Inkjet printing apparatus

Abstract

An inkjet printing device includes a stage that moves in a first direction; an inkjet device that sprays ink onto the stage; and a drying device that dries the ink sprayed onto the stage, wherein the drying device includes an electric field generating device that generates an electric field on the stage.

Description

Technology Field

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

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

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

[0004] Inorganic light-emitting diodes (LEDs) utilizing inorganic semiconductors as fluorescent materials possess durability even in high-temperature environments and have the advantage of higher blue light efficiency compared to organic light-emitting diodes (OLEDs). Furthermore, regarding the manufacturing process, which was previously identified as a limitation of conventional LED devices, a transfer method using dielectrophoresis (DEP) has been developed. Consequently, research on inorganic LEDs, which offer superior durability and efficiency compared to OLEDs, is continuing.

[0005] Meanwhile, an inkjet printing device may be used to transfer an inorganic light-emitting diode element or to form an organic layer included in a display device using dielectrophoresis. 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 predetermined substrate. The problem to be solved

[0006] The problem that the present invention aims to solve is to provide an inkjet printing device capable of improving miss probing of a probe pad.

[0007] 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

[0008] An inkjet printing device according to one embodiment for solving the above problem includes a stage that moves in a first direction; an inkjet device that sprays ink onto the stage; and a drying device that dries the ink sprayed onto the stage, wherein the drying device includes an electric field generating device that generates an electric field on the stage.

[0009] An inkjet printing device according to another embodiment for solving the above problem comprises: a stage moving in a first direction; an inkjet device for spraying ink onto the stage; a light irradiation device for irradiating light onto the stage; and a drying device for drying the ink sprayed onto the stage, wherein the inkjet device, the light irradiation device, and the drying device are arranged in a line along the first direction, and the drying device includes an electric field generating device for generating an electric field on the stage.

[0010] Specific details of other embodiments are included in the detailed description and drawings. Effects of the invention

[0011] According to the embodiments, the miss probing of the probe pad can be improved.

[0012] 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

[0013] FIG. 1 is a schematic diagram of an inkjet printing device according to one embodiment. FIG. 2 is a perspective view showing the arrangement of an inkjet device and a light irradiation device according to one embodiment. FIG. 3 is a perspective view showing the arrangement of a drying device and an inspection device according to one embodiment. FIG. 4 is a plan view showing an inkjet device and a light irradiation device according to one embodiment. FIG. 5 is a cross-sectional view showing ink being ejected from an inkjet device according to one embodiment. FIG. 6 is a cross-sectional view showing ink discharged from an inkjet device according to one embodiment. FIG. 7 is a cross-sectional view showing a drying device according to one embodiment. FIG. 8 is a top view showing a drying device according to one embodiment. FIG. 9 is a schematic diagram showing the operation of an electric field generating device according to one embodiment. FIG. 10 is a plan view of a display device according to one embodiment. FIG. 11 is a plan view showing one pixel of a display device according to one embodiment. FIG. 12 is a cross-sectional view taken along the lines IIIa-IIIa', IIIb-IIIb', and IIIc-IIIc' of FIG. 11. Specific details for implementing the invention

[0014] 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.

[0015] Elements or layers referred to as "on" another element or layer include cases where another layer or element is interposed directly above or in the middle of another element. Likewise, "below," "left," and "right" refer to cases where they are interposed immediately adjacent to another element or where another layer or material is interposed in the middle. Throughout the specification, the same reference numerals refer to the same components.

[0016] 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.

[0017] Hereinafter, embodiments will be described with reference to the attached drawings.

[0018] FIG. 1 is a schematic diagram of an inkjet printing device according to one embodiment. FIG. 2 is a perspective view showing the arrangement of an inkjet device, an electric field generating device, and a light irradiation device according to one embodiment. FIG. 3 is a perspective view showing the arrangement of a drying device and an inspection device according to one embodiment.

[0019] FIG. 1 schematically illustrates the arrangement of each component included in an inkjet printing device (1000), FIG. 2 illustrates the inkjet device (300) and light irradiation device (500; 510, 520) of the inkjet printing device (1000), and FIG. 3 illustrates the drying device (800) and inspection device (900) of the inkjet printing device (1000). FIG. 1 illustrates the inkjet printing device (1000) viewed from above.

[0020] Referring to FIGS. 1 to 3, an inkjet printing device (1000) according to one embodiment includes a stage (STA), an inkjet device (300), a plurality of light irradiation devices (500), and a drying device (800). Additionally, the inkjet printing device (1000) may further include an inspection device (900).

[0021] In FIGS. 1 to 3, a first direction (DR1), a second direction (DR2), and a third direction (DR3) are defined. The first direction (DR1) and the second direction (DR2) are located on the same plane and are orthogonal to each other, and the third direction (DR3) is a direction perpendicular to the first direction (DR1) and the second direction (DR2), respectively. The first direction (DR1) can be understood to mean the horizontal direction in the drawing, the second direction (DR2) to mean the vertical direction in the drawing, and the third direction (DR3) to mean the upper and lower directions in the drawing.

[0022] The inkjet printing device (1000) can spray ink onto a stage (STA) or a target substrate (SUB) placed on the stage (STA) using an inkjet head (330).

[0023] As the stage (STA) moves through the light irradiation device (500) and the drying device (800), the bipolar element can be printed on the target substrate (SUB). In this specification, 'printing' of the bipolar element may mean discharging or spraying the bipolar element onto a certain target using an inkjet printing device (1000). For example, printing the bipolar element may mean, in addition to spraying the bipolar element onto the target substrate (SUB) using an inkjet device (300), the bipolar element or ink may settle on the target substrate (SUB). Below, the configurations of the inkjet printing device (1000) and the process of printing the bipolar element using it will be described by example.

[0024] In order to print a bipolar element on a target substrate (SUB), a process is performed using an inkjet device (300) that sprays ink containing a bipolar element, a light irradiation device (500), and a drying device (800) that places the bipolar element on the target substrate (SUB) and aligns the bipolar element.

[0025] In an inkjet printing device (1000) according to one embodiment, a process of printing a bipolar element can be continuously performed as a target substrate (SUB) moves through an inkjet device (300), a light irradiation device (500), and a drying device (800).

[0026] In the inkjet printing device (1000), multiple devices may be arranged sequentially in one direction so that different processes can be performed continuously. For example, in the inkjet printing device (1000), an inkjet device (300), a light irradiation device (500), and a drying device (800) may be arranged in a line along the direction in which the stage (STA) moves.

[0027] FIG. 4 is a plan view showing an inkjet device and a light irradiation device according to one embodiment. FIG. 4 schematically illustrates the arrangement of the stage (STA), inkjet device (300), and light irradiation device (500) of the inkjet printing device (1000).

[0028] Referring to FIG. 4 in addition to FIG. 1 to 3, the stage (STA) may provide an area where a target substrate (SUB) is placed. The shape of the stage (STA) is not particularly limited, but as an example, the stage (STA) may have a rectangular shape with both sides extended in a first direction (DR1) and a second direction (DR2). The stage (STA) may include a long side extended in the first direction (DR1) and a short side extended in the second direction (DR2). However, the overall planar shape of the stage (STA) may vary depending on the planar shape of the target substrate (SUB). For example, if the target substrate (SUB) is a rectangular shape in planar form, the shape of the stage (STA) may be rectangular as shown in the drawings, and if the target substrate (SUB) has a circular planar form, the planar shape of the stage (STA) may also be circular. However, it is not limited thereto, and the shape of the stage (STA) and the shape of the target substrate (SUB) may be different from each other.

[0029] An inkjet printing device (1000) includes a plurality of first rails (RL1) extended in a second direction (DR2), and a stage (STA) is positioned on the plurality of first rails (RL1). The first rails (RL1) may be positioned extending in a second direction (DR2).

[0030] The stage (STA) can move in a second direction (DR2) via a moving member (not shown) on the first rail (RL1). When a target substrate (SUB) is placed on the upper part of the stage (STA), it can reciprocate in the second direction (DR2) along the first rail (RL1), and particles can be printed on the target substrate (SUB).

[0031] Multiple aligners (AL) may be placed on the stage (STA). The aligners (AL) are placed on each side of the stage (STA), and the area surrounded by the multiple aligners (AL) may be the area where the target substrate (SUB) is placed. In the drawing, two aligners (AL) are spaced apart and placed on each side of the stage (STA), and a total of eight aligners (AL) are shown placed on the stage (STA). However, this is not limited thereto, and the number and placement of the aligners (AL) may vary depending on the shape or type of the target substrate (SUB). Additionally, the aligners (AL) may be omitted in some cases.

[0032] A target substrate (SUB) may be prepared on a stage (STA). The target substrate (SUB) may provide a target space on which particles printed by an inkjet printing device (1000) are placed. As described below, specific components may be placed on the target substrate (SUB), and the particles may be placed on or printed on the components. The target substrate (SUB) may be positioned on the stage (STA) in conjunction with an aligner (AL) to account for the location where the particles are printed.

[0033] The inkjet device (300) may be placed in a first frame (FM1) and may include a plurality of inkjet heads ('330' in FIG. 5). The inkjet device (300) may spray ink ('90' in FIG. 5) onto a target substrate (SUB) using an inkjet head (330) connected to an ink circulation unit (600).

[0034] The inkjet printing device (1000) may include a plurality of frames (FM1 to FM5). The frames (FM1 to FM5) may be placed on the upper part of the first rail (RL1) and devices on which a printing process of a bipolar element (95) is performed may be placed.

[0035] The first frame (FM1) may include a plurality of support members (FM_C, FM_R). The support members (FM_C, FM_R) may include a first support member (FM_C) extended in a first direction (DR1) which is horizontal, and a second support member (FM_R) connected to the first support member (FM_C) and extended in a third direction (DR3) which is vertical. The extension direction of the first support member (FM_C) may be the same as the first direction (DR1), which is the long side direction of the stage (STA). An inkjet device (300) may be mounted on the first support member (FM_C).

[0036] The inkjet device (300) may be spaced apart from the stage (STA) passing through the lower part of the first frame (FM1) at a certain distance. The distance between the inkjet device (300) and the stage (STA) may be adjusted by the height of the second support member (FM_R) of the first frame (FM1). The distance between the inkjet device (300) and the stage (STA) may be adjusted within a range such that when a target substrate (SUB) is placed on the stage (STA), the inkjet device (300) has a certain distance from the target substrate (SUB) to secure the space required for the printing process.

[0037] FIG. 5 is a cross-sectional view showing ink being ejected from an inkjet device according to one embodiment. FIG. 6 is a cross-sectional view showing ink ejected from an inkjet device according to one embodiment.

[0038] Referring to FIGS. 5 and 6, the inkjet device (300) may include a first base portion (310) and a plurality of inkjet heads (330) disposed on the bottom surface of the first base portion (310). The inkjet heads (330) include a plurality of nozzles (335), and ink provided from the ink circulation portion (600) may be discharged through the nozzles (335) of the inkjet heads (330).

[0039] A plurality of inkjet heads (330) may be spaced apart from each other in one direction and arranged in one column or multiple columns. Although the drawings show the inkjet heads (330) arranged in one column, they are not limited thereto. The inkjet heads (330) may be arranged in a greater number of columns, and may be arranged staggered from each other or adjacent to each other. The shape of the inkjet heads (330) is not particularly limited, but as an example, the inkjet heads (330) may have a rectangular shape.

[0040] In some embodiments, at least one inkjet head (330), for example, two inkjet heads (330) may be arranged adjacent to each other to form a pack. However, the number of inkjet heads (330) included in one pack is not limited thereto, and for example, the number of inkjet heads (330) included in one pack may be from one to five. Also, although only five inkjet heads (330) arranged in the inkjet device (300) are shown in the drawing, this is for schematically illustrating the inkjet device (300), and the number of inkjet heads (330) is not limited thereto.

[0041] In some embodiments, the width of the target substrate (SUB) measured in the first direction (DR1) may be greater than the width of the inkjet device (300). In this case, the inkjet device (300) 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 stage (STA), the inkjet device (300) can move in the first direction (DR1) and spray ink (90) onto each of the plurality of target substrates (SUB).

[0042] However, not limited thereto, the inkjet device (300) 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 target substrate (SUB). When the stage (STA) of the inkjet device (300) moves in the second direction (DR2) and is positioned below the first frame (FM1), it may move between the first rails (RL1) and spray ink (90) through the inkjet head (330). The operation of the inkjet head (330) is not limited thereto and may be modified in various ways within the range that can implement a similar process.

[0043] An inkjet head (330) placed in an inkjet device (300) can spray ink (90) onto a target substrate (SUB) placed on top of a stage (STA).

[0044] In one embodiment, the ink (90) may comprise a solvent (91) and a plurality of bipolar 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 an inkjet device (300) to be ejected.

[0045] The inkjet printing device (1000) may further include an ink circulation unit (600). The ink circulation unit (600) may supply ink (90) to the inkjet device (300), and the inkjet head (330) may discharge the supplied ink (90). The ink (90) circulates between the ink circulation unit (600) and the inkjet head (330), and some of the ink (90) supplied to the inkjet head (330) may be discharged from the inkjet head (330), while the remainder may be supplied back to the ink circulation unit (600). In some embodiments, the ink circulation unit (600) may include a plurality of ink storage units, a pressure pump, a compressor, and a flow meter. The ink circulation unit (600) may have an ink storage unit connected to the inkjet head (330), and these may form a single ink circulation system. A detailed description thereof is omitted.

[0046] The ink circulation unit (600) can be connected to the inkjet head (330) through the first connecting pipe (IL1) and the second connecting pipe (IL2). For example, the ink circulation unit (600) can supply ink (90) to the inkjet head (330) 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 (600) can supply the remainder of the ink (90) remaining after being discharged from the inkjet head (330) through the second connecting pipe (IL2). The flow rate of the ink (90) supplied to the ink circulation unit (600) 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 (600), the variation in the number of bipolar elements (95) contained in the ink (90) discharged from the inkjet head (330) can be minimized.

[0047] The ink circulation unit (600) may be mounted on the first frame (FM1), but is not limited thereto. The ink circulation unit (600) is provided in the inkjet printing device (1000), but its position or shape is not particularly limited. For example, the ink circulation unit (600) may be positioned via a separate device, and if connected to the inkjet head (330), various placements are possible within that range.

[0048] The inkjet head (330) includes an inner tube (331) and a plurality of nozzles (335) and can discharge ink (90) through the nozzles (335). The ink (90) discharged from the nozzles (335) can be sprayed onto a target substrate (SUB) provided on a stage (STA). The nozzles (335) are located on the bottom surface of the inkjet head (330) and can be arranged along one direction in which the inkjet head (330) extends.

[0049] The inner tube (331) is connected to the internal flow path of the first base section (310), and ink (90) can be supplied from the ink circulation section (600). Ink (90) is supplied to the inner tube (331) through the first connecting tube (IL1) connected to the ink circulation section (600), and the ink (90) remaining after being discharged from the nozzle (335) can be supplied to the ink circulation section (600) through the second connecting tube (IL2). The inner tube (331) can be formed along the extension direction of the inkjet head (330). Ink (90) supplied through the inkjet device (300) flows through the inner tube (331) and can be discharged through the nozzle (335) of the inkjet head (330).

[0050] A plurality of nozzles (335) may be located on the lower surface of the inkjet head (330). The plurality of nozzles (335) may be spaced apart from each other and arranged along the extension direction of the inkjet head (330), and connected to an inner tube (331) to discharge ink (90). Although not shown in the drawing, the plurality of nozzles (335) may be arranged in one row or multiple rows. In some embodiments, the number of nozzles (335) included in the inkjet head (330) may be 128 to 1800. The amount of ink (90) ejected through the nozzles (335) may be adjusted according to the voltage applied to each nozzle (335). In one embodiment, the amount of ink (90) discharged once from each nozzle (335) may be 1 to 50 pl (Pico-litter), but is not limited thereto.

[0051] Ink (90) discharged through the nozzle (335) may include a solvent (91) and a bipolar element (95) dispersed in the solvent (91). According to one embodiment, the bipolar element (95) may have a shape that extends in one direction. The bipolar element (95) may be randomly dispersed within the ink (90), flow along the inner tube (331), and then supplied to the nozzle (335). As the bipolar 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 bipolar 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 bipolar element (95). The orientation direction of the bipolar element (95) that extends in one direction may be defined based on the direction in which the first end faces. The bipolar elements (95) flowing within the inner tube (331) and nozzle (335) of the inkjet head (330) may not have a constant orientation direction and may be dispersed in random directions. However, not limited thereto, the bipolar elements (95) may flow within the inner tube (331) and nozzle (335) with a specific orientation direction.

[0052] Ink (90) ejected from the inkjet head (330) is sprayed onto the target substrate (SUB). After the bipolar elements (95) are sprayed onto the target substrate (SUB) with a specific orientation direction, they can be arranged on the target substrate (SUB) with a certain orientation direction by the electric field generated by the electric field generating device (820, 830). That is, the bipolar elements (95) can be aligned in one direction on the target substrate (SUB) by the electric field.

[0053] An inkjet printing device (1000) may include at least one light irradiation device (500; 510, 520). According to one embodiment, the light irradiation device (500) may include a first light irradiation device (510) placed in a first frame (FM1), as in an inkjet device (300), and a second light irradiation device (520) placed between a second frame (FM2) and a third frame (FM3).

[0054] Each frame (FM2~FM4, FM5) may include a first support member (FM_C) and a second support member (FM_R), identical to the first frame (FM1), and may have necessary devices arranged therein. The description regarding the shape and arrangement of each frame (FM2~FM4, FM5) is substantially the same as that described above using the first frame (FM1) as an example; therefore, a detailed description below will be omitted.

[0055] Each light irradiation device (500; 510, 520) includes a second base part and a light irradiation unit.

[0056] The second base portion may have a shape that extends in one direction similar to the first base portion (310) of the inkjet device (300). The second base portion may have a shape that extends in the first direction (DR1) corresponding to the long side of the stage (STA) or target substrate (SUB), for example, the side that extends in the first direction (DR1).

[0057] The light irradiation unit may be disposed in the second base portion. The light irradiation unit may irradiate light onto the upper surface of a target substrate (SUB) disposed on a stage (STA). The manner in which the light irradiation unit is disposed in the second base portion is not particularly limited.

[0058] The type of the light irradiation unit is not particularly limited. In some embodiments, the light irradiation unit may include mercury light, Fe-based metal halide series, Ga-based metal halide series, semiconductor light-emitting elements, etc. However, it is not limited thereto.

[0059] In one embodiment, the first light irradiation device (510) is mounted on the first frame (FM1) together with the inkjet device (300) and can irradiate light simultaneously with the process of spraying ink (90) during the printing process of the bipolar element (95).

[0060] When the stage (STA) passes through the inkjet device (300), light emitted from the first light irradiation device (510) mounted on the first frame (FM1) can be irradiated onto some areas of the target substrate (SUB). Since the first light irradiation device (510) irradiates light only to a certain area while the stage (STA) moves, the primary light irradiation process performed by the first light irradiation device (510) can be performed in a scanning manner according to the movement of the stage (STA).

[0061] Since the first light irradiation device (510) is mounted on the first frame (FM1) together with the inkjet device (300), the area where light is irradiated from the first light irradiation device (510) may be small, and sufficient light may not be irradiated onto the target substrate (SUB). An inkjet printing device (1000) according to one embodiment further includes a second light irradiation device (520) capable of irradiating light over a larger area than the first light irradiation device (510), and a second light irradiation process following the first can be performed in the printing process of the bipolar element (95).

[0062] The second base portion of the second light irradiation device (520) can be mounted on the second frame (FM2) and the third frame (FM3). The stage (STA) that has passed through the first frame (FM1) can then pass through the second frame (FM2) and the third frame (FM3) and pass through the lower part of the second light irradiation device (520). The light irradiation unit of the second light irradiation device (520) may have a larger area than the light irradiation unit of the first light irradiation device (510) so as to cover the entire target substrate (SUB). In the case of the second light irradiation device (520), the stage (STA) irradiates light onto the target substrate (SUB) as it passes through it, but because it has a larger area than the first light irradiation device (510), the time during which light is irradiated onto the target substrate (SUB) may be longer. The second light irradiation device (520) can have a larger area than the target substrate (SUB), so that light can be irradiated to the entire target substrate (SUB) during the second light irradiation process.

[0063] FIG. 7 is a cross-sectional view showing a drying device according to one embodiment. FIG. 8 is a top view showing a drying device according to one embodiment.

[0064] Referring to FIGS. 7 and 8, the drying device (800) of the inkjet printing device (1000) can serve to dry ink sprayed onto a stage (STA). Meanwhile, the drying device (800) may further include an electric field generating device (820, 830) that generates an electric field on the stage (STA).

[0065] The electric field generating device (820, 830) may be located within the drying device (800).

[0066] As described above, the stage (STA) moves in the second direction (DR2) via the first rail (RL1), whereas the electric field generating device (820, 830) may not move along the second direction (DR2). That is, the electric field generating device (820, 830) may be fixedly positioned within the drying device (800). Below, the method of positioning the electric field generating device (820, 830) will be described in more detail.

[0067] The inkjet printing device (1000) may further include a drying device external frame (FM4) located outside the drying device (800). The electric field generating device (820, 830) may be connected to the drying device external frame (FM4). The drying device external frame (FM4) may include a plurality of support members (FM4b, FM4a). The support members (FM4b, FM4a) may include a first support member (FM4b) extended in a first direction (DR1) which is horizontal, and a second support member (FM4a) connected to the first support member (FM4b) and extended in a third direction (DR3) which is vertical. The extension direction of the first support member (FM4b) may be the same as the first direction (DR1) which is the long side direction of the stage (STA). The electric field generating device (820, 830) may be connected to the second support member (FM4a). That is, according to the present embodiment, the electric field generating device (820, 830) may be fixed to the outer frame (FM4) of the drying device and may not move along the first direction (DR1).

[0068] Meanwhile, the drying device (800) may further include a heating plate (840) disposed below the stage (STA). The heating plate (840) can irradiate heat onto the stage (STA). The heating plate (840) can irradiate heat from the lower surface of the stage (STA) and transfer the heat to a target substrate (SUB).

[0069] In this specification, a drying device (800) is exemplified as a device for drying a solvent (91) through heat, including a heating plate (840), but is not limited thereto. The drying device (800) may include various units as a device for drying the solvent (91) of the ink (90). For example, the drying device (800) may include an IR irradiation unit that irradiates infrared light. However, it is not limited thereto.

[0070] The drying device (800) may further include a drying chamber (810) located outside the heating plate (840).

[0071] The above drying chamber (810) can be connected to the outer frame (FM4) of the drying device.

[0072] The drying chamber (810) may be connected to the outer frame (FM4) of the drying device via a fixed shaft (850). The interior of the drying chamber (810) may be maintained at a vacuum level. The fixed shaft (850) may be made of a spring or the like, but is not limited thereto.

[0073] The drying chamber (810) may include a first drying chamber (811) located below the heating plate (840) and a second drying chamber (815) located above the heating plate (840).

[0074] The electric field generating device (820, 830)) may be placed between the first drying chamber (811) and the second drying chamber (815).

[0075] The first electric field generating device (820) may include an electric field connection part (821) connected to the outer frame (FM4) of the drying device and extended into the drying chamber (810), a probe jig (823) connected to the electric field connection part (821) and disposed on the stage (STA), and a probe pad (825) disposed on the lower surface of the probe jig (823).

[0076] The second electric field generating device (830) may include an electric field connection part (831) connected to the outer frame (FM4) of the drying device and extended into the drying chamber (810), a probe jig (833) connected to the electric field connection part (831) and disposed on the stage (STA), and a probe pad (835) disposed on the lower surface of the probe jig (833).

[0077] The drying process may be performed while the stage (STA) remains stationary for a certain period of time at the bottom of the drying device (800).

[0078] Ink (90) sprayed onto a target substrate (SUB) comprises a solvent (91) in which the elements are dispersed, in addition to bipolar elements (95) oriented in one direction. A drying device (800) can remove the solvent (91) of the ink (90), and the bipolar elements (95) can be placed so as to fix their position on the target substrate (SUB). According to one embodiment, in order to prevent the orientation direction and position of the bipolar elements (95) from changing when the solvent (91) is removed, the drying device (800) of the inkjet printing device (1000) further includes the electric field generating device (820, 830) described above, so that the drying process of the solvent (91) can be performed while an electric field (EL) is generated on the target substrate (SUB).

[0079] The electric field generating device (820, 830) can be electrically connected to the target substrate (SUB) to generate an electric field on the target substrate (SUB) placed on the stage (STA). When the electric field generating device (820, 830) and the target substrate (SUB) are electrically connected, an electric field can be generated on the target substrate (SUB) by an electric signal applied from the electric field generating device (820, 830).

[0080] In one embodiment, the electric field generating device (820, 830) may include a first electric field generating device (820) disposed on one side of the stage (STA) and a second electric field generating device (830) disposed on the other side. The first electric field generating device (820) and the second electric field generating device (830) are each connected to the outer frame (FM4) of the drying device and can be electrically connected to a target substrate (SUB) on one side and the other side of the stage (STA), respectively, and can generate an electric field of uniform strength regardless of location, even if the area of ​​the target substrate (SUB) is large.

[0081] The first electric field generating device (820) and the second electric field generating device (830) may each be driven individually or simultaneously with each other.

[0082] The electric field generating device (820, 830) allows the probe jig (823, 833) to move so that the probe pad (825, 835) can be electrically connected to the target substrate (SUB).

[0083] The probe jig (823, 833) is connected to the electric field connection part (821, 831) and can move together with the probe pad (825, 835). In an exemplary embodiment, the probe jig (823, 833) moves along a first direction (DR1), and the probe pad (825, 835) can move along the first direction (DR1) together with the probe jig (823, 833), as well as move to a third direction (DR3).

[0084] That is, the probe pad (825, 835) can be connected to or disconnected from the target substrate (SUB) by driving the probe jig (823, 833).

[0085] The probe jig (823, 833) is connected to the probe pad (825, 835) and can be connected to a separate voltage application device. The probe jig (823, 833) can form an electric field on the target substrate (SUB) by transmitting an electric signal transmitted from the voltage application device to the probe pad (825, 835). The electric signal transmitted to the probe jig (823, 833) may be a voltage for forming an electric field, for example, an alternating current voltage.

[0086] FIG. 9 is a schematic diagram showing the operation of an electric field generating device according to one embodiment.

[0087] The inkjet device (300) can spray ink (90) when an electric field (EL) is generated on a stage (STA) or a target substrate (SUB). As described above, the bipolar element (95) includes a first end and a second end having polarity, and when placed in a predetermined electric field, a dielectrophoretic force is transmitted so that the position or orientation direction may change. The position and orientation direction of a plurality of bipolar elements (95) within the ink (90) sprayed on the target substrate (SUB) may change due to the electric field (EL) generated by the electric field generating device (820, 830). After the printing process of the bipolar element (95) using the inkjet printing device (1000), when the ink (90) is sprayed on the target substrate (SUB), an alignment step of aligning the bipolar elements (95) in one direction may be performed.

[0088] According to an inkjet printing device (1000) according to one embodiment, the inkjet printing device (1000) further includes a drying device external frame (FM4) located outside the drying device (800), and the electric field generating device (820, 830) is connected to the drying device external frame (FM4). Thus, even if a drying process is performed by a heating plate (840) within a drying chamber (810) (at a level of vacuum), the electric field generating device (820, 830) is not directly connected to the drying chamber (810) which is physically deformed by the heat provided by the heating plate (840), thereby minimizing the effect of physical deformation caused by heat. As a result, there is an advantage in that the mis-probing with the stage (STA) (and target substrate (SUB)) of the electric field generating device (820, 830) is minimized.

[0089] Hereinafter, a display device (10) including a light-emitting element (30) manufactured by the inkjet printing device (1000) of FIGS. 1 to 9 will be described.

[0090] FIG. 10 is a schematic plan view of a display device according to one embodiment.

[0091] Referring to FIG. 10, 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).

[0092] 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.

[0093] The shape of the display device (10) can be varied in many ways. For example, the display device (10) may have a shape such as a horizontally elongated rectangle, a vertically elongated rectangle, a square, a rectangle 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. 10, a display device (10) and a display area (DPA) in the shape of a horizontally elongated rectangle are exemplified.

[0094] 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).

[0095] 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.

[0096] 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.

[0097] FIG. 11 is a plan view showing one pixel of a display device according to one embodiment.

[0098] Referring to FIG. 11, 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. 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. Additionally, FIG. 2 illustrates a pixel (PX) including three subpixels (PXn), but is not limited thereto, and the pixel (PX) may include a larger number of subpixels (PXn).

[0099] Each subpixel (PXn) of the display device (10) may include an area defined as a light-emitting region (EMA). The first subpixel (PX1) may include a first light-emitting region (EMA1), the second subpixel (PX2) may include a second light-emitting region (EMA2), and the third subpixel (PX3) may include a third light-emitting region (EMA2). The light-emitting region (EMA) may be defined as an area where a light-emitting element (30) included in the display device (10) is placed and light of a specific wavelength range is emitted. The active layer (36) of the light-emitting element (30) may emit light of a specific wavelength range without directionality, and the light may be emitted in both lateral directions of the light-emitting element (30). The light-emitting region (EMA) may include an area where the light-emitting element (30) is placed, and may include an area where light emitted from the light-emitting element (30) is emitted to an area adjacent to the light-emitting element (30).

[0100] Not limited thereto, the light-emitting region (EMA) 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 the light-emitting region (EMA) may be formed by including the region where they are arranged and the region adjacent thereto.

[0101] Although not shown in the drawing, each subpixel (PXn) of the display device (10) may include a non-emissive region defined as a region other than the emitting region (EMA). The non-emissive region may be a region where the emitting element (30) is not placed and light emitted from the emitting element (30) does not reach, so no light is emitted.

[0102] FIG. 12 is a cross-sectional view taken along the lines IIIa-IIIa', IIIb-IIIb' and IIIc-IIIc' of FIG. 11.

[0103] Referring to FIG. 12 in conjunction with FIG. 11, the display device (10) may include a first substrate (11), a semiconductor layer disposed on the first substrate (11), a plurality of conductive layers, and a plurality of insulating layers.

[0104] Specifically, the first substrate (11) may be an insulating substrate. The first substrate (11) may be made of an insulating material such as glass, quartz, or polymer resin. Additionally, the first substrate (11) may be a rigid substrate, but may also be a flexible substrate capable of bending, folding, rolling, etc.

[0105] The light-blocking layers (BML1, BML2) may be disposed on the first substrate (11). The first light-blocking layer (BML1) and the second light-blocking layer (BML2) of the light-blocking layers (BML1, BML2) are disposed to overlap at least with the active material layers (DT_ACT, ST_ACT) of the driving transistor (DT) and the switching transistor (ST), respectively. The light-blocking layers (BML1, BML2) may include a material that blocks light, thereby preventing light from being incident on the active material layers (DT_ACT, ST_ACT) of each transistor. As an example, the first and second light-blocking layers (BML1, BML2) may be formed of an opaque metallic material that blocks the transmission of light. However, they are not limited thereto, and in some cases, the light-blocking layers (BML1, BML2) may be omitted, or only the first light-blocking layer (BML1) may be included.

[0106] The buffer layer (12) may be disposed over the entire surface of the first substrate (11), including light-blocking layers (BML1, BML2). The buffer layer (12) is formed on the first substrate (11) to protect the transistors (DT, ST) of the pixel (PX) from moisture penetrating through the first 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 (SiON) are alternately stacked.

[0107] The semiconductor layer is disposed on the buffer layer (12). The semiconductor layer may include a first active material layer (DT_ACT) of the driving transistor (DT) and a second active material layer (ST_ACT) of the switching transistor (ST). These may be disposed to partially overlap with the gate electrodes (DT_G, ST_G), etc. of the first gate conductive layer described later.

[0108] In an exemplary embodiment, the semiconductor layer may include polycrystalline silicon, single-crystal silicon, oxide semiconductor, etc. Polycrystalline silicon may be formed by crystallizing amorphous silicon. When the semiconductor layer includes polycrystalline silicon, the first active material layer (DT_ACT) may include a plurality of doped regions (DT_ACTa, DT_ACTb) that are also doped with impurities and a channel region (DT_ACTc) between them. The second active material layer (ST_ACT) may also include a plurality of doped regions (ST_ACTa, ST_ACTb) and a channel region (ST_ACTc) between them.

[0109] In another exemplary embodiment, the semiconductor layer may include an oxide semiconductor. In this case, the doping region of each active material layer (DT_ACT, ST_ACT) may be a conductive region. The oxide semiconductor may be an oxide semiconductor containing indium (In). In some embodiments, 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. However, it is not limited thereto.

[0110] The first gate insulating layer (13) is disposed on the semiconductor layer and the buffer layer (12). The first gate insulating layer (13) may be disposed on the buffer layer (12) by including a semiconductor layer. The first gate insulating layer (13) may function as a gate insulating film for each transistor (DT, ST). 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 (SiON), or may be formed in a stacked structure.

[0111] The first gate conductive layer is disposed on the first gate insulating layer (13). The first gate conductive layer may include a first gate electrode (DT_G) of a driving transistor (DT) and a second gate electrode (ST_G) of a switching transistor (ST). The first gate electrode (DT_G) may be disposed to overlap in the thickness direction with the first channel region (DT_ACTc) of the first active material layer (DT_ACT), and the second gate electrode (ST_G) may be disposed to overlap in the thickness direction with the second channel region (ST_ACTc) of the second active material layer (ST_ACT). 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.

[0112] The first protective layer (15) is disposed on the first gate conductive layer. The first protective layer (15) is disposed to cover the first gate conductive layer and can perform the function of protecting it. The first protective layer (15) may be composed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiON), or may be formed in a stacked structure.

[0113] A second gate conductive layer is disposed on the first protective layer (15). The second gate conductive layer may include a first capacitance electrode (CE1) of a storage capacitor disposed such that at least a portion of the area overlaps with the first gate electrode (DT_G) in the thickness direction. The first capacitance electrode (CE1) overlaps with the first gate electrode (DT_G) in the thickness direction with the first protective layer (15) in between, and a storage capacitor may be formed between them. The second 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.

[0114] The first interlayer insulating layer (17) is disposed on the second gate conductive layer. The first interlayer insulating layer (17) can function as an insulating film between the second gate conductive layer and other layers disposed thereon. The first interlayer insulating layer (17) may be composed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiON), or may be formed in a stacked structure.

[0115] The first data conductive layer is disposed on the first interlayer insulating layer (17). The first data conductive layer may include a first source / drain electrode (DT_SD1) and a second source / drain electrode (DT_SD2) of a driving transistor (DT), and a first source / drain electrode (ST_SD1) and a second source / drain electrode (ST_SD2) of a switching transistor (ST).

[0116] The source / drain electrodes (DT_SD1, DT_SD2) of the driving transistor (DT) can each be in contact with the doping regions (DT_ACTa, DT_ACTb) of the first active material layer (DT_ACT) through a contact hole penetrating the first interlayer insulating layer (17) and the first gate insulating layer (13). The source / drain electrodes (ST_SD1, ST_SD2) of the switching transistor (ST) can each be in contact with the doping regions (ST_ACTa, ST_ACTb) of the second active material layer (ST_ACT) through a contact hole penetrating the first interlayer insulating layer (17) and the first gate insulating layer (13). Additionally, the first source / drain electrode (DT_SD1) of the driving transistor (DT) and the first source / drain electrode (ST_SD1) of the switching transistor (ST) can be electrically connected to the first light-blocking layer (BML1) and the second light-blocking layer (BML2), respectively, through another contact hole.

[0117] 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.

[0118] The second interlayer insulating layer (18) may be disposed on the first data conductive layer. The second interlayer insulating layer (18) covers the first data conductive layer and is disposed entirely on the first interlayer insulating layer (17), and can perform the function of protecting the first data conductive layer. The second interlayer insulating layer (18) may be composed of an inorganic layer including inorganic materials, such as silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), or may be formed in a stacked structure.

[0119] The second data conductive layer is disposed on the second interlayer insulating layer (18). 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 driving transistor (DT) 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).

[0120] The first conductive pattern (CDP) can be electrically connected to the first source / drain electrode (DT_SD1) of the driving transistor (DT) through a contact hole formed in the second interlayer insulating layer (18). The first conductive pattern (CDP) also contacts the first electrode (21) described later, and the driving transistor (DT) can transmit the first power supply voltage applied from the first voltage line (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 line (VL2) and one first voltage line (VL1), it is not limited thereto. The second data conductive layer may include a larger number of first voltage lines (VL1) and second voltage lines (VL2).

[0121] 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.

[0122] The first flattening layer (19) is disposed on the second data conductive layer. The first flattening layer (19) may include an organic insulating material, such as polyimide (PI), and may perform a surface flattening function.

[0123] A plurality of first banks (40), a plurality of electrodes (21, 22), a light-emitting element (30), a second bank (45), and a plurality of contact electrodes (26, 27) are disposed on the first flattening layer (19). Additionally, a plurality of insulating layers (51, 52, 53, 54) may be further disposed on the first flattening layer (19).

[0124] A plurality of first banks (40) may be placed directly on the first flattening layer (19). A plurality of first banks (40) may be spaced apart at the boundary between subpixels (PXn) so as not to extend into other subpixels (PXn) adjacent to the second direction (DR2) within each subpixel (PXn). Additionally, a plurality of first banks (40) may be arranged to be spaced apart from each other in the first direction (DR1). A plurality of first banks (40) may be spaced apart from each other to form an area where a light-emitting element (30) is placed between them. A plurality of first banks (40) may be arranged for each subpixel (PXn) to form a linear pattern in the display area (DPA) of the display device (10). Although two first banks (40) are shown in the drawing, they are not limited thereto. Depending on the number of electrodes (21, 22) described later, more first banks (40) may be placed.

[0125] The first bank (40) 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 bank (40) may have an inclined side, and light emitted from the light-emitting element (30) may proceed toward the inclined side of the first bank (40). The electrodes (21, 22) placed on the first bank (40) may include a material with high reflectivity, and light emitted from the light-emitting element (30) may be reflected from the electrodes (21, 22) placed on the side of the first bank (40) and emitted toward the upper direction of the first flattening layer (19). That is, the first bank (40) may provide an area where the light-emitting element (30) is placed, and at the same time, perform the function of a reflective barrier that reflects light emitted from the light-emitting element (30) toward the upper direction. The side of the first bank (40) may be inclined in a linear shape, but is not limited thereto, and the first bank (40) may have a curved outer surface in the shape of a semicircle or semi-ellipse. In an exemplary embodiment, the first banks (40) may include an organic insulating material such as polyimide (PI), but are not limited thereto.

[0126] A plurality of electrodes (21, 22) are disposed on the first bank (40) and the 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 they may be disposed to be spaced apart from each other in a first direction (DR1). The first electrode (21) and the second electrode (22) may have a shape substantially similar to the first bank (40), but may have a shape with a longer length in the second direction (DR2) than the first bank (40).

[0127] The first electrode (21) and the second electrode (22) each extend in a second direction (DR2) within a subpixel (PXn), but may be spaced apart from other electrodes (21, 22) at the boundary with another subpixel (PXn) adjacent in the second direction (DR2). In some embodiments, a second bank (45) is placed at the boundary of each subpixel (PXn), and electrodes (21, 22) placed in each subpixel (PXn) adjacent in the second direction (DR2) may be spaced apart in the portion overlapping with the second bank (45). However, this is not limited thereto, and some electrodes (21, 22) may be placed extending beyond the subpixel (PXn) adjacent in the second direction (DR2) without being separated for each subpixel (PXn).

[0128] The first electrode (21) can be electrically connected to a driving transistor (DT) through a first contact hole (CT1) at the boundary with a subpixel (PXn) adjacent in the second direction (DR2). For example, the first electrode (21) may be positioned so that at least a portion of it overlaps with a portion extending in the first direction (DR1) of the second bank (45) and may be in contact with a first conductive pattern (CDP) through a first contact hole (CT1) penetrating the first flattening layer (19). The second electrode (22) can be electrically connected to a second voltage wiring (VL2) through a second contact hole (CT2) at the boundary with a subpixel (PXn) adjacent in the second direction (DR2). For example, the second electrode (22) may be positioned to overlap with the portion extending in the first direction (DR1) of the second bank (45) and may contact the second voltage wiring (VL2) through a second contact hole (CT2) penetrating the first flattening layer (19). However, it is not limited thereto. In some embodiments, the first contact hole (CT1) and the second contact hole (CT2) may be positioned within the area enclosed by the second bank (45) so as not to overlap with the second bank (45).

[0129] In the drawings, one first electrode (21) and one second electrode (22) are exemplified for each subpixel (PXn), but are not limited thereto. In some embodiments, the number of first electrodes (21) and second electrodes (22) occupied for each subpixel (PXn) may be greater. Additionally, the first electrode (21) and the second electrode (22) occupied 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 occupied 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 occupied so that it surrounds the other electrode. The structure or shape in which the first electrode (21) and the second electrode (22) are occupied is not particularly limited, provided that at least some regions of the first electrode (21) and the second electrode (22) are spaced apart from each other and face each other, thereby forming a region between them where a light-emitting element (30) is to be placed.

[0130] 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. For example, the plurality of electrodes (21, 22) are electrically connected to the light-emitting elements (30) through contact electrodes (26, 27) described later, and an electrical signal applied to the electrodes (21, 22) can be transmitted to the light-emitting elements (30) through the contact electrodes (26, 27).

[0131] In an exemplary embodiment, either the first electrode (21) or 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 may also be true.

[0132] 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 the electric field formed on the first electrode (21) and the second electrode (22). When using the inkjet printing device (1000) described above, ink containing the light-emitting element (30) is sprayed onto each electrode (21, 22), and an electric field generating device (820, 830) may be electrically connected to each electrode (21, 22) to generate an electric field (EL) above it. The light-emitting element (30) dispersed in the ink may be aligned on the electrode (21, 22) by receiving a dielectrophoretic force from the electric field (EL) generated on the electrode (21, 22).

[0133] The first electrode (21) and the second electrode (22) may each be placed on the first bank (40). The first electrode (21) and the second electrode (22) may be spaced apart in the first direction (DR1), and a plurality of light-emitting elements (30) may be placed between them. The light-emitting elements (30) may be placed between the first electrode (21) and the second electrode (22), and at the same time, at least one end of each may be electrically connected to the first electrode (21) and the second electrode (22).

[0134] In some embodiments, the first electrode (21) and the second electrode (22) may each be formed to have a width greater than that of the first bank (40). For example, the first electrode (21) and the second electrode (22) may each be positioned to cover the outer surface of the first bank (40). The first electrode (21) and the second electrode (22) are each positioned on the side of the first bank (40), and the gap between the first electrode (21) and the second electrode (22) may be narrower than the gap between the first bank (40). Additionally, at least some portions of the first electrode (21) and the second electrode (22) may be positioned directly on the first flattening layer (19).

[0135] Each electrode (21, 22) may 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., but is not limited thereto. In some embodiments, 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), aluminum (Al), etc. as a highly reflective material. In this case, each electrode (21, 22) may reflect light emitted from the light-emitting element (30) and traveling toward the side of the first bank (40) toward the upper direction of each subpixel (PXn).

[0136] Not limited thereto, 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. In an exemplary embodiment, each electrode (21, 22) may have a stacked structure such as ITO / silver (Ag) / ITO / , ITO / Ag / IZO, or ITO / Ag / ITZO / IZO, or may be an alloy including aluminum (Al), nickel (Ni), lanthanum (La), etc.

[0137] A first insulating layer (51) is disposed on the first flattening layer (19), the first electrode (21), and the second electrode (22). The first insulating layer (51) is disposed to partially cover the first electrode (21) and the second electrode (22), including the area between them. For example, the first insulating layer (51) may be disposed to cover most of the upper surfaces of the first electrode (21) and the second electrode (22), while exposing a portion of the first electrode (21) and the second electrode (22). In other words, the first insulating layer (51) may be formed substantially over the first flattening layer (19) and may include an opening (not shown) that partially exposes the first electrode (21) and the second electrode (22).

[0138] In an exemplary embodiment, the first insulating layer (51) may have a step formed such that a portion of the upper surface is recessed between the first electrode (21) and the second electrode (22). However, it is not limited thereto. The first insulating layer (51) may have a flat upper surface so that the light-emitting element (30) is placed thereon.

[0139] The first insulating layer (51) can protect the first electrode (21) and the second electrode (22) while simultaneously insulating them from each other. Additionally, it can prevent the light-emitting element (30) disposed on the first insulating layer (51) from being damaged by direct contact with other components. However, the shape and structure of the first insulating layer (51) are not limited thereto.

[0140] The second bank (45) may be placed on the first insulating layer (51). The second bank (45) may be placed at the boundary between each subpixel (PXn) and surrounding the area where the first banks (40) are placed on the first insulating layer (51). The second bank (45) may be arranged to have a shape extending in the first direction (DR1) and the second direction (DR2) to form a grid pattern across the entire front of the display area (DPA). The portion of the second bank (45) extending in the first direction (DR1) may partially overlap with the first electrode (21) and the second electrode (22), while the portion extending in the second direction (DR2) may be spaced apart from the plurality of first banks (40) and the first electrode (21) and the second electrode (22).

[0141] According to one embodiment, the height of the second bank (45) may be greater than the height of the first bank (40). Unlike the first bank (40), the second bank (45) can perform the function of distinguishing neighboring subpixels (PXn) and simultaneously preventing ink from overflowing into adjacent subpixels (PXn) during the inkjet printing process of the manufacturing process of the display device (10). The second bank (45) can separate the ink in which different light-emitting elements (30) are dispersed for each different subpixel (PXn) so that they do not mix with each other. The second bank (45) may include polyimide (PI) as in the first bank (40), but is not limited thereto.

[0142] A light-emitting element (30) may be placed on each electrode (21, 22). A plurality of light-emitting elements (30) may be spaced apart from each other and may be aligned substantially parallel to each other. The spacing between the light-emitting elements (30) is not particularly limited. In some cases, a plurality of light-emitting elements (30) may be placed adjacently to form a group, while other plurality of light-emitting elements (30) may be placed at a certain distance apart to form a group, or they may be placed with an uneven density. Additionally, the direction in which each electrode (21, 22) extends and the direction in which the light-emitting element (30) extends may be substantially perpendicular. However, this is not limited thereto, and the light-emitting element (30) may be placed obliquely rather than perpendicular to the direction in which each electrode (21, 22) extends.

[0143] A light-emitting element (30) may include an active layer (36) containing different materials to emit light of different wavelength ranges to the outside. A display device (10) may include light-emitting elements (30) that emit light of different wavelength ranges. For example, the light-emitting element (30) of the first subpixel (PX1) may include an active layer (36) that emits light of a first color with a central wavelength band of a first wavelength, the light-emitting element (30) of the second subpixel (PX2) may include an active layer (36) that emits light of a second color with a central wavelength band of a second wavelength, and the light-emitting element (30) of the third subpixel (PX3) may include an active layer (36) that emits light of a third color with a central wavelength band of a third wavelength. 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, it is not limited thereto. In some cases, each subpixel (PXn) may include the same type of light-emitting element (30) and emit light of substantially the same color.

[0144] A light-emitting element (30) may be placed on a first insulating layer (51) between the first banks (40) or between each electrode (21, 22). For example, the light-emitting element (30) may be placed such that at least one end is placed on the first electrode (21) or the second electrode (22). The extended length of the light-emitting element (30) is longer than the distance 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. However, it is not limited thereto, and only one end of the light-emitting element (30) may be placed on the electrode (21, 22), or both ends may not be placed on the electrode (21, 22). Even if the light-emitting element (30) is not placed on the electrodes (21, 22), both ends can be electrically connected to each electrode (21, 22) through the contact electrodes (26, 27) described later.

[0145] A plurality of layers of the light-emitting element (30) may be arranged in a direction perpendicular to the upper surface of the first substrate (11) or the first flattening layer (19). The light-emitting element (30) of the display device (10) may be arranged such that one extended direction is parallel to 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, it is not limited thereto. In some cases, if the light-emitting element (30) has a different structure, a plurality of layers may be arranged in a direction perpendicular to the first flattening layer (19).

[0146] Additionally, both ends of the light-emitting element (30) may each come into contact with contact electrodes (26, 27). According to one embodiment, since the insulating film (38) is not formed on the extended one-way end surface of the light-emitting element (30) and a portion of the semiconductor layer is exposed, the exposed semiconductor layer may come into contact with the contact electrodes (26, 27). However, this is not limited thereto. In some cases, at least a portion of the insulating film (38) of the light-emitting element (30) may be removed, and the insulating film (38) may be removed so that the sides of both ends of the semiconductor layers are partially exposed. The sides of the exposed semiconductor layer may come into direct contact with the contact electrodes (26, 27).

[0147] The second insulating layer (52) may be partially disposed on the light-emitting element (30) positioned between the first electrode (21) and the second electrode (22). The second insulating layer (52) may be positioned to partially wrap the outer surface of the light-emitting element (30). The portion of the second insulating layer (52) positioned on the light-emitting element (30) may have a shape that extends in a second direction (DR2) between the first electrode (21) and the second electrode (22) in a planar shape. For example, the second insulating layer (52) may form a linear or island pattern within each subpixel (PXn).

[0148] The second insulating layer (52) is disposed on the light-emitting element (30) and may expose one end and the other end of the light-emitting element (30). The second insulating layer (52) may perform the function of protecting the light-emitting element (30) and simultaneously fixing the light-emitting element (30) during the manufacturing process of the display device (10). In addition, in an exemplary embodiment, some of the material of the second insulating layer (52) may be disposed between the lower surface of the light-emitting element (30) and the first insulating layer (51). As described above, the second insulating layer (52) may be formed to fill the space between the first insulating layer (51) and the light-emitting element (30) formed during the manufacturing process of the display device (10). Accordingly, the second insulating layer (52) may be disposed to surround the outer surface of the light-emitting element (30) to protect the light-emitting element (30) and simultaneously fix the light-emitting element (30) during the manufacturing process of the display device (10).

[0149] A plurality of contact electrodes (26, 27) and a third insulating layer (53) may be disposed on the second insulating layer (52).

[0150] A plurality of contact electrodes (26, 27) may have a shape that extends in one direction. Each of the plurality of contact electrodes (26, 27) may contact the light-emitting element (30) and the electrodes (21, 22). The first contact electrode (26) and the second contact electrode (27) of the contact electrodes (26, 27) may each be placed on a part of the first electrode (21) and the second electrode (22). The first contact electrode (26) is placed on the first electrode (21), and the second contact electrode (27) is placed on the second electrode (22), and the first contact electrode (26) and the second contact electrode (27) may each have a shape that extends in a second direction (DR2). The first contact electrode (26) and the second contact electrode (27) may be spaced apart from each other in a first direction (DR1), and they may form a stripe-shaped pattern within the light-emitting region (EMA) of each subpixel (PXn).

[0151] In some embodiments, the width of the first contact electrode (26) and the second contact electrode (27) measured in one direction may be equal to or smaller than the width of the first electrode (21) and the second electrode (22) measured in one direction, respectively. The first contact electrode (26) and the second contact electrode (27) may be positioned to cover a portion of the exposed upper surface of the first electrode (21) and the second electrode (22) while simultaneously contacting one end and the other end of the light-emitting element (30), respectively. As described above, the upper surface of the first electrode (21) and the second electrode (22) is exposed, and the exposed upper surface may come into contact with each contact electrode (26, 27).

[0152] As described above, the light-emitting element (30) has a semiconductor layer exposed on both end surfaces in the extended direction, and the first contact electrode (26) and the second contact electrode (27) can contact the light-emitting element (30) on the end surface where the semiconductor layer is exposed. One end of the light-emitting element (30) can be electrically connected to the first electrode (21) through the first contact electrode (26), and the other end can be electrically connected to the second electrode (22) through the second contact electrode (27).

[0153] In the drawing, a first contact electrode (26) and a second contact electrode (27) are shown disposed in one subpixel (PXn), but are not limited thereto. The number of first contact electrodes (26) and second contact electrodes (27) may vary depending on the number of first electrodes (21) and second electrodes (22) disposed in each subpixel (PXn).

[0154] A third insulating layer (53) is disposed on the first contact electrode (26). The third insulating layer (53) can electrically insulate the first contact electrode (26) and the second contact electrode (27) from each other. The third insulating layer (53) is disposed to cover the first contact electrode (26), but may not be disposed on the other end of the light-emitting element (30) so that the light-emitting element (30) can contact the second contact electrode (27). The third insulating layer (53) may partially contact the first contact electrode (26) and the second insulating layer (52) on the upper surface of the second insulating layer (52). The side of the third insulating layer (53) in the direction in which the second electrode (22) is disposed may be aligned with one side of the second insulating layer (52). Additionally, the third insulating layer (53) may also be disposed on a non-luminous region, such as on the first insulating layer (51) disposed on the first flattening layer (19). However, it is not limited thereto.

[0155] The second contact electrode (27) is disposed on the second electrode (22), the second insulating layer (52), and the third insulating layer (53). The second contact electrode (27) can come into contact with the other end of the light-emitting element (30) and the exposed upper surface of the second electrode (22). The other end of the light-emitting element (30) can be electrically connected to the second electrode (22) through the second contact electrode (27).

[0156] That is, the first contact electrode (26) is disposed between the first electrode (21) and the third insulating layer (53), and the second contact electrode (27) may be disposed on the third insulating layer (53). The second contact electrode (27) may partially contact the second insulating layer (52), the third insulating layer (53), the second electrode (22), and the light-emitting element (30). One end of the second contact electrode (27) may be disposed on the third insulating layer (53). The first contact electrode (26) and the second contact electrode (27) may be kept out of contact with each other by the second insulating layer (52) and the third insulating layer (53). However, this is not limited thereto, and in some cases, the third insulating layer (53) may be omitted.

[0157] The contact electrodes (26, 27) may include a conductive material. For example, they may include ITO, IZO, ITZO, aluminum (Al), etc. As an example, the contact electrodes (26, 27) may include a transparent conductive material, and light emitted from the light-emitting element (30) may pass through the contact electrodes (26, 27) and proceed toward the electrodes (21, 22). Each electrode (21, 22) may include a material with high reflectivity, and the electrodes (21, 22) placed on the inclined side of the first bank (40) may reflect the incident light toward the upper direction of the first substrate (11). However, they are not limited thereto.

[0158] The fourth insulating layer (54) can be placed over the entire surface of the first substrate (11). The fourth insulating layer (54) can function to protect the external environment of the members placed on the first substrate (11).

[0159] Each of the above-described first insulating layer (51), second insulating layer (52), third insulating layer (53), and fourth insulating layer (54) may include an inorganic insulating material or an organic insulating material. In an exemplary embodiment, the first insulating layer (51), second insulating layer (52), third insulating layer (53), and fourth insulating layer (54) may include an inorganic insulating material such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (Al2O3), 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.

[0160] An inkjet printing device (1000) can spray a light-emitting element (30) onto the electrodes (21, 22) of a display device (10) through an inkjet device (300). Additionally, an electric field generating device (820, 830) can be electrically connected to each electrode (21, 22) to generate an electric field (EL) on them, and the light-emitting element (30) can be aligned on the electrodes (21, 22) by the electric field (EL). According to one embodiment, a display device (10) can be manufactured by printing a light-emitting element (30) placed on the electrodes (21, 22) using an inkjet printing device (1000).

[0161] 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

[0162] 10: Display device 30: Light-emitting element 90: Ink 95: Bipolar element 300: Inkjet device 500: Light irradiation device 800: Drying device 900: Inspection device 1000: Inkjet printing device

Claims

Claim 1 An inkjet printing device comprising: a stage moving in a first direction; an inkjet device for spraying ink onto the stage; a drying device for drying the ink sprayed onto the stage; and a drying device external frame located outside the drying device, wherein the drying device comprises an electric field generating device for generating an electric field on the stage and a drying chamber connected to the drying device external frame, wherein the electric field generating device comprises an electric field connection part connected to the drying device external frame and extending into the drying chamber, a probe jig connected to the electric field connection part and disposed on the stage, and a probe pad disposed on the lower surface of the probe jig. Claim 2 In claim 1, the electric field generating device is an inkjet printing device located within the drying device. Claim 3 In claim 1, the electric field generating device is an inkjet printing device that does not move along the first direction. Claim 4 delete Claim 5 delete Claim 6 In claim 1, the electric field generating device is an inkjet printing device that is fixed to the outer frame of the drying device and does not move along the first direction. Claim 7 In claim 1, the drying device further comprises a heating plate disposed at the bottom of the stage, an inkjet printing device. Claim 8 In claim 7, the heating plate is an inkjet printing device that irradiates heat onto the stage. Claim 9 In claim 7, the drying chamber is an inkjet printing device located outside the heating plate. Claim 10 delete Claim 11 In claim 1, the drying chamber is an inkjet printing device connected to the outer frame of the drying device through a fixed shaft. Claim 12 In claim 9, the inkjet printing device comprises a drying chamber including a first drying chamber located below the heating plate and a second drying chamber located above the heating plate. Claim 13 In claim 12, the electric field generating device is an inkjet printing device disposed between the first drying chamber and the second drying chamber. Claim 14 delete Claim 15 An inkjet printing device comprising: a stage moving in a first direction; an inkjet device for spraying ink onto the stage; a light irradiation device for irradiating light onto the stage; a drying device for drying the ink sprayed onto the stage; and a drying device external frame located outside the drying device, wherein the inkjet device, the light irradiation device, and the drying device are arranged in a line along the first direction, and the drying device comprises an electric field generating device for generating an electric field on the stage, and a drying chamber connected to the drying device external frame, wherein the electric field generating device comprises an electric field connection part connected to the drying device external frame and extending into the drying chamber, a probe jig connected to the electric field connection part and disposed on the stage, and a probe pad disposed on the lower surface of the probe jig. Claim 16 In claim 15, the electric field generating device is an inkjet printing device located within the drying device. Claim 17 In claim 15, the electric field generating device is an inkjet printing device that does not move along the first direction. Claim 18 delete Claim 19 delete Claim 20 In claim 15, the electric field generating device is an inkjet printing device that is fixed to the outer frame of the drying device and does not move along the first direction.

Images