Printhead unit and inkjet printer comprising a printhead unit

Abstract

This application relates to a printhead unit and an inkjet printer including the printhead unit. The inkjet printer includes a substrate on a table. The printhead unit is positioned above the table and discharges ink to the substrate. The printhead unit includes a manifold in which movement of the ink is directed in a first direction. A head block is below the manifold and includes a plurality of channels connected to the manifold and piezoelectric elements adjacent to the channels to discharge ink through the channels. A nozzle unit is below the head block and includes nozzles corresponding to the channels. A dispersion plate is between the manifold and the head block and disperses the ink in a second direction that intersects the first direction to supply the ink to the head block. A resistance plate is between the dispersion plate and the head block, formed substantially parallel to the second direction, and prevents the ink from flowing in the first direction.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0125226, filed on September 25, 2020, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] Aspects of some embodiments of the present application relate to a print head unit and an inkjet printer including the print head unit. BACKGROUND

[0004] As interest in information display and demand for use of portable information media increases, research and commercialization of display devices are being actively conducted.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not constitute prior art. SUMMARY

[0006] Aspects of some embodiments of the present application relate to a print head unit and an inkjet printer including the print head unit.

[0007] An inkjet printer according to some embodiments of the present application includes a substrate on a stage; a print head unit positioned above the stage and configured to discharge ink to the substrate; and an ink supply unit configured to supply ink to the print head unit, wherein the print head unit includes a manifold configured to guide movement of the ink therein in a first direction; a head block below the manifold and including a plurality of passages connected to the manifold and piezoelectric elements adjacent to the passages to discharge the ink through the passages; a nozzle unit below the head block and including nozzles corresponding to the passages; a dispersion plate between the manifold and the head block and configured to disperse the ink in a second direction intersecting the first direction to supply the ink to the head block; and a resistance plate between the dispersion plate and the head block, formed substantially parallel to the second direction, and configured to prevent the ink from flowing in the first direction.

[0008] According to some embodiments, the ink can include a solid dispersed in a solvent, and the solid can be at least one selected from a light emitting element, a quantum dot, and a color filter material, each of which has a diameter or length in a range from a nanometer level to a micrometer level.

[0009] According to some embodiments, a first surface of the dispersion plate adjacent to the manifold can be inclined along the second direction, and the ink supplied to the dispersion plate can be supplied between the dispersion plate and the head block along the first surface.

[0010] According to some embodiments, a second surface of the dispersion plate adjacent to the head block can include a central portion and a peripheral portion positioned in a second direction with respect to the central portion, the central portion can be higher than the peripheral portion with respect to an upper surface of the head block, and the resistance plate can be at the central portion.

[0011] According to some embodiments, the resistance plate can be arranged at equal intervals along the first direction.

[0012] According to some embodiments, a length of the dispersion plate in the first direction can be greater than a length of the head block in the first direction, and the dispersion plate can cover the head block in the first direction.

[0013] According to some embodiments, some of the resistance plates can be adjacent to both sides of the dispersion plate in the first direction.

[0014] According to some embodiments, a distance between the resistance plates in an area adjacent to one side of the dispersion plate in the first direction can be different from a distance between the resistance plates in an area adjacent to a central portion of a planar area of the dispersion plate.

[0015] According to some embodiments, the resistance plate can be integrally formed with the dispersion plate.

[0016] According to some embodiments, the resistance plate can be formed by bending from a mother substrate parallel to a lower surface of the dispersion plate, and the mother substrate can be coupled to the dispersion plate.

[0017] According to some embodiments, the print head unit can further include a filter between the manifold and the dispersion plate.

[0018] A print head unit according to some embodiments of the present invention includes a manifold configured to guide movement of ink therein in a first direction, a head block below the manifold and including a plurality of channels connected to the manifold and piezoelectric elements adjacent to the channels to discharge the ink through the channels, a nozzle unit below the head block and including a plurality of nozzles corresponding to the channels, a dispersion plate between the manifold and the head block and configured to disperse the ink in a second direction intersecting the first direction to supply the ink to the head block, and a resistance plate between the dispersion plate and the head block, formed substantially parallel to the second direction, and configured to prevent the ink from flowing in the first direction.

[0019] According to some embodiments, a first surface of the dispersion plate adjacent to the manifold can be inclined along the second direction, and the ink supplied to the dispersion plate can be supplied along the first surface between the dispersion plate and the head block.

[0020] According to some embodiments, the second surface of the dispersion plate adjacent to the head block can include a central portion and a peripheral portion positioned in the second direction with respect to the central portion, the central portion can be higher than the peripheral portion with respect to the upper surface of the head block, and the resistance plate can be at the central portion.

[0021] According to some embodiments, the resistance plates can be arranged at equal intervals along the first direction. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic perspective view illustrating an inkjet printer according to some embodiments.

[0023] Figure 2 is a cross-sectional view illustrating a substrate used in the inkjet printer of Figure 1

[0024] Figure 3 is a cross-sectional view illustrating an example of a print head unit included in the inkjet printer of Figure 1

[0025] Figure 4 is a schematic perspective view illustrating the print head unit of Figure 3

[0026] Figure 5 is a perspective view illustrating an example of a resistance plate included in the print head unit of Figure 4

[0027] Figure 6 is a view describing a function of the resistance plate of Figure 5

[0028] Figure 7 is a view illustrating comparative examples of light emitting elements supplied by the inkjet printer of Figure 1

[0029] Figure 8 is a view illustrating an example of light emitting elements supplied by the inkjet printer of Figure 1

[0030] Figure 9 is a view describing a process of manufacturing the resistance plate of Figure 5

[0031] Figure 10 is a perspective view illustrating the resistance plate included in the print head unit of Figure 4 DETAILED DESCRIPTION​​​​​​​​​

[0032] While aspects of some embodiments of the present application are open to various modifications and alternative forms, aspects of some embodiments of the present application will be described and illustrated in detail in the following description with reference to the following examples, which are not intended to limit or restrict the scope of the application, but merely to be exemplary. It should be noted that the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Unless otherwise noted, the same reference numerals are used throughout the drawings to refer to the same or like components or steps.

[0033] In all the drawings, like reference numerals refer to like elements throughout. In the drawings, the size of the structures can be exaggerated for clarity. Although the terms "first", "second", etc. can 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. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0034] It will be understood that the terms "comprises" and / or "comprising", or "includes" and / or "including" when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. Also, the term "or" as used herein is used in the inclusive sense, i.e. "and / or", unless specifically indicated otherwise. Furthermore, when a layer, film, region or plate is referred to as being "on" or "under" another layer, film, region or plate, it can be "directly" or "indirectly" on or under the other layer, film, region or plate, and one or more intervening layers, films, regions or plates can also be present. In addition, in the present application, when a part of a layer, film, region, plate, etc. is formed on another part, the direction in which the part is formed is not limited to only an upward direction, and includes a lateral direction or a downward direction. Conversely, it will be understood that when an element such as a layer, film, region or plate is referred to as being "under" another element, it can be directly under the other element, or intervening elements can also be present.

[0035] In this application, when an element (such as a first element) is described as "operatively or communicatively coupled" or "operatively or communicatively coupled to" or "connected" to another element (such as a second element), it can be directly connected to the other element or can be connected to the other element through another element (for example, a third element). Conversely, when an element (for example, a first element) is described as being "directly connected" or "directly coupled" to another element (for example, a second element), it means that there is no intervening element (for example, a third element) between the element and the other element.

[0036] Hereinafter, aspects of some embodiments of the present application will be described in greater detail with reference to the accompanying drawings. In the following description, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0037] Figure 1 is a schematic perspective view showing an inkjet printer according to some embodiments.

[0038] Referring to Figure 1 , the inkjet printer 1 (or printing apparatus) includes a stage 10 and a print head unit 20. In addition, the inkjet printer 1 can further include a moving unit 30.

[0039] The stage 10 can support a substrate 100. The stage 10 can be made of a rigid material, but the material of the stage 10 is not limited thereto. The stage 10 can have a cuboid shape, but the shape of the stage 10 is not limited thereto.

[0040] According to some embodiments, the stage 10 can be configured to move the substrate 100 using a guide rail or the like.

[0041] The substrate 100 can be positioned on the stage 10. The substrate 100 is a substrate constituting a display panel of a display image. For example, the substrate 100 can include a base substrate, a thin film transistor, an insulating layer, or the like. The substrate 100 will be described in greater detail below with reference to Figure 2 .

[0042] The print head unit 20 is positioned above the stage 10 and can discharge (or eject) ink to the substrate 100.

[0043] The moving unit 30 can be coupled to the print head unit 20 and can move the print head unit 20. According to some embodiments, the moving unit 30 can include a support member 31 for supporting the print head unit 20, a guide member 32 coupled to the support member 31 to guide movement of the print head unit 20, and a coupling member 33 coupled to the print head unit 20 and can move along the guide member 32. According to some embodiments, the inkjet printer 1 can further include an ink supply unit (e.g., an ink cartridge 40 shown in Figure 3 ) that supplies ink to the print head unit 20, and can further include a control unit that controls operations of the moving unit 30 (as well as the stage 10, the ink supply unit, or the like).

[0044] Figure 2 is a cross-sectional view showing a substrate used in the inkjet printer of Figure 1 . In Figure 2 , the substrate is positioned with respect to the inkjet printer 1 (see Figure 1) supplied ink INK briefly shows the substrate 100. For example, the substrate 100 is briefly shown based on one pixel of a display panel.

[0045] The substrate 100 can include a base substrate SUB, first and second bank patterns PW1 and PW2, first and second electrodes ETL1 and ETL2, a first insulating layer INS1, and a bank BNK.

[0046] The base substrate SUB can include a transparent insulating material to transmit light. The base substrate SUB can be a rigid substrate or a flexible substrate. The rigid substrate can be one of a glass substrate, a quartz substrate, a glass-ceramic substrate, and a crystal glass substrate, for example. The flexible substrate can be one of a film substrate including a polymer organic material and a plastic substrate.

[0047] According to some embodiments, the base substrate SUB can include a pixel circuit layer PCL, or the pixel circuit layer PCL can be positioned on the base substrate SUB.

[0048] The pixel circuit layer PCL can include a plurality of insulating layers, and a semiconductor pattern and a conductive pattern positioned between the plurality of insulating layers. Here, the semiconductor pattern and the conductive pattern can constitute a transistor, a capacitor, and a line connected thereto. The transistor, the capacitor, and the line can constitute a pixel circuit that allows the light emitting element LD to emit light, which will be described below. That is, the transistor or the like can be positioned on the base substrate SUB as a pixel circuit that allows the light emitting element LD to emit light.

[0049] The first and second bank patterns PW1 and PW2 can be positioned on the base substrate SUB (or the pixel circuit layer PCL) and can be spaced apart from each other.

[0050] The first and second bank patterns PW1 and PW2 can be positioned in the emission area EMA. To guide light emitted from the aligned light emitting elements LD to an upward direction of the substrate 100, the first and second bank patterns PW1 and PW2 serve as a support member that supports the first and second electrodes ETL1 and ETL2 so as to change a surface profile (or a cross-sectional shape) of the first and second electrodes ETL1 and ETL2. That is, the first and second bank patterns PW1 and PW2 can change the surface profile of the first and second electrodes ETL1 and ETL2.

[0051] The first bank pattern PW1 and the second bank pattern PW2 can be an inorganic insulating film including an inorganic material or an organic insulating film including an organic material. According to some embodiments, the first bank pattern PW1 and the second bank pattern PW2 can include a single organic insulating film and / or a single inorganic insulating film, but embodiments of the present application are not limited thereto. According to some embodiments, the first bank pattern PW1 and the second bank pattern PW2 can be provided in the form of a plurality of films in which at least one organic insulating film and at least one inorganic insulating film are stacked. However, the materials of the first bank pattern PW1 and the second bank pattern PW2 are not limited to the above-described example embodiments, and according to some embodiments, the first bank pattern PW1 and the second bank pattern PW2 can include a conductive material.

[0052] Each of the first bank pattern PW1 and the second bank pattern PW2 can have a trapezoidal cross-section whose width gradually decreases toward an upper portion thereof, but embodiments of the present application are not limited thereto. According to some embodiments, each of the first bank pattern PW1 and the second bank pattern PW2 can include a curved surface having a semi-elliptical or semi-circular (or semi-spherical) cross-section whose width gradually decreases upward from one surface of the base substrate SUB.

[0053] The first electrode ETL1 and the second electrode ETL2 can be positioned on the first bank pattern PW1 and the second bank pattern PW2.

[0054] Each of the first electrode ETL1 and the second electrode ETL2 can be made of a material having a certain reflectivity so as to allow light emitted from the light emitting element LD to travel in an image display direction of the display apparatus. Each of the first electrode ETL1 and the second electrode ETL2 can be made of a conductive material having a certain reflectivity. According to some embodiments, each of the first electrode ETL1 and the second electrode ETL2 can include an opaque metal, and the opaque metal can include, for example, a metal such as silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), titanium (Ti), or an alloy thereof. According to some embodiments, each of the first electrode ETL1 and the second electrode ETL2 can include a transparent conductive material, and the transparent conductive material can include a conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium gallium zinc oxide (IGZO), or indium tin zinc oxide (ITZO), or a conductive polymer such as poly(3,4-ethylenedioxythiophene) (PEDOT). When each of the first electrode ETL1 and the second electrode ETL2 includes a transparent conductive material, a separate conductive layer made of an opaque metal can be added to reflect light emitted from the light emitting element LD in the image display direction of the display apparatus.

[0055] Each of the first electrode ETL1 and the second electrode ETL2 can be provided and / or formed as a single film, but embodiments according to the present application are not limited thereto. According to some embodiments, each of the first electrode ETL1 and the second electrode ETL2 can be provided and / or formed as a plurality of films in which at least two or more materials among a metal, an alloy, a conductive oxide, and a conductive polymer are stacked. As an example, each of the first electrode ETL1 and the second electrode ETL2 can be formed as a plurality of films in which ITO, silver (Ag), and ITO are sequentially stacked.

[0056] The first insulating layer INS1 can be positioned on the first electrode ETL1 and the second electrode ETL2.

[0057] The first insulating layer INS1 can include an inorganic insulating film made of an inorganic material or an organic insulating film made of an organic material. As an example, the first insulating layer INS1 can include at least one selected from inorganic materials such as silicon nitride (SiN x ), silicon oxide (SiO x ), silicon oxynitride (SiO x N y ), and aluminum oxide (AlO x ), but embodiments according to the present application are not limited thereto. According to some embodiments, the first insulating layer INS1 can be formed as an organic insulating film capable of planarizing a support surface of the light emitting element LD.

[0058] The bank BNK can be a structure defining (or partitioning) the emission area EMA (i.e., an area in which each of the pixels provided on the display panel is disposed), and can be, for example, a pixel defining film. The bank BNK can include at least one light blocking material and / or a reflective material to prevent a light leakage defect in which light leaks between the emission area EMA and other emission areas.

[0059] An inkjet printer 1 (see Figure 1 ) can be used to supply an ink INK to the emission area EMA of the above-described substrate 100. The ink INK can be a mixture including a fluid solvent SLV and a plurality of light emitting elements LD contained (or dispersed) in the solvent SLV.

[0060] The light emitting element LD can have a shape extending in one direction. When assuming that the extending direction of the light emitting element LD is a length direction, the light emitting element LD can have one end portion (or a lower end portion) and another end portion (or an upper end portion) in the extending direction. The light emitting element LD can include a semiconductor layer positioned at both end portions thereof in the length direction and an active layer positioned between the semiconductor layers. The active layer can emit light having a wavelength of 400 nm to 900 nm.

[0061] Light-emitting elements (LDs) can be configured in various shapes. As an example, an LD can have a rod or bar shape that is relatively long in its length direction (i.e., has an aspect ratio greater than 1). An LD can, for example, include a light-emitting diode (LED) manufactured to very small dimensions, such that it has a diameter and / or length ranging from the nanometer scale to the micrometer scale.

[0062] For example, the diameter of a light-emitting element (LD) can range from about 0.5 μm to about 500 μm, and its length can range from about 1 μm to about 10 μm. However, the diameter and length of the LD are not limited to these, and the size of the LD can be changed to meet the requirements (or design conditions) of lighting devices or self-emissive display devices that use the LD.

[0063] After the light-emitting element (LD) is supplied to the emitting region EMA, an alignment signal can be applied to the first electrode ETL1 and the second electrode ETL2 to form an electric field between them, thereby aligning the LD between them. After the LD is aligned, the solvent SLV can be evaporated or removed by other methods, thus finally aligning the LD on the substrate 100.

[0064] At the same time, Figure 2 The inkjet printer 1 has already been described (see [link]). Figure 1 The ink INK is supplied to the substrate 100, and the ink INK includes a light-emitting element (LD), but the ink INK is not limited thereto. For example, as a replacement for the LD, the ink INK may include a light-conversion material (e.g., quantum dots) that converts the wavelength of light emitted from the LD to a specific wavelength and re-emits the light, or a color filter material that only blocks or transmits a specific wavelength of light emitted from the LD. The light-conversion material (e.g., quantum dots) and the color filter material may have a diameter and / or length similar to that of the LD, ranging from nanometer to micrometer scale. That is, the ink INK may include nanometer- or micrometer-scale solids in the solvent SLV.

[0065] Figure 3 It is shown that it includes Figure 1 A cross-sectional view of an example printhead unit in an inkjet printer. Figure 4 It is shown Figure 3 A schematic perspective view of the printhead unit. Figure 4 This schematically illustrates the configuration based on the printhead unit 20 (see...). Figure 3 The main body 21 (see) Figure 3 The printhead unit 20 consists of filter 23, dispersion plate 24, and head block 26. Figure 5 It is shown that it includesFigure 4 A perspective view of an example of a resistance plate in a printhead unit. For ease of description, Figure 5 The text shows a diagram based on... Figure 4 The dispersion plate 24 is in a state of being flipped 180° to the resistance plate 25.

[0066] Reference Figures 1 to 3 The printhead unit 20 can be connected to the ink cartridge 40 (or ink storage unit) via a first transfer tube 41 and a second transfer tube 42. The ink cartridge 40 can store ink (INK) and can supply ink (INK) to the printhead unit 20 via the first transfer tube 41 (or inlet). Remaining ink (INK), after being discharged from the printhead unit 20, can be supplied from the printhead unit 20 or returned to the ink cartridge 40 via the second transfer tube 42 (or outlet). That is, ink (INK) can pass through the first transfer tube 41, and a portion can be discharged from the printhead unit 20, while a portion can be recycled back into the ink cartridge 40 via the second transfer tube 42.

[0067] Each of the first transfer tube 41 and the second transfer tube 42 may be formed of a flexible hose, but is not limited thereto according to embodiments of the invention. The first transfer tube 41 and the second transfer tube 42 may be configured in various ways to ensure stable movement of ink INK.

[0068] The ink cartridge 40, the first transmission tube 41, and the second transmission tube 42 may together constitute or be referred to as an ink supply unit, although according to some embodiments, the ink supply unit may include additional components without departing from the spirit and scope of the embodiments according to this disclosure.

[0069] The printhead unit 20 may include a body 21 having an empty space therein, a manifold 22 formed or disposed in the body 21, a filter 23, a dispersion plate 24, a resistance plate 25 (or a flow deflector), a head block 26, and a nozzle unit 27.

[0070] Manifold 22 may have a space formed in the first direction DR1, may be connected to the first transmission tube 41 and the second transmission tube 42, and may guide the movement of ink INK in the first direction DR1. In addition, manifold 22 may supply ink INK in the third direction DR3 (i.e., the downward direction in which the filter 23, etc., is positioned).

[0071] Filter 23 can be positioned below manifold 22 (i.e., positioned below manifold 22 on third-direction DR3) and can filter impurities contained in ink INK. Filter 23 can prevent the nozzles NZL of nozzle unit 27 from being blocked by impurities contained in ink INK. For example, filter 23 can be a screen comprising multiple fine holes.

[0072] The dispersion plate 24 can be positioned below the filter 23 (i.e., positioned below the filter 23 in the third direction DR3) and can disperse ink INK in the second direction DR2 intersecting the first direction DR1 to supply ink INK to the head block 26. Furthermore, the dispersion plate 24 can be spaced apart from the head block 26 by a distance (e.g., a set distance or predetermined distance), and the ink INK dispersed and introduced through the relatively narrow gap between the dispersion plate 24 and the head block 26 can apply uniform pressure to the upper surface of the head block 26. That is, the dispersion plate 24 can balance the supply pressure of the ink INK. For example, the distance (e.g., a set distance or predetermined distance) GAP can be about 150 μm, but is not limited to this.

[0073] For reference, when the printhead unit 20 does not include the dispersion plate 24, the ink INK supplied from the manifold 22 to the head block 26 through the filter 23 can exert greater pressure on a specific portion of the head block 26 (e.g., the portion adjacent to the second transfer tube 42) in the direction in which the ink INK moves in the manifold 22 (i.e., the first direction DR1), thereby causing a deviation in the amount of ink INK discharged from the head block 26 (or the amount of ink discharged). To prevent or reduce the variation in the amount of ink INK discharged, the dispersion plate 24 can supply ink INK to the head block 26 by dispersing the ink INK in a second direction DR2 that intersects the direction in which the ink INK flows in the manifold 22 (i.e., the first direction DR1).

[0074] According to some embodiments, the first surface SF_U (i.e., the upper surface) of the dispersing plate 24 may be inclined in a second direction DR2 relative to a surface of the filter 23 (or the upper surface of the head block 26). In this case, the ink INK supplied through the filter 23 may be supplied between the dispersing plate 24 and the head block 26 along the first surface SF_U of the dispersing plate 24.

[0075] like Figure 4 As shown, the first surface SF_U of the dispersion plate 24 may have a shape that slopes from its central portion in a second direction DR2 and in a direction opposite to the second direction DR2. Ink INK may be dispensed along the shape of the first surface SF_U of the dispersion plate 24. Figure 4 The ink moves in the direction of DR_INK (or ink supply direction) shown, and can be introduced onto the upper surface of the head block 26 through the gap between the dispersing plate 24 and the head block 26.

[0076] According to some embodiments, the second surface SF_L of the dispersion plate 24 may include a central portion and a peripheral portion positioned relative to the central portion in the second direction DR2, and the central portion may be higher than the peripheral portion relative to the upper surface of the head block 26.

[0077] As Figure 5 indicated in FIG. 2B, the second surface SF_L of the dispersion plate 24 has a shape in which a central portion is concave, and the central portion of the second surface SF_L can have a step difference SD from a peripheral portion of the second surface SF_L. For example, the step difference SD can be about 800 µm, but is not limited thereto.

[0078] The resistance plates 25 can be positioned below the dispersion plate 24, and each of the resistance plates 25 can be formed substantially parallel to the second direction DR2. The resistance plates 25 can prevent the ink INK from flowing in the first direction DR1 (i.e., the first direction DR1 substantially perpendicular to the second direction DR2 from which the ink INK is supplied from the dispersion plate 24) below the dispersion plate 24. The resistance plates 25 can be made of a rigid material.

[0079] As Figure 5 indicated in FIG. 2B, the resistance plates 25 can be positioned at the central portion of the second surface SF_L of the dispersion plate 24. Each of the resistance plates 25 can have a height (i.e., a height in the third direction DR3) corresponding to the step difference SD between the central portion and the peripheral portion of the dispersion plate 24, and can have a shape extending in the second direction DR2. According to the arrangement of the resistance plates 25, the flow resistance of the ink INK in the second direction DR2 equal to the ink moving direction DR_INK is the same, and the flow resistance of the ink INK in the first direction DR1 substantially perpendicular to the ink moving direction DR_INK can be increased. That is, due to the resistance plates 25, it can be difficult for the ink INK to move in the first direction DR1.

[0080] According to some embodiments, the resistance plates 25 can be arranged to be spaced apart from each other by the same first distance D1 (or separation distance) in the first direction DR1. However, the arrangement of the resistance plates 25 is not limited thereto. For example, the spacing between the resistance plates 25 at the ends (i.e., the ends in the first direction DR1) of the dispersion plate 24 can be smaller than the spacing between the resistance plates 25 at the central of the area (i.e., the central of the area in the plan view) of the dispersion plate 24. Regarding the flow of the ink INK to be described with reference to Figure 6 The resistance plates 25 can be relatively densely provided at the ends (i.e., the ends in the first direction DR1) of the dispersion plate 24 with respect to the flow of the ink INK to be described with reference to

[0081] According to some embodiments, the resistance plates 25 can be integrally formed with the dispersion plate 24. However, the resistance plates 25 are not limited thereto, and the resistance plates 25 can be manufactured separately from the dispersion plate 24, and can be coupled to the dispersion plate 24. This will be described in more detail below with reference to Figure 9 .

[0082] Meanwhile, in Figure 5In the middle, the resistance plate 25 is shown as positioned in a direction perpendicular to the first direction DR1 (i.e., Figure 3 the direction of movement of the ink INK in the manifold 22) shown in the middle, but the resistance plate 25 is not limited thereto. For example, at least some of the resistance plate 25 can be positioned in a diagonal direction intersecting each of the first direction DR1 and the second direction DR2. That is, within a range capable of uniformly maintaining the density of the light emitting elements LD (or solid material) in the ink INK by reducing the flow of the ink INK under the dispersion plate 24 in the first direction DR1, the resistance plate 25 can be arranged in various directions intersecting the first direction DR1.

[0083] Referring again to Figure 3 and Figure 4 , the head block 26 can be positioned under the dispersion plate 24 (i.e., positioned under the dispersion plate 24 in the third direction DR3 with respect thereto).

[0084] The head block 26 can include a plurality of channels CH (or chambers) and piezoelectric elements PZ.

[0085] The channels CH can be connected to and communicate with the manifold 22 via the filter 23 and the dispersion plate 24. As Figure 4 shown in the middle, the channels CH can be arranged in a matrix structure in the first direction DR1 and the second direction DR2.

[0086] The piezoelectric elements PZ can be positioned adjacent to the channels CH, and can discharge the ink INK through the channels CH. As Figure 3 shown in the middle, the piezoelectric elements PZ can be arranged corresponding to the channels CH, can contract and expand in response to a signal provided from the outside (e.g., a control unit), and can press the corresponding channels CH to discharge a specific amount of ink INK.

[0087] The nozzle unit 27 can include nozzles NZL positioned under the head block 26 (i.e., positioned under the head block 26 in the third direction DR3 with respect thereto) and positioned corresponding to the channels CH of the head block 26, respectively.

[0088] The ink INK discharged through one of the nozzles NZL of the nozzle unit 27 via one of the channels CH of the head block 26 can be supplied to the emission area EMA (i.e., one of the pixels included in the display panel) described with reference to Figure 2 . That is, the ink INK can be supplied to the emission area EMA of the substrate 100 through the nozzles NZL of the nozzle unit 27.

[0089] Meanwhile, the planar size of the head block 26 can be the same as or different from the planar size of the dispersion plate 24. For example, as Figure 6As shown in FIG. 10, the length of the dispersion plate 24 in the first direction DR1 can be greater than the length of the head block 26 in the first direction DR1, and the head block 26 can be covered by the dispersion plate 24. In this case, the ink INK can be more widely dispersed by the dispersion plate 24 and supplied to the head block 26.

[0090] As described with reference to Figures 3 to 5 , the print head unit 20 can include the dispersion plate 24 and the resistance plate 25 positioned between the manifold 22 and the head block 26. Accordingly, the ink INK moving in the first direction DR1 from the manifold 22 can be dispersed in the second direction DR2 by the dispersion plate 24 to be supplied to the upper surface of the head block 26. Further, the ink INK can be prevented from flowing in the first direction DR1 from the upper surface of the head block 26 by the resistance plate 25. Accordingly, it can be prevented that solids (e.g., light emitting elements LD) in the ink INK are concentrated in a specific area, and the ink INK having a uniform concentration (e.g., the ink INK including a uniform number of light emitting elements LD) can be discharged to the substrate 100 through the passages CH of the head block 26 and the nozzles NZL of the nozzle unit 27.

[0091] Figure 6 is a view for describing the function of the resistance plate of Figure 5 . The print head unit 20 according to the comparative example (see Figure 3 ) can not include the resistance plate 25, and in this case, the flow of the ink INK (see Figure 3 ) supplied to the upper surface of the head block 26 is shown in Figure 6 . Figure 7 is a view showing a light emitting element supplied by the inkjet printer of Figure 1 and aligned on a substrate. Figure 8 is a view showing an example of a light emitting element supplied by the inkjet printer of Figure 1 and aligned on a substrate.

[0092] First, with reference to Figures 3 to 6 , the ink INK dispersed in the second direction DR2 by the dispersion plate 24 can be supplied to the upper surface of the head block 26 in the ink moving direction DR_INK.

[0093] Ink INK supplied to the region adjacent to the end (or sides) of the head block 26 in the first direction DR1 (and the direction opposite to the first direction DR1) can move toward the center of the planar region of the head block 26. The end of the head block 26 in the first direction DR1 can be closed, and the ink INK moving from the upper and lower sides of the head block 26 in the second direction DR2 can meet each other at the central portion of the head block 26 (i.e., the region between the upper and lower sides of the head block 26), and thus, ink INK can flow in the first direction DR1.

[0094] The flow of ink INK can generate vortices in the region adjacent to the end of the head block 26 in the first direction DR1. For example... Figure 6 As shown, due to the combination of the flow of ink INK in the first region A1 in the direction opposite to the first direction DR1 and the flow of ink INK in the second region A2 and the third region A3 in the first direction DR1 (and in the direction opposite to the first direction DR1), ink INK can rotate and move in the first region A1 to the third region A3.

[0095] For reference Figure 2 As described, the ink INK comprises a solvent SLV and a solid (e.g., a light-emitting element LD) contained within the solvent SLV. Due to the flow (or eddy) of the ink INK in the first direction DR1, the solvent SLV can move easily in the first direction DR1, but the solid may not move relatively easily in the first direction DR1. Due to the difference in movement characteristics between the solvent SLV and the solid, the concentration of ink INK in regions where eddies occur (e.g., in the first region A1 and the third region A3) may be lower than the concentration of ink INK in regions where eddies do not occur (or at portions corresponding to the rotation axis of the eddies, e.g., at the central portion of the second region A2). That is, the concentration of ink INK on the upper surface of the head block 26 may be non-uniform.

[0096] Reference Figure 1 , Figure 2 as well as Figures 4 to 7 , Figure 7 This shows the concentration (e.g., the number of light-emitting elements LD) of ink INK supplied to the substrate 100 at one time through the printhead unit 20 without the resistive plate 25.

[0097] like Figure 7As shown, the number of light-emitting elements (LDs) supplied to the first region A1 and the third region A3 is 50 or less, which is less than the average number of LDs (55) supplied to other regions (e.g., the second region A2). This uneven distribution of LDs can lead to brightness deviations in the display device including the substrate 100 and reduce image quality. For example, in the first region A1 and the third region A3, where the number of LDs is relatively small (and therefore the brightness is relatively low), the light spot is visible to the user.

[0098] Meanwhile, the number of light-emitting elements LD supplied to the fourth region A4, which is positioned in the opposite direction to the first direction DR1, can also be 50 or less.

[0099] Meanwhile, the printhead unit 20 according to some embodiments of the present invention may include a reference Figure 5 The described resistance plate 25 can prevent the flow of ink INK between the dispersing plate 24 and the head block 26 in the first direction DR1. Therefore, the flow of ink INK and from the first region A1 to the third region A3 (see...) can be prevented. Figure 6 The uneven concentration of ink INK caused by the flow in the ink.

[0100] Reference Figure 1 , Figure 2 as well as Figures 4 to 8 , Figure 8 The concentration (e.g., the number of light-emitting elements LD) of ink INK supplied to the substrate 100 at one time by the printhead unit 20 (i.e., the printhead unit 20 provided with the resistance plate 25) according to some embodiments of the present invention is shown.

[0101] like Figure 8 As shown, the number of light-emitting elements (LDs) supplied to the first region A1 to the third region A3 can be similar, and can also be similar to the number of light-emitting elements (LDs) supplied to other regions. That is, the relatively uniform distribution of light-emitting elements (LDs) can reduce the brightness deviation of the display device including the substrate 100, and can reduce or prevent the degradation of image quality.

[0102] For reference Figures 6 to 8 As described, the resistance plate 25 can prevent ink INK from flowing between the dispersion plate 24 and the head block 26 in the first direction DR1, and can make the ink INK concentration on the upper surface of the head block 26 uniform, thereby making the ink INK discharged through the printhead unit 20 uniform in concentration.

[0103] Figure 9 It is used to describe manufacturing Figure 5 A view of the process of the resistance plate.

[0104] ReferenceFigure 5 and Figure 9 A region of the parent substrate PLT (e.g., a metal plate) corresponding to the resistance plate 25 can be cut (or punched), and the corresponding region can be bent or folded, thereby forming the resistance plate 25. Thereafter, the parent substrate PLT can be bent based on the first dotted line L_B1 and the second dotted line L_B2 such that the parent substrate PLT can have the same or similar shape as the second surface SF_L of the dispersion plate 24. The parent substrate PLT on which the resistance plate 25 is formed can be coupled to the second surface SF_L of the dispersion plate 24 by an interference fit method or a separate coupling member.

[0105] As described with reference to Figure 9 , the resistance plate 25 can be easily manufactured through a punching and bending process for the parent substrate PLT.

[0106] Figure 10 is a perspective view showing another example of a resistance plate included in a print head unit of Figure 4 . Figure 10 shows a view corresponding to Figure 5 .

[0107] Referring to Figure 5 and Figure 10 , Figure 5 , the resistance plates 25 shown in FIGS. 1A and 1B are uniformly spaced apart from each other, but the resistance plates 25_1 shown in Figure 10 are non-uniformly arranged.

[0108] According to some embodiments, some of the resistance plates 25_1 can be positioned adjacent to the ends (or both sides) of the dispersion plate 24 in the first direction DR1 (as well as in the direction opposite to the first direction DR1).

[0109] As described with reference to Figure 3 and Figure 6 , the flow of the ink INK in the first direction DR1 between the dispersion plate 24 and the head block 26 can start in a region adjacent to the ends (or both sides) of the dispersion plate 24 in the first direction DR1 (as well as in the direction opposite to the first direction DR1), and the flow of the ink INK in the first direction DR1 can be greatest in the corresponding region.

[0110] Therefore, in order to prevent ink INK from flowing in the region adjacent to the end (or sides) of the dispersing plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1), the resistance plate 25_1 can be positioned adjacent to the end (or sides) of the dispersing plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1). According to some embodiments, the resistance plate 25_1 can be positioned only in the region adjacent to the end (or sides) of the dispersing plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1).

[0111] According to some embodiments, the distance between resistance plates 25_1 in the region adjacent to the end (or sides) of the dispersion plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1) may be different from the distance between resistance plates 25_1 in the region adjacent to the center of the planar region of the dispersion plate 24.

[0112] like Figure 10 As shown, in the region adjacent to the ends (or sides) of the dispersion plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1), the resistance plates 25_1 can be spaced apart from each other by a second distance D2, and in the region adjacent to the center of the planar region of the dispersion plate 24, the resistance plates 25_1 can be spaced apart from each other by a third distance D3. Here, the third distance D3 can be greater than the second distance D2.

[0113] For reference Figure 6 As described, in the first region A1 to the third region A3 adjacent to the ends (or sides) of the dispersing plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1), the flow of ink INK in the first direction DR1 may be relatively large. Therefore, considering that the flow of ink INK in the first direction DR1 is different for each region, in the region adjacent to the ends (or sides) of the dispersing plate 24 in the first direction DR1 (and in the direction opposite to the first direction DR1), the resistance plates 25_1 can be separated by a relatively small second distance D2, and in the region adjacent to the center of the planar region of the dispersing plate 24, the resistance plates 25_1 can be separated by a relatively large third distance D3.

[0114] For reference Figure 10 As described, the resistance plates 25_1 can be separated by non-uniform distances.

[0115] In the print head unit according to some embodiments of the present application and the inkjet printer including the same, a dispersion plate and a resistance plate are positioned between a manifold and a head block. Ink moved in a first direction from the manifold can be dispersed in a second direction by the dispersion plate to be supplied to an upper surface of the head block, and flow of the ink in the first direction from the upper surface of the head block can be prevented by the resistance plate. Accordingly, it is possible to prevent a concentration of solids (e.g., light emitting elements) in the ink from becoming non-uniform due to flow of the ink in the first direction, and it is possible to uniformly supply the light emitting elements from the print head unit to a substrate.

[0116] Effects and features of some embodiments of the present application are not limited to what has been described above in connection with the description and / or drawings of the specification. Various effects and features of some embodiments of the present application will become apparent from the following detailed description, examples, and appended claims.

[0117] Although aspects of some embodiments of the present application have been described, it is to be understood that the application is not limited to the described examples, and that various changes and modifications can be suggested to one skilled in the art, all of which are intended to be embraced within the spirit and scope of the application as defined in the appended claims.

[0118] Therefore, the technical scope of the present application should not be limited to what has been described above in the detailed description of the specification, but should be defined by the claims and their equivalents.

Claims

1. An inkjet printer, comprising: a stage; a substrate on the stage; a printhead unit above the stage and configured to discharge ink to the substrate; and an ink supply unit configured to supply the ink to the printhead unit, wherein the printhead unit comprises: a manifold configured to guide movement of the ink therein in a first direction; a head block below the manifold and comprising a plurality of passages connected to the manifold and piezoelectric elements adjacent to the passages to discharge the ink through the passages; a nozzle unit below the head block and comprising nozzles corresponding to the passages; a dispersion plate between the manifold and the head block and configured to disperse the ink in a second direction intersecting the first direction to supply the ink to the head block; and a plurality of resistance plates between the dispersion plate and the head block, formed parallel to the second direction, and configured to prevent the ink from flowing in the first direction. the ink comprises solids dispersed in a solvent, and 2. The inkjet printer according to claim 1, wherein wherein the solids are at least one selected from a light emitting element, a quantum dot, and a color filter material, each of the light emitting element, the quantum dot, and the color filter material having a diameter or length in a range from nanometer to micrometer. a first surface of the dispersion plate adjacent to the manifold is inclined along the second direction, and 3. The inkjet printer according to claim 1, wherein wherein the ink supplied to the dispersion plate is supplied between the dispersion plate and the head block along the first surface. a second surface of the dispersion plate adjacent to the head block comprises a central portion and a peripheral portion positioned in the second direction with respect to the central portion, 4. The inkjet printer according to claim 3, wherein wherein the central portion is higher than the peripheral portion with respect to an upper surface of the head block, and wherein the resistance plates are at the central portion. the resistance plates are arranged at equal intervals along the first direction.

5. The inkjet printer according to claim 4, wherein a length of the dispersion plate in the first direction is greater than a length of the head block in the first direction, and 6. The inkjet printer according to claim 4, wherein wherein the dispersion plate covers the head block in the first direction. some of the resistance plates are adjacent to both sides of the dispersion plate in the first direction.

7. The inkjet printer according to claim 4, wherein a distance between the resistance plates in an area adjacent to one side of the dispersion plate in the first direction is different from a distance between the resistance plates in an area adjacent to a central portion of a planar area of the dispersion plate.

8. The inkjet printer according to claim 4, wherein the resistance plates are formed by bending from a mother substrate parallel to a lower surface of the dispersion plate, and 9. The inkjet printer according to claim 1, wherein wherein the mother substrate is coupled to the dispersion plate. 10.A printhead unit, comprising: a manifold configured to guide movement of ink therein in a first direction; a head block below the manifold and comprising a plurality of passages connected to the manifold and piezoelectric elements adjacent to the passages to discharge the ink through the passages; a nozzle unit below the head block and comprising a plurality of nozzles corresponding to the passages; ​ a dispersion plate between the manifold and the head block and configured to disperse the ink in a second direction intersecting the first direction to supply the ink to the head block; and and a plurality of resistance plates between the dispersion plate and the head block, formed in parallel to the second direction, and configured to prevent the ink from flowing in the first direction.

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