Method and device for detecting liquid pool at lower end of nozzle

Abstract

[Problem] To provide a technique with which it is possible to simply and accurately determine a liquid pool generated at the lower end of a nozzle. [Solution] Provided are a method for detecting a liquid pool at the lower end of a nozzle of a liquid material ejection device, and a detection device that executes the method. The method comprises: a first step in which a nozzle 103 is moved to a detection position on a detection surface; a second step in which the nozzle 103 is lowered until the distance between the lower end of the nozzle 103 and the detection surface 107a reaches a predetermined detection distance L and, is raised once the predetermined detection distance L is reached; and a third step in which a liquid pool at the lower end of the nozzle 103 is detected by detecting whether a liquid material is attached to the detection surface 107a by the detection device 104.

Description

Method and device for detecting liquid accumulation at the bottom end of a nozzle

[0001] The present invention relates to a method and device for detecting whether liquid material has accumulated at the lower end of a nozzle in a liquid material application device.

[0002] Dispensing devices are used to apply liquid materials in the manufacturing process of electronic components, etc. For example, dispensers are used in the process of applying liquid resin to semiconductor elements mounted on a circuit board. When a dispenser is used to continuously apply liquid to a workpiece, liquid can accumulate at the tip of the nozzle, which can affect the accuracy of the application. In particular, dispensers using the flying discharge method, which have become increasingly popular in recent years, have been affected by liquid accumulation at the tip of the nozzle, causing problems such as the liquid not leaving the nozzle and not flying, the amount of liquid that does fly being either too much or too little, or not flying along the central axis of the nozzle.

[0003] Conventionally, methods for dealing with liquid accumulation at the nozzle tip have included installing a camera to observe the nozzle tip from the side and detecting abnormalities at the nozzle tip through images (Patent Document 1), and performing a test coating on a plate that is not the target for coating, observing this with a camera, and determining whether the amount of coating is acceptable (Patent Document 2).

[0004] JP 2014-236136 JP 4-334568

[0005] However, the method of capturing an image of the nozzle tip to determine whether the amount of liquid puddle is within the allowable range has the problem that it is difficult to determine whether the amount of liquid puddle exceeds the allowable range when it occurs at the bottom end of the nozzle.Furthermore, the method of capturing an image of the nozzle tip to determine whether the amount of liquid puddle is within the allowable range has the problem that it is necessary to secure a location for installing a camera that takes an image of the nozzle tip from the side and to install an optical system for observation.

[0006] On the other hand, the method of determining quality through test application has the problem that the difference between normal and abnormal application results is small, making it difficult to determine whether the amount of liquid pooling at the bottom end of the nozzle exceeds the allowable range.

[0007] An object of the present invention is to provide a technique that enables easy and highly accurate determination of liquid accumulation occurring at the lower end of a nozzle.

[0008] In a dispenser using a flying discharge method, as discharge continues, a pool of liquid may form at the nozzle tip (especially the bottom end) and gradually spread over the entire tip. Figure 8 is a schematic diagram illustrating the state in which a pool of liquid forms and progresses at the nozzle tip, where (A) shows a side view of the nozzle 801 and (B) shows a bottom view of the nozzle 801. The nozzle 801 is cylindrical, and its end is composed of a hole 802 through which the liquid material 804 is discharged and a wall 803 surrounding the hole 802. Immediately after the pool of liquid 804 forms, it spreads to approximately the same diameter as the hole 802 (Figure 8(1)). As discharge continues and the amount of pooled liquid 804 increases, it begins to spread beyond the hole 802 and onto the wall 803 (Figure 8(2)). As the ejection continues and the amount of accumulated liquid 804 increases, it spreads over the entire surface of the wall portion 803 and reaches the outer edge (FIG. 8C).

[0009] The inventors have made the following findings during their research and developed the present invention based on these findings. Figure 7 is a schematic diagram illustrating a method for detecting a liquid puddle by test application. (A) shows a side view of a nozzle 701 and a surface 702 to be coated, and (B) shows a top view of the surface 702 to be coated. In Figure 7, (1) shows the state immediately after the liquid puddle 703 has formed, (2) shows the state where the liquid puddle 703 has begun to grow, and (3) shows the state where the liquid puddle 703 has spread to most of the nozzle 701. In the test application method shown in Figure 7, a liquid puddle is determined based on the diameter of the liquid material 703 applied to the surface 702 to be coated as a result of test application, for example. In the test application method, the application result when the liquid puddle has grown (diameter D3) is significantly different from the application result when the liquid puddle has just begun to grow (diameter D2), making it easier to determine the presence of a liquid puddle. However, the difference between the application result when the liquid pooling begins to progress (diameter D2) and the application result immediately after the liquid pooling occurs, i.e., when the application is almost normal (diameter D1), is small, making it difficult to judge even if the captured image is processed. In other words, the test application method may miss the state in which the liquid pooling begins to progress (Figure 7 (2)), and may result in abnormal application being continued.

[0010] FIG. 6 shows a schematic diagram illustrating a method for detecting a puddle according to the present invention. (A) shows a side view of the nozzle 601 and the detection surface 602a, and (B) shows a top view of the detection surface 602a. (1) shows the state immediately after the occurrence of the puddle 603, (2) shows the state when the puddle 603 has begun to grow, and (3) shows the state when the puddle 603 has spread to most of the nozzle 601. In the method of the present invention shown in FIG. 6, a puddle is determined based on whether or not the liquid material 603 adheres to the detection surface 602a, as will be described in detail later. According to the method of the present invention, the liquid material 603 adheres to the detection surface 602a in both the execution result when the puddle has grown ( FIG. 6(3) ) and the execution result when the puddle has just begun to grow ( FIG. 6(2) ). However, the liquid material 603 does not adhere to the detection surface 602a in the execution result immediately after the occurrence of the puddle, i.e., in a normal state ( FIG. 6(1) ). In other words, the method of the present invention can detect with high accuracy even the state ((2)) when liquid accumulation has begun to progress, and can prevent application from continuing with an unacceptable liquid accumulation at the nozzle tip.

[0011] The method for detecting a liquid puddle at the bottom end of a nozzle of the present invention comprises the following technical means: [1] A method for detecting a liquid puddle at the bottom end of a nozzle of a liquid material discharge device, the method comprising: a first step of moving the nozzle to a detection position on a detection surface; a second step of lowering the nozzle until a predetermined detection distance is reached between the bottom end of the nozzle and the detection surface and then raising the nozzle when the predetermined detection distance is reached; and a third step of detecting a liquid puddle at the bottom end of the nozzle by detecting whether liquid material is attached to the detection surface using a detection device. [2] The method for detecting a liquid puddle at the bottom end of a nozzle described in [1], in which no liquid material is discharged from the nozzle while the second step is being performed. [3] The method for detecting a liquid puddle at the bottom end of a nozzle described in [1] or [2], in which the nozzle is a nozzle having a single discharge port at its bottom end. [4] The method for detecting a liquid puddle at the bottom end of a nozzle described in any of [1] to [3], in which the nozzle is a cylindrical or tapered nozzle. [5] The method for detecting a liquid puddle at the lower end of a nozzle according to any one of [1] to [4], wherein the detection device is an imaging device, a laser displacement meter, or an ultrasonic sensor. [6] The method for detecting a liquid puddle at the lower end of a nozzle according to any one of [1] to [5], wherein the detection surface is any one of the upper surface of a plate-shaped detection member, the upper surface of a tape-shaped member, and an unused area on the upper surface of a workpiece. [7] The method for detecting a liquid puddle at the lower end of a nozzle according to any one of [1] to [6], wherein the predetermined detection distance is set within a range of 1 / 2 to 2 times the outer diameter of the lower end of the nozzle, or 1 / 3 to 7 times the diameter of the nozzle outlet. [8] A liquid material application method including: an application step of discharging a liquid material from the nozzle onto a workpiece; and a liquid puddle detection step of performing the method for detecting a liquid puddle at the lower end of a nozzle according to any one of [1] to [7] before or after the application step. [9] The liquid material application method according to [8], further including a step of cleaning the lower end of the nozzle if the liquid material is detected to be attached to the detection surface in the liquid puddle detection step.

[10] The liquid material application method according to [9], further comprising a post-cleaning application step of ejecting liquid material from the nozzle onto the workpiece after the cleaning is performed.

[11] The liquid material application method according to [8], further comprising: a carry-in step of carrying the workpiece to a coating position, which is carried out before the coating step; and a carry-out step of carrying the workpiece out of the coating position, which is carried out after the coating step; and the liquid puddle detection step being carried out in parallel with either the carry-in step or the carry-out step.

[0012] The present invention also provides a device for detecting a liquid puddle at the bottom of a nozzle, comprising the following technical means:

[13] A device for detecting a liquid puddle at the bottom of a nozzle, comprising: a moving device that moves a discharge device having a nozzle over a detection surface; a detecting device that detects liquid material adhering to the detection surface; and a detection control device that controls the operation of the moving device and the detecting device, wherein the detection control device executes the following steps: a first step of moving the nozzle over the detection surface using the moving device; a second step of lowering the nozzle until a predetermined detection distance is reached between the bottom of the nozzle and the detection surface and then raising the nozzle when the predetermined detection distance is reached; and a third step of detecting a liquid puddle at the bottom of the nozzle by using the detecting device to detect whether liquid material is adhering to the detection surface.

[14] The device for detecting a liquid puddle at the bottom of a nozzle described in

[13] , wherein the detection control device has a function of setting the predetermined detection distance.

[15] The device for detecting a liquid puddle at the bottom of a nozzle described in

[13] or

[14] , wherein the moving device is capable of moving the detecting device over the detection surface.

[0013] The coating apparatus of the present invention is also composed of the following technical means.

[16] A coating apparatus comprising: a device for detecting liquid accumulation at the lower end of a nozzle according to any one of

[13] to

[15] ; a discharge device having a nozzle; a work table for holding a work; a stand on which the work table is disposed; a transport device for transporting the work to the work table; and a coating control device for controlling the operation of the discharge device and the movement device, wherein the coating is performed on the work while the movement device moves the discharge device and the work relative to each other based on a relative movement command from the coating control device.

[17] The coating apparatus according to

[16] further comprises: a cleaning device on the stand for cleaning the lower end of the nozzle; and when the detection control device detects that liquid material is attached to the detection surface in the third step, the detection control device executes a fourth step of cleaning the lower end of the nozzle using the cleaning device.

[18] The coating apparatus according to

[16] , further comprising an alarm device that issues a visually or audibly recognizable alert, wherein the detection control device executes a fourth step of issuing the alert by the alarm device when it is detected in the third step that the liquid material is adhered to the detection surface.

[19] The coating apparatus according to any of

[16] to

[18] , wherein the detection control device has a function of setting conditions related to the timing of executing the first to third steps.

[20] The coating apparatus according to any of

[16] to

[19] , wherein the discharge device is a flying discharge type dispenser that discharges droplets in flying form from the discharge opening of the nozzle.

[0014] According to the present invention, it is possible to easily and accurately determine whether a liquid pool has occurred at the lower end of the nozzle.

[0015] 1 is a block diagram of a liquid puddle detection device according to an embodiment; 2 is a flowchart of a liquid puddle detection method according to an embodiment; 3 is an explanatory diagram illustrating a liquid puddle detection method according to an embodiment; 4 is a perspective view of a coating device according to an embodiment; and 5 is a flowchart of a coating method according to an embodiment. 6 is a schematic diagram illustrating a method for detecting a liquid puddle using a method of the present invention, where (A) is a side view of a nozzle and (B) is a top view of a detection surface. 7 is a schematic diagram illustrating a method for detecting a liquid puddle by test coating, where (A) is a side view of a nozzle and (B) is a top view of the detection surface. 8 is a schematic diagram illustrating the state in which a liquid puddle occurs at the tip of a nozzle and progresses, where (A) is a side view of a nozzle and (B) is a bottom view of the nozzle.

[0016] The present invention detects the presence of a liquid puddle at the bottom end of the nozzle by lowering the discharge device until the bottom end of the nozzle is at a predetermined detection distance from the detection surface and detecting whether or not the liquid material is attached to the detection surface. Hereinafter, an embodiment of the present invention will be described.

[0017] 1, the liquid puddle detection device 101 of this embodiment is composed of a discharge device 102, a detection device 104, a movement device 105, and a detection control device 106. The dotted line extending from the detection control device 106 is a cable for transmitting and receiving control signals.

[0018] The ejection device 102 is a so-called flying ejection type ejection device that includes a nozzle 103 with a single circular ejection outlet at its tip for ejecting the liquid material. The ejected liquid material separates from the nozzle before reaching the coating surface. The ejection device 102 is held by a moving device 105 so that the tip of the nozzle 103 is located at the bottom. Examples of the flying ejection type of the ejection device include a method in which a rod-shaped member moves back and forth within a liquid chamber communicating with the nozzle to apply inertial force to the liquid material for ejection, a method in which the volume of a liquid chamber communicating with the nozzle is changed for ejection, and a method in which bubbles are generated on a heating element provided within a liquid chamber communicating with the nozzle for ejection. Note that while the present embodiment illustrates a configuration including a cylindrical nozzle extending straight downward, the shape of the nozzle is not particularly limited as long as it has an ejection outlet at its tip. For example, a tapered nozzle or a curved cylindrical nozzle may also be used. Furthermore, the nozzle to which the technical concept of the present invention is applicable is not limited to a nozzle having a single outlet formed at the tip of a cylindrical or approximately conical shape, but may also be, for example, an orifice nozzle having one or more outlets formed by drilling into a flat lower end surface.

[0019] The detection surface 107a of the detection member 107 is a flat surface for adhering to a puddle at the tip (lower end) of the nozzle 103 of the discharge device 102 when a puddle detection method described below is performed. The detection member 107 only needs to have a flat surface on the upper surface, and can be, for example, a plate-like member, a tape-like member made of paper or cloth stretched across in a retractable manner, or an unused area of ​​a product substrate (work).

[0020] The detection device 104 is a device for detecting whether or not a liquid material is present on the detection surface 107 a. The detection device 104 may be, for example, an imaging device (camera), a laser displacement meter, an ultrasonic sensor, or the like, as long as it can detect the presence of a liquid material adhering to the detection surface 107 a. The adhesion of the liquid material to the detection surface 107 a is detected by the detection control device 106 based on a signal from the detection device 104.

[0021] The moving device 105 is a device that moves the discharging device 102 and the detection device 104 relative to the detection surface 107a. For example, a so-called industrial robot such as an orthogonal type or a SCARA type can be used as the moving device 105. The moving device 105 of this embodiment is configured to move the discharging device 102 and the detection device 104 independently, but may also be configured to move the discharging device 102 and the detection device 104 integrally.

[0022] The detection control device 106 is an information processing device that controls the operations of the above-mentioned discharge device 102, detection device 104, and movement device 105 and executes the liquid puddle detection method described below, and includes an arithmetic unit and a storage device. For example, a personal computer (PC) or a programmable logic controller (PLC) can be used. The storage device included in the detection control device 106 stores a detection program for executing the liquid puddle detection method of the present invention.

[0023] 4, the detection member 107, the detection device 104, the moving device 105, and the detection control device 106 can be used as a calibration table 415, a measuring device 414, a driving device 403, and a coating control device 413, respectively, which will be described later, thereby preventing an increase in the size and cost of the device. In this case, the coating control device 413 has a function as a coating control device that controls the operation of the discharge device 102 and the moving device 105 to perform coating on the workpiece, and a function as a detection control device that controls the operation of the detection device 104 and the moving device 105 to detect a liquid puddle at the nozzle tip.

[0024] <Liquid Puddle Detection Method> A method for detecting a liquid puddle at the tip of the nozzle 103 using the above-described liquid puddle detection device 101 will be described. The liquid puddle detection method of this embodiment is implemented by the detection control device 106 executing a detection program. Fig. 2 is a flowchart showing the steps of the liquid puddle detection method of this embodiment, and Fig. 3 is an explanatory diagram explaining the steps of the liquid puddle detection method of this embodiment.

[0025] (STEP 201) First, the discharging device 102 is moved by the moving device 105 to a detection position (XY coordinates) on the detection surface 107a (FIG. 3(a)). Here, the Z-direction position of the discharging device 102 at the detection position is assumed to be higher than the Z coordinate corresponding to the predetermined detection distance L described below. In this specification, the step of STEP 201 may be referred to as the first step. (STEP 202) Next, the moving device 105 lowers the nozzle 103 of the discharging device 102 toward the detection surface 107a to approach the predetermined detection distance L (FIG. 3(b)). At this time, the discharging device 102 does not perform a discharging operation, but if a liquid puddle exceeding the allowable range has occurred, the liquid material will adhere to the detection surface 107a. Here, the predetermined detection distance L is determined depending on the amount of liquid puddle to be detected. In other words, the predetermined detection distance L, which is the distance between the tip of the nozzle 103 and the detection surface 107a, is determined depending on the allowable amount of liquid puddle. In this embodiment, the allowable amount of liquid accumulation is defined as the distance (predetermined detection distance L) from the lower end surface of the nozzle 103 to the tip (bottom) of the liquid accumulation. The predetermined detection distance L varies depending on the physical properties (density, viscosity, etc.) of the liquid material and the ambient environment (temperature, humidity, etc.). However, for example, in the case of a nozzle with a circular tip, it is preferably set to 1 / 2 to 2 times the outer diameter of the nozzle tip, or in the case of a nozzle with a circular discharge port (including the above-mentioned orifice nozzle), it is preferably set to 1 / 3 to 7 times the diameter of the nozzle discharge port. If it is desired to detect a smaller amount of liquid accumulation (i.e., an early stage of liquid accumulation), the predetermined detection distance L is shortened, and if it is acceptable to detect a larger amount of liquid accumulation (i.e., a more advanced stage of liquid accumulation), the predetermined detection distance L is lengthened. Furthermore, the predetermined detection distance L is preferably set shorter than the distance between the nozzle and the surface to be applied during application.

[0026] (STEP 203) Next, the ejection device 102, whose nozzle 103 is at a predetermined detection distance L, is raised by the moving device 105 and moved horizontally from the detection position. Here, the amount of lift of the ejection device 102 may be any amount of movement. In this specification, the processes of STEPs 202 and 203 may be referred to as the second process. (STEP 204) Next, the moving device 105 moves the detection device 104 to a detection position on the detection surface 107a ( FIG. 3(c) ). The detection position (XY coordinates) to which the detection device 104 moves is the same as the detection position (XY coordinates) to which the ejection device 102 moved in STEP 201. Here, the Z-direction position of the detection device 104 located at the detection position may be any Z coordinate, as long as it does not come into contact with the liquid material on the detection surface 107a. When the moving device 105 is configured to move the discharge device 102 and the detection device 104 integrally, the horizontal movement of the discharge device 102 in STEP 203 and the horizontal movement of the detection device 104 in STEP 204 can be performed simultaneously.

[0027] (STEP 205) The detection control device 106 determines whether or not the liquid material 110 is attached to the detection surface 107a based on the measurement signal from the detection device 104 (FIG. 3(d)). If the liquid material 110 is attached to the detection surface 107a, it is determined that a liquid pool exceeding the allowable range has occurred at the tip of the nozzle 103. On the other hand, if the liquid material 110 is not attached to the detection surface 107a, it is determined that a liquid pool exceeding the allowable range has not occurred at the tip of the nozzle 103. In this specification, the steps 204 and 205 may be referred to as the third step.

[0028] As described above, by simply moving the discharge device 102 toward and away from the detection surface 107a up to the predetermined detection distance L without performing a discharge operation and checking whether the liquid material 110 is attached to the detection surface 107a, it is possible to detect whether an unacceptable amount of liquid has accumulated at the tip of the nozzle 103 of the discharge device 102. Furthermore, by setting the predetermined detection distance L to a small value, it is possible to detect even a small amount of liquid accumulated at the tip of the nozzle 103.

[0029] <Coating Apparatus> A coating apparatus for implementing the above-described liquid puddle detection method will now be described. As shown in Figure 4, a coating apparatus 401 of this embodiment is mainly composed of a discharge device 402 that discharges a liquid material, and a relative drive device 403 that relatively moves the discharge device 402 and a work table 410 on which a coating target (workpiece) 411 is placed.

[0030] The relative drive device 403 is composed of an X drive device 404 that moves the discharge device 402 and the work table 410 relatively in the X direction 407, a Y drive device 405 that moves the discharge device 402 and the work table 410 relatively in the Y direction 408, and a Z drive device 406 that moves the discharge device 402 and the work table 410 relatively in the Z direction 409. In this embodiment, the Y drive device 405 is provided on the upper surface of the base 412 to extend in the Y direction 408, and the X drive device 404 is provided on the Y drive device 405 to extend in the X direction 407. The Z drive device 406 is provided on the X drive device 404, and the discharge device 402 is provided on the Z drive device 406. The work table 410 is installed on the upper surface of the base 412 so as to be parallel to the Y drive device 405 and to be located below the X drive device 404. As a result, the discharge device 402 and the object to be coated 411 on the work table 410 can be moved relatively in the X direction 407, the Y direction 408, and the Z direction 409. The relative drive device 403 is controlled by the coating control device 413 and can move the nozzle tip of the discharge device 402 to any position on the object to be coated 411 at any speed. The relative drive device 403 can be, for example, a device combining an electric motor such as a servo motor or a stepping motor with a ball screw, a device using a linear motor, or a device that transmits power via a belt or chain. This relative drive device 403 also serves as the moving device 105 of the liquid puddle detection device 101.

[0031] The discharge device 402 is equipped with a nozzle for discharging the liquid material, and its operation is controlled by a coating control device 413. The coating control device 413 can control the discharge device 402 in conjunction with the operation of the relative drive device 403. A flying discharge type discharge device (dispenser) is used as the discharge device 402. This discharge device 402 corresponds to the discharge device 102 of the liquid puddle detection device 101 shown in FIG. 1. The discharge device 402 is held by the relative drive device 403 so that the nozzle tip is at the bottom.

[0032] The coating device 401 of this embodiment includes a conveying device 418. The conveying device 418 is composed of a rail 419, a transmission element (not shown), and a conveying drive device 420. The rail 419 is composed of two members extending parallel to the Y direction 408. The rail 419 is installed so that the distance between the two members is the same as the distance between one side of the object to be coated 411. The rail 419 is provided with a transmission element that functions to convey the object to be coated 411 along the extension direction of the rail 419. The transmission element may be a belt or a chain. The transmission element is driven by a conveying drive device 420. The conveying drive device 420 may be an electric motor such as a servo motor or a stepping motor. Due to the action of the transmission element driven by the conveying drive device 420, the object to be coated 411 is conveyed along the rail 419 in a conveying direction 421. The transport device 418 is connected to a coating control device 413, and the transport speed, start and stop of transport, etc. are controlled.

[0033] The work table 410 is made of a rectangular parallelepiped member and can be raised and lowered by an elevator (not shown). The work table 410 is installed so as to be sandwiched between rails 419 of a conveying device 418. The width of the work table 410 in the X direction 407 is slightly smaller than the distance between the rails 419 of the conveying device 418 so as not to come into contact with the rails 419 of the conveying device 418. When conveying the object 411 to be coated, the work table 410 lowers to a position where it does not come into contact with the object 411 to be coated. When coating the object 411 to be coated, the work table 410 rises to sandwich and fix the object 411 to a pressure plate (not shown) provided on the rails 419. To more securely fix the object 411 to be coated, for example, a mechanism may be used in which multiple holes leading from the inside of the work table 410 to the top surface are drilled and air is sucked through the holes to adsorb the object 411 to be coated.

[0034] The coating apparatus 401 of this embodiment may be provided with a measuring device 414. The measuring device 414 is mounted on the Z-axis drive device 406 together with the dispensing device 402 and can move relative to the coating target 411 on the work table 410. The measuring device 414 may be composed of, for example, an imaging device and a length measuring device. The imaging device can capture images of components, identification marks, and the coated liquid material on the coating target 411. A CCD camera or the like can be used as the imaging device. The length measuring device can measure the distance to the surface of the coating target 411, the surface of components on the coating target 411, or the surface of the liquid material coated on the coating target 411. From these measurements, the height of the components or the coated liquid material can be determined. A laser displacement meter or the like can be used as the length measuring device. The images captured by the imaging device and the distances measured by the length measuring device are used to check the state of the coated liquid material and to position the nozzle of the dispensing device 402 relative to the coating target 411. The imaging device and the length measuring device may be integrally mounted using a mounting plate. The measuring device 414 is connected to the application control device 413 and can control the operation and store and process the measurement results. The measuring device 414 also serves as the detection device 104 of the liquid puddle detection device 101.

[0035] The coating device 401 of this embodiment includes a calibration table 415. The calibration table 415 is installed near the work table 410 on the upper surface of the base 412, within a range within which the relative drive device 403 can move the discharge device 402. The calibration table 415 has a surface (upper surface) onto which the liquid material can be applied, and this surface constitutes a detection surface. The liquid material is applied to this surface, and the shape and dimensions of the applied liquid material are confirmed using the aforementioned measuring device. Based on the results, adjustments can be made so that the liquid material to be applied to the coating target 411 has the desired shape and dimensions. Alternatively, the calibration table 415 may be configured by separately preparing a plate-like body having a surface onto which the liquid material can be applied and fixing the plate-like body using the aforementioned suction and fixing mechanism. This calibration table 415 also serves as the detection member 107 having the detection surface 107a of the liquid puddle detection device 101.

[0036] The coating control device 413 is composed of a processing device, a storage device, an input device, an output device, and a display device. In this embodiment, it is composed of an information processing device incorporating a processing device and a storage device, and a touch panel (not shown) that also serves as an input device, an output device, and a display device. However, without being limited to these, a personal computer (PC) or a programmable logic controller (PLC) can be used as the information processing device, and a keyboard, a mouse, a display, etc. can be used as the input device, the output device, and the display device.

[0037] The coating device 401 of this embodiment can be connected to a teaching terminal (not shown). The teaching terminal can teach the position of the relative drive device 403, the operation of the discharge device 402, and the like. The taught content is stored in the coating control device 413. The coating control device 413 can sequentially arrange multiple related teaching content and play it back as a single unit. In other words, the coating control device 413 is equipped with a coating program for operating the discharge device 402 and the relative drive device 403 in accordance with the teaching content. The teaching terminal can be, for example, a dedicated terminal equipped with a simple display device and multiple switches, or a personal computer with dedicated software installed. The teaching terminal can start and stop the operation of the coating device 401 based on the coating program stored in the coating control device 413. Instead of the teaching terminal, teaching can also be performed using the above-mentioned coating control device 413 and a touch panel. The coating control device 413 stores the above-mentioned detection program in a storage device, and by executing the detection program, the liquid puddle detection method of this embodiment can be performed. In the embodiment shown in FIG. 4, the coating control device 413 is configured to also function as the detection control device 106 described above, but a detection control device that is physically separate from the coating control device may also be provided.

[0038] The top of the stand 412 on which the discharge device 402, relative drive device 403, work table 410, etc. are mounted is covered with a cover 417 shown by a dotted line. Note that a portion of the cover is cut off in FIG. 4 for convenience of explanation. By providing the cover 417, it is possible to prevent dust from entering the coating device 401 and to prevent inadvertent contact between an operator and moving parts such as the relative drive device 403. Although not shown, the cover 417 may be provided with an openable / closable door to allow an operator to easily access the coating device 401. The cover 417 may also be provided with the aforementioned touch panel so that it can be operated from outside the cover 417. Furthermore, the cover 417 may be provided with an opening for loading the coating target 411 into the coating device 401 or unloading the coating target 411 from the coating device 401.

[0039] <Coating Method> A coating method using the coating device described above will be described. The coating method of this embodiment is implemented by the coating control device 413 executing a coating program. Fig. 5 shows a flowchart of the coating method of this embodiment. Note that Fig. 5 describes a coating method in which puddle detection at the nozzle tip is performed at the start of a coating operation, but it is also possible to detect puddle at the nozzle tip after coating operations (i.e., coating processes) have been performed on a predetermined number of workpieces.

[0040] When a command to start the coating operation is issued, the transport device 418 transports an uncoated substrate, which will serve as the coating target 411, into the coating apparatus (STEP 501). Next, the puddle detection method of the above-described embodiment (STEPs 201 to 205 in FIG. 2) is performed (STEP 502). If the execution of the puddle detection method determines that the liquid material is attached to the upper surface of the calibration table 415, which serves as the detection surface, the process proceeds to STEP 507, which will be described later. If the liquid material is not attached to the detection surface (calibration table), the discharge device 402 is moved relative to the substrate by the relative drive device 403, and coating is performed (STEPs 503 and 504). The substrate, upon completion of coating, is then transported out of the coating apparatus by the transport device 418 (STEP 505). If there are still uncoated substrates, which will serve as the coating target 411, the process returns to STEP 501, and uncoated substrates are transported into the coating apparatus. If there are no uncoated substrates, the process ends (STEP 506).

[0041] If adhesion of the liquid material to the detection surface is confirmed in STEP 503, this indicates that a liquid has accumulated at the nozzle tip of the dispensing device, and application is stopped to clean the nozzle (STEP 507). For example, a configuration can be adopted in which a cleaning device (not shown) is installed on the stand 412 and the cleaning device automatically cleans the nozzle tip by wiping, sucking, or blowing away the liquid material accumulated at the nozzle tip. If such a configuration is adopted, it is possible to automatically resume the application work after cleaning (i.e., execute the application process after cleaning). Alternatively, only an alert (described below) may be issued, prompting the user to remove the dispensing device and disassemble and clean it. That is, an alarm device may be provided that issues a visual or audible alert when adhesion of the liquid material to the detection surface is confirmed in STEP 503. For example, the application device 401 may be configured to issue an alert by sound emitted from a speaker (not shown), light emitted from a light-emitting device, or an alert displayed on the screen of a display device, or to issue a command signal to an external device connected by wire or wirelessly to notify the user of an abnormality.

[0042] The puddle detection method may be performed during the operation of transporting the substrate (the object 411) into or out of the coating position. Furthermore, the puddle detection method may be performed when a set execution timing condition (e.g., the number of coatings) is met, rather than every time the coating method is performed. For example, the puddle detection method may be performed every time a set number of coating operations, such as five or ten, are performed, or every time a set time period has elapsed. If the allowable amount of liquid puddle is large, productivity can be improved by setting the interval between the puddle detection steps longer than the standard execution interval to reduce the number of times the puddle detection step is performed. Furthermore, rather than determining that an unacceptable puddle has occurred when the puddle detection method detects adhesion of liquid material on the detection surface even once, the method may determine that an unacceptable puddle has occurred when the puddle detection method detects adhesion of liquid material multiple times (or three or more times) cumulatively or multiple times (or three or more times) consecutively. This makes it possible to prevent the coating operation from being stopped due to a temporarily large puddle or erroneous detection.

[0043] According to the liquid puddle detection method of the present embodiment described above, the occurrence of a liquid puddle exceeding the allowable range is determined based on whether or not liquid has adhered to the detection surface, enabling highly accurate determination without false detection. Furthermore, since the predetermined detection distance L can be easily adjusted, the allowable amount of liquid puddle can be flexibly changed depending on the application. For example, if the allowable amount of liquid puddle is small, the predetermined detection distance L can be set shorter than the standard value, and if the allowable amount of liquid puddle is large, the predetermined detection distance L can be set longer than the standard value. Furthermore, since the detection device can be mounted on a moving device that moves the discharge device relative to the application device to detect liquid puddles, there is no need to increase the size of the application device, and additional equipment can be minimized.

[0044] Although preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments, and such modifications and improvements are also included within the technical scope of the present invention. For example, in the embodiments, the dispensing device is described as a jet-dispensing type dispensing device (dispenser). However, the technical concept of the present invention can also be applied to dispensing devices (dispensers) using various dispensing methods, such as an air type that dispenses using air pressure or a screw type that dispenses using screw rotation. Furthermore, in the embodiments, the detection device is configured to be movable by a moving device, but the detection device may also be fixed. Furthermore, in the embodiments, the coating device 401 in which one discharge device 402 is provided on the Z drive device 406 is illustrated. However, the technical concept of the present invention can also be applied to an embodiment in which multiple discharge devices are provided on a relative drive device.

[0045] 101: liquid puddle detection device, 102, 402: discharge device, 103, 601, 701, 801: nozzle, 104: detection device, 105: movement device, 106: detection control device, 107: detection member, 107a, 602a, 702a: detection surface, 110, 603, 703, 804: liquid material, 401: application device, 403: relative drive device, 404: X drive device, 405: Y drive device, 406 : Z driving device, 407: X movement direction, 408: Y movement direction, 409: Z movement direction, 410: work table, 411: object to be coated (work), 412: stand, 413: coating control device, 414: measuring device, 415: calibration table, 417: cover, 418: conveying device, 419: rail, 420: conveying drive device, 421: conveying direction, 702: surface to be coated, 802: hole, 803: wall

Claims

1. A method for detecting a liquid puddle at the lower end of a nozzle of a liquid material ejection device, comprising: a first step of moving the nozzle to a detection position on a detection surface; a second step of lowering the nozzle until a predetermined detection distance is reached between the lower end of the nozzle and the detection surface, and then raising the nozzle when the predetermined detection distance is reached; and a third step of detecting the liquid puddle at the lower end of the nozzle by using a detection device to detect whether liquid material is adhering to the detection surface.

2. The method for detecting a liquid puddle at the lower end of a nozzle according to claim 1, wherein the liquid material is not discharged from the nozzle while the second step is being carried out.

3. A method for detecting a liquid accumulation at the bottom end of a nozzle according to claim 1, wherein the nozzle has one discharge port at the bottom end.

4. The method for detecting a liquid accumulation at the lower end of a nozzle according to claim 1, wherein the nozzle is a cylindrical or tapered nozzle.

5. The method for detecting a liquid pool at the bottom end of a nozzle according to claim 1, wherein the detection device is one of an imaging device, a laser displacement meter, and an ultrasonic sensor.

6. A method for detecting a liquid puddle at the lower end of a nozzle according to claim 1, wherein the detection surface is either the upper surface of a plate-shaped detection member, the upper surface of a tape-shaped member, or an unused area on the upper surface of a workpiece.

7. A method for detecting a liquid puddle at the bottom end of a nozzle according to claim 1, wherein the predetermined detection distance is set within a range of 1 / 2 to 2 times the outer diameter of the bottom end of the nozzle, or 1 / 3 to 7 times the diameter of the nozzle outlet.

8. A liquid material application method comprising: an application step of discharging liquid material from the nozzle onto a workpiece; and a liquid puddle detection step of performing a method for detecting a liquid puddle at the lower end of a nozzle according to any one of claims 1 to 7 before or after the application step.

9. A liquid material applying method according to claim 8, further comprising a step of cleaning the lower end of the nozzle when the liquid material is detected adhering to the detection surface in the liquid puddle detection step.

10. The liquid material applying method according to claim 9, further comprising a post-cleaning applying step of discharging the liquid material from the nozzle onto the workpiece after the cleaning is performed.

11. A liquid material application method as described in claim 8, further comprising: if an unacceptable amount of liquid accumulation is detected at the lower end of the nozzle during the liquid accumulation detection process, generating a visually or audibly recognizable alert, or sending a command signal to an external device to notify the abnormality, and halting execution of the application process.

12. A liquid material application method as described in claim 8, further comprising: a carrying-in process for carrying the workpiece to an application position, which is carried out before the application process; and a carrying-out process for carrying the workpiece out of the application position, which is carried out after the application process, wherein the liquid puddle detection process is carried out in parallel with either the carrying-in process or the carrying-out process.

13. A device for detecting a liquid puddle at the bottom end of a nozzle, comprising: a moving device that moves a discharge device having a nozzle onto a detection surface; a detection device that detects liquid material adhering to the detection surface; and a detection control device that controls the operation of the moving device and the detection device, wherein the detection control device executes the following steps: a first step in which the moving device moves the nozzle onto the detection surface; a second step in which the nozzle is lowered until a predetermined detection distance is reached between the bottom end of the nozzle and the detection surface, and then raised when the predetermined detection distance is reached; and a third step in which the detection device detects whether liquid material is adhering to the detection surface, thereby detecting a liquid puddle at the bottom end of the nozzle.

14. The device for detecting a liquid accumulation at the lower end of a nozzle according to claim 13, wherein the detection control device has a function for setting the predetermined detection distance.

15. The device for detecting a liquid accumulation at the lower end of a nozzle according to claim 13, wherein the moving device is capable of moving the detection device onto the detection surface.

16. A coating device comprising: a device for detecting liquid accumulation at the lower end of a nozzle as described in any one of claims 13 to 15; a discharge device having a nozzle; a work table for holding a work; a stand on which the work table is placed; a transport device for transporting the work to the work table; and a coating control device for controlling the operation of the discharge device and the moving device, wherein the coating device applies liquid to the work while moving the discharge device and the work relative to each other using the moving device based on a relative movement command from the coating control device.

17. The coating device according to claim 16, further comprising a cleaning device on the stand for cleaning the lower end of the nozzle, wherein the detection control device executes a fourth step of cleaning the lower end of the nozzle using the cleaning device when it detects in the third step that liquid material is adhering to the detection surface.

18. The coating device according to claim 16, further comprising an alarm device that generates a visually or audibly perceptible alert, wherein the detection control device executes a fourth step of generating the alert by the alarm device when it is detected in the third step that the liquid material is adhered to the detection surface.

19. The coating device according to claim 16, wherein the detection control device has a function for setting conditions relating to the timing of executing the first to third steps.

20. The coating device according to claim 16, wherein the discharge device is a flying discharge type dispenser that discharges droplets in flying fashion from the discharge opening of the nozzle.

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