Method for inkjet luminescence inspection

Abstract

The inkjet droplet emission inspection method of the present disclosure may include a printing step of printing an ink droplet on one side of an inspection unit; a light source irradiation step of irradiating a light source on one side of the inspection unit; an emission light reception step in which a camera unit receives emission light reflected from one side of the inspection unit; an emission light measurement step in which a control unit that receives an electrical signal from the camera unit measures the intensity of the emission light; and an analysis step in which the control unit analyzes the number of particles within the ink droplet printed on one side of the inspection unit through the intensity of the emission light measured in the emission light measurement step.

Description

Technology Field

[0001] The present disclosure relates to an inkjet droplet emission inspection method. Background Technology

[0002] In general, inkjet printing processes have been primarily used to fabricate display panels using light-emitting nanoparticle materials such as Nano-LED (light emitting diode), electroluminescent quantum dots (QD (quantum dot)-EL (electroluminescence)), and photoluminescent quantum dots (QD (quantum dot)-PL (photoluminescence)).

[0003] In conventional inkjet printing processes, in order to quantitatively apply nanoparticle materials using the inkjet printing process, it is necessary to quantitatively measure the number of particles coming out of the inkjet nozzle and, based on this, precisely control the amount of droplets coming out of the nozzle.

[0004] Conventional inkjet droplet measurement methods measured the size of a droplet by capturing a 2D or 3D image of the droplet and thereby measured the volume of the droplet. These conventional inkjet droplet measurement methods assumed that the particle concentration within the droplet was constant and measured the volume of the droplet coming out of the nozzle, using a control method to maintain a constant volume of the droplet coming out of the inkjet nozzle.

[0005] However, if sedimentation or aggregation of particles occurred within the ink, the particle concentration would change, and there was a problem in that the amount of particles inside could vary even if the volume of the droplet remained constant.

[0006] In addition, when multiple nozzles exist in the inkjet head, there was a problem in that the distribution of particle numbers could vary depending on the position of the nozzles within the head.

[0007] Therefore, it was necessary to develop technology capable of quantitatively determining the amount of particles ejected from the nozzle through the inkjet process and controlling the process based on this. Prior art literature

[0008] (Patent Document 0001) KR 10-2022-0033603 A The problem to be solved

[0009] According to one aspect of the present disclosure, an inkjet droplet emission inspection method is provided to quantitatively determine the amount of luminescent nanoparticles in an inkjet droplet and to maintain a constant number of printed nanoparticles through droplet volume control. means of solving the problem

[0010] According to the present disclosure, an inkjet droplet emission inspection method may include a printing step of printing an ink droplet on one side of an inspection unit; a light source irradiation step of irradiating a light source on one side of the inspection unit; an emission light reception step in which a camera unit receives emission light reflected from one side of the inspection unit; an emission light measurement step in which a control unit that receives an electrical signal from the camera unit measures the intensity of the emission light; and an analysis step in which the control unit analyzes the number of particles within the ink droplet printed on one side of the inspection unit through the intensity of the emission light measured in the emission light measurement step.

[0011] According to one embodiment, the emission light receiving step may further include a filtering step that filters the light so that only light corresponding to a wavelength of 400 nm or more of the emission light passes through when the emission light is received by the camera unit.

[0012] According to one embodiment, the inkjet droplet emission inspection method of the present disclosure may further include a drying step for drying the ink droplet printed on the inspection unit after the printing step.

[0013] According to one embodiment, the printing step may further include a correction step of printing the ink droplet on one side of the inspection unit through a plurality of nozzles and, after the analysis step, adjusting the individual discharge amount of the plurality of nozzles to correct the discharge dispersion between the plurality of nozzles.

[0014] According to one embodiment, the inkjet droplet emission inspection method of the present disclosure may further include a defect determination step after the correction step, wherein a defective nozzle among the plurality of nozzles is excluded from the printing process.

[0015] According to one embodiment, the printing step prints a plurality of ink droplets on one side of the inspection unit, and the analysis step can quantitatively analyze the number of particles in each individual droplet of the plurality of ink droplets.

[0016] The features and advantages of the present disclosure will become more apparent from the following detailed description based on the accompanying drawings.

[0017] Prior to this, terms and words used in this specification and claims should not be interpreted in their ordinary and dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of this disclosure, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Effects of the invention

[0018] According to one embodiment of the present disclosure, there is an effect of maintaining a constant number of nanoparticles in the printed ingjet droplets.

[0019] According to one embodiment of the present disclosure, by measuring the deviation in the amount of particles ejected from an inkjet nozzle and correcting it, it is possible to produce a stain-free, high-quality display panel.

[0020] According to one embodiment of the present disclosure, there is an effect of being able to quantitatively determine the amount of luminescent nanoparticles in an inkjet droplet. Brief explanation of the drawing

[0021] FIG. 1 is a flowchart of an inkjet droplet emission inspection method according to one embodiment. FIG. 2 is a conceptual diagram illustrating a printing step according to one embodiment. FIG. 3 is a conceptual diagram illustrating a light source irradiation step according to one embodiment. FIG. 4 is a conceptual diagram illustrating a drying step according to another embodiment. FIG. 5 is a conceptual diagram illustrating multiple inkjet droplets printed on an inspection unit through multiple nozzles. Figure 6 is a graph showing light generated from a light source and emitted light emitted from nanoparticles. FIG. 7 is a drawing showing an image of a camera receiving emitted light without using a filter according to one embodiment. FIG. 8 is a diagram illustrating an image in which a camera receives emitted light using a filter according to one embodiment. Specific details for implementing the invention

[0022] In assigning reference numerals to the components of the drawings, identical components are assigned the same reference numeral whenever possible, even if they are shown in different drawings, and similar components are assigned similar reference numerals.

[0023] The terms used to describe an embodiment of the present disclosure are not intended to limit the present disclosure. It should be understood that singular expressions include plural expressions unless otherwise specified in the context.

[0024] Drawings may be schematic or exaggerated for the purpose of illustrating embodiments. In this document, expressions such as “have,” “may have,” “include,” or “may include” indicate the presence of such features (e.g., numerical values, functions, operations, or components such as parts) and do not exclude the presence of additional features.

[0025] Terms such as "one," "other," "another," "first," and "second" are used to distinguish one component from another, and the components are not limited by these terms.

[0026] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the attached drawings.

[0027] FIG. 1 is a flowchart of an inkjet droplet emission inspection method according to one embodiment, FIG. 2 is a conceptual diagram illustrating a printing step according to one embodiment, FIG. 3 is a conceptual diagram illustrating a light source irradiation step according to one embodiment, FIG. 4 is a conceptual diagram illustrating a drying step according to another embodiment, FIG. 5 is a conceptual diagram illustrating a plurality of inkjet droplets printed on an inspection part through a plurality of nozzles, FIG. 6 is a graph showing light generated from a light source and emitted light emitted from nanoparticles, FIG. 7 is a diagram illustrating an image in which a camera receives emitted light without using a filter according to one embodiment, FIG. 8 is a diagram illustrating an image in which a camera receives emitted light using a filter according to one embodiment.

[0028] Referring to FIGS. 1 to 8, the inkjet droplet emission inspection method of the present disclosure may include a printing step (S1), a light source irradiation step (S2), an emitted light reception step (S3), an emitted light measurement step (S4), and an analysis step (S5).

[0029] The printing step (S1) may be a step of printing an inkjet droplet (d) on an upper side of an inspection unit (10) through an inkjet nozzle (N). The printing step (S1) may print multiple ink droplets (d) on an upper side of an inspection unit (10) through multiple inkjet nozzles (N). The printing step (S1) may quantitatively apply a liquid droplet (d) or a light-emitting nanoparticle material in the form of ink onto a substrate. The light-emitting nanoparticle material may be a semiconductor particle of nanometer (nm) to micrometer (um) size capable of emitting light either by itself or by external stimulation.

[0030] The inspection unit (10) may be a substrate for inspecting an inkjet droplet (d), but its shape may not be limited as long as it can print and inspect the inkjet droplet (d). The inspection unit (10) may be a test substrate on which the inkjet droplet (d) lands. The inspection unit (10) may be made of a DPC (drop placement check) film, an ETFE (ethylene tetra fluoro ethylene) film, or glass, etc. The inspection unit (10) may be water-repellent and the surface on which the inkjet droplet (d) lands may have hydrophobic properties.

[0031] Inkjet printing technology may be a technology that forms a liquid droplet (d) into an ink form and quantitatively applies it onto a substrate. The liquid droplet (d) may require precise control to apply it quantitatively at a specific location. Such inkjet printing technology can be used in processes for manufacturing display panels, such as thin film encapsulation processes and color filter manufacturing processes.

[0032] The inkjet ink may be an RGB color filter, or one or a mixture of acrylic, epoxy, silicone, or rubber resins, and preferably a UV-curable resin capable of curing by UV light. Although there are no restrictions on the type of inkjet ink, it is preferable to use an ink that does not volatilize in the atmosphere and thus does not cause a change in the volume of the ink droplet during measurement.

[0033] In addition, the inkjet droplet emission inspection method of the present disclosure may further include a drying step for drying the ink droplet (d) printed on the inspection unit (10) after the printing step (S1). The drying step may be performed when the ink droplet (d) is opaque or when the inspection result of the ink droplet (d) is inaccurate.

[0034] The light source irradiation step (S2) may be a step of irradiating a light source of a constant wavelength using a light unit (30) to scan an inkjet droplet (d) printed on one side of the inspection unit (10). The light source irradiation step (S2) may be a step for photoluminescence (PL) inspection utilizing the characteristic that a material emits light again when it receives light. In the light source irradiation step (S2), when a semiconductor material such as a quantum dot or LED absorbs short wavelength light through light source irradiation, it may emit light of a longer wavelength (photoluminescence).

[0035] The light receiving step (S3) may be a step of receiving emitted light reflected from one side of the inspection unit (10) to the camera unit (20).

[0036] In addition, the light receiving step (S3) may further include a filtering step for filtering the emitted light received by the camera unit (20). The filtering step may be for detecting defects or quantifying the amount of material by using a wavelength filter such as a dichroic filter or a filter unit (21) such as a spectrometer to split and quantify the emitted light. Referring to FIG. 6, the filtering step may filter so that only the emitted light corresponding to a wavelength of 400 nm or more passes through and is received by the camera unit (20). That is, the light (a) generated from the light source may be less than 400 nm, which may be 365 nm in one embodiment, and may not pass through the filter unit (21) because the transmittance is significantly lower than the reflectance when passing through the filter unit (21). And the emitted light (b) emitted from the nanoparticle may be 400 nm or more, which may be 650 nm in one embodiment, and may pass through the filter unit (21) because the transmittance is significantly higher than the reflectance when passing through the filter unit (21). FIG. 7 shows the camera unit (20) receiving emitted light without using the filter unit (21), and it can be seen that both the emitted light emitted from the nanoparticle (P) and the foreign substance (F) are received. FIG. 8 shows the camera unit (20) receiving emitted light while using the filter unit (21), and it can be seen that the emitted light emitted from the nanoparticle (P) is received, while the emitted light emitted from the foreign substance (F) is filtered (shown in gray in FIG. 8) and is not received. Since the wavelength of the emitted light reflected from the nanoparticle (P) is 400 nm or more and the wavelength of the emitted light reflected from the foreign substance (F), etc. is less than 400 nm (365 nm in one embodiment), only the emitted light corresponding to a wavelength of less than 400 nm can be filtered through the filtering step. That is, the camera unit (20) can analyze the number of nanoparticles (P) accurately by receiving only the emitted light corresponding to a wavelength of 400 nm or more.

[0037] The emission light measurement step (S4) may be a step in which a control unit that receives an electrical signal from a camera unit (20) measures the intensity of the emission light.

[0038] The analysis step (S5) may be a step in which the control unit quantitatively analyzes the number of particles in the droplets (d) of a plurality of ink droplets printed on one side of the inspection unit (10) through the intensity of the emitted light measured in the emitted light measurement step (S4).

[0039] In addition, the inkjet droplet emission inspection method of the present disclosure may further include a correction step after the analysis step (S5) to correct the discharge dispersion between the plurality of inkjet nozzles (N) by adjusting the individual discharge amount of the plurality of inkjet nozzles (N). That is, the correction step may quantitatively analyze the number of particles in the droplets (d) of the plurality of ink droplets printed on one side of the inspection unit (10) in the analysis step (S5) and adjust the individual discharge amount of the inkjet nozzle (N) corresponding to the position of each droplet (d) printed on the inspection unit (10) among the plurality of droplets (d).

[0040] In addition, the inkjet droplet emission inspection method of the present disclosure may further include a defect determination step after the correction step, in which a defective nozzle among a plurality of inkjet nozzles (N) is excluded from the inkjet printing process. That is, the defect determination step may exclude an inkjet nozzle (N) among a plurality of inkjet nozzles (N) that is not controlled in terms of discharge volume or is not operating from the inkjet printing process.

[0041] The present disclosure has been described in detail above through specific embodiments. The embodiments are intended to specifically explain the present disclosure, and the present disclosure is merely illustrative of the invention and is not intended to limit the appended claims. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims. Explanation of the symbols

[0042] 10: Inspection Department, 20: Camera Department 21: Filter section, 30: Light section d: droplet, N: inkjet nozzle P: Nanoparticles, F: Foreign substances

Claims

Claim 1 An inkjet droplet emission inspection method comprising: a printing step of printing an ink droplet on one side of an inspection unit; a light source irradiation step of irradiating a light source on one side of the inspection unit; an emission light reception step in which a camera unit receives emission light reflected from one side of the inspection unit; an emission light measurement step in which a control unit that receives an electrical signal from the camera unit measures the intensity of the emission light; and an analysis step in which the control unit analyzes the number of particles within the ink droplet printed on one side of the inspection unit through the intensity of the emission light measured in the emission light measurement step; wherein the ink droplet is a UV-curable resin, the light source irradiation step irradiates a UV light source, and further comprises a drying step in which the ink droplet printed on the inspection unit is cured with the UV light source after the printing step. Claim 2 The inkjet droplet emission inspection method according to claim 1, wherein the emission light receiving step further comprises a filtering step for filtering so that only light corresponding to a wavelength of 400 nm or more of the emission light passes through when the emission light is received by the camera unit. Claim 3 delete Claim 4 An inkjet droplet emission inspection method according to claim 1, wherein the printing step further comprises printing the ink droplet on one side of the inspection unit through a plurality of nozzles, and after the analysis step, a correction step for correcting the discharge dispersion between the plurality of nozzles by adjusting the individual discharge amounts of the plurality of nozzles. Claim 5 An inkjet droplet emission inspection method according to claim 4, further comprising a defect determination step of excluding a defective nozzle among the plurality of nozzles from the printing process after the correction step. Claim 6 An inkjet droplet emission inspection method according to claim 1, wherein the printing step prints a plurality of ink droplets on one side of the inspection unit, and the analysis step quantitatively analyzes the number of particles in each individual droplet of the plurality of ink droplets.

Images