KR20230039525A - Applying apparatus and droplet ejection inspection method - Google Patents

Abstract

The present invention relates to an applying apparatus and a droplet ejection inspection method, which can prevent a droplet ejected on a medium for inspection from being dried and appropriately perform droplet inspection. The applying apparatus of an embodiment of the present invention, which forms an application film on a substrate with an application liquid ejected from an inkjet-type applying head, comprises: an application head which ejects an application liquid on the medium for inspection; a droplet filming unit which films the droplet of the application liquid on the medium for inspection ejected from the application head; and a control device which obtains an area of the droplet based on an image filmed by the droplet filming unit and performs control of an ejection voltage applied to a nozzle based on the area. The droplet filming unit has a cover, which covers a droplet ejection region formed by the application liquid ejected on the medium for inspection from each nozzle of the application head, and a camera, which is provided on the top of the cover and can film a part of the cover and a part of the droplet ejection region. The cover and the camera can be integrally elevated and also be moved relative to the medium for inspection.

Description

Applicator, droplet discharge inspection method {APPLYING APPARATUS AND DROPLET EJECTION INSPECTION METHOD}

An embodiment of the present invention relates to an application device and a droplet discharge inspection method.

Conventionally, as an apparatus for applying a functional thin film to a substrate using a functional liquid, an inkjet-type liquid droplet ejection apparatus that ejects the functional liquid as liquid droplets onto a substrate is known. Droplet ejection devices are widely used, for example, when manufacturing electro-optical devices such as organic EL devices, color filters, liquid crystal display devices, plasma displays, and electron emission devices.

In the droplet ejection apparatus, the amount of droplets ejected varies from nozzle to nozzle of an inkjet coating head that ejects droplets, or there are cases where there are nozzles that do not eject droplets at all. Therefore, before droplets of the functional fluid are discharged from the coating head to the substrate, the quality of the discharge of the droplets is checked. Specifically, droplets are discharged from the coating head onto a medium for inspection, captured, image-processed to measure the area of the droplet, and discharge quality of the discharge nozzle of the coating head is inspected. Based on the inspection data of the ejection nozzle obtained in this way, the discharge amount of the nozzle of the coating head is controlled to suppress the unevenness of the droplet amount, and then the functional liquid is discharged to the substrate as the final product.

Patent Document 1: Japanese Unexamined Patent Publication No. 2010-131562

However, in the nozzle ejection inspection, since the number of cameras is limited, after the droplets for inspection are ejected from the coating head, the camera cannot image all the droplets, and the area to be imaged is divided into a plurality of areas. , the camera is scanned for these plural areas to sequentially capture images. In the case of sequentially imaging the droplets in this way, drying of the droplets proceeds in the other area while imaging one area. As drying proceeds, the area of the droplet decreases. In other words, the difference between the area of the droplet immediately after landing and the area of the droplet at the point of time when the image is captured increases in the area to be imaged later.

Embodiments of the present invention have been made in view of the above circumstances, and an object thereof is to suppress drying of droplets discharged to a test medium and appropriately perform droplet inspection.

An application device according to an embodiment is an application device for forming a coating film on a substrate with a coating liquid discharged from an inkjet-type coating head having a plurality of nozzles, comprising: the coating head for discharging the coating liquid to a medium for inspection; a droplet imaging unit for capturing an image of a droplet of the coating liquid on the test medium discharged from the coating head, and a discharge area for obtaining a droplet area based on an image captured by the droplet imaging unit and applying the droplet to the nozzle based thereon; A control device for controlling voltage, wherein the droplet imaging unit includes: a cover covering a droplet discharge area formed by the coating liquid discharged onto the test medium from each nozzle of the coating head; and a camera capable of capturing images of a part of the cover and a part of the droplet ejection area, wherein the cover and the camera are integrally capable of being lifted and moved relative to the test medium. do.

A liquid droplet discharge inspection method according to an embodiment is a method for inspecting the discharge quality of droplets discharged from an inkjet coating head having a plurality of nozzles, comprising the steps of discharging a coating liquid from the plurality of nozzles to an inspection medium; , a step of imaging a droplet of the coating liquid on the inspection medium, a step of obtaining an area of the droplet based on the captured image of the droplet, and controlling a discharge voltage applied to the nozzle based on this, , Image pickup of the droplet is characterized in that the droplet discharge area formed by the droplet on the test medium is covered with a cover, and the image is taken while relatively moving a camera integrated with the cover and the test medium.

According to the embodiment of the present invention, drying of droplets discharged to the inspection medium can be suppressed, and droplet inspection can be appropriately performed.

1 is a side schematic view of an applicator according to a first embodiment.
Fig. 2 is a plan schematic view of the applicator according to the first embodiment.
3 is a front schematic view of the applicator according to the first embodiment.
Fig. 4 is an enlarged plan view of the applicator according to the first embodiment at the time of inspecting droplet ejection quality.
Fig. 5 is a time-lapse explanatory view of the application device according to the first embodiment at the time of droplet ejection quality inspection.
6 is a side schematic view of an applicator according to a second embodiment.

<First Embodiment>

A first embodiment of the present invention will be described with reference to FIGS. 1 to 5 .

(full configuration)

As shown in FIGS. 1 to 3, the coating device 1 has a mount 2, and a substrate stage 3 for placing a substrate W on the mount 2, and the substrate stage 3 are straddled. It is constituted by providing a gate-shaped frame 4 provided on the frame 4, an inkjet coating head 5 for discharging a coating liquid (polyimide solution), and a droplet imaging unit 6 provided on the frame 4.

The substrate stage 3 is placed on a Y-axis moving device (not shown) installed on the mount 2 along the Y-axis direction, and is movable along the Y-axis direction by the Y-axis moving device. Here, as the Y-axis moving device, a feed screw-type moving mechanism using a servo motor as a driving source or a linear motor-type moving mechanism using a linear motor as a driving source can be used.

The application head 5 is attached to the frame 4 via an X-axis moving device (not shown), and is movable in the X-axis direction. Similar to the drive source for the Y-axis moving device of the substrate stage 3, this moving device can also use a feed screw-type moving mechanism or a linear motor-type moving mechanism.

(application head)

The coating head 5 is a known inkjet coating head, and a plurality of nozzles are formed on the lower surface of the coating head in two rows along the longitudinal direction. In the coating head 5, corresponding to each nozzle, a liquid chamber communicating with the nozzle is provided, and each liquid chamber is connected to a liquid supply passage through which the coating liquid is supplied. Each liquid chamber is provided with a piezoelectric element (not shown) for generating a volume change within the liquid chamber, and the volume within the liquid chamber is changed by applying a driving voltage to the piezoelectric element, whereby the coating liquid is discharged from a nozzle communicating with each liquid chamber. do.

(droplet imaging unit)

The droplet imaging unit 6 is attached to the frame 4 via the X-axis direction moving device 7 and the Z-axis moving device 8, and is on the front side of the paper than the coating head 5 in FIG. 3 It is provided in a position where it does not interfere with the application head 5. The droplet imaging unit 6 has a camera 61 and a cover 62 as shown in FIGS. 1 and 2 . The camera 61 is fixed to the cover 62, and the cover 62 is provided to the frame 4 through the X-axis moving device 7 and the Z-axis moving device 8. That is, by the movement of the cover 62, the camera 61 also moves integrally. The camera 61 is a known camera, and is provided so as to include a part of the substrate W disposed on the stage 3 in the field of view. The cover 62 is a rectangular plate-shaped member formed below the camera 61 so as to extend in the horizontal direction, and is made of, for example, transparent glass to which a low-reflection process (AR coat or the like) has been applied. The camera 61 and the cover 62 integrated with the camera 61 are attached to the frame 4 via the X-axis moving device 7 and the Z-axis moving device 8, so that the camera 61 and the cover 62 is movable in the X-axis direction and the Z-axis direction. In addition, the camera 61 may be equipped with illumination as needed. The cover 62 is for covering an area where droplets are ejected from the coating head 5 on the inspection medium K described later (droplet ejection area E), and in the X-axis direction, the droplet ejection area ( E) in the X-axis direction and twice or more in the Y-axis direction, and in the Y-axis direction, in the Y-axis direction, the liquid droplet discharge region E has a length of twice or more in the Y-axis direction, and the camera 61 is used for inspection. It has such a size that the entire droplet discharge region E is always covered with the cover 62 during imaging of the medium K.

(controller)

The application device 1 has a control device 100, is electrically connected to the application head 5, each moving device, a driving device, and a camera 61, and discharges the coating liquid of the application head 5, each Driving of the moving device and driving device and imaging of the camera 61 are controlled. In addition, the control device 100 has an image processing unit, a storage unit, and the like, accepts image data obtained by the camera 61, performs image processing, and determines the quality of discharge of the coating liquid by the coating head 5 based on this. It is possible to inspect (details will be described later). In addition, in the storage unit, application information of the coating liquid to the substrate W (information such as the application pattern and the formation position of the application pattern on the substrate) and discharge conditions of the piezoelectric element used when drawing the application pattern (piezoelectric information such as the voltage value applied to the element and the voltage application time) are stored.

In such an application device 1, when the substrate W is placed on the substrate stage 3, based on the application information stored in the control device 100 and discharge conditions, the application head 5 and each moving device , the driving device is controlled so that the coating liquid is applied on the substrate W in a predetermined pattern.

In addition, in the coating device 1, in order to discharge droplets (coating liquid) from the coating head 5 in a good manner, periodically (for example, when the application of the coating liquid to the substrate W of a set number is completed) Each time, or each time a set time has elapsed), the quality of discharge of droplets from the coating head 5 is inspected.

(droplet discharge quality test)

Hereinafter, the quality test of this liquid droplet discharge will be described.

While the application of the coating liquid to the substrate W placed on the substrate stage 3 is being executed, the control device 100 counts the number of substrates W on which application has been completed. When the preset number of sheets is reached, the droplet ejection quality check is performed before applying the coating liquid to the substrate W next supplied on the substrate stage 3 . In addition, instead of counting the number of substrates, the elapsed time may be counted.

First, the operator confirms that the substrate W does not exist on the substrate stage 3, and places the inspection medium K. The inspection medium K is, for example, a glass substrate having liquid repellency, and has a predetermined contact angle (for example, 60 to 85 degrees) with respect to an impacted droplet. In addition, the inspection medium K has a size in which liquid droplets discharged from all the nozzles of the coating head 5 can land. The control device 100 adjusts the positions of the inspection medium K and the application head 5 so that the relative positions of the inspection medium K and the application head 5 are predetermined positions suitable for the droplet discharge quality inspection. Adjust. Specifically, the inspection medium K is adjusted to be located below the nozzle (not shown) of the coating head 5, and the surface on which the nozzle of the coating head 5 is formed from the surface of the inspection medium K The height up to is adjusted so that it becomes the same height (for example, about 5 mm) as the height when the coating liquid is applied to the substrate W.

When the relative position of the test medium K and the coating head 5 is located at a predetermined position, droplets are ejected from the nozzle of the coating head 5 to the test medium K for a preset number of times (FIG. 4). . For example, a driving voltage is applied to the piezoelectric element of each nozzle once, and droplets are ejected from each nozzle once. Hundreds of nozzles are provided in each coating head 5, and hundreds of droplets are ejected to the test medium K (Fig. 4 shows a drawing in which 10 droplets are ejected for convenience). When the ejection of the preset number of times is completed, the inspection medium K is moved in the Y direction by the Y-axis moving device, and a part of the area where all the droplets are ejected (the droplet ejection area E) is moved to the droplet imaging unit 6 ) is positioned so as to come under the camera 61 (Fig. 5(A)). Here, "all droplets" refers to all droplets discharged on the inspection medium K in order to test the discharge amount, and other dummy discharges and the like are not included. The droplet imaging unit 6 is lowered by the Z-axis moving device 8 . That is, the positions of the inspection medium K and the droplet imaging unit 6 are adjusted so that the relative positions of the inspection medium K and the droplet imaging unit 6 are predetermined positions suitable for drop quality inspection. For example, the cover 62 is lowered so that the distance from the surface of the test medium K to the lower surface of the cover 62 is 5 mm or less.

When the relative position of the inspection medium K and the droplet imaging unit 6 is located at a predetermined position, the camera 61 moves the droplet of the droplet discharge area E by the X-axis moving device 7 in advance. Take pictures sequentially in order. The cover 62 of the droplet imaging unit 6 has, in the X-axis direction, twice or more the length of the droplet ejection area E in the X-axis direction, and in the Y-axis direction, the droplet ejection area E ) has a length of more than twice the length of the Y-axis direction. Since the cover 62 is integrally held with the camera 61 as described above, the cover 62 follows the movement of the camera 61 and moves. Since the size of the cover 62 is at least twice the length of the droplet ejection area in both the X-axis direction and the Y-axis direction as described above, while the camera 61 is taking an image of the inspection medium K, The entire liquid droplet discharge region E is always covered with the cover 62 .

Here, with reference to Fig. 5, a process in which the droplet imaging unit 6 sequentially captures images of the droplet discharge region E will be described.

First, the droplet imaging unit 6 starts imaging by the camera 61 from the side of the droplet E1 in the droplet ejection area E. Here, the imaging visual field of the camera 61 is demonstrated as being the same as the shape of the camera 61 shown in FIG. As shown in FIG. 5(A), the X-axis moving device 7 covers the cover 62 so that the droplet E1 located at the upper right end of the droplet discharge region E is included within the field of view of the camera 61. ) and the camera 61 is moved. Since the field of view of the camera 61 is large enough to contain 3 droplets, in this example, the camera 61 captures an image of 3 droplets from above including the droplet E1, and controls the image. Output to device 100.

Next, as shown in FIG. 5(B) , the droplet imaging unit 6 is moved in the X-axis direction by the X-axis moving mechanism 7 so that the next three droplets enter the field of view of the camera 61. do. As a result, droplets partially different from the droplets imaged before the movement enter the field of view of the camera 61 . After the camera 61 moves to a position including the droplet E2 located at the lower end of the droplet discharge region E in its field of view, it captures an image of the droplet, and the captured image is transferred to the control device 100. output to In addition, some liquid droplets are imaged overlapping, but the position of the camera 61 may be set so as not to overlap. In addition, in the part imaged overlapping, it is excluded from the target of the area calculated in the control apparatus 100 (calculation of an area will be described later).

Next, the substrate stage 3 is moved in the transport direction A1 to move the inspection medium K. As a result, as shown in FIG. 5(C) , the positional relationship in which the droplet E3 located at the lower left end of the droplet discharge region E is included in the field of view of the camera 61 is established. At this time, the droplet imaging unit 6 is in the same position as in FIG. 5(B). The camera 61 captures a droplet image after the inspection medium K is moved, and outputs the imaged image to the control device 100 .

Next, the droplet imaging unit 6 is moved in the X-axis direction by the X-axis movement mechanism 7 as shown in FIG. 5(D). This results in a positional relationship in which the field of view of the camera 61 includes the droplet E4 located at the upper left end of the droplet discharge region E. At this time, the substrate stage 3 does not move, and is in the same position as Fig. 5(C). After the camera 61 moves to a position where the droplet E4 is included in the field of view, the droplet is imaged and the imaged image is output to the control device 100 .

In this way, while changing the relative positions of the droplet imaging unit 6 and the inspection medium K, the droplet imaging unit 6 sequentially moves from the droplet E1 to the droplet E4 in the droplet ejection area E. All droplets are imaged, and these captured images are output to the control device 100. At this time, when imaging the droplet discharge region E at, for example, the position shown in FIG. ) is out of the field of view of the camera 61 but covered by the cover 62. For this reason, since the solvent vapor evaporated from the droplet discharged onto the inspection medium K stays around the droplet without diffusing, it is possible to prevent the area of the droplet from changing due to drying of the droplet E3. . Therefore, it is possible to image while preventing all the droplets present in the droplet discharge region E from drying out.

The captured image captured by the control device 100 is processed by the image processing unit. In the control device 100, the discharge amount in each nozzle of the coating head 5 is inspected based on the captured image. Specifically, the captured image is subjected to image processing by the image processing unit, the outline of the droplet is grasped, the area of the droplet is measured, and the droplet amount is converted from the measured area of the droplet to obtain the discharge amount of the nozzle. 5(A), 5(B), 5(C) and 5(D), since there are overlapping imaged droplets, the control device 100 When calculating an area, an overlapping portion included in an image captured later is excluded from the calculation target.

Then, based on the inspection result, the discharge amount of the nozzle in the coating head 5 is adjusted. For example, the required discharge amount stored in advance in the storage unit is compared with the actual discharge amount of each nozzle, and based on the comparison, the driving voltage to be applied to each nozzle is feedback-controlled.

In this way, preparations are made to place the substrate W to be coated next on the substrate stage 3 while the droplet ejection quality check is being performed. After the droplet ejection quality test is performed and the feedback control of the drive voltage applied to each nozzle is completed, an operator (may be a robot or the like) removes the inspection medium K from the substrate stage 3 and replaces the substrate W ) is placed. When the relative position of the substrate stage 3 on which the substrate W is placed and the coating head 5 is adjusted to a predetermined position by the X-axis moving device, the Y-axis moving device, and the Z-axis moving device, the coating head 5 ), the application of the functional film to the substrate W is resumed.

In this way, according to the first embodiment, after droplets are discharged onto the test medium K by the application head, a cover 62 covering the droplet discharge region E is disposed. By doing so, the cover 62 can prevent the discharged droplet from contacting air and drying. The cover 62 moves integrally with the camera 61, but since the size of the cover 62 is such that it can always cover the droplet discharge area E even when it moves, it is always possible to prevent the droplet from drying out. it becomes possible Since the camera 61 captures an image of the droplet on the test medium K through the cover 62, it is possible to suppress a change in the area of the droplet in the captured image. Therefore, between the droplet E1 imaged first and the droplet E4 imaged last, there is no difference in area due to drying, and since the amount of droplets can be accurately converted, the droplet ejection quality can be suitably inspected. In addition, since the camera 61 and the cover 62 are integrated, the work of attaching the cover 62 and repeating the positioning only when inspecting the quality of droplet discharge becomes unnecessary, and the inspection can be carried out efficiently. there is. In addition, since the cover 62 is made of low-reflection glass, it is difficult for the reflected light to reach the camera 61, and since the image of the droplet can be appropriately captured, the droplet ejection quality can be suitably inspected. Moreover, since the camera 61 always moves integrally with the cover 62, it always captures the same position of the cover 62. Since the entire cover 62 does not become equally dirty, the camera 61 scans independently of the cover 62, and each image is apically dirty compared to when another part of the cover 62 is imaged. can be detected, and appropriate abnormality detection can be performed.

<Second Embodiment>

Next, a second embodiment of the present invention will be described with reference to FIG. 6 . The application device 1 of the second embodiment further includes a maintenance unit 9 of the application head 5 .

(maintenance unit)

The maintenance unit 9 performs maintenance of the coating head 5 and solves the discharge defect of the coating head 5. The maintenance unit 9 is disposed at the end of the substrate stage 3 in the Y-axis direction, and is integrated with the substrate stage 3 to be movable in the Y-axis direction.

The maintenance unit 9 is a unit that wipes nozzles of the coating head 5 according to maintenance of the coating head 5 . The maintenance unit 9 has a wiper 91 . The wiper 91 is made of a fabric-like material having absorbent properties and is longer than the length of the nozzle formation region of the application head 5 in the longitudinal direction, and is provided so that all nozzles can be wiped. The wiper 91 is rotatably provided via the shaft S, and can limit rotational motion with a stopper not shown. When performing the wipe operation by the wiper 91, it is fixed so as not to rotate by the stopper, and when changing the surface used for wiping, the stopper can be released and rotated.

When the wiper 91 moves in the Y-axis direction together with the substrate stage 3 and moves to a position where the coating head 5 is located above it, the wiper 91 contacts the nozzle of the coating head 5 do. At this time, the wiper 91 moves in the Y-axis direction while contacting the nozzle of the coating head 5, thereby wiping the nozzle surface. The position of the cover 62 in the Z-axis direction is adjusted by the Z-axis moving mechanism 8 so that it becomes the same height as the surface on which the nozzle is formed. Thereby, after the wiper 91 of the maintenance unit 9 wipes the nozzle formation surface of the coating head 5, it can wipe the lower surface of the cover 62. The coating liquid adheres to the nozzle of the coating head 5, and a large amount of the coating liquid adheres to the wiper 91 after wiping. Therefore, it is preferable that the wiper 91, after wiping the nozzle forming surface, release the stopper and rotate itself by a driving unit (not shown) so that the other surface comes into contact with the lower surface of the cover 62. The wiper 91 wipes the lower surface of the cover 62 by moving in the Y-axis direction while contacting the lower surface of the cover 62 .

Here, the cover 62 receives the coating liquid evaporated from the droplet discharge region E while covering the droplet discharge region E. As the droplet ejection quality test is repeatedly performed, the lower surface side of the cover 62 is gradually stained or swollen due to the adhesion of the evaporated coating liquid. Then, maintenance by the wiper 91 is implemented together at the timing which performs maintenance of the coating head 5. The maintenance timing of the coating head 5 is set by obtaining in advance an experiment or the like within a range in which ejection defects or the like due to drying of the nozzle do not occur.

Alternatively, the maintenance by the wiper 91 may be performed as maintenance of only the cover 62, not simultaneously with the maintenance of the coating head 5. In this case, the cover 62 is imaged by the camera 61 and the dirty state of the cover 62 is detected, so that the cover 62 is maintained. For example, the camera 61 periodically captures an image of the cover 62 and outputs it to the control device 100 . The control device 100 image-processes and binarizes this image to detect dirt. When dirt is detected, the cover 62 may be lowered and the wiper 91 moved in the Y-axis direction to perform maintenance of the cover 62 . At this time, the coating head 5 may be retracted by a retracting unit (not shown). In addition, the image taken of the cover 62 may be used when checking the quality of droplet ejection. In this case, the droplet discharged to the inspection medium K is also included in the image, but the dirty state of the cover 62 may be detected using only a portion where no droplet exists.

Alternatively, a mark for detecting dirt may be provided at a position of the inspection medium K except for the droplet discharge region E, and the dirt of the cover 62 may be determined by capturing an image of the mark. For example, a circular pattern drawn in a lighter color toward the outside is prepared. By taking images of this mark with the camera 61 at regular intervals, a dirty state is detected. When the cover 62 is raised, the area of the mark in the captured image captured by the camera 61 is reduced. When it is less than the predetermined area, it is determined that maintenance is necessary, and maintenance such as wiping of the cover 62 is performed.

In this way, according to the second embodiment, in addition to having the same effect as the first embodiment, since the cover 62 can be kept clean, the image captured by the camera 61 becomes clear, and the droplet discharge is performed more accurately. You can check both sides.

<Modification of the second embodiment>

In the second embodiment, it was exemplified that maintenance of the cover 62 is performed by image processing of an image captured by the camera 61 to detect dirt, but it is not limited to this, and when inspecting the quality of droplet discharge, droplet imaging You may make it detect the bulging of the cover 62 from the change of the contrast of the some image imaged by the part 6. Specifically, using an image captured by the camera 61 of the droplet imaging unit 6 output to the control device 100, the contrast value of the outer edge of the droplet included in the captured image and the boundary portion outside the droplet range to measure When this contrast value is lower than a preset threshold value, it is determined that swelling has occurred in the cover 62, and maintenance of the cover 62 is performed. The maintenance of the cover 62 performs wiping by the wiper 91 of the maintenance unit 9 mentioned above.

In this way, according to this modified example, in addition to having the same effect as the first embodiment and the second embodiment, the buoyancy of the cover 62 can be determined using the captured image used for the droplet discharge quality inspection. The number of times of image pickup by the camera 61 and image processing of the captured image can be reduced to a minimum, making it possible to efficiently inspect droplet discharge.

<Other embodiments>

Further, in the above embodiment, the cover 62 has been exemplified as having a plate shape, but is not limited to this, and may be of a box shape covering the camera 61, for example. In this case, the lower surface of the box is made of transparent glass subjected to low-reflection processing, and the other surfaces (wall surface portions) can be made of black plate-like materials. By making the wall surface portion black, it is possible to prevent reflected light from entering the camera 61, and it is possible to more accurately check the quality of droplet ejection.

In the above embodiment, the droplet imaging unit 6 is exemplified as being movable in the X-axis direction and the Z-axis direction, but is not limited to this, and may be movable in the Y-axis direction and rotational direction, for example. .

Further, in the above embodiment, it is exemplified that the test medium K is placed on the substrate stage 3 to check the droplet ejection quality. A disposition portion may be provided, and after maintenance of the coating head 5 and the cover 62, the test medium K may be moved in the Y direction to perform droplet ejection quality check.

In the above embodiment, the test medium K is liquid-repellent glass as an example, but is not limited thereto, and may be of a film type or a shape other than a rectangular shape (e.g., circular shape or polygonal shape). Alternatively, an end portion of the substrate W for forming a coating film or the like may be used as a medium for inspection, which becomes unnecessary when making the final product.

In the above embodiment, maintenance of the cover 62 is exemplified when the contrast value is less than the threshold value, but the correction value is not limited to this, and based on the obtained contrast value, a correction value obtained in advance through an experiment. The area of the droplet may be converted using

Further, in the above embodiment, it is exemplified that the cover 62 is automatically wiped with the wiper 91 when dirt or swelling of the cover 62 is detected, but it is not limited to this, and the dirt of the cover 62 A warning message may be displayed on a display unit within the device, a lamp may be turned on, or a warning sound may be sounded so as to notify the operator that the floatation load has been detected. Based on this, the cover 62 may be replaced with another new cover, or the cover 62 may be cleaned manually.

Further, in the above embodiment, it has been exemplified that the maintenance unit 9 is provided with a wiper 91, which is a cloth-type roll wiper, but is not limited thereto, and known A maintenance member of the inkjet type coating head may be used in combination or replaced.

In the above embodiment, the case of one coating head 5 has been exemplified, but it is not limited to this, and a plurality of coating heads 5 may be provided. In the case where a plurality of coating heads 5 are provided, droplet inspection may be performed for each head or may be performed at a plurality of times. Either way, it is sufficient to provide a cover 62 having a length capable of covering the droplet discharge region E, which is an object of inspection at one time.

Further, in the above embodiment, the length of the wiper 91 has been exemplified as being longer than the length in the longitudinal direction of the nozzle formation region of the coating head 5, but is not limited to this, and within the range provided for nozzle discharge Of the lengths and the lengths of the droplet ejection regions E on the inspection medium K, it may be equal to or longer than the longest length.

In the above embodiment, the area of the droplet is measured based on the image captured by the camera 61, and the discharge amount of each nozzle is obtained from this area, but it is not limited to this, and the area and nozzle A correspondence table of correction values of voltages to be applied may be stored in a storage unit, and corresponding voltages may be applied.

As mentioned above, several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the range of equivalents thereof.

1 applicator
5 applicator head
K test medium
W board
E Droplet discharge area
6 droplet imaging unit
61 camera
62 cover
100 control unit
9 maintenance unit
91 wiper

Claims (11)

A coating device for forming a coating film on a substrate with a coating liquid discharged from an inkjet coating head having a plurality of nozzles, comprising:
the coating head for discharging the coating liquid to a test medium;
a droplet imaging unit configured to image droplets of the coating liquid on the test medium discharged from the coating head;
A control device for obtaining an area of a droplet based on an image captured by the droplet imaging unit and controlling a discharge voltage applied to the nozzle based on the area of the droplet.
have
The droplet imaging unit,
a cover covering a droplet discharge area formed by the coating liquid discharged onto the test medium from each nozzle of the coating head;
A camera provided above the cover and capable of imaging the droplet on the test medium through the cover
have
The coating device according to claim 1, wherein the cover and the camera are integrally capable of being lifted and moved relative to the medium for inspection. The application device according to claim 1, wherein the cover has a rectangular shape, and both sides of the cover each have a length twice or more than both sides of the droplet discharge region. The applicator according to claim 1 or 2, wherein the control unit judges the presence or absence of dirt or swelling of the cover based on an image captured by the camera. 4. The method according to claim 3, wherein the droplet imaging unit images a mark for detecting dirt provided at a position of the inspection medium excluding the droplet ejection area at predetermined intervals;
The mark for detecting dirt is a circular pattern in which the color becomes lighter as it goes outward from the center,
The application device, characterized in that the control device determines that dirt or swelling has occurred on the cover when the area of the mark for detecting dirt imaged by the droplet imaging unit is less than a predetermined area. The method according to claim 1, wherein the control unit, when a contrast value between an outer edge of the droplet included in the image captured by the camera and a boundary portion outside the droplet range is less than a predetermined threshold value, removes dirt or dust from the cover. An applicator characterized in that it is determined that there is a buoyancy load. The method according to claim 1 or 2, wherein the application device further includes a maintenance unit that cleans the application head,
The applicator characterized in that the cleaning of the cover is performed by the maintenance unit. The method of claim 3, wherein the application device further includes a maintenance unit that cleans the application head,
The applicator characterized in that the maintenance unit cleans the cover when it is determined by the control device that there is dirt or swelling on the cover. The method of claim 5, wherein the application device further includes a maintenance unit that cleans the application head,
The applicator characterized in that the maintenance unit cleans the cover when it is determined by the control device that there is dirt or swelling on the cover. The applicator according to claim 7, wherein the applicator head is cleaned and the cover is cleaned by the maintenance unit at a timing preset by the control device. The applicator according to claim 8, wherein the applicator head is cleaned and the cover is cleaned by the maintenance unit at a timing preset by the control device. A method for inspecting the ejection quality of droplets ejected from an inkjet-type coating head having a plurality of nozzles, comprising:
a step of discharging a coating liquid from the plurality of nozzles to an inspection medium;
a step of imaging the droplets of the coating liquid on the medium for inspection;
A step of obtaining an area of the droplet based on a captured image of the droplet and controlling a discharge voltage applied to the nozzle based on the area of the droplet
have
The imaging of the droplet is performed by covering the droplet discharge area formed by the droplet on the test medium with a cover, moving a camera integrated with the cover, and the test medium relative to each other through the cover on the test medium. A droplet discharge inspection method characterized by capturing an image of the droplet.

Images