Inkjet printing apparatus and method for solving not ejected of the same

Abstract

The present invention relates to an inkjet printing device and a method for resolving non-discharge thereof. An inkjet printing device according to one embodiment includes a print head unit comprising a plurality of nozzles for discharging ink including a plurality of light-emitting elements, a dipping bath in which the print head unit is immersed and which contains a suction solution, and a suction unit connected to the print head unit and which sucks in the suction solution to suck in the ink remaining in the print head unit.

Description

Technology Field

[0001] The present invention relates to an inkjet printing device and a method for resolving non-discharge thereof. 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 fluorescent materials and inorganic light-emitting diodes that use inorganic materials as fluorescent materials.

[0004] Meanwhile, an inkjet printing device may be used to form an organic layer included in a display device or to form 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 and a method for solving the non-emission caused by light-emitting elements remaining in the inkjet head.

[0006] The problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems 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 may include a print head unit comprising a plurality of nozzles for discharging ink including a plurality of light-emitting elements, a dipping bath in which the print head unit is immersed and which contains a suction solution, and a suction unit connected to the print head unit and which sucks in the suction solution to suck in the ink remaining in the print head unit.

[0008] It may further include a first connecting pipe connected to one end of the print head unit to supply the ink to the print head unit, a second connecting pipe connected to the other end of the print head unit to move the ink from the print head unit, a first valve disposed in the first connecting pipe to regulate the supply of the ink, and a second valve disposed in the second connecting pipe to regulate the flow rate of the ink.

[0009] The suction unit may include a third connecting pipe connected to the second connecting pipe, a suction pump connected to the third connecting pipe to transmit power to the ink, and an ink storage unit connected to the end of the third connecting pipe to store the ink supplied through the suction pump.

[0010] The third connecting pipe is connected to the second connecting pipe through the second valve, and the ink can move to the second connecting pipe or the third connecting pipe depending on the opening and closing of the second valve.

[0011] The second valve mentioned above may be a three-way valve.

[0012] The above-mentioned dipping bath contains the above-mentioned suction solution and may be provided separately from the above-mentioned print head unit.

[0013] The above suction solution may be the ink or a solvent contained in the ink.

[0014] The apparatus further comprises a first circulating ink storage unit in which the ink is stored, a second circulating ink storage unit connected to the second connecting pipe and receiving the ink from the first circulating ink storage unit, a circulation pump that moves the ink from the second circulating ink storage unit, and a third circulating ink storage unit that receives the ink from the circulation pump, wherein the third circulating ink storage unit is connected to the first connecting pipe and can supply ink to the print head unit.

[0015] The above print head unit includes an inkjet head, wherein the inkjet head includes an inlet connected from the first connecting tube, an inner tube passing through the inside of the inkjet head from the inlet, a plurality of piezo chambers connected downward from the inner tube, and an outlet disposed opposite the inlet among the inner tubes and connected to the second connecting tube, and the plurality of nozzles may each be disposed in the plurality of piezo chambers.

[0016] In addition, a method for resolving non-discharge of an inkjet printing device according to one embodiment may include a print head unit comprising a plurality of nozzles for discharging ink including a plurality of light-emitting elements, a dipping bath in which the print head unit is immersed and which contains a suction solution, and a suction unit connected to the print head unit and which sucks in the suction solution to suck in the ink remaining in the print head unit, the method may include the steps of: immersing the print head unit in the dipping bath; closing a first valve connected to one end of the print head unit and switching a second valve connected to the other end; and driving a suction pump of the suction unit connected to the second valve to suck in the suction solution contained in the dipping bath through the print head unit, thereby sucking in the ink remaining in the print head unit together.

[0017] The step of immersing the print head unit in the dipping bath may involve immersing the unit in the suction solution such that a plurality of nozzles of the inkjet head equipped in the print head unit are submerged.

[0018] The inkjet printing device comprises a first connecting pipe connected to one end of the print head unit to supply the ink to the print head unit, and a second connecting pipe connected to the other end of the print head unit to move the ink from the print head unit, wherein the first valve is disposed in the first connecting pipe to regulate the supply of the ink, and the second valve is disposed in the second connecting pipe to regulate the flow rate of the ink.

[0019] The suction unit may include a third connecting pipe connected to the second connecting pipe, a suction pump connected to the third connecting pipe to transmit power to the ink, and an ink storage unit connected to the end of the third connecting pipe to store the ink supplied through the suction pump.

[0020] The step of closing the first valve and switching the second valve is such that the movement of the ink into the first connecting pipe is blocked by closing the first valve, and a movable flow path for the ink can be formed through the second connecting pipe and the third connecting pipe by switching the second valve.

[0021] By driving the suction pump, a suction force is applied through the third connecting pipe, the second valve, the second connecting pipe, and the print head unit connected to the suction pump, thereby allowing the suction solution to be sucked in.

[0022] The above print head unit includes an inkjet head, and the inkjet head includes a piezo chamber and a plurality of nozzles, and can draw the suction solution from the plurality of nozzles.

[0023] The suction solution can form turbulence within the piezo chamber connected to the plurality of nozzles as it is sucked in through the plurality of nozzles.

[0024] The light-emitting element of the ink accumulated in the piezo chamber rises due to the above turbulence, and the ink containing the light-emitting element together with the suction solution can be sucked into the suction part through the second connecting pipe.

[0025] The above ink and the above suction solution can be stored in the suction ink storage unit through the suction pump of the above suction unit.

[0026] After the step of sucking in the suction solution and the ink, the first valve can be opened and the second valve switched to block the movement of the ink to the third connecting pipe.

[0027] Specific details of other embodiments are included in the detailed description and drawings. Effects of the invention

[0028] According to the inkjet printing device and the method for resolving non-ejection thereof according to the embodiments, a suction unit and a dipping bath may be provided. Through this, a suction process is performed to suck a suction solution from the nozzle of the inkjet head, thereby removing light-emitting elements accumulated in the piezo chamber of the inkjet head. Accordingly, stains caused by non-ejection of ink can be improved, thereby enhancing display quality.

[0029] 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

[0030] FIG. 1 is a schematic plan view of a display device according to one embodiment. FIG. 2 is a cross-sectional view schematically showing some subpixels of a display device according to one embodiment. FIG. 3 is a plan view showing one pixel of a display device according to one embodiment. Figure 4 is a cross-sectional view taken along the Q1-Q1' line, Q2-Q2' line and Q3-Q3' line of Figure 3. FIG. 5 is a schematic diagram of a light-emitting element according to one embodiment. FIG. 6 is a schematic perspective view of an inkjet printing device according to one embodiment. FIG. 7 is a schematic bottom 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 diagram showing an ink circulation unit, a suction unit, and a print head unit according to one embodiment. FIG. 10 is a schematic cross-sectional view of an inkjet head according to one embodiment. FIG. 11 is a drawing showing an inkjet printing device according to one embodiment. FIG. 12 is a flowchart illustrating a method for resolving non-ejection of an inkjet printing device according to one embodiment. FIGS. 13 to 16 are drawings showing a step-by-step method for resolving non-ejection of an inkjet printing device according to one embodiment. Figure 17 is a graph showing the discharge state of the nozzle according to Experimental Examples 1 and 2. Figure 18 is an image of the nozzle discharge process taken every 10 microseconds (μs) for 60 microseconds (μs) after the process of condition #4 is finished. Figure 19 is an image of the nozzle discharge process taken every 10 microseconds (μs) for 60 microseconds (μs) after the process of condition #8 is finished. Specific details for implementing the invention

[0031] 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 but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0032] When elements or layers are referred to as being "on" another element or layer, this includes cases where another layer or element is interposed directly on or in the middle of another element. Throughout the specification, the same reference numerals refer to the same components. Shapes, sizes, ratios, angles, numbers, etc., disclosed in the drawings for describing embodiments are exemplary and therefore the invention is not limited to the depicted details.

[0033] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may also be the second component within the technical scope of the present invention.

[0034] The features of each of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each embodiment may be implemented independently of one another or may be implemented together in an associated relationship.

[0035] Specific embodiments will be described below with reference to the attached drawings.

[0036] FIG. 1 is a schematic plan view of a display device according to one embodiment.

[0037] 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, electronic 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).

[0038] 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.

[0039] In the drawing describing the display device (10), 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. The third direction (DR3) is perpendicular to each of the first direction (DR1) and the second direction (DR2). In the embodiment describing the display device (10), the third direction (DR3) represents the thickness direction of the display device (10).

[0040] The shape of the display device (10) can be varied in many ways. For example, the display device (10) may have a rectangular shape in which the first direction (DR1) in the plane includes a longer side than the second direction (DR2). As another example, the display device (10) may have a rectangular shape in which the second direction (DR2) in the plane includes a longer side than the first direction (DR1). However, it is not limited thereto and may have a shape such as a square, a square with rounded corners (vertices), other polygons, a circle, etc. The shape of the display area (DPA) of the display device (10) may also be similar to the overall shape of the display device (10). In FIG. 1, a display device (10) and a display area (DPA) having a rectangular shape in which the first direction (DR1) is longer than the second direction (DR2) are illustrated.

[0041] The display device (10) may include a display area (DPA) and a non-display area (NDA). The display area (DPA) is an area where the screen can be displayed, and the non-display area (NDA) is an area where the screen is not displayed. The display area (DPA) may also be referred to as an active area, and the non-display area (NDA) as an inactive area. The display area (DPA) may generally occupy the center of the display device (10).

[0042] The 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, but is not limited thereto, and may be a rhombus shape with each side tilted toward one direction. Each pixel (PX) may be arranged alternately in a stripe type or a pentile type. Additionally, each of the pixels (PX) may include one or more light-emitting elements (30) that emit light of a specific wavelength range to display a specific color.

[0043] 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 display area (DPA) is rectangular in shape, and the non-display area (NDA) may be placed adjacent to the four sides of the display area (DPA). The non-display area (NDA) may form the bezel of the display device (10). In each non-display area (NDA), wiring or circuit drivers included in the display device (10) may be placed, or external devices may be mounted.

[0044] FIG. 2 is a cross-sectional view schematically showing some subpixels of a display device according to one embodiment.

[0045] Referring to FIG. 2, the display area (DPA) of the display device (10) may include first to third light-emitting areas (LA1, LA2, LA3). Each of the first to third light-emitting areas (LA1, LA2, LA3) may be an area where light generated from a light-emitting element (30) of the display device (10) is emitted to the outside of the display device (10).

[0046] The display device (10) may include a substrate (11), a buffer layer (12), a transistor layer (TFTL), a light-emitting element layer (EML), a wavelength conversion layer (WLCL), a color filter layer (CFL), and an encapsulation layer (TFE).

[0047] The substrate (11) may be a base substrate or a base member and may be made of an insulating material such as a polymer resin. For example, the substrate (11) may be a flexible substrate capable of bending, folding, rolling, etc. The substrate (11) may include polyimide (PI), but is not limited thereto.

[0048] The buffer layer (12) may be disposed on the substrate (11). The buffer layer (12) may be made of an inorganic film capable of preventing the penetration of air or moisture. For example, the buffer layer (12) may include a plurality of inorganic films stacked alternately.

[0049] A transistor layer (TFTL) may be disposed on the buffer layer (12). The transistor layer (TFTL) may include a first transistor (T1), a first gate insulating layer (13), a first interlayer insulating layer (15), a second interlayer insulating layer (17), and a first flattening layer (19).

[0050] The first transistor (T1) may be placed on the buffer layer (BF) and may constitute a pixel circuit for each of a plurality of pixels. For example, the first transistor (T1) may be a driving transistor or a switching transistor of a pixel circuit. The first transistor (T1) may include an active layer (ACT), a gate electrode (G1), a source electrode (SE), and a drain electrode (DE). The active layer (ACT) may include a plurality of conductive regions (ACTa, ACTb) and a channel region (ACTc) between them.

[0051] A light-emitting element layer (EML) may be disposed on a transistor layer (TFTL). The light-emitting element layer (EML) may include a first pattern (BNL1), a light-emitting element (30), and a second pattern (BNL2). The light-emitting element (30) may be disposed on the first transistor (T1). The light-emitting element (30) may be disposed between the first electrode and the second electrode and connected to the first connecting electrode and the second connecting electrode, respectively.

[0052] A detailed description of the aforementioned transistor layer (TFTL) and light-emitting element layer (EML) will be provided later with reference to FIGS. 3 to 5.

[0053] A second flattening layer (41) may be disposed on the light-emitting element layer (EML) to flatten the top of the light-emitting element layer (EML). The second flattening layer (41) may include an organic material. For example, the second flattening layer (41) may include at least one of acrylic resin, epoxy resin, phenolic resin, polyamide resin, and polyimide resin.

[0054] The wavelength conversion layer (WLCL) may include a first capping layer (CAP1), a first light-blocking member (BK1), a first wavelength conversion unit (WLC1), a second wavelength conversion unit (WLC2), a light-transmitting unit (LTU), a second capping layer (CAP2), and a third flattening layer (43).

[0055] The first capping layer (CAP1) may be disposed on the second planarization layer (41) of the light-emitting element layer (EML). The first capping layer (CAP1) may seal the lower surface of the first and second wavelength conversion units (WLC1, WLC2) and the light transmission unit (LTU). The first capping layer (CAP1) may include an inorganic material. For example, the first capping layer (CAP1) may include at least one of silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, and silicon oxynitride.

[0056] The first light-blocking member (BK1) may be placed in the first to third light-blocking regions (BA1, BA2, BA3) on the first capping layer (CAP1). The first light-blocking member (BK1) may overlap with the second pattern (BNL2) in the thickness direction. The first light-blocking member (BK1) can block the transmission of light. The first light-blocking member (BK1) can improve color reproduction by preventing light from interfering and mixing between the first to third light-emitting regions (LA1, LA2, LA3). The first light-blocking member (BK1) may be arranged in a grid shape surrounding the first to third light-emitting regions (LA1, LA2, LA3) on a plane.

[0057] The first light-blocking member (BK1) may include an organic light-blocking material and a liquid-repellent component. Here, the liquid-repellent component may be composed of a fluorine-containing monomer or a fluorine-containing polymer, and specifically may include a fluorine-containing aliphatic polycarbonate. For example, the first light-blocking member (BK1) may be composed of a black organic material containing the liquid-repellent component. The first light-blocking member (BK1) may be formed through a coating and exposure process, etc., of an organic light-blocking material containing the liquid-repellent component.

[0058] The first light-blocking member (BK1) can separate the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU) into corresponding light-emitting regions (LA) by including a liquid-repellent component. For example, if the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU) are formed by an inkjet method, an ink composition may flow on the upper surface of the first light-blocking member (BK1). In this case, the first light-blocking member (BK1) can induce the ink composition to flow into each light-emitting region by including a liquid-repellent component. Therefore, the first light-blocking member (BK1) can prevent the ink composition from mixing.

[0059] A first wavelength conversion unit (WLC1) may be disposed in a first light-emitting region (LA1) on a first capping layer (CAP1). The first wavelength conversion unit (WLC1) may be surrounded by a first light-blocking member (BK1). The first wavelength conversion unit (WLC1) may include a first base resin (BS1), a first scatterer (SCT1), and a first wavelength shifter (WLS1).

[0060] The first base resin (BS1) may include a material with a relatively high light transmittance. The first base resin (BS1) may be made of a transparent organic material. For example, the first base resin (BS1) may include at least one of organic materials such as an epoxy resin, an acrylic resin, a cardo resin, and an imide resin.

[0061] The first scatterer (SCT1) may have a refractive index different from that of the first base resin (BS1) and may form an optical interface with the first base resin (BS1). For example, the first scatterer (SCT1) may include a light-scattering material or light-scattering particles that scatter at least a portion of the transmitted light. For example, the first scatterer (SCT1) may include metal oxide particles such as titanium oxide (TiO2), zirconium oxide (ZrO2), aluminum oxide (AlxOy), indium oxide (In2O3), zinc oxide (ZnO), or tin oxide (SnO2), or organic particles such as acrylic resin or urethane resin. The first scatterer (SCT1) may scatter light in a random direction regardless of the incident direction of the incident light without substantially changing the peak wavelength of the incident light.

[0062] The first wavelength shifter (WLS1) can convert or shift the peak wavelength of incident light to the first peak wavelength. For example, the first wavelength shifter (WLS1) can convert and emit blue light provided by the display device (10) into red light having a single peak wavelength in the range of 610 nm to 650 nm. The first wavelength shifter (WLS1) may be a quantum dot, a quantum rod, or a phosphor. A quantum dot may be a particulate material that emits a specific color as electrons transition from the conduction band to the valence band.

[0063] For example, quantum dots can be semiconductor nanocrystalline materials. Depending on their composition and size, quantum dots can have a specific band gap and emit light with a specific wavelength after absorbing light. Examples of semiconductor nanocrystalline quantum dots include group IV nanocrystals, group II-VI compound nanocrystals, group III-V compound nanocrystals, group IV-VI nanocrystals, or combinations thereof.

[0064] For example, a quantum dot may have a core-shell structure comprising a core containing the aforementioned nanocrystal and a shell surrounding the core. The shell of the quantum dot may serve as a protective layer to maintain semiconductor properties by preventing chemical degradation of the core, and as a charging layer to impart electrophoretic properties to the quantum dot. The shell may be a single layer or a multilayer. The interface between the core and the shell may have a concentration gradient in which the concentration of elements present in the shell decreases toward the center. The shell of the quantum dot may be composed of metal or non-metal oxides, semiconductor compounds, or combinations thereof.

[0065] The light emitted by the first wavelength shifter (WLS1) may have a Full Width of Half Maximum (FWHM) of the emission wavelength spectrum of 45 nm or less, 40 nm or less, or 30 nm or less, and the color purity and color reproducibility of the color displayed by the display device (10) can be further improved. The light emitted by the first wavelength shifter (WLS1) may be emitted in multiple directions regardless of the incident direction of the incident light. Accordingly, the side visibility of red displayed in the first emission region (LA1) can be improved.

[0066] A portion of the blue light provided by the light-emitting element layer (EML) may pass through the first wavelength conversion unit (WLC1) without being converted into red light by the first wavelength shifter (WLS1). Among the blue light provided by the light-emitting element layer (EML), the light incident on the first color filter (CF1) without being converted by the first wavelength conversion unit (WLC1) may be blocked by the first color filter (CF1). Furthermore, among the blue light provided by the light-emitting element layer (EML), the red light converted by the first wavelength conversion unit (WLC1) may pass through the first color filter (CF1) and be emitted to the outside. Therefore, the first light-emitting region (LA1) may emit red light.

[0067] The second wavelength converter (WLC2) may be disposed in the second light-emitting region (LA2) on the first capping layer (CAP1). The second wavelength converter (WLC2) may be surrounded by the first light-blocking member (BK1). The second wavelength converter (WLC2) may include a second base resin (BS2), a second scatterer (SCT2), and a second wavelength shifter (WLS2).

[0068] The second base resin (BS2) may include a material with relatively high light transmittance. The second base resin (BS2) may be made of a transparent organic material. For example, the second base resin (BS2) may be made of the same material as the first base resin (BS1) or may be made of the material exemplified in the first base resin (BS1).

[0069] The second scatterer (SCT2) may have a refractive index different from that of the second base resin (BS2) and may form an optical interface with the second base resin (BS2). For example, the second scatterer (SCT2) may include a light-scattering material or light-scattering particles that scatter at least a portion of the transmitted light. For example, the second scatterer (SCT2) may be made of the same material as the first scatterer (SCT1) or may be made of the material exemplified in the first scatterer (SCT1). The second scatterer (SCT2) may scatter light in random directions regardless of the incident direction of the incident light without substantially changing the peak wavelength of the incident light.

[0070] The second wavelength shifter (WLS2) can convert or shift the peak wavelength of incident light to a second peak wavelength different from the first peak wavelength of the first wavelength shifter (WLS1). For example, the second wavelength shifter (WLS2) can convert and emit blue light provided by the display device (10) into green light having a single peak wavelength in the range of 510 nm to 550 nm. The second wavelength shifter (WLS2) may be a quantum dot, a quantum rod, or a phosphor. The second wavelength shifter (WLS2) may include a material of the same nature as the material exemplified in the first wavelength shifter (WLS1). The wavelength conversion range of the second wavelength shifter (WLS2) may be made of a quantum dot, a quantum rod, or a phosphor such that it is different from the wavelength conversion range of the first wavelength shifter (WLS1).

[0071] The light-transmitting unit (LTU) may be disposed in a third light-emitting region (LA3) on the first capping layer (CAP1). The light-transmitting unit (LTU) may be surrounded by a first light-blocking member (BK1). The light-transmitting unit (LTU) may transmit while maintaining the peak wavelength of the incident light. The light-transmitting unit (LTU) may include a third base resin (BS3) and a third scatterer (SCT3).

[0072] The third base resin (BS3) may include a material with relatively high light transmittance. The third base resin (BS3) may be made of a transparent organic material. For example, the third base resin (BS3) may be made of the same material as the first or second base resin (BS1, BS2), or may be made of the material exemplified in the first or second base resin (BS1, BS2).

[0073] The third scatterer (SCT3) may have a refractive index different from that of the third base resin (BS3) and may form an optical interface with the third base resin (BS3). For example, the third scatterer (SCT3) may include a light-scattering material or light-scattering particles that scatter at least a portion of the transmitted light. For example, the third scatterer (SCT3) may be made of the same material as the first or second scatterer (SCT1, SCT2) or may be made of the material exemplified in the first or second scatterer (SCT1, SCT2). The third scatterer (SCT3) may scatter light in random directions regardless of the incident direction of the incident light without substantially changing the peak wavelength of the incident light.

[0074] Since the wavelength conversion layer (WLCL) is placed directly on the second planarization layer (41) of the light-emitting element layer (EML), the display device (10) may not require a separate substrate for the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU). Accordingly, the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU) can be easily aligned with each of the first to third light-emitting regions (LA1, LA2, LA3), and the thickness of the display device (10) can be relatively reduced.

[0075] The second capping layer (CAP2) may cover the first and second wavelength conversion sections (WLC1, WLC2), the light transmission section (LTU), and the first light-blocking member (BK1). For example, the second capping layer (CAP2) may seal the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU) to prevent damage or contamination of the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU). The second capping layer (CAP2) may be made of the same material as the first capping layer (CAP1) or may be made of the material exemplified in the first capping layer (CAP1).

[0076] The third flattening layer (43) is disposed on top of the second capping layer (CAP2) to flatten the top of the first and second wavelength conversion sections (WLC1, WLC2) and the light transmission section (LTU). The third flattening layer (43) may include an organic material. For example, the third flattening layer (43) may include at least one of acrylic resin, epoxy resin, phenolic resin, polyamide resin, and polyimide resin.

[0077] The color filter layer (CFL) may include a second light-blocking member (BK2), first to third color filters (CF1, CF2, CF3), and a protective layer (PRT).

[0078] The second light-blocking member (BK2) may be placed on the third flattening layer (43) of the wavelength conversion layer (WLCL) in the first to third light-blocking regions (BA1, BA2, BA3). The second light-blocking member (BK2) may overlap with the first light-blocking member (BK1) or the second pattern (BNL2) in the thickness direction. The second light-blocking member (BK2) can block the transmission of light. The second light-blocking member (BK2) can improve color reproduction by preventing light from interfering and mixing between the first to third light-emitting regions (LA1, LA2, LA3). The second light-blocking member (BK2) may be arranged in a grid shape surrounding the first to third light-emitting regions (LA1, LA2, LA3) on a plane.

[0079] A first color filter (CF1) may be placed in a first light-emitting region (LA1) on the third flattening layer (43). The first color filter (CF1) may be surrounded by a second light-blocking member (BK2). The first color filter (CF1) may overlap with the first wavelength conversion unit (WLC1) in the thickness direction. The first color filter (CF1) may selectively transmit light of a first color (e.g., red light) and block or absorb light of a second color (e.g., green light) and light of a third color (e.g., blue light). For example, the first color filter (CF1) may be a red color filter and may include a red colorant. The red colorant may consist of a red dye or a red pigment.

[0080] The second color filter (CF2) may be placed in the second light-emitting region (LA2) on the third flattening layer (43). The second color filter (CF2) may be surrounded by a second light-blocking member (BK2). The second color filter (CF2) may overlap with the second wavelength conversion unit (WLC2) in the thickness direction. The second color filter (CF2) may selectively transmit light of the second color (e.g., green light) and block or absorb light of the first color (e.g., red light) and light of the third color (e.g., blue light). For example, the second color filter (CF2) may be a green color filter and may include a green colorant. The green colorant may consist of a green dye or a green pigment.

[0081] A third color filter (CF3) may be placed in a third light-emitting region (LA3) on the third flattening layer (43). The third color filter (CF3) may be surrounded by a second light-blocking member (BK2). The third color filter (CF3) may overlap with the light-transmitting portion (LTU) in the thickness direction. The third color filter (CF3) may selectively transmit light of a third color (e.g., blue light) and block or absorb light of a first color (e.g., red light) and light of a second color (e.g., green light). For example, the third color filter (CF3) may be a blue color filter and may include a blue colorant. The blue colorant may consist of a blue dye or a blue pigment.

[0082] The first to third color filters (CF1, CF2, CF3) can absorb a portion of the light entering from outside the display device (10) to reduce reflected light caused by external light. Accordingly, the first to third color filters (CF1, CF2, CF3) can prevent color distortion caused by external light reflection.

[0083] Since the first to third color filters (CF1, CF2, CF3) are placed directly on the third planarization layer (43) of the wavelength conversion layer (WLCL), the display device (10) may not require a separate substrate for the first to third color filters (CF1, CF2, CF3). Accordingly, the thickness of the display device (10) may be relatively reduced.

[0084] The third protective layer (PRT) can cover the first to third color filters (CF1, CF2, CF3). The third protective layer (PRT) can protect the first to third color filters (CF1, CF2, CF3).

[0085] The encapsulation layer (TFE) may be placed on the third protective layer (PRT) of the color filter layer (CFL). The encapsulation layer (TFE) may cover the upper surface and side surface of the display layer. For example, the encapsulation layer (TFE) may include at least one inorganic film to prevent oxygen or moisture from penetrating. Additionally, the encapsulation layer (TFE) may include at least one organic film to protect the display device (10) from foreign substances such as dust. For example, the encapsulation layer (TFE) may be formed with a structure in which at least one organic film is laminated between two inorganic films. The inorganic films may each include silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, silicon oxynitride, lithium fluoride, etc. The organic film may include acrylic resin, methacrylate resin, polyisoprene, vinyl resin, epoxy resin, urethane resin, cellulose resin, and perylene resin. However, the structure of the encapsulation layer (TFE) is not limited to the examples described above, and the laminated structure may be varied.

[0086] Hereinafter, the transistor layer (TFTL) and the light-emitting element layer (EML) will be described in detail through the planar and cross-sectional structures of a pixel of a display device according to one embodiment.

[0087] FIG. 3 is a plan view showing one pixel of a display device according to one embodiment.

[0088] Referring to FIG. 3, each of the plurality of pixels (PX) may include a plurality of subpixels (PXn, where n is an integer from 1 to 3). For example, one pixel (PX) may include a first subpixel (PX1), a second subpixel (PX2), and a third subpixel (PX3). The first subpixel (PX1) may emit light of a first color, the second subpixel (PX2) may emit light of a second color, and the third subpixel (PX3) may emit light of a third color. As an example, the first color may be blue, the second color may be green, and the third color may be red. However, not limited thereto, each subpixel (PXn) may emit light of the same color. Also, while FIG. 2 illustrates a pixel (PX) including three subpixels (PXn), not limited thereto, the pixel (PX) may include a larger number of subpixels (PXn).

[0089] Each subpixel (PXn) of the display device (10) may include a light-emitting region (EMA) and a non-light-emitting region (not shown). The light-emitting region (EMA) is a region where a light-emitting element (30) is placed and light of a specific wavelength range is emitted, and the non-light-emitting region may be a region where a light-emitting element (30) is not placed and light emitted from the light-emitting element (30) does not reach, so no light is emitted. The light-emitting region may include a region where a light-emitting element (30) is placed, and may include a region adjacent to the light-emitting element (30) where light emitted from the light-emitting element (30) is emitted.

[0090] Not limited thereto, the light-emitting region may also include a region where light emitted from a light-emitting element (30) is reflected or refracted by another member and emitted. A plurality of light-emitting elements (30) are arranged in each sub-pixel (PXn), and a light-emitting region may be formed by including the region where they are arranged and the region adjacent thereto.

[0091] Additionally, each subpixel (PXn) may include a cutting area (CBA) placed in a non-emissive region. The cutting area (CBA) may be placed on one side of the second direction (DR2) of the emitting region (EMA). The cutting area (CBA) may be placed between the emitting regions (EMA) of the subpixels (PXn) adjacent in the second direction (DR2). A plurality of emitting regions (EMA) and cutting areas (CBA) may be arranged in the display area (DPA) of the display device (10). For example, a plurality of emitting regions (EMA) and cutting areas (CBA) may be arranged repeatedly in the first direction (DR1), while the emitting regions (EMA) and cutting areas (CBA) may be arranged alternately in the second direction (DR2). Additionally, the spacing of the cutting areas (CBA) in the first direction (DR1) may be smaller than the spacing of the emitting regions (EMA) in the first direction (DR1). A second pattern (BNL2) is placed between the cutting regions (CBA) and the light-emitting regions (EMA), and the spacing between them may vary depending on the width of the second pattern (BNL2). Light is not emitted because the light-emitting element (30) is not placed in the cutting region (CBA), but some of the electrodes (21, 22) placed in each subpixel (PXn) may be placed therein. The electrodes (21, 22) placed in each subpixel (PXn) may be placed separately from each other in the cutting region (CBA).

[0092] FIG. 4 is a cross-sectional view taken along the Q1-Q1' line, Q2-Q2' line and Q3-Q3' line of FIG. 3. FIG. 4 illustrates a cross-section across both ends of a light-emitting element (30) placed in the first subpixel (PX1) of FIG. 3.

[0093] Referring to FIG. 4 in conjunction with FIG. 3, the display device (10) may include a substrate (11) and a semiconductor layer, a plurality of conductive layers, and a plurality of insulating layers disposed on the substrate (11). The semiconductor layer, the conductive layer, and the insulating layers may each constitute a circuit layer and a light-emitting element layer of the display device (10).

[0094] A light-blocking layer (BML) may be placed on a substrate (11). The light-blocking layer (BML) may be placed to overlap with the active layer (ACT) of the first transistor (T1) of the display device (10). The light-blocking layer (BML) may include a material that blocks light, thereby preventing light from being incident on the active layer (ACT) of the first transistor (T1). For example, the light-blocking layer (BML) may be formed of an opaque metallic material that blocks the transmission of light. However, it is not limited thereto, and in some cases, the light-blocking layer (BML) may be omitted. Additionally, the light-blocking layer (BML) may be electrically connected to the source electrode (SE) to suppress changes in the voltage of the transistor. Furthermore, the light-blocking layer (BML) may be used for wiring, such as power wiring, data wiring, or gate wiring.

[0095] The buffer layer (12) may be disposed over the entire surface of the substrate (11), including a light-blocking layer (BML). The buffer layer (12) is formed on the substrate (11) to protect the first transistors (T1) of the pixel (PX) from moisture penetrating through the substrate (11), which is susceptible to moisture permeability, and can perform a surface flattening function. The buffer layer (12) may be composed of a plurality of inorganic layers that are alternately stacked. For example, the buffer layer (12) may 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.

[0096] The semiconductor layer may be placed on the buffer layer (12). The semiconductor layer may include the active layer (ACT) of the first transistor (T1). These may be arranged to partially overlap with the gate electrode (G1) of the first gate conductive layer described later.

[0097] Meanwhile, the drawing shows only the first transistor (T1) among the transistors included in the subpixel (PXn) of the display device (10), but is not limited thereto. The display device (10) may include a larger number of transistors. For example, the display device (10) may include two or three transistors by including one or more additional transistors in addition to the first transistor (T1) for each subpixel (PXn).

[0098] The semiconductor layer may include polycrystalline silicon, single-crystal silicon, oxide semiconductors, etc. When the semiconductor layer includes an oxide semiconductor, each active layer (ACT) may include a plurality of conductive regions (ACTa, ACTb) and channel regions (ACTc) between them. The oxide semiconductor may be an oxide semiconductor containing indium (In). For example, the oxide semiconductor may be indium-tin oxide (ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-zinc-tin oxide (IZTO), indium-gallium-tin oxide (IGTO), indium-gallium-zinc oxide (IGZO), indium-gallium-zinc-tin oxide (IGZTO), etc.

[0099] In another embodiment, the semiconductor layer may include polycrystalline silicon. Polycrystalline silicon can be formed by crystallizing amorphous silicon, in which case the conductive regions of the active layer (ACT) may each be doped regions doped with impurities.

[0100] The first gate insulating layer (13) may be disposed on the semiconductor layer and the buffer layer (12). The first gate insulating layer (13) may be disposed on the buffer layer (12) including the semiconductor layer. The first gate insulating layer (13) may function as a gate insulating film for each transistor. The first gate insulating layer (13) may be composed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiOxNy), or may be formed in a stacked structure.

[0101] A first gate conductive layer may be disposed on a first gate insulating layer (13). The first gate conductive layer may include a gate electrode (G1) of a first transistor (T1) and a first capacitive electrode (CSE1) of a storage capacitor. The gate electrode (G1) may be disposed to overlap in the thickness direction with the channel region (ACTc) of the active layer (ACT). The first capacitive electrode (CSE1) may be disposed to overlap in the thickness direction with a second capacitive electrode (CSE2) described later. In one embodiment, the first capacitive electrode (CSE1) may be connected to the gate electrode (G1) and integrated. The first capacitive electrode (CSE1) may be disposed to overlap in the thickness direction with the second capacitive electrode (CSE2), and a storage capacitor may be formed between them.

[0102] The first gate conductive layer may be formed as a single layer or a multilayer composed of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy thereof. However, it is not limited thereto.

[0103] The first interlayer insulating layer (15) may be disposed on the first gate conductive layer. The first interlayer insulating layer (15) may function as an insulating film between the first gate conductive layer and other layers disposed thereon. Additionally, the first interlayer insulating layer (15) may be disposed to cover the first gate conductive layer and perform a protective function thereon. The first interlayer insulating layer (15) may be composed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiOxNy), or may be formed in a stacked structure.

[0104] The first data conductive layer may be disposed on the first interlayer insulating layer (15). The first data conductive layer may include a first source electrode (SE) and a first drain electrode (DE), a data line (DTL), and a second capacitance electrode (CSE2) of the first transistor (T1).

[0105] The first source electrode (SE) and the first drain electrode (DE) of the first transistor (T1) can each come into contact with the doping regions (ACTa, ACTb) of the active layer (ACT) through a contact hole penetrating the first interlayer insulating layer (15) and the first gate insulating layer (13). Additionally, the first source electrode (SE) of the first transistor (T1) can be electrically connected to the light-blocking layer (BML) through another contact hole.

[0106] The data line (DTL) can apply a data signal to another transistor (not shown) included in the display device (10). Although not shown in the drawing, the data line (DTL) can be connected to the source / drain electrodes of another transistor to transmit the signal applied from the data line (DTL).

[0107] The second capacitance electrode (CSE2) may be arranged to overlap the first capacitance electrode (CSE1) in the thickness direction. In one embodiment, the second capacitance electrode (CSE2) may be integrated and connected with the first source electrode (SE).

[0108] The first data conductive layer may be formed as a single layer or a multilayer composed of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy thereof. However, it is not limited thereto.

[0109] The second interlayer insulating layer (17) may be disposed on the first data conductive layer. The second interlayer insulating layer (17) may function as an insulating film between the first data conductive layer and other layers disposed thereon. Additionally, the second interlayer insulating layer (17) may cover the first data conductive layer and perform the function of protecting the first data conductive layer. The second interlayer insulating layer (17) may be composed of an inorganic layer including inorganic materials, such as silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy), or may be formed in a stacked structure.

[0110] The second data conductive layer may be disposed on the second interlayer insulating layer (17). The second data conductive layer may include a first voltage line (VL1), a second voltage line (VL2), and a first conductive pattern (CDP). A high potential voltage (or a first power supply voltage) supplied to the first transistor (T1) may be applied to the first voltage line (VL1), and a low potential voltage (or a second power supply voltage) supplied to the second electrode (22) may be applied to the second voltage line (VL2). Additionally, an alignment signal required to align the light-emitting element (30) during the manufacturing process of the display device (10) may be applied to the second voltage line (VL2).

[0111] The first conductive pattern (CDP) can be connected to the second capacitance electrode (CSE2) through a contact hole formed in the second interlayer insulating layer (17). The second capacitance electrode (CSE2) can be integrated with the first source electrode (SE) of the first transistor (T1), and the first conductive pattern (CDP) can be electrically connected to the first source electrode (SE). The first conductive pattern (CDP) also contacts the first electrode (21) described later, and the first transistor (T1) can transmit the first power supply voltage applied from the first voltage wiring (VL1) to the first electrode (21) through the first conductive pattern (CDP). Meanwhile, although the drawing shows the second data conductive layer including one second voltage wiring (VL2) and one first voltage wiring (VL1), it is not limited thereto. The second data conductive layer may include a larger number of first voltage wirings (VL1) and second voltage wirings (VL2). However, it is not limited to this, and the first data conductive layer may serve to transmit signals such as power supply voltage, in which case the second data conductive layer may be omitted.

[0112] The second data conductive layer may be formed as a single layer or a multilayer composed of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy thereof. However, it is not limited thereto.

[0113] The first planarization layer (19) may be disposed on the second data conductive layer. The first planarization layer (19) may include an organic insulating material, such as polyimide (PI), and may perform a surface planarization function.

[0114] A plurality of first patterns (BNL1), a plurality of electrodes (21, 22), a light-emitting element (30), a plurality of connecting electrodes (CNE1, CNE2) and a second pattern (BNL2) may be disposed on the first flattening layer (19). Additionally, a plurality of insulating layers (PAS1, PAS2, PAS3, PAS4) may be disposed on the first flattening layer (19).

[0115] A plurality of first patterns (BNL1) may be placed directly on the first planarization layer (19). The plurality of first patterns (BNL1) may have a shape that extends in a second direction (DR2) within each subpixel (PXn), but may not extend to other adjacent subpixels (PXn) in the second direction (DR2) and may be placed within the light-emitting region (EMA). Additionally, the plurality of first patterns (BNL1) may be spaced apart from each other in the first direction (DR1), and a light-emitting element (30) may be placed between them. The plurality of first patterns (BNL1) may be placed in each subpixel (PXn) to form a linear pattern in the display area (DPA) of the display device (10). Although two first patterns (BNL1) are shown in the drawing, they are not limited thereto. Depending on the number of electrodes (21, 22), a larger number of first patterns (BNL1) may be placed.

[0116] The first pattern (BNL1) may have a structure in which at least a portion protrudes with respect to the upper surface of the first flattening layer (19). The protruding portion of the first pattern (BNL1) may have an inclined side, and light emitted from the light-emitting element (30) may be reflected from the electrodes (21, 22) placed on the first pattern (BNL1) and emitted in the upward direction of the first flattening layer (19). The first pattern (BNL1) may provide an area where the light-emitting element (30) is placed and may also function as a reflective barrier that reflects light emitted from the light-emitting element (30) in the upward direction. The side of the first pattern (BNL1) may be inclined in a linear shape, but is not limited thereto, and the first pattern (BNL1) may have a shape of a semicircle or semi-ellipse with a curved outer surface. The first patterns (BNL1) may include an organic insulating material such as polyimide (PI), but are not limited thereto.

[0117] A plurality of electrodes (21, 22) may be disposed on a first pattern (BNL1) and a first flattening layer (19). The plurality of electrodes (21, 22) may include a first electrode (21) and a second electrode (22). The first electrode (21) and the second electrode (22) extend in a second direction (DR2), and may be disposed so as to be spaced apart from each other in a first direction (DR1).

[0118] The first electrode (21) and the second electrode (22) may each extend in a second direction (DR2) within a subpixel (PXn) and be separated from other electrodes (21, 22) in a cutting region (CBA). For example, a cutting region (CBA) may be placed between light-emitting regions (EMA) of subpixels (PXn) adjacent in the second direction (DR2), and the first electrode (21) and the second electrode (22) may be separated from other first electrodes (21) and second electrodes (22) placed in subpixels (PXn) adjacent in the second direction (DR2) in the cutting region (CBA). However, this is not limited thereto, and some electrodes (21, 22) may be placed extending beyond subpixels (PXn) adjacent in the second direction (DR2) without being separated for each subpixel (PXn), or only one of the first electrode (21) or the second electrode (22) may be separated.

[0119] The first electrode (21) may be electrically connected to the first transistor (T1) through the first contact hole (CT1), and the second electrode (22) may be electrically connected to the second voltage wiring (VL2) through the second contact hole (CT2). For example, the first electrode (21) may contact the first conductive pattern (CDP) through the first contact hole (CT1) penetrating the first flattening layer (19) in the portion extending in the first direction (DR1) of the second pattern (BNL2). The second electrode (22) may also contact the second voltage wiring (VL2) through the second contact hole (CT2) penetrating the first flattening layer (19) in the portion extending in the first direction (DR1) of the second pattern (BNL2). However, it is not limited thereto. In another embodiment, the first contact hole (CT1) and the second contact hole (CT2) may be placed within the light-emitting region (EMA) surrounded by the second pattern (BNL2) so as not to overlap with the second pattern (BNL2). In yet another embodiment, the second electrode (22) may be in direct contact with the first data wiring layer to apply voltage.

[0120] In the drawing, it is illustrated that one first electrode (21) and one second electrode (22) are arranged for each subpixel (PXn), but this is not limited thereto, and the number of first electrodes (21) and second electrodes (22) arranged for each subpixel (PXn) may be greater. Additionally, the first electrode (21) and the second electrode (22) arranged for each subpixel (PXn) may not necessarily have a shape that extends in one direction, and the first electrode (21) and the second electrode (22) may be arranged in various structures. For example, the first electrode (21) and the second electrode (22) may have a partially curved or bent shape, and one electrode may be arranged to surround the other electrode.

[0121] The first electrode (21) and the second electrode (22) may each be placed directly on the first patterns (BNL1). The first electrode (21) and the second electrode (22) may each be formed to have a width greater than that of the first pattern (BNL1). For example, the first electrode (21) and the second electrode (22) may each be placed to cover the outer surface of the first pattern (BNL1). The first electrode (21) and the second electrode (22) are each placed on the side of the first pattern (BNL1), and the gap between the first electrode (21) and the second electrode (22) may be narrower than the gap between the first patterns (BNL1). Additionally, at least a portion of the first electrode (21) and the second electrode (22) may be placed directly on the first flattening layer (19) so that they are placed on the same plane. However, they are not limited thereto. In some cases, the width of each electrode (21, 22) may be smaller than that of the first pattern (BNL1). However, each electrode (21, 22) is positioned to cover at least one side of the first pattern (BNL1) so as to reflect light emitted from the light-emitting element (30).

[0122] Each electrode (21, 22) may include a highly reflective conductive material. For example, each electrode (21, 22) may include a metal such as silver (Ag), copper (Cu), or aluminum (Al) as a highly reflective material, or an alloy including aluminum (Al), nickel (Ni), or lanthanum (La). Each electrode (21, 22) may reflect light emitted from the light-emitting element (30) and traveling toward the side of the first pattern (BNL1) toward the upper direction of each subpixel (PXn).

[0123] However, not limited thereto, each electrode (21, 22) may further include a transparent conductive material. For example, each electrode (21, 22) may include a material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ITZO (Indium Tin-Zinc Oxide), etc. In some embodiments, each electrode (21, 22) 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, each electrode (21, 22) may have a stacked structure such as ITO / Silver(Ag) / ITO / , ITO / Ag / IZO, or ITO / Ag / ITZO / IZO.

[0124] A plurality of electrodes (21, 22) are electrically connected to light-emitting elements (30), and a predetermined voltage may be applied so that the light-emitting elements (30) emit light. A plurality of electrodes (21, 22) are electrically connected to the light-emitting elements (30) through connecting electrodes (CNE1, CNE2), and an electrical signal applied to the electrodes (21, 22) can be transmitted to the light-emitting elements (30) through the connecting electrodes (CNE1, CNE2).

[0125] Either one of the first electrode (21) and the second electrode (22) may be electrically connected to the anode electrode of the light-emitting element (30), and the other may be electrically connected to the cathode electrode of the light-emitting element (30). However, this is not limited thereto, and the opposite case may also occur.

[0126] Additionally, each electrode (21, 22) may be utilized to form an electric field within a subpixel (PXn) to align the light-emitting element (30). The light-emitting element (30) may be positioned between the first electrode (21) and the second electrode (22) by means of an electric field formed on the first electrode (21) and the second electrode (22). The light-emitting element (30) of the display device (10) may be sprayed onto the electrodes (21, 22) through an inkjet printing process. When ink containing the light-emitting element (30) is sprayed onto the electrodes (21, 22), an alignment signal is applied to the electrodes (21, 22) to generate an electric field. The light-emitting element (30) dispersed in the ink may be aligned on the electrodes (21, 22) by receiving a dielectrophoretic force from the electric field generated on the electrodes (21, 22).

[0127] A first insulating layer (PAS1) may be disposed on the first flattening layer (19). The first insulating layer (PAS1) may be disposed to cover the first patterns (BNL1), and the first electrode (21) and the second electrode (22). The first insulating layer (PAS1) can protect the first electrode (21) and the second electrode (22) while simultaneously insulating them from each other. Additionally, it may prevent the light-emitting element (30) disposed on the first insulating layer (PAS1) from being damaged by direct contact with other components.

[0128] In one embodiment, the first insulating layer (PAS1) may include an opening (OP) that partially exposes the first electrode (21) and the second electrode (22). Each opening (OP) may partially expose a portion of each electrode (21, 22) that is positioned on the upper surface of the first pattern (BNL1). Some of the connecting electrodes (CNE1, CNE2) may come into contact with each electrode (21, 22) exposed through the opening (OP).

[0129] The first insulating layer (PAS1) may have a step formed such that a portion of its upper surface is sunken between the first electrode (21) and the second electrode (22). For example, as the first insulating layer (PAS1) is positioned to cover the first electrode (21) and the second electrode (22), its upper surface may be stepped according to the shape of the electrodes (21, 22) positioned below it. However, it is not limited thereto.

[0130] The second pattern (BNL2) may be placed on the first insulating layer (PAS1). The second pattern (BNL2) may be placed in a grid pattern across the entire front of the display area (DPA), including portions extending in the first direction (DR1) and the second direction (DR2) in a planar manner. The second pattern (BNL2) may be placed across the boundaries of each subpixel (PXn) to distinguish neighboring subpixels (PXn).

[0131] Additionally, the second pattern (BNL2) is positioned to surround the light-emitting region (EMA) and the cut-off region (CBA) placed for each subpixel (PXn), thereby distinguishing them. The first electrode (21) and the second electrode (22) can be extended in the second direction (DR2) and positioned across the portion of the second pattern (BNL2) extended in the first direction (DR1). The portion of the second pattern (BNL2) extended in the second direction (DR2) may have a greater width than the portion positioned between the light-emitting regions (EMA) and the portion positioned between the cut-off regions (CBA). Accordingly, the spacing between the cut-off regions (CBA) may be smaller than the spacing between the light-emitting regions (EMA).

[0132] The second pattern (BNL2) may be formed to have a greater height than the first bank (BNL1). The second pattern (BNL2) can prevent ink from overflowing into adjacent subpixels (PXn) during the inkjet printing process of the manufacturing process of the display device (10), thereby separating the inks in which different light-emitting elements (30) are dispersed for each subpixel (PXn) so that they do not mix with each other. The second pattern (BNL2) may include polyimide (PI) as in the first pattern (BNL1), but is not limited thereto.

[0133] A light-emitting element (30) may be disposed on a first insulating layer (PAS1). A plurality of light-emitting elements (30) may be spaced apart from each other along a second direction (DR2) in which each electrode (21, 22) is extended and may be aligned substantially parallel to each other. The light-emitting element (30) may have a shape that extends in one direction, and the direction in which each electrode (21, 22) is extended and the direction in which the light-emitting element (30) is extended may be substantially perpendicular. However, this is not limited thereto, and the light-emitting element (30) may be disposed obliquely rather than perpendicular to the direction in which each electrode (21, 22) is extended.

[0134] The light-emitting elements (30) placed in each subpixel (PXn) may include a light-emitting layer ('36' in FIG. 5) containing different materials and emit light of different wavelengths to the outside. Accordingly, light of the first color, the second color, and the third color may be emitted from the first subpixel (PX1), the second subpixel (PX2), and the third subpixel (PX3), respectively. However, this is not limited thereto, and each subpixel (PXn) may include the same type of light-emitting element (30) and emit light of substantially the same color.

[0135] The light-emitting element (30) may have both ends placed on each electrode (21, 22) between the first patterns (BNL1). The extended length of the light-emitting element (30) is longer than the gap between the first electrode (21) and the second electrode (22), and both ends of the light-emitting element (30) may be placed on the first electrode (21) and the second electrode (22), respectively. For example, the light-emitting element (30) may be placed such that one end is placed on the first electrode (21) and the other end is placed on the second electrode (22).

[0136] A plurality of layers of the light-emitting element (30) may be arranged in a direction perpendicular to the upper surface of the substrate (11) or the first flattening layer (19). The light-emitting element (30) may be arranged such that one extended direction is parallel to the upper surface of the first flattening layer (19), and a plurality of semiconductor layers included in the light-emitting element (30) may be arranged sequentially along a direction parallel to the upper surface of the first flattening layer (19). However, this is not limited thereto, and if the light-emitting element (30) has a different structure, a plurality of semiconductor layers may be arranged in a direction perpendicular to the upper surface of the first flattening layer (19).

[0137] Both ends of the light-emitting element (30) may each come into contact with connecting electrodes (CNE1, CNE2). For example, the light-emitting element (30) may not have an insulating film ('38' in FIG. 5) formed on the extended one-way end surface, and a portion of the semiconductor layer ('31', '32' in FIG. 5) or electrode layer ('37' in FIG. 5) may be exposed, and the exposed semiconductor layer ('31', '32' in FIG. 5) or electrode layer ('37' in FIG. 5) may come into contact with the connecting electrodes (CNE1, CNE2). However, not limited thereto, the light-emitting element (30) may have at least a portion of the insulating film (38) removed so that the sides of both ends of the semiconductor layer ('31', '32' in FIG. 5) are partially exposed. The side of the exposed semiconductor layer ('31', '32' in FIG. 5) may come into direct contact with the connecting electrode (CNE1, CNE2).

[0138] The second insulating layer (PAS2) may be partially disposed on the light-emitting element (30). For example, the second insulating layer (PAS2) may be disposed on the light-emitting element (30) with a width smaller than the length of the light-emitting element (30) so as to surround the light-emitting element (30) and expose both ends of the light-emitting element (30). The second insulating layer (PAS2) may be disposed to cover the light-emitting element (30), electrodes (21, 22), and the first insulating layer (PAS1) during the manufacturing process of the display device (10), and then removed to expose both ends of the light-emitting element (30). The second insulating layer (PAS2) may be disposed extending in a second direction (DR2) on the first insulating layer (PAS1) in a planar manner to form a linear or island pattern within each subpixel (PXn). The second insulating layer (PAS2) can protect the light-emitting element (30) and at the same time fix the light-emitting element (30) during the manufacturing process of the display device (10).

[0139] A plurality of connecting electrodes (CNE1, CNE2) and a third insulating layer (PAS3) may be disposed on the second insulating layer (PAS2).

[0140] A plurality of connecting electrodes (CNE1, CNE2) may have a shape extending in one direction and may be disposed on each electrode (21, 22). The connecting electrodes (CNE1, CNE2) may include a first connecting electrode (CNE1) disposed on the first electrode (21) and a second connecting electrode (CNE2) disposed on the second electrode (22). Each connecting electrode (CNE1, CNE2) may be disposed spaced apart from or facing each other. For example, the first connecting electrode (CNE1) and the second connecting electrode (CNE2) may be disposed on the first electrode (21) and the second electrode (22), respectively, and spaced apart from each other in a first direction (DR1). Each connecting electrode (CNE1, CNE2) may form a stripe-shaped pattern within the light-emitting region (EMA) of each subpixel (PXn).

[0141] A plurality of connecting electrodes (CNE1, CNE2) can each contact a light-emitting element (30). The first connecting electrode (CNE1) can contact one end of the light-emitting element (30), and the second connecting electrode (CNE2) can contact the other end of the light-emitting element (30). A semiconductor layer is exposed on both end surfaces of the light-emitting element (30) in an extended direction, and each connecting electrode (CNE1, CNE2) can be electrically connected to the semiconductor layer of the light-emitting element (30) by contacting it. One side of the connecting electrode (CNE1, CNE2) that contacts both ends of the light-emitting element (30) can be disposed on the second insulating layer (PAS2). Additionally, the first connecting electrode (CNE1) may contact the first electrode (21) through an opening (OP) that exposes a portion of the upper surface of the first electrode (21), and the second connecting electrode (CNE2) may contact the second electrode (22) through an opening (OP) that exposes a portion of the upper surface of the second electrode (22).

[0142] Each connecting electrode (CNE1, CNE2) may have a width measured in one direction that is smaller than the width measured in one direction of each electrode (21, 22). The connecting electrodes (CNE1, CNE2) may be arranged to contact one end and the other end of the light-emitting element (30) and simultaneously cover a portion of the upper surface of the first electrode (21) and the second electrode (22). However, not limited thereto, the connecting electrodes (CNE1, CNE2) may be formed with a width larger than that of the electrodes (21, 22) to cover both sides of the electrodes (21, 22).

[0143] The connecting electrodes (CNE1, CNE2) may include a transparent conductive material. For example, they may include ITO, IZO, ITZO, aluminum (Al), etc. Light emitted from the light-emitting element (30) may pass through the connecting electrodes (CNE1, CNE2) and proceed toward the electrodes (21, 22). However, it is not limited thereto.

[0144] In the drawing, two connecting electrodes (CNE1, CNE2) are shown arranged in one subpixel (PXn), but are not limited thereto. The number of each connecting electrode (CNE1, CNE2) may vary depending on the number of electrodes (21, 22) arranged in each subpixel (PXn).

[0145] The third insulating layer (PAS3) may be positioned to cover the first connecting electrode (CNE1). The third insulating layer (PAS3) may be positioned to cover one side on which the first connecting electrode (CNE1) is positioned relative to the second insulating layer (PAS2), including the first connecting electrode (CNE1). For example, the third insulating layer (PAS3) may be positioned to cover the first insulating layers (PAS1) positioned on the first connecting electrode (CNE1) and the first electrode (21). This positioning may be formed by a process in which the insulating material layer constituting the third insulating layer (PAS3) is positioned in the entire light-emitting region (EMA), and then a portion of the insulating material layer is removed to form the second connecting electrode (CNE2). In the above process, the insulating material layer forming the third insulating layer (PAS3) can be removed together with the insulating material layer forming the second insulating layer (PAS2), and one side of the third insulating layer (PAS3) can be aligned with one side of the second insulating layer (PAS2). One side of the second connecting electrode (CNE2) is placed on the third insulating layer (PAS3), and can be mutually insulated from the first connecting electrode (CNE1) with this in between.

[0146] The fourth insulating layer (PAS4) may be placed over the entire display area (DPA) of the substrate (11). The fourth insulating layer (PAS4) may function to protect the external environment of the components placed on the substrate (11). However, the fourth insulating layer (PAS4) may be omitted.

[0147] Each of the above-described first insulating layer (PAS1), second insulating layer (PAS2), third insulating layer (PAS3), and fourth insulating layer (PAS4) may include an inorganic insulating material or an organic insulating material. For example, the first insulating layer (PAS1), second insulating layer (PAS2), third insulating layer (PAS3), and fourth insulating layer (PAS4) may include inorganic insulating materials such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (AlxOy), aluminum nitride (AlN), etc. Alternatively, these may include, as organic insulating materials, acrylic resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene resin, polyphenylene sulfide resin, benzocyclobutene, cardo resin, siloxane resin, silsesquioxane resin, polymethyl methacrylate, polycarbonate, polymethyl methacrylate-polycarbonate synthetic resin, etc. However, they are not limited thereto.

[0148] FIG. 5 is a schematic diagram of a light-emitting element according to one embodiment.

[0149] Referring to FIG. 5, the light-emitting element (30) is a particle-shaped element and may be a rod or cylindrical shape having a predetermined aspect ratio. The light-emitting element (30) 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 (30) 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 (30) may have a nanometer scale, while the length of the light-emitting element (30) may have a micrometer scale. In some embodiments, some of the light-emitting elements (30) may have a diameter and / or length of a nanometer scale, while other parts of the light-emitting elements (30) may have a diameter and / or length of a micrometer scale.

[0150] In one embodiment, the light-emitting element (30) may be an inorganic light-emitting diode. Specifically, the light-emitting element (30) may include a semiconductor layer doped with any conductivity type (e.g., p-type or n-type) impurity. The semiconductor layer receives an electrical signal applied from an external power source and can emit it as light of a specific wavelength range.

[0151] A light-emitting element (30) according to one embodiment may include a first semiconductor layer (31), an active layer (33), a second semiconductor layer (32), and an electrode layer (37) that are sequentially stacked in the longitudinal direction. The light-emitting element may further include an insulating film (38) covering the outer surface of the first semiconductor layer (31), the second semiconductor layer (32), and the active layer (33).

[0152] The first semiconductor layer (31) may be an n-type semiconductor. When the light-emitting element (30) emits light in the blue wavelength range, the first semiconductor layer (31) may include a semiconductor material having the chemical formula AlxGayIn1-x-yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, it may be one or more of n-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The first semiconductor layer (31) may be doped with an n-type dopant, and the n-type dopant may be Si, Ge, Sn, etc. For example, the first semiconductor layer (31) may be n-GaN doped with n-type Si. The length of the first semiconductor layer (31) may be in the range of 1.5 μm to 5 μm, but is not limited thereto.

[0153] The second semiconductor layer (32) may be disposed on the light-emitting layer (36) described later. The second semiconductor layer (32) may be a p-type semiconductor, and when the light-emitting element (30) emits light in the blue or green wavelength range, the second semiconductor layer (32) may include a semiconductor material having the chemical formula AlxGayIn1-x-yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, it may be one or more of p-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The second semiconductor layer (32) may be doped with a p-type dopant, and the p-type dopant may be Mg, Zn, Ca, Se, Ba, etc. For example, the second semiconductor layer (32) may be p-GaN doped with p-type Mg. The length of the second semiconductor layer (32) may be in the range of 0.05㎛ to 0.10㎛, but is not limited thereto.

[0154] Meanwhile, the drawing shows the first semiconductor layer (31) and the second semiconductor layer (32) as being composed of a single layer, but is not limited thereto. Depending on the material of the light-emitting layer (36), the first semiconductor layer (31) and the second semiconductor layer (32) may further include a larger number of layers, such as a clad layer or a TSBR (Tensile strain barrier reducing) layer.

[0155] The light-emitting layer (36) may be disposed between the first semiconductor layer (31) and the second semiconductor layer (32). The light-emitting layer (36) may include a material having a single or multiple quantum well structure. If the light-emitting layer (36) includes a material having a multiple quantum well structure, it may have a structure in which a quantum layer and a well layer are alternately stacked in multiple layers. The light-emitting layer (36) may emit light by the coupling of electron-hole pairs according to an electrical signal applied through the first semiconductor layer (31) and the second semiconductor layer (32). If the light-emitting layer (36) emits light in the blue wavelength range, it may include a material such as AlGaN or AlGaInN. In particular, if the light-emitting layer (36) has a structure in which a quantum layer and a well layer are alternately stacked in a multiple quantum well structure, the quantum layer may include a material such as AlGaN or AlGaInN, and the well layer may include a material such as GaN or AlInN. For example, as described above, the light-emitting layer (36) may include AlGaInN as the quantum layer and AlInN as the well layer, and the light-emitting layer (36) may emit blue light having a central wavelength band in the range of 450 nm to 495 nm.

[0156] However, it is not limited thereto, and the light-emitting layer (36) 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 range of the emitted light. The light emitted by the light-emitting layer (36) is not limited to light in the blue wavelength range, and may emit light in the red or green wavelength range depending on the case. The length of the light-emitting layer (36) may have a range of 0.05㎛ to 0.10㎛, but is not limited thereto.

[0157] Meanwhile, the light emitted from the light-emitting layer (36) can be emitted not only to the longitudinal outer surface of the light-emitting element (30) but also to both sides. The directionality of the light emitted from the light-emitting layer (36) is not limited to one direction.

[0158] The electrode layer (37) may be an ohmic connection electrode. However, it is not limited thereto and may be a Schottky connection electrode. The light-emitting element (30) may include at least one electrode layer (37). FIG. 4 illustrates the light-emitting element (30) including one electrode layer (37), but it is not limited thereto. Depending on the case, the light-emitting element (30) may include a larger number of electrode layers (37) or may omit them. The description of the light-emitting element (30) described below can be applied in the same way even if the number of electrode layers (37) changes or other structures are included.

[0159] The electrode layer (37) can reduce the resistance between the light-emitting element (30) and the electrode or connecting electrode when the light-emitting element (30) is electrically connected to the electrode or connecting electrode in a display device (10) according to one embodiment. The electrode layer (37) may include a conductive metal. For example, the 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). Additionally, the electrode layer (37) may include an n-type or p-type doped semiconductor material. The electrode layer (37) may include the same material or different materials, but is not limited thereto.

[0160] The insulating film (38) may be arranged to surround the outer surface of the plurality of semiconductor layers and electrode layers described above. For example, the insulating film (38) may be arranged to surround the outer surface of at least the light-emitting layer (36) and may extend in one direction in which the light-emitting element (30) extends. The insulating film (38) may perform the function of protecting the members. The insulating film (38) may be formed to surround the side portions of the members, but the two ends in the longitudinal direction of the light-emitting element (30) may be formed to be exposed.

[0161] In the drawing, the insulating film (38) is shown extending in the longitudinal direction of the light-emitting element (30) to cover from the first semiconductor layer (31) to the side of the electrode layer (37), but is not limited thereto. The insulating film (38) may cover only the outer surface of a portion of the semiconductor layer, including the light-emitting layer (36), or cover only a portion of the outer surface of the electrode layer (37), so that the outer surface of each electrode layer (37) is partially exposed. Additionally, the insulating film (38) may be formed with a rounded upper surface in cross-section in an area adjacent to at least one end of the light-emitting element (30).

[0162] The thickness of the insulating film (38) may be in the range of 10 nm to 1.0 µm, but is not limited thereto. Preferably, the thickness of the insulating film (38) may be around 40 nm.

[0163] The insulating film (38) may include materials having insulating properties, such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum nitride (AlN), aluminum oxide (AlxOy), etc. The insulating film (38) may be formed as a single film or multiple films of materials having insulating properties. Accordingly, it is possible to prevent an electrical short circuit that may occur when the light-emitting layer (36) comes into direct contact with an electrode through which an electrical signal is transmitted to the light-emitting element (30). In addition, since the insulating film (38) protects the outer surface of the light-emitting element (30) including the light-emitting layer (36), it is possible to prevent a decrease in light-emitting efficiency.

[0164] Additionally, the outer surface of the insulating film (38) may be surface-treated. The light-emitting element (30) may be sprayed onto the electrode and aligned in a dispersed state within a predetermined ink. Here, in order for the light-emitting element (30) to remain dispersed without aggregating with other adjacent light-emitting elements (30) within the ink, the surface of the insulating film (38) may be treated to be hydrophobic or hydrophilic. For example, the outer surface of the insulating film (38) may be surface-treated with a material such as stearic acid, 2,3-naphthalene dicarboxylic acid, etc.

[0165] Among the display devices (10) described above, the light-emitting elements (30) can be sprayed onto a substrate (11) and aligned in a dispersed state within a predetermined ink. The ink is supplied through the inlet of the print head unit and, after being dispersed through the nozzles, the remaining ink is circulated through the outlet. However, as the light-emitting elements accumulate in the chamber above the nozzle, the nozzle may become clogged, and the ink may not be discharged. The non-discharge of ink may be visible as a stain on the display device, thereby degrading the display quality.

[0166] Below, an inkjet printing device capable of relieving nozzle clogging by removing light-emitting elements accumulated in the chamber of a print head unit will be described.

[0167] FIG. 6 is a schematic perspective view of an inkjet printing device according to one embodiment. FIG. 7 is a schematic bottom 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 diagram showing an ink circulation unit, a suction unit, and a print head unit according to one embodiment. FIG. 10 is a schematic cross-sectional view of an inkjet head according to one embodiment. Here, FIG. 3 shows the shape of a print head unit (100) according to one embodiment and a probe device (700) placed on a stage (STA) as viewed from the front.

[0168] Referring to FIGS. 6 to 9, an inkjet printing device (1000) according to one embodiment may include a print head unit (100) comprising a plurality of inkjet heads (300). The inkjet printing device (1000) may further include a stage (STA), an ink circulation unit (500), a suction unit (800), a probe device (700), and a base frame (600).

[0169] An inkjet printing device (1000) can spray a predetermined ink (90) onto a target substrate (SUB) using a print head unit (100). An electric field is generated on the target substrate (SUB) where the ink (90) is sprayed by a probe device (700), and particles such as light-emitting elements contained in the ink (90) can be aligned on the target substrate (SUB).

[0170] A target substrate (SUB) may be provided on a probe device (700), and the probe device (700) may form an electric field on the upper surface of the target substrate (SUB), and the electric field may be transmitted to ink (90) sprayed on the target substrate (SUB). Particles such as light-emitting elements (95) contained in the ink (90) may have a shape that extends in one direction and may be aligned so that the direction extended by the electric field faces one direction.

[0171] A stage (STA) may provide an area where a probe device (700) is placed. An inkjet printing device (1000) includes a first rail (RL1) and a second rail (RL2) that extend in a second direction (DR2), and the stage (STA) may be placed on the first rail (RL1) and the second rail (RL2). The stage (STA) may move in the second direction (DR2) via a separate moving member on the first rail (RL1) and the second rail (RL2). The probe device (700) may move in the second direction (DR2) together with the stage (STA), pass through the print head unit (100), and ink (90) may be sprayed over it. However, it is not limited thereto. Although the drawing shows a structure in which the stage (STA) moves, in some embodiments, the stage (STA) may be fixed and the print head unit (100) may move. In this case, the print head unit (100) may be mounted on a frame positioned on the first rail (RL1) and the second rail (RL2).

[0172] A print head unit (100) may be disposed on a base frame (600) and may include a plurality of inkjet heads (300). The print head unit (100) may spray a predetermined ink (90) onto a target substrate (SUB) provided to a probe device (700) using an inkjet head (300) connected to a separate ink storage unit.

[0173] The base frame (600) may include a support member (610) and a moving unit (630). The support member (610) may include a first support member (611) extending in a first direction (DR1) which is horizontal, and a second support member (612) connected to the first support member (611) and extending in a third direction (DR3) which is vertical. The extension direction of the first support member (611) may be the same as the first direction (DR1), which is the long side direction of the probe device (700). The print head unit (100) may be placed on the moving unit (630) mounted on the first support member (611).

[0174] The moving unit (630) may include a moving part (631) that is mounted on a first support part (611) and can move in one direction, and a fixed part (632) that is positioned on the lower surface of the moving part (631) and on which a print head unit (100) is positioned. The moving part (631) can move in a first direction (DR1) on the first support part (611), and the print head unit (100) can be fixed to the fixed part (632) and move in the first direction (DR1) together with the moving part (631).

[0175] A print head unit (100) is placed on a base frame (600) and can spray ink (90) provided from an ink reservoir onto a target substrate (SUB) through an inkjet head (300). The print head unit (100) may be spaced apart from a stage (STA) passing through the lower part of the base frame (600) at a specific distance. The distance at which the print head unit (100) is spaced apart from the stage (STA) can be adjusted by the height of the second support (612) of the base frame (600). The distance between the print head unit (100) and the stage (STA) can be adjusted within a range such that when a probe device (700) and a target substrate (SUB) are placed on the stage (STA), the print head unit (100) has a certain distance from the target substrate (SUB) to secure the space required for the printing process.

[0176] According to one embodiment, the print head unit (100) may include an inkjet head (300) comprising a plurality of nozzles (350). The inkjet head (300) may be disposed on the lower surface of the print head unit (100).

[0177] A plurality of inkjet heads (300) may be spaced apart from each other in one direction and arranged in one column or multiple columns. In the drawing, the inkjet heads (300) are shown arranged in two columns, with the inkjet heads (300) in each column arranged staggered from each other. However, this is not limited thereto, and the inkjet heads (300) may be arranged in a larger number of columns and may be arranged to overlap rather than stagger. The shape of the inkjet heads (300) is not particularly limited, but as an example, the inkjet heads (300) may have a rectangular shape.

[0178] Inkjet heads (300) may be arranged adjacent to each other, for example, two inkjet heads (300) may form a pack. However, the number of inkjet heads (300) included in one pack is not limited thereto, and for example, the number of inkjet heads (300) included in one pack may be from one to five. Additionally, although only six inkjet heads (300) arranged in the print head unit (100) are shown in the drawing, this is for schematically illustrating the print head unit (100), and the number of inkjet heads (300) is not limited thereto.

[0179] An inkjet head (300) positioned in a print head unit (100) can spray ink (90) onto a target substrate (SUB) positioned on top of a stage (STA). According to one embodiment, the print head unit (100) can move in one direction on a first support member (611), and the inkjet head (300) can move in said one direction to spray ink (90) onto the target substrate (SUB).

[0180] The print head unit (100) can move in a first direction (DR1) in which the first support member (611) is extended, and the inkjet head (300) can move in the first direction (DR1) and spray ink (90) onto the target substrate (SUB).

[0181] In some embodiments, the width of the target substrate (SUB) measured in the first direction (DR1) may be greater than the width of the print head unit (100). In this case, the print head unit (100) can move in the first direction (DR1) and spray ink (90) over the entire surface of the target substrate (SUB). Additionally, when a plurality of target substrates (SUB) are provided on the probe device (700), the print head unit (100) can move in the first direction (DR1) and spray ink (90) onto each of the plurality of target substrates (SUB).

[0182] However, not limited thereto, the print head unit (100) may be positioned outside the first rail (RL1) and the second rail (RL2) and then move in the first direction (DR1) to spray ink (90) onto the upper surface of the target substrate (SUB). When the stage (STA) moves in the second direction (DR2) and is positioned below the base frame (600), the print head unit (100) may move between the first rail (RL1) and the second rail (RL2) to spray ink (90) through the inkjet head (300). The operation of the inkjet head (300) is not limited thereto and may be modified in various ways within the range where a similar process can be implemented.

[0183] The inkjet printing device (1000) may further include an ink circulation unit (500). The ink circulation unit (500) can supply ink (90) to the print head unit (100), and the inkjet head (300) can discharge the supplied ink (90). The ink (90) circulates between the ink circulation unit (500) and the inkjet head (300), and some of the ink (90) supplied to the inkjet head (300) is discharged from the inkjet head (300), while the remaining portion can be supplied back to the ink circulation unit (500).

[0184] The ink circulation unit (500) can be connected to the inkjet head (300) through a first connecting pipe (IL1) and a second connecting pipe (IL2). For example, the ink circulation unit (500) can supply ink (90) to the inkjet head (300) through the first connecting pipe (IL1), and the flow rate of the supplied ink (90) can be controlled through the first valve (VA1). Additionally, the ink circulation unit (500) can supply the remaining portion of the ink (90) that is discharged from the inkjet head (300) through the second connecting pipe (IL2). The flow rate of the ink (90) supplied to the ink circulation unit (500) through the second connecting pipe (IL2) can be controlled through the second valve (VA2). As the ink (90) is circulated through the ink circulation unit (500), the variation in the number of light-emitting elements (95) contained in the ink (90) discharged from the inkjet head (300) can be minimized.

[0185] The ink circulation unit (500) may be mounted on the base frame (600), but is not limited thereto. The ink circulation unit (500) is provided in the inkjet printing device (1000), but its position or shape is not particularly limited. For example, the ink circulation unit (500) may be positioned via a separate device, and if connected to the inkjet head (300), various placements are possible within that range.

[0186] In some embodiments, the ink circulation unit (500) may include a first circulation ink storage unit (510), a second circulation ink storage unit (520), a third circulation ink storage unit (530), a circulation pump (550), a compressor (560), and a flow meter (580). The ink circulation unit (500) may have the second circulation ink storage unit (520), the circulation pump (550), and the third circulation ink storage unit (530) connected to an inkjet head (300), and these may form an ink circulation system.

[0187] The first circulating ink storage unit (510) may be a storage unit where manufactured ink (90) is prepared. Ink (90) comprising a solvent (91) and a bipolar element (95) is prepared in the first circulating ink storage unit (510) of the ink circulation unit (500), and the ink (90) may be supplied to the ink circulation system.

[0188] The second circulating ink storage unit (520) is connected to the first circulating ink storage unit (510) so that prepared ink (90) can be supplied. Additionally, the ink (90) remaining after being discharged from the inkjet head (300) can be supplied to the second circulating ink storage unit (520) through the second connecting pipe (IL2). The second circulating ink storage unit (520) can be positioned between the third circulating ink storage unit (530), the inkjet head (300), and the first circulating ink storage unit (510) to form an ink circulation system. If the second circulating ink storage unit (520) is omitted, an excess amount of ink (90) is supplied to the third circulating ink storage unit (530), and the dispersion of the bipolar element (95) may not be smooth. The ink circulation unit (500) may further include a second circulation ink storage unit (520) to prevent an excess amount of ink (90) from being supplied to the third circulation ink storage unit (530). For example, the second circulation ink storage unit (520) may serve as a buffer storage unit in which some of the ink (90) circulating in the ink circulation system is stored.

[0189] The ink (90) supplied to the second circulating ink storage unit (520) can be supplied to the third circulating ink storage unit (530) through a circulation pump (550). The circulation pump (550) may be a pump that transmits power to a fluid so that the ink (90) can be circulated within the ink circulation system. The ink (90) supplied to the second circulating ink storage unit (520) can be supplied to the third circulating ink storage unit (530) by the circulation pump (550). A flow meter (580) may be provided between the circulation pump (550) and the third circulating ink storage unit (530), and the flow meter (580) may measure the flow rate of the ink (90) supplied to the third circulating ink storage unit (530). The circulation pump (550) can control the flow rate of the ink (90) supplied to the third circulation ink storage unit (530) according to the flow rate of the ink (90) measured by the flow meter (580).

[0190] Additionally, the ink circulation unit (500) further comprises a compressor (560), and the compressor (560) can regulate the pressure within the third circulation ink storage unit (530). The compressor (560) can remove gas to create a vacuum inside the third circulation ink storage unit (530) or introduce an external inert gas to maintain a constant pressure. However, it is not limited thereto, and the compressor (560) of the ink circulation unit (500) may be omitted.

[0191] The third circulating ink storage unit (530) can be connected to the second circulating ink storage unit (520) via a circulation pump (550) to supply ink (90). Additionally, the third circulating ink storage unit (530) can supply ink (90) to an inkjet head (300) via a first connecting pipe (IL1). In one embodiment, the third circulating ink storage unit (530) may include a stirrer (ST), and the stirrer (ST) can disperse the light-emitting elements (95) within the ink (90). As the stirrer (ST) rotates, the ink (90) supplied to the third circulating ink storage unit (530) can maintain a dispersed state without the bipolar elements (95) settling. That is, the stirrer (ST) of the third circulating ink storage unit (530) can prevent the bipolar elements (95) from sinking to the bottom of the third circulating ink storage unit (530) and reducing the number of bipolar elements (95) in the ink (90) discharged through the inkjet head (300). The third circulating ink storage unit (530) can supply ink (90) in which the bipolar elements (95) are smoothly dispersed to the inkjet head (300), and the inkjet head (300) can discharge ink (90) containing a certain level or more of light-emitting elements (95).

[0192] In one embodiment, the ink (90) may comprise a solvent (91) and a plurality of light-emitting elements (95) contained within the solvent (91). In an exemplary embodiment, the ink (90) may be provided in a solution or colloidal state. 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 It may be glycolate (ethyl phthalyl ethyl glycolate), but is not limited thereto. A plurality of bipolar elements (95) may be included in a dispersed state within a solvent (91) and supplied to a print head unit (100) to be discharged.

[0193] Referring to FIG. 10, the inkjet head (300) may include a plurality of nozzles (350) to discharge ink (90) through the nozzles (350). The ink (90) discharged from the nozzles (350) may be sprayed onto a target substrate (SUB) provided on a stage (STA) or a probe device (700). The nozzles (350) may be located on the bottom surface of the inkjet head (300) and may be arranged along one direction in which the inkjet head (300) extends.

[0194] The inkjet head (300) may include a base part (310), an inner tube (330), a piezo chamber (360), a plurality of nozzles (350), an ejection part (370), and an actuator (390).

[0195] The base portion (310) may form the main body of the inkjet head (300). The base portion (310) may be attached to the print head unit (100). As described above with reference to FIG. 7, the base portion (310) may have a shape extending in a first direction (DR1) and a second direction (DR2). However, it is not limited thereto, and the base portion (310) may have a circular or polygonal shape.

[0196] The discharge section (370) may be a portion of the base section (310) of the inkjet head (300) where the piezo chamber (360) and the nozzle (350) are arranged. In the drawing, the discharge section (370) connected to the base section (310) and the discharge sections (370) spaced apart from it are arranged, and the piezo chamber (360) and the nozzle (350) are formed between them. However, substantially, the discharge sections (370) may be a single integrated member without being spaced apart from each other, and the nozzle (350) may be formed in the shape of a hole penetrating the discharge section (370). That is, a plurality of discharge sections (370) may be formed as a single member without being spaced apart from each other. However, this is not limited thereto, and in some embodiments, the inkjet head (300) may have a plurality of units arranged, each including a discharge section (370) in which a nozzle (350) is formed. In this case, multiple discharge sections (370) may be spaced apart from each other and connected to the base section (310).

[0197] The inner tube (330) is positioned within the base section (310) and connected to the internal flow path of the print head unit (100), and ink (90) can be supplied from the ink circulation section (500). The print head unit (100) is supplied with ink (90) through a first connecting tube (IL1) connected to the ink circulation section (500), and the ink (90) remaining after being discharged from the nozzle (350) can be supplied to the ink circulation section (500) through a second connecting tube (IL2). The inner tube (330) of the inkjet head (300) is supplied with ink (90) at an inlet (331) connected to the internal flow path of the print head unit (100), and the ink (90) remaining after being discharged can exit to the internal flow path through an outlet (333). The inlet (331) is connected to the first connecting tube (IL1), and the outlet (333) can be connected to the second connecting tube (IL2). The entrance (331) is positioned at one end of the inner tube (330), and the exit (333) can be positioned at the other end of the inner tube (330), that is, opposite the entrance (331) in the inner tube (330).

[0198] Additionally, the inkjet head (300) may include a filter (F) disposed within an inner tube (330). The filter (F) can prevent other substances, excluding the light-emitting element (95), from entering the nozzle (350) when the ink (90) flowing along the inner tube (330) enters the nozzle (350). Accordingly, it is possible to prevent the nozzle (350) from being clogged by foreign substances or to prevent foreign substances from being mixed into the ink (90) discharged from the nozzle (350).

[0199] The base portion (310) may have a shape that extends in one direction, and the inner tube (330) may be formed along the extension direction of the base portion (310). Ink (90) supplied through the print head unit (100) may flow through the inner tube (330) and then be discharged to the nozzle (350) through the piezo chamber (360) of the inkjet head (300).

[0200] A plurality of nozzles (350) may be disposed in a discharge section (370) located on one side of the base section (310), for example, the bottom side. The plurality of nozzles (350) are spaced apart from each other and arranged along the extension direction of the base section (310), and may discharge ink (90) by being connected to an inner tube (330) through a piezo chamber (360) that penetrates the discharge section (370) of the base section (310). Although not shown in the drawing, the plurality of nozzles (350) may be arranged in one row or multiple rows. Also, in the drawing, four nozzles (350) are shown formed in the inkjet head (300), but are not limited thereto. In some embodiments, the number of nozzles (350) included in the inkjet head (300) may be 128 to 1800. The nozzle (350) can discharge ink (90) introduced into the piezo chamber (360) along the inner tube (330). The amount of ink (90) ejected through the nozzle (350) can be adjusted according to the voltage applied to each nozzle (350). In one embodiment, the amount of ink (90) discharged once from each nozzle (350) may be 1 to 50 pl (Pico-litter), but is not limited thereto.

[0201] Ink (90) discharged through the nozzle (350) may include a solvent (91) and a light-emitting element (95) dispersed in the solvent (91). According to one embodiment, the light-emitting element (95) may have a shape that extends in one direction. The light-emitting element (95) may be randomly dispersed within the ink (90), flow along the inner tube (330), and then be supplied to the nozzle (350). As the light-emitting element (95) has a shape that extends in one direction, it may have an orientation direction that is the direction in which the long axis faces. Additionally, the light-emitting element (95) may include parts that have partially different polarities. For example, the light-emitting element (95) may include a first end having a first polarity and a second end having a second polarity, and the first end and the second end may be both ends in the direction of the long axis of the light-emitting element (95). The orientation direction of the light-emitting element (95) that extends in one direction may be defined based on the direction in which the first end faces. The light-emitting elements (95) flowing within the inner tube (330), piezo chamber (360), and nozzle (350) of the inkjet head (300) may not have a constant orientation direction and may be dispersed in random directions. However, not limited thereto, the light-emitting elements (95) may flow within the inner tube (330), piezo chamber (360), and nozzle (350) with a specific orientation direction.

[0202] The piezo chamber (360) is positioned between the nozzle (350) and the inner tube (330) and may be a place where ink (90) is temporarily stored before being discharged through the nozzle (350). When hydraulic pressure from the actuator (390) is applied to the piezo chamber (360), ink (90) can 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).

[0203] The actuator (390) may be positioned at the discharge portion (370) of the base portion (310). The actuator (390) may be positioned to surround the piezo chamber (360). The actuator (390) may apply hydraulic pressure to the ink (90) introduced into the piezo chamber (360) so that the ink (90) can be smoothly discharged through the nozzle (350). The actuator (390) may have substantially the same length as the discharge portion (370), but is not limited thereto. The actuator (390) may be positioned to surround the piezo chamber (360) in correspondence with it, and may be positioned apart from other actuators (390) by a distance equal to the distance between the piezo chamber (360).

[0204] According to one embodiment, the actuator (390) can control the amount of ink (90) discharged from the piezo chamber (360) through the nozzle (350). The actuator (390) can adjust the hydraulic pressure applied to the ink (90) and can control the amount of ink (90) discharged into a unit space during the printing process of the inkjet printing device (1000). For example, the amount of ink (90) discharged from the nozzle (350) once may be 1 to 50 pl (pico-litter), and the amount of ink (90) required in a unit space during one printing process may be 50 pl or more. In this case, the actuator (390) can control the amount of ink (90) discharged from the nozzle (350) during one printing process differently by adjusting the strength of the hydraulic pressure or the frequency, etc.

[0205] Meanwhile, as the inkjet printing device (1000) performs the ink (90) discharge process, the amount of ink (90) discharged gradually decreases. Specifically, the light-emitting element (95) contained in the ink (90) accumulates in the piezo chamber (360) of the inkjet head (300) and blocks the nozzle (350). As a result, the ink (90) cannot be discharged through the nozzle (350) and is discharged unevenly on the substrate, causing line stains to be visible and degrading the display quality.

[0206] According to one embodiment, an inkjet printing device (1000) includes a suction part (800) connected to an inkjet head (300) so as to be able to remove a light-emitting element (30) accumulated in a piezo chamber (360) of an inkjet head (300).

[0207] As illustrated in FIGS. 6 and 9, the inkjet printing device (1000) may include a suction part (800) extending from a second connecting pipe (IL2) connected to a print head unit (100). The suction part (800) can suck in ink (90) remaining in the print head unit (100) and discharge it to the outside. Specifically, the suction part (800) can suck in the light-emitting element (95) of the ink (90) accumulated in the piezo chamber (360) of the inkjet head (300) and discharge it to the outside through the outlet (333) of the inkjet head (300).

[0208] FIG. 11 is a drawing showing an inkjet printing device (1000) according to one embodiment.

[0209] Referring to FIG. 11 in conjunction with FIG. 9, the inkjet printing device (1000) may further include a suction unit (800). The suction unit (800) may be connected to an inkjet head (300) through a third connecting pipe (IL3). The suction unit (800) may include a third connecting pipe (IL3), a suction pump (810), and a suction ink storage unit (820). The suction unit (800) may have the third connecting pipe (IL3), the suction pump (810), and the suction ink storage unit (820) connected to the inkjet head (300), and these may form a single ink discharge system.

[0210] The third connector (IL3) may be a flow path for connecting the suction part (800) to the inkjet head (300). The third connector (IL3) may be connected to the second connector (IL2) and connected to the inkjet head (300) of the print head unit (100) through the second connector (IL2). For example, the third connector (IL3) may be connected to the second valve (VA2) of the second connector (IL2) connected to the inkjet head (300), thereby connecting to the inkjet head (300).

[0211] In one embodiment, the suction unit (800) may be disconnected from the ink circulation unit (500) while the ink (90) of the ink circulation unit (500) is supplied to the print head unit (100). The second valve (VA2) connected to the third connector (IL3) can selectively control the flow path through which the ink (90) moves to the second circulation ink storage unit (520) and the flow path through which the ink (90) moves to the third connector (IL3). To this end, the second valve (VA2) may be a three-way valve. A three-way valve is a valve having fluid inlets and outlets in three directions and can switch the flow path of the fluid.

[0212] In an exemplary embodiment, the second valve (VA2) can be switched to a first flow path (①) that moves from the print head unit (100) to the second circulating ink storage unit (520) through the second valve (VA2), and to a second flow path (②) that moves from the print head unit (100) to the third connecting pipe (IL3) through the second valve (VA2). While ink (90) is supplied to the print head unit (100) through the ink circulation unit (500) and the inkjet printing process is in progress, the second valve (VA2) can be switched to the first flow path (①). The ink (90) can be blocked from moving to the third connecting pipe (IL3) by the second valve (VA2) and can be moved to the second circulating ink storage unit (520). Additionally, while the suction process of sucking ink (90) from the inkjet head (300) of the print head unit (100) is in progress, the second valve (VA2) can be switched to the second flow path (②). The ink (90) is blocked from moving to the second circulating ink storage unit (520) by the second valve (VA2) and can be moved to the suction unit (800) through the third connecting pipe (IL3).

[0213] Ink (90) remaining in the inkjet head (300) of the print head unit (100) can be supplied to the suction ink storage unit (820) through the suction pump (810). The suction pump (810) may be a pump that transmits power to a fluid to suck ink (90) into the suction unit (800). The suction pump (810) operates during the suction process of sucking ink (90) from the inkjet head (300) of the print head unit (100) to suck ink (90) remaining in the inkjet head (300) and supply ink (90) to the suction ink storage unit (820).

[0214] The suction ink storage unit (820) can be supplied with ink (90) sucked into the suction unit (800). The suction ink storage unit (820) can be supplied with ink (90) remaining after being discharged from the inkjet head (300) through the suction pump (810). The suction ink storage unit (820) may be a storage unit where the supplied ink (90) is stored. The ink (90) stored in the suction ink storage unit (820) can be collected and reused as ink or disposed of.

[0215] Meanwhile, an inkjet printing device (1000) according to one embodiment may further include a dipping bath (900). The dipping bath (900) may be a storage unit containing a suction solution (910) that can be sucked in together with the ink (90) during the suction process of the print head unit (100).

[0216] The dipping bath (900) may be provided separately from the print head unit (100), such as the ink circulation unit (500) and the suction unit (800) in the inkjet printing device (1000). In an exemplary embodiment, the dipping bath (900) is positioned at one end of a stage ('STA' in FIG. 6) so that the print head unit (100) can descend and be immersed in the dipping bath (900).

[0217] The suction solution (910) contained in the dipping bath (900) may contain the material of the ink (90) discharged from the print head unit (100). Since the suction solution (910) is moved through the second connecting pipe (IL2) of the print head unit (100) and the ink circulation unit (500) from which the ink (90) is discharged, if the suction solution (910) remains in the print head unit (100) and the second connecting pipe (IL2), the composition of the ink (90) may change. To this end, the suction solution (910) contained in the dipping bath (900) may use the ink (90) or the solvent (91) of the ink (90). The ink (90) or the solvent (91) of the ink (90) is as described above, so a description is omitted.

[0218] An inkjet printing device (1000) according to the above embodiment includes a suction part (800) and a dipping bath (900), so that when non-ejection occurs during the inkjet printing process, the light-emitting element (30) accumulated in the inkjet head (300) can be sucked in to resolve the non-ejection.

[0219] Hereinafter, a method for resolving non-discharge of an inkjet printing device (1000) is disclosed, which can resolve non-discharge using the inkjet printing device (1000) described above.

[0220] FIG. 12 is a flowchart illustrating a method for resolving non-ejection of an inkjet printing device according to one embodiment.

[0221] A method for resolving non-discharge of an inkjet printing device according to one embodiment may include the steps of: immersing a print head unit (100) in a dipping bath (900) (S100); closing a first valve (VA1) and switching a second valve (VA2) to a second flow path (②) (S200); and driving a pressure pump (810) to suck up a suction solution (910) from the dipping bath (900) and supplying it to a suction ink storage unit (820) through a third connecting pipe (IL) (S300).

[0222] A method for resolving non-discharge of an inkjet printing device (1000) according to one embodiment may resolve non-discharge by immersing a print head unit (100) in a dipping bath (900) and driving a suction unit (800). Hereinafter, with further reference to other drawings, a method for resolving non-discharge of an inkjet printing device (1000) will be described in detail.

[0223] FIGS. 13 to 16 are step-by-step drawings illustrating a method for resolving non-ejection of an inkjet printing device according to one embodiment. Below, the method for resolving non-ejection of an inkjet printing device is explained in conjunction with FIG. 12 described above.

[0224] Referring to FIG. 13, an inkjet printing device (1000) is prepared, comprising a print head unit (100), a suction unit (800), and a dipping bath (900). The inkjet printing device (1000) may continuously discharge ink containing a light-emitting element, so that the light-emitting element accumulates in the inkjet head and is not discharged.

[0225] First, the print head unit (100) is immersed in a prepared dipping bath (900). (S100)

[0226] The dipping bath (900) may be filled with a suction solution (910) containing ink or a solvent contained in the ink. The print head unit (100) may have at least the entire inkjet head (300) immersed in the suction solution (910). Since the inkjet head (300) has a plurality of nozzles for sucking the suction solution (910), it is preferable that the plurality of nozzles be immersed in the suction solution (910).

[0227] Next, the first valve (VA1) provided in the inkjet printing device (1000) is closed, and the second valve (VA2) is switched to the second flow path (②). (S200)

[0228] An inkjet printing device (1000) may include a first connecting pipe (IL1) connected to one side of a print head unit (100), a second connecting pipe (IL2) connected to the other side of a print head unit (100), a first valve (VA2) provided in the first connecting pipe (IL1), and a second valve (VA2) provided in the second connecting pipe (IL2). First, the first valve (VA1) provided in the first connecting pipe (IL1) is closed. The first valve (VA1) serves to open and close the inside of the first connecting pipe (IL1), so that when the first valve (VA1) is closed, the movement of ink into the first connecting pipe (IL1) is blocked.

[0229] Next, the second valve (VA2) provided in the second connector (IL2) is switched to the second flow path (②). The second valve (VA2) is positioned between the second connector (IL2) and the third connector (IL3) to switch between the first flow path (①), through which the second connector (IL2) extends, and the second flow path (②), which extends from the second connector (IL2) to the third connector (IL3). As the second valve (VA2) is switched to the second flow path (②), a flow path is formed through the second connector (IL2) and the third connector (IL3) that allows ink to move. Accordingly, ink can move from the print head unit (100) to the second connector (IL2), the second valve (VA2), and the third connector (IL3). When the second valve (VA2) is switched to the second flow path (②), the first flow path (①) is closed, blocking the movement of ink.

[0230] Next, the pressure pump (810) is driven to suck up the suction solution (910) from the dipping bath (900) and supply it to the suction ink storage unit (820) through the third connecting pipe (IL). (S300)

[0231] An inkjet printing device (1000) according to one embodiment may include a suction unit (800) including a third connecting tube (IL3). The suction unit (800) may include a suction pump (810) connected to the third connecting tube (IL3) to suck up ink, and a suction ink storage unit (820) in which the sucked-up ink is stored.

[0232] When the pressure pump (810) is driven, a suction force is applied to the third connecting pipe (IL3), the second valve (VA2), the second connecting pipe (IL2), the print head unit (100), and the inkjet head (300) connected to the pressure pump (810), thereby sucking up the suction solution (910) from a plurality of nozzles of the inkjet head (300). The suction solution (910) sucked up from the inkjet head (300) is supplied to the suction ink storage unit (820) through the inside of the inkjet head (300) along the path of the print head unit (100), the second connecting pipe (IL2), the second valve (VA2), the third connecting pipe (IL3), and the pressure pump (810).

[0233] In one embodiment, the suction solution (910) sucked from a plurality of nozzles is moved to the second connecting pipe (IL2) together with the ink remaining in the inkjet head (300). Accordingly, the light-emitting elements accumulated in the piezo chamber of the inkjet head (300) are moved, thereby resolving the non-emission. This will be explained in more detail.

[0234] Referring to FIG. 14 and FIG. 15 in conjunction with FIG. 13, the inlet (331) of the inkjet head (300) is in a state where the movement of ink (90) is blocked by the closure of the first valve (VA1), and the outlet (333) may be an outlet (333) through which ink (90) is sucked out by the operation of the suction pump (810).

[0235] The suction solution (910) contained in the dipping bath (900) is drawn into a plurality of nozzles (350) by the suction force generated by the operation of the suction pump (810). The suction solution (910) drawn into the plurality of nozzles (350) passes through the piezo chamber (360) by the fluid flow, and moves to the inner tube (330) while pushing out the ink (90) containing the light-emitting element (95) remaining in the piezo chamber (360). The suction solution (910) drawn into the nozzle (350) with a very narrow diameter creates turbulent flow in the piezo chamber (360). Turbulence is an irregular flow of fluid, and for example, vortices are irregularly generated in the piezo chamber (360), causing the light-emitting elements (95) accumulated in the piezo chamber (360) to rise. The light-emitting elements (95) are drawn out of the piezo chamber (360) through the inner tube (330) to the outlet (333) by the turbulence generated by the ink (90) remaining in the piezo chamber (360) and the suction solution (910). Accordingly, the nozzle (350) clogged by the accumulation of light-emitting elements (95) in the piezo chamber (360) is cleared, thereby resolving the issue of non-discharge.

[0236] Referring again to FIG. 13, the ink (90) and suction solution (910) moving within the inkjet head (300) move to a second connecting pipe (IL2) connected to one side of the print head unit (100) and move to a third connecting pipe (IL3) through a second valve (VA2). Finally, the ink (90) and suction solution (910) are supplied to a suction ink storage unit (820) through a suction pump (810).

[0237] When the light-emitting elements (95) accumulated in the piezo chamber (360) of the inkjet head (300) are removed and the non-discharge of the inkjet printing device (1000) is resolved, the operation of the suction pump (810) can be stopped to complete the process of resolving the non-discharge of the inkjet printing device (1000).

[0238] Next, referring to FIG. 16, the inkjet printing device (1000) with the non-discharge resolved opens the first valve (VA1) and switches the second valve (VA2) to the first flow path (①). Then, by circulating the ink (90) through the ink circulation unit (500), a normal printing process using the inkjet printing device (1000) can be performed.

[0239] As described above, a method for resolving non-discharge of an inkjet printing device according to one embodiment is provided with a suction part (800) and a dipping bath (900) to remove light-emitting elements (95) accumulated in the piezo chamber (360) of an inkjet head (300) through a suction process of sucking a suction solution (910) from the nozzle (350) of an inkjet head (300). Accordingly, the stains caused by non-discharge of ink (90) can be improved, thereby improving the display quality.

[0240] The embodiments are described in more detail below through manufacturing examples and experimental examples.

[0241] <Manufacturing Example: Manufacture of an Inkjet Printing Device>

[0242] An inkjet printing device as illustrated in FIGS. 9 and FIGS. 11 was manufactured. The total number of nozzles in the inkjet printing device was 256.

[0243] <Experimental Example 1: Observation of Changes in Discharge State During Printing Process>

[0244] Printing was performed on an inkjet printing device with different printing conditions as follows, and the nozzle ejection state was observed.

[0245] Condition #1: Printing was performed by supplying only solvent to the inkjet printing device.

[0246] Condition #2: A light-emitting element was mixed in a solvent at 0.4 wt% and printed.

[0247] Condition #3: The printing process was performed for 30 minutes using Condition #2.

[0248] Condition #4: After the process of Condition #3 was performed, the printing process was performed for 2 more days.

[0249] <Experimental Example 2: Observation of Changes in Discharge State by Process for Resolving Nozzle Clogging>

[0250] Condition #4 was performed to prepare an inkjet printing device in which a total of 256 nozzles were clogged and not ejected. Then, processes to clear the nozzle clogging were sequentially performed under the following conditions, and the nozzle ejection status was observed.

[0251] Condition #5: Waveform frequency swap using an actuator was performed.

[0252] Condition #6: After the process of Condition #5 was completed, purging was performed under low pressure.

[0253] Condition #7: After the process of Condition #6 was completed, purging was performed at a higher pressure than Condition #6.

[0254] Condition #8: After the process of Condition #7 was completed, the suction process according to the aforementioned FIGS. 12 to 15 was performed.

[0255] The discharge state of the nozzle according to the aforementioned Experimental Examples 1 and 2 is shown in FIG. 17. FIG. 18 is an image of the nozzle discharge process taken every 10 microseconds (μs) for 60 microseconds (μs) after the process of Condition #4 is completed. FIG. 19 is an image of the nozzle discharge process taken every 10 microseconds (μs) for 60 microseconds (μs) after the process of Condition #8 is completed. Here, in FIG. 17, the horizontal axis represents each condition, and the vertical axis represents the number of nozzles.

[0256] Referring to Fig. 17, in condition #1, where only the solvent was printed, normal ejection occurred from all 256 nozzles. In condition #2, where the solvent mixed with the light-emitting element was printed, normal ejection also occurred from all nozzles. In condition #3, where printing was done for 30 minutes, 8 defective ejections occurred, and in condition #4, where printing was done for 2 days, non-ejection occurred from all 256 nozzles.

[0257] As shown in Fig. 18, it was confirmed that no ink was ejected from the nozzle where condition #4 was terminated.

[0258] Referring again to FIG. 17, in condition #5, where waveform frequency swapping was performed to resolve the non-ejection of an inkjet printing device in which all nozzles did not eject, normal ejection occurred in 63 nozzles, defective ejection occurred in 40 nozzles, and 153 nozzles still did not eject. In condition #6, where weak purging was performed, normal ejection occurred in 33 nozzles and 185 nozzles did not eject, so the number of nozzles ejecting normally actually decreased. In condition #7, where strong purging was performed, normal ejection occurred in 165 nozzles and 14 nozzles did not eject, so the non-ejection was improved to some extent.

[0259] Meanwhile, in condition #8, where the suction process illustrated in the aforementioned Figures 12 to 15 was performed, it was found that a total of 256 nozzles were discharged normally.

[0260] As shown in Fig. 19, it was confirmed that ink was discharged normally from the nozzle after condition #8 ended.

[0261] Through this, it was confirmed that the method for resolving non-discharge of an inkjet printing device according to one embodiment can resolve non-discharge of the inkjet printing device by performing a suction process with a suction part.

[0262] 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

[0263] 100: Print head unit 300: Inkjet head 350: Nozzle 360: Piezo Chamber 500: Ink circulation unit 510: First circulating ink storage unit 520: 2nd circulating ink storage unit 530: 3rd circulating ink storage unit 550: Circulation pump 800: Suction part 810: Suction pump 820: Suction ink reservoir IL1: 1st connector IL2: 2nd connector IL3: 3rd connection pipe VA1: 1st valve VA2: Second valve

Claims

Claim 1 A print head unit comprising a plurality of nozzles for discharging ink including a plurality of light-emitting elements; a dipping bath in which the print head unit is immersed and which contains a suction solution; a suction unit connected to the print head unit and which sucks in the suction solution to suck in the ink remaining in the print head unit; a first connecting pipe connected to one end of the print head unit to supply the ink to the print head unit; a second connecting pipe connected to the other end of the print head unit to move the ink from the print head unit; a first valve disposed in the first connecting pipe to regulate the supply of the ink; a second valve disposed in the second connecting pipe to regulate the flow rate of the ink; a first circulating ink storage unit in which the ink is stored; a second circulating ink storage unit connected to the second connecting pipe and which receives the ink from the first circulating ink storage unit; and a circulation pump for moving the ink from the second circulating ink storage unit. An inkjet printing device further comprising a third circulating ink storage unit that receives ink from the circulation pump, wherein the third circulating ink storage unit is connected to the first connecting pipe to supply ink to the print head unit, and the print head unit includes an inkjet head, wherein the inkjet head includes an inner pipe passing through the interior of the inkjet head; and a plurality of piezo chambers connected downward from the inner pipe. Claim 2 delete Claim 3 An inkjet printing device according to claim 1, wherein the suction part comprises a third connecting pipe connected to the second connecting pipe; a suction pump connected to the third connecting pipe to transmit power to the ink; and an ink storage part connected to the end of the third connecting pipe to store the ink supplied through the suction pump. Claim 4 An inkjet printing device according to claim 3, wherein the third connector is connected to the second connector through the second valve, and the ink moves to the second connector or the third connector depending on the opening and closing of the second valve. Claim 5 In claim 4, the inkjet printing device wherein the second valve is a three-way valve. Claim 6 In claim 1, the dipping bath contains the suction solution and is an inkjet printing device provided separately from the print head unit. Claim 7 In claim 6, the suction solution is an inkjet printing device in which the ink or a solvent contained in the ink is. Claim 8 delete Claim 9 An inkjet printing device according to claim 1, wherein the inkjet head comprises an inlet connected from the first connecting tube; and an outlet disposed opposite the inlet in the inner tube and connected to the second connecting tube, and wherein the plurality of nozzles are each disposed in the plurality of piezo chambers. Claim 10 A print head unit comprising a plurality of nozzles for discharging ink including a plurality of light-emitting elements; a dipping bath in which the print head unit is immersed and which contains a suction solution; a suction unit connected to the print head unit and which sucks in the suction solution to suck in the ink remaining in the print head unit; a first connecting pipe connected to one end of the print head unit to supply the ink to the print head unit; a second connecting pipe connected to the other end of the print head unit to move the ink from the print head unit; a first valve disposed in the first connecting pipe to regulate the supply of the ink; a second valve disposed in the second connecting pipe to regulate the flow rate of the ink; a first circulating ink storage unit in which the ink is stored; a second circulating ink storage unit connected to the second connecting pipe and which receives the ink from the first circulating ink storage unit; a circulation pump that moves the ink from the second circulating ink storage unit; and a third circulating ink storage unit that receives the ink from the circulation pump, wherein the third circulating ink storage unit is connected to the first connecting pipe and the print A method for resolving non-discharge of an inkjet printing device that supplies ink to a head unit, comprising: immersing the print head unit in the dipping bath; closing the first valve connected to one end of the print head unit and switching the second valve connected to the other end; and driving the suction pump of the suction part connected to the second valve and sucking the suction solution contained in the dipping bath through the print head unit, together with the ink remaining in the print head unit, wherein the print head unit includes an inkjet head, and the inkjet head includes an inner tube passing through the interior of the inkjet head; and a plurality of piezo chambers connected downward from the inner tube. Claim 11 In claim 10, the step of immersing the print head unit in the dipping bath comprises immersing the print head unit in the suction solution such that a plurality of nozzles of the inkjet head provided in the print head unit are submerged therein, a method for resolving non-ejection of an inkjet printing device. Claim 12 delete Claim 13 A method for resolving non-ejection of an inkjet printing device according to claim 10, wherein the suction part comprises a third connecting pipe connected to the second connecting pipe; a suction pump connected to the third connecting pipe to transmit power to the ink; and a suction ink storage part connected to the end of the third connecting pipe to store the ink supplied through the suction pump. Claim 14 In claim 13, the step of closing the first valve and switching the second valve is a method for resolving non-ejection of an inkjet printing device, wherein the movement of the ink into the first connecting pipe is blocked by closing the first valve, and a movable flow path for the ink is formed through the second connecting pipe and the third connecting pipe by switching the second valve. Claim 15 A method for resolving non-discharge of an inkjet printing device according to claim 13, wherein suction force acts through the third connecting pipe, the second valve, the second connecting pipe, and the print head unit connected to the suction pump by driving the suction pump to suck up the suction solution. Claim 16 In claim 15, the inkjet head comprises a plurality of nozzles, and the method for resolving non-discharge of an inkjet printing device by sucking the suction solution from the plurality of nozzles. Claim 17 In claim 16, a method for resolving non-ejection of an inkjet printing device, wherein the suction solution is sucked through the plurality of nozzles and forms turbulence within the piezo chamber connected to the plurality of nozzles. Claim 18 A method for resolving non-discharge of an inkjet printing device according to claim 17, wherein the light-emitting element of the ink accumulated in the piezo chamber is floated by the turbulence, and the ink containing the light-emitting element together with the suction solution is sucked into the suction part through the second connecting pipe. Claim 19 In claim 18, a method for resolving non-ejection of an inkjet printing device in which the ink and the suction solution are stored in the suction ink storage unit through the suction pump of the suction unit. Claim 20 A method for resolving non-ejection of an inkjet printing device according to claim 13, wherein, after the step of sucking in the suction solution and the ink, the first valve is opened and the second valve is switched to block the movement of the ink to the third connecting pipe.

Images