Inkjet printing device, bipolar element printing method and display device manufacturing method

Abstract

An inkjet printing device, a method for printing a bipolar element, and a method for manufacturing a display device are provided. The inkjet printing device includes: a stage; an inkjet head disposed above the stage and including a plurality of nozzles, through which ink including bipolar elements is discharged, each of the bipolar elements having partial regions doped to have different polarities; an actuator disposed in the inkjet head to adjust the amount of droplets of ink discharged through the nozzle; and at least one sensing unit disposed in the inkjet head to measure the number of bipolar elements discharged through the nozzle.

Description

Technical Field

[0001] The present disclosure relates to an inkjet printing device, a method for printing a bipolar element, and a method for manufacturing a display device. Background Art

[0002] As multimedia technology develops, the importance of display devices has been increasing. In response to this, various types of display devices, such as organic light emitting displays, liquid crystal displays (LCDs), and the like, have been used.

[0003] The display device is a device for displaying an image, and includes a display panel, such as an organic light-emitting display panel or a liquid crystal display panel. The light-emitting display panel may include a light-emitting element, such as a light-emitting diode (LED), and examples of the light-emitting diode include an organic light-emitting diode (OLED) using an organic material as a fluorescent material and an inorganic light-emitting diode using an inorganic material as a fluorescent material. Summary of the invention

[0004] [Technical issues]

[0005] Aspects of the present disclosure provide an inkjet printing apparatus that includes a consistent number of bipolar elements per unit droplet of discharged ink.

[0006] Aspects of the present disclosure also provide a method for printing a bipolar element capable of keeping the number of bipolar elements dispersed in a unit droplet constant using an inkjet printing device, and a method for manufacturing a display device including a light emitting element.

[0007] It should be noted that aspects of the present disclosure are not limited thereto, and other aspects not mentioned herein will be apparent to those of ordinary skill in the art from the following description.

[0008] [Technical solution]

[0009] According to an embodiment of the present disclosure, an inkjet printing device includes: a stage; an inkjet head positioned above the stage and including a plurality of nozzles, through which ink including a bipolar element is discharged, the bipolar element having regions doped to have different polarities; an actuator disposed in the inkjet head and regulating droplets of ink discharged from the nozzle; and at least one sensing unit disposed in the inkjet head and measuring the number of bipolar elements discharged through the nozzle.

[0010] The inkjet head may include a base portion, a discharge portion connected to the base portion and having a plurality of nozzles disposed therein, and an inner tube to which ink is supplied, and the ink may be supplied to and flow in the inner tube and discharged through the nozzles.

[0011] The sensing unit may include a first sensing part and a second sensing part, wherein the first sensing part measures a magnetic field generated in the ink according to the movement of the bipolar element, and the second sensing part transmits a signal related to the number of bipolar elements calculated by the magnetic field measured by the first sensing part to the actuator.

[0012] The actuator may receive a signal related to the number of bipolar elements measured by the sensing unit and adjust a droplet of ink discharged from the nozzle.

[0013] The sensing unit may be provided at an inlet of the inner tube to which the ink is supplied.

[0014] The inlet of the inner tube may have a smaller diameter at a portion where the sensing unit is provided than at other portions.

[0015] The inkjet printing apparatus may further include a sub-actuator disposed in the inkjet head and adjusting a diameter of an inner tube in which the ink flows, wherein the sub-actuator may increase a flow speed of the ink flowing in the inner tube.

[0016] The sensing unit may be disposed between the inlet of the inner tube and the nozzle.

[0017] The sensing unit may be provided in the discharge portion.

[0018] The sensing unit may further include a light emitting part that irradiates the bipolar element with light.

[0019] The base portion of the inkjet head may be made of a transparent material.

[0020] According to an embodiment of the present disclosure, a method for printing bipolar elements includes: preparing an ink in which a plurality of bipolar elements are dispersed, and supplying the ink to an inkjet head; measuring the number of bipolar elements in the discharged ink while discharging the ink from the inkjet head; and when the number of bipolar elements in the ink exceeds a reference set value, adjusting droplets of ink discharged from the inkjet head.

[0021] The measurement of the number of bipolar elements may be performed by at least one sensing unit provided in the inkjet head, and the sensing unit may measure a magnetic field generated in the ink according to the movement of the bipolar element.

[0022] Adjusting the discharged droplets of ink may include: sensing a change in the number of bipolar elements by a sensing unit; and adjusting the discharged droplets of ink per unit process according to the change in the number of bipolar elements.

[0023] The ink discharged from the inkjet head may be ejected onto a target substrate, and the method for printing the bipolar element may further include positioning the bipolar element on the target substrate.

[0024] A plurality of regions may be defined on a target substrate, and droplets of ink may be adjusted according to the variation in the number of bipolar elements so that the number of bipolar elements ejected into the plurality of regions is consistent.

[0025] Measuring the number of bipolar elements in the discharged ink while discharging the ink can be performed using an inkjet printing device, and the inkjet printing device can include: a stage; an inkjet head positioned above the stage and including a plurality of nozzles, ink including bipolar elements having regions doped to have different polarities being discharged through the nozzles; an actuator disposed in the inkjet head and regulating droplets of ink discharged from the nozzles; and at least one sensing unit that measures the number of bipolar elements discharged through the nozzles.

[0026] The actuator may adjust the droplets of ink discharged from the nozzle according to the change in the number of bipolar elements measured by the sensing unit.

[0027] According to an embodiment of the present disclosure, a method for manufacturing a display device includes: preparing a target substrate, the target substrate including a plurality of regions divided from each other and having a first electrode and a second electrode formed in the plurality of regions; spraying ink into the plurality of regions while controlling droplets of ink according to the number of light-emitting elements dispersed in the ink; and placing the light-emitting elements on the first electrode and the second electrode.

[0028] Jetting ink may include: measuring the number of light emitting elements in the jetted ink; and when the number of light emitting elements in the jetted ink exceeds a reference set value, controlling the number of light emitting elements by adjusting droplets of ink jetted into a plurality of regions.

[0029] The light emitting element may include a first semiconductor layer doped to have a first polarity, a second semiconductor layer doped to have a second polarity different from the first polarity, and an active layer disposed between the first semiconductor layer and the second semiconductor layer.

[0030] Measuring the number of light emitting elements in the ejected ink may include measuring a magnetic field generated in the ink according to movement of the light emitting elements.

[0031] Details of other implementations are included in the detailed description and accompanying drawings.

[0032] [Beneficial Effects]

[0033] The inkjet printing device according to the embodiment includes a sensing unit capable of measuring the number of bipolar elements in the discharged ink. The sensing unit can measure the number of bipolar elements included in each unit volume of the ink flowing in the inkjet head by various methods. In addition, the sensing unit can sense the change in the number of bipolar elements while discharging the ink, and can feed back the sensed change to adjust the droplets of the ink discharged from the nozzle, thereby controlling the number of bipolar elements ejected onto the target substrate.

[0034] Therefore, in the method for printing bipolar elements using an inkjet printing device according to an embodiment, the number of bipolar elements discharged into a unit space can be kept consistent, and in a display device including a light-emitting element manufactured using the inkjet printing device, the light-emitting reliability of each pixel can be improved.

[0035] The effects according to the embodiments are not limited to the above-exemplified contents, and more various effects are included in the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a perspective view of an inkjet printing device according to an embodiment.

[0037] Figure 2 is a schematic top view of a print head unit according to an embodiment.

[0038] Figure 3 is a schematic diagram illustrating the operation of the print head unit according to the embodiment.

[0039] Figure 4 is a schematic diagram illustrating an ink circulation unit and a print head unit according to an embodiment.

[0040] Figure 5 is a schematic cross-sectional view of an inkjet head according to an embodiment.

[0041] Figure 6 yes Figure 5 An enlarged view of part A of FIG.

[0042] Figure 7 is a schematic diagram illustrating that ink discharged from an inkjet head is ejected onto a target substrate according to an embodiment.

[0043] Figure 8 is a schematic diagram showing changes in the number of bipolar elements flowing in an inkjet head.

[0044] Fig. 9 is a schematic diagram showing a change in the amount of ink discharged from an inkjet head according to an embodiment.

[0045] Fig.10 is a schematic plan view of a probe device according to an embodiment.

[0046] Fig.11 and Fig.12 is a schematic diagram illustrating the operation of the probe unit according to the embodiment.

[0047] Fig.13 is a schematic diagram illustrating generation of an electric field on a target substrate by a probe device according to an embodiment.

[0048] Fig.14 is a flow chart illustrating a method for printing a bipolar element according to an embodiment.

[0049] Figures 15 to 22 is a view illustrating a method for printing a bipolar element using an inkjet printing apparatus according to an embodiment.

[0050] Fig.23 and Fig.24 is a cross-sectional view of an inkjet head according to another embodiment.

[0051] Fig.25 is a cross-sectional view illustrating that a sensing unit detects the number of bipolar elements according to another embodiment.

[0052] Fig.26 is a cross-sectional view illustrating that a sensing unit detects the number of bipolar elements according to another embodiment.

[0053] Fig. 27 and Fig.28 is a cross-sectional view showing part of an inkjet head according to another embodiment.

[0054] Fig.29 is a cross-sectional view illustrating that a sensing unit detects the number of bipolar elements according to another embodiment.

[0055] Fig.30 is a schematic diagram of a light emitting element according to an embodiment.

[0056] Fig.31 is a schematic plan view of a display device according to an embodiment.

[0057] Fig.32 is a plan view showing one pixel of a display device according to an embodiment.

[0058] Fig.33 It is along Fig.32 Cross-sectional views taken along line Xa-Xa', line Xb-Xb' and line Xc-Xc'.

[0059] Figure 34 to Figure 36 are cross-sectional views illustrating some processes of a method for manufacturing a display device according to an embodiment.

[0060] Fig.37 and Fig.38 is a schematic diagram of a light emitting element according to another embodiment. DETAILED DESCRIPTION

[0061] Hereinafter, the present invention will be described more fully with reference to the accompanying drawings in which preferred embodiments of the present invention are shown. However, the present invention may be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0062] It will also be understood that when a layer is referred to as being 'on' another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. The same reference numerals refer to the same components throughout the specification.

[0063] It will be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the teachings of the present invention, the first element discussed below may be referred to as the second element. Similarly, the second element may also be referred to as the first element.

[0064] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0065] Figure 1 is a perspective view of an inkjet printing device according to an embodiment. Figure 2 is a schematic top view of a print head unit according to an embodiment. Figure 3 is a schematic diagram illustrating the operation of the print head unit according to the embodiment. Figure 4 is a schematic diagram illustrating an ink circulation unit and a print head unit according to an embodiment. Figure 3 The shapes of the print head unit 100 and the probe device 700 provided on the stage STA according to the embodiment when viewed from a front view are shown.

[0066] refer to Figures 1 to 4 The inkjet printing apparatus 1000 according to the embodiment includes a printing head unit 100 including a plurality of inkjet heads 300. The inkjet printing apparatus 1000 may further include a stage STA, an ink circulation unit 500, a probe device 700, and a base frame 600.

[0067] exist Figure 1In the figure, 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 directions disposed on the same plane and perpendicular to each other, and the third direction DR3 is a direction perpendicular to each of the first direction DR1 and the second direction DR2. It can be understood that the first direction DR1 represents a lateral direction in the drawings, the second direction DR2 represents a longitudinal direction in the drawings, and the third direction DR3 represents an upward or downward direction in the drawings.

[0068] The inkjet printing device 1000 may eject a predetermined ink 90 onto a target substrate SUB using the print head unit 100. An electric field may be generated on the target substrate SUB on which the ink 90 is ejected by the probe device 700, and particles such as bipolar elements 95 included in the ink 90 may be aligned on the target substrate SUB.

[0069] The target substrate SUB may be disposed on the probe device 700, the probe device 700 may form an electric field on the target substrate SUB, and the electric field may be transferred to the ink 90 ejected onto the target substrate SUB. Particles such as the bipolar element 95 included in the ink 90 may have a shape in which they extend in one direction, and may be aligned by the electric field so that the direction in which they extend points to one direction.

[0070] The inkjet printing apparatus 1000 according to the embodiment may include an inkjet head 300 and a sensing unit 400 (see FIG. 1 ) provided in the inkjet head 300. Figure 5 ). The inkjet head 300 may eject, discharge or print the ink 90 including the bipolar elements 95 on the target substrate SUB, and the sensing unit 400 may detect the number of bipolar elements 95 in the ink 90 printed or discharged from the inkjet head 300. The inkjet printing device 1000 may sense a change in the number of bipolar elements 95 in the discharged ink 90, and may feed back the sensed change to the inkjet head 300 to adjust the droplets discharged from the inkjet head 300 so as to keep the number of bipolar elements 95 discharged in a unit space consistent. Hereinafter, the inkjet printing device 1000 will be described in detail with reference to the accompanying drawings.

[0071] The stage STA may provide an area on which the probe device 700 is disposed. The inkjet printing apparatus 1000 includes a first rail RL1 and a second rail RL2 extending in the second direction DR2, and the stage STA is disposed on the first rail RL1 and the second rail RL2. The stage STA may move in the second direction DR2 on the first rail RL1 and the second rail RL2 by a separate moving member. The probe device 700 may move in the second direction DR2 together with the stage STA, and when the probe device 700 passes through the print head unit 100, the ink 90 may be ejected onto the probe device 700. However, the present disclosure is not limited thereto. A structure in which the stage STA moves has been shown in the drawings, but in some embodiments, the stage STA may be fixed and the print head unit 100 may be movable. In this case, the print head unit 100 may be mounted on a frame disposed on the first rail RL1 and the second rail RL2.

[0072] The print head unit 100 may include a plurality of inkjet heads 300 and may be disposed on the base frame 600. The print head unit 100 may eject predetermined ink 90 onto a target substrate SUB disposed on the probe device 700 using the inkjet heads 300 connected to individual ink storage portions.

[0073] The base frame 600 may include a support portion 610 and a moving unit 630. The support portion 610 may include a first support portion 611 extending in a first direction DR1 (which is a horizontal direction), and a second support portion 612 connected to the first support portion 611 and extending in a third direction DR3 (which is a vertical direction). The extension direction of the first support portion 611 may be the same as the first direction DR1, which is a long side direction of the probe device 700. The print head unit 100 may be disposed on the moving unit 630 mounted on the first support portion 611.

[0074] The moving unit 630 may include a moving portion 631 and a fixed portion 632, wherein the moving portion 631 is installed on the first supporting portion 611 and can move in one direction, the fixed portion 632 is provided on the lower surface of the moving portion 631 and the print head unit 100 is provided on the fixed portion 632. The moving portion 631 may move in the first direction DR1 on the first supporting portion 611, and the print head unit 100 may be fixed to the fixed portion 632 and move in the first direction DR1 together with the moving portion 631.

[0075] The print head unit 100 may be disposed on the base frame 600, and may eject the ink 90 provided from the ink reservoir onto the target substrate SUB through the inkjet head 300. The print head unit 100 may be spaced apart by a specific interval from the stage STA passing through the base frame 600 below the base frame 600. The interval at which the print head unit 100 is spaced apart from the stage STA may be adjusted by the height of the second support portion 612 of the base frame 600. The distance between the print head unit 100 and the stage STA spaced apart from each other may be adjusted within a range in which the print head unit 100 has a specific interval with the target substrate SUB when the probe device 700 and the target substrate SUB are disposed on the stage STA, thereby ensuring a space required for the printing process.

[0076] According to an embodiment, the print head unit 100 may include a plurality of nozzles 350 (see Figure 5 ) of the printing head unit 100. The inkjet head 300 may be disposed on a lower surface of a main body portion of the printing head unit 100.

[0077] A plurality of inkjet heads 300 may be arranged to be spaced apart from each other in one direction, and may be arranged in one or more rows. It has been shown in the drawings that the inkjet heads 300 are arranged in two rows, and the inkjet heads 300 of the corresponding rows are arranged to be misaligned with each other. However, the present disclosure is not limited thereto, and the inkjet heads 300 may be arranged in a greater number of rows, and may be arranged to overlap each other, rather than misaligned with each other. The shape of the inkjet head 300 is not particularly limited, but as an example, the inkjet head 300 may have a rectangular shape.

[0078] At least one inkjet head 300 (for example, two inkjet heads 300) may form a group to be arranged adjacent to each other. However, the number of inkjet heads 300 included in one group is not limited thereto, and for example, the number of inkjet heads 300 included in one group may be 1 to 5. In addition, it has been shown in the drawings that only six inkjet heads 300 are arranged in the print head unit 100, but this is for schematically illustrating the print head unit 100, and the number of inkjet heads 300 is not limited thereto.

[0079] The inkjet head 300 disposed in the print head unit 100 may eject ink 90 onto a target substrate SUB disposed on the stage STA. According to an embodiment, the print head unit 100 may move in one direction on the first supporting portion 611, and the inkjet head 300 may move in one direction to eject ink 90 onto the target substrate SUB.

[0080] The print head unit 100 may move in a first direction DR1 in which the first supporting portion 611 extends, and the inkjet head 300 may eject the ink 90 onto the target substrate SUB while moving in the first direction DR1.

[0081] In an embodiment, the ink 90 may include a solvent 91 and a plurality of bipolar elements 95 included in the solvent 91. In an embodiment, the ink 90 may be provided in a solution or colloid state. For example, the solvent 91 may be acetone, water, alcohol, toluene, propylene glycol (PG) or propylene glycol methyl acetate (PGMA), triethylene glycol monobutyl ether (TGBE), diethylene glycol monophenyl ether (DGPE), an amide-based solvent, a dicarbonyl-based solvent, diethylene glycol dibenzoate, a tricarbonyl-based solvent, triethyl citrate, a phthalate-based solvent, benzyl butyl phthalate, bis (2-ethylhexyl) phthalate, bis (2-ethylhexyl) isophthalate, ethyl phthaloyl glycolate, etc., but is not limited thereto. A plurality of bipolar elements 95 may be included in a state where they are dispersed in the solvent 91, and the plurality of bipolar elements 95 may be supplied to and discharged from the print head unit 100.

[0082] 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 may eject the ink 90 onto the entire target substrate SUB while moving along the first direction DR1. In addition, when a plurality of target substrates SUB are disposed on the probe device 700, the print head unit 100 may eject the ink 90 onto each of the plurality of target substrates SUB while moving along the first direction DR1.

[0083] However, the present disclosure is not limited thereto, and the print head unit 100 may be positioned outside the first rail RL1 and the second rail RL2, and then may move in the first direction DR1 and eject the ink 90 onto the target substrate SUB. When the stage STA moves in the second direction DR2 to be positioned below the base frame 600, the print head unit 100 may move between the first rail RL1 and the second rail RL2, and eject the ink 90 through the inkjet head 300. The operation of such an inkjet head 300 is not limited thereto, and may be variously modified as long as it can implement a similar process.

[0084] The inkjet printing apparatus 1000 may further include an ink circulation unit 500. The ink circulation unit 500 may supply the ink 90 to the printing head unit 100, and the inkjet head 300 may discharge the supplied ink 90. ​​The ink 90 may circulate between the ink circulation unit 500 and the inkjet head 300, and some of the ink 90 supplied to the inkjet head 300 may be discharged from the inkjet head 300, and the remaining portion of the ink 90 may be supplied to the ink circulation unit 500 again.

[0085] The ink circulation unit 500 may be connected to the inkjet head 300 through the first connection pipe IL1 and the second connection pipe IL2. For example, the ink circulation unit 500 may supply the ink 90 to the inkjet head 300 through the first connection pipe IL1, and the flow rate of the supplied ink 90 may be adjusted by the first valve VA1. In addition, the remaining portion of the ink 90 remaining after being discharged from the inkjet head 300 may be supplied to the ink circulation unit 500 through the second connection pipe IL2. The flow rate of the ink 90 supplied to the ink circulation unit 500 through the second connection pipe IL2 may be adjusted by the second valve VA2. When the ink 90 circulates through the ink circulation unit 500, the deviation of the number of bipolar elements 95 included in the ink 90 discharged from the inkjet head 300 may be minimized.

[0086] 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 apparatus 1000, but its position or shape is not particularly limited. For example, the ink circulation unit 500 may be provided by a separate device and may be provided differently as long as it is connected to the inkjet head 300.

[0087] In some embodiments, the ink circulation unit 500 may include a first ink storage part 510, a second ink storage part 520, a third ink storage part 530, a pressure pump 550, a compressor 560, and a flow meter 580. In the ink circulation unit 500, the second ink storage part 520, the pressure pump 550, and the third ink storage part 530 may be connected to the inkjet head 300, and may form an ink circulation system.

[0088] First ink storage part 510 may be a storage part in which manufactured ink 90 is prepared. Ink 90 including solvent 91 and bipolar element 95 may be prepared in first ink storage part 510 of ink circulation unit 500 and may be supplied to the ink circulation system.

[0089] The second ink storage portion 520 may be connected to the first ink storage portion 510 to be supplied with the prepared ink 90. ​​In addition, the ink 90 remaining after being discharged from the inkjet head 300 may be supplied to the second ink storage portion 520 through the second connection pipe IL2. The second ink storage portion 520 may be positioned between the third ink storage portion 530 and the inkjet head 300 and between the third ink storage portion 530 and the first ink storage portion 510 to configure an ink circulation system. When the second ink storage portion 520 is omitted, an excess of ink 90 may be supplied to the third ink storage portion 530, so that the bipolar element 95 cannot be smoothly dispersed. The ink circulation unit 500 may further include the second ink storage portion 520 to prevent an excess of ink 90 from being supplied to the third ink storage portion 530. As an example, the second ink storage portion 520 may be used as a buffer storage portion in which some of the ink 90 circulating in the ink circulation system is stored.

[0090] The ink 90 supplied to the second ink storage portion 520 may be supplied to the third ink storage portion 530 via a pressure pump 550. The pressure pump 550 may be a pump that transmits power to a fluid so that the ink 90 in the ink circulation system may circulate. The ink 90 supplied to the second ink storage portion 520 may be supplied to the third ink storage portion 530 by the pressure pump 550. The flow meter 580 may be provided between the pressure pump 550 and the third ink storage portion 530, and may measure a flow rate of the ink 90 supplied to the third ink storage portion 530. The pressure pump 550 may adjust the flow rate of the ink 90 supplied to the third ink storage portion 530 according to the flow rate of the ink 90 measured by the flow meter 580.

[0091] In addition, the ink circulation unit 500 may further include a compressor 560, and the compressor 560 may adjust the pressure in the third ink storage portion 530. The compressor 560 may remove gas from the third ink storage portion 530 so that the interior of the third ink storage portion 530 becomes a vacuum state, or may introduce an external inert gas into the third ink storage portion 530 so that the third ink storage portion 530 has a predetermined pressure. However, the present disclosure is not limited thereto, and the compressor 560 of the ink circulation unit 500 may also be omitted.

[0092] The third ink storage part 530 may be connected to the second ink storage part 520 through the pressure pump 550 to be supplied with the ink 90. ​​In addition, the third ink storage part 530 may supply the ink 90 to the inkjet head 300 through the first connection pipe IL1. In an embodiment, the third ink storage part 530 may include an agitator ST, and the agitator ST may disperse the bipolar element 95 in the ink 90. ​​The ink 90 supplied to the third ink storage part 530 may maintain a state in which the bipolar element 95 does not sink and is dispersed as the agitator ST rotates. That is, the agitator ST of the third ink storage part 530 may prevent the bipolar element 95 from sinking to the lower part of the third ink storage part 530 so that the number of bipolar elements 95 in the ink 90 discharged by the inkjet head 300 is reduced. The third ink storage part 530 may supply the ink 90 in which the bipolar element 95 is smoothly dispersed to the inkjet head 300, and the inkjet head 300 may discharge the ink 90 including the predetermined number or more of the bipolar elements 95.

[0093] Meanwhile, in the inkjet printing apparatus 1000, the unit droplet of the ink 90 discharged from the inkjet head 300 needs to be constant, and the number of bipolar elements 95 dispersed in the unit droplet needs to be controlled to be consistent. When the ink 90 is discharged from the inkjet head 300 through the ink circulation system, when the number of bipolar elements 95 per unit droplet of the ink 90 is inconsistent, the reliability of the inkjet printing apparatus 1000 may be problematic. According to an embodiment, the inkjet printing apparatus 1000 may include at least one sensing unit 400 (see FIG. 4 ) disposed in the inkjet head 300. Figure 5 ), and the number of bipolar elements 95 in the ink 90 discharged from the inkjet head 300 can be measured. The inkjet printing device 1000 can sense the change in the number of bipolar elements 95 in the ink 90, and feed the sensed change back to the inkjet head 300 to keep the number of bipolar elements 95 discharged to the unit space consistent. Hereinafter, the inkjet head 300 and the sensing unit 400 will be described in more detail.

[0094] Figure 5 is a schematic cross-sectional view of an inkjet head according to an embodiment.

[0095] refer to Figure 5 , the inkjet head 300 may include a plurality of nozzles 350 and eject ink 90 through the nozzles 350. The ink 90 discharged from the nozzles 350 may be ejected onto a target substrate SUB disposed on the stage STA or the probe device 700. The nozzles 350 may be disposed on a bottom surface of the inkjet head 300 and may be arranged along one direction in which the inkjet head 300 extends.

[0096] The inkjet head 300 may include a base portion 310, an inner tube 330, and a plurality of nozzles 350. The inkjet head 300 may further include a discharge portion 370 and an actuator 390. In some embodiments, a sensing unit 400 may be provided in the inkjet head 300.

[0097] The base portion 310 may constitute a main body of the inkjet head 300. The base portion 310 may be attached to the print head unit 100. The base portion 310 may have a shape in which it extends in the first direction DR1 and the second direction DR2, as described above with reference to FIG. Figure 2 However, the present disclosure is not limited thereto, and the base portion 310 may also have a circular or polygonal shape.

[0098] The discharge portion 370 may be a portion of the base portion 310 of the inkjet head 300 in which the nozzle 350 is disposed. In the drawings, it has been shown that a discharge portion 370 connected to the base portion 310 and a plurality of discharge portions 370 spaced apart from the discharge portion 370 are provided, and the nozzle 350 is formed between these discharge portions 370. However, in essence, the discharge portions 370 are not spaced apart from each other and may be a single integral member, and the nozzle 350 may be formed in the shape of a hole passing through the discharge portion 370. That is, the plurality of discharge portions 370 are not spaced apart from each other and may be formed as a single member. However, the present disclosure is not limited thereto, and in some embodiments, the inkjet head 300 may also include a plurality of units including a discharge portion 370 in which the nozzle 350 is formed. In this case, the plurality of discharge portions 370 may be spaced apart from each other and connected to the base portion 310.

[0099] The inner tube 330 may be provided in the base portion 310 and connected to the internal flow path of the print head unit 100, and the ink 90 may be supplied from the ink circulation unit 500 to the inner tube 330. The ink 90 may be supplied to the print head unit 100 through the first connection tube IL1 connected to the ink circulation unit 500, and the ink 90 remaining after being discharged from the nozzle 350 may be supplied to the ink circulation unit 500 through the second connection tube IL2. The ink 90 may be supplied to the inner tube 330 of the inkjet head 300 at the inlet 331 of the inner tube 330 connected to the internal flow path of the print head unit 100, and the ink 90 remaining after being discharged may leave to the internal flow path through the outlet 333 of the inner tube 330.

[0100] In addition, the inkjet head 300 may include a filter F disposed in the inner tube 330. When the ink 90 flowing along the inner tube 330 is introduced into the nozzle 350, the filter F may prevent materials other than the solvent 91 and the bipolar element 95 from being introduced into the nozzle 350. Therefore, the nozzle 350 may be prevented from being clogged with foreign matter or foreign matter may be prevented from being mixed into the ink 90 discharged from the nozzle 350.

[0101] The base portion 310 may have a shape extending in one direction, and the inner tube 330 may be formed along the extending direction of the base portion 310. The ink 90 supplied through the print head unit 100 may flow through the inner tube 330 and then may be discharged through the nozzle 350 of the inkjet head 300.

[0102] A plurality of nozzles 350 may be disposed at a discharge portion 370 positioned on one surface (e.g., lower surface) of the base portion 310. The plurality of nozzles 350 may be spaced apart from each other and arranged along the extension direction of the base portion 310, and may pass through the discharge portion 370, which may be regarded as a part of the base portion 310, and be connected to the inner tube 330 to discharge the ink 90. ​​Although not shown in the drawings, the plurality of nozzles 350 may be arranged in one or more rows. In addition, four nozzles 350 are formed in the inkjet head 300, but the present disclosure is 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 may discharge the ink 90 introduced along the inner tube 330. The amount of the ink 90 ejected by the nozzle 350 may be adjusted according to the voltage applied to each nozzle 350. In an embodiment, the amount of the ink 90 discharged from each nozzle 350 at one time may be 1 to 50 pl (microliters), but is not limited thereto.

[0103] According to an embodiment, the nozzle 350 may include an inlet 351 and an outlet 353. The inlet 351 may be a portion through which the ink 90 directly connected to the inner tube 330 and flowing along the inner tube 330 is supplied to the nozzle 350. The outlet 353 may be a portion through which the ink 90 connected to the inlet 351 and supplied from the inlet 351 is discharged from the nozzle 350. Meanwhile, the inlet 351 and the outlet 353 of the nozzle 350 may have the same diameter, but are not limited thereto. The diameters of the inlet 351 and the outlet 353 of the nozzle 350 may be different from each other according to the shape of the discharge portion 370. By including portions separated from each other, the discharge portion 370 may have different shapes according to the diameter of the nozzle 350.

[0104] The ink 90 discharged through the nozzle 350 may include a solvent 91 and a bipolar element 95 dispersed in the solvent 91. According to an embodiment, the bipolar element 95 may have a shape in which it extends in one direction. The bipolar element 95 may be randomly dispersed in the ink 90, flow along the inner tube 330, and then be supplied to the nozzle 350. Since the bipolar element 95 has a shape in which it extends in one direction, the orientation direction of the bipolar element 95 may be the direction in which the long axis points. In addition, the bipolar element 95 may include parts with different polarities. For example, 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 the two ends of the bipolar element 95 in the long axis direction. The orientation direction of the bipolar element 95 extending in one direction may be defined based on the direction in which the first end points. The bipolar element 95 flowing in the inner tube 330 and the nozzle 350 of the inkjet head 300 may be dispersed in a random orientation direction rather than a constant orientation direction. However, the present disclosure is not limited thereto, and bipolar elements 95 may flow in inner tube 330 and nozzle 350 in a state in which they have a specific orientation direction.

[0105] The actuator 390 may be provided at the discharge portion 370 which may be regarded as a part of the base portion 310. The actuator 390 may be provided to surround the nozzle 350. The actuator 390 may apply hydraulic pressure to the ink 90 introduced into the nozzle 350 so that the ink 90 may 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 provided to correspond to the nozzle 350 and to surround the nozzle 350, and may be provided to be spaced apart from other actuators 390 by an interval at which the nozzles 350 are spaced apart from each other.

[0106] According to an embodiment, the actuator 390 may control the amount of ink 90 discharged through the nozzle 350. The actuator 390 may adjust the hydraulic pressure applied to the ink 90, and may adjust the droplets of the ink 90 discharged to the unit space during the printing process of the inkjet printing device 1000. For example, the amount of ink 90 discharged from the nozzle 350 at one time may be 1 to 50 pl (pico liters), and the discharge amount of the ink 90 required for the unit space in one printing process may be 50 pl or more. In this case, the actuator 390 may control the droplets of the ink 90 discharged from the nozzle 350 differently in one printing process by adjusting the strength, frequency, etc. of the hydraulic pressure.

[0107] A plurality of bipolar elements 95 are dispersed in ink 90 discharged from inkjet head 300. Ink 90 discharged from nozzle 350 at one time may include a specific number of bipolar elements 95 according to the degree of dispersion of bipolar elements 95. However, bipolar elements 95 may include a material having a relatively high specific gravity, and in an ink circulation system composed of inkjet head 300 and ink circulation unit 500, bipolar elements 95 may sink in ink 90. ​​Therefore, the dispersion degree of bipolar elements 95 in ink 90 cannot be kept constant, and the number of bipolar elements 95 in ink 90 discharged at one time may vary.

[0108] According to an embodiment, inkjet printing apparatus 1000 may include a sensing unit 400 capable of measuring the number of bipolar elements 95 included in ink 90 discharged from nozzle 350. Sensing unit 400 may sense the number of bipolar elements 95 discharged from nozzle 350 per unit time or a change in the number of bipolar elements 95, and may feed back the sensed number or the sensed change to actuator 390 to transmit a feedback signal to actuator 390. Actuator 390 may sense the feedback signal received from sensing unit 400 to adjust the droplet of ink 90 discharged from nozzle 350 per unit time or during a unit process. Inkjet printing apparatus 1000 may include sensing unit 400 and actuator 390 so as to keep the number of bipolar elements 95 discharged from inkjet head 300 consistent during a printing process.

[0109] The sensing unit 400 may be provided in the inkjet head 300. The sensing unit 400 may measure the number of bipolar elements 95 in the ink 90 discharged from the nozzle 350. For example, the sensing unit 400 may be provided at the base portion 310 of the inkjet head 300, and may be provided at the inlet 331 of the inner tube 330 through which the ink 90 is introduced. In some embodiments, the sensing unit 400 may be provided in a form in which it is inserted into the base portion 310 of the inkjet head 300. However, the present disclosure is not limited thereto, and the sensing unit 400 may be provided at another position within the inkjet head 300.

[0110] The sensing unit 400 may include a first sensing portion 410 and a second sensing portion 420. The first sensing portion 410 and the second sensing portion 420 may be disposed to be spaced apart from each other, with a space (e.g., an inlet 331 of the inner tube 330) in which the ink 90 flows therebetween. The first sensing portion 410 and the second sensing portion 420 may be inserted into the base portion 310 and disposed to contact the outer wall of the inner tube 330, but are not limited thereto. The first sensing portion 410 and the second sensing portion 420 may be disposed to be spaced apart from the outer wall of the space through which the ink 90 flows.

[0111] The first sensing portion 410 and the second sensing portion 420 can measure the number of bipolar elements 95 in the unit space or unit volume of the ink 90. ​​The first sensing portion 410 and the second sensing portion 420 can generate or receive a specific signal for measuring the number of bipolar elements 95 in the ink 90, and thus can measure the number of bipolar elements 95.

[0112] The method for sensing unit 400 to measure the number of bipolar elements 95 may be modified variously. As an example, sensing unit 400 may measure the number of bipolar elements 95 included in a unit volume by taking an image of ink 90 flowing in inner tube 330. In this case, first sensing portion 410 may be an image taking portion for taking an image of ink 90, and second sensing portion 420 may be a processing portion for measuring the number of bipolar elements 95 per unit volume through the image taken by first sensing portion 410.

[0113] Figure 6 yes Figure 5 An enlarged view of part A of FIG. Figure 7 is a schematic diagram illustrating that ink discharged from an inkjet head is ejected onto a target substrate according to an embodiment.

[0114] refer to Figure 6 and Figure 7 , while referring to Figure 5 , the first sensing portion 410 of the sensing unit 400 may capture an image of the ink 90 flowing in the inlet 331 of the inner tube 330 and transfer the captured image to the second sensing portion 420. The second sensing portion 420 may calculate or count the number of bipolar elements 95 in the ink 90 based on the image. The sensing unit 400 disposed adjacent to the inlet 331 of the inner tube 330 may measure the number of bipolar elements 95 per unit droplet of the ink 90 discharged from the nozzle 350 of the inkjet head 300 by the number of bipolar elements 95 measured at the inlet 331.

[0115] The ink 90 discharged from the inkjet head 300 is ejected onto the target substrate SUB. The target substrate SUB may be a substrate providing a space on which the bipolar element 95 is printed using the inkjet printing device 1000. The ink 90 and the bipolar element 95 discharged from the inkjet head 300 may be disposed on the target substrate SUB. The sensing unit 400 may measure the number of bipolar elements 95 included in the ink 90 flowing in the inkjet head 300, and may know the number of bipolar elements 95 disposed on the target substrate SUB through the droplets of the ink 90 discharged from the nozzles 350. For example, the ink 90 discharged from any one nozzle 350 of the inkjet head 300 in the printing process may be positioned in a predetermined area separated on the target substrate SUB. Inkjet printing apparatus 1000 may measure the number of bipolar elements 95 positioned in a predetermined area on target substrate SUB through the number of bipolar elements 95 in ink 90 measured by sensing unit 400 and droplets of ink 90 discharged from nozzle 350 by actuator 390 per unit process time.

[0116] During the printing process in which the inkjet head 300 discharges the ink 90, the ink 90 may be continuously circulated between the inkjet head 300 and the ink circulation unit 500. In this process, the bipolar element 95 having a large specific gravity may sink in the ink 90, and the number of bipolar elements 95 per unit volume or unit flow rate of the ink 90 introduced into the inner tube 330 of the inkjet head 300 may be reduced. In this case, when the droplets of the ink 90 discharged from the nozzle 350 by the actuator 390 per unit time or per unit process are constant, the number of bipolar elements 95 positioned in a predetermined area on the target substrate SUB may be reduced.

[0117] Figure 8 is a schematic diagram showing changes in the number of bipolar elements flowing in an inkjet head.

[0118] refer to Figure 8, the sensing unit 400 may sense a change in the number of bipolar elements 95 in the ink 90 introduced into the inkjet head 300. When an image is captured by the first sensing portion 410, the second sensing portion 420' may sense a change in the number of bipolar elements 95 in the ink 90 through a change in the captured image. When the number of bipolar elements 95 per unit volume or unit flow rate of the ink 90 introduced into the inner tube 330 is reduced, the number of bipolar elements 95 discharged from the nozzle 350 may also be reduced. For example, when the bipolar elements 95 sink in the ink circulation system composed of the ink circulation unit 500 and the inkjet head 300, the number of bipolar elements 95 in the ink 90 introduced from the ink circulation unit 500 may be reduced. However, the present disclosure is not limited thereto, and there may be various reasons causing the number of bipolar elements 95 to change. The inkjet printing apparatus 1000 may include a greater number of sensing units 400 to provide accurate feedback on the change in the number of bipolar elements 95. Inkjet printing apparatus 1000 may maintain the number of bipolar elements 95 in ink 90 discharged from inkjet head 300 to be consistent through feedback provided from sensing unit 400 .

[0119] Sensing unit 400 can measure the number of bipolar elements 95 in discharged ink 90 while inkjet printing device 1000 discharges ink 90, and can sense the dispersion and changes in the number of bipolar elements 95 per unit droplet of ink 90 during the printing process. When the number of bipolar elements 95 exceeds a reference set value, sensing unit 400 can feed back the change in the number of bipolar elements 95 to actuator 390 in real time to transmit a feedback signal to actuator 390.

[0120] According to an embodiment, in inkjet printing apparatus 1000, sensing unit 400 may sense a change in the number of bipolar elements 95 in ink 90 introduced into inkjet head 300 during a printing process, and transmit a feedback signal based on the sensed change to actuator 390. Actuator 390 may adjust droplets of ink 90 discharged from nozzle 350 based on the feedback signal so that the number of bipolar elements 95 discharged per unit time or per unit process is constant.

[0121] Fig. 9 is a schematic diagram showing a change in the amount of ink discharged from an inkjet head according to an embodiment.

[0122] Combination Figure 7 refer to Fig. 9, the actuator 390 of the inkjet head 300 may control the droplets of the ink 90 discharged per unit time or per unit process based on the feedback signal transmitted from the sensing unit 400. For example, when the sensing unit 400 senses a change in the number of bipolar elements 95, the actuator 390 may adjust the hydraulic pressure transmitted to the ink 90, etc., to adjust the droplets of the ink 90 discharged from the nozzle 350 at one time, or to adjust the droplets or the number of droplets discharged from the nozzle 350 per unit time. Therefore, even if the number of bipolar elements 95 introduced into the inkjet head 300 during the printing process is reduced, the number of bipolar elements 95 disposed on the target substrate SUB during the unit process may be kept consistent. Specifically, when the target substrate SUB includes a plurality of regions that are evenly divided, the inkjet printing apparatus 1000 may discharge a constant number of bipolar elements 95 for each region.

[0123] Inkjet printing apparatus 1000 according to an embodiment may include sensing unit 400 and actuator 390 to sense a change in the number of bipolar elements 95, and may adjust the droplets of ink 90 discharged from nozzle 350 per unit process in response to the sensed change. Therefore, inkjet printing apparatus 1000 may print or eject a consistent number of bipolar elements 95 in a predetermined area. As described later, inkjet printing apparatus 1000 may minimize an error in the number of bipolar elements 95 for each area of ​​an apparatus including bipolar elements 95, and may improve the reliability of a product.

[0124] Meanwhile, the bipolar element 95 may be ejected onto the target substrate SUB while having a specific orientation direction, and then be positioned on the target substrate SUB while having a constant orientation direction by the electric field generated by the probe device 700. That is, the bipolar element 95 may be aligned in one direction on the target substrate SUB by the electric field generated by the probe device 700. Hereinafter, the probe device 700 will be described with reference to other drawings.

[0125] Fig.10 is a schematic plan view of a probe device according to an embodiment.

[0126] refer to Figure 1 and Fig.10 , the probe device 700 may include a sub-stage 710 , a probe support 730 , a probe unit 750 , and an aligner 780 .

[0127] The probe device 700 may be disposed on the stage STA and may move in the second direction DR2 together with the stage STA. The ink 90 may be ejected onto the probe device 700 on which the target substrate SUB is disposed while the stage STA moves. When the ink 90 is ejected, the probe device 700 may generate an electric field on the target substrate SUB. However, the present disclosure is not limited thereto. In some embodiments, the stage STA does not move, and the print head unit 100 may eject the ink 90 onto the stage STA while moving along the second direction DR2.

[0128] The sub-stage 710 may provide a space in which the target substrate SUB is disposed. In addition, the probe support 730, the probe unit 750, and the aligner 780 may be disposed on the sub-stage 710. The shape of the sub-stage 710 is not particularly limited, and as an example, as shown in the figure, the sub-stage 710 may be in a rectangular shape having two pairs of side edges extending in the first direction DR1 and the second direction DR2. The sub-stage 710 may include a long side extending in the second direction DR2 and a short side extending in the first direction DR1. However, the overall shape of the sub-stage 710 in the plan view may vary according to the shape of the target substrate SUB in the plan view. For example, when the target substrate SUB has a rectangular shape in the plan view, the sub-stage 710 may have a rectangular shape as shown in the figure, and when the target substrate SUB has a circular shape in the plan view, the sub-stage 710 may also have a circular shape in the plan view. However, the present disclosure is not limited thereto, and the sub-stage 710 and the target substrate SUB may also have different shapes.

[0129] At least one aligner 780 may be disposed on the sub-stage 710. The aligner 780 may be disposed on each side of the sub-stage 710, and an area surrounded by a plurality of aligners 780 may be an area in which the target substrate SUB is disposed. It has been shown in the drawings that two aligners 780 are disposed to be spaced apart from each other on each side of the sub-stage 710, and a total of eight aligners 780 are disposed on the sub-stage 710. However, the present disclosure is not limited thereto, and the number, arrangement, etc. of the aligners 780 may vary according to the shape or type of the target substrate SUB.

[0130] The probe support 730 and the probe unit 750 are disposed on the sub-stage 710. The probe support 730 may provide a space in which the probe unit 750 is disposed on the sub-stage 710. Specifically, the probe support 730 may be disposed on at least one side of the sub-stage 710 and may extend along a direction in which one side portion extends. As an example, Figure 1As shown in , the probe support 730 may be arranged to extend in the second direction DR2 on the left and right portions of the sub-stage 710. However, the present disclosure is not limited thereto, and a greater number of probe supports 730 may be included, and in some cases, the probe supports 730 may also be arranged on the upper and lower sides of the sub-stage 710. That is, the structure of the probe support 730 may vary according to the number, arrangement, structure, etc. of the probe units 750 included in the probe device 700.

[0131] The probe unit 750 may be disposed on the probe support 730 to form an electric field on the target substrate SUB prepared on the sub-stage 710. The probe unit 750 may extend in one direction (e.g., in the second direction DR2) like the probe support 730, and the extension length of the probe unit 750 may involve the entire target substrate SUB. That is, the size and shape of the probe support 730 and the probe unit 750 may vary according to the target substrate SUB.

[0132] In an implementation, the probe unit 750 may include a probe driver 753 disposed on the probe support 730, a probe fixture 751 disposed on the probe driver 753 and receiving an electrical signal, and a probe pad 758 connected to the probe fixture 751 and transferring the electrical signal to the target substrate SUB.

[0133] The probe driver 753 may be provided on the probe support 730 to move the probe fixture 751 and the probe pad 758. In an embodiment, the probe driver 753 may move the probe fixture 751 in the horizontal direction and the vertical direction, for example, in the first direction DR1 (which is the horizontal direction) and the third direction DR3 (which is the vertical direction). The probe pad 758 may be connected to or disconnected from the target substrate SUB by driving the probe driver 753. In the process of the inkjet printing device 1000, in the step of forming an electric field in the target substrate SUB, the probe driver 753 may be driven to connect the probe pad 758 to the target substrate SUB, and in other steps, the probe driver 753 may be driven again to disconnect the probe pad 758 from the target substrate SUB. This will be described in detail below with reference to other drawings.

[0134] The probe pad 758 may form an electric field on the target substrate SUB by an electric signal transmitted from the probe fixture 751. The probe pad 758 may be connected to the target substrate SUB, and may transmit an electric signal to the target substrate SUB to form an electric field on the target substrate SUB. As an example, the probe pad 758 may be in contact with an electrode, a power supply pad, etc. of the target substrate SUB, and the electric signal of the probe fixture 751 may be transmitted to the electrode or the power supply pad. The electric signal transmitted to the target substrate SUB may form an electric field on the target substrate SUB.

[0135] However, the present disclosure is not limited thereto, and the probe pad 758 may be a member forming an electric field by an electric signal transferred from the probe fixture 751. That is, when the probe pad 758 forms an electric field by receiving an electric signal, the probe pad 758 may not be connected to the target substrate SUB.

[0136] The shape of the probe pad 758 is not particularly limited, but in an embodiment, the probe pad 758 may have a shape whose extended length involves the entire target substrate SUB.

[0137] The probe fixture 751 may be connected to the probe pad 758 and may be connected to a separate voltage applying device. The probe fixture 751 may transfer an electrical signal transferred from the voltage applying device to the probe pad 758 to form an electric field on the target substrate SUB. The electrical signal transferred to the probe fixture 751 may be a voltage for forming an electric field, such as an alternating current (AC) voltage.

[0138] The probe unit 750 may include a plurality of probe fixtures 751, and the number of the probe fixtures 751 is not particularly limited. In the drawings, three probe fixtures 751 and three probe drivers 753 are shown, but the probe unit 750 includes more probe fixtures 751 and more probe drivers 753 to form an electric field with a higher density on the target substrate SUB.

[0139] The probe unit 750 according to the embodiment is not limited thereto. It has been shown in the drawings that the probe unit 750 is disposed on the probe support 730 (i.e., is disposed as a part of the probe device 700), but in some cases, the probe unit 750 may also be disposed as a separate device. As long as the probe device 700 can form an electric field on the target substrate SUB by including a device capable of forming an electric field, the structure or arrangement of the probe device 700 is not limited.

[0140] Fig.11 and Fig.12 is a schematic diagram illustrating the operation of the probe unit according to the embodiment.

[0141] As described above, the probe driver 753 of the probe unit 750 may operate according to the process steps of the inkjet printing apparatus 1000. Fig.11 and Fig.12 In the first state (in which an electric field is not formed in the probe device 700), the probe unit 750 may be disposed on the probe support 730 to be spaced apart from the target substrate SUB. The probe driver 753 of the probe unit 750 may be driven in a first direction DR1 (which is a horizontal direction) and a third direction DR3 (which is a vertical direction) to allow the probe pad 758 to be spaced apart from the target substrate SUB.

[0142] Next, in the second state (forming an electric field on the target substrate SUB), the probe driver 753 of the probe unit 750 may be driven to connect the probe pad 758 to the target substrate SUB. The probe driver 753 may be driven in the third direction DR3 (which is a vertical direction) and the first direction DR1 (which is a horizontal direction) so that the probe pad 758 may contact the target substrate SUB. The probe fixture 751 of the probe unit 750 may transfer an electrical signal to the probe pad 758, and may form an electric field IEL on the target substrate SUB.

[0143] Meanwhile, it has been shown in the drawings that one probe unit 750 is arranged on each of the two sides of the probe device 700, and the two probe units 750 are connected to the target substrate SUB at the same time. However, the present disclosure is not limited thereto, and a plurality of probe units 750 may also be driven individually. For example, when the target substrate SUB is prepared on the sub-stage 710 and the ink 90 is ejected onto the target substrate SUB, any first probe unit 750 may first form an electric field on the target substrate SUB, and the second probe unit 750 may not be connected to the target substrate SUB. Thereafter, the first probe unit 750 may be disconnected from the target substrate SUB, and the second probe unit 750 may be connected to the target substrate SUB to form an electric field. That is, a plurality of probe units 750 may be driven simultaneously to form an electric field, or a plurality of probe units 750 may be driven sequentially to form an electric field sequentially.

[0144] Fig.13 is a schematic diagram illustrating generation of an electric field on a target substrate by a probe device according to an embodiment.

[0145] refer to Fig.13As described above, the bipolar element 95 may include a first end and a second end having polarity, and when the bipolar element 95 is placed in a predetermined electric field IEL, the dielectrophoretic force may be transmitted to the bipolar element 95 so that the position or orientation direction of the bipolar element 95 may be changed. A plurality of bipolar elements 95 in the ink 90 ejected onto the target substrate SUB may be positioned on the target substrate SUB while their positions and orientation directions are changed by the electric field IEL generated by the probe device 700.

[0146] The probe device 700 may generate an electric field IEL on the target substrate SUB, and the ink 90 discharged from the nozzle 350 of the inkjet head 300 may pass through the electric field IEL and be ejected onto the target substrate SUB. The bipolar element 95 may receive the dielectrophoretic force by the electric field IEL until the ink 90 reaches the target substrate SUB, or even until after the ink 90 reaches the target substrate SUB. According to an embodiment, after the bipolar element 95 is discharged from the inkjet head 300, the orientation direction and position of the bipolar element 95 may be changed by the electric field IEL generated by the probe device 700.

[0147] The electric field IEL generated by the probe device 700 may be formed in a direction parallel to the upper surface of the target substrate SUB. The bipolar element 95 ejected onto the target substrate SUB may be oriented by the electric field IEL so that the long axis of the bipolar element 95 along the direction in which it extends points to a direction parallel to the upper surface of the target substrate SUB. In addition, the bipolar element 95 may be placed on the target substrate SUB in a state where its first end having polarity is oriented in a specific direction.

[0148] When a plurality of bipolar elements 95 are disposed on a target substrate SUB, the degree of alignment may be measured in consideration of the deviation of the orientation direction of the plurality of bipolar elements 95 or the deviation of the position of the plurality of bipolar elements 95 disposed on the target substrate SUB. For the bipolar elements 95 disposed on the target substrate SUB, the deviation of the orientation direction and the deviation of the placement position of other bipolar elements 95 relative to any one bipolar element 95 may be measured, and the degree of alignment of the bipolar elements 95 may be measured by these deviations. The "degree of alignment" of the bipolar elements 95 may represent the deviation of the orientation direction and the placement position of the bipolar elements 95 aligned on the target substrate SUB. For example, it may be understood that when the deviation of the orientation direction and the placement position of the bipolar elements 95 is large, the degree of alignment of the bipolar elements 95 is low, and when the deviation of the orientation direction and the placement position of the bipolar elements 95 is small, the degree of alignment of the bipolar elements 95 is high or improved.

[0149] Meanwhile, the time point at which the probe device 700 generates the electric field IEL on the target substrate SUB is not particularly limited. It has been shown in the accompanying drawings that the probe unit 750 generates the electric field IEL when the ink 90 is discharged from the nozzle 350 and reaches the target substrate SUB. Therefore, the bipolar elements 95 can receive the dielectrophoretic force through the electric field IEL until they are discharged from the nozzle 350 and reach the target substrate SUB. However, the present disclosure is not limited thereto, and in some cases, the probe unit 750 can also generate the electric field IEL after the ink 90 is placed on the target substrate SUB. That is, the probe device 700 can generate the electric field IEL when the ink 90 is ejected from the inkjet head 300 or after the ink 90 is ejected from the inkjet head 300.

[0150] Although not shown in the drawings, in some embodiments, an electric field generating member may be further provided on the sub-stage 710. The electric field generating member may form an electric field in an upward direction (i.e., a third direction DR3) or on a target substrate SUB as the probe unit 750, which will be described later. In an embodiment, the electric field generating member may be an antenna unit, a device including a plurality of electrodes, etc.

[0151] Meanwhile, although not shown in the drawings, the inkjet printing apparatus 1000 according to the embodiment may further include a heat treatment unit in which a process of volatilizing the ink 90 sprayed onto the target substrate SUB is performed. The heat treatment unit radiates the ink 90 sprayed onto the target substrate SUB with heat so that the solvent 91 of the ink 90 may be volatilized and removed, and the bipolar element 95 may be disposed on the target substrate SUB. The process of removing the solvent 91 by radiating the ink 90 with heat may be performed using a conventional heat treatment unit. A detailed description thereof will be omitted.

[0152] Hereinafter, a method of printing bipolar element 95 using inkjet printing apparatus 1000 according to an embodiment will be described in detail.

[0153] Fig.14 is a flow chart illustrating a method for printing a bipolar element according to an embodiment. Figures 15 to 22 is a view illustrating a method for printing a bipolar element using an inkjet printing apparatus according to an embodiment.

[0154] refer to Figure 1 and Figures 14 to 22, the method for aligning bipolar elements 95 according to the embodiment may include setting inkjet printing device 1000 (step S100), discharging bipolar elements 95 through nozzle 350 and measuring the number of bipolar elements 95 discharged from nozzle 350 (step S200), determining whether the number of bipolar elements 95 exceeds a reference set value (step S300), and controlling droplets of ink 90 discharged from nozzle 350 per unit process based on the determination result (step S400).

[0155] The method for printing the bipolar element 95 according to the embodiment can use the above reference Figure 1 The printing process may be performed by the inkjet printing apparatus 1000 described above, and the number of bipolar elements 95 per unit droplet of ink 90 discharged from the inkjet head 300 may be measured and the bipolar elements 95 may be discharged. In the present specification, "printing" of the bipolar elements 95 may mean discharging or ejecting the bipolar elements 95 to a predetermined object in the inkjet printing apparatus 1000. For example, printing the bipolar elements 95 may mean directly ejecting the bipolar elements 95 through the nozzles 350 of the inkjet head 300, or ejecting the bipolar elements 95 in a state where the bipolar elements 95 are dispersed in the ink 90. ​​The present disclosure is not limited thereto, and printing the bipolar elements 95 may mean ejecting the bipolar elements 95 or the ink 90 in which the bipolar elements 95 are dispersed to the target substrate SUB (see Figure 7 ) to place the bipolar element 95 or ink 90 on the target substrate SUB.

[0156] The method for printing bipolar element 95 using inkjet printing apparatus 1000 may include measuring the number of bipolar elements 95 flowing in inkjet head 300 and determining whether the number of bipolar elements 95 exceeds a reference set value. A change in the number of bipolar elements 95 discharged through nozzle 350 may be sensed based on the determination result, and the sensed change may be fed back to actuator 390. When the number of bipolar elements 95 discharged from nozzle 350 per unit process needs to be changed, actuator 390 may control the droplets of ink 90 discharged from nozzle 350 per unit process based on the feedback signal.

[0157] First, the inkjet printing apparatus 1000 is set (step S100). The step S100 of setting the inkjet printing apparatus 1000 is a step of adjusting the inkjet printing apparatus 1000 according to the target process. For precise adjustment, an inkjet printing test process may be performed on an inspection substrate, and the setting value of the inkjet printing apparatus 1000 may be adjusted according to the test result.

[0158] Specifically, first, an inspection substrate is prepared. The inspection substrate may have the same structure as the target substrate SUB, but a bare substrate such as a glass substrate may be used as the inspection substrate.

[0159] Next, a water-repellent treatment is performed on the upper surface of the inspection substrate. The water-repellent treatment can be performed by fluorine coating, plasma surface treatment, or the like.

[0160] Next, the ink 90 including the bipolar element 95 is ejected onto the upper surface of the inspection substrate using the inkjet printing device 1000, and the droplets for each inkjet head 300 are measured. The measurement of the droplets for each inkjet head 300 can be performed in a manner that the size of the droplets when the ink 90 is ejected and the size of the droplets applied to the inspection substrate are confirmed using a camera. When the measured droplets are different from the reference droplets, the voltage for each corresponding inkjet head 300 is adjusted so that the reference droplets can be discharged. This inspection method can be repeated several times until each inkjet head 300 discharges accurate droplets.

[0161] Here, according to an embodiment, the step of setting inkjet printing apparatus 1000 may include the step of measuring the number of bipolar elements 95 in a droplet (e.g., a reference droplet) ejected onto the inspection substrate. The number of bipolar elements 95 included in the reference droplet ejected onto the inspection substrate may mean a reference setting value of the number of bipolar elements 95 per unit droplet of ink 90 in inkjet printing apparatus 1000. Based on the reference setting value set in inkjet printing apparatus 1000, a change in the number of bipolar elements 95 may be sensed, and the number of droplets of ink 90 discharged from nozzle 350 or bipolar elements 95 discharged through nozzle 350 per unit process may be controlled.

[0162] Furthermore, in the step of setting inkjet printing apparatus 1000, when the setting of the reference setting value is completed, ink 90 in which a plurality of bipolar elements 95 are dispersed may be prepared in ink circulation unit 500, and may be supplied to inkjet head 300. Ink circulation unit 500 and inkjet head 300 may be maintained so that bipolar elements 95 in ink 90 have a uniform dispersion through the ink circulation system.

[0163] However, the present disclosure is not limited thereto, and the step S100 of setting of the inkjet printing apparatus described above may be omitted.

[0164] Then, if Fig.15 As shown in , when the setting of the inkjet printing device 1000 is completed, the target substrate SUB is prepared. In an embodiment, the first electrode 21 and the second electrode 22 may be provided on the target substrate SUB. In the drawings, it has been shown that a pair of electrodes are provided, but more pairs of electrodes may be formed on the target substrate SUB, and a plurality of inkjet heads 300 may eject ink 90 onto each pair of electrodes in the same manner.

[0165] Then, if Fig.16 and Fig.17As shown in , an ink 90 including a solvent 91 in which a bipolar element 95 is dispersed is ejected onto a target substrate SUB. The ink 90 may be discharged from an inkjet head 300 and may be ejected onto a first electrode 21 and a second electrode 22 disposed on a target substrate SUB. The ink 90 may be ejected onto a first electrode 21 and a second electrode 22 disposed on a target substrate SUB, and the bipolar element 95 dispersed in the ink 90 may be ejected onto the target substrate SUB in a state in which it extends in one direction. In some embodiments, the bipolar elements 95 dispersed in the ink 90 may be oriented so that they may point to a direction perpendicular to the upper surface of the target substrate SUB along one direction in which they extend. In addition, in some embodiments, the corresponding bipolar elements 95 may be ejected in a state in which they are aligned so that their first end having a first polarity or their second end having a second polarity have the same direction. However, the present disclosure is not limited thereto.

[0166] like Fig.17 As shown in FIG. 1 , ink 90 may be discharged to a first area AA1 defined on a target substrate SUB during a first printing process. Ink 90 may be disposed in the first area AA1 together with bipolar elements 95. Bipolar elements 95 corresponding to the amount of droplets of ink 90 discharged from the inkjet head 300 and the number of bipolar elements 95 per unit droplet in the ink 90 may be ejected into the first area AA1.

[0167] The inkjet printing apparatus 1000 according to the embodiment may discharge or eject the ink 90 through the nozzle 350 and include the sensing unit 400 to measure the number of bipolar elements 95 discharged from the nozzle 350. The sensing unit 400 may at least measure the number of bipolar elements 95 introduced into the inkjet head 300 to measure the number of bipolar elements 95 per unit droplet of the ink 90 discharged from the nozzle 350. However, the present disclosure is not limited thereto, and in some embodiments, in addition to the bipolar elements 95 introduced into the inkjet head 300, the sensing unit 400 may also measure the number of bipolar elements 95 flowing in the inner tube 330 and the number of bipolar elements 95 introduced into the nozzle 350 to measure the number of bipolar elements 95 flowing in the inkjet head 300. Information on the number of measured bipolar elements 95 may be collected by each sensing unit 400 and may be used to measure the number of bipolar elements 95 per unit droplet of the ink 90 discharged through the nozzle 350.

[0168] The sensing unit 400 may measure the amount of the bipolar element 95 discharged from the nozzle 350 and sense a change in the amount of the bipolar element 95. For example, Fig.18As shown in , when the number of bipolar elements 95 per unit droplet of ink 90 discharged through nozzle 350 decreases, sensing unit 400 may determine whether the number of bipolar elements 95 decreases to exceed a reference set value (step S300). Alternatively, when the number of bipolar elements 95 per unit droplet of ink 90 discharged through nozzle 350 increases, sensing unit 400 may determine whether the number of bipolar elements 95 increases to exceed a reference set value (step S300). As described above, sensing unit 400 may determine whether the number of bipolar elements 95 exceeds a reference set value, sense a change in the number of bipolar elements 95 based on the determination result, and feed the sensed change back to actuator 390. Actuator 390 may receive the feedback signal transmitted from sensing unit 400 and adjust the droplets of ink 90 discharged from nozzle 350 of inkjet head 300.

[0169] For example, Fig.19 and Fig. 20 As shown in , the actuator 390 may receive a change in the number of bipolar elements 95 provided from the sensing unit 400 and adjust the number of droplets or liquid drops of the ink 90 discharged from the nozzle 350 per unit process. When the number of bipolar elements 95 in the ink 90 decreases, the actuator 390 may increase the number of liquid drops of the ink 90 discharged from the nozzle 350 per unit process.

[0170] For example, during the second printing process, ink 90 may be discharged to a second area AA2 defined on a target substrate SUB. Ink 90 may be placed in the second area AA2 together with bipolar elements 95. In the case where the number of bipolar elements 95 in ink 90 is reduced, when the same droplets of ink 90 as in the first printing process are discharged from nozzle 350, the number of bipolar elements 95 ejected into the second area AA2 may be less than the number of bipolar elements 95 ejected into the first area AA1. Actuator 390 may allow more droplets of ink 90 to be discharged, so that even if the number of bipolar elements 95 in ink 90 changes, the number of bipolar elements 95 ejected into the first area AA1 and the second area AA2 may be consistent. In the first printing process and the second printing process, the droplets of ink 90 ejected may be different from each other, but the number of bipolar elements 95 ejected may be the same as each other. Therefore, the inkjet printing device 1000 according to the embodiment can keep the number of bipolar elements 95 ejected onto the target substrate SUB per unit process consistent, and can improve the reliability of the manufactured product.

[0171] Meanwhile, as described above, bipolar element 95 may have a shape in which it extends in one direction, and respective ends of bipolar element 95 in the extending direction may have different polarities. The method for printing bipolar element 95 according to an embodiment may further include arranging bipolar element 95 so that bipolar element 95 points in one direction along the direction in which it extends.

[0172] refer to Fig.21 When the ink 90 in which the bipolar elements 95 are dispersed is ejected onto the target substrate SUB, an electric field IEL is generated on the target substrate SUB. The bipolar elements 95 may be disposed on the target substrate SUB while being oriented in one direction by the electric field IEL. In some embodiments, the bipolar elements 95 may be disposed between the first electrode 21 and the second electrode 22 by receiving a dielectrophoretic force via the electric field IEL generated on the target substrate SUB.

[0173] Specifically, an electrical signal is applied to the first electrode 21 and the second electrode 22 using the probe unit 750. The probe unit 750 may be connected to a predetermined pad provided on the target substrate SUB, and an electrical signal may be applied to the first electrode 21 and the second electrode 22 connected to the pad. In an embodiment, the electrical signal may be an AC voltage or a direct current (DC) voltage. When an AC voltage is applied to the first electrode 21 and the second electrode 22, an electric field IEL is formed between the first electrode 21 and the second electrode 22, and the bipolar element 95 receives a dielectrophoretic force through the electric field IEL. The bipolar element 95 to which the dielectrophoretic force is transmitted may be disposed on the first electrode 21 and the second electrode 22, while changing its orientation direction and position.

[0174] As shown in the figure, the orientation direction of the bipolar elements 95 extending in one direction in the ink 90 may vary according to the direction of the electric field IEL. According to an embodiment, the bipolar elements 95 may be aligned so that they point in the direction in which the electric field IEL points along one direction in which they extend. When the electric field IEL generated on the target substrate SUB is generated in parallel with the upper surface of the target substrate SUB, the bipolar elements 95 may be aligned so that they are parallel to the upper surface of the target substrate SUB along the direction in which they extend, and are disposed between the first electrode 21 and the second electrode 22. In some embodiments, the step of orienting the bipolar elements 95 may be a step of placing the bipolar elements 95 between the first electrode 21 and the second electrode 22, and at least one end of the bipolar elements 95 may be disposed on at least one of the first electrode 21 and the second electrode 22. However, the present disclosure is not limited thereto, and the bipolar elements 95 may be disposed directly on the target substrate SUB between the first electrode 21 and the second electrode 22.

[0175] Then, if Fig. 22As shown in FIG. 1 , a solvent 91 of the ink 90 sprayed onto the target substrate SUB is removed. The step of removing the solvent 91 is performed by a heat treatment device that can irradiate the target substrate SUB with heat or infrared rays. Since the solvent 91 is removed from the ink 90 sprayed onto the target substrate SUB, the flow of the bipolar element 95 can be prevented, and the bipolar element 95 can be placed on the electrodes 21 and 22.

[0176] Through the above-described method, the inkjet printing device 1000 according to the embodiment can print the bipolar element 95 on the target substrate SUB. The method for printing the bipolar element 95 according to the embodiment can maintain the use of Figure 1 The number of bipolar elements 95 discharged per unit process by inkjet printing apparatus 1000 is consistent. In addition, the method for printing bipolar elements 95 may further include positioning bipolar elements 95 so that bipolar elements 95 are oriented in one direction. Inkjet printing apparatus 1000 can manufacture a device including bipolar elements 95 oriented in one direction, and the device can include a consistent number of bipolar elements 95 per unit area, thereby improving the reliability of the product.

[0177] Hereinafter, various embodiments of the inkjet printing apparatus 1000 will be described.

[0178] As described above, inkjet printing apparatus 1000 includes sensing unit 400 disposed in inkjet head 300. Sensing unit 400 may measure the number of bipolar elements 95 per unit droplet of ink 90 discharged from nozzle 350 by the number of bipolar elements 95 per unit volume of ink 90 flowing in inkjet head 300. According to an embodiment, sensing unit 400 of inkjet printing apparatus 1000 may be disposed at another position within inkjet head 300, and the number of bipolar elements 95 may be accurately measured.

[0179] Fig.23 and Fig.24 is a cross-sectional view of an inkjet head according to another embodiment.

[0180] refer to Fig.23 , the sensing unit 400 may be disposed between the inlet 331 of the inner tube 330 of the inkjet head 300_1 and the nozzle 350. The sensing unit 400 may be disposed in the inner tube 330 in which the ink 90 flows, and may measure the amount of the bipolar element 95 before the ink 90 supplied to the inlet 331 of the inner tube 330 is introduced into the nozzle 350 through the filter F. Fig.23 The implementation method and Figure 5 The embodiment of the present invention is different in the arrangement of the sensing unit 400. Hereinafter, overlapping descriptions will be omitted, and contents different from those described above will be mainly described.

[0181] The sensing unit 400 may be disposed in the inner tube 330 in which the ink 90 flows before being introduced into the nozzle 350. The sensing unit 400 may be disposed closer to the nozzle 350 than the inlet 351 of the nozzle 350, and may at least measure the number of bipolar elements 95 in the ink 90 introduced into the inlet 351 of the nozzle 350. Furthermore, in some embodiments, in addition to the sensing unit 400 disposed close to the nozzle 350, the inkjet head 300_1 may further include a sensing unit 400 as shown in FIG. Figure 5 The sensing unit 400 is disposed at the inlet 331 of the inner tube 330 as in the embodiment of FIG.

[0182] In the inkjet printing apparatus 1000 according to the embodiment, the sensing unit 400 may be disposed closer to the nozzle 350 from which the ink 90 is discharged, and may more accurately measure a change in the amount of the bipolar elements 95 discharged from the inkjet head 300_1 .

[0183] Similarly, in some embodiments, the sensing unit 400 of the inkjet printing apparatus 1000 may be disposed at the nozzle 350 from which the ink 90 is discharged.

[0184] refer to Fig.24 , the sensing unit 400 of the inkjet printing device 1000 may also be disposed in the discharge portion 370 of the inkjet head 300_2. The sensing unit 400 may be disposed in the discharge portion 370 and disposed to correspond to each nozzle 350. The first sensing portion 410 and the second sensing portion 420 of the sensing unit 400 may be disposed to be spaced apart from each other, with the nozzle 350 interposed therebetween. The first sensing portion 410 may measure the number of bipolar elements 95 in the ink 90 introduced into the nozzle 350.

[0185] In some embodiments, the sensing unit 400 may be arranged in a form in which it is inserted into the discharge portion 370 to correspond to each nozzle 350 of the inkjet head 300_2, and the sensing unit 400 may be arranged in the first direction DR1 along the nozzles 350 arranged in the first direction DR1. In addition, a plurality of sensing units 400 may also be arranged in the second direction DR2 along the nozzles 350 arranged in the second direction DR2. The sensing unit 400 may be arranged to be spaced apart from other adjacent sensing units 400, and may be arranged to correspond to each nozzle 350.

[0186] According to an embodiment, the sensing unit 400 may be disposed above the actuator 390 disposed in the discharge portion 370. The sensing unit 400 may be disposed between the actuator 390 and the inner tube 330 to be adjacent to the inlet 351 of the nozzle 350, and may measure the number of bipolar elements 95 before the ink 90 passes through the actuator 390 and is discharged.

[0187] The bipolar element 95 has a shape in which it extends in one direction, and thus may gather at the inlet 351 of the nozzle 350, so that the number of bipolar elements 95 introduced into the nozzle 350 may be reduced. In this case, the number of bipolar elements 95 introduced into the inner tube 330 does not change, but the number of bipolar elements 95 discharged through the nozzle 350 may be reduced. When the sensing unit 400 is provided only at the inlet 331 of the inner tube 330, the reduction in the number of bipolar elements 95 at the inlet 351 of the nozzle 350 may not be sensed. In order to prevent such a problem, the sensing unit 400 may be provided in the discharge portion 370 of the inkjet head 300_2, and the number of bipolar elements 95 in the ink 90 immediately before being discharged from the nozzle 350 may be measured. Preferably, the sensing unit 400 may be provided at the inlet 331 of the inner tube 330 and the discharge portion 370 in which the nozzle 350 is provided, respectively, and the change in the number of bipolar elements 95 may be measured more accurately.

[0188] Meanwhile, the method for the sensing unit 400 to measure the number of the bipolar elements 95 is not limited to Figure 6 As described above, bipolar element 95 may have a small size and include parts having different polarities. Sensing unit 400 may measure the number of bipolar elements 95 by a method other than a method for directly photographing an image, taking into account the characteristics of bipolar element 95.

[0189] Fig.25 is a cross-sectional view illustrating that a sensing unit detects the number of bipolar elements according to another embodiment.

[0190] refer to Fig.25 , in the sensing unit 400_3, the first sensing part 410_3 may emit light of a specific wavelength band, and the second sensing part 420_3 may sense the light emitted from the first sensing part 410_3 to measure the number of bipolar elements 95 in the ink 90. ​​In an embodiment, the first sensing part 410_3 may be a light emitting part, and the second sensing part 420_3 may be a light receiving part. Fig.25 The implementation method and Figure 6The embodiment of the present invention is different in the method for the sensing unit 400_3 to measure the number of bipolar elements 95. Hereinafter, overlapping descriptions will be omitted, and contents different from those described above will be mainly described.

[0191] The first sensing portion 410_3 and the second sensing portion 420_3 of the sensing unit 400_3 may be disposed to be spaced apart from each other, and the inner tube 330 or the nozzle 350 through which the ink 90 flows is interposed between the first sensing portion 410_3 and the second sensing portion 420_3. The first sensing portion 410_3 and the second sensing portion 420_3 may be disposed to contact the outer wall of the inner tube 330 or the nozzle 350, but the present disclosure is not limited thereto, and the first sensing portion 410_3 and the second sensing portion 420_3 may also be spaced apart from the outer wall.

[0192] The first sensing portion 410_3 may emit light of a specific wavelength band, and the light emitted from the first sensing portion 410_3 may be incident on the second sensing portion 420_3. The type of the first sensing portion 410_3 is not particularly limited. In some embodiments, the first sensing portion 410_3 may be an ultraviolet laser irradiation device or lamp capable of emitting ultraviolet (UV) light, or may be a light irradiation device or lamp capable of emitting visible light or white light. However, the embodiment is not limited thereto, and the first sensing portion 410_3 is a device capable of irradiating the ink 90 with light, and may be modified differently as long as it can be adopted in the technical field. The first sensing portion 410_3 may irradiate the ink 90 with light, and the light may pass through the ink 90 and be incident on the second sensing portion 420_3.

[0193] When ink 90 is introduced into inkjet head 300, light emitted from first sensing portion 410_3 may be incident on bipolar element 95. The light may be partially scattered due to interference of bipolar element 95, and second sensing portion 420_3 may receive the light emitted from first sensing portion 410_3 and the scattered light to measure the number of bipolar elements 95 per unit volume or unit droplet of ink 90 flowing through inner tube 330.

[0194] The first sensing part 410_3 of the sensing unit 400_3 may radiate light L toward the second sensing part 420_3 (see Fig.25 ). The light L may at least partially irradiate the bipolar element 95 while passing through the ink 90 and incident on the second sensing portion 420_3. The bipolar element 95 may have a small size, and when the light L is irradiated to the bipolar element 95 dispersed in the ink 90, some of the light L may be scattered ( Fig.25In addition to the light L emitted from the first sensing portion 410_3, the light L' scattered by the bipolar element 95 may be incident on the second sensing portion 420_3. The light L' scattered by the bipolar element 95 may have a specific waveform according to the Brownian motion of the bipolar element 95. The second sensing portion 420_3 may measure the size of the bipolar element 95 by analyzing the waveform of the light L' scattered by the bipolar element 95, and may measure the number of bipolar elements 95 per unit volume or unit droplet of the ink 90 by the measured size. The sensing unit 400_3 may measure the number or dispersion degree of the bipolar elements 95 in the discharged ink 90 by the measured number of bipolar elements 95 and the droplets of the ink 90 discharged from the nozzle 350.

[0195] Meanwhile, according to an embodiment, the base portion 310 of the inkjet head 300 may have an outer wall made of a transparent material so that light emitted from the first sensing portion 410_3 of the sensing unit 400_3 may be irradiated to the bipolar element 95 in the ink 90. ​​Alternatively, the inner tube 330 or the nozzle 350 of the inkjet head 300 may have an outer wall made of a transparent material. The first sensing portion 410_3 and the second sensing portion 420_3 may be positioned to contact at least the outer wall of the inner tube 330 or the nozzle 350, and since the outer wall is made of a transparent material, the light emitted from the first sensing portion 410_3 may pass through the ink 90 and be incident on the second sensing portion 420_3.

[0196] Meanwhile, bipolar element 95 may include portions having different polarities, and bipolar element 95 itself may have a dipole moment directed in one direction. Bipolar element 95 may form an electric field (E-field) due to the dipole moment, and as shown in Formula 1 below, a magnetic field may be generated by a change in the electric field while a plurality of bipolar elements 95 flow along inner tube 330 in a state where they are dispersed in ink 90.

[0197] [Formula 1]

[0198]

[0199] In formula 1, “B” is the strength of the magnetic field, “μ 0 ” is the magnetic permeability, “J” is the current density, and “ε 0 ” is the dielectric constant, “E” is the strength of the electric field, and “t” is time.

[0200] Referring to Formula 1, the intensity of the magnetic field may have a value according to a change in the intensity of the electric field per unit time. When the bipolar element 95 moves, a change in the intensity of the electric field corresponding to the number of bipolar elements 95 per unit time may occur within a predetermined section. When the number of bipolar elements 95 introduced into the ink 90 in the inkjet head 300 changes, the change in the intensity of the electric field per unit time within the predetermined section may change, and therefore, the intensity of the magnetic field may change. According to an embodiment, the sensing unit 400 may measure the magnetic field by the movement of the bipolar element 95 to calculate the number of bipolar elements 95 per unit droplet of the ink 90.

[0201] Fig.26 is a cross-sectional view illustrating that a sensing unit detects the number of bipolar elements according to another embodiment.

[0202] refer to Fig.26 , when bipolar element 95 is supplied to inlet 331 of inner tube 330, a magnetic field B due to the movement of bipolar element 95 may be generated at inlet 331 of inner tube 330. According to an embodiment, sensing unit 400_4 may measure the intensity of magnetic field B due to the movement of bipolar element 95. First sensing part 410_4 may measure the intensity of magnetic field B generated in a predetermined section within inner tube 330, and second sensing part 420_4 may calculate the number of bipolar elements 95 based on the intensity of magnetic field B measured by first sensing part 410_4, and generate a feedback signal according to the calculated number of bipolar elements 95. However, the present disclosure is not limited thereto.

[0203] The sensing unit 400_4 is disposed at the inlet 331 of the inner tube 330 to which the ink 90 is supplied, and measures the intensity of the magnetic field B formed in a predetermined section of the inlet 331. The intensity of the magnetic field B may vary according to the change in the intensity of the electric field (i.e., the number and movement of the bipolar elements 95). When the number of bipolar elements 95 in the ink 90 supplied to the inkjet head 300 varies, the change in the intensity of the electric field caused by the bipolar elements 95 may vary, and the intensity of the magnetic field B formed in the predetermined section may vary. The first sensing portion 410_4 of the sensing unit 400_4 may sense such a change in the intensity of the magnetic field B, and the second sensing portion 420_4 of the sensing unit 400_4 may measure the change in the number of bipolar elements 95 flowing in the predetermined section. Therefore, the sensing unit 400_4 may transmit a feedback signal to the actuator 390, and the actuator 390 may control the droplets of the ink 90 discharged per unit process.

[0204] Meanwhile, the intensity of the magnetic field B formed by the bipolar element 95 in the predetermined section may vary due to the movement of the bipolar element 95, and may vary according to the flow speed of the ink 90. ​​According to an embodiment, in order to more effectively measure the change in the intensity of the magnetic field B, the inkjet head 300 may partially include a portion in which the flow speed of the ink 90 varies. The sensing unit 400 may be provided to correspond to the portion in which the flow speed of the ink 90 varies, and the change in the intensity of the magnetic field B caused by the bipolar element 95 may be measured more accurately.

[0205] Fig. 27 and Fig.28 is a cross-sectional view showing part of an inkjet head according to another embodiment.

[0206] First, refer to Fig. 27 , in the inkjet head 300_5 according to the embodiment, the inner tube 330 or the inlet 331 of the inner tube 330 may have a smaller diameter DH at the portion where the sensing unit 400 is provided than at other portions. When the ink 90 is supplied to the inlet 331 of the inner tube 330 or flows along the inner tube 330 and then passes through the section having a narrow diameter, the flow speed of the ink 90 may increase. When the flow speed of the ink 90 including the bipolar element 95 increases, the change in the intensity of the electric field per unit time caused by the bipolar element 95 within the predetermined section may increase, and the intensity of the magnetic field B measured by the sensing unit 400 may increase. When the intensity of the magnetic field B caused by the bipolar element 95 increases, the change in the intensity of the magnetic field B according to the change in the number of the bipolar elements 95 may also be easily sensed.

[0207] According to an embodiment, in the inkjet head 300_5, the inner tube 330 in which the ink 90 flows may include a portion whose diameter is partially narrowed, and the sensing unit 400 may be provided to correspond to the portion with the reduced diameter. Even if the intensity of the magnetic field B generated by the bipolar element 95 is weak, the flow speed of the ink 90 flowing in the region with a narrow diameter increases, so that the intensity of the magnetic field B can be increased, and the sensing unit 400 can accurately measure the change in the intensity of the magnetic field B.

[0208] Similarly, refer to Fig.28 , the inkjet head 300_6 may further include a sub-actuator PZT that changes the diameter of the inner tube 330. The inkjet head 300_6 according to the embodiment may further include a sub-actuator PZT that is disposed at the inner tube 330 or the inlet 331 of the inner tube 330 and reduces the diameter of the inner tube 330. The sub-actuator PZT may apply hydraulic pressure to the inner tube 330 in which the ink 90 flows, and the diameter of the inner tube 330 may be reduced. The flow speed of the ink 90 may increase as the diameter of the inner tube 330 decreases.

[0209] The sensing unit 400 may be disposed adjacent to the sub-actuator PZT and in a section where the flow velocity of the ink 90 increases. When the flow velocity of the ink 90 increases instantaneously by the sub-actuator PZT, the moving velocity of the bipolar element 95 also increases, and the intensity of the magnetic field B generated in the predetermined section increases.

[0210] Fig.29 is a cross-sectional view illustrating that a sensing unit detects the number of bipolar elements according to another embodiment.

[0211] In some embodiments, the strength of the dipole moment of bipolar element 95 may be varied by light L irradiated to bipolar element 95. When the strength of the dipole moment of bipolar element 95 varies, the strength of the electric field caused by bipolar element 95 may vary, which means that the strength of the magnetic field B generated by bipolar element 95 within a predetermined section may increase.

[0212] refer to Fig.29 , the sensing unit 400_7 according to the embodiment may further include a light emitting portion 430_7 capable of irradiating the ink 90 with the light L. The light emitting portion 430_7 may be disposed in the base portion 310 together with the first sensing portion 410_7, and may irradiate the ink 90 and the bipolar element 95 flowing in the inner tube 330 or the nozzle 350 with the light L of a specific wavelength band. In some embodiments, in the sensing unit 400_7, the first sensing portion 410_7 and the second sensing portion 420_7 may be disposed to be inserted into the base portion 310, and the light emitting portion 430_7 may be disposed on the outer surface of the base portion 310. As described above, in some embodiments, the base portion 310 of the inkjet head 300_7 may be made of a transparent material, and the light L emitted from the light emitting portion 430_7 may reach the ink 90 flowing through the inner tube 330.

[0213] The dipole moment of the bipolar element 95 may increase in response to the light L irradiated from the light emitting portion 430_7, and the intensity of the electric field caused by the plurality of bipolar elements 95 may increase. Therefore, the intensity of the magnetic field B generated by the bipolar element 95 within the predetermined section may also increase, and the sensing unit 400_7 may effectively sense the change in the intensity of the magnetic field B.

[0214] However, the method for measuring the number of bipolar elements 95 is not limited thereto. Bipolar elements 95 have a dipole moment, and therefore, when a plurality of bipolar elements 95 move, capacitance or current may be formed within a predetermined section. In this case, sensing unit 400_7 may measure the capacitance or current of bipolar elements 95, and the number of bipolar elements 95 may be measured based on the measured capacitance or current.

[0215] The inkjet printing apparatus 1000 according to the embodiment may include a sensing unit 400, 400_3, 400_4, or 400_7 disposed in the inkjet head 300, 300_1, 300_2, 300_5, 300_6, or 300_7 and capable of measuring the number of bipolar elements 95. The sensing unit 400, 400_3, 400_4, or 400_7 may directly or indirectly measure the number of bipolar elements 95 in the ink 90 discharged from the inkjet head 300, 300_1, 300_2, 300_5, 300_6, or 300_7, and sense a change in the number of bipolar elements 95. The change in the number of bipolar elements 95 can be transmitted to the actuator 390 of the inkjet head 300, 300_1, 300_2, 300_5, 300_6 or 300_7, and the actuator 390 can adjust the droplets of the discharged ink 90. ​​The inkjet printing device 1000 can keep the number of bipolar elements 95 discharged per unit process consistent by adjusting the droplets of the discharged ink 90. ​​Therefore, the inkjet printing device 1000 can improve the reliability of the product manufactured to include the bipolar element 95.

[0216] Meanwhile, the bipolar element 95 described above may be a light emitting element including a plurality of semiconductor layers, and according to an embodiment, a display device including the light emitting element may be manufactured using the inkjet printing apparatus 1000 .

[0217] Fig.30 is a schematic diagram of a light emitting element according to an embodiment.

[0218] The light emitting element 30 may be a light emitting diode. Specifically, the light emitting element 30 may be an inorganic light emitting diode having a size in the micrometer or nanometer range and made of an inorganic material. The inorganic light emitting diode may be aligned between two electrodes, wherein when an electric field is formed in a specific direction between two electrodes facing each other, polarity is formed in the two electrodes. The light emitting element 30 may be aligned between the two electrodes by an electric field formed on the two electrodes.

[0219] refer to Fig.30 , the light emitting element 30 according to the embodiment may have a shape in which it extends in one direction. The light emitting element 30 may have a shape such as a rod shape, a wire shape, or a tube shape. In an embodiment, the light emitting element 30 may have a cylindrical shape or a rod shape. However, the light emitting element 30 is not limited to having the shape described above, and may have various shapes. For example, the light emitting element 30 may have a polygonal prism shape such as a cube shape, a rectangular parallelepiped shape, or a hexagonal prism shape, or have a shape in which it extends in one direction but its outer surface is partially inclined.

[0220] The light emitting element 30 may include a semiconductor layer doped with impurities of any conductive type (e.g., p-type or n-type). The semiconductor layer may receive an electrical signal applied from an external power source to emit light of a specific wavelength band. A plurality of semiconductors included in the light emitting element 30 may have a structure in which they are sequentially arranged or stacked in one direction.

[0221] The light emitting element 30 may include a first semiconductor layer 31 , a second semiconductor layer 32 , an active layer 36 , an electrode layer 37 , and an insulating film 38 . Fig.30 The insulating film 38 is partially removed to expose the plurality of semiconductor layers 31, 32, and 36 in order to visually illustrate the respective components of the light emitting element 30. However, as described later, the insulating film 38 may be provided to surround the outer surfaces of the plurality of semiconductor layers 31, 32, and 36.

[0222] Specifically, the first semiconductor layer 31 may be an n-type semiconductor. As an example, when the light emitting element 30 emits light in a blue wavelength band, the first semiconductor layer 31 may include a semiconductor having a chemical formula of Al x Ga y In 1-x-y N (0≤x≤1, 0≤y≤1 and 0≤x+y≤1). For example, the semiconductor material may be one or more of AlGaInN, GaN, AlGaN, InGaN, AlN and InN doped with an n-type dopant. The first semiconductor layer 31 may be doped with an n-type dopant, and as an example, the n-type dopant may be Si, Ge, Sn, Se, etc. In an embodiment, the first semiconductor layer 31 may be made of n-GaN doped with n-type Si. The length of the first semiconductor layer 31 may be in the range of 1.5μm to 5μm, but is not limited thereto.

[0223] The second semiconductor layer 32 is disposed on the active layer 36 to be described later. The second semiconductor layer 32 may be a p-type semiconductor, and as an example, when the light emitting element 30 emits light of a blue or green wavelength band, the second semiconductor layer 32 may include a semiconductor having a chemical formula of Al x Ga y In 1-x-y N (0≤x≤1, 0≤y≤1 and 0≤x+y≤1). For example, the semiconductor material may be one or more of AlGaInN, GaN, AlGaN, InGaN, AlN and InN doped with a p-type dopant. The second semiconductor layer 32 may be doped with a p-type dopant, and as an example, the p-type dopant may be Mg, Zn, Ca, Ba, etc. In an embodiment, the second semiconductor layer 32 may be made of p-GaN doped with p-type Mg. The length of the second semiconductor layer 32 may be in the range of 0.05 μm to 0.10 μm, but is not limited thereto.

[0224] Meanwhile, each of the first semiconductor layer 31 and the second semiconductor layer 32 is configured as one layer, but the present disclosure is not limited thereto. According to some embodiments, each of the first semiconductor layer 31 and the second semiconductor layer 32 may further include more layers, such as a cladding layer or a tensile strain barrier reduction (TSBR) layer, depending on the material of the active layer 36.

[0225] The active layer 36 is disposed between the first semiconductor layer 31 and the second semiconductor layer 32. The active layer 36 may include a material having a single quantum well or a multi-quantum well structure. When the active layer 36 includes a material having a multi-quantum well structure, the active layer 36 may have a structure in which a plurality of quantum layers and well layers are alternately stacked. The active layer 36 may emit light by combining electron-hole pairs according to an electrical signal applied through the first semiconductor layer 31 and the second semiconductor layer 32. As an example, when the active layer 36 emits light in a blue wavelength band, the active layer 36 may include a material such as AlGaN or AlGaInN. Specifically, when the active layer 36 has a multi-quantum well structure (i.e., a structure in which quantum layers and well layers are alternately stacked), 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. In an embodiment, the active layer 36 may include AlGaInN as a material for the quantum layer, and include AlInN as a material for the well layer to emit blue light having a central wavelength band of 450nm to 495nm.

[0226] However, the present disclosure is not limited thereto, and the active layer 36 may have a structure in which a semiconductor material having a large energy band gap and a semiconductor material having a small energy band gap are alternately stacked, and may include other III-group to V-group semiconductor materials according to the wavelength band of the emitted light. The light emitted by the active layer 36 is not limited to the light of the blue wavelength band, and in some cases, the active layer 36 may emit light of the red and green wavelength bands. The length of the active layer 36 may be in the range of 0.05 μm to 0.10 μm, but is not limited thereto.

[0227] Meanwhile, light emitted from active layer 36 may be emitted not only to the outer surface of light emitting element 30 in the length direction but also to both side surfaces of light emitting element 30. Directivity of light emitted from active layer 36 is not limited to one direction.

[0228] The electrode layer 37 may be an ohmic contact electrode. However, the present disclosure is not limited thereto, and the electrode layer 37 may also be a Schottky contact electrode. The light emitting element 30 may include at least one electrode layer 37. Fig.303 has shown that the light emitting element 30 includes one electrode layer 37, but the present disclosure is not limited thereto. In some cases, the light emitting element 30 may also include a greater number of electrode layers 37, or the electrode layer 37 may also be omitted. Even if the number of electrode layers 37 is changed or the light emitting element 30 includes another structure, the description of the light emitting element 30 provided later may also be applied in the same manner.

[0229] When the light emitting element 30 is electrically connected to the display device 10 according to the embodiment (see Fig.31 ), the electrode layer 37 can reduce the resistance between the light emitting element 30 and the electrode or the contact electrode. The electrode layer 37 may include a metal having conductivity. The electrode layer 37 may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). The electrode layer 37 may include a semiconductor material doped with an n-type or p-type dopant. The electrode layer 37 may include the same material or include different materials. The length of the electrode layer 37 may be in the range of 0.05 μm to 0.10 μm, but is not limited thereto.

[0230] The insulating film 38 is provided to surround the outer surfaces of the plurality of semiconductor layers and the electrode layer described above. In an embodiment, the insulating film 38 may be provided to surround at least the outer surface of the active layer 36, and may extend in one direction along which the light emitting element 30 extends. The insulating film 38 may be used to protect these components. As an example, the insulating film 38 may be formed to surround the side surface portions of these components, but may be formed to expose both ends of the light emitting element 30 in the length direction.

[0231] It has been shown in the drawings that the insulating film 38 is formed to extend in the length direction of the light emitting element 30 to cover the side surfaces of the first semiconductor layer 31 to the electrode layer 37, but the present disclosure is not limited thereto. The insulating film 38 may cover only some of the semiconductor layers and the outer surface of the active layer 36 or only a portion of the outer surface of the electrode layer 37, so that the outer surface of each electrode layer 37 may be partially exposed. In addition, the insulating film 38 may also be formed so that in cross section, its upper surface is rounded in a region adjacent to at least one end of the light emitting element 30.

[0232] The thickness of the insulating film 38 may be in the range of 10 nm to 1.0 μm, but is not limited thereto. The thickness of the insulating film 38 may preferably be about 40 nm.

[0233] The insulating film 38 may include a material having insulating properties, such as silicon oxide (SiO x ), Silicon Nitride (SiN x ), silicon oxynitride (SiO x N y), aluminum nitride (AlN) and aluminum oxide (Al 2 O 3 ). Therefore, it is possible to prevent an electrical short circuit that may occur when the active layer 36 is in direct contact with an electrode through which an electrical signal is transmitted to the light emitting element 30. In addition, the insulating film 38 protects the light emitting element 30 and the outer surface of the active layer 36, and thus it is possible to prevent a decrease in light emitting efficiency.

[0234] In addition, in some embodiments, the outer surface of the insulating film 38 may be surface treated. When manufacturing the display device 10, the light emitting element 30 may be ejected and aligned onto the electrode in a state where it is dispersed in a predetermined ink. Here, in order to keep the light emitting element 30 in a state where the light emitting element 30 is dispersed and not aggregated with other adjacent light emitting elements 30 in the ink, a hydrophobic or hydrophilic treatment may be performed on the surface of the insulating film 38.

[0235] The length h of the light emitting element 30 may be in the range of 1 μm to 10 μm or 2 μm to 6 μm, and preferably in the range of 3 μm to 5 μm. In addition, the diameter of the light emitting element 30 may be in the range of 30 nm to 700 nm, and the aspect ratio of the light emitting element 30 may be 1.2 to 100. However, the present disclosure is not limited thereto, and the plurality of light emitting elements 30 included in the display device 10 may also have different diameters depending on the composition between the active layers 36. Preferably, the diameter of the light emitting element 30 may be about 500 nm.

[0236] According to an embodiment, the inkjet printing device 1000 can Fig.30 The light emitting elements 30 are dispersed in the ink 90 , and the ink 90 in which the light emitting elements 30 are dispersed is ejected or discharged onto the target substrate SUB to manufacture the display device 10 including the light emitting elements 30 .

[0237] Fig.31 is a schematic plan view of a display device according to an embodiment.

[0238] refer to Fig.31 , the display device 10 displays a moving image or a still image. The display device 10 may represent all electronic devices that provide a display screen. For example, the display device 10 may be included in a television, a laptop computer, a monitor, a billboard, an Internet of Things (IoT) device, a mobile phone, a smart phone, a tablet personal computer (PC), an electronic watch, a smart watch, a watch phone, a head-mounted display, a mobile communication terminal, an electronic notebook, an electronic book, a portable multimedia player (PMP), a navigation device, a game console, a digital camera, a camcorder, etc. that provide a display screen.

[0239] The shape of the display device 10 may be modified variously. For example, the display device 10 may have a shape such as a rectangular shape with a width greater than a length, a rectangular shape with a length greater than a width, a square shape, a rectangular shape with rounded corners (vertices), other polygonal shapes, or a circular shape. 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. Fig.31 , a display device 10 and a display area DPA having a rectangular shape in which the width is greater than the length are shown.

[0240] The display device 10 may include a display area DPA and a non-display area NDA. The display area DPA is an area in which an image can be displayed, and the non-display area NDA is an area in which an image is not displayed. The display area DPA may also be referred to as an active area, and the non-display area NDA may also be referred to as a non-active area.

[0241] The display area DPA may substantially occupy the center of the display device 10. The display area DPA may include a plurality of pixels PX. The plurality of pixels PX may be arranged in a matrix form. In a plan view, the shape of each pixel PX may be a rectangular shape or a square shape, but is not limited thereto, and may also be a diamond shape in which each side thereof is inclined relative to one direction. Each of the pixels PX may include one or more light emitting elements 30 that emit light of a specific wavelength band to present a specific color.

[0242] Fig.32 is a schematic plan view of one pixel of a display device according to an embodiment.

[0243] refer to Fig.32 , each of the plurality of pixels PX may include a first sub-pixel PX1, a second sub-pixel PX2, and a third sub-pixel PX3. The first sub-pixel PX1 may emit light of a first color, the second sub-pixel PX2 may emit light of a second color, and the third sub-pixel 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, the present disclosure is not limited thereto, and corresponding sub-pixels PXn (e.g., PX1, PX2, and PX3) may also emit light of the same color. In addition, in Fig.32 2 has shown that the pixel PX includes three sub-pixels PXn, but the present disclosure is not limited thereto, and the pixel PX may include a greater number of sub-pixels PXn.

[0244] Each of the sub-pixels PXn of the display device 10 may include an area defined as an emission area EMA. The first sub-pixel PX1 may include a first emission area EMA1, the second sub-pixel PX2 may include a second emission area EMA2, and the third sub-pixel PX3 may include a third emission area EMA3. The emission area EMA may be defined as an area in which the light emitting element 30 included in the display device 10 is disposed to emit light of a specific wavelength band.

[0245] Each of the subpixels PXn of the display device 10 may include a non-emission region defined as a region other than the emission region EMA. The non-emission region may be a region where the light emitting element 30 is not disposed and light emitted from the light emitting element 30 does not reach, thereby not emitting light.

[0246] Each sub-pixel PXn of the display device 10 may include a plurality of electrodes 21 and 22, a light emitting element 30, a plurality of contact electrodes 26, and a plurality of internal banks 41 and 42 (see Fig.33 ), an outer bank 43, and at least one insulating layer 51, 52, 53 and 55 (see Fig.33 ).

[0247] The plurality of electrodes 21 and 22 may be electrically connected to the light emitting element 30 and may receive a predetermined voltage applied thereto so that the light emitting element 30 emits light of a specific wavelength band. In addition, at least a portion of each of the electrodes 21 and 22 may be used to form an electric field in the sub-pixel PXn so as to align the light emitting element 30.

[0248] The plurality of electrodes 21 and 22 may include a first electrode 21 and a second electrode 22. In an embodiment, the first electrode 21 may be a pixel electrode separated for each sub-pixel PXn, and the second electrode 22 may be a common electrode commonly connected along each sub-pixel PXn. One of the first electrode 21 and the second electrode 22 may be an anode electrode of the light emitting element 30, and the other of the first electrode 21 and the second electrode 22 may be a cathode electrode of the light emitting element 30. However, the first electrode 21 and the second electrode 22 are not limited thereto, and vice versa.

[0249] The first electrode 21 and the second electrode 22 may respectively include electrode rod portions 21S and 22S arranged to extend in the fourth direction DR4, and may respectively include at least one electrode branch portion 21B and 22B extending in a fifth direction DR5 and branching from the electrode rod portions 21S and 22S, wherein the fifth direction DR5 is a direction crossing the fourth direction DR4.

[0250] The first electrode 21 may include a first electrode rod portion 21S disposed to extend in the fourth direction DR4 , and at least one first electrode branch portion 21B branched from the first electrode rod portion 21S and extending in the fifth direction DR5 .

[0251] The first electrode rod portion 21S of any one subpixel PXn may have two ends spaced apart from each other and terminated between the corresponding subpixels PXn, but may be disposed on substantially the same straight line as the first electrode rod portion 21S of the subpixel PXn adjacent in the same row (e.g., adjacent in the fourth direction DR4). The first electrode rod portion 21S disposed in the corresponding subpixel PXn may have two ends spaced apart from each other to apply different electrical signals to the corresponding first electrode branch portions 21B, and the first electrode branch portions 21B may be driven individually.

[0252] The first electrode branch portions 21B may be branched from at least a portion of the first electrode rod portion 21S and may be disposed to extend in the fifth direction DR5, but may terminate in a state where they are spaced apart from the second electrode rod portion 22S disposed to face the first electrode rod portion 21S.

[0253] The second electrode 22 may include a second electrode rod portion 22S extending in the fourth direction DR4 and spaced apart from the first electrode rod portion 21S in the fifth direction DR5 and facing the first electrode rod portion 21S, and a second electrode branch portion 22B branched from the second electrode rod portion 22S and extending in the fifth direction DR5. The other end of the second electrode rod portion 22S may be connected to the second electrode rod portion 22S of another sub-pixel PXn adjacent in the fourth direction DR4. That is, unlike the first electrode rod portion 21S, the second electrode rod portion 22S may be disposed to extend in the fourth direction DR4 to cross over each sub-pixel PXn. The second electrode rod portion 22S crossing over each sub-pixel PXn may be connected to a portion extending in one direction in an outer portion of the display area DPA in which each pixel PX or sub-pixel PXn is disposed or in the non-display area NDA.

[0254] The second electrode branch portion 22B may be spaced apart from and face the first electrode branch portion 21B, and may terminate in a state where it is spaced apart from the first electrode rod portion 21S. The second electrode branch portion 22B may be connected to the second electrode rod portion 22S, and one end of the second electrode branch portion 22B in the extension direction may be disposed in the subpixel PXn in a state where it is spaced apart from the first electrode rod portion 21S.

[0255] The first electrode 21 and the second electrode 22 may be electrically connected to the circuit element layer of the display device 10 through contact holes (e.g., first electrode contact hole CNTD and second electrode contact hole CNTS), respectively. It has been shown in the drawings that the first electrode contact hole CNTD is formed for each of the first electrode rod portions 21S of each sub-pixel PXn, and only one second electrode contact hole CNTS is formed for one second electrode rod portion 22S across each sub-pixel PXn. However, the present disclosure is not limited thereto, and in some cases, the second electrode contact hole CNTS may also be formed for each sub-pixel PXn.

[0256] The outer bank 43 may be disposed at the boundary between the respective sub-pixels PXn, and the plurality of inner banks 41 and 42 may be adjacent to the central portion of each sub-pixel PXn and disposed under the respective electrodes 21 and 22. The plurality of inner banks 41 and 42 may not be disposed at the boundary between the respective sub-pixels PXn. Fig.32 shown in, but reference Fig.33 , the first inner bank 41 and the second inner bank 42 may be disposed under the first electrode branch portion 21B and the second electrode branch portion 22B, respectively.

[0257] The outer bank 43 may be disposed at the boundary between each sub-pixel PXn. The respective ends of the plurality of first electrode rod portions 21S may be spaced apart from each other and terminated based on the outer bank 43. The outer bank 43 may extend in the fifth direction DR5 and be disposed at the boundary between the sub-pixels PXn arranged in the fourth direction DR4. However, the present disclosure is not limited thereto, and the outer bank 43 may also extend in the fourth direction DR4 and may also be disposed at the boundary between the sub-pixels PXn arranged in the fifth direction DR5. The outer bank 43 may include the same material as the inner banks 41 and 42 and may be formed simultaneously with the inner banks 41 and 42 in one process.

[0258] The light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22. One end of the light emitting element 30 may be electrically connected to the first electrode 21, and the other end of the light emitting element 30 may be electrically connected to the second electrode 22. The light emitting element 30 may be electrically connected to the first electrode 21 and the second electrode 22, respectively, through contact electrodes 26 to be described later.

[0259] A plurality of light emitting elements 30 may be arranged to be spaced apart from each other and may be aligned substantially parallel to each other. The intervals between the light emitting elements 30 spaced apart from each other are not particularly limited. In some cases, a plurality of light emitting elements 30 may be arranged adjacent to each other and grouped, and a plurality of other light emitting elements 30 may be grouped in a state where they are spaced apart from a plurality of light emitting elements 30 by a predetermined interval, or a plurality of light emitting elements 30 may have an uneven density, but may be oriented and aligned in one direction. In addition, in an embodiment, the light emitting element 30 may have a shape in which it extends in one direction, and the direction in which the corresponding electrode (e.g., the first electrode branch portion 21B and the second electrode branch portion 22B) extends and the direction in which the light emitting element 30 extends may be substantially perpendicular to each other. However, the present disclosure is not limited thereto, and the light emitting element 30 is not perpendicular to the direction in which the first electrode branch portion 21B and the second electrode branch portion 22B extend, and may be arranged to be inclined relative to the direction in which the first electrode branch portion 21B and the second electrode branch portion 22B extend.

[0260] The light emitting element 30 according to the embodiment may include an active layer 36 including different materials to emit light of different wavelength bands to the outside. In the display device 10, the light emitting element 30 of the first sub-pixel PX1 may emit a first light whose central wavelength band is a first wavelength, the light emitting element 30 of the second sub-pixel PX2 may emit a second light whose central wavelength band is a second wavelength, and the light emitting element 30 of the third sub-pixel PX3 may emit a third light whose central wavelength band is a third wavelength. Therefore, the first light may be emitted from the first sub-pixel PX1, the second light may be emitted from the second sub-pixel PX2, and the third light may be emitted from the third sub-pixel PX3. In some embodiments, the first light may be blue light having a central wavelength band in the range of 450nm to 495nm, the second light may be green light having a central wavelength band in the range of 495nm to 570nm, and the third light may be red light having a central wavelength band in the range of 620nm to 750nm. However, the present disclosure is not limited thereto.

[0261] Despite Fig.32 , but the display device 10 may include a second insulating layer 52 covering at least a portion of the first electrode 21 and the second electrode 22 (see Fig.33 ).

[0262] The second insulating layer 52 may be disposed in each sub-pixel PXn of the display device 10. The second insulating layer 52 may be disposed to substantially completely cover each sub-pixel PXn, and may also be disposed to extend to other adjacent sub-pixels PXn. The second insulating layer 52 may be disposed to cover at least a portion of the first electrode 21 and the second electrode 22. The second insulating layer 52 may be disposed to expose portions of the first electrode 21 and the second electrode 22, specifically, to expose partial regions of the first electrode branch portion 21B and the second electrode branch portion 22B.

[0263] The plurality of contact electrodes 26 may have a shape in which at least a portion of the area thereof extends in one direction. Each of the plurality of contact electrodes 26 may contact the light emitting element 30 and the electrodes 21 and 22, and the light emitting element 30 may receive an electrical signal from the first electrode 21 and the second electrode 22 through the contact electrode 26.

[0264] The contact electrode 26 may include a first contact electrode 26a and a second contact electrode 26b. The first contact electrode 26a and the second contact electrode 26b may be disposed on the first electrode branch portion 21B and the second electrode branch portion 22B, respectively.

[0265] The first contact electrode 26a may be disposed on the first electrode 21 or the first electrode branch portion 21B and extend in the fifth direction DR5. The first contact electrode 26a may contact one end of the light emitting element 30. In addition, the first contact electrode 26a may contact the first electrode 21 exposed without disposing the second insulating layer 52 thereon. Therefore, the light emitting element 30 may be electrically connected to the first electrode 21 through the first contact electrode 26a.

[0266] The second contact electrode 26b may be disposed on the second electrode 22 or the second electrode branch portion 22B and extend in the fifth direction DR5. The second contact electrode 26b may be spaced apart from the first contact electrode 26a in the fourth direction DR4. The second contact electrode 26b may contact the other end of the light emitting element 30. In addition, the second contact electrode 26b may contact the second electrode 22 exposed without the second insulating layer 52 disposed thereon. Therefore, the light emitting element 30 may be electrically connected to the second electrode 22 through the second contact electrode 26b. It has been shown in the drawings that two first contact electrodes 26a and one second contact electrode 26b are disposed in one sub-pixel PXn, but the present disclosure is not limited thereto. The number of the first contact electrode 26a and the second contact electrode 26b may vary according to the number of the first electrode 21 and the second electrode 22 or the first electrode branch portion 21B and the second electrode branch portion 22B disposed in each sub-pixel PXn.

[0267] In some embodiments, the widths of the first contact electrode 26a and the second contact electrode 26b measured in one direction may be respectively greater than the widths of the first electrode 21 and the second electrode 22 or the first electrode branch portion 21B and the second electrode branch portion 22B measured in one direction. However, the present disclosure is not limited thereto, and in some cases, the first contact electrode 26a and the second contact electrode 26b may also be provided to cover only one side portion of the first electrode branch portion 21B and the second electrode branch portion 22B, respectively.

[0268] Meanwhile, in addition to the second insulating layer 52, the display device 10 may include a circuit element layer positioned below each of the electrodes 21 and 22, and a third insulating layer 53 (see FIG. 5 ) further disposed to cover each of the electrodes 21 and 22 and at least a portion of the light emitting element 30. Fig.33 ) and the passivation layer 55 (see Fig.33 ). In the following, reference will be made to Fig.33 The structure of the display device 10 is described in detail.

[0269] Fig.33 It is along Fig.32 Cross-sectional views taken along line Xa-Xa', line Xb-Xb' and line Xc-Xc'.

[0270] Fig.33 Only the cross section of the first sub-pixel PX1 is shown, which may be similarly applied to other pixels PX or sub-pixels PXn. Fig.33 A cross section across one end and the other end of the light emitting element 30 provided in the first sub-pixel PX1 is shown.

[0271] At the same time, despite Fig.33 Although not shown in the figure, the display device 10 may further include a circuit element layer positioned below each of the electrodes 21 and 22. The circuit element layer may include a plurality of semiconductor layers and a plurality of conductive patterns, and may include at least one transistor and a power line.

[0272] refer to Fig.32 and Fig.33 , the display device 10 may include a first insulating layer 51, and electrodes 21 and 22, a light emitting element 30, etc. disposed on the first insulating layer 51. A circuit element layer (not shown) may be further disposed under the first insulating layer 51. The first insulating layer 51 may include an organic insulating material to perform a surface planarization function.

[0273] A plurality of inner banks 41 and 42 , an outer bank 43 , a plurality of electrodes 21 and 22 , and a light emitting element 30 may be disposed on the first insulating layer 51 .

[0274] When manufacturing the display device 10, when using the above-described Figure 1When the inkjet printing device 1000 ejects ink, the outer bank 43 may be used to prevent the ink in which the light emitting elements 30 are dispersed from crossing the boundary between the sub-pixels PXn. The outer bank 43 may separate the ink in which different light emitting elements 30 are dispersed from each other for each of the different sub-pixels PXn so that the inks are not mixed with each other. However, the present disclosure is not limited thereto.

[0275] The plurality of inner banks 41 and 42 may include a first inner bank 41 and a second inner bank 42 disposed adjacent to a central portion of each sub-pixel PXn.

[0276] The first inner bank 41 and the second inner bank 42 are disposed to be spaced apart from each other and face each other. The first electrode 21 may be disposed on the first inner bank 41, and the second electrode 22 may be disposed on the second inner bank 42. Fig.32 and Fig.33 It can be understood that the first electrode branch portion 21B is disposed on the first inner bank 41 , and the second electrode branch portion 22B is disposed on the second inner bank 42 .

[0277] The first inner bank 41 and the second inner bank 42 may be provided to extend in the fifth direction DR5 in each sub-pixel PXn. However, the present disclosure is not limited thereto, and the first inner bank 41 and the second inner bank 42 may be provided for each sub-pixel PXn to form a pattern in the entire display device 10. The plurality of inner banks 41 and 42 and the outer bank 43 may include polyimide (PI), but are not limited thereto.

[0278] The first inner bank 41 and the second inner bank 42 may have a structure in which at least a portion thereof protrudes relative to the first insulating layer 51. The first inner bank 41 and the second inner bank 42 may protrude upward relative to the plane on which the light emitting element 30 is disposed, and at least a portion of the protruding portion may have an inclination. Since the inner banks 41 and 42 protrude relative to the first insulating layer 51 and have an inclined side surface, light emitted from the light emitting element 30 may be reflected on the inclined side surfaces of the inner banks 41 and 42. As described later, when the electrodes 21 and 22 disposed on the inner banks 41 and 42 include a material having a high reflectivity, light emitted from the light emitting element 30 may be reflected by the electrodes 21 and 22 and travel in an upward direction of the first insulating layer 51.

[0279] The outer bank 43 is disposed at the boundary between the respective sub-pixels PXn to form a mesh pattern, but the inner banks 41 and 42 are disposed within each sub-pixel PXn and have a shape in which they extend in one direction.

[0280] A plurality of electrodes 21 and 22 may be disposed on the first insulating layer 51 and the inner banks 41 and 42. As described above, the electrodes 21 and 22 include electrode rod portions 21S and 22S, respectively, and electrode branch portions 21B and 22B, respectively.

[0281] Partial regions of the first electrode 21 and the second electrode 22 may be disposed on the first insulating layer 51, and other partial regions of the first electrode 21 and the second electrode 22 may be disposed on the first inner bank 41 and the second inner bank 42, respectively. As described above, the first electrode rod portion 21S of the first electrode 21 and the second electrode rod portion 22S of the second electrode 22 may extend in the fourth direction DR4, and the first inner bank 41 and the second inner bank 42 may extend in the fifth direction DR5, and may also be disposed in the sub-pixels PXn adjacent to each other in the fifth direction DR5.

[0282] A first electrode contact hole CNTD that passes through the first insulating layer 51 and exposes a portion of the circuit element layer may be formed in the first electrode rod portion 21S of the first electrode 21. The first electrode 21 may be electrically connected to the transistor of the circuit element layer through the first electrode contact hole CNTD. A predetermined electrical signal may be transmitted from the transistor to the first electrode 21.

[0283] The second electrode rod portion 22S of the second electrode 22 may extend in one direction and may also be disposed in a non-emitting region in which the light emitting element 30 is not disposed. A second electrode contact hole CNTS that passes through the first insulating layer 51 and exposes a portion of the circuit element layer may be formed in the second electrode rod portion 22S. The second electrode 22 may be electrically connected to the power electrode through the second electrode contact hole CNTS. A predetermined electrical signal may be transmitted from the power electrode to the second electrode 22.

[0284] Partial regions of the first electrode 21 and the second electrode 22 (e.g., the first electrode branch portion 21B and the second electrode branch portion 22B) may be respectively disposed on the first inner bank 41 and the second inner bank 42. A plurality of light emitting elements 30 may be disposed in a region between the first electrode 21 and the second electrode 22, that is, in a space where the first electrode branch portion 21B and the second electrode branch portion 22B are spaced apart from each other and face each other.

[0285] Each of the electrodes 21 and 22 may include a transparent conductive material. As an example, each of the electrodes 21 and 22 may include a material such as indium tin oxide (ITO), indium zinc oxide (IZO), or indium tin zinc oxide (ITZO), but is not limited thereto. In some embodiments, each of the electrodes 21 and 22 may include a conductive material having a high reflectivity. For example, each of the electrodes 21 and 22 may include a metal such as silver (Ag), copper (Cu), or aluminum (Al) as a material having a high reflectivity. In this case, light incident on each of the electrodes 21 and 22 may be reflected to be emitted in an upward direction of each sub-pixel PXn.

[0286] In addition, the electrodes 21 and 22 may have a structure in which one or more layers made of a transparent conductive material and one or more layers made of a metal having high reflectivity are stacked, or may be formed as one layer including a transparent conductive material and a metal having high reflectivity. In an embodiment, each of the electrodes 21 and 22 may have a stacked structure of ITO / silver (Ag) / ITO / IZO, or be made of an alloy including aluminum (Al), nickel (Ni), lanthanum (La), etc. However, the present disclosure is not limited thereto.

[0287] The second insulating layer 52 is disposed on the first insulating layer 51, the first electrode 21, and the second electrode 22. The second insulating layer 52 is disposed to partially cover the first electrode 21 and the second electrode 22. The second insulating layer 52 may be disposed to cover most of the upper surfaces of the first electrode 21 and the second electrode 22, but may expose portions of the first electrode 21 and the second electrode 22. The second insulating layer 52 may be disposed so that portions of the upper surfaces of the first electrode 21 and the second electrode 22 (e.g., portions of the upper surfaces of the first electrode branch portions 21B disposed on the first inner bank 41 and portions of the upper surfaces of the second electrode branch portions 22B disposed on the second inner bank 42) are exposed. That is, the second insulating layer 52 may be substantially completely formed on the first insulating layer 51, but may include openings that partially expose the first electrode 21 and the second electrode 22.

[0288] In an embodiment, the second insulating layer 52 may have a step formed so that a portion of its upper surface is recessed between the first electrode 21 and the second electrode 22. In some embodiments, the second insulating layer 52 may include an inorganic insulating material, and a portion of the upper surface of the second insulating layer 52 disposed to cover the first electrode 21 and the second electrode 22 may be recessed due to a step of a member disposed below the second insulating layer 52. The light emitting element 30 may be disposed on the second insulating layer 52 between the first electrode 21 and the second electrode 22, and an empty space may be formed between the recessed upper surfaces of the light emitting element 30 and the second insulating layer 52. The light emitting element 30 may be disposed to be partially spaced apart from the upper surface of the second insulating layer 52, and a material constituting the third insulating layer 53 to be described later may be filled in the space. However, the present disclosure is not limited thereto. The second insulating layer 52 may form a flat upper surface on which the light emitting element 30 is disposed.

[0289] The second insulating layer 52 can insulate the first electrode 21 and the second electrode 22 from each other while protecting the first electrode 21 and the second electrode 22. In addition, the second insulating layer 52 can prevent the light emitting element 30 disposed on the second insulating layer 52 from directly contacting other components and being damaged by other components. However, the shape and structure of the second insulating layer 52 are not limited thereto.

[0290] The light emitting element 30 may be disposed between the corresponding electrodes 21 and 22 on the second insulating layer 52. As an example, at least one light emitting element 30 may be disposed between the corresponding electrode branch portions 21B and 22B on the second insulating layer 52. However, the present disclosure is not limited thereto, and although not shown in the drawings, at least some of the light emitting elements 30 disposed in each sub-pixel PXn may also be disposed in an area other than the area between the electrode branch portions 21B and 22B. The light emitting element 30 may be disposed on the corresponding ends of the first electrode branch portion 21B and the second electrode branch portion 22B facing each other, and may be electrically connected to the corresponding electrodes 21 and 22 through the contact electrode 26.

[0291] The light emitting element 30 may include a plurality of layers arranged in a direction parallel to the upper surface of the first insulating layer 51. The light emitting element 30 of the display device 10 according to the embodiment may have a shape in which it extends in one direction, and may have a structure in which a plurality of semiconductor layers are sequentially arranged in one direction. As described above, in the light emitting element 30, the first semiconductor layer 31, the active layer 36, the second semiconductor layer 32, and the electrode layer 37 may be sequentially arranged along one direction, and the insulating film 38 may surround the outer surface of the first semiconductor layer 31, the active layer 36, the second semiconductor layer 32, and the electrode layer 37. The light emitting element 30 provided in the display device 10 may be arranged so that the light emitting element 30 is parallel to the upper surface of the first insulating layer 51 in one direction in which it extends, and the plurality of semiconductor layers included in the light emitting element 30 may be sequentially arranged in a direction parallel to the upper surface of the first insulating layer 51. However, the present disclosure is not limited thereto. In some cases, when the light emitting element 30 has another structure, the plurality of layers may also be arranged in a direction perpendicular to the upper surface of the first insulating layer 51.

[0292] In addition, one end of the light emitting element 30 may be in contact with the first contact electrode 26a, and the other end of the light emitting element 30 may be in contact with the second contact electrode 26b. According to an embodiment, the end surface of the light emitting element 30 extending in one direction is exposed without the insulating film 38, and therefore, the light emitting element 30 may be in contact with the first contact electrode 26a and the second contact electrode 26b to be described later in the exposed area. However, the present disclosure is not limited thereto. In some cases, at least a portion of the insulating film 38 of the light emitting element 30 is removed so that the end side surfaces of the light emitting element 30 can be partially exposed.

[0293] The third insulating layer 53 may be partially disposed on the light emitting element 30 disposed between the first electrode 21 and the second electrode 22. The third insulating layer 53 may be disposed to partially surround the outer surface of the light emitting element 30. The third insulating layer 53 may protect the light emitting element 30 and is used to fix the light emitting element 30 in the process of manufacturing the display device 10. In addition, in an embodiment, a portion of the material of the third insulating layer 53 may also be disposed between the lower surface of the light emitting element 30 and the second insulating layer 52. As described above, the third insulating layer 53 may also be formed to fill the space between the second insulating layer 52 and the light emitting element 30 formed during the process of manufacturing the display device 10. Therefore, the third insulating layer 53 may be formed to surround the outer surface of the light emitting element 30. However, the present disclosure is not limited thereto.

[0294] The third insulating layer 53 may be provided to extend in the fifth direction DR5 between the first electrode branch portion 21B and the second electrode branch portion 22B in a plan view. As an example, the third insulating layer 53 may have an island shape or a linear shape in a plan view on the first insulating layer 51. According to an embodiment, the third insulating layer 53 may be provided on the light emitting element 30.

[0295] The first contact electrode 26a and the second contact electrode 26b are disposed on the electrodes 21 and 22, respectively, and on the third insulating layer 53. The first contact electrode 26a and the second contact electrode 26b may be disposed to be spaced apart from each other on the third insulating layer 53. The third insulating layer 53 may insulate the first contact electrode 26a and the second contact electrode 26b from each other so that the first contact electrode 26a and the second contact electrode 26b do not directly contact each other.

[0296] The first contact electrode 26a may contact the exposed partial area of ​​the first electrode 21 on the first inner bank 41, and the second contact electrode 26b may contact the exposed partial area of ​​the second electrode 22 on the second inner bank 42. The first contact electrode 26a and the second contact electrode 26b may transfer electrical signals transferred from the corresponding electrodes 21 and 22 to the light emitting element 30.

[0297] The contact electrode 26 may include a conductive material. For example, the contact electrode 26 may include ITO, IZO, ITZO, aluminum (Al), etc. However, the present disclosure is not limited thereto.

[0298] The passivation layer 55 may be disposed on the contact electrode 26 and the third insulating layer 53. The passivation layer 55 may serve to protect members disposed on the first insulating layer 51 from external environments.

[0299] Each of the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 described above may include an inorganic insulating material or an organic insulating material. In an embodiment, the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 may include an inorganic insulating material or an organic insulating material. x ), Silicon Nitride (SiN x ), silicon oxynitride (SiO x N y ), aluminum oxide (Al 2 O 3) or an inorganic insulating material of aluminum nitride (AlN). In addition, the second insulating layer 52, the third insulating layer 53 and the passivation layer 55 may include 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. as an organic insulating material. However, the present disclosure is not limited thereto.

[0300] Figure 34 to Figure 36 are cross-sectional views illustrating some processes of a method for manufacturing a display device according to an embodiment.

[0301] refer to Figure 34 to Figure 36 The display device 10 according to the embodiment can use the above reference Figure 1 The inkjet printing device 1000 may be manufactured by the inkjet printing device 1000 described above. The inkjet printing device 1000 may eject the ink 90 in which the light emitting element 30 is dispersed, and the light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22 of the display device 10.

[0302] First, if Fig.34 As shown in FIG. 1 , a first insulating layer 51, a first inner bank 41 and a second inner bank 42 disposed on the first insulating layer 51 to be spaced apart from each other, a first electrode 21 and a second electrode 22 disposed on the first inner bank 41 and the second inner bank 42, respectively, and a second insulating material layer 52' ​​covering the first electrode 21 and the second electrode 22 are prepared. The second insulating material layer 52' ​​may be partially patterned in a subsequent process to form the second insulating layer 52 of the display device 10. The above-described components may be formed by patterning metal, inorganic material, organic material, etc. through a conventional mask process.

[0303] Next, the ink 90 in which the light emitting elements 30 are dispersed is ejected onto the first electrode 21 and the second electrode 22. The light emitting element 30 may be a bipolar element, and the ink 90 in which the light emitting elements 30 are dispersed may be ejected using the inkjet printing apparatus 1000 and the method for printing a bipolar element described above. As shown in the figure, the inkjet printing apparatus 1000 according to the embodiment may discharge the ink 90 while uniformly maintaining the number of light emitting elements 30 in the ink 90. ​​The description thereof is the same as that described above, and thus the detailed description will be omitted.

[0304] Then, if Fig.35As shown in , an electric signal is applied to the first electrode 21 and the second electrode 22 to generate an electric field IEL in the ink 90 in which the light emitting element 30 is dispersed. The light emitting element 30 can receive the dielectrophoretic force transmitted by the electric field IEL and can be arranged on the first electrode 21 and the second electrode 22 while changing the orientation direction and position of the light emitting element 30.

[0305] Then, if Fig.36 As shown in , the solvent 91 of the ink 90 is removed. The light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22 through the above-described process. Thereafter, although not shown in the drawings, the second insulating material layer 52' ​​may be patterned to form a second insulating layer 52, and a third insulating layer 53, a first contact electrode 26a, a second contact electrode 26b, and a passivation layer 55 may be formed to manufacture the display device 10.

[0306] Meanwhile, the shape and material of the light emitting element 30 are not limited to Fig.30 In some embodiments, the light emitting element 30 can include a greater number of layers or have other shapes.

[0307] Fig.37 and Fig.38 is a schematic diagram of a light emitting element according to another embodiment.

[0308] refer to Fig.37 According to the embodiment, the light emitting element 30' may further include a third semiconductor layer 33' disposed between the first semiconductor layer 31' and the active layer 36', and a fourth semiconductor layer 34' and a fifth semiconductor layer 35' disposed between the active layer 36' and the second semiconductor layer 32'. Fig.30 The light emitting element 30 of the embodiment of the present invention is different in that a plurality of semiconductor layers 33', 34' and 35' and electrode layers 37a' and 37b' are further provided, and the active layer 36' includes other elements. The arrangement and structure of the insulating film 38' are similar to those of the embodiment of the present invention. Fig.30 The insulating film 38 in is basically the same.

[0309] As mentioned above, in Fig.30 In the light emitting element 30 of FIG. 1 , the active layer 36 may include nitrogen (N) to emit blue light or green light. Fig.37 In the light emitting element 30', the active layer 36' and the other semiconductor layers may be semiconductors including at least phosphorus (P), respectively. That is, the light emitting element 30' according to the embodiment may emit red light having a central wavelength band in the range of 620nm to 750nm. However, it will be understood that the central wavelength band of red light is not limited to the range described above, and includes all wavelength ranges that can be considered red in the technical field.

[0310] Specifically, the first semiconductor layer 31' may be an n-type semiconductor layer, and when the light emitting element 30' emits red light, the first semiconductor layer 31' may include a semiconductor layer having a chemical formula In x Al y Ga 1-x-y P (0≤x≤1, 0≤y≤1 and 0≤x+y≤1). For example, the first semiconductor layer 31' may be made of one or more of InAlGaP, GaP, AlGaP, InGaP, AlP and InP doped with an n-type dopant. The first semiconductor layer 31' may be doped with an n-type dopant, and as an example, the n-type dopant may be Si, Ge, Sn, Se, etc. In an embodiment, the first semiconductor layer 31' may be made of n-AlGaInP doped with n-type Si. The length of the first semiconductor layer 31' may be in the range of 1.5μm to 5μm, but is not limited thereto.

[0311] The second semiconductor layer 32' may be a p-type semiconductor layer, and when the light emitting element 30' emits red light, the second semiconductor layer 32' may include a layer having a chemical formula In x Al y Ga 1-x-y The second semiconductor layer 32' may be made of a semiconductor material of P (0≤x≤1, 0≤y≤1 and 0≤x+y≤1). For example, the second semiconductor layer 32' may be made of one or more of InAlGaP, GaP, AlGaNP, InGaP, AlP and InP doped with a p-type dopant. The second semiconductor layer 32' may be doped with a p-type dopant, and as an example, the p-type dopant may be Mg, Zn, Ca, Ba, etc. In an embodiment, the second semiconductor layer 32' may be made of p-GaN doped with p-type Mg. The length of the second semiconductor layer 32' may be in the range of 0.08μm to 0.25μm, but is not limited thereto.

[0312] The active layer 36' may be disposed between the first semiconductor layer 31' and the second semiconductor layer 32'. Fig.30 Similar to the active layer 36, Fig.37The active layer 36' may also include a material having a single quantum well or a multiple quantum well structure to emit light in a specific wavelength band. As an example, when the active layer 36' emits light in a red wavelength band, the active layer 36' may include a material such as AlGaP or AlInGaP. Specifically, when the active layer 36' has a multiple quantum well structure (i.e., a structure in which quantum layers and well layers are alternately stacked), the quantum layer may include a material such as AlGaP or AlInGaP, and the well layer may include a material such as GaP or AlInP. In an embodiment, the active layer 36' may include AlGaInP as a material for the quantum layer and AlInP as a material for the well layer to emit red light with a central wavelength band of 620nm to 750nm.

[0313] The light emitting element 30' may include a cladding layer disposed adjacent to the active layer 36'. As shown in the figure, the third semiconductor layer 33' and the fourth semiconductor layer 34' disposed below and above the active layer 36', respectively, between the first semiconductor layer 31' and the second semiconductor layer 32' may be cladding layers.

[0314] The third semiconductor layer 33' may be disposed between the first semiconductor layer 31' and the active layer 36'. The third semiconductor layer 33' may be an n-type semiconductor similar to the first semiconductor layer 31', and as an example, the third semiconductor layer 33' may include a semiconductor having a chemical formula In x Al y Ga 1-x-y P (0≤x≤1, 0≤y≤1, and 0≤x+y≤1). In an embodiment, the first semiconductor layer 31 ′ may be made of n-AlGaInP, and the third semiconductor layer 33 ′ may be made of n-AlInP. However, the present disclosure is not limited thereto.

[0315] The fourth semiconductor layer 34' may be disposed between the active layer 36' and the second semiconductor layer 32'. The fourth semiconductor layer 34' may be a p-type semiconductor similar to the second semiconductor layer 32', and as an example, the fourth semiconductor layer 34' may include a semiconductor having a chemical formula In x Al y Ga 1-x-y A semiconductor material of P (0≤x≤1, 0≤y≤1, and 0≤x+y≤1). In an embodiment, the second semiconductor layer 32 ′ may be made of p-GaP, and the fourth semiconductor layer 34 ′ may be made of p-AlInP.

[0316] The fifth semiconductor layer 35' may be disposed between the fourth semiconductor layer 34' and the second semiconductor layer 32'. Similar to the second semiconductor layer 32' and the fourth semiconductor layer 34', the fifth semiconductor layer 35' may be a semiconductor doped with a p-type dopant. In some embodiments, the fifth semiconductor layer 35' may be used to reduce the difference in lattice constant between the fourth semiconductor layer 34' and the second semiconductor layer 32'. That is, the fifth semiconductor layer 35' may be a tensile strain barrier reduction (TSBR) layer. As an example, the fifth semiconductor layer 35' may include p-GaInP, p-AlInP, p-AlGaInP, etc., but is not limited thereto. In addition, the lengths of the third semiconductor layer 33', the fourth semiconductor layer 34' and the fifth semiconductor layer 35' may be in the range of 0.08 μm to 0.25 μm, but are not limited thereto.

[0317] The first electrode layer 37a' and the second electrode layer 37b' may be disposed on the first semiconductor layer 31' and the second semiconductor layer 32', respectively. The first electrode layer 37a' may be disposed on the lower surface of the first semiconductor layer 31', and the second electrode layer 37b' may be disposed on the upper surface of the second semiconductor layer 32'. However, the present disclosure is not limited thereto, and at least one of the first electrode layer 37a' and the second electrode layer 37b' may be omitted. For example, in the light emitting element 30', the first electrode layer 37a' may not be disposed on the lower surface of the first semiconductor layer 31', and only one second electrode layer 37b' may be disposed on the upper surface of the second semiconductor layer 32'.

[0318] Next, refer to Fig.38 , the light emitting element 30 ″ may have a shape in which it extends in one direction, but may have a shape in which a side surface thereof is partially inclined. That is, the light emitting element 30 ″ according to the embodiment may have a partially tapered shape.

[0319] The light emitting element 30" may be formed such that a plurality of layers are not stacked in one direction, and the corresponding layers surround the outer surface of any other layer. The light emitting element 30" may be formed such that a plurality of semiconductor layers surround at least a portion of the outer surface of any other layer. The light emitting element 30" may include a semiconductor core and an insulating film 38", wherein at least a partial region of the semiconductor core extends in one direction, and the insulating film 38" is formed to surround the semiconductor core. The semiconductor core may include a first semiconductor layer 31", an active layer 36", a second semiconductor layer 32", and an electrode layer 37". Except that the shapes of the corresponding layers are partially different, the light emitting element 30" is different from Fig.30 Hereinafter, description of the same contents will be omitted, and contents different from those described above will be described.

[0320] According to an embodiment, the first semiconductor layer 31″ may be formed to extend in one direction and to have two ends inclined toward a central portion. The first semiconductor layer 31″ may have a main body portion in a rod shape or a cylindrical shape, and end portions respectively formed at an upper portion and a lower portion of the main body portion and formed to have an inclined side surface. The upper end of the main body portion may have a steeper inclination than the lower end of the main body portion.

[0321] The active layer 36" is arranged to surround the outer surface of the main portion of the first semiconductor layer 31". The active layer 36" may have an annular shape extending in one direction. The active layer 36" may not be formed on the upper and lower ends of the first semiconductor layer 31". The active layer 36" may be formed only on the non-inclined side surface of the first semiconductor layer 31". However, the present disclosure is not limited to this. Therefore, the light emitted from the active layer 36" can be emitted not only to the two ends of the light emitting element 30" in the length direction, but also to the two side surfaces of the light emitting element 30" relative to the length direction. Fig.38 The active layer 36" of the light emitting element 30" may have a Fig.30 The area of ​​the light emitting element 30 is larger than the area of ​​the Fig.30 The amount of light of the light emitting element 30 is a greater amount of light.

[0322] The second semiconductor layer 32" is disposed to surround the outer surface of the active layer 36" and the upper end of the first semiconductor layer 31". The second semiconductor layer 32" may include a main body portion extending in one direction and having a ring shape, and an upper end formed to have an inclined side surface. That is, the second semiconductor layer 32" may be in direct contact with the parallel side surfaces of the active layer 36" and the inclined upper end of the first semiconductor layer 31". However, the second semiconductor layer 32" is not formed at the lower end of the first semiconductor layer 31".

[0323] The electrode layer 37 ″ is disposed to surround the outer surface of the second semiconductor layer 32 ″. That is, the shape of the electrode layer 37 ″ may be substantially the same as that of the second semiconductor layer 32 ″. That is, the electrode layer 37 ″ may completely contact the outer surface of the second semiconductor layer 32 ″.

[0324] The insulating film 38" may be disposed to surround the outer surfaces of the electrode layer 37" and the first semiconductor layer 31". The insulating film 38" may be in direct contact with the lower end of the first semiconductor layer 31", and the exposed lower ends of the active layer 36", and the second semiconductor layer 32", and the electrode layer 37".

[0325] The display device 10 having a uniform number of light-emitting elements 30, 30' or 30" disposed in each pixel PX and sub-pixel PXn can be manufactured using the inkjet printing device 1000 according to the embodiment. In the display device 10, the deviation in the number of light-emitting elements 30, 30' or 30" in each pixel PX and sub-pixel PXn can be minimized, and the light-emitting reliability for each pixel PX can be improved.

[0326] At the end of the detailed description, those skilled in the art will appreciate that many changes and modifications may be made to the preferred embodiment without departing from the principles of the invention in essence. Therefore, the preferred embodiments of the present invention disclosed are used only in an overview and descriptive sense, and not for a limiting purpose.

Claims

1. An inkjet printing device comprising: tower; an inkjet head positioned above the stage and including a plurality of nozzles through which ink including a bipolar element having regions doped to have different polarities is discharged; an actuator disposed in the inkjet head; as well as at least one sensing unit disposed in the inkjet head and measuring the amount of the bipolar element discharged through the nozzle, The actuator receives a signal related to the number of the bipolar elements measured by the sensing unit and adjusts a droplet of the ink discharged from the nozzle.

2. The inkjet printing device according to claim 1, wherein: The inkjet head includes a base portion, a discharge portion connected to the base portion and in which the plurality of nozzles are disposed, and an inner tube to which the ink is supplied, and The ink is supplied to and flows in the inner tube, and is discharged through the nozzle.

3. The inkjet printing device according to claim 2, wherein: The sensing unit includes a first sensing part and a second sensing part, wherein the first sensing part measures a magnetic field generated in the ink according to the movement of the bipolar element, and the second sensing part transmits the signal related to the number of the bipolar elements calculated by the magnetic field measured by the first sensing part to the actuator.

4. The inkjet printing device according to claim 3, wherein: The sensing unit is provided at an inlet of the inner tube to which the ink is supplied.

5. The inkjet printing device according to claim 4, wherein: The inlet of the inner tube has a smaller diameter at a portion where the sensing unit is provided than at other portions.

6. The inkjet printing apparatus according to claim 4, further comprising a sub-actuator provided in the inkjet head and adjusting a diameter of the inner tube in which the ink flows, in, The sub-actuator increases a flow velocity of the ink flowing in the inner tube.

7. The inkjet printing device according to claim 3, wherein: The sensing unit is disposed between an inlet of the inner tube and the nozzle.

8. The inkjet printing device according to claim 3, wherein: The sensing unit is disposed in the discharge portion.

9. The inkjet printing device according to claim 3, wherein: The sensing unit also includes a light emitting part that irradiates the bipolar element with light.

10. The inkjet printing device according to claim 9, wherein: The base portion of the inkjet head is made of a transparent material.

11. A method for printing a bipolar component, comprising: preparing ink in which a plurality of bipolar elements are dispersed, and supplying the ink to an inkjet head; measuring the amount of the bipolar elements in the discharged ink while discharging the ink from the inkjet head; as well as When the number of the bipolar elements in the ink exceeds a reference set value, droplets of the ink discharged from the inkjet head are adjusted.

12. The method for printing a bipolar component according to claim 11, wherein: The measuring of the number of the bipolar elements is performed by at least one sensing unit provided in the inkjet head, and The sensing unit measures a magnetic field generated in the ink according to the movement of the bipolar element.

13. The method for printing a bipolar component according to claim 12, wherein: Adjusting the droplets of discharged ink comprises: sensing, by the sensing unit, a change in the number of the bipolar elements; and The droplets of the ink discharged per unit process are adjusted according to the change in the number of the bipolar elements.

14. The method for printing a bipolar component according to claim 13, wherein: ejecting the ink discharged from the inkjet head onto a target substrate, and The method for printing a bipolar element further includes positioning the bipolar element on the target substrate.

15. The method for printing a bipolar component according to claim 14, wherein: defining a plurality of regions on the target substrate, and Based on the change in the number of the bipolar elements, the droplets of the ink are adjusted so that the number of the bipolar elements ejected into the plurality of regions is uniform.

16. The method for printing a bipolar component according to claim 12, wherein: Measuring the number of the bipolar elements in the discharged ink while discharging the ink is performed using an inkjet printing device, The inkjet printing device comprises: tower; the inkjet head positioned above the stage and including a plurality of nozzles through which the ink including the bipolar element having regions doped to have different polarities is discharged; an actuator that is provided in the inkjet head and regulates the droplets of the ink discharged from the nozzle; and the at least one sensing unit measuring the amount of the bipolar element discharged through the nozzle, and wherein the actuator adjusts the droplet of the ink discharged from the nozzle according to a change in the number of the bipolar elements measured by the sensing unit.

17. A method for manufacturing a display device, comprising: preparing a target substrate including a plurality of regions divided from each other and having a first electrode and a second electrode formed in the plurality of regions; ejecting ink into the plurality of regions while controlling droplets of the ink according to the number of light emitting elements dispersed in the ink; as well as placing the light emitting element on the first electrode and the second electrode, Wherein, ejecting the ink comprises: measuring the number of the light emitting elements in the ejected ink; and When the number of the light emitting elements in the ejected ink exceeds a reference set value, the number of the light emitting elements is controlled by adjusting the droplets of the ink ejected into the plurality of areas.

18. The method for manufacturing a display device according to claim 17, wherein: The light emitting element includes a first semiconductor layer doped to have a first polarity, a second semiconductor layer doped to have a second polarity different from the first polarity, and an active layer disposed between the first semiconductor layer and the second semiconductor layer.

19. The method for manufacturing a display device according to claim 18, wherein: Measuring the number of the light emitting elements in the ejected ink includes measuring a magnetic field generated in the ink according to movement of the light emitting elements.

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