Droplet discharge device and method for discharging droplet

Abstract

To suppress generation of mist and cause liquid to preferably adhere to an object.SOLUTION: A droplet discharge device includes: a discharge part 1 including a nozzle 24 for discharging a droplet 29 to an object 200; and a movement mechanism for relatively moving at least one of the object 200 and discharge part 1. The droplet discharge device controls an amount of one droplet 29 and an impact distance Px, Py of the droplet 29 in accordance with an incident angle α of the droplet 29 in a position where the droplet 29 impacts on the object 200.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a droplet ejection device and a droplet ejection method. [Background technology]

[0002] 2. Description of the Related Art Droplet ejection devices that eject droplets from a nozzle and deposit the liquid on a target object are known.

[0003] For example, Patent Document 1 (Japanese Patent No. 4792701) proposes a droplet ejection device that controls the timing of droplet ejection while moving the ejection head obliquely relative to the direction of the nozzle row in order to increase the resolution of the ejection position.

[0004] However, when droplets are ejected from an oblique direction relative to the surface of an object, some of the droplets ejected onto the object may bounce back and become mist, making it difficult to properly adhere the liquid to the object. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to suppress the generation of mist and ensure good adhesion of liquid to an object. [Means for solving the problem]

[0006] In order to solve the above problems, the droplet ejection device of the present invention comprises an ejection section having a nozzle that ejects droplets onto an object, and a moving mechanism that moves at least one of the object and the ejection section relatively, and is characterized in that the amount of each droplet and the landing interval of the droplets are controlled according to the incident angle of the droplet at the position where the droplet lands on the object. Effect of the Invention

[0007] According to the present invention, it is possible to suppress the generation of mist and to satisfactorily apply liquid to an object. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an overall configuration of a droplet ejection device according to a first embodiment of the present invention. [Diagram 2] 5A and 5B are diagrams showing a more specific configuration of a liquid supply unit according to the first embodiment of the present invention. [Diagram 3] FIG. 2 is a perspective view of a discharge portion according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view of a discharge portion according to the first embodiment of the present invention. [Diagram 5] 11 is a diagram showing a mode in which painting is performed with the nozzle surface of the discharge part inclined with respect to the surface of the object. FIG. [Figure 6] FIG. 11 is a diagram showing the relationship between the angle of incidence and the amount of mist. [Figure 7] 1A to 1C are diagrams illustrating a droplet ejection method according to a first embodiment of the present invention. [Figure 8] 1 is a block diagram showing a hardware configuration of a painting system according to a first embodiment of the present invention. FIG. [Figure 9] FIG. 4 is a diagram showing a flow of generating painting data according to the first embodiment of the present invention. [Figure 10] FIG. 2 is a diagram showing a painting flow according to the first embodiment of the present invention. [Figure 11] FIG. 4 is a block diagram showing another hardware configuration of the painting system. [Figure 12] FIG. 13 is a diagram showing a painting flow according to another hardware configuration. [Figure 13] 5A to 5C are diagrams illustrating a droplet ejection method according to a second embodiment of the present invention. [Figure 14] 13A and 13B are diagrams illustrating an example in which the incidence angle is different for each nozzle. [Figure 15] FIG. 13 is a diagram showing an example of a criterion for determining an incident angle. [Figure 16] FIG. 13 is a diagram showing the center of the nozzle arrangement range when the nozzles are arranged in a staggered pattern over two rows. [Figure 17]13 is a diagram showing a change in the spacing between nozzles in a direction perpendicular to the movement when a discharge section having nozzles arranged in a staggered pattern is tilted with respect to the movement direction X. FIG. [Figure 18] FIG. 1 is a block diagram of a control unit having a machine learning function. [Figure 19] 11A and 11B are diagrams showing examples of other droplet ejection devices to which the present invention can be applied. [Figure 20] FIG. 13 is a diagram showing an example of still another droplet ejection device to which the present invention can be applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are given the same reference numerals as far as they can be distinguished, and the description thereof will be omitted after it has been described once.

[0010] <Overall configuration of droplet ejection device> First, the overall configuration of a droplet ejection device according to a first embodiment of the present invention will be described with reference to FIG.

[0011] Here, as an example of a droplet discharge device, a coating device 100 that discharges droplets onto an automobile body, which is an object 200, to paint the automobile body, is illustrated. Note that the object 200 may be an aircraft body, a ship hull, or any other three-dimensional structure, in addition to an automobile body.

[0012] As shown in FIG. 1, a painting apparatus 100 according to a first embodiment of the present invention includes four painting robots 2.

[0013] Each painting robot 2 has a base 10 placed on a floor surface or the like, a first arm 11 provided on the base 10, a second arm 12 connected to the first arm 11, and a head unit 13 provided at the tip of the second arm 12. The first arm 11 and the second arm 12 of the painting robot 2 are robot arms rotatably and swingably connected via a joint, and function as a movement mechanism that moves the head unit 13 to a desired position by being driven in a rotational or swinging manner.

[0014] Specifically, the first arm 11 is provided to be rotatable in the direction of arrow A in Fig. 1 relative to the base part 10 and swingable in the direction of arrow B. The second arm 12 is provided to be rotatable in the direction of arrow C in Fig. 1 relative to the tip of the first arm 11 and swingable in the direction of arrow D. The head unit 13 is attached to be rotatable in the direction of arrow E in Fig. 1 relative to the tip of the second arm 12 and swingable in the direction of arrow F. The number of painting robots 2 is not limited to four, and may be one, two, three, five or more.

[0015] The head unit 13 has an ejection unit 1 that ejects droplets, and a position detection unit 3 that detects the position of the target object 200. The ejection unit 1 has a plurality of nozzles that eject droplets. The position detection unit 3 is attached to the tip of the second arm 12 integrally with the ejection unit 1. The position detection unit 3 includes, for example, a stereo camera that detects three-dimensional position information of three or more feature points on the target object 200. The stereo camera has a plurality of cameras. The position detection unit 3 acquires a distance image of the target object 200 by a triangulation method based on the parallax between images captured by the plurality of cameras.

[0016] Moreover, the coating apparatus 100 according to the first embodiment of the present invention includes a liquid supply unit 4 and a control unit 5 in addition to the coating robot 2.

[0017] The liquid supply unit 4 has a liquid storage unit 6 and an air supply unit 7. The liquid storage unit 6 is a tank that stores a liquid 8 such as paint inside. The air supply unit 7 is a compressor that supplies air to the liquid storage unit 6. When air is supplied from the air supply unit 7 to the liquid storage unit 6, the liquid storage unit 6 is pressurized, and the liquid 8 in the liquid storage unit 6 is supplied to the discharge unit 1 and is discharged from the nozzle of the discharge unit 1 as droplets. In addition to droplets, the discharge unit 1 can also discharge the liquid in a thread-like form. In addition, in FIG. 1, only a path through which the liquid 8 is supplied to one discharge unit 1 is shown, but the liquid 8 is supplied from the liquid storage unit 6 to all discharge units 1 in the same way. In addition, a plurality of liquid storage units 6 that store liquids of different colors or types may be prepared so that the color or type of liquid can be switched and supplied to each discharge unit 1.

[0018] The control unit 5 controls the operation of each painting robot 2 and the discharge operation of each discharge unit 1 based on the shape data of the object 200 and the coating image data input in advance, as well as the position information of the object 200 detected by each position detection unit 3. As a result, the head unit 13 is moved along the shape of the object 200, and droplets are discharged from the discharge unit 1 onto the surface of the object 200. Note that, although only a signal line from the control unit 5 to one painting robot 2 and one discharge unit 1, and a signal line from one position detection unit 3 to the control unit 5 are shown in FIG. 1, the control unit 5 controls the operation of all painting robots 2 and all discharge units 1, and receives detection signals from all position detection units 3.

[0019] FIG. 2 is a diagram showing a more specific configuration of the liquid supply section 4 according to the first embodiment of the present invention.

[0020] As shown in FIG. 2, the liquid supply unit 4 has a liquid storage unit 6, an air supply unit 7, and a plurality of air regulators 9. The air regulator 9 is provided in an air flow path 111 that connects the air supply unit 7 and the plurality of liquid storage units 6. The air regulator 9 adjusts the air pressure sent from the air supply unit 7 to each liquid storage unit 6. In addition, the plurality of liquid storage units 6 are individually connected to each discharge unit 1 via an air flow path 112. Therefore, when the inside of each liquid storage unit 6 is pressurized, the liquid 8 is supplied from each liquid storage unit 6 to each discharge unit 1. Note that the liquid storage unit 6 does not have to be provided for each discharge unit 1, and may be a single liquid storage unit provided in common to all the discharge units 1.

[0021] <Configuration of the discharge section> Next, the configuration of the discharge part 1 according to the first embodiment of the present invention will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a perspective view of the discharge part 1 according to the first embodiment of the present invention, and Fig. 4 is a cross-sectional view of the discharge part 1 according to the first embodiment of the present invention.

[0022] As shown in FIG. 3, the discharge section 1 has a housing 20, and a supply port 21 and a recovery port 22 provided in the housing 20.

[0023] As shown in FIG. 4, a plurality of discharge modules 23 are arranged in one or more rows inside the housing 20. Each discharge module 23 has a nozzle plate 25, a nozzle valve 26, a piezoelectric element 27, and a liquid flow path 28. The nozzle plate 25 is provided with a nozzle 24 for discharging droplets for each discharge module 23. The nozzle 24 is configured to be openable and closable by the nozzle valve 26. The piezoelectric element 27 is a driving means that expands and contracts when a voltage is applied to drive the nozzle valve 26 to open and close. The liquid flow paths 28 communicate with each other between the discharge modules 23, forming a common flow path. The liquid flow path 28 also communicates with the supply port 21 and the recovery port 22.

[0024] When liquid is supplied from the supply port 21 into the housing 20 with the valve of the recovery port 22 closed, the liquid flows into the liquid flow path 28 and is pressurized. At this time, if no voltage is applied to the piezoelectric element 27, the nozzle 24 is closed by the nozzle valve 26, so no droplets are ejected from the nozzle 24. On the other hand, when a voltage is applied to the piezoelectric element 27, the nozzle valve 26 is driven to open the nozzle 24, causing droplets to be ejected from the nozzle 24. Furthermore, any liquid not ejected from the nozzle 24 is discharged to the outside via the recovery port 22.

[0025] <Issues with mist generated during painting> Here, the mist generated during painting will be described using the configuration of the first embodiment of the present invention as an example.

[0026] In the configuration in which the painting robot 2 moves the discharge unit 1 and can discharge droplets at a desired angle as in the first embodiment of the present invention, the nozzle surface of the discharge unit 1 (which can also be called the nozzle plate 25 shown in FIG. 4) can be arranged parallel to the surface of the object 200, so that painting can be performed well. However, when painting a three-dimensional structure with a complex shape such as a car body, as shown in FIG. 5, there may be cases where painting must be performed with the nozzle surface 15 of the discharge unit 1 tilted relative to the surface 201 of the object 200. In such cases, some of the droplets 29 discharged to the object 200 may bounce back and become mist, making it difficult to adhere the liquid to the object 200 well. Therefore, in places where painting must be performed with the nozzle surface 15 tilted relative to the surface 201 of the object 200, mist may be generated, making it difficult to perform good painting, and the painting quality may deteriorate.

[0027] The amount of mist generated by the rebound of droplets varies depending on the angle of incidence of the droplets with respect to the surface of the target. The "angle of incidence" is the angle α shown in Fig. 5, and refers to the inclination of the landing direction of the droplet 29 or the normal direction of the nozzle face 15 with respect to the normal direction of the surface 201 of the target 200 at the position where the droplet 29 lands.

[0028] FIG. 6 shows the relationship between the angle of incidence and the amount of mist.

[0029] In FIG. 6, three graphs shown by a solid line, a dashed line, and a two-dot dashed line respectively show the relationship between the angle of incidence and the amount of mist when the amount (volume) of a droplet discharged from a nozzle is different. Of the three graphs, the solid line shows the largest amount of droplet, the dashed line shows the second largest amount, and the two-dot dashed line shows the smallest amount. According to the relationship shown in FIG. 6, in each case, the amount of mist tends to increase as the angle of incidence increases. Also, even with the same angle of incidence, the amount of mist is greater when the amount of droplet is large than when the amount is small. Therefore, the amount of mist changes depending on the amount of droplet as well as the angle of incidence, and more mist is generated when the angle of incidence increases, and more mist is generated even when the amount of droplet is large.

[0030] Thus, the amount of mist tends to increase as the angle of incidence increases or as the amount of liquid per drop increases. On the other hand, if we focus on this relationship, we can say that the amount of mist can be reduced by reducing the amount of liquid per drop. However, simply reducing the amount of liquid per drop reduces the amount of liquid discharged onto the target object, which can lead to new problems such as a thinner coating or exposure of the base.

[0031] Therefore, in the present invention, a droplet ejection method is proposed that can effectively deposit liquid on an object while suppressing mist. Hereinafter, a droplet ejection method according to a first embodiment of the present invention will be described.

[0032] <Droplet ejection method according to the first embodiment of the present invention> FIG. 7 is a diagram showing a droplet ejection method according to the first embodiment of the present invention.

[0033] 7A shows the tilt β (β1) of the nozzle row, the landing area S (S1) of the droplets 29, and the landing intervals Px, Py (Px1, Py1) of the droplets 29 when the incident angle α is α1 (e.g., 0°). Also, FIG. 7B shows the tilt β (β2) of the nozzle row, the landing area S (S2) of the droplets 29, and the landing intervals Px, Py (Px2, Py2) of the droplets 29 when the incident angle α is an angle α2 larger than the incident angle α1. Similarly, FIG. 7C shows the tilt β (β3) of the nozzle row, the landing area S (S3) of the droplets 29, and the landing intervals Px, Py (Px3, Py3) of the droplets 29 when the incident angle α is an angle α3 larger than the incident angle α2. In addition, in each of Figures 7(a), (b), and (c), the <incident angle> diagram is a side view of the discharge section 1 seen from the side, the <inclination of the nozzle row> diagram is a plan view of the discharge section 1 seen from above, and the <landing area / landing interval> diagram is a plan view of the landing points of droplets 29 on the surface 201 of the target object 200 seen from above.

[0034] The "tilt β of the nozzle row" is the tilt of the arrangement direction of the nozzles 24 with respect to the moving direction X of the discharge unit 1 when the discharge unit 1 moves along the surface 201 of the target object 200. When the nozzles 24 are arranged in a pattern other than a single row, such as a staggered or lattice pattern, the direction in which the nozzles 24 are arranged the longest is regarded as the arrangement direction of the nozzles 24.

[0035] The "landing area S of droplet 29" is the area where one droplet 29 lands on the surface 201 of the target 200. Also, the "landing intervals Px, Py of droplet 29" are the landing intervals between adjacent droplets 29, and include the landing interval Px in the movement direction X of the discharge unit 1 and the landing interval Py in the movement perpendicular direction Y that is perpendicular to the movement direction X.

[0036] As shown in FIG. 7, in the first embodiment of the present invention, the landing area S of the droplet 29 is made smaller (S1>S2>S3) as the incident angle α increases (α1<α2<α3). That is, since mist is more likely to be generated when the incident angle α increases (FIG. 6), when the incident angle α is large, the amount of liquid per droplet is reduced so that the landing area S of the droplet 29 is smaller. The amount of the droplet 29 can be adjusted by changing any one or two or more of the opening time of the nozzle 24, the opening amount of the nozzle 24, and the discharge pressure of the droplet 29 by the nozzle valve drive control unit 402 in FIG. 8. Therefore, when the incident angle α is large, the amount of the droplet 29 is reduced by shortening the opening time of the nozzle 24, reducing the opening amount of the nozzle 24, reducing the discharge pressure of the droplet 29, or by performing two or more of these. This reduces the amount of mist.

[0037] Furthermore, simply reducing the amount of droplets 29 reduces the amount of liquid discharged onto the target object 200, so in the first embodiment of the present invention, when the incident angle α is large, the landing intervals Px, Py of the droplets 29 are also reduced (Px1>Px2>Px3, Py1>Py2>Py3). In this case, both the landing interval Px in the movement direction X and the landing interval Py in the direction perpendicular to the movement Y are reduced.

[0038] The landing interval Px in the moving direction X can be adjusted by changing at least one of the moving speed of the discharging unit 1 when it moves by the robot control device 600 in Fig. 8 and the time interval at which adjacent droplets 29 in Fig. 7 are discharged from the discharging unit 1 by the head control device 500 in Fig. 8. Therefore, when the incidence angle α is large, the landing interval Px in the moving direction X can be reduced by slowing down the moving speed of the discharging unit 1, shortening the time interval at which the droplets 29 are discharged, or by performing both of these (Px1>Px2>Px3). Note that, even when the number of nozzles 24 is single instead of multiple, the landing interval Px in the moving direction X can be adjusted by doing the same.

[0039] On the other hand, the landing interval Py in the direction perpendicular to the movement Y can be changed by changing the inclination β of the nozzle row, as shown in Fig. 7. Therefore, when the incident angle α is large, the landing interval Py in the direction perpendicular to the movement Y can be reduced (Py1>Py2>Py3) by having the robot control device 600 control the orientation of the discharge unit 1 to reduce the inclination β of the nozzle row (β1>β2>β3).

[0040] As described above, in the first embodiment of the present invention, when the incident angle α is large, the head control device 500 reduces the amount of each droplet 29 and reduces the landing intervals Px, Py of the droplets 29 to eject the droplets 29. As a result, when the incident angle α is large, even if the landing area S of one droplet 29 becomes small as a result of reducing the amount of each droplet 29 to suppress mist, the landing intervals Px, Py between the droplets 29 can be reduced to ensure the amount of liquid attached per unit area. Therefore, according to the first embodiment of the present invention, the base is not exposed and the thickness of the coating film can be satisfactorily secured, so that it is possible to suppress mist and achieve good liquid attachment, thereby improving the coating quality.

[0041] In the first embodiment of the present invention, the landing intervals Px, Py are small in both the movement direction X and the direction perpendicular to the movement Y of the discharge part 1, but it is also possible to reduce the landing interval in only one of them. Even in this case, the amount of liquid attached per unit area can be increased, so improvement in coating quality can be expected. Note that, in order to more reliably prevent coating defects and improve coating quality, it is preferable to reduce the landing intervals Px, Py in both the movement direction X and the direction perpendicular to the movement Y.

[0042] In the first embodiment of the present invention, as shown in FIG. 7, the landing area S and landing intervals Px, Py are changed in two stages, from (a) to (b) and from (b) to (c), as the incident angle α increases, but a single change may be used. That is, in both cases where the incident angle α is (b) larger than (a) and where the incident angle α is (c) larger than (a), the landing area S and landing intervals Px, Py may be changed to only one stage, for example, to the state (c). Even in such a case, the amount of liquid attached per unit area can be secured while suppressing mist. However, when the incident angle α is (b), if the landing area S and landing intervals Px, Py are changed to the state (c), the coating area per unit time will be smaller than when the landing area S and landing intervals Px, Py are in the state (b), and there is a concern that the coating time will be longer. Therefore, in order to perform coating efficiently while ensuring coating quality, it is preferable to change the landing area S and the landing intervals Px, Py in two or more stages according to the magnitude of the incident angle α, as in the first embodiment of the present invention.

[0043] <Hardware configuration of the painting system> FIG. 8 is a block diagram showing a hardware configuration of the painting system according to the first embodiment of the present invention.

[0044] 8, the painting system 1000 according to the first embodiment of the present invention includes, in addition to multiple painting robots 2, an input device 700, a computer 300, a controller 400, a head control device 500, and a robot control device 600. Note that only two painting robots 2 are shown here, and the remaining painting robots 2 are omitted.

[0045] Each painting robot 2 has an encoder sensor 16 and a robot driving unit 17. The encoder sensor 16 is an optical sensor that optically detects slits of an encoder provided at the connecting portion between the base portion 10 and the first arm 11 of the painting robot 2, the connecting portion between the first arm 11 and the second arm 12, and the connecting portion between the second arm 12 and the head unit 13. The detection by the encoder sensor 16 makes it possible to grasp the amount of rotation and the amount of swing of each of the first arm 11, the second arm 12, and the head unit 13, so that three-dimensional position information of the head unit 13 can be obtained. The robot driving unit 17 is a driving unit that performs the rotational and swinging operations of the first arm 11, the second arm 12, and the head unit 13.

[0046] The input device 700 is a device into which information such as shape data of the object 200, painting image data, coordinate data, painting mode, painting range (painting start position, painting end position), painting instructions, etc. is input. The input device 700 has a keyboard, mouse, touch panel, etc., for a user to perform input operations. The various information inputted by the input device 700 is sent to the computer 300.

[0047] The computer 300 has a RIP (Routing Information Protocol) unit 301 that performs image processing of image data received from the input device 700, and a rendering unit 302 that breaks down the image data into painting data for each scan of the head unit 13. The computer 300 also receives shape data of the object 200 from the input device 700, acquires actual position information of the object 200 detected by the position detection unit 3, and generates a painting route for the painting robot 2 based on the shape data and actual position information of the object 200. The computer 300 also calculates an incidence angle α of droplets with respect to the object 200 on the generated painting route. The incidence angle α is calculated using any one or a combination of the shape data of the object 200 received from the input device 700, the position information of the object 200 detected by the position detection unit 3, and the three-dimensional position information of the head unit 13 detected by the encoder sensor 16.

[0048] The controller 400, the head control device 500, and the robot control device 600 function as a control unit 5 that controls the operation of each painting robot 2 and the discharge operation of each discharge unit 1. In this case, one head control device 500 and one robot control device 600 are provided, but the head control device 500 and the robot control device 600 may be provided individually for each painting robot 2.

[0049] The controller 400 includes a system control unit 401, a nozzle valve drive control unit 402, a discharge cycle signal generating unit 403, a memory control unit 404, a data storage unit 405, and a robot control signal generating unit 406. The system control unit 401 receives painting data and command signals from the computer 300 and controls the overall operation of the painting system 1000. The system control unit 401 may also include the functions of the RIP unit 301 and the rendering unit 302 of the computer 300. The nozzle valve drive control unit 402 generates a control signal for controlling the opening and closing drive of the nozzle valve 26 based on the painting data and the incident angle α received from the computer 300. The discharge cycle signal generating unit 403 generates a discharge cycle signal for the discharge unit 1 based on the output signal from the encoder sensor 16 and the painting data and the incident angle α received from the computer 300. The memory control unit 404 controls the data storage unit 405. The data storage unit 405 includes memories such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a HDD (Hard Disk Drive), and stores the painting data and painting area data received from the computer 300. The robot control signal generation unit 406 generates a synchronization control signal that coordinates the drive of each painting robot 2 with the droplet discharge operation, based on the painting data and painting route information from the computer 300. In addition, the robot control signal generation unit 406 generates a control signal that determines the inclination β of the nozzle row of the discharge unit 1, based on the incident angle α calculated by the computer 300.

[0050] The head control device 500 receives a control signal from the nozzle valve drive control unit 402 and a discharge cycle signal from the discharge cycle signal generation unit 403, and controls the discharge amount and discharge timing of the discharge unit 1 based on the received control signal and discharge cycle signal. At this time, the discharge amount and discharge timing of the discharge unit 1 are controlled based on the incident angle α, so that the amount of discharged droplets and the landing interval Px in the movement direction X are controlled to the amount of droplets and the landing interval according to the incident angle α.

[0051] The robot control device 600 receives a control signal from the robot control signal generation unit 406, and controls the driving of the robot driving unit 17 based on the received synchronous control signal. At this time, the robot driving unit 17 is controlled based on the incident angle α, whereby the inclination β of the nozzle row of the discharge unit 1 is controlled, and the landing interval Py in the direction perpendicular to the movement Y is controlled to the landing interval according to the incident angle α.

[0052] <Painting data generation flow> Next, a flow of generating painting data according to the first embodiment of the present invention will be described with reference to FIG.

[0053] 9, when the generation of painting data is started, the computer 300 reads data related to the object 200 from the input device 700, and generates painting data for each of the read data. As a result, the operation of the painting robot 2 and the discharging operation of the discharging unit 1 are set based on the painting data.

[0054] Further, the computer 300 calculates the incident angle α of the droplets with respect to the target object 200 based on the painting data. As a result, if there is a painting location where the incident angle α is equal to or greater than a preset threshold value T, the painting data is modified so that the amount of droplets discharged at that painting location is reduced and the landing interval is shortened. In other words, when the amount of droplets and the landing interval are changed, the operation of the painting robot 2 and the discharge operation of the discharge unit 1 are changed, and the painting data is modified according to the changed operation. On the other hand, for a painting location where the incident angle α is less than the threshold value T, the amount of droplets discharged and the landing interval are not changed, and the already generated painting data is used. In this manner, the generation of the painting data is completed.

[0055] <Painting flow> Next, a painting flow according to the first embodiment of the present invention will be described with reference to FIG.

[0056] 10, when painting starts, the controller 400 acquires painting data generated by the computer 300. Next, the controller 400 controls the painting robot 2 based on the acquired painting data, and the painting robot 2 moves the discharge unit 1 to the part of the target object 200 to be painted.

[0057] Then, the controller 400 checks the incident angle α at the coating location from the acquired coating data. As a result, when the incident angle α is less than a predetermined threshold T, the droplets are discharged, for example, in the manner shown in FIG. 7(a). On the other hand, when the incident angle α is equal to or greater than the predetermined threshold T, the droplets are discharged so that the amount of droplets discharged is reduced and the landing interval is shortened, compared to when the incident angle α is less than the threshold T. For example, the droplets are discharged in the manner shown in FIG. 7(b) or (c). Thereafter, the controller 400 similarly checks the incident angle α for each coating location to which the discharge unit 1 moves, and controls the amount of each droplet and the landing interval of the droplets according to the incident angle α.

[0058] <Other hardware configurations> FIG. 11 is a block diagram showing another hardware configuration of the painting system.

[0059] The hardware configuration of the coating system according to the present invention may be a hardware configuration as shown in Fig. 11. The hardware configuration shown in Fig. 11 differs from the example shown in Fig. 8 in that the position detection unit 3 detects the position information of the target object 200 in real time, and the detected position information is directly input to the head control device 500 and the robot control device 600 without going through the computer 300.

[0060] In this case, as shown in Fig. 12, when painting starts, first, the controller 400 acquires painting data generated by the computer 300. Note that the flow of generating the painting data is the same as the flow in Fig. 9, so a description thereof will be omitted. Next, the controller 400 controls the painting robot 2 based on the acquired painting data, and the painting robot 2 moves the discharge unit 1 to the part of the target object 200 to be painted.

[0061] When the discharge unit 1 moves to a coating location on the target object 200, position information of the coating location is acquired in real time by the position detection unit 3, and the acquired position information is directly input to the head control device 500 and the robot control device 600. The head control device 500 and the robot control device 600 then control the operation of the painting robot 2 and the discharge unit 1 based on the input position information. At this time, when the incidence angle α at the coating location is equal to or greater than a predetermined threshold value T, the amount of droplets discharged is reduced and droplets are discharged with a shorter landing interval than when the incidence angle α is less than the threshold value T. Thereafter, the amount of droplets and the landing interval of droplets are controlled in the same manner according to the incidence angle α for each coating location to which the discharge unit 1 moves.

[0062] Second embodiment of the present invention FIG. 13 shows a droplet ejection method according to a second embodiment of the present invention.

[0063] 13, as the incident angle α increases from α1 to α2, α3, and α4, the head control device 500 controls the discharge amount and discharge interval of the discharge unit 1, and the robot control device 600 controls the orientation of the discharge unit 1 to change the landing area S and landing intervals Px and Py of the droplets 29 in three stages according to the incident angles α2 to α4. Therefore, the inclination β of the nozzle row is also changed in three stages from β1 to β2, β3, and β4. In this way, by changing the landing area S and landing intervals Px and Py in three stages according to the incident angles α2 to α4, it is possible to perform more efficient coating while maintaining the coating quality.

[0064] 13(a), when the incident angle α is 0°, the nozzle row is arranged at an angle of 90° with respect to the moving direction X of the discharge unit 1. In this manner, when the incident angle α is 0°, the inclination β of the nozzle row may be 90°. By making the inclination β of the nozzle row 90°, it is possible to ensure a large landing interval Py, particularly in the direction perpendicular to the movement Y, and therefore efficient coating can be performed.

[0065] In short, in the present invention, in both the embodiment of FIG. 7 and the embodiment of FIG. 13, when the incident angle α is a predetermined angle larger than 0° (other than (a) in FIG. 7 and FIG. 13), the discharge unit 1 is tilted with respect to the moving direction X to discharge the droplets 29 from the nozzle 24. That is, in the cases of (b) and (c) in FIG. 7 and (b), (c), and (d) in FIG. 13, the droplets 29 are discharged so that the interval Py between the droplets 29 that land adjacent to each other on the coating surface of the target object 200 in the orthogonal moving direction Y is smaller than the interval G (FIG. 7, FIG. 13) between the nozzles 24 that discharge the droplets 29 in the arrangement direction, and the droplets 29 that land adjacent to each other overlap each other. This ensures the amount of liquid attached per unit area, and improves the coating quality.

[0066] Note that the above "distance G in the arrangement direction between the nozzles 24 that eject droplets 29" refers to the distance in the arrangement direction between the nozzles 24 that are arranged adjacent to each other in the nozzles 24 that actually eject droplets. Therefore, when droplets 29 are ejected from only some of the nozzles 24, the distance Py in the perpendicular movement direction Y between the droplets 29 that land adjacent to each other is set to be smaller than the distance G in the arrangement direction between the nozzles 24 that are arranged adjacent to each other in the some of the nozzles 29.

[0067] <Criteria for determining the angle of incidence> Next, an example of a criterion for determining the incidence angle α will be described.

[0068] 14, when the surface 201 of the target object 200 is a curved surface, the incidence angles α1 to α4 of the nozzles 24 may differ. In such a case, since the inclination β of the nozzle row cannot be changed for each of the incidence angles α1 to α4, it is necessary to determine an incidence angle α0 that serves as a reference for setting the inclination β of the nozzle row.

[0069] 14 is used as a reference, the amount of droplets is determined based on the smallest incidence angle α1 of the four, and therefore the amount of droplets may be set insufficient to suppress mist for the rightmost nozzle 24 with the largest incidence angle α4. In other words, if the incidence angle of one of the nozzles 24 arranged at both ends is used as a reference, the deviation (absolute value) from the other incidence angle becomes large, and the amount of droplets cannot be made sufficiently small for the other nozzle, which may result in mist generation.

[0070] Therefore, when the incidence angle α differs for each nozzle 24, it is preferable to determine the incidence angle α0 based on the center m of the arrangement range H of the nozzles 24 as a reference, as shown in Fig. 15. This reduces the maximum deviation (absolute value) between the reference incidence angle α0 and the incidence angles α1 and α4 at both ends, making it difficult for mist to occur.

[0071] The position of the reference incident angle α0 is not limited to the center m of the arrangement range H of the nozzles 24, and other positions may be used as the reference. For example, if the incident angle is always large at the position of one of the nozzles 24 at one end among the nozzles 24 at both ends, the incident angle α0 may be determined based on the position of the nozzle 24 at that end. Also, if only some of the nozzles 24 eject droplets, the incident angle α0 may be determined based on the center position of the arrangement range of the nozzles 24 that actually eject droplets. How the reference incident angle α0 is determined can be changed as appropriate depending on the shape of the target object 200, the arrangement of the nozzles 24, etc.

[0072] Furthermore, when the nozzles 24 are arranged in a staggered pattern across two rows as in the example shown in FIG. 16, the center m of the arrangement range H of the nozzles 24 may be set as the intersection of the diagonals of a parallelogram in which the nozzles 24 are arranged, and the incidence angle α0 may be determined based on the position of this intersection.

[0073] In addition, when the nozzles 24 are arranged in a staggered manner, if the discharge part 1 tilts with respect to the moving direction X, as in the transition from the state (a) to the state (b) shown in Fig. 17, the intervals V1, V2 between the nozzles 24 in the moving perpendicular direction Y will no longer be equal. In this case, the intervals between the droplets discharged from each nozzle 24 in the moving perpendicular direction Y will also no longer be uniform, which may result in a deterioration in coating quality.

[0074] Therefore, in the discharge unit 1 in which the nozzles 24 are arranged in a staggered manner, when the discharge unit 1 discharges droplets while being tilted with respect to the moving direction X, it is preferable to discharge droplets from either the upper or lower row of nozzles 24 (one row) of the nozzles 24 arranged in two rows, upper and lower, in FIG. 17. In this case, it is preferable that the reference incident angle α0 is determined based on the center of the arrangement range of the nozzles 24 in the upper and lower rows from which droplets are actually discharged. Also, in the case where droplets are discharged from only some of the nozzles 24 in the upper or lower row, the range from the nozzle 24 at one end to the nozzle 24 at the other end of the nozzles 24 that actually discharge droplets is set as the arrangement range, and the incident angle α0 may be determined based on the center of the arrangement range.

[0075] Even if droplets are ejected only from the nozzles 24 in one of the two upper and lower rows, the reference incident angle α0 may be determined based on the center m of the nozzle arrangement range H shown in Fig. 16. The reference incident angle α0 may also be determined based on the center of the arrangement range of the nozzles 24 in a row different from the row from which droplets are actually ejected.

[0076] Furthermore, when the incidence angle α of some of the nozzles 24 is very large, even if the incidence angle α0 is determined based on the center m of the arrangement range H of the nozzles 24, it may not be possible to effectively suppress the mist of droplets ejected from some of the nozzles 24. Therefore, when the incidence angle α of some of the nozzles 24 exceeds a predetermined value set in advance, the ejection of droplets from those nozzles 24 may be stopped. This makes it possible to prevent the generation of mist.

[0077] The predetermined value of the incidence angle α, which is the criterion for determining whether or not to eject a droplet, need not be a fixed value set in advance, but may be a value that is updated by machine learning.

[0078] <Machine learning configuration> FIG. 18 is a block diagram of the control unit 5 having a machine learning function.

[0079] 18 includes a data accumulation unit 85, a learning unit 86, and an estimation unit 87. The functions of the data accumulation unit 85, the learning unit 86, and the estimation unit 87 may be realized by a machine learning program implemented in the control unit 6.

[0080] The data storage unit 85 stores data including at least the shape data of the target object, the incidence angle α, the amount of ejected droplets, the inclination β of the nozzle array, the landing intervals Px, Py, and the amount of mist.

[0081] The learning unit 86 extracts the amount of mist at a given incidence angle α based on the data stored in the data storage unit 85, and learns the relationship between the incidence angle α, the amount of droplets ejected, and the inclination β of the nozzle row.

[0082] The learning unit 86 may, for example, use a data set stored in the data accumulation unit 85 that corresponds the incidence angle α, the amount of droplets ejected, and the inclination β of the nozzle array as teacher data to generate a trained model 88 that has learned the relationship between the incidence angle α, the amount of droplets ejected, and the inclination β of the nozzle array, and store the trained model in the estimation unit 87.

[0083] The algorithm used by the learning unit 86 is not particularly limited, and deep learning using a neural network, an unsupervised learning model, a supervised learning model, a reinforcement learning model, etc. can be applied.

[0084] The estimation unit 87 estimates a predetermined value of the incidence angle α, which is a criterion for determining whether or not to eject droplets, based on the learning by the learning unit 86. For example, when a value indicating an allowable amount of mist generation is input, the estimation unit 87 inputs the input value to the trained model 88 and estimates the predetermined value of the incidence angle α to be output from the trained model 88.

[0085] The control unit 5 controls the amount of droplets discharged from the discharge unit 1 and the inclination β of the nozzle array based on the predetermined value of the incident angle α estimated by the estimation unit 87.

[0086] By equipping the liquid ejection device according to the present invention with the control unit 5 shown in FIG. 18, it becomes possible to adjust the amount of droplets ejected from the ejection unit 1 and the inclination β of the nozzle array using a trained model based on machine learning.

[0087] <Other Examples of Droplet Discharge Devices> The present invention is also applicable to a droplet ejection device having the following configuration.

[0088] 19 shows an example of a coating apparatus 800 that performs coating by moving the object 200 instead of the discharge unit 1. In this case, the coating apparatus 800 includes a robot arm 90 that holds and moves the object 200, and a discharge unit 1 that is fixed to a support table or the like. While moving the object 200 by the robot arm 90, the liquid is discharged from the discharge unit 1 onto the object 200, thereby coating the object 200 with the liquid. Note that the "movement" of the object 200 includes not only a case where the object 200 is moved linearly or curvedly, but also a case where the object 200 is rotated to change its orientation relative to the discharge unit 1, thereby moving the surface of the object 200.

[0089] Even in the coating device 800 configured as described above, if the incident angle α between the object 200 and the discharge unit 1 is large, mist may be generated and good coating may not be performed. Therefore, if the incident angle α is large, it is preferable to reduce the amount of droplets (reduce the landing area) and reduce the landing interval of the droplets, as in each embodiment of the present invention. This makes it possible to suppress mist and perform good coating.

[0090] Furthermore, the moving mechanism provided in the coating apparatus according to the present invention is not limited to a moving mechanism that moves either the target object 200 or the discharge unit 1 relative to the other, but may be a moving mechanism that relatively moves both the target object 200 and the discharge unit 1. Furthermore, the moving mechanism is not limited to a robot arm, but may be a linear actuator that linearly moves at least one of the target object 200 and the discharge unit 1 in one direction or in two or three directions perpendicular to each other.

[0091] Furthermore, the discharge part 1 according to the present invention is not limited to one including a nozzle plate 25 provided with a nozzle 24 as shown in Fig. 4. For example, the present invention is also applicable to a coating device 900 having a configuration in which a nozzle 24 protrudes from the discharge part 1 as shown in Fig. 20. In this case, the nozzle surface described above is the tip surface 24a of the nozzle 24 or the outer surface 1a of the main body of the discharge part 1.

[0092] The present invention is also applicable to painting for purposes other than coloring and designing the body of an automobile. For example, the painting process of an automobile body includes undercoating for the purpose of ensuring adhesion and rust resistance of the coating film to the body substrate, intermediate coating for the purpose of ensuring impact resistance and durability, and topcoating for coloring and designing. The coating device according to the present invention may be used for undercoating or intermediate coating in addition to topcoating. In addition, if there is a coating process of a protective layer such as a clear layer applied for the purpose of gloss and protection of the coating film after the topcoating process, the coating device according to the present invention may be used in the coating process of the protective layer. Furthermore, if a peelable protective layer is applied to protect the painted surface after the shipment of the automobile or in the factory, the coating device according to the present invention can also be used for the coating of the protective layer. The peelable protective layer may be any layer that can be attached to the painted surface of the automobile body and chemically or physically protect the painted part from dust, metal powder, oil, salt, acid, ultraviolet rays, etc., and is preferably formed of a material mainly composed of an acrylic copolymer agent.

[0093] The present invention can also be applied to a droplet ejection device that ejects droplets for purposes other than painting, such as a marking device that ejects droplets onto an object to mark a specific location.

[0094] The present invention is not limited to a droplet ejection device that ejects droplets onto a three-dimensional structure such as a car body or building material, but can also be applied to a droplet ejection device that ejects droplets onto a planar object such as a plate or sheet. Even if the object is planar, if the surface is curved, the angle of incidence of the droplets with respect to the surface of the object may change, so by applying the present invention, it becomes possible to successfully attach the liquid to the object while suppressing mist. In addition, even if the surface of the object is flat, it is preferable to apply the present invention when droplets must be ejected with the nozzle surface inclined relative to the surface of the object. In addition, the "droplet ejection device" according to the present invention may include a means for transporting the object, a pre-processing device, and a post-processing device.

[0095] To summarize the above-described aspects of the present invention, the present invention includes at least the following aspects.

[0096] [First aspect] The first aspect is a droplet ejection device comprising an ejection section having a nozzle for ejecting droplets onto an object, and a movement mechanism for relatively moving at least one of the object and the ejection section, and which controls the amount of each droplet and the landing interval of the droplets depending on the incident angle of the droplet at the position where the droplet lands on the object.

[0097] [Second aspect] In a second aspect of the present invention, in the first aspect, the inclination of the nozzle arrangement direction with respect to the relative movement direction between the target object and the discharge portion is changed to control the landing interval of the droplets.

[0098] [Third aspect] A third aspect is the droplet ejection device according to the first or second aspect, wherein the droplet ejection device controls the landing intervals of the droplets by changing a relative moving speed between the target object and the ejection unit.

[0099] [Fourth aspect] A fourth aspect is any one of the first to third aspects, in which the time interval at which the droplets are discharged is changed to control the landing interval of the droplets.

[0100] [Fifth aspect] A fifth aspect is any one of the first to fourth aspects, in which the amount of each droplet of the droplet is controlled by changing an opening time of the nozzle or an opening amount of the nozzle.

[0101] [Sixth aspect] A sixth aspect is any one of the first to fifth aspects, wherein the amount of each of the droplets is controlled by changing the ejection pressure of the droplets.

[0102] [Seventh aspect] A seventh aspect is any one of the first to sixth aspects, wherein the amount of each of the droplets and the landing interval of the droplets are changed in two or more stages according to the incident angle.

[0103] [Eighth aspect] An eighth aspect is any one of the first to seventh aspects, wherein the incident angle is determined based on the center of an arrangement range of the nozzles.

[0104] [Ninth aspect] A ninth aspect is any one of the first to eighth aspects, wherein when the incident angle at the position of some of the nozzles exceeds a predetermined value, the ejection of the droplets from the some of the nozzles is stopped.

[0105] [Tenth aspect] A tenth aspect is a droplet ejection device comprising an ejection section having a plurality of nozzles that eject droplets onto an object, and a movement mechanism that moves at least one of the object and the ejection section relatively, wherein when the angle of incidence of the droplets at the position where the droplets land on the object is a predetermined angle greater than 0°, the ejection section ejects the droplets such that the distance between adjacent droplets that land is smaller than the distance in the arrangement direction between the nozzles that eject the droplets, and such that portions of the adjacent droplets that land overlap.

[0106] [Eleventh aspect] An eleventh aspect is a droplet ejection method for ejecting droplets from a nozzle onto a target object, in which the amount of each droplet and the landing interval of the droplets are controlled according to the incident angle of the droplet at the position where the droplet lands on the target object, thereby ejecting the droplets. [Explanation of symbols]

[0107] 1 Discharge part 2. Painting robot 11 First arm (movement mechanism) 12 Second arm (movement mechanism) 29 Droplets 90 Robot arm (movement mechanism) 100 Painting device (droplet ejection device) 200 Objects α angle of incidence β Nozzle row inclination H Nozzle arrangement range m center Px Interval of bullets in the direction of movement Py Interval between bullets perpendicular to the movement S Impact area X direction of movement Y Movement perpendicular direction [Prior art documents] [Patent documents]

[0108] [Patent Document 1] Patent No. 4792701

Claims

1. A discharge unit having a nozzle for discharging droplets onto a target object; a moving mechanism that relatively moves at least one of the target object and the discharge unit; Equipped with A droplet ejection device, comprising: a droplet ejection unit that controls a volume of each of the droplets and an interval between droplets landing on the target object according to an incident angle of the droplets at a position where the droplets land on the target object.

2. The droplet ejection device according to claim 1 , wherein the landing intervals of the droplets are controlled by changing an inclination of an arrangement direction of the nozzles with respect to a relative movement direction between the target object and the ejection unit.

3. The droplet ejection device according to claim 1 , wherein the landing interval of the droplets is controlled by changing a relative moving speed between the target object and the ejection unit.

4. The droplet ejection device according to claim 1 , wherein the time interval at which the droplets are ejected is changed to control the landing interval of the droplets.

5. The droplet ejection device according to claim 1 , wherein the amount of each droplet is controlled by changing an opening time of the nozzle or an opening amount of the nozzle.

6. The droplet ejection device according to claim 1 , wherein the amount of each droplet is controlled by changing the ejection pressure of the droplets.

7. 2. The droplet ejection device according to claim 1, wherein the amount of each of the droplets and the landing interval of the droplets are changed in two or more stages according to the incident angle.

8. The droplet ejection device according to claim 1 , wherein the incident angle is determined based on the center of an arrangement range of the nozzles.

9. The droplet ejection device according to claim 1 , wherein when the incident angle at the position of a portion of the nozzles exceeds a predetermined value, ejection of the droplets from the portion of the nozzles is stopped.

10. A discharge unit having a plurality of nozzles for discharging droplets onto a target object; a moving mechanism that relatively moves at least one of the target object and the discharge unit; Equipped with A droplet ejection device characterized in that, when the angle of incidence of the droplet at the position where the droplet lands on the target object is a predetermined angle greater than 0°, the ejection section ejects the droplets so that the distance between adjacent droplets that land is smaller than the distance in the arrangement direction between the nozzles that eject the droplets, and so that portions of the adjacent droplets that land overlap.

11. A droplet ejection method for ejecting droplets from a nozzle onto a target, comprising the steps of: A droplet ejection method, comprising the steps of: ejecting the droplets by controlling the amount of each droplet and the landing interval of the droplets according to an incident angle of the droplets at a position where the droplets land on the target object.

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