Device for measuring droplet discharge amount, inkjet printing system and method

Abstract

The present disclosure relates to a device for measuring the amount of liquid droplets discharged, an inkjet printing system, and a method for measuring the amount of liquid droplets discharged. The device for measuring the amount of liquid droplets discharged according to an exemplary embodiment may include: a housing provided with an opening, through which liquid droplets discharged from an inkjet head pass, and configured to define an internal space; a liquid droplet receiving component provided in the internal space, for collecting and receiving liquid droplets passing through the opening; a weight measuring component configured to measure the weight of liquid droplets received in the liquid droplet receiving component; and a moving component configured to move the liquid droplet receiving component in a first direction. The device for measuring the amount of liquid droplets discharged, the inkjet printing system, and the method for measuring the amount of liquid droplets discharged can accurately measure the amount of liquid droplets discharged from the inkjet head.

Description

Technical Field

[0001] The present disclosure relates to a device for measuring the amount of liquid droplets discharged, an inkjet printing system, and a method for measuring the amount of liquid droplets discharged, and more particularly, to a device, an inkjet printing system, and a method for measuring the amount of liquid droplets discharged from an inkjet head that can accurately measure the amount of liquid droplets discharged. Background Art

[0002] Recently, inkjet printing methods that eject liquid ink in the form of droplets onto a surface to be printed have been used in various solution processes in the semiconductor and display fields. In order for inkjet printing devices to be applied to practical industrial purposes, they must discharge a precise number of ink droplets to multiple nozzle heads, thereby forming precise and high-resolution patterns and printing ultra-thin films.

[0003] The amount of inkjet droplets discharged is easily affected by the atmosphere, temperature, humidity, air flow changes, etc. around the inkjet head, so even if the same inkjet head is used, the amount of discharged droplets may exceed the set range. Therefore, in order to accurately control the amount of ink droplets to be discharged, it is necessary to accurately measure the amount of droplets discharged from the inkjet head.

[0004] Generally, the amount of droplets discharged can be confirmed by measuring the weight of droplets discharged from the inkjet head and collected. However, since the airflow generated in the space between the nozzle surface of the inkjet head and the droplet receiving part may not be able to accommodate all the discharged droplets, and some droplets may be scattered, there is a limitation that it is difficult to accurately measure the weight of the amount of droplets discharged. In order to solve this limitation, a method of suppressing the generation of airflow using a shell surrounding the droplet receiving part has been tried, but it still cannot effectively eliminate the dispersion of droplets.

[0005] Therefore, there is an increasing demand for a technology capable of measuring the exact amount of liquid droplets discharged from an inkjet head without dispersing part of the liquid droplets.

[0006] [Prior art literature]

[0007] [Patent Document]

[0008] (Patent Document 1) Korean Patent Publication No. 10-2020-0048941 Summary of the invention

[0009] The present disclosure provides an apparatus for measuring a liquid droplet discharge amount, which is capable of accurately measuring the discharge amount of liquid droplets, an inkjet printing system, and a method for measuring a liquid droplet discharge amount.

[0010] The present disclosure also provides an apparatus for measuring a liquid droplet discharge amount, which can reduce the generation of airflow and suppress contamination of an inkjet head when measuring the liquid droplet discharge amount, an inkjet printing system, and a method for measuring the liquid droplet discharge amount.

[0011] According to an exemplary embodiment, an apparatus for measuring a droplet discharge amount includes: a shell provided with an opening, through which droplets discharged from an inkjet head pass, and the shell is configured to define an internal space; a droplet holding component provided in the internal space to collect and hold droplets passing through the opening; a weight measuring component configured to measure the weight of droplets held in the droplet holding component; and a moving component configured to move the droplet holding component in a first direction.

[0012] The droplet receiving member may be configured to collect and receive droplets while moving in the first direction.

[0013] The droplet receiving member may be configured to collect and receive the droplets while moving in a portion shorter than a length of the opening in the first direction.

[0014] The housing may include: a base; a wall connected to the base to surround the internal space; and a cover connected to an upper end of the wall and having an opening, wherein the device may further include a shutter that slides parallel to the cover to open or close the opening.

[0015] The height of the top surface of the shutter may be partially lower than or equal to the height of the top surface of the cover, and may be partially higher than or equal to the height of the bottom surface of the cover.

[0016] The shutter may include a stepped portion extending in a direction intersecting the sliding direction.

[0017] The droplet holding part may include: a wall configured to provide a holding space for holding the droplet; a protrusion provided at a central portion of the holding part; and a groove provided between the wall and the protrusion and extending along the wall, wherein the inkjet head may be provided on the protrusion to discharge the droplet.

[0018] The weight measuring member may be provided in the internal space to move in the first direction together with the droplet receiving member, and the device may further include an elastic holding member configured to hold the weight measuring member so that vibration generated during the movement is offset.

[0019] The inkjet head may be configured to discharge liquid droplets in a stationary state.

[0020] According to another exemplary embodiment, an inkjet printing system includes: a substrate holder provided on a first area to hold a substrate; an inkjet head configured to discharge droplets onto the substrate to provide a coating; an apparatus for measuring the amount of droplet discharge according to the above-mentioned method, provided on a second area separated from the first area; and an inkjet head transport component configured to move the inkjet head between the first area and the second area in a second direction intersecting the first direction.

[0021] The substrate holder may include a substrate transfer member configured to move the substrate in a first direction when the inkjet head discharges droplets onto the substrate.

[0022] The inkjet printing system may further include a controller configured to control a discharge amount or a discharge rate of droplets discharged from the inkjet head toward the substrate using the droplet discharge amount measured in the device for measuring the droplet discharge amount.

[0023] According to another exemplary embodiment, a method for measuring a droplet discharge amount includes: providing an inkjet head at a droplet discharge amount measurement position; collecting droplets at the droplet discharge amount measurement position to provide the droplets to a droplet holding component for holding the droplets; moving the droplet holding component in a first direction; and discharging droplets toward the moved droplet holding component through the inkjet head.

[0024] A droplet receiving member may be provided in an inner space of a housing formed with an opening through which droplets discharged from the inkjet head pass, and when the droplet receiving member moves, the droplet receiving member may move in a portion shorter than a length of the opening in the first direction.

[0025] When liquid droplets are discharged, the inkjet head may discharge the liquid droplets onto a protrusion provided at a central portion of the liquid droplet receiving member.

[0026] When liquid droplets are discharged, the inkjet head may discharge the liquid droplets in a state of being fixed at a liquid droplet discharge amount measurement position. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Exemplary embodiments may be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:

[0028] Figure 1 is a view showing a configuration of an apparatus for measuring a droplet discharge amount according to an exemplary embodiment;

[0029] Figure 2 is a cross-sectional view of a droplet receiving member according to an exemplary embodiment;

[0030] Figure 3 is a view showing a configuration of an inkjet printing system according to another exemplary embodiment; and

[0031] Figure 4is a flowchart illustrating a method for measuring a droplet discharge amount according to another exemplary embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, specific embodiments will be described in more detail with reference to the accompanying drawings. However, the present invention can be embodied in different forms and should not be construed as being limited to the embodiments described herein. On the contrary, these embodiments are provided to make the present disclosure comprehensive and complete and to fully convey the scope of the present invention to those skilled in the art. In the description, the same elements are represented by the same reference numerals. In the figures, the sizes of layers and regions are exaggerated for clarity. The same reference numerals refer to the same elements throughout the text.

[0033] Figure 1 is a view showing a configuration of an apparatus for measuring a droplet discharge amount according to an exemplary embodiment, and Figure 2 is a cross-sectional view of a droplet receiving component according to an exemplary embodiment.

[0034] Reference Figure 1 and Figure 2 According to an exemplary embodiment, an apparatus 100 for measuring a droplet discharge amount may include: a shell provided with an opening 114, through which droplets D discharged from an inkjet head 200 pass, the shell being configured to define an internal space; a droplet holding component 120 provided in the internal space to collect and hold droplets passing through the opening 114; a weight measuring component 130 configured to measure the weight of droplets held in the droplet holding component 120; and a moving component 140 configured to move the droplet holding component 120 in a first direction.

[0035] The inkjet head 200 may be provided to discharge liquid droplets D onto a substrate when performing an inkjet printing process, and a plurality of nozzles may be arranged on a bottom surface facing the substrate.

[0036] The housing 110 may be configured to define a stable internal space separated from the external space so that the falling of the discharged droplets is not affected by the external atmosphere, such as when the droplets discharged from the inkjet head 200 are dispersed by airflow or the like and cannot fall directly downward. The top surface of the housing 110 is provided with an opening 114 so that the droplets D discharged from the inkjet head 200 enter the internal space through the opening 114 so as to fall into the internal space.

[0037] The droplet holding part 120 is provided in the inner space of the housing 110 to collect and hold the droplets falling through the opening 114. The upper portion of the droplet holding part 120 may have an open structure so as to collect the falling droplets, and the upper portion of the droplet holding part 120 having the open structure may be provided to face the opening 114. Since the outer space and the adjacent space of the opening 114 are affected by the external atmosphere, the droplet holding part 120 may be entered from the inner space of the housing 110 to allow the discharged droplets to fall into the droplet holding part 120 without being dispersed by the vortex of the air.

[0038] The weight measuring part 130 may measure the weight of the liquid droplets discharged and then contained in the liquid droplet containing part 120. The weight measuring part 130 is provided to be connected to the liquid droplet containing part 120 whose weight is known, so that after measuring the weight of the liquid droplet containing part 120 containing the liquid droplets, the weight of only the contained liquid droplets is measured by subtracting the weight of only the liquid droplet containing part 120. Since the weight measuring part 130 needs to be connected to the liquid droplet containing part 120 to measure the weight of the liquid droplets, the weight measuring part 130 may also be provided in the internal space of the housing 110 so as to stably measure the weight of the liquid droplets without being affected by the external atmosphere. The weight measuring part 130 needs to be able to measure the weight of even a small amount of liquid droplets discharged from the inkjet head 200, and therefore, the weight measuring part 130 may be an electronic scale capable of ultra-precise measurement.

[0039] The moving part 140 may move the droplet holding part 120 in the first direction. The moving part 140 may include a linear guide extending in the first direction and a motor providing a driving force to move the droplet holding part 120 along the linear guide. The moving part 140 may be configured to move the droplet holding part 120 in the first direction, but the present embodiment is not particularly limited to a specific method or mechanism.

[0040] The moving part 140 can also move the droplet holding part 120 together with the housing 110 by moving the housing 110 that holds the droplet holding part 120. Here, in order to measure the weight of the droplet, the droplet holding part 120 that holds the droplet needs to be connected to the weight measuring part 130, so the droplet holding part 120 can be connected to the weight measuring part 130 while being held in the internal space, and the weight measuring part 130 can be connected to the housing 110, so the droplet holding part 120 can be stably held on the housing 110 by the weight measuring part 130 without interfering with the weight measurement.

[0041] The moving part 140 may be provided in the internal space of the fixed housing 110 to move the droplet receiving part 120 and the weight measuring part 130. However, in order for the moving part 140 to be accommodated in the internal space of the housing 110, the size of the housing 110 must be increased, and since the operation of the moving part 140 may cause airflow changes or heat generation in the internal space of the housing 110, a partition structure may also be required to accommodate the moving part 140 in the internal space.

[0042] The liquid droplet receiving member 120 may collect and receive liquid droplets discharged from the inkjet head 200 while being moved in the first direction by the moving member 140 .

[0043] When various types of patterns are formed using an inkjet printing system, the inkjet head 200 may discharge ink droplets while being fixed at a printing position, and when a substrate provided below the inkjet head 200 moves, the discharged droplets may settle on the surface of the substrate to form a functional coating film. When the inkjet head 200 discharges droplets in a state where a droplet holding part is fixed to measure the amount of droplet discharge, the atmosphere and conditions under which the inkjet head 200 discharges droplets to a moving substrate during actual inkjet printing may be different. The amount of droplet discharge may be easily affected by the atmosphere around the inkjet head, airflow changes, etc., and therefore, even if the droplet discharge amount is measured using a fixed droplet holding part, it may be different from the amount of droplets discharged onto a moving substrate during actual inkjet printing.

[0044] In the process of discharging ink droplets from the inkjet head 200 by the discharge pressure, the state of the droplets (e.g., the size of the droplets, the speed of the droplets, the change in the atmospheric pressure around the droplets, etc.) may be changed not only by the discharge pressure, but also by the change in the airflow and vortex generated by the relative movement of the inkjet head 200 and the substrate or the droplet holding part 120 provided below. Even if the relative speed of the inkjet head and the substrate or the droplet holding part 120 is not very large, the droplets discharged by the discharge pressure may cause the atmospheric pressure of the space between the inkjet head and the substrate or the droplet holding part 120 to change, thereby generating airflow changes and vortexes between the inkjet head and the substrate or the droplet holding part 120. In addition, when the inkjet head discharges droplets by the discharge pressure, in addition to the main droplets, fine secondary droplets may be generated. The generation of secondary droplets may be promoted by the change in airflow or vortexes generated between the inkjet head 200 and the substrate (or the droplet holding part 120), and the secondary droplets may be more easily dispersed along the airflow. For both primary droplets and secondary droplets, if the amount or speed of the airflow or vortex increases, the droplets may not fall at a precise landing point or may be scattered around.

[0045] Furthermore, if an eddy current is generated between the inkjet head 200 and the substrate (or the droplet receiving part 120), the droplets dispersed along the eddy current may be introduced to the bottom surface of the inkjet head 200, thereby contaminating the bottom surface of the nozzle part provided with the inkjet head 200. If the bottom surface of the inkjet head 200 is contaminated and at least a portion of the nozzle part provided on the bottom surface of the inkjet head 200 is clogged or the flow of discharged droplets is obstructed, it may be difficult to accurately discharge or drop the droplets, resulting in a decrease in the quality of inkjet printing.

[0046] The change in airflow and generation of vortices caused by the movement of a structure (such as a substrate or a droplet holding component) provided below the inkjet head, the resulting change in the weight of falling droplets, and the contamination of the bottom surface of the inkjet head can be confirmed by conducting actual experiments and airflow analysis using inkjet heads having various nozzle structures and arrangements. To address this limitation, in the present disclosure, the droplet holding component 120 can collect and hold droplets discharged from the inkjet head 200 while moving in a first direction.

[0047] Since the droplet holding member 120 collects the droplets discharged from the inkjet head 200 while moving in the first direction, the condition in which the droplets discharged from the inkjet head fall on the moving substrate during the actual inkjet printing process can be very closely simulated, and the actual droplet discharge amount can be more accurately measured in the environment in which the actual inkjet printing process is performed. In addition, as the droplet holding member 120 moves while collecting and holding the discharged droplets, the droplets dispersed along the vortex between the inkjet head 200 and the droplet holding member 120 can be effectively prevented from contaminating the bottom surface of the inkjet head 200.

[0048] Furthermore, in order to measure the amount of liquid droplet discharge in the apparatus 100 according to one exemplary embodiment, the inkjet head 200 may discharge liquid droplets in a fixed state.

[0049] In order to drop ink droplets onto a moving substrate in an inkjet printing system, the inkjet head may be fixed at a printing position to discharge ink droplets. Therefore, in order to accurately simulate an actual ink droplet discharge state, the inkjet head 200 that discharges ink droplets onto a droplet receiving member of the device 100 may discharge droplets in a fixed state.

[0050] The droplet receiving part 120 may collect and receive the droplets while moving a portion shorter than the length of the opening 114 in the first direction.

[0051] In order to collect and contain liquid droplets falling through the opening 114 without being disturbed by the surrounding configuration of the housing 110 , the liquid droplet containing member 120 may be disposed to be aligned with a central portion of the opening 114 .

[0052] Since the inkjet head 200 discharges liquid droplets in a fixed state, if the portion of the liquid drop holding part 120 that moves in the first direction is longer than or equal to the length of the opening 114 in the first direction, the inkjet head 200 may not be arranged on the opening 114, but may be arranged on the cover 113 around the opening 114. Therefore, the liquid droplets discharged from the inkjet head 200 may not fall through the opening 114, and the movement of the liquid droplets may be directly disturbed by the cover 113, or the flow of gas may be changed by the cover 113 to indirectly disturb the movement of the liquid droplets. The liquid drop holding part 120 can effectively collect and hold the falling liquid droplets while moving a portion shorter than the length of the opening 114 in the first direction without disturbing the movement. Considering the discharge angle of the inkjet head 200 and the interference of the cover 113 with the air flow, the portion corresponding to about 80% of the length of the opening 114 in the first direction may be moved. The droplet holding component 120 can collect droplets while reciprocating in the first direction when the inkjet head 200 is arranged in the central part of the opening 114, and can collect droplets while scanning along the first direction when the inkjet head 200 is arranged on one side of the opening 114.

[0053] The housing 110 may include a base 111, a wall 112 connected to the base 111 to surround an internal space, and a cover 113 connected to an upper end of the wall 112 and having an opening 114. The base 111, the wall 112, and the cover may define an internal space separated from an external space while minimizing the influence of the external environment.

[0054] The opening 114 provided in the cover 113 may be a necessary component for providing a space for the discharged liquid droplets to reach the liquid droplet receiving part 120. However, after the liquid droplets are collected and received in the liquid droplet receiving part 120, an external air flow may be introduced through the opening 114, thereby affecting the weight measurement accuracy of the weight measurement part 130, which must be able to measure even a small amount of droplet weight change when measuring the weight of the received liquid droplets.

[0055] The apparatus 100 for measuring the amount of liquid droplet discharge may further include a shutter 150 that slides parallel to the cover 113 to open or close the opening 114. The shutter 150 may slide by a shutter moving member 151 that linearly moves the shutter 150 parallel to the cover 113 (eg, horizontally).

[0056] The shutter 150 may open the opening 114 when collecting and containing droplets, so that the droplets fall into the droplet holding part 120. In addition, when the weight of the droplets is measured after the droplets are contained in the droplet holding part 120, the shutter 150 may close the opening 114 to prevent the external airflow from being introduced, thereby isolating the internal space of the housing 110 from the external environment, and thus, the weight of the droplets can be accurately measured. When the opening 114 is opened, the shutter 150 may be retracted and at least partially arranged below (or above) the cover 113 so as not to interfere with the falling of the droplets. In addition, when the opening 114 is closed, the shutter 150 may slide parallel to the cover 113 to close the opening 114 while crossing the droplet discharge direction with the shortest distance, thereby minimizing the change of the airflow around the opening 114 and the dispersion of the droplets caused thereby in the process of the shutter 150 closing the opening, thereby inducing the droplets to fall effectively and blocking the introduction of the external airflow.

[0057] In order to minimize mechanical interference with surrounding components (e.g., the cover 113, etc.) and changes in air flow that may occur when the shutter 150 that opens or closes the droplet holding part 120 moves between the inkjet head 200 and the droplet holding part 120, there may be a restriction on reducing the gap between the inkjet head 200 and the droplet holding part 120. In addition, a meniscus may be defined downward from the inkjet head 200, and a meniscus may be defined upward from the droplet holding part 120 due to the surface tension of the ink droplets, and when interference between ink droplets protruding from the bottom surface of the inkjet head 200 and the top surface of the droplet holding part 120 and the shutter 150 is considered, the gap between the inkjet head 200 and the droplet holding part 120 may be further increased.

[0058] In order to prevent the droplets discharged from the inkjet head 200 from dispersing and being discharged to the outside of the droplet holding part 120, and to prevent contamination of the bottom surface of the inkjet head 200 due to vortexes, it is necessary to minimize the gap between the inkjet head 200 and the droplet holding part 120 within a range that does not interfere with the surrounding components or the curved liquid surface of the ink droplets.

[0059] When the shutter 150 having an integral flat plate structure slides along the top or bottom surface of the cover 113 to open or close the opening 114, the gap between the inkjet head 200 and the droplet holding part 120 needs to be at least greater than the sum of the thickness of the cover 113 and the thickness of the shutter 150 to eliminate mechanical interference.

[0060] To address this structural limitation, the height of the top surface of the shutter 150 may be partially lower than or equal to the height of the top surface of the cover 113, and may be higher than or equal to the height of the bottom surface of the cover 113. In addition, the shutter 150 may include a stepped portion extending in a direction intersecting the sliding direction.

[0061] In the case where the shutter 150 having an integral flat plate structure slides along the bottom surface of the cover 113, the height of the top surface of the shutter 150 may not be lower than the height of the top surface of the cover 113, and therefore, there is a limitation in minimizing the gap between the inkjet head 200 and the droplet receiving part 120. However, when the shutter 150 includes a step portion extending in a direction intersecting the sliding direction, and a front portion and a rear portion provided on both sides with respect to the center of the step portion, the gap between the inkjet head 200 and the droplet receiving part 120 can be reduced by a distance equivalent to the height of the step portion. That is, due to the step portion, the top surface of the front portion of the shutter 150 can be higher than the top surface of the rear portion of the shutter 150, and the height of the top surface of the front portion of the shutter 150 can be lower than or equal to the height of the top surface of the cover 113, and higher than or equal to the height of the bottom surface of the cover 113.

[0062] When the shutter 150 is in the closed position, the shutter 150 can move forward so that the shutter 150 closes the opening 114, and when the shutter 150 is in the open position, the shutter 150 can move backward so that the rear portion of the shutter 150 is arranged under the cover 113, and the front portion of the shutter 150 moves laterally from the opening 114 so that at least a portion of the opening 114 is closed.

[0063] Since the shutter 150 opens or closes the opening 114 while sliding in parallel with the cover 113, when the shutter 150 is in the open position, the opening 114 may be surrounded by the cover 113 and the front portion of the shutter 150. If there is a difference between the height of the top surface of the cover 113 covering the opening 114 and the height of the top surface of the shutter 150, airflow changes or vortices may occur due to the height difference around the opening 114. However, the height of the top surface of the front portion of the shutter 150 may be lower than or equal to the height of the top surface of the cover 113, and higher than or equal to the height of the bottom surface of the cover 113, thereby minimizing airflow changes and vortices. If the top surface of the front portion of the shutter 150 is flush with the top surface of the cover 113, it may be more effective in controlling airflow changes.

[0064] The droplet holding component 120 includes a wall 121 providing a holding space for holding droplets, a protrusion 122 provided in the central portion of the holding space, and a groove 123 provided between the wall 121 and the protrusion 122 and extending along the wall 121. The inkjet head 200 can be configured to discharge droplets D on the protrusion 122.

[0065] A general droplet receiving part may be a simple container consisting of a wall and a bottom that provide a droplet receiving space. However, the top surface of the inkjet head and the bottom that is the falling surface must be greater than the height of the wall. In the case of a general droplet receiving part, the distance between the inkjet head and the falling surface (i.e., the top surface of the bottom) is large, so not only is the drop rate at the falling position low, but also the discharged and falling droplets are scattered, making it difficult to accurately measure the droplet discharge amount, and the inkjet head and the like may be contaminated by the scattered droplets.

[0066] In the present disclosure, the inkjet head 200 may be configured to be arranged on the protrusion 122 provided in the central portion of the accommodation space defined by the wall 121 to discharge the droplet D, and therefore, the falling surface on which the droplet falls may be defined on the top surface of the protrusion 122 that protrudes more than the surrounding area to reduce the gap between the inkjet head 200 and the protrusion 122, thereby increasing the falling rate of falling at the correct position. When the droplet D discharged from the inkjet head 200 falls on the top surface of the protrusion 122, not only can the distance that the discharged droplet falls be reduced, but also by providing the coating L due to surface tension or interface phenomenon, the dispersion of the droplet can be effectively prevented.

[0067] The coating L provided on the top surface of the protrusion 122 may flow down under the action of gravity over time and be collected in the groove 123, so the weight measuring part 130 can stably and accurately measure the weight of the droplet. The top surface of the protrusion 122 may be flat, or may be provided as a curved surface in which the central portion protrudes higher than the periphery, so that the coating L provided by the droplet can flow down easily, prevent the droplet from being scattered, and stably collect and hold the droplet.

[0068] The height of the droplet receiving part 120 may be determined to avoid interference with the sliding shutter 150. In order to suppress mechanical interference by making the highest height of the droplet receiving part 120 lower than the bottom surface of the shutter 150 and minimize the gap between the inkjet head 200 and the falling surface, the top surface of the protrusion 122 may be higher than or equal to the top surface of the wall 121.

[0069] The weight measuring component 130 may be configured to be provided in the internal space of the housing 110 to move in the first direction together with the droplet receiving component 120, and the device 100 for measuring the droplet discharge amount according to an exemplary embodiment may also include an elastic retaining component 160, which retains the weight measuring component 130 to offset the vibration generated when the weight measuring component 130 moves.

[0070] If the weight measuring part 130 (e.g., an electronic scale) is arranged in an open space, it may be affected by the surrounding environment (e.g., external airflow), so it is difficult to accurately measure the amount of liquid droplet discharge. When the liquid droplets stably fall and are collected in the liquid droplet receiving part 120, and the weight of the liquid droplets received in the liquid droplet receiving part 120 is measured, the weight measuring part 130 may be provided in the internal space of the housing 110 together with the liquid droplet receiving part 120, and the internal space is isolated from the external environment by using the shutter 150, so that the weight of the liquid droplets can be accurately measured without being affected by the surrounding environment. Since the liquid droplet receiving part 120 moves in the first direction, the weight measuring part 130 connected to the liquid droplet receiving part 120 to measure the weight of the liquid droplets may also move in the first direction together with the liquid droplet receiving part 120. The moving part 140 may move the housing 110 that receives the liquid droplet receiving part 120 and the weight measuring part 130 in the internal space in the first direction to allow the liquid droplet receiving part 120 and the weight measuring part 130 to move simultaneously without complicated equipment.

[0071] Since the weight measuring part 130 requires high precision to accurately measure the weight of even a small amount of liquid droplets, it is necessary to offset the vibration generated when the weight measuring part 130 moves when measuring the weight of the liquid droplets so that it is not transmitted to the weight measuring part 130. The weight measuring part 130 may be configured to be provided on the base 111 of the housing 110. If an elastic holding part 160 is provided between the lower portion of the weight measuring part 130 and the base 111, the vibration generated during the movement can be effectively offset due to the elasticity of the elastic holding part 160, and the weight measuring part can also be stably held on the base 111. The elastic holding part 160 may include a first connection part and a second connection part connected to the base 111 and the lower portion of the weight measuring part 130, respectively, and an elastic member such as rubber or a spring interposed between the first connection part and the second connection part.

[0072] The droplet holding part 120 may be configured to be provided on the weight measuring part 130 to measure the weight of the droplet. After measuring the weight of the droplet, the droplet holding part 120 may be detachably connected to the weight measuring part 130 to remove or clean the held droplet. When the droplet holding part is attached to the weight measuring part 130 again after being detached, the droplet holding part must be attached to the same fixed position in order to effectively collect and hold the discharged droplets and accurately measure the weight of the droplets. For this purpose, the mounting position determining part 125 may be configured to be provided at the lower part of the droplet holding part 120. The droplet holding part 120 may be simply mounted at a fixed position on the droplet holding part holder 131 of the weight measuring part 130 relative to the mounting position determining part 125. The mounting position determining part 125 does not need to have a protruding form and may have various forms such as a recess or a groove.

[0073] Figure 3 is a view showing a configuration of an inkjet printing system according to another exemplary embodiment.

[0074] In describing an inkjet printing system according to another exemplary embodiment, details overlapping with the previously described apparatus for measuring a droplet discharge amount according to an exemplary embodiment will be omitted.

[0075] Reference Figure 3 According to another exemplary embodiment, an inkjet printing system may include a substrate holder 300 configured to be provided on a first area to hold a substrate S, an inkjet head 200 that discharges droplets onto the substrate S to form a coating layer, an apparatus 100 for measuring a droplet discharge amount according to an exemplary embodiment, the apparatus 100 is configured to be provided on a second area separated from the first area, and an inkjet head transport component 400 that moves the inkjet head 200 between the first area and the second area along a second direction intersecting the first direction.

[0076] The inkjet printing system may discharge a solution state of functional ink including liquid crystal, transparent resin (OCR), etc. on a substrate such as a panel or a film through a plurality of nozzle parts provided on the inkjet head 200 to form various types of coatings or pattern layers.

[0077] The substrate holder 300 may be configured to be provided on a first area, which is a printing area where a printing process is performed, to hold the substrate S as a printing target.

[0078] The inkjet head 200 may be configured to provide a plurality of nozzle parts through which liquid droplets are discharged, so as to form a coating layer by discharging the liquid droplets toward the substrate S.

[0079] The device 100 for measuring the droplet discharge amount can be configured to be provided on a second area (or peripheral area) separated from the first area (i.e., the printing area), so that when it is necessary to check the droplet discharge amount before or during the printing process, the droplet discharge amount can be measured by measuring the weight of the droplets discharged from the inkjet head 200.

[0080] The apparatus 100 for measuring the amount of droplet discharge may include a housing configured to provide an opening 114 and configured to define an internal space, droplets discharged from the inkjet head 200 passing through the opening, a droplet holding member 120 configured to be provided in the internal space to collect and hold droplets passing through the opening 114, a weight measuring member 130 configured to measure the weight of droplets held in the droplet holding member 120, and a moving member 140 configured to move the droplet holding member 120 in a first direction.

[0081] The inkjet head 200 may discharge ink droplets onto a substrate provided in a first area (i.e., a printing area) during a printing process, and may discharge ink droplets onto a droplet receiving member 120 provided in a second area (i.e., a peripheral area) during a process of measuring a droplet discharge amount. That is, the inkjet head 200 may move between the first area and the second area along a second direction intersecting the first direction, depending on whether a printing process or a process of measuring a droplet discharge amount is performed.

[0082] In the case of a large-area substrate, it is difficult to manufacture an inkjet head including a plurality of nozzle parts corresponding to the substrate area and define a workspace capable of performing inkjet printing by ejecting ink through the plurality of nozzle parts, which requires a large chamber and is very troublesome in many aspects. The plurality of nozzle parts provided in the inkjet head 200 may be linearly arranged along the second direction, and the substrate holder 300 holding the inkjet head 200 or the substrate S may be moved in a first direction intersecting the second direction to form a uniform coating on the large-area substrate. Moving the substrate holder 300 may be more stable than moving the inkjet head 200 having a complex structure and having to accurately eject ink droplets having a set ejection amount.

[0083] Therefore, the substrate holder 300 may include a substrate transport part 310 that moves the substrate S in the first direction when the inkjet head 200 discharges droplets to the substrate S. The substrate transport part 310 may include a linear guide extending in the first direction and a motor that provides a driving force to move the substrate S along the linear guide. The substrate transport part 310 may be configured to move the substrate S in the first direction, but the present embodiment is not particularly limited to a specific method or mechanism. Generally, since the substrate S has a rectangular shape, the substrate may be moved in the first direction after aligning the long side of the rectangular shape with a direction parallel to the first direction. The inkjet head transport part 400 may move the inkjet head 200 in the second direction to expand the printing area width in the second direction and fix the inkjet head 200, and then move the substrate S again in the first direction while discharging droplets using a plurality of nozzle parts provided in the inkjet head 200.

[0084] In the inkjet printing system, the inkjet head 200 may be fixed, and inkjet printing may be performed while the substrate S moves in the first direction. As a result, since the droplet holding part 120 collects droplets discharged from the inkjet head 200 while moving in the first direction, the condition in which the droplets discharged from the inkjet head fall on the moving substrate during the actual inkjet printing process may be very closely simulated, and the actual droplet discharge amount may be more accurately measured in an environment in which the actual inkjet printing process is performed. In addition, since the mobile droplet holding part 120 collects and holds the discharged droplets, the bottom surface of the inkjet head 200 may be effectively prevented from being contaminated by droplets dispersed along the eddy current generated between the inkjet head 200 and the droplet holding part 120, and since the actual inkjet printing process is performed using the uncontaminated inkjet head 200 during the measurement of the droplet discharge amount, inkjet printing may be accurately performed.

[0085] The inkjet printing system according to another exemplary embodiment may further include a controller 500 that controls a discharge amount or a discharge speed of droplets discharged from the inkjet head 200 onto the substrate S using the droplet discharge amount measured by the apparatus 100 .

[0086] In the process of discharging ink droplets from the inkjet head 200 by the discharge pressure, the state of the droplets (e.g., the size of the droplets, the speed of the droplets, the change in the atmospheric pressure around the droplets, etc.) may be affected not only by the discharge pressure but also by the change in the airflow and vortex generated according to the relative movement of the inkjet head 200 and the substrate or droplet receiving part 120 provided below. In addition, if the bottom surface of the inkjet head 200 is contaminated, at least a portion of the nozzle part provided on the bottom surface of the inkjet head 200 may be clogged or the flow of the discharged droplets may be hindered, so it is difficult to accurately discharge or drop the droplets.

[0087] In an inkjet printing system according to another exemplary embodiment, before inkjet printing is performed on a substrate S as a printing target, or while inkjet printing is being performed, the amount of droplets discharged by the inkjet head 200 can be measured in real time in a state or atmosphere where inkjet printing is being performed, and if necessary, the controller 500 can control the amount of droplets discharged by the inkjet head 200 toward the substrate S or the speed of droplet discharge based on the measured amount of droplet discharge to perform an actual inkjet printing process. As a result, the inkjet printing quality can be further improved by accurately and precisely controlling the amount of droplet discharge that can be changed according to the surrounding atmosphere or droplet conditions in real time.

[0088] Figure 4 is a flowchart illustrating a method for measuring a droplet discharge amount according to another exemplary embodiment.

[0089] In explaining a method for measuring a liquid droplet discharge amount according to another exemplary embodiment, details overlapping with those previously described with respect to a liquid droplet discharge amount measuring apparatus or an inkjet printing system according to one exemplary embodiment will be omitted.

[0090] Reference Figure 4 According to another exemplary embodiment, a method for measuring a droplet discharge amount may include a process S100 of providing an inkjet head 200 at a droplet discharge amount measurement position, a process S200 of providing a droplet holding part 120 to collect and hold droplets at the droplet discharge amount measurement position, a process S300 of moving the droplet holding part 120 in a first direction, and a process S400 of discharging droplets on the moved droplet holding part 120 through the inkjet head 200.

[0091] Each process of the method for measuring a droplet discharge amount according to another exemplary embodiment does not necessarily have to be performed in time sequence, and each process may be performed in reverse order or simultaneously as necessary.

[0092] First, the inkjet head 200 is provided at a droplet discharge amount measurement position (process S100). In the inkjet printing apparatus, the inkjet head 200 may be provided at a predetermined droplet discharge amount measurement position, which is arranged on a peripheral area (second area) separated from a printing area (first area) where actual inkjet printing is performed on the substrate S.

[0093] Next, a droplet receiving part 120 may be provided to collect and receive droplets at the droplet discharge amount measurement position (process S200). The droplet receiving part 120 may be provided at the lower portion of the inkjet head 200, which is arranged at the droplet discharge amount measurement position, so that droplets discharged from the inkjet head 200 fall onto the droplet receiving part 120 to be collected and received.

[0094] In addition, the droplet receiving member 120 may be moved in the first direction (process S300). In order to simulate the droplet discharge environment such as the movement of the substrate S as the printing target and the airflow generated thereby during the inkjet printing process, in the method for measuring the droplet discharge amount, in the same or similar manner, the droplet receiving member 120 as the drop target of the inkjet head 200 may be moved in the first direction.

[0095] Finally, the inkjet head 200 may discharge droplets toward the moving droplet receiving member 120 (process S400). The process S300 of moving the droplet receiving member and the process S400 of discharging droplets may be performed simultaneously, or the process S300 of moving the droplet receiving member may be started first and performed while the process S400 of discharging droplets is performed.

[0096] Since the inkjet head 200 discharges the liquid droplets toward the liquid drop holding member 120 moving in the first direction, the actual liquid drop discharge amount can be more accurately measured in an environment where an actual inkjet printing process is performed. In addition, when the discharged liquid droplets are collected and held, the liquid drop holding member 120 moves, which can effectively prevent the liquid droplets dispersed along the eddy current between the inkjet head 200 and the liquid drop holding member 120 from contaminating the bottom surface of the inkjet head 200.

[0097] The droplet holding component 120 may be provided in the internal space of the shell 110, in which an opening 114 is provided, through which droplets discharged from the inkjet head 200 pass, and in the process S300 of moving the droplet holding component 120, the droplet holding component 120 may move in a portion shorter than the length of the opening 114 in the first direction.

[0098] When the droplet holding member 120 moves in a portion shorter than the length of the opening 114 in the first direction, the falling droplets can be effectively collected and held without interfering with the movement. For example, in consideration of the discharge angle of the inkjet head 200 and the interference of the cover 113 with the air flow, a portion corresponding to about 80% of the length of the opening 114 in the first direction can be moved. The droplet holding member 120 can reciprocate in the first direction in a state where the inkjet head 200 is arranged at the central portion of the opening 114, and the droplet holding member can perform scanning in the first direction in a state where the inkjet head 200 is arranged at one side of the opening 114.

[0099] In the process S400 of discharging liquid droplets, the inkjet head 200 may discharge liquid droplets toward the protrusion 122 provided at the central portion of the liquid drop receiving part 120 .

[0100] The inkjet head 200 may discharge the droplet D toward the protrusion 122 provided at the central portion of the droplet receiving part, and thus, a falling surface on which the droplet falls may be formed on the top surface of the protrusion 122 protruding more than the surrounding area to reduce the gap between the inkjet head 200 and the protrusion 122, thereby increasing the falling rate of falling at the correct position. When the droplet D discharged from the inkjet head 200 falls on the top surface of the protrusion 122, not only the distance that the discharged droplet falls may be reduced, but also the droplet may be effectively prevented from being scattered by the coating layer L provided due to surface tension or interface phenomenon.

[0101] In the process S400 of discharging liquid droplets, the inkjet head 200 may discharge liquid droplets in a state of being fixed at a liquid droplet discharge amount measurement position.

[0102] In order to drop ink droplets onto a moving substrate in an inkjet printing system, the inkjet head may be fixed at a printing position to discharge ink droplets. Therefore, in order to accurately simulate an actual ink droplet discharge state, the inkjet head 200 that discharges ink droplets to a droplet receiving part of the device 100 to measure the droplet discharge amount may discharge droplets in a fixed state.

[0103] In an apparatus for measuring a droplet discharge amount, an inkjet printing system, and a method for measuring a droplet discharge amount according to an exemplary embodiment, droplets discharged from an inkjet head are effectively contained in a droplet containing component, thereby accurately measuring the droplet discharge amount, while suppressing the generation of a vortex of gas generated between the inkjet head and the droplet containing component and the dispersion of droplets.

[0104] The liquid droplets discharged when the liquid droplet receiving member is moved can be collected to be received, and therefore, the condition in which the liquid droplets discharged from the inkjet head fall on the moving substrate can be effectively simulated during the actual printing process to more accurately measure the actual liquid droplet discharge amount under conditions similar to the actual printing process. In addition, since the liquid droplet receiving member moves when collecting and receiving the liquid droplets, it is possible to prevent the vortex of the gas from being generated between the inkjet head and the liquid droplet receiving member, thereby effectively suppressing the contamination of the bottom surface of the inkjet head due to the dispersed liquid droplets. The contamination of the bottom surface of the inkjet head can be minimized to reduce the maintenance cost and time for cleaning the contaminated inkjet head.

[0105] The opening of the shell configured to accommodate the droplet holding component can be opened and closed by a shutter, and the shutter is provided with a stepped portion, and through such a structure, the distance between the inkjet head and the droplet holding component can be minimized. The discharged ink is accommodated in a groove provided at the edge of the droplet holding component after falling on a protrusion provided in the central portion of the droplet holding component, thereby effectively improving the droplet falling rate.

[0106] Furthermore, in the inkjet printing system according to the embodiment, the discharge amount or discharge rate of droplets discharged from the inkjet head to the substrate can be accurately controlled based on the accurately measured ink discharge amount, thereby effectively improving the inkjet printing quality.

[0107] The term "on..." used in the above description includes direct contact and indirect contact in the relative position of the upper and lower parts. Not only the entire top surface or the entire bottom surface can be positioned, but also part of the top surface or the bottom surface can be positioned, and it is used to express the meaning of being relative to or in direct contact with the upper surface or the bottom surface in position. In addition, the terms "top", "bottom", "front end", "rear end", "up", "down", "upper end", "lower end", etc. used in the above description are for the convenience of definition based on the drawings. The shape and position of each component are not limited by these terms.

[0108] In an apparatus for measuring a droplet discharge amount, an inkjet printing system, and a method for measuring a droplet discharge amount according to an exemplary embodiment, droplets discharged from an inkjet head are effectively contained in a droplet containing component, thereby accurately measuring the droplet discharge amount, while suppressing the generation of a vortex of gas generated between the inkjet head and the droplet containing component and the dispersion of droplets.

[0109] The liquid droplets discharged when the liquid droplet receiving member is moved can be collected to be received, and therefore, the condition in which the liquid droplets discharged from the inkjet head fall on the moving substrate can be effectively simulated during the actual printing process to more accurately measure the actual liquid droplet discharge amount under conditions similar to the actual printing process. In addition, since the liquid droplet receiving member moves when collecting and receiving the liquid droplets, it is possible to prevent the vortex of the gas from being generated between the inkjet head and the liquid droplet receiving member, thereby effectively suppressing the contamination of the bottom surface of the inkjet head due to the dispersed liquid droplets. The contamination of the bottom surface of the inkjet head can be minimized to reduce the maintenance cost and time for cleaning the contaminated inkjet head.

[0110] The opening of the shell configured to accommodate the droplet holding component can be opened and closed by a shutter, and the shutter is provided with a stepped portion, and through such a structure, the distance between the inkjet head and the droplet holding component can be minimized. The discharged ink is accommodated in a groove provided at the edge of the droplet holding component after falling on a protrusion provided in the central portion of the droplet holding component, thereby effectively improving the droplet falling rate.

[0111] Furthermore, in the inkjet printing system according to the embodiment, the discharge amount or discharge rate of droplets discharged from the inkjet head to the substrate can be accurately controlled based on the accurately measured ink discharge amount, thereby effectively improving the inkjet printing quality.

[0112] Although the embodiments have been described with reference to a plurality of exemplary embodiments, the embodiments are not limited to the above embodiments, and therefore, it should be understood that those skilled in the art can design numerous other modifications and embodiments, which will fall within the spirit and scope of the principles of the present disclosure. Therefore, the actual protection scope of the present invention should be determined by the technical scope of the appended claims.

Claims

1. A device for measuring the amount of liquid droplet discharge, characterized in that The device comprises: a housing provided with an opening through which droplets discharged from the inkjet head pass and configured to define an internal space; a liquid drop receiving member provided in the inner space for collecting and receiving the liquid droplets passing through the opening; a weight measuring member configured to measure the weight of the liquid droplet contained in the liquid droplet containing member; and The moving member is configured to move the droplet receiving member in a first direction.

2. The device according to claim 1, characterized in that The droplet receiving member is configured to collect and receive the droplets while moving along the first direction.

3. The device according to claim 2, characterized in that The liquid drop receiving part is configured to collect and receive the liquid drop while moving in a portion shorter than a length of the opening in the first direction.

4. The device according to claim 1, characterized in that The housing comprises: Base; a wall connected to the base to surround the interior space; and a cover connected to the upper end of the wall and having the opening, The device further comprises a shutter which slides parallel to the cover to open or close the opening.

5. The device according to claim 4, characterized in that The height of the top surface of the shutter is partially lower than or equal to the height of the top surface of the cover, and partially higher than or equal to the height of the bottom surface of the cover.

6. The device according to claim 4, characterized in that The shutter includes a stepped portion extending in a direction intersecting a sliding direction.

7. The device according to claim 1, characterized in that The droplet receiving component comprises: a wall configured to provide a receiving space for receiving the droplet; a protrusion provided at a central portion of the receiving member; and a groove provided between the wall and the projection to extend along the wall, Wherein, the inkjet head is provided on the protrusion to discharge the liquid droplets.

8. The device according to claim 1, characterized in that The weight measuring member is provided in the internal space to move in the first direction together with the droplet receiving member, and The device further includes an elastic holding member configured to hold the weight measuring member so that vibration generated during the movement is offset.

9. The device according to claim 1, characterized in that The inkjet head is configured to discharge the liquid droplets in a fixed state.

10. An inkjet printing system comprising: a substrate holder provided on the first region to hold a substrate; an inkjet head configured to discharge droplets onto the substrate to provide a coating; The device for measuring the amount of liquid droplet discharge according to any one of claims 1 to 9, provided on a second area separated from the first area; as well as An inkjet head transport member is configured to move the inkjet head between the first area and the second area in a second direction intersecting the first direction.

11. The inkjet printing system according to claim 10, characterized in that: The substrate holder includes a substrate transport member configured to move the substrate in the first direction when the inkjet head discharges the droplets toward the substrate.

12. The inkjet printing system according to claim 10, characterized in that: A controller is further included, configured to control a discharge amount or a discharge rate of the liquid droplets discharged from the inkjet head toward the substrate using the liquid droplet discharge amount measured in the device for measuring the liquid droplet discharge amount.

13. A method for measuring droplet discharge volume, the method comprising: providing an inkjet head at a droplet discharge amount measurement position; collecting liquid droplets at the liquid droplet discharge amount measurement position to supply the liquid droplets to a liquid droplet receiving member for receiving the liquid droplets; moving the droplet receiving member in a first direction; as well as The liquid droplets are discharged toward the moving liquid drop receiving member by the inkjet head.

14. The method according to claim 13, characterized in that The liquid drop receiving part is provided in an inner space of a housing in which an opening through which the liquid drop discharged from the inkjet head passes is formed, and When the droplet receiving part moves, the droplet receiving part moves in a portion shorter than the length of the opening in the first direction.

15. The method according to claim 13, characterized in that When the liquid droplets are discharged, the inkjet head discharges the liquid droplets onto a protrusion provided at a central portion of the liquid droplet receiving member.

16. The method according to claim 13, characterized in that When the liquid droplets are discharged, the inkjet head discharges the liquid droplets in a state of being fixed at the liquid droplet discharge amount measurement position.

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