KR102473673B1 - Nozzle pressure control apparatus and method - Google Patents

Abstract

A nozzle pressure control device and a nozzle pressure control method are disclosed. An apparatus for controlling nozzle pressure according to an embodiment of the present invention includes an inkjet print head having nozzles capable of ejecting ink; a light irradiation unit capable of irradiating light toward the nozzle end; a vision capable of generating an image of the nozzle end; and a controller including a negative pressure control module interposed between the reservoir and the nozzle and capable of adjusting an ink ejection pressure applied to the nozzle based on the image generated by the vision.

Description

Nozzle pressure control device and nozzle pressure control method {NOZZLE PRESSURE CONTROL APPARATUS AND METHOD}

The present invention relates to a nozzle pressure control device and a nozzle pressure control method, and more particularly, to a nozzle pressure control device and nozzle pressure control method used in an inkjet printing system.

Inkjet technology is a non-impact printing technology that sprays ink through fine-sized nozzles to apply droplets in desired shapes to print media. As inkjet technology develops, not only printing type on paper, but also manufacturing processes such as display devices, organic light emitting diodes (OLED), printed circuit boards (PCBs), solar cells, sensors, etc. by forming or patterning thin films of complex shapes. It is used in various fields such as

Unlike general type and graphic printing, the need to precisely control nozzle pressure increases in order to accurately land ink droplets at desired positions when manufacturing electronic devices.

In order to eject an accurate amount of ink, a meniscus, which is a curved surface in which ink is inwardly concave by capillary action, must be maintained with respect to the end of the nozzle before the inkjet printing process. The meniscus is a negative pressure applied in the opposite direction of gravity to prevent ink from flowing in the inkjet print head facing in the direction of gravity. Meniscus adjustment is required whenever there is a change in equipment specifications and conditions, such as newly installing equipment or replacing ink or head.

In the conventional nozzle pressure control device, the meniscus pressure is adjusted by an operator visually finding a point at which ink does not flow according to the nozzle pressure. In the conventional method, there is a problem in that the meniscus is different due to different set values even if the equipment condition is set in the same equipment by the operator's arbitrary judgment because the standard is ambiguous.

The ink ejection amount is finely changed according to the meniscus pressure value. In a specific specification, when the meniscus is not constant and changes minutely, the ink ejection amount varies, which leads to deterioration of the quality of the display device. It is important to set the ideal meniscus pressure value of the RGB pixel pattern to realize the image of the display device with the best quality.

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Korean Registration No. 10-1989375 (Announcement date: 2019.06.14.)

One technical problem to be solved by the present invention is to provide a nozzle pressure control device and a nozzle pressure control method capable of providing accurate setting conditions for meniscus pressure.

In order to solve the above technical problem, the present invention provides a nozzle pressure control device.

A nozzle pressure control device according to an embodiment of the present invention includes an inkjet print head having nozzles capable of ejecting ink; a light irradiation unit capable of irradiating light toward the nozzle end; a vision capable of generating an image of the nozzle end; and a controller connected to a reservoir capable of supplying ink to the nozzle based on the image generated by the vision and having a negative pressure control module capable of adjusting an ink ejection pressure applied to the nozzle.

According to an embodiment, the vision may be arranged to face the light irradiation part with the nozzle end interposed therebetween.

According to an embodiment, the light irradiation unit may emit visible light in an infrared or near-infrared region.

According to an embodiment, the controller may further include a position movement module capable of moving the light irradiation unit in a direction corresponding to a movement direction of the inkjet print head.

According to an embodiment, the controller may further include an angle adjustment module capable of adjusting an irradiation angle of the light irradiation unit.

In order to solve the above technical problem, the present invention provides a nozzle pressure control method.

A nozzle pressure control method according to an embodiment of the present invention includes the steps of (a1) setting an ink ejection pressure applied to a nozzle; (a2) generating an image of the nozzle end; and an (a3) system for adjusting the ink discharge pressure by determining whether the image is within a preset reference range, in terms of the ink discharge pressure.

According to an embodiment, in the step (a3), if the image is out of a preset reference range, the steps (a1) and (a2) may be repeatedly operated.

According to an embodiment, a step (a0) of positioning the light irradiation unit and the vision face each other with the nozzle end interposed therebetween may be further included.

According to an embodiment of the present invention, by providing a light irradiation unit and a vision, there is an advantage in securing meniscus error precision by minimizing an error range of meniscus pressure.

According to one embodiment of the present invention, in a state where the light irradiated from the light irradiation unit is focused on the end of the nozzle, the controller constantly controls the meniscus pressure based on the image provided by the vision to stably set the meniscus pressure. And there are advantages that can be provided accurately.

According to another embodiment of the present invention, the angle adjustment module supports and fixes the light irradiation unit or the vision at an angle at an angle, so that the three-dimensional shape of the ink formed on the nozzle end is easily grasped, and some of the ink ejected from the nozzle scatters There is an advantage in preventing contamination of the light irradiation unit or vision in advance.

1 is a schematic diagram showing a nozzle pressure control device according to an embodiment of the present invention.
2(a) and 2(b) are schematic diagrams showing a nozzle pressure control device according to an embodiment of the present invention and an operating state of an inkjet printing system after the nozzle pressure control device operates.
3 is a view showing an inkjet print head provided on a printed board according to an embodiment of the present invention.
4(a) to 4(c) are front cross-sectional views showing an ink state at a nozzle end according to meniscus pressure according to an embodiment of the present invention.
5(a) to 5(c) are views showing a state in which ink is applied to a printing medium by discharging ink at the meniscus pressure of FIGS. 4(a) to 4(c).
6(a) to 6(c) are views showing different images formed according to operating conditions of the light irradiation unit and the vision according to an embodiment of the present invention.
7 is a flowchart showing a nozzle pressure control method according to an embodiment of the present invention.

Hereinafter, preferred 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 will be thorough and complete and the spirit of the present invention will be sufficiently conveyed to those skilled in the art.

In this specification, when an element is referred to as being on another element, it means that it may be directly formed on the other element or a third element may be interposed therebetween. Also, in the drawings, shapes and sizes are exaggerated for effective description of technical content.

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

In the specification, expressions in the singular number include plural expressions unless the context clearly dictates otherwise. In addition, the terms "comprise" or "having" are intended to designate that the features, numbers, steps, components, or combinations thereof described in the specification exist, but one or more other features, numbers, steps, or components. It should not be construed as excluding the possibility of the presence or addition of elements or combinations thereof. In addition, in this specification, "connection" is used to mean both indirectly and directly connecting a plurality of components.

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, the detailed description will be omitted.

For convenience of explanation, in the XYZ Cartesian coordinate system, the first direction may indicate the X axis and the second direction may indicate the Y axis, but is not limited thereto. At this time, the second direction is orthogonal to the first direction.

Figure 1 is a schematic diagram showing a nozzle pressure control device 10 according to an embodiment of the present invention, Figures 2 (a) and 2 (b) is a nozzle pressure control device 10 according to an embodiment of the present invention 3 is a schematic diagram showing an operating state of an inkjet print system after operation of the nozzle pressure control device 10 and FIG. 3 is a diagram showing an inkjet print head provided on a printed circuit board according to an embodiment of the present invention; ) to FIG. 4(c) are front cross-sectional views showing the ink state of the nozzle end according to the meniscus pressure according to an embodiment of the present invention, and FIGS. 5(a) to 5(c) are FIG. 4(a) 4(c) is a diagram showing a state in which ink is applied to a printing medium by ejecting ink at the meniscus pressure, and FIGS. It is a diagram showing different images formed according to operating conditions of the irradiation unit 200 and the vision 300.

Hereinafter, each component constituting the nozzle pressure control device 10 according to an embodiment of the present invention will be described in detail.

The inkjet print system includes a reservoir 120 for accommodating ink, at least one inkjet print head 100 having a plurality of nozzles 110 configured to receive ink from the reservoir 120 and discharge ink, and nozzles. The nozzle pressure control device 10 for adjusting the meniscus pressure before ink ejection of 110 is included.

Referring to FIGS. 1 to 6(c) , the nozzle pressure control device 10 according to an embodiment of the present invention may be connected to at least one inkjet print head 100 . The nozzle pressure control device 10 may include an inkjet print head 100, a light irradiation unit 200, a vision 300, and a controller 400.

Referring again to FIGS. 1 to 4(c) , a plurality of nozzles 110 may be formed in the inkjet print head 100 . The inkjet print head 100 may move in the first direction while being supported by a gantry (not shown). The gantry (not shown) may provide a movement path of the inkjet print head 100 by an area corresponding to the print medium M.

The nozzle 110 may have an ink ejection hole 111 capable of ejecting ink on the print medium M. A plurality of nozzles 110 may be connected to the reservoir 120 .

Referring again to FIGS. 1 to 4(c) , the reservoir 120 may contain ink. The reservoir 120 may supply a certain amount of ink to different nozzles 110 respectively.

Referring back to FIGS. 1 to 4(c) , the light irradiation unit 200 may irradiate light toward the end of the nozzle 110 . The nozzle end means the end of the nozzle 110 at a point where ink is ejected. The light emitter 200 according to an embodiment may emit visible light in an infrared or near infrared region. More specifically, the light irradiation unit 200 may irradiate light having a wavelength of 400 nm or more. The light irradiation unit 200 may irradiate light having a wavelength in the ultraviolet region blocked.

In this case, the ink may be any one or a mixture of acrylic, epoxy, silicone, or rubber-based resins, and preferably may be a UV curable resin curable by UV light or a heat curable resin curable by heat. This is to prevent the ink from being cured by light irradiated from the light irradiation unit 200 when the ink is photocurable ink.

Referring back to FIGS. 1 to 4(c), the vision 300 generates a nozzle end image (hereinafter referred to as 'image') corresponding to the end of the nozzle 110 in a state facing the end of the nozzle 110. can do. The vision 300 may create an image including an image in which ink forms at the end of the nozzle 110 . The vision 300 may extract an image of the end of the nozzle 110 from the image and transmit the image to the controller 400, which will be described later, more specifically, the negative pressure control module 410.

The vision 300 according to an embodiment may be arranged to face the light irradiation unit 200 with the end of the nozzle 110 interposed therebetween.

More specifically, the inkjet print head 100 may include a plurality of nozzles 110 spaced apart at random intervals along the first direction. In this case, the light irradiation unit 200 and the vision 300 may be spaced apart from each other and disposed side by side in the second direction.

Referring back to FIG. 1 , the controller 400 controls the operational relationship between the light irradiation unit 200 and the vision 300, and further adjusts the ink ejection pressure formed inside the nozzle 110 so that the ink and the inkjet print head ( 100), the meniscus pressure can be calculated. The controller 400 may include a negative pressure control module 410, a pressure measurement module 420, a position movement module 430, and an angle adjustment module 440.

The negative pressure control module 410 may be connected to the reservoir 120 . The negative pressure control module 410 may adjust the ink ejection pressure applied to the nozzle 110 . More specifically, the negative pressure control module 410 may adjust the meniscus pressure inside the ink-embedded nozzle 110 before the printing process proceeds.

Referring back to FIGS. 4(a) to 5(c) , the negative pressure control module 410 may automatically or manually calculate an optimal meniscus pressure value based on the image generated by the vision 300.

The negative pressure control module 410 may acquire an appropriate meniscus pressure value by analyzing and reading an image formed on the end of the nozzle 110 in a state where a constant pressure is applied to the nozzle 110 . The negative pressure control module 410 may read an image. The negative pressure control module 410 may read, from the image, a location where light formed by the ink located at the end of the nozzle 110 is focused.

The negative pressure control module 410 may designate the nozzle 110 corresponding to the point where the entire end of the nozzle 110 looks bright as a reference nozzle, and designate a specific pressure value of the reference nozzle as a meniscus pressure value. The negative pressure control module 410 may apply a designated specific pressure value to the nozzle 110 .

The negative pressure control module 410 considers the length and thickness of the pipe, the capacity of the reservoir 120, the number of inkjet print heads 100, MPC type, and material characteristics according to the ink when calculating the specific pressure value. can

The negative pressure control module 410 controls the light irradiation unit 200 and the vision 300 so that the light irradiation unit 200 irradiates light to a specific location and the vision 300 generates an image including the end of the nozzle 110. can be called In addition, the negative pressure control module 410 may adjust the meniscus pressure inside the nozzle 110 with different pressures at the same time or at the same time that the vision 300 generates an image.

The pressure applied to the nozzle 110 and the reservoir 120 by the negative pressure control module 410 may be an arbitrary value less than 0 -98.1 kPa.

The pressure measurement module 420 may measure the pressure generated by the negative pressure control module 410 . The pressure measurement module 420 may measure the applied pressure value adjusted by the negative pressure control module 410 in real time.

The pressure measurement module 420 may provide the meniscus pressure value obtained by the negative pressure control module 410 to a monitor (not shown) or a terminal (not shown) of an operator.

The location movement module 430 may adjust the locations of the light irradiation unit 200 and the vision 300 . The location movement module 430 may individually or simultaneously move the location of the light irradiation unit 200 and the vision 300 .

The location movement module 430 may move the location of the light irradiation unit 200 in the second direction toward the end of the nozzle 110 .

More specifically, the location movement module 430 may move the light irradiation unit 200 and the vision 300 in the second direction. To check and inspect the meniscus pressure of each nozzle 110, the position movement module 430 moves the light irradiation unit 200 and the vision 300 in the second direction, thereby moving the plurality of nozzles 110 formed in the first direction. It may be positioned so as to face the end of the nozzle 110 of the dog. In addition, the location movement module 430 may adjust the separation distance between the light irradiation unit 200 and the vision 300 in the second direction.

The angle adjustment module 440 may adjust an angle between the light irradiation unit 200 and the vision 300 . The angle adjustment module 440 may adjust the angle of the light irradiation unit 200 and the vision 300 individually or simultaneously to form an arbitrary angle with respect to the vertical direction.

The angle adjustment module 440 may adjust an angle formed by the light irradiation unit 200 or an angle formed by the vision 300 in the vertical direction. The angle adjustment module 440 according to an embodiment may independently adjust the inclination of the light irradiation unit 200 and the vision 300 in an angle range of 40 degrees to 80 degrees with respect to the vertical Z-axis.

Referring back to FIG. 2(a) , the inkjet print head 100 may have a plurality of nozzles 110 formed on a gantry (not shown) in a first direction.

In addition, the angle adjustment module 440 includes a nozzle 110 provided in a vertical direction to prevent contamination of the device in advance by some scattered ink falling on the light irradiation unit 200 or the vision 300 while the ink falls in the direction of gravity. ), the light irradiation unit 200 and the vision 300 may be adjusted to be inclined at a predetermined angle.

The angle adjustment module 440 may support and fix the vision 300 at an angle so as to easily grasp the three-dimensional shape of the ink formed on the end of the nozzle 110 .

At this time, the location movement module 430 may adjust the location of the light irradiation unit 200 and the vision 300 in the second direction to set the location values of the light irradiation unit 200 and the vision 300 on specific coordinates with respect to the nozzle 110 . Also, the position movement module 430 may move the light irradiation unit 200 and the vision 300 in the second direction to obtain a nozzle end image of a specific nozzle 110 .

Referring back to FIGS. 6(a) to 6(c), the position movement module 430 and the angle adjustment module 440 direct the light emitted from the light irradiation unit 200 toward the end of the nozzle 110. In order to adjust the position, the position of the light irradiation unit 200 may be changed. Also, the position movement module 430 and the angle adjustment module 440 may adjust the position and angle of the vision 300 to create an image including the end of the nozzle 110 .

A nozzle pressure control method according to the nozzle pressure control device 10 according to an embodiment of the present invention having the above components will be described.

7 is a flowchart showing a nozzle pressure control method according to an embodiment of the present invention.

Referring to FIG. 7 , the nozzle pressure control method according to an embodiment of the present invention includes an ink discharge pressure setting step (S10), an image generating step (S20), and an ink discharge pressure setting step (S30), further comprising a light irradiation unit. And a vision position adjustment step (S00) may be further included.

In the step of adjusting the positions of the light irradiation unit and the vision (S00), the positions of the light irradiation unit and the vision may be adjusted to face each other with the nozzle end interposed therebetween. In step S00 of adjusting the positions of the light emitting unit and the vision, the positions of the light emitting unit and the vision may be adjusted in the first direction or the second direction, and furthermore, the angle of the light emitting unit and the vision may be adjusted to have an arbitrary angle in the vertical direction.

In the ink ejection pressure setting step (S10), the ink ejection pressure applied to the nozzle may be set to a specific value.

In the image generating step (S20), an image of the nozzle end may be generated.

In the ink ejection pressure adjusting step (S30), the ink ejection pressure may be adjusted by determining whether the image is within a predetermined reference range in response to the ink ejection pressure set to a specific value.

To this end, in the step of adjusting the ink ejection pressure (S30), when the image is out of the predetermined reference range, the step of setting the ink ejection pressure (S10) and the step of generating the image (S20) may be repeatedly performed.

In addition, in the ink ejection pressure adjusting step (S30), the ink ejection pressure of a specific value may be determined as the meniscus pressure when the image of the nozzle end matches the specific image.

In the 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 skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

10: nozzle pressure control device
100: inkjet print head 110: nozzle
200: light irradiation unit
300: Vision
400: controller 410: negative pressure control module
420: pressure measurement module 430: position movement module
440: angle adjustment module

Claims (8)

an inkjet print head having nozzles capable of ejecting ink;
a light irradiation unit capable of irradiating light toward the nozzle end;
a vision capable of generating an image of the nozzle end; and
A controller capable of calculating a meniscus pressure optimized for the inkjet print head;
The controller,
a position movement module capable of adjusting a position of the light irradiation unit in a direction perpendicular to the moving direction of the inkjet print head so that the light emitted from the light irradiation unit is directed toward the ink ejection port of the nozzle end;
an angle adjustment module capable of adjusting an angle of the light irradiation unit so that the light emitted from the light irradiation unit is directed toward the ink outlet; and
In the image generated for each nozzle, a nozzle having a point where the light reflected on the ink in the ink outlet appears brightest is selected as a reference nozzle, and the ink ejection pressure applied to the reference nozzle can be designated as a meniscus pressure value. A nozzle pressure control device comprising a negative pressure control module.
According to claim 1,
The vision is arranged to face the light irradiation unit with the nozzle end interposed therebetween, the nozzle pressure control device.
According to claim 1,
The light irradiation unit capable of irradiating visible light in the infrared or near-infrared region, the nozzle pressure control device.
delete delete Setting the ink ejection pressure applied to the nozzle (S10);
generating an image of the nozzle end by irradiating light toward the ink ejection port of the nozzle end (S20); and
In the image generated for each nozzle, the nozzle having the point at which the light condensed in the ink outlet is most likely to be stepped on is selected as a reference nozzle, and the ink ejection pressure applied to the reference nozzle is designated as an optimal meniscus pressure value. , Adjusting the ink ejection pressure (S30), the nozzle pressure control method.
According to claim 6,
In the ink discharge pressure adjustment step (S30),
The nozzle pressure control method of repeating the ink ejection pressure setting step (S10) and the nozzle end image generating step (S20) when the image is out of a predetermined reference range.
According to claim 6,
Before the ink discharge pressure setting step (S10),
and independently adjusting positions and angles of a light irradiation unit facing each other with the nozzle end interposed therebetween so that the irradiated light is focused on the ink in the ink ejection hole (S00). control method.

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