a predetermined height and being disposed to surround the sub-region (SA), the ink in which a plurality of light-emitting elements (ED) are dispersed during the inkjet printing process for aligning the light-emitting elements (ED) during the manufacturing process of the display device (10) may be sprayed into the light-emitting region (EMA) but not into the sub-region (SA). In an exemplary embodiment, the second bank (600) may include an organic insulating material such as polyimide (PI), but is not limited thereto.

[0089] A light-emitting element (ED) may be placed on the first insulating layer (510) in the light-emitting region (EMA). The light-emitting element (ED) may be placed in the light-emitting region (EMA) but not in the sub-region (SA). The light-emitting element (ED) may be placed between the first sub-bank (410) and the second sub-bank (420) in the light-emitting region (EMA). The light-emitting element (ED) may be placed such that both ends are placed on the first electrode (210) and the second electrode (220), respectively.

[0090] A light-emitting element (ED) can emit light of a specific wavelength range. For example, a light-emitting element (ED) can emit third color light or blue light having a peak wavelength in the range of 480 nm or less, preferably in the range of 445 nm to 480 nm or less.

[0091] The second insulating layer (520) may be placed on the light-emitting element (ED). The second insulating layer (520) may be placed to partially cover the outer surface of the light-emitting element (ED), but not to cover both ends of the light-emitting element (ED). Accordingly, the width of the second insulating layer (520) may be smaller than the length of the light-emitting element (ED). The second insulating layer (520) may serve to protect the light-emitting element (ED) and simultaneously fix the light-emitting element (ED) during the manufacturing process of the display device (10).

[0092] The contact electrode (700) may be placed on the second insulating layer (520). The first contact electrode (710) and the second contact electrode (720) may be spaced apart from each other with the second insulating layer (520) in between. The first contact electrode (710) and the second contact electrode (720) may serve to electrically connect the first and second electrodes (210, 220) and the light-emitting element (ED).

[0093] The first contact electrode (710) can contact the first electrode (210) and one end of the light-emitting element (ED), respectively. Specifically, the first contact electrode (710) can contact the one end of the light-emitting element (ED) exposed by the second insulating layer (520) in the light-emitting region (EMA), and can contact the first electrode (210) exposed by the first contact portion (CT1) penetrating the first insulating layer (510) in the sub-region (SA). By the first contact electrode (710) contacting the one end of the light-emitting element (ED) and the first electrode (210), respectively, the first contact electrode (710) can serve to electrically connect the one end of the light-emitting element (ED) and the first electrode (210).

[0094] The second contact electrode (720) can contact the second electrode (220) and the other end of the light-emitting element (ED), respectively. Specifically, the second contact electrode (720) can contact the other end of the light-emitting element (ED) exposed by the second insulating layer (520) in the light-emitting region (EMA), and can contact the second electrode (220) exposed by the second contact portion (CT2) penetrating the first insulating layer (510) in the sub-region (SA). By the second contact electrode (720) contacting the other end of the light-emitting element (ED) and the second electrode (220), respectively, the second contact electrode (720) can serve to electrically connect the other end of the light-emitting element (ED) and the second electrode (220).

[0095] The contact electrode (700) may include a conductive material. For example, the contact electrode (700) may include ITO, IZO, ITZO, aluminum (Al), etc. As an example, the contact electrode (700) may include a transparent conductive material, and light emitted from the light-emitting element (ED) may pass through the contact electrode (700) and proceed toward the first electrode (210) and the second electrode (220), and may be reflected from the outer surface of the first electrode (210) and the second electrode (220).

[0096] A protective layer (810) may be placed on a contact electrode (700). The protective layer (810) is placed to cover the front surface of a substrate (SUB) and can protect a first bank (400), an electrode layer (200), a plurality of light-emitting elements (ED), a contact electrode (700), and a second bank (600) placed at the bottom.

[0097] FIG. 4 is a schematic perspective view of a light-emitting element according to one embodiment.

[0098] Referring to FIG. 4, the light-emitting element (ED) is a particle-shaped element and may have a rod or cylindrical shape having a predetermined aspect ratio. The length of the light-emitting element (ED) is greater than the diameter of the light-emitting element (ED), and the aspect ratio may be 6:5 to 100:1, but is not limited thereto.

[0099] The light-emitting element (ED) may have a size ranging from a nanometer scale (1 nm or more and less than 1 µm) to a micrometer scale (1 µm or more and less than 1 mm). In one embodiment, the light-emitting element (ED) may have both a diameter and a length of a nanometer scale or both of micrometer scales. In some other embodiments, the diameter of the light-emitting element (ED) may have a size of a nanometer scale, while the length of the light-emitting element (ED) may have a size of a micrometer scale. In some embodiments, some of the light-emitting elements (ED) may have a diameter and / or length of a nanometer scale, while other parts of the light-emitting elements (ED) may have a diameter and / or length of a micrometer scale.

[0100] In one embodiment, the light-emitting element (ED) may be an inorganic light-emitting diode. The inorganic light-emitting diode may include a plurality of semiconductor layers. For example, the inorganic light-emitting diode may include a first conductivity type (e.g., n-type) semiconductor layer, a second conductivity type (e.g., p-type) semiconductor layer, and an active semiconductor layer interposed between them. The active semiconductor layer receives holes and electrons from the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, respectively, and the holes and electrons reaching the active semiconductor layer may combine with each other to emit light.

[0101] In one embodiment, the semiconductor layers described above may be sequentially stacked along one direction, which is the length direction of the light-emitting element (ED). The light-emitting element (ED) may include a first semiconductor layer (31), a device active layer (33), and a second semiconductor layer (32) that are sequentially stacked in one direction. The first semiconductor layer (31), the device active layer (33), and the second semiconductor layer (32) may each be the first conductivity type semiconductor layer, the active semiconductor layer, and the second conductivity type semiconductor layer described above.

[0102] The first semiconductor layer (31) may be doped with a first conductivity type dopant. The first conductivity type dopant may be Si, Ge, Sn, etc. In an exemplary embodiment, the first semiconductor layer (31) may be n-GaN doped with n-type Si.

[0103] The second semiconductor layer (32) may be spaced apart from the first semiconductor layer (31) with the device active layer (33) in between. The second semiconductor layer (32) may be doped with a second conductivity type dopant such as Mg, Zn, Ca, Se, Ba, etc. In an exemplary embodiment, the second semiconductor layer (32) may be p-GaN doped with p-type Mg.

[0104] The device active layer (33) may include a material having a single or multiple quantum well structure. As described above, the device active layer (33) may emit light by the coupling of electron-hole pairs according to an electric signal applied through the first semiconductor layer (31) and the second semiconductor layer (32).

[0105] In some embodiments, the device active layer (33) may have a structure in which semiconductor materials with a large band gap energy and semiconductor materials with a small band gap energy are alternately stacked, and may include different group 3 to group 5 semiconductor materials depending on the wavelength of the light emitted.

[0106] The light emitted from the device active layer (33) can be emitted not only to both end surfaces in the longitudinal direction of the light-emitting element (ED), but also to the outer surface (or outer surface, side) of the light-emitting element. That is, the light emitted from the device active layer (33) is not limited to a single direction of emission.

[0107] The light-emitting element (ED) may further include a device electrode layer (37) disposed on the second semiconductor layer (32). The device electrode layer (37) may be in contact with the second semiconductor layer (32). The device electrode layer (37) may be an ohmic contact electrode, but is not limited thereto, and may be a Schottky contact electrode.

[0108] The device electrode layer (37) can be positioned between the second semiconductor layer (32) and the electrode to reduce resistance when the contact electrode (700) is electrically connected to both ends of the light-emitting element (ED) to apply an electrical signal to the first semiconductor layer (31) and the second semiconductor layer (32). The device electrode layer (37) may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and ITZO (Indium Tin-Zinc Oxide). The device electrode layer (37) may also include an n-type or p-type doped semiconductor material.

[0109] The light-emitting element (ED) may further include a device insulating film (38) that surrounds the outer surface of the first semiconductor layer (31), the second semiconductor layer (32), the device active layer (33), and / or the device electrode layer (37). The device insulating film (38) is arranged to surround at least the outer surface of the device active layer (33) and may extend in one direction in which the light-emitting element (ED) extends. The device insulating film (38) can perform the function of protecting the above components. The device insulating film (38) is made of materials having insulating properties and can prevent an electrical short circuit that may occur when the device active layer (33) comes into direct contact with the electrode through which an electrical signal is transmitted to the light-emitting element (ED). In addition, since the device insulating film (38) protects the outer surface of the first and second semiconductor layers (31, 32), including the device active layer (33), it can prevent a decrease in light-emitting efficiency.

[0110] Figure 5 is an enlarged cross-sectional view showing an example of an enlarged area A of Figure 3.

[0111] Referring to FIGS. 4 and 5, the light-emitting element (ED) can be arranged such that the extension direction of the light-emitting element (ED) is parallel to one surface of the substrate (SUB). A plurality of semiconductor layers included in the light-emitting element (ED) can be arranged sequentially along a direction parallel to the upper surface of the substrate (SUB). For example, the first semiconductor layer (31), the device active layer (33), and the second semiconductor layer (32) of the light-emitting element (ED) can be arranged sequentially so as to be parallel to the upper surface of the substrate (SUB).

[0112] Specifically, the light-emitting element (ED) may have a first semiconductor layer (31), an active element layer (33), a second semiconductor layer (32), and an electrode layer (37) formed sequentially in a direction horizontal to the upper surface of the substrate (SUB) across both ends of the light-emitting element (ED).

[0113] A light-emitting element (ED) may be positioned such that one end is placed on the first electrode (210) and the other end is placed on the second electrode (220). However, it is not limited thereto, and the light-emitting element (ED) may be positioned such that one end is placed on the second electrode (220) and the other end is placed on the first electrode (210).

[0114] The second insulating layer (520) may be placed on the light-emitting element (ED). The second insulating layer (520) may be placed to surround the outer surface of the light-emitting element (ED). In the area where the light-emitting element (ED) is placed, the second insulating layer (520) is placed to surround the outer surface of the light-emitting element (ED), and in the area where the light-emitting element (ED) is not placed, the second insulating layer (520) may be placed on the first insulating layer (510) exposed by the light-emitting element (ED).

[0115] The first contact electrode (710) may contact one end of the light-emitting element (ED) exposed by the second insulating layer (520). Specifically, the first contact electrode (710) may be positioned to surround the end surface of the light-emitting element (ED) exposed by the second insulating layer (520). The first contact electrode (710) may contact the element insulating film (38) and the element electrode layer (37) of the light-emitting element (ED).

[0116] The second contact electrode (720) may contact the other end of the light-emitting element (ED) exposed by the second insulating layer (520). Specifically, the second contact electrode (720) may be positioned to surround the other end surface of the light-emitting element (ED) exposed by the second insulating layer (520). The second contact electrode (720) may contact the element insulating film (38) and the first semiconductor layer (31) of the light-emitting element (ED).

[0117] The first contact electrode (710) and the second contact electrode (720) may be spaced apart from each other with the second insulating layer (520) in between. The first contact electrode (710) and the second contact electrode (720) may expose at least a portion of the upper surface of the second insulating layer (520).

[0118] The first contact electrode (710) and the second contact electrode (720) may be formed on the same layer and may contain the same material. That is, the first contact electrode (710) and the second contact electrode (720) can be formed simultaneously in a single mask process. Therefore, since an additional mask process is not required to form the first contact electrode (710) and the second contact electrode (720), the manufacturing process efficiency of the display device (10) can be improved.

[0119] FIG. 6 is a schematic perspective view of an inkjet printing device according to one embodiment. FIG. 7 is a schematic plan view of a print head unit according to one embodiment. FIG. 8 is a schematic diagram showing the operation of a print head unit according to one embodiment. FIG. 8 illustrates a front view of a print head unit (100) according to one embodiment and a probe device (7000) placed on a stage (STA).

[0120] Referring to FIGS. 6 to 8, an inkjet printing device (1000) according to one embodiment includes a print head unit (100) comprising a plurality of inkjet heads (300) and a probe device (7000). The inkjet printing device (1000) may further include a first moving unit comprising first and second rails (RL1, RL2) for moving a stage (STA), a base frame (6000), and a stage (STA).

[0121] An inkjet printing device (1000) according to one embodiment sprays a predetermined ink (90) onto a target substrate (SUBB) and can align particles dispersed in the ink (90), such as bipolar elements, onto the target substrate (SUBB). Specifically, particles dispersed in the ink (90) can be sprayed onto the target substrate (SUBB) through an inkjet head (300) of a print head unit (100). An electric field is formed by a probe device (7000) on the target substrate (SUBB) where the ink (90) is sprayed, and particles contained in the ink (90) can be aligned on the target substrate (SUBB). Meanwhile, while the printing process is not being performed, the ink (90) supplied to the inkjet head (300) may not flow within the inkjet head (300), and particles dispersed in the ink (90) may settle within the inkjet head (300).

[0122] In the drawings describing the inkjet printing device (1000), a first direction (DR1), a second direction (DR2), and a third direction (DR3) are defined. The first direction (DR1) and the second direction (DR2) may be directions perpendicular to each other within a single plane. The third direction (DR3) may be a direction perpendicular to the plane where the first direction (DR1) and the second direction (DR2) are located. In the embodiments describing the inkjet printing device (1000) below, unless otherwise noted, “top” refers to one side of the third direction (DR3), and “top surface” refers to a surface facing one side of the third direction (DR3). Additionally, “bottom” refers to the other side of the third direction (DR3), and “bottom surface” refers to a surface facing the other side of the third direction (DR3). Furthermore, “left,” “right,” “top,” and “bottom” refer to directions when viewing the inkjet printing device (1000) from a plane. For example, “right” indicates one side of the first direction (DR1), “left” indicates the other side of the first direction (DR1), “up” indicates one side of the second direction (DR2), and “down” indicates the other side of the second direction (DR2).

[0123] A target substrate (SUBB) may be provided on a probe device (7000), and the probe device (7000) forms an electric field on the upper surface of the target substrate (SUBB), and by the electric field, particles contained in the ink (90) may be aligned so that a specific end faces in one direction.

[0124] The probe device (7000) may include a substage (7100), a probe support (730), a probe unit (750), and an aligner (780).

[0125] The sub-stage (7100) can provide a space for the target substrate (SUBB) to be placed. Additionally, a probe support (730), a probe unit (750), and an aligner (780) can be placed on the sub-stage (7100). The overall planar shape of the sub-stage (7100) can follow the planar shape of the target substrate (SUBB). For example, if the target substrate (SUBB) has a rectangular shape, the overall shape of the sub-stage (7100) can be rectangular.

[0126] At least one aligner (780) may be placed on the sub-stage (7100). The aligner (780) is placed on each side of the sub-stage (7100), and the area surrounded by the plurality of aligners (780) may be an area where the target substrate (SUBB) is placed.

[0127] The probe support (730) and the probe unit (750) are placed on the sub-stage (7100). The probe support (730) can provide a space on the sub-stage (7100) where the probe unit (750) is placed.

[0128] The probe unit (750) can form an electric field on a target substrate (SUBB) prepared on a sub-stage (7100) by being placed on a probe support (730).

[0129] The stage (STA) can provide an area where the probe device (7000) is placed. The first moving unit can adjust the relative position between the stage (STA) and the print head unit (100). The first moving unit may include first and second rails (RL1, RL2).

[0130] A stage (STA) can be placed on first and second rails (RL1, RL2) that extend along a second direction (DR2). By placing the stage (STA) on the first and second rails (RL1, RL2) and moving back and forth in the second direction (DR2), a printing process can be performed over the entire area of ​​a target substrate (SUB).

[0131] The target substrate (SUBB) described in this specification is a workpiece for an inkjet printing device (1000) according to one embodiment, and any type of substrate may be applied, such as an inorganic light-emitting display device including an inorganic light-emitting diode including an inorganic semiconductor, an organic light-emitting display device including an organic light-emitting diode including an organic light-emitting layer, a micro light-emitting diode display device including a micro LED, or a quantum dot light-emitting display device using a quantum dot light-emitting diode including a quantum dot light-emitting layer. The target substrate (SUBB) described below is exemplified as an inorganic light-emitting display substrate including an inorganic light-emitting diode as described above with reference to FIGS. 1 to 5, but is not limited thereto, and may be applied to other display devices if the same technical concept is applicable.

[0132] The print head unit (100) can perform the function of printing ink (90) on a target substrate (SUBB). The print head unit (100) can spray a predetermined ink (90) onto the target substrate (SUBB) when the inkjet printing device (1000) is operated. The print head unit (100) can spray ink (90) supplied from an ink supply unit onto the target substrate (SUBB) provided on the sub-stage (7100).

[0133] The ink (90) sprayed from the print head unit (100) may be in a solution state or a colloid state. The ink (90) may include a solvent (91, see FIG. 9) and a plurality of particles (95, see FIG. 9) dispersed within the solvent (91). For example, the solvent (91) is acetone, water, alcohol, toluene, propylene glycol (PG) or propylene glycol methyl acetate (PGMA), triethylene glycol monobutyl ether (TGBE), diethylene glycol monophenyl ether (DGPE), amide solvent, dicarbonyl solvent, diethylene glycol dibenzoate, tricarbonyl solvent, triethyl citrate, phthalate solvent, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl) isophthalate, ethylphthalyl ethyl The particles (95) may be glycolate (ethyl phthalyl ethyl glycolate), but are not limited thereto. A plurality of particles (95) are contained in a dispersed state within a solvent (91) and are supplied to a print head unit (100) through an ink supply unit, and may be sprayed through the print head unit (100). The particles (95) may be inorganic light-emitting diodes made of the inorganic material described above with reference to FIG. 4, but are not limited thereto.

[0134] The print head unit (100) is positioned on top of the probe device (7000) or the stage (STA). The print head unit (100) is mounted on a base frame (6000) and can move. The base frame (6000) may include a first support (610) and a second moving unit (630).

[0135] The print head unit (100) may be mounted on a second moving unit (630) positioned on a first support (610). The manner in which the print head unit (100) is mounted on the second moving unit (630) is not particularly limited. For example, the print head unit (100) may be placed directly on the second moving unit (630), or it may be mounted or coupled to the second moving unit (630) through a separate coupling member.

[0136] The first support (610) may include a first horizontal support (611) extended in a first direction (DR1) which is horizontal, and a first vertical support (612) connected to the first horizontal support (611) and extended in a third direction (DR3) which is vertical. The extension direction of the first horizontal support (611) may be the same as the first direction (DR1) which is perpendicular to the second direction (DR2), which is the direction of movement of the stage (STA) on the first and second rails (RL1, RL2) in a plane. The print head unit (100) may be mounted on a second moving unit (630) disposed on the first horizontal support (611).

[0137] The second moving unit (630) can move along one direction on the first horizontal support (611). The second moving unit (630) may include a moving part (631) and a fixed part (632).

[0138] The moving part (631) of the second moving unit (630) can move along the first direction (DR1) on the first horizontal support part (611), and the print head unit (100) can be fixed to the fixed part (632) of the second moving unit (630) and move along the first direction (DR1) together with the second moving unit (630). The stage (STA) reciprocates in the second direction (DR2) through the first and second rails (RL1, RL2), and the print head unit (100) reciprocates in the first direction (DR1) through the second moving unit (630), so that ink (90) can be sprayed over the entire area of ​​the target substrate (SUBB) even with the print head unit (100), which has an area smaller than that of the target substrate (SUBB).

[0139] In the drawing, the stage (STA) is shown moving along the second direction (DR2) on the first and second rails (RL1, RL2) and the print head unit (100) is shown moving along the first direction (DR1), but is not limited thereto. For example, an inkjet printing device (1000) according to some other embodiments may further include a horizontal moving part that moves the print head unit (100) in the second direction (DR2). In this case, the first and second rails (RL1, RL2) that move the stage (STA) in the second direction (DR2) may be omitted. That is, the stage (STA) may be fixed, and the print head unit (100) may perform a printing process over the entire area of ​​the target substrate (SUBB) while reciprocating along the first direction (DR1) and the second direction (DR2) on the stage (STA). That is, the relative position between the stage (STA) and the print head unit (100) may be adjusted while the stage (STA) is fixed and the print head unit (100) moves along the first and second directions (DR1, DR2) which are horizontal, or it may be adjusted while the print head unit (100) is fixed and the stage (STA) moves along the first and second directions (DR1, DR2) which are horizontal.

[0140] Hereinafter, the drawings illustrate and describe, by way of example, that the stage (STA) moves back and forth along the second direction (DR2) using the first moving unit including the first and second rails (RL1, RL2), and the print head unit (100) moves back and forth along the second direction (DR2) using the second moving unit (630), but it is obvious that the method of adjusting the relative positions of the stage (STA) and the print head unit (100) is not limited thereto.

[0141] The print head unit (100) can be mounted on a second moving unit (630) placed on a first support (610) and spaced apart from the stage (STA) in a third direction (DR3) by a predetermined distance. The distance between the print head unit (100) and the stage (STA) in the third direction (DR3) can be adjusted by the height of the first vertical support (612) of the first support (610). The distance between the print head unit (100) and the stage unit (STAS) can be adjusted within a range where the print head unit (100) has a certain distance from the target substrate (SUB) when the target substrate (SUB) is placed on the stage (STA), thereby securing the space required for the printing process.

[0142] The print head unit (100) may include a first base portion (1100) and a plurality of inkjet heads (300) located on the lower surface of the first base portion (1100).

[0143] The first base portion (1100) may have a shape that extends along one direction. For example, the extension direction of the first base portion (1100) may be the same as the extension direction of the first horizontal support portion (611). As illustrated in the drawing, the first base portion (1100) may include a long side extended in the first direction (DR1) and a short side extended in the second direction (DR2). However, the shape of the first base portion (1100) is not limited thereto.

[0144] A plurality of inkjet heads (300) may be disposed on one side, for example, the lower side, of the first base portion (1100). The plurality of inkjet heads (300) may be disposed spaced apart from each other. The plurality of inkjet heads (300) may be disposed in one direction and arranged in one column or multiple columns.

[0145] In the drawing, a plurality of inkjet heads (300) are shown arranged in two rows, with the inkjet heads (300) in each row arranged staggered from each other, but this is not limited thereto. For example, the inkjet heads (300) may be arranged in a larger number of rows, and the inkjet heads (300) placed in each row may be arranged overlappingly without staggering from each other. In an exemplary embodiment, the number of inkjet heads (300) placed in one print head unit (100) may be 128 to 1800, but is not limited thereto. The planar shape of the inkjet heads (300) is not particularly limited, but may have a rectangular shape as an example.

[0146] FIG. 9 is a schematic cross-sectional view of an inkjet head according to one embodiment.

[0147] Referring to FIGS. 8 and 9, an inkjet head (300) according to one embodiment may include a head base (310), an inner tube (330), a plurality of nozzles (350), and an electric field forming unit (IU). The inkjet head (300) may further include a piezoelectric element (390) and a guide plate (MP).

[0148] The head base (310) may be a part that constitutes the main body of the inkjet head (300). The head base (310) may have a shape that extends along one direction. The extension direction of the head base (310) may be the same as the extension direction of the first horizontal support (611) of the first support (610).

[0149] The inkjet head (300) may include an ink transfer section (AA), an ejection section (DA), and a filter section (FA).

[0150] The ink transfer section (AA) may be a part that receives ink (90) from the first base section (1100) of the inkjet head (300) and transfers it to the discharge section (DA), or transfers the ink (90) that has not been discharged from the discharge section (DA) back to the first base section (1100). That is, the ink transfer section (AA) may be an area positioned between the first base section (1100) and the discharge section (DA) of the head base (310) to provide a passage for the ink (90) to move and to circulate residual ink (90).

[0151] The inner tube (330) may be placed in the ink transfer section (AA). The inner tube (330) may be formed along the extension direction of the head base (310). The inner tube (330) may be placed within the head base (310) and connected to the internal flow path of the first base section (1100). Ink (90) supplied through the first base section (1100) may be introduced through the inlet (331) of the inner tube (330) and flow along the inner tube (330). A portion of the ink (90) flowing along the inner tube (330) may pass through the filter section (FA) and be ejected through the nozzle (350) of the discharge section (DA), and another portion of the ink (90) flowing along the inner tube (330) may exit to the first base section (1110) through the outlet (333) of the inner tube (330). That is, the inner tube (330) can function to move ink (90) provided from the inner flow path of the first base section (1100) to the discharge section (DA), or to recover ink (90) that is not discharged from the discharge section (DA) back into the inner flow path of the first base section (1100). The inlet (331) of the inner tube (330) is located at one end of the inner tube (330), and the outlet (333) of the inner tube (330) can be located on the opposite side (or the other end) of the inlet (331) of the inner tube (330).

[0152] The discharge section (DA) may be a part of the inkjet head (300) from which ink (90) is discharged. A plurality of nozzles (350), a piezo chamber (360), and a piezoelectric element (390) may be disposed in the discharge section (DA).

[0153] A plurality of nozzles (350) may be disposed in a discharge section (DA) located on one side of the head base (310), for example, the bottom side. The plurality of nozzles (350) may be spaced apart from each other and arranged along the extension direction of the head base (310), and may be connected to a filter section (FA) of the head base (310) through a piezo chamber (360) that penetrates the head base (310) located in the discharge section (DA).

[0154] The nozzle (350) can discharge ink (90) that has flowed into the piezo chamber (360) by passing through the filter section (FA) along the inner tube (330). The amount of ink (90) ejected through each nozzle (350) can be controlled according to the voltage applied to the piezoelectric element (390) placed within the piezo chamber (360) of the individual nozzle (350). The pressure generated according to the voltage applied to the piezoelectric element (390) placed in the individual nozzle (350) is applied to the ink (90) in the area surrounding the nozzle (350), and the ink (90) can be ejected through the nozzle (350). For example, in non-spraying mode, the piezoelectric element (390) of the inkjet head (350) is adjusted so that the internal pressure of the piezo chamber (360) and the external pressure of the inkjet head (300) are in equilibrium, so that ink (90) is not sprayed through the nozzle (350). In spraying mode, the piezoelectric element (390) of the inkjet head (300) is adjusted so that the internal pressure of the piezo chamber (360) is greater than the external pressure of the inkjet head (300), so that ink (90) can be sprayed through the nozzle (350).

[0155] The piezo chamber (360) may be positioned between the nozzle (350) and the filter section (FA) and may be a place where ink (90) is temporarily stored before being discharged through the nozzle (350). When pressure by the piezoelectric element (390) is applied to the ink (90) located within the piezo chamber (360), the ink (90) may be discharged through the nozzle (350). The piezo chamber (360) is connected to the lower part of the inner tube (330) and may be positioned to correspond to each of the multiple nozzles (350).

[0156] The filter section (FA) may be positioned between the ink transfer section (AA) and the discharge section (DA). Specifically, the filter section (FA) may be positioned between the inner tube (330) and the piezo chamber (360). The filter section (FA) may be a part that removes impurities in the ink (90) flowing from the ink transfer section (AA) to the nozzle (350) or guides the flow of the ink (90). Additionally, the filter section (FA) may be a part that generates the flow of the ink (90) in non-spray mode to prevent particles (95) dispersed in the ink (90) remaining in the inkjet head (300) in non-spray mode from settling.

[0157] A first filter (FT1) may be disposed in the filter section (FA). A guide plate (MP) may be further disposed in the filter section (FA).

[0158] The first filter (FT1) may be placed between the inner tube (330) and the piezo chamber (360). The first filter (FT1) includes a plurality of holes and selectively allows particles (95) within the ink (90) to pass through, while blocking other substances (or foreign substances) other than the particles (95) within the ink (90). That is, the first filter (FT1) can serve to prevent other substances (or foreign substances) other than the particles (95) from entering the discharge section (DA) when the ink (90) flowing along the inner tube (330) enters the piezo chamber (360) of the discharge section (DA). Accordingly, it is possible to prevent the nozzle (350) from being clogged by foreign substances or the foreign substances from being mixed into the ink (90) discharged through the nozzle (350).

[0159] As described above, the inkjet head (300) may include an electric field forming unit (IU). The electric field forming unit (IU) may include an electric field forming electrode (320) and a voltage application device (340). The electric field forming unit (IU) may form an electric field within the inkjet head (300) to induce the flow of ink (90).

[0160] The electric field forming electrode (320) can be placed in the filter section (FA). The electric field forming electrode (320) can be placed in the filter section (FA) to form an electric field according to an electric signal received from the voltage application device (340).

[0161] In one embodiment, the electric field forming electrode (320) may constitute a first filter (FT1). The electric field forming electrode (320) may include a first electric field forming electrode (321) and a second electric field forming electrode (322). The first electric field forming electrode (321) and the second electric field forming electrode (322) may constitute a first filter (FT1). In this embodiment, the first electric field forming electrode (321) may be a first electrode filter (321), and the second electric field forming electrode (322) may be a second electrode filter (322). Hereinafter, for convenience of explanation, the first electric field forming electrode (321) may be referred to as the first electrode filter (321), and the second electric field forming electrode (322) may be referred to as the second electrode filter (322).

[0162] The first electric field forming electrode (321) may be positioned above the discharge section (DA). The second electric field forming electrode (322) may be positioned above the first electric field forming electrode (321) and spaced apart from the first electric field forming electrode (321) in the third direction (DR3). The second electric field forming electrode (322) may be positioned overlappingly with the first electric field forming electrode (321) in the third direction (DR3).

[0163] The first electric field forming electrode (321) may include a plurality of first holes (HA1). The second electric field forming electrode (322) may include a plurality of second holes (HA2). Particles (95) in the ink (90) may pass through the first holes (HA1) and the second holes (HA2).

[0164] The first electric field forming electrode (321) and the second electric field forming electrode (322) can receive an electric signal from the voltage application device (340). When an electric signal is applied to the first electric field forming electrode (321) and the second electric field forming electrode (322) respectively from the voltage application device (340), an electric field can be formed between the first electric field forming electrode (321) and the second electric field forming electrode (322).

[0165] A guide plate (MP) can be positioned between the first filter (FT1) and the piezo chamber (360). That is, the guide plate (MP) can be positioned below the first filter (FT1) within the filter section (FA). The guide plate (MP) can serve to guide the flow of ink (90) so that the amount of ink (90) flowing into each of the plurality of piezo chambers (360) is uniform.

[0166] FIG. 10 is a plan view of the first and second electric field generating electrodes according to one embodiment. FIG. 11 is a schematic cross-sectional view for comparing the size between the holes and particles of the first and second electric field generating electrodes according to one embodiment.

[0167] Referring to FIGS. 10 and 11, the first electric field forming electrode (321) and the second electric field forming electrode (322) may overlap each other in a third direction (DR3). The planar shapes of the first electric field forming electrode (321) and the second electric field forming electrode (322) may be identical to each other. That is, the first electric field forming electrode (321) and the second electric field forming electrode (322) overlap each other and may have the same planar shape. For example, the first electric field forming electrode (321) and the second electric field forming electrode (322) may have a planar mesh shape.

[0168] The first electric field forming electrode (321) may include a plurality of first holes (HA1) penetrating the first electric field forming electrode (321). The plurality of first holes (HA1) may be spaced apart from each other. The plurality of first holes (HA1) may be arranged in a planar rectangular matrix shape.

[0169] The second electric field forming electrode (322) may include a plurality of second holes (HA2) penetrating the second electric field forming electrode (322). The plurality of second holes (HA2) may be spaced apart from each other. The plurality of second holes (HA2) may be arranged in a planar rectangular matrix shape.

[0170] The planar shape of the first hole (HA1) and the planar shape of the second hole (HA2) may be identical to each other. Accordingly, the first width (W1) of the first hole (HA1) in the first direction (DR1) and the second width (W2) of the second hole (HA2) in the first direction (DR1) may be identical to each other. Meanwhile, although the planar shapes of the plurality of first holes (HA1) and the plurality of second holes (HA2) are depicted as square in the drawings, they are not limited thereto. For example, the planar shapes of the plurality of first holes (HA1) and the plurality of second holes (HA2) may be circular. The plurality of first holes (HA1) and the plurality of second holes (HA2) may overlap in the third direction (DR3).

[0171] As described above, the first electric field forming electrode (321) and the second electric field forming electrode (322) can constitute the first filter (FT1). Accordingly, for a particle (95) in the ink (90) to pass through the first filter (FT1) (specifically, the first electric field forming electrode (321) and the second electric field forming electrode (322)), the length (h) of the particle (95) may be smaller than the first width (W1) of the first hole (HA1) and the second width (W2) of the second hole (HA2). Accordingly, the particle (95) in the ink (90) can pass through the first electric field forming electrode (321) and the second electric field forming electrode (322) constituting the first filter (FT1).

[0172] FIGS. 12 and FIGS. 13 are schematic cross-sectional views illustrating the operation of an inkjet head according to one embodiment. FIG. 14 is an enlarged view showing an example of region B of FIG. 12 enlarged.

[0173] FIG. 12 is a diagram showing the operation of an inkjet head (300) in a spray mode, and FIG. 13 is a diagram showing the operation of an inkjet head (300) in a non-spray mode. Specifically, the spray mode is a mode in which ink (90) is supplied from outside the inkjet head (300) and the ink (90) is discharged through a plurality of nozzles (350), and the non-spray mode may be a mode in which ink (90) is not supplied from outside the inkjet head (300) and the ink (90) is not discharged through the plurality of nozzles (350). As described above, in the non-spray mode, the piezoelectric element (390) is adjusted so that the internal pressure and the external pressure of the inkjet head (300) are in equilibrium, so that the ink (90) is not sprayed through the nozzles (350). Additionally, in the spraying mode, the piezoelectric element (390) is adjusted so that the internal pressure of the inkjet head (300) is greater than the external pressure, allowing ink (90) to be sprayed through the nozzle (350).

[0174] Referring to FIG. 12, in the spraying mode, ink (90) can be supplied from the outside of the inkjet head (300) to the inside of the inkjet head (300) through the inlet (331) of the inner tube (330). The ink (90) can flow along the inner tube (330) in a direction from the inlet (331) of the inner tube (330) toward the outlet (333). A portion of the ink (90) flowing along the inner tube (330) can pass through the electric field forming electrode (320) constituting the first filter (FT1) and flow into the filter section (FA), and another portion of the ink (90) flowing along the inner tube (330) can be recovered to the outside of the inkjet head (300) through the outlet (333) of the inner tube (330).

[0175] Ink (90), from which foreign substances have been removed by passing through the electric field forming electrode (320) constituting the first filter (FT1), can be uniformly introduced into a plurality of piezo chambers (360) by the guide plate (MP). The ink (90) introduced into the piezo chambers (360) can be discharged from the piezo chambers (360) to the outside of the inkjet head (300) through each nozzle (350) by hydraulic pressure formed by the piezoelectric element (390).

[0176] Meanwhile, in the spraying mode, the voltage application device (340) may not transmit an electric signal to the first electric field forming electrode (321) and the second electric field forming electrode (322), respectively. Therefore, in the spraying mode, an electric field may not be formed between the first electric field forming electrode (321) and the second electric field forming electrode (322). That is, in the spraying mode, the first electric field forming electrode (321) and the second electric field forming electrode (322) may function as a filter (electrode filter) that blocks foreign substances in the ink (90), but may not function to form an electric field in the ink (90).

[0177] Referring to FIGS. 13 and 14, in non-spray mode, ink (90) may not be supplied from the outside of the inkjet head (300) into the inside of the inkjet head (300). Therefore, in non-spray mode, ink (90) may not flow along the inner tube (330) located above the filter section (FA). Meanwhile, if no flow occurs in the ink (90) remaining inside the inkjet head (300) in non-spray mode, particles (95) dispersed within the ink (90) may settle or settle within the ink (90), including a substance with a relatively higher specific gravity than the solvent (91). In this case, a plurality of particles (95) may settle or settle from the inside of the inkjet head (300) into the piezo chamber (360) located at the bottom of the inkjet head (300), and clogging of the nozzle (350) may occur due to the plurality of particles (95) remaining. The electric field forming unit (IU) according to the present embodiment can generate a flow of ink (90) inside the inkjet head (300) (specifically, the filter part (FA)) in a non-spraying mode, thereby preventing particles (95) in the remaining ink (90) from settling or settling into the piezo chamber (360) and preventing the nozzle (350) from becoming clogged.

[0178] Specifically, in non-spray mode, the electric field forming unit (IU) can form an electric field (IEL) within the inkjet head (300). The voltage application device (340) can apply a first electric signal (SG1) and a second electric signal (SG2) to the first electric field forming electrode (321) and the second electric field forming electrode (322), respectively, which constitute the first filter (FT1). In an exemplary embodiment, the first electric signal (SG1) may be an electric signal that applies a ground voltage to the first electric field forming electrode (321), and the second electric signal (SG2) may be an electric signal that applies an alternating voltage to the second electric field forming electrode (322), but is not limited thereto. For example, in some other embodiments, the second electric signal (SG2) is an electric signal that applies an alternating voltage to the second electric field forming electrode (322), but the first electric signal (SG1) applied to the first electric field forming electrode (321) may not be an electric signal that applies a ground voltage to the first electric field forming electrode (321). In some other embodiments, the first electric signal (SG1) is an electric signal that applies an alternating voltage to the first electric field forming electrode (321), and the second electric signal (SG2) may be an electric signal that applies a ground voltage to the second electric field forming electrode (322).

[0179] When a first electric signal (SG1) is applied to the first electric field forming electrode (321) and a second electric signal (SG2) is applied to the second electric field forming electrode (322), an electric field (IEL) may be formed between the first electric field forming electrode (321) and the second electric field forming electrode (322). The electric field (IEL) may be generally parallel to the direction in which the first electric field forming electrode (321) and the second electric field forming electrode (322) are spaced apart from each other. Due to the electric field (IEL) formed between the first electric field forming electrode (321) and the second electric field forming electrode (322), flow (AF) may occur in the ink (90) located between the first electric field forming electrode (321) and the second electric field forming electrode (322). In non-spray mode, flow (AF) of the ink (90) located between the first electric field forming electrode (321) and the second electric field forming electrode (322) can cause flow not only to the ink (90) located between the first electric field forming electrode (321) and the second electric field forming electrode (322), but also to the ink (90) remaining in other areas inside the inkjet head (300). Accordingly, particles (95) within the ink (90) can be moved together with the ink (90) by the flow of the ink (90). Therefore, even when the inflow of ink (90) is blocked in non-spray mode, flow is caused to the ink (90) remaining in the inkjet head (300) by the electric field forming unit (IU), thereby preventing particles (95) within the remaining ink (90) from settling or sinking into the piezo chamber (360) and preventing the nozzle (350) from becoming clogged. In addition, in non-spray mode, the ink (90) is circulated inside the inkjet head (300) by the flow (AF) of the ink (90), so that bubbles that may occur inside the inkjet head (300) can also be removed.

[0180] Meanwhile, in non-spray mode, the electric field forming unit (IU) transmits a first electric signal (SG1) and a second electric signal (SG2) to the first electric field forming electrode (321) and the second electric field forming electrode (322), respectively, to form an electric field (IEL) between the first electric field forming electrode (321) and the second electric field forming electrode (322), thereby generating a flow (AF) of the ink (90) remaining in the inkjet head (300), and at the same time, it can also function as a filter (electrode filter) that blocks foreign substances in the ink (90) from entering the filter section (FA) from the inner tube (330) by the flow (AF) of the ink (90) formed by the electric field forming unit (IU).

[0181] FIG. 15 is a schematic cross-sectional view of an inkjet head according to another embodiment.

[0182] Referring to FIG. 15, the inkjet head (300_1) according to the present embodiment differs from the inkjet head (300) of FIG. 9 in that the electric field forming electrode (320_1) disposed in the filter section (FA_1) is disposed between the guide plate (MP) and the discharge section (DA) to form a second filter (FT2), but does not form a first filter (FT1_1).

[0183] Specifically, the inkjet head (300_1) according to the present embodiment may include a first filter (FT1_1) and a second filter (FT2) disposed in a filter section (FA_1).

[0184] The first filter (FT1_1) can be positioned on the upper part of the guide plate (MP) in the filter section (FA_1). Specifically, the first filter (FT1_1) can be positioned between the guide plate (MP) and the inner tube (330). The first filter (FT1_1) includes a plurality of holes and can serve to block foreign substances within the ink (90) flowing from the inner tube (330) into the filter section (FA_1). The first filter (FT1_1) can be composed of a single plate.

[0185] The second filter (FT2) can be positioned below the guide plate (MP) in the filter section (FA_1). Specifically, the second filter (FT2) can be positioned between the guide plate (MP) and the piezo chamber (360) positioned in the discharge section (DA).

[0186] In this embodiment, the electric field forming electrode (320_1) of the electric field forming unit (IU_1) can form a second filter (FT2). That is, the first electric field forming electrode (321_1) is positioned between the guide plate (MP) and the piezo chamber (360), and the second electric field forming electrode (322_1) can be positioned between the guide plate (MP) and the first electric field forming electrode (321_1). The electric field forming electrode (320_1) according to this embodiment has the same function and shape as the electric field forming electrode (320) of FIG. 9 described above, except that it forms a second filter (FT2) at the bottom of the guide plate (MP), so a redundant description will be omitted.

[0187] The electric field forming electrode (320_1) according to the present embodiment is positioned adjacent to the discharge section (DA) between the guide plate (MP) and the discharge section (DA), so that the flow of ink (90) remaining in the piezo chamber (360) can be effectively generated in non-spray mode. Accordingly, particles (95) within the ink (90) can be more efficiently prevented from settling or settling at the bottom of the piezo chamber (360), thereby more efficiently preventing clogging of the nozzle (350).

[0188] FIG. 16 is a schematic cross-sectional view of an inkjet head according to another embodiment.

[0189] Referring to FIG. 16, the inkjet head (300_2) according to the present embodiment differs from the inkjet head (300_1) of FIG. 15 in that the electric field forming electrode (320_2) disposed in the filter section (FA_2) constitutes the guide plate (MP_2).

[0190] Specifically, the electric field forming electrode (320_2) of the electric field forming unit (IU_2) according to the present embodiment may form a guide plate (MP_2). The electric field forming electrode (320_2) of the electric field forming unit (IU_2) that forms the guide plate (MP_2) may be positioned between the first filter (FT1_1) and the discharge unit (DA). That is, the first electric field forming electrode (321_2) may be positioned between the first filter (FT1_1) and the piezo chamber (360), and the second electric field forming electrode (322_2) may be positioned between the first filter (FT1_1) and the first electric field forming electrode (321_2).

[0191] The first electric field forming electrode (321_2) and the second electric field forming electrode (322_2) may not have multiple holes formed therein. That is, the first electric field forming electrode (321_2) and the second electric field forming electrode (322_2) may each be an electrode plate that does not include multiple holes.

[0192] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing the technical concept or essential features thereof. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. Explanation of the symbols

[0193] 1000: Inkjet printing device STA: Stage 100: Print head unit 300: Inkjet head 310: Head Base 330: Internal Affairs 320: Electric field forming electrode 321: First electric field forming electrode 322: Second electric field forming electrode 340: Voltage application device 350: Nozzle 360: Piezo Chamber 90: Ink 95: Particle IEL: Electric field ED: Light-emitting element 200: Electrode layer 210: First electrode 220: Second electrode

Claims

Claim 1 An inkjet printing device comprising: a stage on which a target substrate is placed; and an inkjet head located above the stage, wherein the inkjet head comprises: a discharge section having a plurality of nozzles for spraying ink containing a plurality of particles; a filter section disposed above the discharge section and selectively passing the plurality of particles; and an electric field forming electrode disposed above the filter section and forming an electric field in the filter section, wherein the electric field forming electrode comprises a first electric field forming electrode and a second electric field forming electrode spaced apart from each other, and the second electric field forming electrode is disposed overlappingly with the first electric field forming electrode above the first electric field forming electrode. Claim 2 delete Claim 3 delete Claim 4 An inkjet printing device according to claim 1, wherein the first electric field forming electrode comprises a plurality of first holes spaced apart from each other, and the second electric field forming electrode comprises a plurality of second holes spaced apart from each other. Claim 5 In claim 4, an inkjet printing device in which the diameter of the first hole and the diameter of the second hole are each larger than the length of the particle. Claim 6 In claim 4, the inkjet printing device wherein the plurality of first holes overlap with the plurality of second holes. Claim 7 An inkjet printing device comprising: a stage on which a target substrate is placed; and an inkjet head located above the stage, wherein the inkjet head comprises: a discharge section having a plurality of nozzles for spraying ink containing a plurality of particles; a filter section disposed above the discharge section and selectively passing the plurality of particles; and an electric field forming electrode disposed in the filter section and forming an electric field in the filter section, wherein the electric field forming electrode comprises a first electric field forming electrode and a second electric field forming electrode spaced apart from each other, and the electric field is formed between the first electric field forming electrode and the second electric field forming electrode. Claim 8 In claim 1, the electric field forming electrode is an inkjet printing device constituting a first filter. Claim 9 An inkjet printing device comprising: a stage on which a target substrate is placed; and an inkjet head located above the stage, wherein the inkjet head comprises: a discharge section having a plurality of nozzles for spraying ink containing a plurality of particles; a filter section disposed above the discharge section and selectively passing the plurality of particles; and an electric field forming electrode disposed in the filter section and forming an electric field in the filter section, wherein the electric field forming electrode constitutes a first filter, and the inkjet head further comprises a guide plate disposed in the filter section. Claim 10 In claim 9, the first filter is an inkjet printing device positioned on the upper part of the guide plate. Claim 11 In claim 9, the first filter is an inkjet printing device disposed at the lower part of the guide plate. Claim 12 In claim 11, the inkjet printing device further comprises a second filter disposed on the upper part of the guide plate, wherein the inkjet head is an inkjet head. Claim 13 In claim 1, the electric field forming electrode is an inkjet printing device constituting a guide plate. Claim 14 An inkjet printing device comprising: a stage on which a target substrate is placed; and an inkjet head located above the stage, wherein the inkjet head comprises: a discharge section having a plurality of nozzles for spraying ink containing a plurality of particles; a filter section disposed above the discharge section and selectively passing the plurality of particles; and an electric field forming electrode disposed in the filter section and forming an electric field in the filter section, and further comprising a piezo chamber disposed in the discharge section and connected to each of the plurality of nozzles. Claim 15 An inkjet printing device according to claim 1, further comprising a voltage application device for applying an electric signal to the electric field forming electrode. Claim 16 An inkjet printing device comprising: a stage on which a target substrate is placed; and an inkjet head located above the stage, wherein the inkjet head comprises: a discharge section having a plurality of nozzles for spraying ink containing a plurality of particles; a filter section disposed above the discharge section and selectively passing the plurality of particles; and an electric field forming electrode disposed in the filter section and forming an electric field in the filter section, and further comprising a voltage applying device for applying an electric signal to the electric field forming electrode, wherein the ink remaining in the inkjet head flows by driving the voltage applying device. Claim 17 In claim 16, the voltage application device is driven in the non-jet mode of the inkjet head, in an inkjet printing device. Claim 18 An inkjet printing device comprising: a stage on which a target substrate is placed; and an inkjet head located above the stage, wherein the inkjet head comprises a plurality of nozzles for spraying ink containing a plurality of particles, a first electrode filter disposed above the plurality of nozzles and comprising a plurality of first holes, and a second electrode filter disposed overlapping with the first electrode filter above the first electrode filter and comprising a plurality of second holes, wherein an electric field is formed between the first electrode filter and the second electrode filter in a non-spraying mode of the inkjet head. Claim 19 delete Claim 20 In claim 18, an inkjet printing device in which the diameter of the plurality of first holes and the diameter of the plurality of second holes are larger than the length of the particle.

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