KR20210037867A - Ink droplet inspecting apparatus and method, inkjet print system having the same - Google Patents

Abstract

Disclosed are a droplet inspection apparatus, a droplet inspection method, and an inkjet printing system including the same. The droplet inspection apparatus according to an embodiment of the present invention is a droplet inspection apparatus for inspecting characteristics of droplets discharged from an inkjet ejection head of an inkjet printing apparatus and landed on a substrate, comprising: a camera module that generates an image of a droplet corresponding to the droplet impacting the substrate; and a processor for obtaining a volume of the droplet from the droplet image.

Description

A droplet inspection device, a droplet inspection method, and an inkjet print system including the same {INK DROPLET INSPECTING APPARATUS AND METHOD, INKJET PRINT SYSTEM HAVING THE SAME}

The present invention relates to a droplet inspection apparatus, a droplet inspection method, and an inkjet printing system including the same, and more particularly, a droplet inspection apparatus and a droplet inspection method capable of inspecting the characteristics of droplets hitting a substrate, and an inkjet print including the same It's about the system.

With the development of inkjet technology, it is used in various fields, such as printing a type or the like on paper, as well as discharging droplets such as ink and used in a manufacturing process of a display device by forming a thin film or patterning.

In an inkjet printing system to which an inkjet technology is applied, a droplet inspection is required to determine whether or not a droplet ejected from an inkjet printhead hits a substrate in a desired shape.

As a conventional droplet inspection apparatus, a drop watcher for real-time inspection of droplets discharged from the inkjet print head during drop was used.

The drop watcher is a three-dimensional measuring device that measures the shape, velocity, volume, and the like of droplets ejected from an inkjet print head and falling. Drop watchers are expensive equipment, and have a large problem of space constraints when they are installed in an inkjet print system, which has a high cost burden.

In addition, in the case of droplet inspection devices that analyze droplets during a fall, there is a difficulty in controlling the external environment for the stability of the inkjet print head, which inhibits the jetting straightness of the inkjet print head due to vibration due to airflow during the fall.

Korean Published Publication No. 10-2019-0100008 (Publication date: 2019.08.28.)

One technical problem to be solved by the present invention is to provide a droplet inspection device, a droplet inspection method, and an inkjet print system including the same, which enables precise analysis of the characteristics of microscopic droplets and facilitates the measurement method by replacing expensive equipment. have.

In order to solve the above technical problem, the present invention provides a droplet inspection apparatus.

A droplet inspection apparatus according to an embodiment of the present invention is a droplet inspection apparatus for inspecting characteristics of droplets that are ejected from an inkjet discharge head of an inkjet printing apparatus and hit a substrate. A camera module that generates a droplet image; And a processor that obtains the volume of the droplet from the droplet image.

According to an embodiment, the camera module may include a first camera provided in a direction parallel to a side surface of the substrate, and generating a droplet image of a droplet side portion corresponding to the droplet.

According to an embodiment, the camera module further includes a second camera provided on an upper end of the substrate and generating a top droplet image corresponding to the droplet, wherein the top droplet image corrects shape error information of the droplet image. It is possible.

According to an embodiment, a hydrophobic protective layer is formed on the substrate to minimize absorption of the droplet.

According to an embodiment, the processor includes: a droplet parameter acquisition processor that obtains droplet surface coordinates from the droplet image and obtains parameters such as a contact angle with the substrate and a radius of a droplet cross section at the substrate contact surface from the droplet surface coordinates; And a droplet volume operation processor that calculates the droplet volume based on the following equation from the parameter.

According to an embodiment, the camera module may acquire the droplet images according to time intervals, and the processor may track the volume behavior of the droplet through the plurality of droplet images acquired by the camera module.

In order to solve the above technical problem, the present invention provides a droplet inspection method.

A droplet inspection method according to an embodiment of the present invention includes: an alignment step of aligning a camera module with a substrate having a constant contact angle and a side surface of the substrate or in a direction parallel to an upper end of the substrate; A droplet image acquisition step of obtaining a droplet image corresponding to a droplet discharged from an inkjet print head and hitting the substrate; A droplet parameter extraction step of obtaining droplet surface coordinates from the droplet image and obtaining a contact angle with the substrate and a radius of a droplet cross section at the substrate contact surface from the droplet surface coordinates; And a droplet volume calculation step of obtaining the volume of the droplet by the following equation using the contact angle and the radius.

In order to solve the above technical problem, the present invention provides an inkjet printing system.

An inkjet printing system according to an embodiment of the present invention includes: an inkjet printhead for discharging droplets; A substrate on which the droplets can be impacted; A UV curing machine for curing by irradiating UV to the droplets hitting the substrate; A droplet inspection device for inspecting the droplets hitting the substrate; And a controller configured to control the operation of at least one of the inkjet discharge head or the UV curing machine by receiving characteristic information on the droplet from the droplet inspection apparatus, wherein the droplet inspection apparatus includes any one of claims 1 to 5 It may be a droplet inspection device of one claim.

According to an embodiment of the present invention, as a droplet inspection apparatus for analyzing the characteristics of droplets hitting a substrate, there is an advantage in that the linearity of the inkjet print head can be relaxed and external factors such as airflow can be excluded.

According to another embodiment of the present invention, as a droplet inspection device that analyzes the characteristics of droplets hitting a substrate, it is possible to secure error accuracy by having a measurement error of 1% or less for fine-sized droplets used in the display process. There is an advantage.

According to another embodiment of the present invention, the processor obtains 3D information such as the droplet volume with 2D information such as the radius and contact angle of the droplets hit on the substrate generated by the camera module, so that measurement is easy but expensive. It has the advantage of being able to replace dimensional measurement equipment.

According to another embodiment of the present invention, there is an advantage that a droplet inspection device including a processor can manage the quality of an inkjet print system by a controller by grasping the correlation between the inkjet discharge head and the curing machine according to droplet volume information and droplet volume deviation. have.

1 is a block diagram of a droplet inspection apparatus according to an embodiment of the present invention.
2 is a diagram illustrating a process of acquiring a droplet parameter to inspect droplet characteristics in a droplet inspection apparatus according to an embodiment of the present invention.
3(a) and 3(b) are views showing droplet images acquired by a camera module of a droplet inspection apparatus according to an embodiment of the present invention.
4 is a flow chart showing a droplet inspection method according to an embodiment of the present invention.
5 is a diagram showing an inkjet printing system according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In the present specification, when a component is referred to as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed therebetween. In addition, in the drawings, the shape and size are exaggerated for effective description of the technical content.

Further, in various embodiments of the present specification, terms such as first, second, and third are used to describe various elements, but these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. In addition, in the present specification,'and/or' has been used to mean including at least one of the elements listed before and after.

In the specification, expressions in the singular include plural expressions unless the context clearly indicates otherwise. In addition, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, components, or a combination thereof described in the specification, and one or more other features, numbers, steps, or configurations. It is not to be understood as excluding the possibility of the presence or addition of elements or combinations thereof. In addition, in the present specification, "connection" is used to include both indirectly connecting a plurality of constituent elements and direct connecting.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a block diagram of a droplet inspection apparatus 400 according to an embodiment of the present invention, and FIG. 2 is a droplet parameter acquisition in order to inspect droplet characteristics in a droplet inspection apparatus 400 according to an embodiment of the present invention. 3(a) and 3(b) are diagrams for explaining the process, and FIG. 3(a) and FIG. 3(b) illustrate droplet images 411a and 411b acquired by the camera module 410 of the droplet inspection apparatus 400 according to an embodiment of the present invention. It is a drawing showing.

Hereinafter, each component constituting the droplet inspection apparatus 400 according to an embodiment of the present invention will be described in detail.

1 to 3(b), the droplet inspection apparatus 400 according to an embodiment of the present invention is discharged from the inkjet discharge head 100 of the inkjet print system 10 to be described later, and the substrate 200 It is possible to check the characteristics of the droplet (D) hit by.

At this time, the ink may be any one of acrylic, epoxy, silicone, or rubber resins, or a mixture thereof, and preferably, a UV curable resin curable by UV light. When the ink hits the substrate 200, due to the characteristics of the hydrophobic substrate 200, the impacted droplet D may have a contact angle θ with the substrate 200 at an acute angle.

The droplet inspection apparatus 400 may include a camera module 410 and a processor 420.

The camera module 410 may generate a droplet image corresponding to the droplet D landed on the substrate 200. The camera module 410 may include a first camera 411 and a second camera 412.

In addition, the camera module 410 may acquire a droplet image according to an automatically or manually set time interval during the ejection process of the inkjet print head 100. The camera module 410 may determine the shape deformation of the droplet D that has landed on the substrate 200 by acquiring the droplet image 411a according to the time interval.

As shown in FIG. 3(a), the first camera 411 is provided in a direction parallel to the side of the substrate 200, and a droplet image 411a of the side of the droplet corresponding to the droplet in the direction parallel to the substrate 200 Can be created.

As shown in FIG. 3B, the second camera 412 may be provided on the upper surface of the substrate 200 and may generate an upper surface droplet image 412a corresponding to the droplet in a vertical direction. The top droplet image 412a may be modeled as an ideal droplet image by correcting shape error information of the droplet image 411a. More specifically, the second camera 412 may generate the top droplet image 412a in order to evaluate and correct the spread of the droplet D hitting the substrate 200 if it is not symmetric.

The processor 420 may obtain the volume of the droplet from the droplet image 411a. The processor 420 may include a droplet parameter acquisition processor 421 and a droplet volume calculation processor 422.

The droplet parameter acquisition processor 421 may detect an edge region from the droplet image 411a to extract a droplet profile, and obtain droplet surface coordinates. The droplet parameter acquisition processor 421 may obtain parameters such as a contact angle θ with a substrate, a radius R of a droplet cross section at the substrate contact surface from the droplet profile and droplet surface coordinates.

When the droplet spreading is asymmetric, the droplet parameter acquisition processor 421 may obtain a radius in each edge region from the center and obtain a radius R based on an average value. In addition, the droplet parameter acquisition processor 421 may obtain a contact angle θ formed between the substrate and the edge region of the droplet. The contact angle according to an embodiment (θ) may be, the radius (R) relative to the liquid surface of the top surface coordinates obtained droplet video contact angle (θ) at the reference position of the droplet image that corresponds to (412a).

The droplet volume operation processor 422 may obtain the droplet volume by substituting the parameter into Equation 1 below.

[Equation 1]

In Equation 1, V denotes the volume of the droplet hit on the substrate, R denotes the radius of the cross section of the droplet at the contact surface of the substrate, and θ denotes the contact angle with the substrate.

The processor 420 according to an embodiment may track the volume behavior of a droplet through a plurality of droplet images 411a and 412b acquired by the camera module 410. Accordingly, the processor 420 may track a droplet landing process according to a droplet ejection frequency, ejection droplet number, curing time, and curing temperature, and a volume behavior in the drying process. That is, the processor 420 may match each droplet image 411a based on the droplet ejection amount, ejection number, curing time, and curing temperature at a specific location. In addition, the processor 420 may measure changes in the radius R and the contact angle θ according to the amount of impact of the droplet at an arbitrary time.

The processor 420 according to another exemplary embodiment may track the pattern formation behavior in the inkjet printing process by moving the stage 600 on which the substrate 200 is stacked.

A droplet inspection method according to the droplet inspection apparatus 400 according to an embodiment of the present invention having the above components will be described.

4 is a flow chart showing a droplet inspection method according to an embodiment of the present invention.

Referring to FIG. 4, the droplet inspection method according to an embodiment of the present invention includes an alignment step (S10), a droplet image acquisition step (S20), a droplet parameter extraction step (S30), and a droplet volume calculation step (S40). I can.

In the alignment step S10, the camera module may be aligned in a direction parallel to a side surface of a substrate and a side surface of the substrate or an upper end of the substrate having a constant contact angle. In the alignment step (S10), an inkjet print head and a UV curing device to be described later may be provided in an arbitrary area on the upper surface of the substrate.

In the droplet image acquisition step (S20 ), a droplet image corresponding to droplets discharged from the inkjet print head and landed on the substrate may be obtained.

In the droplet parameter extraction step S30, droplet surface coordinates may be obtained from the droplet image. In the droplet parameter extraction step, the contact angle with the substrate and the radius of the cross section of the droplet at the substrate contact surface may be obtained from the droplet surface coordinates.

In the droplet volume calculation step S40, the droplet volume may be obtained by substituting the droplet parameters of the contact angle and the radius into Equation 1 below.

[Equation 1]

In Equation 1, V is the volume of the droplet landed on the substrate, R is the radius of the cross section of the droplet at the substrate contact surface, and θ is the contact angle with the substrate.

Hereinafter, an inkjet print system 10 including a droplet inspection apparatus 400 according to an embodiment of the present invention will be described.

5 is a diagram showing an inkjet print system 10 according to an embodiment of the present invention.

Referring to FIG. 5, the inkjet print system 10 includes an inkjet print head 100, a substrate 200, a UV curing machine 300, a droplet inspection device 400, a controller 500, and further, a stage 600 ) And a gantry 700 may be further included.

The inkjet print head 100 may move along the entire area of the substrate 200 by driving a head driver (not shown) on the gantry 700 and may move to an arbitrary position.

The inkjet print head 100 can discharge droplets onto the substrate 200. The inkjet print head 100 may discharge droplets onto the substrate 200 by controlling a volume of droplets ejected from an arbitrary position, a number of ejections, and the like. The controller 500 may include a nozzle (not shown) to control the amount of ejection of the inkjet print head 100 once, the number of ejections, or whether or not some nozzles are opened or closed.

The inkjet print head 100 may include tens or thousands of nozzles (not shown) and an ink supply unit (not shown) along a droplet discharge path.

The nozzle (not shown) may discharge fine-sized ink in the form of droplets.

The ink supply unit (not shown) may be installed on the gantry 700 or may be provided inside the inkjet print head 100.

The substrate 200 may be any one of a display panel such as an LCD, an OLED, and a PDP panel, a touch panel, or a window panel, or a panel formed of a plurality of layers by stacking and bonding them. Further, the substrate 200 may include a flexible panel made of a flexible material capable of bending, folding, and rolling, as well as a rigid panel.

The substrate 200 is provided on the lower surface of the inkjet print head 100 so that droplets may be impacted. The substrate 200 minimizes absorption of the impacted droplet D, thereby ensuring safety of droplet behavior. In addition, the substrate 200 may have a constant contact angle with the droplets upon landing under the same type and condition by minimizing droplet absorption.

According to an embodiment, the substrate 200 may be treated with a hydrophobic protective layer to minimize the absorption of droplets. The substrate 200 may have a hydrophobic protective layer formed by spin coating. According to another embodiment, the substrate 200 may have a uniform surface roughness to minimize liquid droplet absorption. According to another embodiment, the substrate 200 may undergo a surface planarization process according to polishing.

The UV curing machine 300 may be cured by irradiating UV to the droplets D hit on the substrate 200. The curing is to minimize shape change by reducing the fluidity of liquid droplets. The degree of curing may be determined in consideration of the correlation between the type of ink and the capacity and performance of the inkjet printing system 10 and the degree of curing. The UV curing machine 300 may be a UV LED that irradiates UV light.

The UV curing machine 300 may be driven in one process unit at the same time as the droplets are discharged on the gantry 700. The UV curing machine 300 may be provided to be adjacent to the inkjet print head 100. The UV curing machine 300 may be provided on one side of the inkjet print head 100 on the gantry 700 and may move along the entire area of the substrate 200. More specifically, the inkjet print head 100 may be provided on the gantry 700 in the front of the droplet discharge direction, and the UV curing machine 300 may be provided at the rear.

The UV curing machine 300 may irradiate UV toward the substrate 200 at the same time or at the same time as the droplet is discharged. The controller 500 may adjust the curing time and temperature range of the UV curing machine.

The controller 500 may control the operation of at least one of the inkjet discharge head 100 and the UV curing machine 300 by receiving characteristic information on the droplet from the droplet inspection apparatus 400. The controller 500 may control the operation of the inkjet print head 100, such as a single discharge amount or the number of discharges at an arbitrary point. The controller 500 may control the operation of the UV curing machine 300 to adjust the UV irradiation time and intensity of UV light at an arbitrary point. That is, the controller 500 may adjust a droplet volume change according to a discharge amount of the inkjet print head 100 and/or a droplet volume change according to a curing degree of the UV curing machine 300.

To this end, when the droplet volume obtained by the processor 420 is smaller than the preset droplet volume, the controller 500 moves the inkjet print head 100 and commands the inkjet print head 100 to re-discharge at the corresponding position. Can be called.

The stage 600 may support the substrate 200 and move the substrate 200 back and forth.

The gantry 700 may support the inkjet print head 100. The gantry 700 may provide a moving path of the inkjet print head 100 or the UV curing machine 300 by an area corresponding to the substrate 200.

As described above, the present invention has been described in detail using preferred embodiments, but the scope of the present invention is not limited to specific embodiments, and should be interpreted by the appended claims. In addition, those who have acquired ordinary knowledge in this technical field should understand that many modifications and variations are possible without departing from the scope of the present invention.

10: inkjet printing system
100: inkjet print head
200: substrate
300: UV curing machine
400: droplet inspection device 410: camera module
411: first camera 411a: droplet image
412: second camera 412a: upper surface droplet image
420: processor 421: droplet parameter acquisition processor
422: droplet volume computation processor
500: controller
600: stage
700: gantry
D: Impacted droplet R: Radius
θ : contact angle

Claims (8)

A droplet inspection apparatus for inspecting characteristics of droplets discharged from an inkjet ejection head of an inkjet printing apparatus and landed on a substrate,
A camera module that generates a droplet image corresponding to a droplet hit on the substrate; And
And a processor that obtains the volume of the droplet from the droplet image.
The method of claim 1,
The camera module,
A droplet inspection apparatus comprising a first camera provided in a direction parallel to the side surface of the substrate and generating a droplet image of a droplet side portion corresponding to the droplet.
The method of claim 2,
The camera module,
Further comprising a second camera provided on the top of the substrate and generating a top surface droplet image corresponding to the droplet,
The droplet inspection apparatus, wherein the upper surface droplet image is capable of correcting shape error information of the droplet image.
The method of claim 1,
A droplet inspection apparatus in which a hydrophobic protective layer is formed on the substrate to minimize absorption of the droplet.
The method of claim 1,
The processor is
A droplet parameter acquisition processor for obtaining droplet surface coordinates from the droplet image and obtaining parameters such as a contact angle with the substrate and a radius of a droplet cross section at the substrate contact surface from the droplet surface coordinates; And
And a droplet volume calculation processor that calculates the droplet volume based on the following equation from the parameter.

In the above equation, V is the volume of the impacted droplet, r is the radius of the cross section of the droplet at the contact surface of the substrate, and θ is the contact angle with the substrate.
The method of claim 1,
The camera module acquires the droplet image according to a time interval, and the processor tracks the volume behavior of the droplet through the plurality of droplet images acquired by the camera module.
An alignment step of aligning the camera module in a direction parallel to a substrate having a constant contact angle and a side surface of the substrate or an upper end of the substrate;
A droplet image acquisition step of acquiring a droplet image corresponding to droplets discharged from the inkjet print head and hit on the substrate;
A droplet parameter extraction step of obtaining droplet surface coordinates from the droplet image and obtaining a contact angle with the substrate and a radius of a droplet cross section at the substrate contact surface from the droplet surface coordinates; And
And a droplet volume calculation step of calculating the volume of the droplet using the following equation using the contact angle and the radius.

In the above equation, V is the volume of the impacted droplet, R is the maximum radius of the cross section of the droplet, and θ is the contact angle between the substrate and the droplet.
An inkjet print head for discharging droplets;
A substrate on which the droplets can be impacted;
A UV curing machine for curing by irradiating UV to the droplets hitting the substrate;
A droplet inspection device for inspecting the droplets hitting the substrate; And
And a controller configured to receive characteristic information on the droplet from the droplet inspection device and control an operation of at least one of the inkjet discharge head and the UV curing machine,
The droplet inspection apparatus is the droplet inspection apparatus according to any one of claims 1 to 5, an inkjet printing system.

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