Inkjet printing apparatus, method of printing ink, and method of manufacturing display device

Abstract

An inkjet printing apparatus, a method of printing ink, and a method of manufacturing a display device are provided. The method of printing ink includes: ejecting ink in which a plurality of particles are dispersed from an inkjet head; irradiating the ejected ink with first light and second light having different wavelengths to acquire data on first emergent light and second emergent light emitted from the ink; calculating a concentration of the particles in the ink according to the data on the first emergent light and the second emergent light; and determining whether the concentration is outside an error range of a reference value, wherein the first light has a wavelength of about 500 nm or less, and the second light has a wavelength of about 1000 nm or more.

Description

[0001] This application claims priority to and all benefits derived therefrom of Korean Patent Application No. 10-2021-0091243, filed on July 12, 2021, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure relates to an inkjet printing apparatus, a method for printing ink using the inkjet printing apparatus, and a method for manufacturing a display device. Background Technology

[0003] With the development of multimedia technology, the importance of display devices has steadily increased. In response, various types of display devices, such as organic light-emitting displays (“OLED”) and liquid crystal displays (“LCD”), are now in use.

[0004] As a display device for displaying images, there are self-emissive display devices that include light-emitting elements. Self-emissive display devices include organic light-emitting display devices that use organic materials as light-emitting materials or inorganic light-emitting display devices that use inorganic materials as light-emitting materials.

[0005] To form an organic material layer included in a display device or to house inorganic light-emitting diodes, inkjet printing equipment can be used. After printing ink in which particles are dispersed, post-processing processes can be performed to set the particles in specific areas or to form an organic material layer in which particles are dispersed.

[0006] When manufacturing display devices using inkjet printing equipment, it may be desirable for each unit of ink droplet ejected during the printing process to contain a uniform concentration of particles in order to ensure a perfect display device product. Summary of the Invention

[0007] This disclosure provides an inkjet printing apparatus capable of measuring in real time the concentration of particles in droplets or ink ejected from an inkjet head, a method for printing ink using the inkjet printing apparatus, and a method for manufacturing a display device.

[0008] However, the aspects of this disclosure are not limited to those set forth herein. These and other aspects of the disclosure will become more apparent to those skilled in the art upon reference to the detailed description of the disclosure given below.

[0009] According to one embodiment, the inkjet printing apparatus can sense changes in the concentration of particles in the ink in real time by irradiating the ink ejected from the nozzle with each type of light in different wavelengths.

[0010] In a printing ink method according to one embodiment, ink can be ejected while sensing the concentration of particles in the ink using an inkjet printing device, and a product of uniform quality can be manufactured by controlling the particle concentration of the ink injected into the inkjet head corresponding to the change in particle concentration or by controlling the particle concentration in the ink placed in a specific area.

[0011] However, the effects of this disclosure are not limited to those described above, and various other effects are included in this specification.

[0012] According to embodiments of this disclosure, a method for printing ink includes: ejecting ink from an inkjet head in which a plurality of particles are dispersed; irradiating the ejected ink with first light and second light of different wavelengths to obtain data about the first emitted light and the second emitted light emitted from the ink; calculating the concentration of particles in the ink based on the data about the first emitted light and the second emitted light; and determining whether the concentration exceeds an error range of a reference value, wherein the first light has a wavelength of about 500 nanometers (nm) or less, and the second light has a wavelength of about 1000 nm or greater.

[0013] The first emitted light can be light obtained by scattering a first light irradiated onto the ink, and the second emitted light can be light obtained by refracting a second light irradiated onto the ink.

[0014] The calculation of particle concentration may include: obtaining data on the number of particles in the ink based on data about the first emitted light; and obtaining data on the volume of the ink based on data about the second emitted light.

[0015] The method for printing ink may further include: calculating the concentration change of particles in the ink based on data about the first emitted light and the second emitted light.

[0016] The method may further include: controlling the concentration of particles in the ink injected into the inkjet head based on determining the error range of the concentration exceeding the reference value.

[0017] The method may further include setting a reference value before ejecting ink from the inkjet head.

[0018] The reference values ​​may include the normalized scattering intensity and the standard deviation of the normalized scattering intensity of the light emitted from the ink when the first light and the second light are irradiated with inks having different particle concentrations. The acquisition of data regarding the first emitted light and the second emitted light includes acquiring the normalized scattering intensity and the standard deviation of the normalized scattering intensity of the first emitted light and the second emitted light. The calculation of the particle concentration in the ink includes calculating the particle concentration in the ink by comparing the normalized scattering intensity and the standard deviation of the reference values ​​with the data regarding the first emitted light and the second emitted light.

[0019] Ink can be ejected from the inkjet head in a first direction, first light can be irradiated in a second direction perpendicular to the first direction, and second light can be irradiated after the first light is irradiated.

[0020] The first emitted light from the ink can be reflected by a reflector having a center of curvature in the path through which the ink is ejected and a curved outer surface.

[0021] Ink can be ejected from the inkjet head in a first direction, and first light and second light can be irradiated in different directions and simultaneously irradiated onto the ink.

[0022] According to embodiments of this disclosure, an inkjet printing apparatus includes: an inkjet head for jetting ink in which a plurality of particles are dispersed; a first light irradiation device and a second light irradiation device for irradiating the jetted ink with light of different wavelengths, respectively; a first sensing device on which first emitted light is incident, wherein the first emitted light is obtained by scattering first light irradiated from the first light irradiation device and incident on the ink; a second sensing device on which second emitted light is incident, wherein the second emitted light is obtained by refracting second light irradiated from the second light irradiation device and incident on the ink; and a processor on which data relating to the first emitted light and the second emitted light incident on the first and second sensing devices, respectively, are input, wherein the first light irradiated from the first light irradiation device has a wavelength of about 500 nm or less, and the second light irradiated from the second light irradiation device has a wavelength of about 1000 nm or greater.

[0023] Ink can be ejected from the inkjet head in a first direction, and the first light irradiation device can irradiate first light in a second direction perpendicular to the first direction.

[0024] The second light irradiation device can be configured to be spaced apart from the first light irradiation device in a first direction and to irradiate the second light in a second direction.

[0025] The first light irradiation device and the second light irradiation device can respectively irradiate the first light and the second light onto different areas in the path through which the ink is ejected.

[0026] The first sensing device may be disposed opposite to the first light irradiation device with respect to the path through which it ejects ink and is configured to face the first light irradiation device, and the second sensing device may be disposed opposite to the second light irradiation device with respect to the path through which it ejects ink and is configured to face the second light irradiation device.

[0027] The inkjet printing apparatus may further include a first reflector, which is spaced apart from the first light irradiation device, and the first reflector may have a center of curvature in the path through which ink is ejected and a curved outer surface, wherein the first outgoing light may be reflected from the first reflector and incident on the first sensing device.

[0028] The first sensing device may be positioned on a first side opposite to the second side where the first reflector is located, with respect to the path through which the ink is ejected.

[0029] The inkjet printing apparatus may further include a second reflector, which is spaced apart from the second light irradiation device, and the second reflector may have a center of curvature in the path through which the ink is ejected and a curved outer surface, wherein the second outgoing light may be reflected from the second reflector and incident on the second sensing device.

[0030] The second light irradiation device can be configured to irradiate the second light in a direction spaced apart from the first light irradiation device in a first direction and in a direction between the first and second directions, and the first and second light irradiation devices can respectively irradiate the ink being sprayed with the first light and the second light.

[0031] The processor can store data about the first and second emitted light based on the different concentrations of particles in the ink.

[0032] According to embodiments of the present disclosure, a method of manufacturing a display device includes: preparing a target substrate comprising a first region and a second region; ejecting a first ink containing dispersed particles therein from a first nozzle onto the first region of the target substrate; irradiating the ink ejected from the first nozzle with first light and second light of different wavelengths to obtain data regarding first emitted light and second emitted light emitted from the first ink; calculating the concentration of particles in the first ink based on the data regarding the first emitted light and second emitted light; determining whether the concentration exceeds an error range of a reference value; and ejecting a second ink containing dispersed particles therein from a second nozzle different from the first nozzle.

[0033] The first light can have a wavelength of about 500 nm or less, and the second light can have a wavelength of about 1000 nm or more.

[0034] The particles may include titanium oxide (TiO2).

[0035] The spraying of the second ink may include: when it is determined that the concentration exceeds the error range of the reference value, spraying the second ink from the second nozzle into the first area.

[0036] The first ink and the second ink sprayed onto the first area can form the first ink pattern.

[0037] The spraying of the second ink may include: spraying the second ink from the second nozzle into the second area when it is determined that the concentration does not exceed the error range of the reference value.

[0038] The first ink sprayed onto the first region can form a first ink pattern, and the second ink sprayed onto the second region can form a second ink pattern that is different from the first ink pattern.

[0039] The method of manufacturing a display device may further include: spraying a third ink containing dispersed particles from a third nozzle, which is different from the first nozzle, into the first region.

[0040] The method of manufacturing a display device may further include: spraying a third ink containing dispersed particles from a third nozzle, which is different from the first nozzle, into a second region.

[0041] The method of manufacturing a display device may further include: irradiating a first light and a second light onto a third ink ejected from a third nozzle to obtain data on a third emitted light and a fourth emitted light emitted from the third ink, and calculating the concentration of particles in the third ink based on the data on the third emitted light and the fourth emitted light, and determining whether the concentration exceeds the error range of a reference value. Attached Figure Description

[0042] The above and other aspects and features of this disclosure will become more apparent from the detailed description of embodiments thereof with reference to the accompanying drawings, in which:

[0043] Figure 1 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to one embodiment;

[0044] Figure 2 This is a schematic diagram illustrating the construction of an ink concentration measuring device according to one embodiment;

[0045] Figure 3 and Figure 4 This is a schematic diagram showing the scattering of light that strikes particles dispersed in ink;

[0046] Figure 5 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to one embodiment;

[0047] Figure 6 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to another embodiment;

[0048] Figure 7 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to yet another embodiment;

[0049] Figure 8 It is shown that Figure 7A schematic diagram of the propagation of light reflected by a reflector in an inkjet printing device;

[0050] Figure 9 and Figure 10 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to another embodiment;

[0051] Figure 11 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to another embodiment;

[0052] Figure 12 This is a flowchart illustrating a method of printing ink using an inkjet printing apparatus according to one embodiment;

[0053] Figures 13 to 16 This is a schematic diagram showing a method for printing inks according to one embodiment;

[0054] Figure 17 and Figure 18 It is a graph showing emitted light data based on the concentration of particles in the ink measured using inkjet printing equipment;

[0055] Figure 19 This is a flowchart illustrating a method for printing ink using an inkjet printing apparatus according to another embodiment;

[0056] Figure 20 This is a diagram illustrating the arrangement of a plurality of nozzles included in the inkjet head of an inkjet printing apparatus according to one embodiment;

[0057] Figure 21 It shows from Figure 20 A diagram showing the ink ejection from multiple nozzles included in an inkjet head;

[0058] Figure 22 This is a flowchart illustrating the sequence of some steps in a method for printing ink according to one embodiment;

[0059] Figure 23 It is shown Figure 22 A flowchart showing the sequence of steps;

[0060] Figure 24 It is shown Figure 23 A diagram of one step;

[0061] Figure 25 This is a flowchart illustrating a method of manufacturing a display device according to one embodiment;

[0062] Figures 26 to 29 This is a cross-sectional view illustrating a method for manufacturing a display device using printing ink according to one embodiment;

[0063] Figure 30This is a cross-sectional view showing a portion of a display device according to one embodiment;

[0064] Figure 31 This is a flowchart illustrating a method for manufacturing a display device according to another embodiment; and

[0065] Figure 32 and Figure 33 It is shown Figure 31 A cross-sectional view of one step in a method for manufacturing a display device. Detailed Implementation

[0066] The invention will now be described more fully below with reference to the accompanying drawings, in which preferred embodiments of the invention are illustrated. However, the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and that they will fully convey the scope of the invention to those skilled in the art.

[0067] It will also be understood that when a layer is referred to as being "on" another layer or substrate, it may be directly on the other layer or substrate, or an intervening layer may be present. Throughout the specification, the same reference numerals indicate the same parts.

[0068] 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 used only to distinguish one element from another. For example, the first element discussed below may be referred to as the second element without departing from the teachings of the invention. Similarly, the second element may also be referred to as the first element.

[0069] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, “a,” “the,” and “at least one” do not indicate a limitation of quantity and are intended to include both the singular and the plural unless the context clearly indicates otherwise. For example, “an element” has the same meaning as “at least one element” unless the context clearly indicates otherwise. “At least one” should not be construed as a limiting “a.” “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It will be further understood that, when used in this specification, the terms “comprising” or “including” specify the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or combinations thereof. Taking into account the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., limitations of the measurement system), as used herein, “about” or “approximately” includes the stated value and means within an acceptable deviation range of that particular value as determined by one of ordinary skill in the art. For example, "approximately" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value. Embodiments will be described below with reference to the accompanying drawings.

[0070] Figure 1 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to one embodiment. Figure 2 This is a schematic diagram illustrating the construction of an ink concentration measuring device according to one embodiment.

[0071] refer to Figure 1 and Figure 2 The inkjet printing equipment 10 includes an inkjet head PA and an ink density measuring device 100. The inkjet head PA can spray ink containing multiple dispersed particles through a nozzle (not shown). Figure 3 The ink DL (hereinafter referred to as "PT") is sprayed from the inkjet printhead PA onto the printing target object, and can form a layer or pattern on the target object depending on the type of ink DL material. In the accompanying drawings, only the inkjet printhead PA and the ink density measuring device 100 that spray ink DL from it are shown in the inkjet printing apparatus 10, but the inkjet printing apparatus 10 may further include devices other than the inkjet printhead PA and the ink density measuring device 100.

[0072] The ink concentration measuring device 100 includes a light irradiation device 110, a sensing device 130, and a processor 150. The ink concentration measuring device 100 can acquire optical data of the ink DL (dielectric density) as a measurement target using the light irradiation device 110 and the sensing device 130, and can sense the concentration and concentration changes of particles in the ink DL based on the acquired data. According to one embodiment, the ink concentration measuring device 100 can acquire information such as the particles included in the ink DL as a measurement target (…). Figure 3 The data includes the change in the quantity of “PT” in the ink and the droplet volume and velocity of the ink DL, and the concentration change of dispersed particles per unit droplet of ink DL can be determined based on this data.

[0073] According to one embodiment, the ink concentration measuring device 100 can measure ink DL in which multiple particles PT are dispersed, and can be ink DL ejected from an inkjet head PA. In an embodiment, the inkjet head PA can include multiple nozzles or ejection units to simultaneously eject ink DL from each nozzle. The ink DL ejected from the inkjet head PA can include solvent ( Figure 3 The ink (DL) contains "SV" and multiple particles PT dispersed therein, and the ejected ink can be sprayed onto a printing object (e.g., a target substrate) to form a layer or pattern including the particles PT. To maintain the uniform quality of the layer or pattern formed by the ink DL, it is desirable that the number or concentration of particles PT per unit droplet of the ink DL ejected from the inkjet head PA is uniform during repeated printing processes. Specifically, particles PT dispersed in the liquid ink DL may precipitate in the ink DL with repeated processes, and the number of particles PT per unit droplet of the ink DL ejected from the inkjet head PA may change.

[0074] According to one embodiment, an ink concentration measuring device 100 can be embedded in an inkjet printing apparatus 10 including an inkjet head PA, and can sense in real time the number of particles PT per unit droplet of ink DL ejected from the inkjet head PA or the concentration change of particles PT in the ink DL while performing the printing process of the inkjet head PA. The ink concentration measuring device 100 can provide feedback to the inkjet head PA based on the sensed concentration change of particles PT to maintain a uniform concentration of particles PT in the ink DL ejected from the inkjet head PA.

[0075] The light irradiation device 110 can irradiate the ink DL ejected from the inkjet head PA. The light irradiation device 110 can irradiate an irradiation area SA located in the path through which the ink DL is ejected from the inkjet head PA, and the light L irradiated by the light irradiation device 110 can be incident on the ink DL while passing through the irradiation area SA. The light irradiation device 110 can be positioned at a location capable of irradiating the ink DL ejected from the inkjet head PA along its path. For example, when ink DL is ejected from the inkjet head PA in a first direction DR1, the light irradiation device 110 can irradiate the light L in a direction different from the first direction DR1. For example, the light irradiation device 110 can be positioned in a second direction DR2, spaced apart from the path through which it ejects ink DL, to irradiate the light L in a second direction DR2 perpendicular to the first direction DR1. The light irradiation device 110 may not be positioned in the first direction DR1, where ink DL is ejected from the inkjet head PA, and may be positioned in the second direction DR2, spaced apart from the lower part of the inkjet head PA. However, this disclosure is not limited thereto, and the arrangement of the light irradiation device 110 and the inkjet head PA may differ from the arrangement shown in the accompanying drawings.

[0076] The light L irradiated by the light irradiation device 110 onto the ink DL can be reflected, refracted, or scattered by the ink DL, and the emitted light SL (hereinafter referred to as "emitted light from the ink DL") can be incident on the sensing device 130. The sensing device 130 can sense the amount, intensity, and scattering intensity of the emitted light SL from the ink DL.

[0077] The light irradiation device 110 and the sensing device 130 can be positioned for easy illumination of the ink DL with light L or for sensing of the emitted light SL. For example, when ink DL is ejected from the inkjet head PA in a first direction DR1, the light irradiation device 110 can irradiate light L in a direction different from the first direction DR1, and the sensing device 130 can be positioned opposite the light irradiation device 110 with respect to the path through which it ejects ink DL. For example, when the light irradiation device 110 is positioned on one side of the second direction DR2 and spaced apart from the path through which it ejects ink DL, the sensing device 130 is positioned on the other side of the second direction DR2 and spaced apart from the path through which it ejects ink DL, such that the light irradiation device 110 and the sensing device 130 can face each other. Although the figures show the light irradiation device 110 and the sensing device 130 positioned in opposite directions with respect to the ejection path of ink DL, this disclosure is not limited thereto. In some embodiments, the ink density measuring device 100 may further include means capable of reflecting or converging the emitted light SL from the ink DL in a particular direction, and in this case, the arrangement of the sensing device 130 can be changed.

[0078] Light L incident from the light irradiation device 110 can be scattered or refracted by particles PT dispersed in the ink DL while passing through the ink DL. The scattering intensity of light L incident on the ink DL can vary depending on the amount or concentration of particles PT dispersed in the ink DL. When the light irradiation device 110 irradiates light L within a predetermined intensity range or wavelength band, the intensity of the emitted light SL sensed by the sensing device 130 and the scattering intensity can vary depending on the amount or concentration of particles PT dispersed in the ink DL.

[0079] Figure 3 and Figure 4 This is a schematic diagram showing the scattering of light that shines on particles dispersed in ink. Figure 3 and Figure 4 Each of the images shows light L irradiated from light irradiation device 110 being scattered by ink DL. Figure 3 Example: The ratio of dispersed particles PT in ink DL Figure 4 The example shown illustrates a case where the number of dispersed particles PT in the ink DL is small.

[0080] refer to Figure 3 and Figure 4 The ink DL ejected from the inkjet printhead PA can be in a solution or colloidal state. The ink DL may include a solvent SV and multiple particulate PTs dispersed in the solvent SV. In one embodiment, the solvent SV may be acetone, water, ethanol, toluene, propylene glycol (“PG”) or propylene glycol methyl acetate (“PGMA”), triethylene glycol monobutyl ether (“TGBE”), diethylene glycol monophenyl ether (“DGPE”), amide solvent, dicarbonyl solvent, diethylene glycol dibenzoate, tricarbonyl solvent, triethyl citrate, phthalate solvent, benzyl butyl phthalate, di(2-ethylhexyl) phthalate, di(2-ethylhexyl) isophthalate, or ethylene glycol phthalate, etc., but not limited to these. The multiple particulate PTs may be inorganic or organic particles, such as quantum dots, scatterers, or inorganic semiconductor particles. The type of particulate PTs dispersed in the ink DL and ejected may vary depending on the type of layer or pattern to be formed using the inkjet printhead PA. In this embodiment, the particles PT dispersed in the ink DL and ejected by the inkjet head PA can be scatterers such as titanium oxide (TiO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), indium oxide (In2O3), zinc oxide (ZnO), tin oxide (SnO2), or quantum dot materials such as acrylic resin or polyurethane resin, group IV nanocrystals, group II-VI compound nanocrystals, group III-V compound nanocrystals, group IV-VI compound nanocrystals, or combinations thereof. Alternatively, when the particles PT are inorganic semiconductor particles, the particles PT can be inorganic semiconductor particles comprising gallium (Ga) as an inorganic light-emitting element having a micron to nanometer size.

[0081] Regardless of the type of particles PT dispersed in the ink DL, the intensity or amount of scattered light obtained by scattering light L incident on the ink DL and the scattering intensity can vary depending on the number or concentration of particles PT. As the number of particles PT in the ink DL increases, the scattering intensity of light L incident on the ink DL, as well as the intensity of the scattered light and the scattering intensity, can increase. The ink concentration measuring device 100 may further include a processor 150 for sensing or calculating changes in the concentration of particles PT in the ink DL based on optical data obtained from the sensing device 130.

[0082] Processor 150 can receive data about emitted light SL incident on sensing device 130. Processor 150 can sense the concentration change of particles PT in ink DL based on the input emitted light data. Processor 150 may include an algorithm for selecting data about emitted light SL from ink DL from optical data acquired by sensing device 130 and an algorithm for calculating the concentration change of particles PT in ink DL based on the data about emitted light SL. For example, not only emitted light SL from ink DL, but also light L irradiated from light irradiation device 110 according to the settings of sensing device 130 and light irradiation device 110 can be incident on sensing device 130. Processor 150 can select data about emitted light SL from ink DL from the data of light incident on sensing device 130 based on data such as the travel path, intensity, and scattering intensity of light L irradiated from light irradiation device 110. The concentration change of particles PT in ink DL can be sensed based on the data about emitted light SL from ink DL.

[0083] The concentration measurement of particles PT in the ink DL performed by the ink concentration measuring device 100 is to sense the concentration change of particles PT in the ink DL while performing the ink DL ejection process in the inkjet head PA, and to maintain that the ink DL ejected by the inkjet head PA includes a uniform number of particles PT per unit droplet. In the above process, the data that can be acquired by the sensing device 130 is data on the intensity and amount of emitted light SL from the ink DL and the scattering intensity. The ink concentration measuring device 100 can extract or calculate data on the number and concentration of particles PT per unit droplet of the ink DL based on the acquired optical data, and determine whether the concentration change of particles PT exceeds a reference value based on the data, so that an algorithm for controlling the inkjet head PA can be executed. The concentration measurement method performed by the ink concentration measuring device 100 will be described later with reference to other figures.

[0084] On the other hand, the change data of particle PT in the ink DL sensed by the ink density measuring device 100 is the change in the number of particle PT per unit droplet of ink DL ejected from the inkjet head PA, and can also be the change data of particle PT concentration in the ink DL. The change in particle PT concentration in the ink DL ejected from the inkjet head PA can be related to each of the droplet volume of the ink DL ejected in one ejection and the number of particle PT included in the ink DL ejected in one ejection. The number of particle PT in the ink DL ejected in one ejection may change when particle PT settles in the ink DL flowing in the channels included in the inkjet head PA. In addition, the number of particle PT ejected per unit time may also change when the volume of the ink DL ejected in one ejection changes due to the formation of foreign matter in the nozzles from which the ink DL is ejected in the inkjet head PA. These changes may cause changes in the concentration of particle PT in the ink DL ejected in one ejection from the inkjet head PA, which may result in uneven quality of the layer or pattern formed using the inkjet head PA. The ink density measuring device 100 can sense the change in particle PT concentration in the ink DL ejected in one ejection from the inkjet head PA in real time and provide feedback to the inkjet head PA.

[0085] An ink concentration measuring device 100 according to one embodiment may include a plurality of light irradiation devices 110 and a plurality of sensing devices 130, enabling them to acquire different data regarding ink DL. The ink concentration measuring device 100 can sense the concentration change of particle PT per unit droplet of ink DL by means of data relating to the volume and velocity of ink DL ejected from the inkjet head PA in a single stroke, and to the number of particles PT included in the ink DL, and can feed this change back to the inkjet head PA.

[0086] Figure 5 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to one embodiment.

[0087] refer to Figure 5 According to one embodiment, the ink concentration measuring device 100 may include a plurality of light irradiation devices 110 (111 and 113) that irradiate different lights L1 and L2, and a plurality of sensing devices 130 (131 and 133) that sense the emitted light SL1 and SL2 from the ink DL by means of the light L1 and L2 irradiated from the light irradiation devices 111 and 113, respectively. The different light irradiation devices 110 and sensing devices 130 may acquire different data from the ink DL ejected by the inkjet head PA, respectively.

[0088] According to one embodiment, the light irradiation device 110 may include a first light irradiation device 111 and a second light irradiation device 113 that irradiate light of different wavelengths. The sensing device 130 may include a first sensing device 131 and a second sensing device 133, wherein a first emitted light SL1, irradiated from the first light irradiation device 111 and emitted from the ink DL, is incident on the first sensing device 131, and a second emitted light SL2, irradiated from the second light irradiation device 113 and emitted from the ink DL, is incident on the second sensing device 133. The first light irradiation device 111 and the first sensing device 131 may form a pair for acquiring data related to the number of particles PT dispersed in the ink DL, and the second light irradiation device 113 and the second sensing device 133 may form a pair for acquiring data related to the volume and velocity of the ink DL ejected in a single spray.

[0089] As described above, the first light irradiation device 111 and the second light irradiation device 113 can be respectively configured to irradiate light L1 and L2 in a direction different from the first direction DR1 from which ink DL is ejected from the inkjet head PA. For example, each of the first light irradiation device 111 and the second light irradiation device 113 can be configured such that one side of the first light irradiation device 111 and the second light irradiation device 113 is spaced apart from the path through which the ink DL is ejected from the inkjet head PA. The first light irradiation device 111 and the second light irradiation device 113 can respectively use light L1 and L2 to irradiate irradiation areas SA1 and SA2 disposed in the path through which they eject ink DL in the second direction DR2. The first light irradiation device 111 and the second light irradiation device 113 can be disposed on one side of the path through which they eject ink DL in the same direction, and can be disposed parallel to each other in the first direction DR1, but this disclosure is not limited thereto. In some embodiments, the first light irradiation device 111 and the second light irradiation device 113 may not be disposed parallel to each other, or may be disposed opposite to each other with respect to the path through which they eject ink DL.

[0090] The accompanying drawings illustrate that the first light irradiation device 111 is positioned spaced apart from one side of the second light irradiation device 113 in the first direction DR1, and is therefore positioned closer to the inkjet head PA than the second light irradiation device 113. In the irradiation areas SA1 and SA2 disposed in the path in which ink DL is ejected, the first irradiation area SA1 irradiated by the first light L1 of the first light irradiation device 111 can be positioned closer to the inkjet head PA than the second irradiation area SA2 irradiated by the second light L2 of the second light irradiation device 113. However, this disclosure is not limited thereto, and in some embodiments, the second light irradiation device 113 may be positioned closer to the inkjet head PA than the first light irradiation device 111.

[0091] Multiple sensing devices 130 can be positioned at locations where emitted light SL1 and SL2 from ink DL can be incident upon them. For example, ink DL can be ejected from inkjet head PA in a first direction DR1, a first light irradiation device 111 and a second light irradiation device 113 can irradiate light L1 and L2 in a second direction DR2, and sensing devices 130 can be positioned opposite light irradiation device 110 with respect to the path through which they eject ink DL. A first sensing device 131 can be spaced apart from the first light irradiation device 111 in the second direction DR2 to be positioned opposite to the path through which it ejects ink DL, and a second sensing device 133 can be spaced apart from the second light irradiation device 113 in the second direction DR2 to be positioned opposite to the path through which it ejects ink DL. The first light irradiation device 111 and the second light irradiation device 113 can face the first sensing device 131 and the second sensing device 133 respectively in the second direction DR2.

[0092] According to one embodiment, the first light irradiation device 111 and the second light irradiation device 113 can irradiate light of different wavelengths. For example, the first light irradiation device 111 can irradiate a short-wavelength first light L1 with a wavelength of 500 nanometers (nm) or less, and the second light irradiation device 113 can irradiate a long-wavelength second light L2 with a wavelength of approximately 1000 nm or greater. The light L1 and L2 irradiated onto the ink DL can be refracted or scattered by the ink DL and the particles PT in the ink DL to be incident on the sensing device 130. Since the shorter the wavelength of light L1 and L2, the more light L1 and L2 can be scattered by the particles PT, the short-wavelength first light L1, whose wavelength is shorter than the long-wavelength wavelength of the second light L2, has an advantage in measuring the change in the number of particles PT in the ink DL. On the other hand, the long-wavelength second light L2 has an advantage in measuring the size, volume, and velocity of the ejected ink DL. In some embodiments, the first light L1 irradiated by the first light irradiation device 111 may be a first incident light incident on the ink DL, and the first outgoing light SL1 emitted from the ink DL from the first light L1 may be light scattered from the ink DL. The second light L2 irradiated by the second light irradiation device 113 may be a second incident light incident on the ink DL, and the second outgoing light SL2 emitted from the ink DL from the second light L2 may be light refracted by the ink DL. The ink concentration measuring device 100 may include a first light irradiation device 111 and a second light irradiation device 113 that respectively emit light L1 and L2 of different wavelengths, and may respectively acquire data related to the number of particles PT in the ink DL and data related to the size, volume, and velocity of the ink DL ejected from the inkjet head PA.

[0093] A first emitted light SL1, generated from the first light L1 scattered by the ink DL and irradiated by the first light irradiation device 111, can be incident on the first sensing device 131, from which data related to the number of particles PT in the ink DL can be obtained. The stronger the intensity and scattering intensity of the first emitted light SL1 compared to the first light L1, the larger the number of particles PT in the ink DL can be. The weaker the intensity and scattering intensity of the first emitted light SL1, the smaller the number of particles PT in the ink DL can be. A second emitted light SL2, generated from the second light L2 refracted by the ink DL and irradiated by the second light irradiation device 113, can be incident on the second sensing device 133, from which data related to the size, volume, and velocity of particles in the ink DL can be obtained.

[0094] The processor 150 of the ink concentration measuring device 100 can sense changes in the concentration of particles PT in the ink DL based on data about emitted light SL1 and SL2 acquired from the first sensing device 131 and the second sensing device 133. The data about emitted light SL1 and SL2 acquired by the first sensing device 131 and the second sensing device 133 respectively can be data about light intensity, scattering intensity, and incident direction of light, etc. When performing a process of ejecting ink DL from the inkjet head PA, the processor 150 can process the data obtained by irradiating the ink DL with light for each ejection process, calculate the difference compared to an initial value or a preset value, and calculate the concentration of particles PT in the ink DL.

[0095] For example, when data relating to the concentration of PT particles in the ink DL is set using data relating to the size, volume, velocity, and quantity of the ink DL particles ejected in the initial ejection process of the inkjet head PA, the processor 150 can calculate data relating to the amount of change in the concentration of PT particles in the ink DL based on data relating to the size, volume, velocity, and quantity of the ink DL particles as changed for each ejection process. Alternatively, when the processor 150 stores values ​​relating to the desired size, volume, velocity, and quantity of PT particles for a single ejection of the ink DL in the printing process of the inkjet head PA, the processor 150 can calculate data relating to the concentration of PT particles in the ink DL by comparing data about the ink DL acquired for each ejection process with the stored data. This will be described in more detail later with reference to other accompanying drawings.

[0096] According to one embodiment, an inkjet printing apparatus 10 may include an ink concentration measuring device 100, which senses in real time the concentration of particles PT in the ink DL ejected from the inkjet head PA, thereby uniformly maintaining the concentration of particles PT in the ink DL during repeated printing processes. When a layer or pattern including particles PT is formed by using the inkjet printing apparatus 10, the product formed by the printing process has the advantage of uniformly maintaining the quality of the layer and pattern.

[0097] Figure 6 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to another embodiment.

[0098] refer to Figure 6 In an inkjet printing apparatus 10 according to one embodiment, the second light irradiation device 113 and the second sensing device 133 may be positioned closer to the inkjet head PA than the first light irradiation device 111 and the first sensing device 131. When ink DL is ejected from the inkjet head PA in the first direction DR1 and the irradiation areas SA1 and SA2 irradiated by the light irradiation device 110 using light L1 and L2 respectively are located in the ejection path of the ink DL, in this embodiment, the second irradiation area SA2 may be positioned closer to the inkjet head PA than the first irradiation area SA1. When the ink density measuring device 100 of the inkjet printing apparatus 10 includes the first light irradiation device 111 and the second light irradiation device 113 and acquires various data of the ink DL by irradiating light L1 and L2 of different wavelengths, their relative arrangement is not particularly limited. Except for the difference in the relative arrangement between the second light irradiation device 113 and the second sensing device 133 and the first light irradiation device 111 and the first sensing device 131, this embodiment is similar to... Figure 5 The embodiments are the same.

[0099] Because the second light irradiation device 113 and the second sensing device 133 are positioned closer to the inkjet head PA, the inkjet printing apparatus 10 has the advantage of being able to more easily acquire data related to the size, volume, and velocity of the ink DL ejected from the inkjet head PA. After the ink DL is ejected from the inkjet head PA, the physical properties of the ink droplets may change due to the printing target object or other external factors while being placed on the target substrate. The data related to the number of particles PT in the ink DL that can be acquired from the first light irradiation device 111 and the first sensing device 131 can be almost constant and independent of the physical properties of the ink droplets after being ejected from the inkjet head PA. Therefore, in the inkjet printing apparatus 10, the second light irradiation device 113 and the second sensing device 133 can be positioned closer to the inkjet head PA to acquire data of the second emitted light SL2, which is data about the size, volume, and velocity of the ink DL immediately after being ejected from the inkjet head PA.

[0100] Figure 7 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to yet another embodiment. Figure 8 It is shown that Figure 7 A schematic diagram of the propagation of light reflected by a reflector in an inkjet printing device.

[0101] refer to Figure 7 and Figure 8 In an inkjet printing apparatus 10 according to one embodiment, the ink concentration measuring device 100 may further include a reflector 190 capable of converging the emitted light SL from the ink DL, which is irradiated by the light irradiation device 110, onto a specific area.

[0102] Reflector 190 may have a semi-circular shape with a curved outer surface and may surround the ejection path through which ink DL is ejected from inkjet head PA. The ink DL ejected from inkjet head PA may be ejected to pass through the center of curvature of reflector 190, and light L irradiated from light irradiation device 110 may be scattered or refracted in the ink DL to incident on reflector 190 as outgoing light SL. Reflector 190 may include a material with high reflectivity to reflect the outgoing light SL from ink DL in a direction opposite to the incident direction of light L.

[0103] The reflector 190 can be positioned to reflect the emitted light SL from the ink DL. For example, in an embodiment where the light irradiation device 110 is positioned spaced apart from the ink DL's ejection path in the second direction DR2, the reflector 190 can be formed to be curved toward the side opposite to the light irradiation device 110 with respect to the ink DL's ejection path. The reflector 190 can be positioned such that its center of curvature is located on the ink DL's ejection path, and the reflector 190 can have a convex shape with respect to the ink DL's ejection path in a direction opposite to the direction in which the light irradiation device 110 is positioned. The emitted light SL from the ink DL, irradiated from the light irradiation device 110, can travel toward the recessed inner side of the reflector 190.

[0104] Additionally, the emitted light SL can be reflected from the reflector 190 in the direction in which the light irradiation device 110 is installed. Figure 1 and Figure 5Unlike other embodiments, the emitted light SL points in the same direction as the light irradiation device 110, and therefore, according to one embodiment, the sensing device 130 can be positioned in the same direction as the light irradiation device 110 with respect to the ink DL ejection path. The reflector 190 can reflect the emitted light SL from the ink DL toward any region (e.g., the sensing region SS) within the portion in which the light irradiation device 110 is located, and the sensing device 130 can sense the emitted light SL incident on the sensing region SS. The light irradiation device 110 and the sensing device 130 may not face each other in the second direction DR2, but can be positioned parallel to each other on one side of the ink DL ejection path.

[0105] Reflector 190 can reflect the light L irradiated from light irradiation device 110 and the emitted light SL from ink DL toward sensing area SS, and thus can cause a light convergence effect. Sensing device 130 can acquire data about the emitted light SL from ink DL by sensing only the light incident on the sensing area SS to which the light reflected by reflector 190 is directed. The ink density measuring device 100 of inkjet printing equipment 10 further includes reflector 190 and has the advantage of improving the accuracy and precision of the data acquired by sensing device 130.

[0106] Figure 9 and Figure 10 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to another embodiment.

[0107] refer to Figure 9 and Figure 10 In an inkjet printing apparatus 10 according to one embodiment, an ink concentration measuring device 100 may include at least one reflector 190 (191 and 193) to improve the accuracy and precision of the data acquired by the first sensing device 131 and the second sensing device 133.

[0108] exist Figure 9 In one embodiment, the ink concentration measuring device 100 may include a reflector 190 and may be configured to face the first light irradiation device 111. The first light irradiation device 111 and the reflector 190 may be configured to face each other in the second direction DR2, and the first sensing device 131 may be arranged parallel to the first light irradiation device 111 on one side of the ink DL ejection path, without facing each other in the second direction DR2. On the other hand, as in Figure 6 In one embodiment, the second light irradiation device 113 and the second sensing device 133 may be configured to face each other in the second direction DR2.

[0109] exist Figure 10In one embodiment, the ink concentration measuring device 100 may include a first reflector 191 and a second reflector 193. The first reflector 191 may be configured to face the first light irradiation device 111, and the second reflector 193 may be configured to face the second light irradiation device 113. The first sensing device 131 and the first light irradiation device 111 may be arranged parallel to each other on one side of the ink DL ejection path, without facing each other in the second direction DR2. The second sensing device 133 and the second light irradiation device 113 may be arranged parallel to each other on one side of the ink DL ejection path, without facing each other in the second direction DR2.

[0110] Figure 11 This is a schematic diagram illustrating the operation of an inkjet printing apparatus according to another embodiment.

[0111] refer to Figure 11 In an inkjet printing apparatus 10 according to one embodiment, a first light irradiation device 111 and a second light irradiation device 113 can respectively irradiate the same irradiation area SA using light L1 and L2. When the first light irradiation device 111 and the second light irradiation device 113 respectively irradiate light L1 and L2 to guide in different directions, although the first light irradiation device 111 and the second light irradiation device 113 irradiate the same irradiation area SA using light L1 and L2, different sensing devices 131 and 133 can respectively sense different emitted light SL1 and SL2. When one light irradiation device 111 irradiates ink DL using light L1 by bypassing the light propagation path of the other light irradiation device 113, different light irradiation devices 111 and 113 can simultaneously irradiate ink DL located in the same area using light L1 and L2, and different sensing devices 131 and 133 can respectively acquire data of emitted light SL1 and SL2.

[0112] For example, when ink DL is ejected from inkjet head PA and located in any irradiation area SA, the first light irradiation device 111 can irradiate a first light L1 in the second direction DR2. The first light L1 irradiated in the second direction DR2 can be scattered from the ink DL and can be guided toward reflector 190. When the first emitted light SL1 reflected from reflector 190 is incident on a sensing area (not shown), the first sensing device 131 can sense the first emitted light SL1. The first sensing device 131 can be arranged parallel to the first light irradiation device 111 on one side of the ejection path of ink DL. The first light L1 irradiated from the first light irradiation device 111 can be a laser with a short wavelength, and the data about the first emitted light SL1 obtained from the first sensing device 131 can be data related to the number of particles PT in ink DL.

[0113] and Figure 5Unlike other embodiments, when ink DL is ejected from the inkjet head PA and located in any irradiation area SA, the second light irradiation device 113 can irradiate the second light L2 in the direction between the first direction DR1 and the second direction DR2. The second light L2 irradiated by the second light irradiation device 113 may not be guided toward the reflector 190, but may be guided toward the second sensing device 133 which is set to face the second light irradiation device 113.

[0114] When the second light irradiation device 113 is positioned spaced apart from the first light irradiation device 111 in the first direction DR1 and irradiates the irradiation area SA of the first light irradiation device 111 located in the second direction DR2 with the second light L2, the second light L2 can be guided from the lower side of the first light irradiation device 111 (e.g., the other side in the first direction DR1) to the upper side of the reflector 190 (e.g., one side in the first direction DR1). The second sensing device 133 can be positioned facing the second light irradiation device 113 with respect to the irradiation area SA, and can be positioned on the upper side of the reflector 190 (one side in the first direction DR1). The second light L2 guided toward the irradiation area SA may not be guided to the reflector 190, but may be guided to the second sensing device 133. The second light L2 irradiated from the second light irradiation device 113 may be a laser with a long wavelength, and the data about the second emitted light SL2 obtained from the second sensing device 133 may be data related to the size, volume, and speed of the ink DL.

[0115] When the first light irradiation device 111 irradiates the reflector 190 with the first light L1, the first light irradiation device 111 and the first sensing device 131 can be arranged parallel to each other on one side of the ink DL ejection path. On the other hand, since the second light irradiation device 113 irradiates the second light L2 in an oblique direction so as not to be guided to the reflector 190, the second light irradiation device 113 and the second sensing device 133 can be arranged opposite to each other with respect to the ink DL ejection path and can face each other. In the inkjet printing apparatus 10 according to the embodiment, different light irradiation devices 111 and 113 can simultaneously irradiate the ink DL located in the same irradiation area SA with light L1 and L2, and can acquire data of the emitted light SL1 and SL2. The light irradiation devices 111 and 113 and the sensing devices 131 and 133 can have corresponding arrangements.

[0116] The method of printing ink using inkjet printing equipment 10 will be further described below with reference to other accompanying drawings.

[0117] Figure 12 This is a flowchart illustrating a method of printing ink using an inkjet printing apparatus according to one embodiment.

[0118] refer to Figure 12According to one embodiment, a method for printing ink using an inkjet printing apparatus 10 includes ejecting ink DL from an inkjet head PA (step S10), irradiating the ejected ink DL with light L1 and L2 to obtain data of emitted light SL1 and SL2 (step S20), and determining whether the concentration of particles PT in the ink DL deviates from a reference value (step S30). In the ink concentration measuring device 100, the processor 150 senses the concentration and concentration change of particles PT in the ink DL, and based on whether the sensed concentration value deviates from a reference value, the printing process may continue to eject ink DL from the inkjet head PA (step S10), or may include controlling the concentration of particles PT in the ejected ink DL by feeding back the current concentration to the inkjet head PA (step S40).

[0119] The inkjet printing apparatus 10 can be used to perform an inkjet printing process in a process of forming a layer or pattern including particles PT on a printing target product (e.g., a target substrate). The inkjet printing apparatus 10 can jet ink DL in which particles PT are dispersed from an inkjet head PA onto the target substrate, and can perform a post-processing process on the ink DL disposed on the target substrate to form a layer or pattern including particles PT.

[0120] A method for printing ink according to one embodiment may include sensing or measuring the concentration of the PT particles included in the ink DL during a printing process that forms a layer or pattern comprising PT particles. As in the above embodiment, the inkjet printing apparatus 10, including the ink concentration measuring device 100, can sense the concentration of PT particles in the ink DL by measuring changes in droplets and PT particles ejected from the inkjet head PA, and can maintain a uniform concentration of PT particles in the ejected ink DL by feeding the concentration back to the inkjet head PA. Hereinafter, a method for printing ink using the inkjet printing apparatus 10 will be further described with reference to other accompanying drawings.

[0121] Figures 13 to 16 This is a schematic diagram illustrating a method for printing inks according to one embodiment. Figures 13 to 16 Sequential usage Figure 9 Methods for printing ink DL using inkjet printing equipment 10.

[0122] First, refer to Figure 13Ink DL is ejected from the inkjet printhead PA of the inkjet printing apparatus 10 (step S10). As described above, ink DL may include solvent SV and multiple particles PT dispersed in solvent SV. Although not shown in the figures, ink DL may be contained in an ink storage unit included in the inkjet printing apparatus 10 and then injected into the inkjet printhead PA through a conduit. Ink DL can be ejected through multiple nozzles included in the inkjet printhead PA and can be sprayed onto a target substrate (not shown) that is the printing target.

[0123] Ink DL can be ejected from the inkjet head PA in the first direction DR1. The ink DL can be ejected from the inkjet head PA, passed through the irradiation areas SA1 and SA2 irradiated by the light irradiation devices 110 (111 and 113) of the ink concentration measuring device 100, and sprayed onto the target substrate.

[0124] Next, refer to Figure 14 When ink DL ejected from the inkjet head PA passes through the first irradiation area SA1, the first light irradiation device 111 can irradiate the first irradiation area SA1 with the first light L1, and the first sensing device 131 can obtain data about the first emitted light SL1 scattered from the ink DL (step S20). In an embodiment where the ink density measuring device 100 of the inkjet printing apparatus 10 includes a reflector 190 facing the first light irradiation device 111, the ink DL is ejected to pass through the center of curvature of the reflector 190, and when the ink DL is located in the first irradiation area SA1, the first light irradiation device 111 can irradiate the first light L1.

[0125] In some embodiments, the center of curvature of the reflector 190 may overlap with the first illumination area SA1, and the first light L1 may be illuminated when the ink DL is placed at the center of curvature of the reflector 190. The first light L1 illuminated from the first light illumination device 111 may be scattered by the ink DL and may be guided toward the reflector 190 as a first outgoing light SL1. The reflector 190 may reflect the first outgoing light SL1, and the first sensing device 131 may sense the first outgoing light SL1 reflected from the reflector 190.

[0126] The data of the first emitted light SL1 sensed by the first sensing device 131 can be data related to the number of particles PT in the ink DL. When the number of particles PT in the ink DL is large, the intensity and scattering intensity of the first emitted light SL1 can be large, and when the number of particles PT in the ink DL is small, the intensity and scattering intensity of the first emitted light SL1 can be small.

[0127] Next, refer to Figure 15When ink DL ejected from the inkjet head PA passes through the second irradiation area SA2, the second light irradiation device 113 can irradiate the second irradiation area SA2 with second light L2, and the second sensing device 133 can obtain data about the second emitted light SL2 refracted from the ink DL (step S20). In an embodiment where the ink density measuring device 100 of the inkjet printing apparatus 10 is arranged such that the second light irradiation device 113 and the second sensing device 133 face each other, the second light L2 irradiating the second irradiation area SA2 can be refracted by the ink DL to be incident on the second sensing device 133 as the second emitted light SL2. The second sensing device 133 can sense the second emitted light SL2 to obtain data about the size, volume, and velocity of the ink DL.

[0128] Next, refer to Figure 16 The processor 150 of the ink concentration measuring device 100 can sense the concentration of particles PT in the ink DL based on the data of emitted light SL1 and SL2 acquired by the sensing device 130, and can determine whether the concentration of particles PT in the ink DL deviates from the reference value (step S30). The processor 150 can calculate the change in the number of particles PT in the ink DL based on the data of the first emitted light SL1 acquired by the first sensing device 131, calculate the size and volume of the ink DL ejected from the inkjet head PA based on the data of the second emitted light SL2 acquired by the second sensing device 133, and calculate the concentration of particles PT and the change in concentration based on the calculated values.

[0129] According to one embodiment, the change in particle PT concentration calculated by processor 150 can be calculated by comparing the data of emitted light SL1 and SL2 acquired by sensing device 130 with the data acquired in each printing process, and the particle PT concentration can be calculated by comparing it with a reference value stored in processor 150 before the printing process. In processor 150, when the particle PT concentration in ink DL is within the range required by the printing process, data of emitted light SL1 and SL2 that appear when the corresponding ink DL is irradiated with light L1 and L2 can be stored. As the printing process of ink DL proceeds, processor 150 can filter the emitted light SL1 and SL2 data acquired from sensing device 130 in the same format as the previously stored reference value data, and can determine whether the particle PT concentration in ink DL exceeds the error range of the reference value by mutual comparison (step S30).

[0130] Figure 17 and Figure 18 It is a graph showing emitted light data based on the concentration of particles in the ink measured using inkjet printing equipment.

[0131] Figure 17and Figure 18 This is a graph showing the normalized scattering intensity of the emitted light SL1 and SL2, based on the concentration of particles PT in the ink DL, when light L1 and L2 irradiated from the light irradiation device 110 are scattered or refracted by the ink DL and incident on the sensing device 130 as emitted light SL1 and SL2. Figure 17 In the chart, the "normalized scattering intensity" on the vertical axis is displayed by normalizing the scattering intensity of the first emitted light SL1 when the first emitted light L1, as a short-wavelength light, is irradiated. It can be seen that when the normalized scattering intensity of the first emitted light SL1 has a value close to "1.0", the light is scattered less by the ink DL, and when the normalized scattering intensity of the first emitted light SL1 indicates a value far from "1.0", the light is scattered more significantly by the ink DL.

[0132] Figure 18 Showing about Figure 17 Calculation of the standard deviation of the normalized scattering intensity of the first emitted light SL1. Figure 18 In the medium, a large standard deviation value can mean a large scattering intensity produced by the ink DL, and a small standard deviation value can mean a small scattering intensity produced by the ink DL.

[0133] refer to Figure 17 and Figure 18 It can be seen that as the concentration of particles PT in the ink DL increases, more light exhibiting a normalized scattering intensity of the first emitted light SL1 with a value far from "1.0" is detected. Conversely, it can be seen that as the concentration of particles PT in the ink DL decreases, more light exhibiting a normalized scattering intensity of the first emitted light SL1 with a value close to "1.0" is detected. Furthermore, it can be seen that as the concentration of particles PT in the ink DL decreases, the standard deviation of the normalized scattering intensity of the scattered light decreases, and as the concentration of particles PT in the ink DL increases, the standard deviation of the normalized scattering intensity of the scattered light increases.

[0134] The processor 150 included in the ink concentration measuring device 100 of the inkjet printing equipment 10 can store emitted light data based on the concentration of particles PT in the ink DL. For example, when the ink DL ejected from the inkjet printhead PA of the inkjet printing equipment 10 has a particle PT concentration of 4 wt%, a data value in which the particle PT concentration of the ink DL is 4 wt% can be used as a reference value. Figure 17 and Figure 18 The data shown is stored in processor 150.

[0135] The data of emitted light SL1 and SL2 acquired from the first sensing device 131 and the second sensing device 133 during the ink printing process can be used as... Figure 17 and Figure 18 The normalized scattering intensity and standard deviation of the scattered light shown are included in the processor 150. In the first sensing device 131, data regarding the number of particles PT is acquired as data for the first emitted light SL1 generated by short-wavelength light, which can be compensated for by data regarding the volume of the ink DL, which is data for the second emitted light SL2 generated by long-wavelength light at the second sensing device 133. When the volume and size of the ink DL are simply ignored and only reference data are compared with the data of the first emitted light SL1, the amount of variation based on the volume change per unit droplet of the ink DL is not considered, and therefore, errors may exist in determining the error range. Therefore, the processor 150 can synthesize filtered data acquired from each of the first and second sensing devices 131 to calculate the intensities of the emitted lights SL1 and SL2, as well as the standard deviation of the intensities.

[0136] Next, the processor 150 compares the values ​​calculated based on the emitted light data with stored reference values ​​to determine whether these values ​​exceed the error range. Here, the reference values ​​stored in the processor 150 can be values ​​set by the user using the inkjet printing equipment 10. However, this disclosure is not limited to this, and the reference values ​​can be set values ​​learned by the inkjet printing equipment 10 during repeated printing processes.

[0137] According to one embodiment, in addition to reference data on the concentration of particles PT in the ink DL, the processor 150 can further store data values ​​of the error range. The reference data that can be stored in the processor 150 may be, as emitted light data of the ink DL, a normalized scattering intensity of the scattered light (…). Figure 17 The data and the standard deviation of the normalized scattering intensity ( Figure 18 The processor 150 can store the error range based on each data point. The processor 150 can store the normalized scattering intensity and standard deviation values ​​of the emitted light SL1 and SL2 as one or more data points based on the concentration of particles PT in the ink DL. For example, in addition to the data for an ink DL concentration of 4 wt% serving as a reference value, the processor 150 can further store data for concentrations of 1 wt%, 2 wt%, 3 wt%, 5 wt%, and 6 wt%, etc., as data within the error range from the reference value and data outside the error range.

[0138] In addition to the case shown with reference to the accompanying drawings, a large amount of data values ​​can be stored in the processor 150. Therefore, by comparing data values ​​with different concentration ranges, the processor 150 can more accurately calculate the concentration of particles PT in the ink DL ejected in the process, compared to simply comparing the values ​​calculated during the printing process with reference values ​​within the error range.

[0139] When processor 150 determines that the calculated value exceeds the error range compared to the reference value when comparing it with stored reference values ​​and other data, processor 150 can control the concentration of particles PT in ink DL by feeding back the corresponding result to inkjet head PA (step S40). For example, when the value calculated by processor 150 based on the emitted light data indicates that the concentration of particles PT is lower than the reference value, processor 150 can provide feedback to inkjet head PA to increase the concentration of particles PT in ink DL. Conversely, when the value calculated by processor 150 based on the emitted light data indicates that the concentration of particles PT is higher than the reference value, processor 150 can provide feedback to inkjet head PA to decrease the concentration of particles PT in ink DL. Alternatively, when it is determined that the value calculated by processor 150 based on the emitted light data is within the error range compared to the reference value, the printing process can be repeated without adjusting the concentration of particles PT in ink DL.

[0140] The above-described process enables the execution of a method for printing ink using an inkjet printing apparatus 10. According to one embodiment, the inkjet printing apparatus 10 may include an ink concentration measuring device 100 for calculating and sensing the concentration change of particles PT in the ink DL in real time while performing the printing process. The inkjet printing apparatus 10 has the advantage of uniformly maintaining the quality of the product formed by the printing process by feeding back the real-time sensed change to the inkjet head PA.

[0141] In the above embodiments, the ink concentration measuring device 100 of the inkjet printing apparatus 10 may undergo a process of storing reference value data set by the user in the processor 150. However, this disclosure is not limited thereto, and the method of printing ink using the inkjet printing apparatus 10 may further include storing an initial value related to the concentration of particles PT in the ink DL in the processor 150 before printing the ink DL onto the target product.

[0142] Figure 19 This is a flowchart illustrating a method of printing ink using an inkjet printing apparatus according to another embodiment.

[0143] refer to Figure 19 The method of printing ink according to one embodiment may further include, as in... Figure 12In the embodiments, the step of storing initial value data in the processor 150 (step S0) is performed before steps S10 to S40 of printing ink DL on the target product. Step S0 of storing initial value data may include ejecting ink DL in which particles PT are dispersed from the inkjet head PA (step S1), irradiating the ejected ink DL with light L1 and L2 to obtain data of emitted light SL1 and SL2 (step S2), and setting an initial value for the concentration of particles PT in the ink DL (step S3). Although the figures show that step S0 of storing initial value data is performed once, the present disclosure is not limited thereto. Step S0 of storing initial value data may be performed at least once, and may be repeated several times depending on the product specifications of the inkjet printing equipment 10. Embodiments may include storing initial values ​​through a trial run of the inkjet printing equipment 10, instead of storing separate reference values ​​in the processor 150. Step S1 of ejecting ink DL in which particles PT are dispersed and step S2 of irradiating the ejected ink DL with light L1 and L2 to obtain data of emitted light SL1 and SL2 are the same as those mentioned above. Figures 12 to 18 The descriptions are essentially the same. Detailed descriptions will be omitted.

[0144] When ink DL containing dispersed particles PT is manufactured, initial values ​​stored in processor 150 can be set using inkjet printing equipment 10 without undergoing experiments to generate emitted light data from ink DL produced as individual samples. Therefore, it is advantageous that initial values ​​satisfying the specifications of the corresponding inkjet printing equipment 10 can be set, and for example… Figure 12 Storing separate reference data, as in the embodiments described, allows for more accurate sensing of particle PT concentration.

[0145] When it is determined that step S0 of storing the initial value data has been completed, the processor 150... Figure 12 In the embodiment, ink DL is sprayed onto the target product as described above, and for each printing process, the concentration of particles PT in the ink DL is determined to be within the error range of a stored initial value. Based on the result determined by the processor 150, the inkjet head PA can repeat the spraying of ink DL, or it can perform step S40 of controlling the concentration of particles PT in the ink DL injected into the inkjet head PA.

[0146] In the above embodiments, the inkjet head PA is exemplified as ejecting ink DL from a single nozzle, but this disclosure is not limited thereto. In another embodiment, the inkjet head PA can be configured to include multiple nozzles ( Figure 20The inkjet printing apparatus 10, according to one embodiment, can simultaneously eject multiple ink droplets (DL) from multiple nozzles (NZ) of the inkjet head PA. Some of the ink DL ejected from the multiple nozzles (NZ) of the inkjet head PA can be placed in the same area, and the ink DL ejected from multiple different nozzles (NZ) can form a layer or pattern within a predetermined area. The inkjet printing apparatus 10 can sense not only the number or concentration of particles (PT) per unit droplet of the ejected ink DL for each nozzle (NZ), but also the change in the total number of particles (PT) included in the multiple ink DLs ejected from the multiple nozzles (NZ) or the difference between the number of particles (PT) included in the ink DLs ejected from the nozzles (NZ).

[0147] Figure 20 This is a diagram illustrating the arrangement of multiple nozzles included in the inkjet head of an inkjet printing apparatus according to one embodiment. Figure 21 It shows from Figure 20 The diagram shows the ink ejection from multiple nozzles included in the inkjet head. Figure 20 This is a plan view of the inkjet head PA as viewed from a surface on which multiple nozzles NZ are provided.

[0148] refer to Figure 20 and Figure 21 The inkjet printing apparatus 10's inkjet head PA can have a shape extending in one direction and include a plurality of nozzles NZ arranged in one and another direction. The plurality of nozzles NZ can be disposed on a surface of the base portion of the inkjet head PA (e.g., on the bottom surface of the base portion). The plurality of nozzles NZ can have a shape that partially protrudes from the bottom surface of the inkjet head PA, but is not limited thereto. For example, the plurality of nozzles NZ can penetrate the bottom surface of the base portion of the inkjet head PA and connect to a conduit (not shown) disposed inside the inkjet head PA.

[0149] Multiple nozzles NZ can be arranged in one direction extending from the inkjet head PA and in another direction perpendicular to that direction. The multiple nozzles NZ can be arranged in one, two, or more rows in one direction. In an inkjet head PA, multiple inks DL can be ejected simultaneously from multiple nozzles NZ, and the inks DL ejected from different nozzles NZ can be respectively disposed in different regions JA1, JA2, JA3, ..., JAN formed on the target substrate SUB, which serves as the printing target.

[0150] For example, the multiple nozzles NZ disposed in the inkjet head PA can be divided into multiple nozzle groups NG1, NG2, NG3, ..., NGn, which respectively spray ink DL into multiple regions JA1, JA2, JA3, ..., JAN formed on the target substrate SUB. Each of the nozzle groups NG1, NG2, NG3, ..., NGn can be composed of one or more nozzles NZ, and the ink DL sprayed simultaneously from one or more nozzles NZ can be respectively placed together in predetermined regions JA1, JA2, JA3, ..., JAN of the target substrate SUB.

[0151] Multiple nozzles NZ belonging to the first nozzle group NG1 of the inkjet head PA can spray ink DL onto the first region JA1 of the target substrate SUB. Multiple nozzles NZ belonging to the second nozzle group NG2 can spray ink DL onto the second region JA2 of the target substrate SUB, and multiple nozzles NZ belonging to the third nozzle group NG3 and the nth nozzle group NGn can respectively spray ink DL onto the third region JA3 and the nth region JAN of the target substrate SUB. The multiple nozzles NZ can be divided into different nozzle groups NG1, NG2, NG3, ..., NGn according to the position of each of the nozzles NZ and the regions JA1, JA2, JA3, ..., JAN on the target substrate SUB in which the ink to be sprayed is placed. However, this disclosure is not limited to this, and each nozzle NZ can be divided into different nozzle groups NG1, NG2, NG3, ..., NGn according to the preset conditions in the inkjet head PA of the inkjet printing apparatus 10.

[0152] When multiple nozzles NZ simultaneously spray ink DL onto any region JA1, JA2, JA3, ..., JAN, the quality of the layer or pattern formed by placing the ink DL on the target substrate SUB can be achieved by uniformly maintaining the concentration of particles PT in the ink DL sprayed by each nozzle NZ, or by uniformly maintaining the total number of particles PT included in the multiple ink DLs simultaneously sprayed by multiple nozzles NZ belonging to each nozzle group NG1, NG2, NG3, ..., NGn. For example, the quality of the layer or pattern formed by the ink DL placed in the first region JA1 of the target substrate SUB can be achieved by uniformly maintaining the total number of particles PT included in the ink DL sprayed by the nozzles NZ belonging to the first nozzle group NG1. Although not shown in the figures, the ink concentration measuring device 100 and its operation can maintain multiple ink DLs sprayed from the inkjet head PA, similar to the embodiment described above, at a constant number or concentration of particles PT in the ink DL. According to one embodiment, in the inkjet printing apparatus 10, the ink concentration measuring device 100 can sense the concentration change of particles PT in all ink DL ejected from each nozzle group NG1, NG2, NG3, ... NGn, or the concentration change of particles PT in ink DL ejected from other nozzle groups NG1, NG2, NG3, ... NGn, and can feed back the change to the inkjet printing apparatus 10.

[0153] Figure 22 This is a flowchart illustrating the sequence of some steps in a method for printing ink according to one embodiment. Figure 22 Show in more detail Figure 12 and Figure 19 The step performed in step S30 of the method for determining whether the concentration of particles PT in the ink DL deviates from the reference value.

[0154] refer to Figure 22In a method for printing ink according to one embodiment, step S30, determining whether the concentration of particles PT in ink DL deviates from a reference value, may include classifying the emitted light data of ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn from multiple emitted light data (step S31), calculating the concentration of particles PT in each drop of ink DL based on the multiple emitted light data (step S32), calculating the sum of the number of particles PT in ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn (step S33), and determining whether the concentration of particles PT in ink DL exceeds an error range based on the sum of the data (step S34). This embodiment differs from the aforementioned embodiment in which the concentration of particles PT in each drop of ink DL is sensed in that the change in the number of particles PT in all ink DL ejected from nozzle groups NG1, NG2, NG3, ... NGn, which include multiple nozzles NZ, is sensed.

[0155] When ink DL is ejected from multiple nozzles NZ, the light irradiation device 110 and the sensing device 130 in the ink density measuring device 100 of the inkjet printing apparatus 10 can obtain emitted light data from each drop of ink DL. This is the same as described with reference to the embodiment above. When the light irradiation device 110 irradiates each drop of ink DL with light, the sensing device 130 can obtain data on the scattered or refracted light from the ink DL.

[0156] Then, the processor 150 of the ink concentration measuring device 100 classifies the multiple emitted light data of each drop of ink DL obtained by the sensing device 130 into emitted light data of ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn (step S31). For example, data on ink DL ejected from nozzles NZ belonging to the first nozzle group NG1 can be classified as emitted light data of the first nozzle group NG1, and data on ink DL ejected from nozzles NZ belonging to the second nozzle group NG2 can be classified as emitted light data of the second nozzle group NG2. Data on ink DL ejected from nozzles NZ belonging to different nozzle groups NG1, NG2, NG3, ... NGn can also be classified into emitted light data of different nozzle groups NG1, NG2, NG3, ... NGn respectively. Emitted light data classified as belonging to the same nozzle group, together with data on ink DL ejected from other nozzles NZ, can be considered as data on all ink DL ejected from nozzles NZ belonging to the corresponding nozzle groups NG1, NG2, NG3, ... NGn.

[0157] Next, the concentration of particle PT in the ink DL is calculated based on each of the multiple emitted light data (step S32), and the sum of the number of particle PT in the ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn is calculated based on the emitted light data (step S33). In this step, data on the particle concentration of all ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn is calculated, rather than data on the particle concentration of each individual ink DL ejected from each nozzle NZ. For example, the concentration or number of particle PT in all ink DL simultaneously ejected from the first nozzle group NG1 can be calculated by summing the particle PT concentrations of each drop of ink DL, except for the particle PT concentration of ink DL ejected from multiple nozzles NZ belonging to the first nozzle group NG1. A first sum of data can be calculated based on the ink DL ejected from the first nozzle group NG1, and a second sum of data can be calculated based on the ink DL ejected from the second nozzle group NG2. For each of the other nozzle groups NG3, ... NGn, similarly, the third to nth phase summation data can be calculated based on all simultaneously ejected ink DL. The nth phase summation data can be a reference for the concentration of particles PT in the ink DL.

[0158] As described above, the quality of the layer or pattern formed on the target substrate SUB by ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn ultimately depends on the concentration of PT particles in all ink DL ejected from nozzles NZ belonging to any one of the nozzle groups NG1, NG2, NG3, ... NGn, rather than on the concentration of PT particles in a single ink DL. Although the concentration of PT particles in the ink DL ejected for each nozzle NZ varies, when the concentration or number of PT particles in all ink DL ejected from nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn remains unchanged, the layer or pattern formed by ink DL ejected from nozzles NZ of the corresponding nozzle groups NG1, NG2, NG3, ... NGn can maintain a uniform quality.

[0159] According to one embodiment, the inkjet printing apparatus 10 can determine whether the concentration of particles PT in the ink DL exceeds the error range based on the summation of emitted light data of ink DL ejected from nozzles NZ of the same nozzle group NG1, NG2, NG3, ... NGn (step S34). Although the number or concentration of particles PT in the ink DL ejected from each nozzle NZ varies, the concentration of ink DL ejected from the same nozzle group NG1, NG2, NG3, ... NGn may not change due to variations in the number or concentration of particles PT generated from other nozzles NZ belonging to the same nozzle group NG1, NG2, NG3, ... NGn. In this case, the ink DL ejected in the corresponding printing process has ejected particles PT within the reference value range, and therefore, the same process can be repeated without controlling the number of particles PT in the ink DL.

[0160] Conversely, although the change in the number or concentration of particle PT generated in each drop of ink DL falls within the range of reference values, when the change in the number or concentration of particle PT in all ink DLs ejected from the same nozzle group NG1, NG2, NG3, ... NGn deviates from the reference values, the concentration of particle PT in the ink DLs can be controlled in the next process. According to one embodiment, in the ink concentration measuring device 100 of the inkjet printing apparatus 10, in addition to the reference value for the number or concentration of particle PT per unit droplet of each drop of ink DL, the processor 150 can further store reference values ​​for the number or concentration of particle PT in all ink DLs ejected from the same nozzle group NG1, NG2, NG3, ... NGn. In the printing process, in addition to the change in the concentration of particle PT in each ink DL ejected, the processor 150 can calculate the change in the concentration of particle PT in all ink DLs ejected from the same nozzle group NG1, NG2, NG3, ... NGn. Therefore, in the inkjet printing apparatus 10 according to one embodiment, when ink DL is jetted for each of the regions JA1, JA2, JA3, ..., JAN in the target substrate SUB on which the printing process is performed, the quality of the layer or pattern formed in each of the regions JA1, JA2, JA3, ..., JAN can be uniformly maintained by simultaneously jetting ink DL from multiple nozzles NZ.

[0161] On the other hand, a target substrate SUB comprising multiple regions JA1, JA2, JA3, ..., JAn may have layers or patterns having the same number of particles PT formed in each of regions JA1, JA2, JA3, ..., JAn through a single ink printing process, but this disclosure is not limited thereto. In another embodiment, for example, when ink DL ejected from a first nozzle group NG1 and a second nozzle group NG2 forms layers or patterns in the first region JA1 and the second region JA2 of the target substrate SUB, the layers formed in the first region JA1 and the layers formed in the second region JA2 may or may not include substantially the same number of particles PT. This may vary depending on the design conditions of the layers or patterns formed on the target substrate SUB. When the same layer or pattern is to be formed in a printing process regardless of the position of each of regions JA1, JA2, JA3, ..., JAn, the number or concentration of particles PT in the ink DL ejected from different nozzle groups NG1, NG2, NG3, ..., NGn should be kept consistent with each other. Conversely, when different layers or patterns are to be formed in a printing process according to the position of each of the regions JA1, JA2, JA3, ..., JAN, the number or concentration of particles PT in the ink DL ejected from different nozzle groups NG1, NG2, NG3, ..., NGn should be kept consistent.

[0162] In a method for printing ink according to one embodiment, the method for determining whether the concentration of particles PT in the ink DL exceeds the error range (step S34) may vary depending on the design value of the layer or pattern formed on the target substrate SUB on which the ink printing process is performed.

[0163] Figure 23 It is shown Figure 22 A flowchart showing the sequence of steps. Figure 23 Show in more detail Figure 22 Step S34 is used to determine whether the concentration of particles PT in ink DL exceeds the error range based on the summation data.

[0164] Combination Figure 22 refer to Figure 23In an embodiment where, in a single printing process, regardless of the position of each of regions JA1, JA2, JA3, ..., JAN, the same layer or pattern is formed on the target substrate SUB on which the ink printing process is performed, step S34, which determines whether the concentration of particles PT in the ink DL exceeds the error range, may include determining whether the number of particles PT in the ink DL ejected from nozzle NZ of different nozzle groups NG1, NG2, NG3, ..., NGn is equal to each other (step S341) and determining whether the number of particles PT in the ink DL ejected from nozzle NZ of any nozzle group NG1, NG2, NG3, ..., NGn exceeds the error range of a reference value (step S342).

[0165] Before determining whether the ink DL ejected from each of the multiple nozzle groups NG1, NG2, NG3, ... NGn exceeds the error range of the reference value, it can be determined whether the ink DL ejected from different nozzle groups NG1, NG2, NG3, ... NGn has different data values ​​by comparing the data on ink DL ejected from different nozzle groups NG1, NG2, NG3, ... NGn with each other. Since the same layer or pattern should be formed in a printing process regardless of the position of each of the regions JA1, JA2, JA3, ... JAn, it is expected that the number or concentration of particles PT in the ink DL will be the same, even though the ink DL is ejected from different nozzle groups NG1, NG2, NG3, ... NGn.

[0166] For example, the first, second, and third summation data of ink DL ejected from the first nozzle group NG1, the second nozzle group NG2, and the third nozzle group NG3 are compared with each other, so that nozzle groups NG1, NG2, NG3, ... NGn with different summation data can be selected. When the first nozzle group NG1 has a data value that is different from the data values ​​of the second nozzle group NG2 and the third nozzle group NG3, in a subsequent step, it is determined whether the number of particles PT in the ink DL ejected from the nozzle NZ of the first nozzle group NG1 exceeds the error range of the reference value (step S342). When the first summation data of the ink DL ejected from the first nozzle group NG1 exceeds the error range of the reference value, the concentration or number of particles PT in the ink DL ejected from the nozzle of the first nozzle group NG1 is controlled (step S40). On the other hand, when the first summation data of the ink DL ejected from the first nozzle group NG1 does not exceed the error range of the reference value, the concentration or quantity of particles PT in the ink DL ejected from the nozzles of the nozzle groups NG2, NG3, ... NGn, which have summation data values ​​different from those of the first nozzle group NG1, is controlled (step S40).

[0167] Although the summed data of the ink DL ejected from the first nozzle group NG1, the second nozzle group NG2, and the third nozzle group NG3 are compared with each other and they are substantially equal or have data values ​​within the error range, in a subsequent step, it is determined whether the number of particles PT in the ink DL ejected from nozzle NZ of any of the nozzle groups NG1, NG2, NG3, ... NGn exceeds the error range of the reference value (step S342). When the data of the ink DL ejected from the first nozzle group NG1 does not exceed the error range of the reference value, the printing process is repeated without controlling the number of particles PT in the ink DL, and when the data exceeds the error range of the reference value, the number of particles PT in the ink DL of all the multiple nozzle groups NG1, NG2, NG3, ... NGn can be controlled (step S40) and the printing process can be performed. In this case, in the ink density measuring device 100 of the inkjet printing equipment 10, the processor 150 can store the reference values ​​of the multiple nozzle groups NG1, NG2, NG3, ... NGn as the same value. Since different nozzle groups NG1, NG2, NG3, ... NGn should spray the same number of particles PT, the reference values ​​stored in the processor 150 can be applied equally, regardless of the nozzle group NG1, NG2, NG3, ... NGn.

[0168] On the other hand, in an embodiment where, in a single printing process, different layers or patterns are formed on a target substrate SUB on which the ink printing process is performed, according to the positions of regions JA1, JA2, JA3, ..., JAN, the step S34 of determining whether the concentration of particles PT in the ink DL exceeds the error range may include determining whether the number of particles PT in the ink DL ejected from the nozzle NZ of each nozzle group NG1, NG2, NG3, ..., NGn exceeds the error range of different reference values ​​(step S343).

[0169] Since different layers or patterns should be formed according to the positions of regions JA1, JA2, JA3, ..., JAn in a printing process, when ink DL is ejected from different nozzle groups NG1, NG2, NG3, ..., NGn, it is desirable to control the number or concentration of particles PT in each drop of ink DL according to different preset reference values.

[0170] Figure 24 It is shown Figure 23 A diagram of one step.

[0171] Combination Figure 22 and Figure 23 refer to Figure 24The inks DL (DL1, DL2, and DL3) sprayed onto different regions JA1, JA2, JA3, ..., JAn of the target substrate SUB can have different numbers of particles PT. For example, in the first region JA1, nozzle NZ of the first nozzle group NG1 can spray the first ink DL1, and in the second region JA2, nozzle NZ of the second nozzle group NG2 can spray the second ink DL2. As described above, in the third region JA3 and the nth region JAn, nozzle NZ of the third nozzle group NG3 and the nth nozzle group NGn can respectively spray the third ink DL3 and other inks DL. Each of the first ink DL1, the second ink DL2, and the third ink DL3 can be set to include a different number or concentration of particles PT per unit droplet. In addition, the number or concentration of particles PT can be different in all the inks DL sprayed from different nozzle groups NG1, NG2, NG3, ..., NGn.

[0172] When calculating the sum of the ink DL ejected from the first nozzle group NG1, the second nozzle group NG2, and the third nozzle group NG3, each sum of data is compared with a different reference value to determine whether the sum of data exceeds the error range (step S343). For the first ink DL1 ejected from the first nozzle group NG1, the sum of data is determined to exceed the error range based on the first reference value, and for the second ink DL2 ejected from the second nozzle group NG2, the sum of data is determined to exceed the error range based on the second reference value. Even in the case of other nozzle groups NG3, ... NGn, the error range of each nozzle group is determined based on a different reference value. The result of comparing the data of each nozzle group NG1, NG2, NG3, ... NGn with the reference value is that when the ink DL of some nozzle groups NG1, NG2, NG3, ... NGn exceeds the error range, the number of particles PT in the ink DL ejected from the corresponding nozzle groups NG1, NG2, NG3, ... NGn can be controlled (step S40).

[0173] In this case, in the ink density measuring device 100 of the inkjet printing equipment 10, the processor 150 can store different reference values ​​for multiple nozzle groups NG1, NG2, NG3, ... NGn, or at least some of these different reference values. When a layer or pattern comprising a different number of particles PT is formed in each of the multiple regions JA1, JA2, JA3, ... JAn of the target substrate SUB, the number of reference values ​​stored in the processor 150 can be the same as the number of different regions JA1, JA2, JA3, ... JAn of the target substrate SUB. On the other hand, when a layer or pattern comprising the same number of particles PT is formed in some regions of the multiple regions JA1, JA2, JA3, ... JAn of the target substrate SUB, the number of reference values ​​stored in the processor 150 can be different from the number of different regions JA1, JA2, JA3, ... JAn of the target substrate SUB.

[0174] In an inkjet printing apparatus 10 according to one embodiment, the inkjet head PA includes multiple nozzles NZ that can be classified into multiple nozzle groups NG1, NG2, NG3, ... NGn. Therefore, the ink concentration measuring device 100 can sense changes in the quantity or concentration of particles PT in the ink DL in units of multiple nozzle groups NG1, NG2, NG3, ... NGn.

[0175] According to one embodiment, the inkjet printing apparatus 10 can be used to manufacture display devices comprising different layers or patterns for each of regions JA1, JA2, JA3, ..., JAN. Figure 29 The display device 1000 (referred to as "1000" in the original text) may include multiple regions JA1, JA2, JA3, ..., JAN, and different layers or patterns may be formed in each of the regions JA1, JA2, JA3, ..., JAN, or the same layer or pattern may be formed in some regions of the multiple regions JA1, JA2, JA3, ..., JAN, and different layers or patterns may be formed in at least some regions of the multiple regions JA1, JA2, JA3, ..., JAN. Hereinafter, a method for manufacturing the display device 1000 using inkjet printing equipment 10 will be described with reference to other accompanying drawings.

[0176] Figure 25 This is a flowchart illustrating a method for manufacturing a display device according to one embodiment. Figures 26 to 29 This is a cross-sectional view illustrating a method for manufacturing a display device using printing ink according to one embodiment. Figures 26 to 29 This is a view showing in sequence the process of forming a plurality of ink patterns JL1, JL2, JL3, ... JLn in a method of manufacturing a display device 1000 according to one embodiment.

[0177] refer to Figures 25 to 29 A method for manufacturing a display device 1000 according to one embodiment may include preparing a target substrate SUB (step S101), spraying ink DL from an inkjet head PA onto each of different regions JA1, JA2, JA3, ..., JAN of the target substrate SUB (step S102), obtaining data of emitted light SL1 and SL2 by irradiating the sprayed ink DL with light L1 and L2 (step S103), and determining whether the concentration of particles PT in the ink DL deviates from a reference value (step S104). In the ink concentration measuring device 100, the processor 150 senses the concentration change of particles PT in the ink DL, and based on whether the sensed value deviates from the reference value, the printing process may continue to spray ink DL from the inkjet head PA (step S102), or may include controlling the concentration of particles PT in the ink DL to be sprayed by feeding back the concentration change to the inkjet head PA (step S105). In the method for manufacturing the display device 1000, the steps of jetting ink DL (step S102), obtaining emitted light data (step S103), and determining whether the data exceeds the error range of a reference value (step S104) are the same as those described above. Figures 12 to 16 The description is basically the same. Furthermore, the display device 1000 is manufactured by performing an ink printing process on a target substrate SUB comprising multiple regions JA1, JA2, JA3, ..., JAn, as described above. Figures 21 to 24 The descriptions are essentially the same. The following text will simplify the descriptions of the repeated content and focus primarily on the differences.

[0178] First, such as Figure 26 As shown, a target substrate SUB is prepared by performing an ink printing process thereon and includes multiple regions JA1, JA2, JA3, ..., JAn (step S101). The display device 1000 may include the target substrate SUB and the components formed on the target substrate SUB. Figure 29 Multiple ink patterns JL1, JL2, JL3, ... JLn. In embodiments, the display device 1000 manufactured using inkjet printing equipment 10 can refer to any electronic device capable of displaying moving or still images. Examples of the display device 1000 may include televisions, laptops, monitors, billboards, Internet of Things devices, mobile phones, smartphones, tablet PCs (“PCs”), electronic watches, smartwatches, watch phones, head-mounted displays, mobile communication terminals, electronic notebooks, e-books, portable multimedia players (“PMPs”), navigation devices, game consoles, digital cameras, and camcorders, etc.

[0179] The display device 1000 includes a display panel that provides a display screen. Examples of display panels may include inorganic light-emitting diode (LED) display panels, organic light-emitting diode (OLED) display panels, quantum dot (QD) light-emitting diode (OLED) display panels, plasma display panels, and field emission display panels. In the following description, an example of using an OLED display panel will be given, but this disclosure is not limited thereto, and other display panels may be applied within the same technical spirit.

[0180] The target substrate SUB may include a substrate portion 1001, a display layer 1003 disposed on the substrate portion 1001, and an insulating layer 1004 disposed on the display layer 1003. The target substrate SUB may include a plurality of regions JA1, JA2, JA3, ..., JAn defined on the insulating layer 1004, and is formed by a printing process using inkjet printing equipment 10.

[0181] Referring to the structure of the target substrate SUB, the substrate portion 1001 may include a substrate made of a transparent material and a circuit layer disposed on the substrate. The substrate may be made of an insulating material such as glass, quartz, or polymer resin. Additionally, the substrate may be a rigid substrate, but it may also be a flexible substrate that can be bent, folded, or rolled.

[0182] The circuit layer disposed on the substrate may include multiple switching elements. Each of the switching elements may be a thin-film transistor comprising polysilicon or a thin-film transistor comprising oxide semiconductor. Although not shown in the figures, multiple signal lines (e.g., gate lines, data lines, or power lines, etc.) for transmitting signals to each of the switching elements may be further disposed on the target substrate SUB.

[0183] Display layer 1003 may be disposed on substrate portion 1001 and include a plurality of light-emitting elements electrically connected to a circuit layer. In embodiments, display layer 1003 may include a plurality of electrodes and an organic light-emitting layer disposed between the plurality of electrodes, and display device 1000 may be an organic light-emitting display (OLED) device including organic materials as light-emitting materials. Each of the plurality of electrodes may be electrically connected to the circuit layer of substrate portion 1001, and the organic light-emitting layer may receive electrical signals from the electrodes to emit light. However, this disclosure is not limited thereto. In embodiments in which display device 1000 is not an organic light-emitting display device, display layer may include light-emitting layers or light-emitting elements other than organic light-emitting layers. In addition, although not shown in detail in the drawings, target substrate SUB may further include a plurality of layers or patterns disposed on substrate portion 1001 and display layer 1003.

[0184] The insulating layer 1004 may be disposed on the display layer 1003. The insulating layer 1004 may be disposed directly on the display layer 1003 to completely cover the display layer 1003. However, this disclosure is not limited thereto, and other layers may be further disposed between the insulating layer 1004 and the display layer 1003.

[0185] In one embodiment, the insulating layer 1004 may be composed of multiple layers, and each layer of the insulating layer 1004 may include an inorganic insulating material or an organic insulating material. For example, the inorganic insulating material may include silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, and silicon oxynitride (SiO2). x N y At least one of acrylic resin, methacrylic resin, polyisoprene, vinyl resin, epoxy resin, polyurethane resin, cellulose resin, and perylene resin. However, the structure and materials of the insulating layer 1004 are not limited to those described above, and various modifications can be made to the stacked structure or materials.

[0186] The target substrate SUB may include multiple regions JA1, JA2, JA3, ..., JAN defined on the insulating layer 1004, and multiple ink patterns JL1, JL2, JL3, ..., JLn may be formed in the regions JA1, JA2, JA3, ..., JAN, respectively, according to the printing process using the inkjet printing equipment 10. The ink patterns JL1, JL2, JL3, ..., JLn formed in the regions JA1, JA2, JA3, ..., JAN may be identical regardless of their position, or they may differ depending on their position. In embodiments where the ink patterns JL1, JL2, JL3, ..., JLn are identical regardless of their position, the method for manufacturing the display device 1000 can be... Figure 23 Steps S341 and S342 in the embodiments are performed. Alternatively, in the same embodiment where the ink patterns JL1, JL2, JL3, ... JLn differ according to their positions, the method of manufacturing the display device 1000 can be performed by... Figure 23 Step S343 in the embodiment is performed. In the following figures, a method for manufacturing the display device 1000 will be illustrated and described by... Figure 23 The steps S341 and S342 in the embodiment are executed.

[0187] refer to Figure 27 and Figure 28The inkjet head PA sprays ink DL onto each of different regions JA1, JA2, JA3, ..., JAN of the target substrate SUB (step S102), and obtains data of the emitted light SL1 and SL2 by irradiating the sprayed ink DL with light L1 and L2 (step S103).

[0188] The first nozzle group NG1 can spray ink DL into the first region JA1, the second nozzle group NG2 can spray ink DL into the second region JA2, and the third nozzle group NG3 can spray ink DL into the third region JA3. In embodiments where the same ink pattern JL1, JL2, JL3, ... JLn is formed in each of the plurality of regions JA1, JA2, JA3, ... JAN on the target substrate SUB, ink DL with the same concentration of particles PT can be sprayed from each of the first nozzle group NG1, the second nozzle group NG2, the third nozzle group NG3, ... the nth nozzle group NGn. However, alternatively, in embodiments where different ink patterns JL1, JL2, JL3, ... JLn are formed in the plurality of regions JA1, JA2, JA3, ... JAN on the target substrate SUB, ink DL with different concentrations of particles PT can be sprayed from each of the first nozzle group NG1, the second nozzle group NG2, the third nozzle group NG3, ... the nth nozzle group NGn.

[0189] Ink DL can be ejected from the inkjet head PA in the first direction DR1. The ink DL can be ejected from the inkjet head PA, passing through irradiation areas SA1 and SA2 irradiated by the light irradiation devices 110 (111 and 113) of the ink density measuring device 100, and sprayed onto the target substrate SUB. When the ink DL ejected from the inkjet head PA passes through the first irradiation area SA1, the first light irradiation device 111 can irradiate the first irradiation area SA1 with first light L1, and the first sensing device 131 can obtain data regarding the first emitted light SL1 scattered from the ink DL. When the ink DL ejected from the inkjet head PA passes through the second irradiation area SA2, the second light irradiation device 113 can irradiate the second irradiation area SA2 with second light L2, and the second sensing device 133 can obtain data regarding the second emitted light SL2 refracted from the ink DL. The description is the same as above.

[0190] The processor 150 of the ink concentration measuring device 100 can sense the concentration change of particles PT in the ink DL based on the data of emitted light SL1 and SL2 acquired by the sensing device 130, and can determine whether the concentration of particles PT in the ink DL deviates from the reference value (step S104). In an embodiment where the same ink pattern JL1, JL2, JL3, ... JLn is formed in each of multiple regions JA1, JA2, JA3, ... JAn, in this step, the following can be performed: Figure 23 Steps S341 and S342 in the above. In an embodiment where different ink patterns JL1, JL2, JL3, ... JLn are formed in multiple regions JA1, JA2, JA3, ... JLn respectively, in this step, the following can be performed: Figure 23 Step S343. Its detailed description is the same as above and will therefore be omitted. Based on the data obtained from the ink DL ejected from each of the nozzle groups NG1, NG2, NG3, ... NGn, when it is necessary to control the concentration of particles PT in the ink DL, the concentration is controlled (step S105); otherwise, the printing process is repeated.

[0191] Then, refer to Figure 29 The display device 1000 can be manufactured by forming multiple ink patterns JL1, JL2, JL3, ... JLn on the target substrate SUB through the above process.

[0192] Figure 30 This is a cross-sectional view showing a portion of a display device according to one embodiment.

[0193] Combination Figure 29 refer to Figure 30 According to one embodiment, a display device 1000 may include a target substrate SUB, and a plurality of wavelength conversion layers WLC1 and WLC2 and a light-transmitting layer LTU disposed on the target substrate SUB and formed using inkjet printing equipment 10. Additionally, the display device 1000 may further include a dam layer BK that divides regions JA1, JA2, JA3, ..., JAn in which each of the wavelength conversion layers WLC1 and WLC2 and the light-transmitting layer LTU is formed, and a capping layer CAP that covers the dam layer BK, the wavelength conversion layers WLC1 and WLC2, and the light-transmitting layer LTU.

[0194] A dam layer BK may surround a portion in which wavelength conversion layers WLC1 and WLC2 and a light-transmitting layer LTU are disposed on a target substrate SUB. The dam layer BK may be configured to have a predetermined height on the target substrate SUB. In embodiments, the dam layer BK may comprise an organic insulating material and may have a height ranging from 4 micrometers (μm) to 20 μm and a width ranging from 4 μm to 20 μm. However, this disclosure is not limited thereto. The figures illustrate a case where the side surfaces of the dam layer BK are perpendicular to the top surface of the target substrate SUB, but this disclosure is not limited thereto. In some embodiments, the side surfaces of the dam layer BK may be inclined or curved. In one example, the dam layer BK may have an inverted conical shape in which the width of the top surface is greater than the width of the bottom surface.

[0195] Wavelength conversion layers WLC1 and WLC2 and light-transmitting layer LTU can be disposed in the region surrounded by the embankment layer BK. Wavelength conversion layers WLC1 and WLC2 and light-transmitting layer LTU can be formed into an island pattern on the target substrate SUB. However, this disclosure is not limited thereto, and each of wavelength conversion layers WLC1 and WLC2 and light-transmitting layer LTU can be configured to extend in one direction to form a linear pattern.

[0196] Wavelength conversion layers WLC1 and WLC2 may include a first wavelength conversion layer WLC1 disposed in a first region JA1 and a second wavelength conversion layer WLC2 disposed in a second region JA2. A light-transmitting layer LTU may be disposed in a third region JA3. The accompanying drawings show portions in which each of the first wavelength conversion layer WLC1, the second wavelength conversion layer WLC2, and the light-transmitting layer LTU is disposed sequentially, but this disclosure is not limited thereto. The display device 1000 may include each of the first wavelength conversion layer WLC1, the second wavelength conversion layer WLC2, and the light-transmitting layer LTU provided as a plurality.

[0197] The first wavelength conversion layer WLC1 may include a first substrate resin BS1 and a first wavelength conversion material WLS1 provided in the first substrate resin BS1. The second wavelength conversion layer WLC2 may include a second substrate resin BS2 and a second wavelength conversion material WLS2 provided in the second substrate resin BS2. The first wavelength conversion layer WLC1 and the second wavelength conversion layer WLC2 may further include a first scatterer SCT1 and a second scatterer SCT2 dispersed in the substrate resin, respectively.

[0198] The light-transmitting layer LTU may include a third substrate resin BS3 and a third scatterer SCT3 contained in the third substrate resin BS3. The light-transmitting layer LTU transmits blue light while maintaining the wavelength of the third color blue light incident from the light-emitting element. The third scatterer SCT3 of the light-transmitting layer LTU can be used to adjust the emission path of the light emitted through the light-transmitting layer LTU. The light-transmitting layer LTU may not include a wavelength conversion material.

[0199] The first to third scatterers SCT1, SCT2, and SCT3 can be metal oxide particles or organic particles. Their description is the same as above. The first to third base resins BS1, BS2, and BS3 can include light-transmitting organic materials. For example, the first to third base resins BS1, BS2, and BS3 can include epoxy resin, acrylic resin, cardo resin, or imide resin, etc. The first to third base resins BS1, BS2, and BS3 can be formed from the same material, but this disclosure is not limited thereto.

[0200] The first wavelength conversion material WLS1 can convert blue light into red light, and the second wavelength conversion material WLS2 can convert blue light into green light. The first wavelength conversion material WLS1 and the second wavelength conversion material WLS2 can be quantum dots, quantum rods, or phosphors, etc. Examples of quantum dots can include group IV nanocrystals, group II-VI compound nanocrystals, group III-V compound nanocrystals, group IV-VI compound nanocrystals, and combinations thereof.

[0201] The capping layer (CAP) can be disposed on the wavelength conversion layers WLC1 and WLC2, the light transmission layer LTU, and the barrier layer BK. The CAP prevents impurities such as moisture or air from penetrating from the outside and damaging or contaminating the wavelength conversion layers WLC1 and WLC2 and the light transmission layer LTU. The CAP can be formed of an inorganic insulating material.

[0202] In the manufacturing process of the display device 1000, each of the different wavelength conversion layers WLC1 and WLC2 and the light-transmitting layer LTU may include different materials. Furthermore, although each of the different wavelength conversion layers WLC1 and WLC2 and the light-transmitting layer LTU includes the same scatterers SCT1, SCT2, and SCT3, the concentrations of the scatterers SCT1, SCT2, and SCT3 included in each layer may differ from each other. For example, the concentration of the first scatterer SCT1 in the first wavelength conversion layer WLC1 may differ from the concentration of the second scatterer SCT2 in the second wavelength conversion layer WLC2, and these concentrations may differ from the concentration of the third scatterer SCT3 in the light-transmitting layer LTU.

[0203] In one embodiment, in a method of manufacturing a display device 1000 using inkjet printing equipment 10, each of the different wavelength conversion layers WLC1 and WLC2 and the light-transmitting layer LTU can be formed individually by a printing process. In this case, in a first printing process, a plurality of first wavelength conversion layers WLC1 disposed on a target substrate SUB can be formed, and in a second printing process and a third printing process, a second wavelength conversion layer WLC2 and a light-transmitting layer LTU can be formed respectively. In this embodiment, since each of the inks DL ejected from the different nozzle groups NG1, NG2, NG3, ... NGn of the inkjet head PA forms the same wavelength conversion layers WLC1 and WLC2 and the light-transmitting layer LTU, it is possible to perform... Figure 23 Steps S341 and S342. In the first printing process, reference values ​​for the plurality of first wavelength conversion layers WLC1 for forming the display device 1000 can be set in the inkjet printing equipment 10, and the printing process can be performed. In the first printing process, since each of the different nozzle groups NG1, NG2, NG3, ... NGn ejects ink DL to form the first wavelength conversion layer WLC1, the concentration of particles PT in the ink DL ejected from the nozzle groups NG1, NG2, NG3, ... NGn can be kept substantially consistent with each other.

[0204] Then, when performing each of the second and third printing processes, reference values ​​for the plurality of second wavelength conversion layers WLC2 and the plurality of light-transmitting layers LTU used to form the display device 1000 can be set, and the printing process can be performed. The reference values ​​set in each of the second and third printing processes can be different, but can be applied in the same way to the plurality of nozzle groups NG1, NG2, NG3, ... NGn.

[0205] However, this disclosure is not limited thereto. In some embodiments, in the first printing process, the inkjet printing apparatus 10 can perform a process for simultaneously forming multiple first wavelength conversion layers WLC1, multiple second wavelength conversion layers WLC2, and multiple light-transmitting layers LTU. In embodiments, since the ink DL ejected from different nozzle groups NG1, NG2, NG3, ... NGn of the inkjet head PA forms different wavelength conversion layers WLC1 and WLC2 and light-transmitting layers LTU, it is possible to perform... Figure 23Step S343. In the printing process, the inkjet printing head PA of the inkjet printing equipment 10 can be set with reference values ​​for forming different wavelength conversion layers WLC1 and WLC2 and light-transmitting layer LTU of the display device 1000 at different nozzle groups NG1, NG2, NG3, ... NGn, and the printing process can be performed. For example, a first ink DL1 for forming the first wavelength conversion layer WLC1 in the first region JA1 can be ejected from the first nozzle group NG1, a second ink DL2 for forming the second wavelength conversion layer WLC2 in the second region JA2 can be ejected from the second nozzle group NG2, and a third ink DL3 for forming the light-transmitting layer LTU in the third region JA3 can be ejected from the third nozzle group NG3. The concentration of particles PT in the inks DL ejected from the nozzle groups NG1, NG2, NG3, ... NGn can have different values ​​and can be kept consistent individually.

[0206] In the above embodiments, the concentration of PT particles in the ink DL introduced into the inkjet head PA has been adjusted when the concentration of PT particles in the ink DL is changed during the ink DL printing process. However, as described above, the ink patterns JL1, JL2, JL3, ... JLn ultimately formed on the target substrate SUB can vary depending on the number of PT particles in all the ink DL particles in each of the regions JA1, JA2, JA3, ... JAn sprayed onto the target substrate SUB. According to one embodiment, in a method of manufacturing a display device 1000 using inkjet printing equipment 10, when the concentration of PT particles in the ink DL sprayed from any nozzle NZ is low, ink DL can be sprayed from another nozzle NZ onto the corresponding region to compensate for this. That is, in a method of manufacturing a display device 1000 according to one embodiment, different ink DLs can be sprayed as ink DLs with different concentrations of PT particles onto a region of the target substrate SUB.

[0207] Figure 31 This is a flowchart illustrating a method for manufacturing a display device according to another embodiment. Figure 32 and Figure 33 It is shown Figure 31 A cross-sectional view of one step in a method for manufacturing a display device.

[0208] refer to Figures 31 to 33A method for manufacturing a display device 1000 according to one embodiment may include preparing a target substrate SUB comprising different regions JA1, JA2, JA3, ..., JAn (step S101), spraying ink from a first nozzle NZ1 onto a region of the target substrate SUB (step S102), obtaining data of emitted light SL1 and SL2 by irradiating the sprayed ink DL with light L1 and L2 (step S103), determining whether the concentration of particles PT in the ink DL deviates from a reference value (step S104), and spraying ink DL from a second nozzle NZ2 onto the corresponding region (step S105). This embodiment is similar to... Figure 25 The difference between this embodiment and the previous one lies in the fact that step S105 is substantially different. In the following description, redundant details will be omitted, and the differences will be the focus.

[0209] When the first ink DL1 is ejected from the first nozzle NZ1 into the first region JA1, the emitted light data is obtained by irradiating the first light L1 and the second light L2 to calculate the particle concentration PT of the ink DL. The description of this step is the same as above.

[0210] Next, when it is determined, based on the acquired emitted light data, that the concentration of particles PT in the ink DL ejected into the first region JA1 deviates from a reference value, a second ink DL2 is ejected into the first region JA1 through a second nozzle NZ2, which is different from the first nozzle NZ1. In the first region JA1, the first ink DL1 ejected from the first nozzle NZ1 and the second ink DL2 ejected from the second nozzle NZ2 can be mixed. When the concentration of particles PT in the first ink DL1 deviates from the reference value, the ink concentration measuring device 100 of the inkjet printing apparatus 10 can sense the deviation, which can be compensated by the second nozzle NZ2, which is different from the first nozzle NZ1. The second nozzle NZ2 can eject the second ink DL2 into the first region JA1, where the first ink DL1 has already been ejected.

[0211] Although not shown in the accompanying drawings, when the first ink DL1 is ejected from the first nozzle NZ1 into the first region JA1, the second nozzle NZ2 can eject the second ink DL2 into a second region JA2, in addition to the first region JA1. When the second ink DL2 is ejected, the emitted light data of the second ink DL2 can be acquired by irradiating the first light L1 and the second light L2 in the same manner as the first ink DL1. When the emitted light data of the first ink DL1 indicates that the concentration of particles PT of the first ink DL1 is low, the ink concentration measuring device 100 can locate the nozzle NZ that ejects ink DL with a concentration of additional desired particles PT in the first region JA1. When the second ink DL2 has a concentration of particles PT that is as much as the insufficient concentration of the first ink DL1 ejected from the first nozzle NZ1, the second nozzle NZ2 can be used to further eject ink into the first region JA1 after the first ink DL1 is ejected. In different processes, first ink DL1 and second ink DL2 are sprayed, but they can be sprayed into the same area (e.g., first area JA1) to form an ink pattern JL1, JL2, JL3, ... JLn. By sensing the concentration of particles PT in the ink DL sprayed into the predetermined area in real time, the inkjet printing equipment 10 can not only control the concentration of particles PT in the ink DL sprayed through nozzle NZ, but also adjust or compensate the concentration of particles PT in the ink DL sprayed into the corresponding areas JA1, JA2, JA3, ... JAn through other adjacent nozzles NZ.

[0212] In concluding this detailed description, those skilled in the art will understand that many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the invention. Therefore, the preferred embodiments disclosed herein are used only in a general and descriptive sense, and not for purposes of limitation.

Claims

1. A method for printing ink, comprising: Ink containing multiple dispersed particles is ejected from the inkjet head; The sprayed ink is irradiated with a first light and a second light of different wavelengths to obtain data about the first and second emitted light emitted from the ink; The concentration of the particles in the ink is calculated based on the data regarding the first emitted light and the second emitted light; and Determine whether the concentration exceeds the error range of the reference value. Wherein, the first light has a wavelength of 500 nm or less, and the second light has a wavelength of 1000 nm or greater, and The calculation of the concentration of the particles includes: Based on the data regarding the first emitted light, obtain data regarding the number of particles in the ink; and Data regarding the volume of the ink is obtained based on the data regarding the second emitted light.

2. The method according to claim 1, wherein, The first emitted light is obtained by scattering the first light irradiated onto the ink, and The second emitted light is obtained by refracting the second light that is irradiated onto the ink.

3. The method according to claim 2, further comprising: The concentration change of the particles in the ink is calculated based on the data regarding the first emitted light and the second emitted light.

4. The method of claim 2, further comprising: Based on the error range determined that the concentration exceeds the reference value, the concentration of the particles in the ink injected into the inkjet head is controlled.

5. The method of claim 1, further comprising: The reference value is set before the ink is ejected from the inkjet head.

6. The method according to claim 5, wherein, The reference values ​​include the normalized scattering intensity of the light emitted from the ink and the standard deviation of the normalized scattering intensity when the first light and the second light are irradiated onto inks with different particle concentrations. The acquisition of the data regarding the first emitted light and the second emitted light includes acquiring the normalized scattering intensity of the first emitted light and the second emitted light and the standard deviation value of the normalized scattering intensity, and The calculation of the concentration of the particles in the ink includes comparing the normalized scattering intensity and the standard deviation value of the reference value with the data regarding the first emitted light and the second emitted light.

7. The method according to claim 1, wherein, The ink is ejected from the inkjet head in a first direction. The first light is irradiated in a second direction perpendicular to the first direction, and The second light is irradiated after the first light is irradiated.

8. The method according to claim 7, wherein, The first emitted light from the ink is reflected by a reflector having a center of curvature in the path through which the ink is ejected and a curved outer surface.

9. The method according to claim 1, wherein, The ink is ejected from the inkjet head in a first direction, and The first light and the second light are irradiated from different directions and are simultaneously irradiated onto the ink.

10. An inkjet printing apparatus, comprising: The inkjet head ejects ink containing multiple dispersed particles. The first light irradiation device and the second light irradiation device respectively irradiate the ink being sprayed with light of different wavelengths; A first sensing device, wherein a first emitted light is incident on the first sensing device, wherein the first emitted light is obtained by scattering a first light that is irradiated from the first light irradiation device and incident on the ink; A second sensing device, wherein a second emitted light is incident on the second sensing device, and the second emitted light is obtained by refraction of second light irradiated from the second light irradiation device and incident on the ink; and The processor receives data regarding the first and second emitted light incident on the first and second sensing devices, respectively. Wherein, the first light irradiated by the first light irradiation device has a wavelength of 500 nm or less, and the second light irradiated by the second light irradiation device has a wavelength of 1000 nm or greater. The processor calculates the particle concentration by obtaining data on the number of particles in the ink based on the data on the first emitted light and data on the volume of the ink based on the data on the second emitted light.

11. The inkjet printing apparatus according to claim 10, wherein, The ink is ejected from the inkjet head in a first direction, and The first light irradiation device irradiates the first light in a second direction perpendicular to the first direction.

12. The inkjet printing equipment according to claim 11, wherein, The second light irradiation device is configured to be spaced apart from the first light irradiation device in the first direction and to irradiate the second light in the second direction.

13. The inkjet printing equipment according to claim 12, wherein, The first light irradiation device and the second light irradiation device respectively irradiate the first light and the second light onto different areas in the path through which the ink is sprayed.

14. The inkjet printing equipment according to claim 11, wherein, The first sensing device is positioned opposite the first light irradiation device with respect to the path through which it sprays the ink, and is configured to face the first light irradiation device. The second sensing device is positioned opposite the second light irradiation device with respect to the path through which it sprays the ink, and is configured to face the second light irradiation device.

15. The inkjet printing apparatus according to claim 11, further comprising: The first reflector is configured to be spaced apart from the first light irradiation device. The first reflector has a center of curvature in the path through which the ink is ejected and has a curved outer surface. The first emitted light is reflected from the first reflector and incident on the first sensing device.

16. The inkjet printing apparatus according to claim 15, wherein, The first sensing device is positioned on a first side opposite to the second side where the first reflector is located, with respect to the path through which the ink is ejected.

17. The inkjet printing apparatus according to claim 15, further comprising: The second reflector is configured to be spaced apart from the second light irradiation device. The second reflector has a center of curvature in the path through which the ink is ejected and has a curved outer surface. The second emitted light is reflected from the second reflector and incident on the second sensing device.

18. The inkjet printing apparatus according to claim 11, wherein, The second light irradiation device is configured to irradiate the second light in a direction spaced apart from the first light irradiation device in the first direction and in a direction between the first direction and the second direction. The first light irradiation device and the second light irradiation device respectively irradiate the ink being sprayed with the first light and the second light.

19. The inkjet printing apparatus according to any one of claims 10-18, wherein, The processor stores the data about the first emitted light and the second emitted light according to the different concentrations of the particles in the ink.

20. A method of manufacturing a display device, comprising: Prepare a target substrate comprising a first region and a second region; A first ink containing dispersed particles is sprayed from a first nozzle onto the first region of the target substrate; The first ink ejected from the first nozzle is irradiated with first light and second light of different wavelengths to obtain data about the first emitted light and the second emitted light emitted from the first ink; The concentration of the particles in the first ink is calculated based on the data regarding the first emitted light and the second emitted light; Determine whether the concentration exceeds the error range of the reference value; as well as A second ink containing dispersed particles is ejected from a second nozzle, which is different from the first nozzle. The calculation of the concentration of the particles includes: Based on the data regarding the first emitted light, obtain data regarding the number of particles in the ink; and Data regarding the volume of the ink is obtained based on the data regarding the second emitted light.

21. The method according to claim 20, wherein, The first light has a wavelength of 500 nm or less, and the second light has a wavelength of 1000 nm or greater.

22. The method according to claim 20, wherein, The particles include titanium oxide.

23. The method according to claim 20, wherein, The spraying of the second ink includes: When it is determined that the concentration exceeds the error range of the reference value, the second ink is sprayed from the second nozzle onto the first area.

24. The method according to claim 23, wherein, The first ink and the second ink sprayed onto the first area form a first ink pattern.

25. The method according to claim 20, wherein, The spraying of the second ink includes: spraying the second ink from the second nozzle into the second region when it is determined that the concentration does not exceed the error range of the reference value.

26. The method of claim 25, wherein, The first ink sprayed onto the first area forms a first ink pattern, and The second ink sprayed onto the second region forms a second ink pattern that is different from the first ink pattern.

27. The method of claim 20, further comprising: A third ink containing dispersed particles is sprayed from a third nozzle, which is different from the first nozzle, into the first area.

28. The method of claim 20, further comprising: A third ink containing dispersed particles is sprayed from a third nozzle, which is different from the first nozzle, into the second region.

29. The method of claim 28, further comprising: The first light and the second light are used to illuminate the third ink ejected from the third nozzle to obtain data on the third and fourth emitted light emitted from the third ink. The concentration of the particles in the third ink is calculated based on the data regarding the third emitted light and the fourth emitted light, and it is determined whether the concentration exceeds the error range of the reference value.

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