Liquid discharge device and liquid discharge method

Abstract

To provide a liquid discharge device and a liquid discharge method capable of forming a surface to be coated having a smooth edge part along a scanning direction while suppressing the generation of streaks on an area to be coated.SOLUTION: A liquid discharge device is the liquid discharge device which has a liquid discharge head provided with a plurality of nozzles and discharges the liquid while relatively moving the object or the liquid discharge head. Therein, the plurality of nozzles include a first nozzle which discharges the liquid in a liquid droplet shape and a second nozzle which discharges liquid continuously discharged in a liquid droplet shape. It is characterized that the second nozzle is arranged on the end part side of the liquid discharge head, of the plurality of nozzles in such a direction as to intersect with the direction of the relative movement.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus and a liquid ejection method. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as a device for discharging liquid onto a target object such as an automobile body part, a configuration having a liquid discharge head equipped with a plurality of nozzles has been disclosed (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0003] However, with the technology of Patent Document 1, it is difficult to simultaneously form a coating surface in which the occurrence of streaks is suppressed and a coating surface having smooth edges along the scanning direction.

[0004] The present invention has been made in consideration of the above, and aims to provide a liquid ejection device and a liquid ejection method that are capable of forming a coated surface with smooth edges along the scanning direction while suppressing the occurrence of streaks in the coated area. [Means for solving the problem]

[0005] A liquid ejection device according to one aspect of the disclosed technology has a liquid ejection head equipped with a plurality of nozzles that ejects liquid onto an object, and ejects the liquid by moving the object or the liquid ejection head relatively to one another, wherein the plurality of nozzles include a first nozzle that ejects the liquid in the form of droplets, and a second nozzle that ejects the liquid continuously, and the second nozzle is positioned toward the end of the liquid ejection head among the plurality of nozzles that eject the liquid in a direction intersecting the direction of the relative movement. Effect of the Invention

[0006] According to the present invention, it is possible to provide a liquid ejection device and a liquid ejection method that are capable of forming a coated surface having smooth edges along the scanning direction while suppressing the occurrence of streaks in a coated area. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of the overall configuration of a liquid ejection device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration example of a head according to the first embodiment. [Diagram 3] 2 is a cross-sectional view of a configuration example of a head according to the first embodiment. FIG. [Figure 4] FIG. 2 is a diagram illustrating a configuration example of a supply unit according to the first embodiment. [Diagram 5] FIG. 4 is a diagram showing an example of one scan of the head according to the first embodiment. [Figure 6A] 2 is a block diagram showing an example of a hardware configuration of a controller included in the liquid ejection device according to the first embodiment. FIG. [Figure 6B] 2 is a block diagram showing an example of a functional configuration of the liquid ejection device according to the first embodiment. FIG. [Figure 7] 1A to 1D are diagrams illustrating how a liquid ejection device according to the prior art ejects liquid. [Figure 8] 1A and 1B are diagrams illustrating how the liquid ejection device according to the first embodiment ejects liquid. [Figure 9] 5(a) and 5(b) are diagrams showing waveforms of voltages applied to a piezoelectric element included in the liquid ejection device according to the first embodiment. [Figure 10] 6(a) and 6(b) are diagrams showing modified examples of the waveform of the voltage applied to the piezoelectric element included in the liquid ejection device according to the first embodiment. [Figure 11] 3 is a diagram showing an example of the arrangement relationship between nozzles and flow paths of a head according to the first embodiment. FIG. [Figure 12] 2A to 2C are diagrams illustrating an example of an ejection surface of a head according to the first embodiment and an application pattern of ejected liquid. [Figure 13]4A to 4C are diagrams illustrating a first modified example of the ejection surface of the head according to the first embodiment and the application pattern of the ejected liquid. [Figure 14] 5A and 5B are diagrams illustrating a second modified example of the ejection surface of the head according to the first embodiment and the application pattern of the ejected liquid. [Figure 15] 6A and 6B are diagrams illustrating a third modified example of the ejection surface of the head according to the first embodiment and the application pattern of the ejected liquid. [Figure 16] 13 is a diagram showing a fourth modified example of the ejection surface of the head according to the first embodiment and the application pattern of the ejected liquid. FIG. [Figure 17] 13 is a diagram showing a fifth modified example of the ejection surface of the head according to the first embodiment and the application pattern of the ejected liquid. FIG. [Figure 18] 13 is a diagram showing a sixth modified example of the ejection surface of the head according to the first embodiment and the application pattern of the ejected liquid. FIG. [Figure 19] 5A and 5B are diagrams showing a first modified example of the ejection surface of the head according to the first embodiment. [Figure 20] 6A and 6B are diagrams illustrating a second modified example of the ejection surface of the head according to the first embodiment. [Figure 21] FIG. 11 is a diagram showing an example of the overall configuration of a liquid ejection device according to a second embodiment. [Figure 22] FIG. 13 is a diagram showing an example of the overall configuration of a liquid ejection device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A liquid ejection device and a liquid ejection method according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the following embodiments are merely illustrative of the liquid ejection device and the liquid ejection method for embodying the technical idea of ​​the present embodiment, and are not limited to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, and relative positions of the components described in the embodiments are merely illustrative examples and are not intended to limit the scope of the present invention. The sizes, positional relationships, and the like of the components shown in each drawing may be exaggerated to clarify the explanation. Furthermore, in the following explanation, the same names and symbols indicate the same or similar components, and detailed explanations will be omitted as appropriate.

[0009] (First embodiment) <Example of Overall Configuration of Liquid Ejection Apparatus 100> Fig. 1 is a diagram showing an example of the overall configuration of a liquid ejection device 100 according to a first embodiment. In Fig. 1, the liquid ejection device 100 has a liquid ejection unit 10 that ejects liquid onto a target object 200, and a control unit 20 that controls the liquid ejection unit 10. The liquid ejection device 100 has four liquid ejection units 10 (10-1, 10-2, 10-3, 10-4), each of which is disposed around the target object 200 that is located at a coating position. Each of the liquid ejection units 10 has a head 11 corresponding to a liquid ejection head, a detection unit 12, and a robot arm 13.

[0010] The object 200 may be, for example, the body of a vehicle, an aircraft, a ship, etc. Vehicles include cars, trucks, trains, etc. In the example shown herein, the object 200 is a vehicle.

[0011] The head 11 (11-1, 11-2, 11-3, 11-4) includes a nozzle surface on which a plurality of nozzles for ejecting liquid are formed, and is attached to the tip of a robot arm 13. The robot arm 13 moves the head 11 relative to the object 200. In the example shown in FIG. 1, the robot arm 13 moves the head 11 relative to the object 200 by scanning the head 11 along the surface of the object 200. The head 11 is scanned by the robot arm 13 and can apply liquid ejected from the nozzles to the object 200.

[0012] The detection unit 12 (12-1, 12-2, 12-3, 12-4) is attached to the tip of the robot arm 13. The detection unit 12 outputs feature point information related to three-dimensional positions of three or more feature points on the object 200. The detection unit 12 may include a 3D camera such as a stereo camera, or a 3D sensor or a laser displacement meter other than a stereo camera. In the example shown in FIG. 1, the detection unit 12 includes a stereo camera, which measures the position and inclination in the XY directions, detects the painting start position, and detects the size of the object to be painted. The stereo camera has multiple cameras, and can acquire a distance image of the object 200 by a triangulation method based on the parallax between the images captured by each of the multiple cameras. The stereo camera can also output the distance image to the control unit 20 as feature point information. The detection unit 12 may include a laser displacement meter, which may measure the Z direction, detect the roof height of the object 200, and detect the curvature of the object 200, etc.

[0013] The robot arm 13 (13-1, 13-2, 13-3, 13-4) has links and joints. The robot arm 13 can change the relative position and relative inclination between the head 11 and the target 200 by rotating or displacing the links and joints, and can make the nozzle surface of the head 11 face the target 200.

[0014] The control unit 20 drives the robot arm 13 holding the four heads 11 based on predetermined shape data of the target object 200 and feature point information relating to the three-dimensional positions of three or more feature points output from each of the four detection units 12. The liquid ejection device 100 can paint the target object 200 by applying liquid ejected from the four heads 11 to the target object 200.

[0015] 1, the liquid ejection device 100 may have a supply unit and a maintenance unit. The supply unit can supply liquid to be ejected onto the target object 200 to each of the four heads 11. The maintenance unit removes thickened liquid and foreign matter adhering to the nozzle surface of the head 11, or thickened liquid and foreign matter present inside the head 11. This reduces ejection abnormalities such as non-ejection, deflected ejection, and ejection speed fluctuation in the head 11, and can maintain the ejection state of the head 11 in a normal state.

[0016] In the liquid ejection device 100, the object 200 is transported to a coating position, and the robot arm 13 moves the head 11 relative to the stopped object 200 to coat it. The object 200 that has been completely painted is transported out of the coating position, and the next object 200 is transported to the coating position.

[0017] <Example of the configuration of the head 11 included in the liquid ejection device 100> An example of the configuration of the head 11 included in the liquid ejection device 100 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a diagram showing an example of the configuration of the head 11 according to the first embodiment. Fig. 3 is a cross-sectional view of the head 11 according to the first embodiment, cut along plane S1 in Fig. 2. In Figs. 2 and 3, the head 11 has a supply port 111, a recovery port 112, and an ejection module 340.

[0018] The supply port 111 supplies pressurized liquid from the outside to the discharge module 340. The recovery port 112 discharges liquid that has not been discharged to the outside when a valve of a nozzle 311, which will be described later, is opened.

[0019] The ejection module 340 includes a housing 110 , a nozzle plate 321 having a nozzle 311 , a liquid flow path 322 , a valve 310 , and a piezoelectric element 324 .

[0020] Nozzle plate 321 is joined to housing 110, and ejects liquid supplied from supply port 111 from nozzle 311. Flow path 322 is a flow path common to multiple (eight in FIG. 2) ejection modules 340 provided in housing 110.

[0021] The valve 310 is an example of a needle-shaped valve body. The valve 310 is driven by a piezoelectric element 324 and reciprocates in the liquid ejection direction within the housing 110 to open and close the nozzle 311. The head 11 in this embodiment supplies pressurized liquid from the supply port 111 through the flow path 322 with the valve of the recovery port 112 closed. When the valve 310 is in a position to close the nozzle 311, the nozzle 311 does not eject liquid. On the other hand, when the piezoelectric element 324 is driven to raise the valve 310, the valve of the nozzle 311 is opened and liquid is ejected from the nozzle 311.

[0022] <Example of configuration of the supply unit 14 included in the liquid ejection device 100> Fig. 4 is a diagram showing an example of the configuration of the supply unit 14 included in the liquid ejection device 100. In Fig. 4, the supply unit 14 includes liquid tanks 330 (330-1, 330-2, 330-3, 330-4) as sealed containers that contain the liquid 325 to be ejected from the head 11. The liquid tanks 330 and the injection ports (supply ports 111) of the head 11 are connected via tubes 333 so that the liquid can flow therethrough.

[0023] The liquid tank 330 is connected to the compressor 230 via a pipe 331 including an air regulator 332, and the compressor 230 supplies pressurized air. As a result, pressurized liquid 325 is supplied to the inlet of the head 11, and the liquid ejection device 100 ejects the liquid 325 from the nozzle of the head 11.

[0024] It should be noted that the liquid tank 330 does not need to be provided for each head 11, and liquid may be supplied to all heads 11 from a single liquid tank 330.

[0025] <One example of scanning of the head 11 of the liquid ejection device 100> Fig. 5 is a diagram showing an example of a scan of the head 11 provided in the liquid ejection device 100. In Fig. 5, the object 200 is an automobile as an example, and the coating area 211 (211-1, 211-2, 211-3, 211-4) is the roof of the automobile. The coating area 211 is an area where each of the four robot arms 13 shown in Fig. 1 scans the head 11 over the object 200 to coat it. The coating area 211 and the scanning path T1 (T1-1, T1-2, T1-3, T1-4) are different for each of the four heads 11.

[0026] A coating range 211-1 indicates a range where coating is performed by causing the robot arm 13-1 to cause the head 11-1 to scan the object 200. A scanning path T1-1 indicates a path along which the head 11-1 scans the object 200.

[0027] A coating range 211-2 indicates a range where coating is performed by causing the robot arm 13-2 to cause the head 11-2 to scan the object 200. A scanning path T1-2 indicates a path along which the head 11-2 scans the object 200.

[0028] A coating range 211-3 indicates a range where coating is performed by causing the head 11-3 to scan the object 200 by the robot arm 13-3. A relative movement path T1-3 indicates a path along which the head 11-3 scans the object 200.

[0029] A coating range 211-4 indicates a range where coating is performed by causing the robot arm 13-4 to cause the head 11-4 to scan the object 200. A relative movement path T1-4 indicates a path along which the head 11-4 scans the object 200.

[0030] <Example of the Hardware Configuration of the Liquid Discharger 100> FIG. 6(A) is a block diagram showing an example of a coating system 10000, which will be described as a functional configuration of the liquid ejection device 100. FIG. 6(B) is a block diagram showing a software configuration of the controller 901 shown in FIG. 6(A). In FIG. 6(A), the coating system 10000 includes a controller 901, a head control device 902, a robot control device 904, coating robots 1000A and 1000B, and a PC (Personal Computer) 903. In FIG. 6(B), the controller 901 includes a CPU (Central Processing Unit) 9001, a ROM (Read Only Memory) 9002, a RAM (Random Access Memory) 9003, and an I / F (Interface) 9004. The controller 901, the head control device 902, and the robot control device 904 in FIG. 6(A) and FIG. 6(B) correspond to the control unit 20 in FIG. 1. Also, the head unit 103 in FIG. 6(A) corresponds to the liquid ejection device 100 in FIG. 1. In the following description, the two painting robots 1000A and 1000B will be collectively referred to as "painting robot 1000." The PC 903 is equipped with a RIP (Raster Image Processor) unit 9031 that performs image processing according to a color profile and user settings, and a rendering unit 9032 that breaks down data of the painted area to be applied to the object 200 (e.g., the body of an automobile) into painting (image) data for each scan (e.g., each movement of the head 11 in the main scanning direction).

[0031] The PC 903 is also connected to an input device 9033 for setting image data and coordinate data of the area to be painted on the target object 200, selecting a painting mode, setting the painting range (painting start position, painting end position), and issuing painting instructions. The input device 9033 is composed of a keyboard, mouse, touch panel, etc., and accepts input from a user. The PC 903 also acquires position data from the position measuring device 400 provided in the painting robot 1000, and generates a painting route for the painting robot 1000, etc.

[0032] The controller 901 is connected to a PC 903. The CPU 9001 is a calculation device that reads out a program or data stored in a ROM 9002 or the like onto a RAM 9003 and executes processing to realize each function of the painting robot 1000. The CPU 9001 functions as a system control unit 9011 that controls the overall operation of the painting system 10000 using image data and commands of the painting unit received from the PC 903. The PCU 9001 also functions as a memory control unit 9013 that controls a data storage unit 9012, a discharge period signal generating unit 9014 that generates a liquid discharge period signal, and a synchronization control unit 9015 that coordinates the movements of the painting robots 1000A and 1000B with the ink discharge operation. The CPU 9001 that functions as the memory control unit 9013 executes a program that is recorded in advance as stored data to realize the function of the controller 901.

[0033] The ROM 9002 is a non-volatile memory that can retain programs or data even when the power is turned off. The RAM 9003 is a volatile memory used as a work area for the CPU 9001, etc. The ROM 9002 and the RAM 9003 function as a data storage unit 9012 that stores image data, painting range (size of painting target) data, etc. received from the PC 903. A hard disk drive (HDD) or a solid state drive (SSD) may be used as a configuration that functions as the data storage unit 9012.

[0034] The I / F 9004 is an interface for inputting and outputting characters, numerical values, various instructions, etc., between various external devices, etc. The I / F 9004 is an interface that allows communication between the controller 901 and external devices such as the PC 903.

[0035] The painting robot 1000 is, for example, an articulated robot as described in Fig. 1. The painting robot 1000 has encoder sensors 109 at the first joint 104, the second joint 105, the third joint 106, and the like.

[0036] The encoder sensor 109 optically detects each slit of an encoder provided in, for example, the first joint 104, the second joint 105, and the third joint 106. Then, the positions of the first arm 101, the second arm 102, and the head unit 103 are detected from the amount of rotation of these arms, and three-dimensional position information of the head unit 103 is obtained. The ejection period signal generating unit 9014 generates an ejection period signal of the liquid from the output signal of the encoder sensor 109 and information indicating the resolution of the image data received from the PC 903.

[0037] The synchronization control unit 9015 coordinates the movements of the painting robots 1000A and 1000B with the ink ejection operations based on the image data and painting instructions received from the PC 903.

[0038] The head control device 902 receives a discharge periodic signal from a discharge periodic signal generating unit 9014 of the controller 901, and controls the ink discharge operation of the head 11 based on the discharge periodic signal. The robot control device 904 receives a synchronization control signal from a synchronization control unit 9015 of the controller 901, and controls the driving of the robot driving unit 72 based on the synchronization control signal. By controlling the driving of this robot driving unit 72, the first arm 101, the second arm 102, and the head unit 103 of the painting robot 1000 move to desired positions.

[0039] The painting robot 1000 includes a head unit 103, an encoder sensor 109, and a robot driving unit 72. The head unit 103 further includes a head 11 and a detection unit 12. Of these, the head 11 ejects liquid in response to a drive signal from a head control device 902. The detection unit 12 transmits the detection result of the target object 200 to a PC 903.

[0040] The robot driving unit 72 moves the first arm 101, the second arm 102, the head unit 103, etc. of the painting robot 1000 to desired positions in response to a driving signal from the robot control device 904. Note that, although the head control device 902 and the robot control device 904 in this example are common to the painting robot 1000A and the painting robot 1000B, the head control device 902 and the robot control device 904 may be provided in each painting robot 1000. Also, the RIP unit 9031 and the rendering unit 9032 may be provided in the system control unit 9011 of the controller 901 instead of in the PC 903.

[0041] <Comparison of the liquid ejection device of the present embodiment with the conventional technology> Here, a liquid ejection device in the prior art and the liquid ejection device 100 of this embodiment will be compared and described with reference to Figs. 7 and 8. Fig. 7 is a diagram showing how the liquid ejection device in the prior art ejects liquid. Fig. 7(a) shows how the liquid ejection device ejects liquid intermittently, and Fig. 7(b) shows the shape of the surface to be coated when the liquid is intermittently applied. Fig. 7(c) shows how the liquid ejection device ejects liquid continuously, and Fig. 7(d) shows the shape of the surface to be coated when the liquid is continuously applied. Fig. 8 is a diagram showing how the liquid ejection device 100 in this embodiment ejects liquid. Fig. 8(a) shows how the liquid ejection device ejects liquid intermittently, and Fig. 8(b) shows the shape of the surface to be coated when the liquid is applied by the configuration of this embodiment.

[0042] Incidentally, "discharging liquid intermittently" refers to periodically repeating a state in which liquid is discharged and a state in which liquid is not discharged while the head is moving in the main scanning direction (X-axis direction). A specific example of intermittently discharging liquid is discharging droplets. Meanwhile, "discharging liquid continuously" refers to continuing to discharge liquid while the head is moving in the main scanning direction. In other words, "discharging liquid continuously" refers to discharging liquid without interruption (or in a continuous manner) in the main scanning direction of the head while the head is moving in the main scanning direction. In the following explanation, intermittently discharged liquid may be referred to as "droplets" and continuously discharged liquid may be referred to as "liquid threads."

[0043] As shown in Figures 7(a) and 7(b), when a liquid ejection device ejects droplets, the droplets that land on the object to be coated spread out in a circular shape on the object to be coated, forming dots. The formed dots overlap with surrounding dots to fill in the gaps between them and form the coated surface. At this time, since the formed dots are circular, the edges of the coated surface have a wavy shape that follows the shape of the dots. Therefore, there is room for improvement in liquid ejection devices that eject droplets to form a coated surface, in that they cannot form smooth edges of the coated surface along the scanning direction.

[0044] Also, as shown in Figures 7(c) and 7(d), when the liquid discharge device discharges liquid threads, the liquid threads that land on the object to be coated do not form dots, but form lines along the main scanning direction (X-axis direction) of the liquid discharge device. Therefore, the shape of the edge in the sub-scanning direction (Y-axis direction) of the surface to be coated is characterized by being smoother along the main scanning direction (X-axis direction). However, compared with dots, the formed lines are less likely to spread in the direction perpendicular to the main scanning direction (Y-axis direction: also called the sub-scanning direction). Therefore, adjacent lines in the sub-scanning direction may not form a coating, and streaks may occur along the main scanning direction, leaving room for improvement.

[0045] In contrast, the liquid ejection device 100 according to this embodiment can eject droplets and liquid threads in parallel while the head moves in the main scanning direction (also referred to as one scan) as shown in Figures 8(a) and 8(b). Also, the edges of the surface to be coated in the main scanning direction can be formed by the liquid threads. Here, the head ejects droplets and liquid threads so that the lines of the liquid threads overlap the wavy edge shapes that follow the dot shapes. In this way, the liquid ejection device 100 can form a surface to be coated with smooth edges along the scanning direction while suppressing the occurrence of streaks in the coated area in one scan.

[0046] <How to eject droplets and strings> Next, a method for ejecting droplets and liquid filaments ejected by the liquid ejection device 100 according to this embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing the waveform of a voltage applied to the piezoelectric element 324. Fig. 9(a) shows the waveform when the liquid ejection device 100 ejects liquid intermittently (also called droplets), and Fig. 9(b) shows the waveform when the liquid ejection device 100 ejects liquid continuously (also called liquid filaments).

[0047] As shown in Fig. 9(a), when ejecting droplets, for example, a square wave voltage is applied to the valve of the nozzle 311 to alternate between an open state and a closed state. On the other hand, as shown in Fig. 9(b), when ejecting a filament, for example, a constant voltage is applied to the valve of the nozzle 311 to continuously open the valve without alternating between an open state and a closed state. In this way, by controlling the opening and closing of the valve of the nozzle 311 by the voltage applied to the piezoelectric element 324, it is possible to switch between ejecting droplets and ejecting a filament.

[0048] In this case, if the maximum value of the voltage applied for droplet ejection and liquid filament ejection is the same, the droplet ejection nozzle with the valve closed will eject less liquid per unit time. This may result in unevenness in the amount of liquid applied between the area coated with droplets and the area coated with liquid filaments. Therefore, in order to achieve uniform application regardless of the liquid ejection method, it is preferable to adjust the applied voltage for droplet ejection and liquid filament ejection so that the amount of liquid ejected per unit time is equal.

[0049] Here, an example of voltage application for adjusting the amount of liquid discharged per unit time will be described with reference to FIG. 10. FIG. 10 is a diagram showing the waveform of the voltage applied to the piezoelectric element 324 that adjusts the discharge amount of droplets and liquid filaments per unit time. FIG. 10(a) shows the waveform when the liquid discharge device 100 discharges liquid intermittently, and FIG. 10(b) shows the waveform when the liquid discharge device 100 discharges liquid continuously. Note that the nozzle for discharging droplets and the nozzle for discharging liquid filaments described below are assumed to have exactly the same structure such as the diameter of the hole and the flow path. However, the nozzle for discharging droplets and the nozzle for discharging liquid filaments may have different structures such as the diameter of the hole and the flow path. Even when the diameter of the hole and the structure of the flow path are different, the discharge amount of droplets and liquid filaments per unit time can be adjusted by adjusting the applied voltage.

[0050] As shown in FIG. 10(a), the voltage applied for ejecting droplets is greater than the voltage applied for ejecting a liquid filament (dashed line). This allows the amount of droplets ejected per unit time to be increased when the valve of the nozzle 311 is open. Also, as shown in FIG. 10(b), the voltage applied for ejecting a liquid filament is less than the voltage applied for ejecting droplets (dashed line). This allows the amount of liquid ejected per unit time to be reduced. In this way, by increasing the amount of liquid ejected as droplets and decreasing the amount of liquid ejected as a liquid filament, the amount of droplets and liquid filaments ejected per unit time can be made uniform. By making the amount of droplets and liquid filaments ejected per unit time uniform, uniform application of liquid can be achieved.

[0051] The applied voltage may be adjusted using a reference voltage (for example, a voltage that enables ejection of a predetermined amount of liquid, corresponding to a standard value calculated from the coating thickness and the concealment property of the base) determined for each nozzle 311. When the applied voltage is adjusted using the reference voltage, the voltage applied for ejecting droplets is set to be higher than the reference voltage, and the voltage applied for ejecting a filament of liquid is set to be lower than the reference voltage. However, when the applied voltage is adjusted using the reference voltage, adjustment may be made to either the voltage applied for ejecting droplets or the voltage applied for ejecting a filament of liquid.

[0052] <Relationship between flow path and nozzle> Next, the arrangement of the nozzles 311 and the flow paths 322 of the head 11 according to this embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram showing an example of the arrangement of the nozzles 311 and the flow paths 322 as viewed from the ejection surface of the head 11. In Fig. 3, the head 11 has eight nozzles 311 arranged in series. In Fig. 11, for the sake of simplicity, the head 11 will be described as having two nozzles 311 and three nozzles 311 arranged in parallel.

[0053] The head 11 has nozzles 311 arranged in a staggered pattern and flow paths 322 for supplying liquid to each nozzle 311. The flow paths 322 are formed so that the liquid supplied from the supply port 111 branches off and flows to the left and right nozzles. The flow paths 322 are also formed so that the liquid not ejected from the left and right nozzles 311 joins together downstream and flows to the recovery port 112.

[0054] <Liquid application example> Next, an example of liquid application by the head 11 according to this embodiment will be described with reference to Figs. 12 to 18. Fig. 12 is a diagram showing an example of the discharge surface of the head 11 and the application pattern of the liquid discharged from the head 11. In Figs. 12 to 18, the head 11 will be described as having two nozzles 311 and three nozzles 311 arranged in parallel as shown in Fig. 11. The arrows shown in Figs. 12 to 18 indicate the direction in which the head 11 is moved in the main scanning direction as an example of relatively moving the head 11 or the object 200, but also include the case in which the object 200 is moved in the X direction as the head 11 moves relatively in the arrow direction. The upper (lower) direction described later indicates the +Y (-Y) direction shown in each drawing, and the left (right) direction indicates the +X (-X) direction shown in each drawing. The clockwise (counterclockwise) rotation indicates a clockwise (counterclockwise) rotation around the Z axis as viewed from the +Z direction. These directions do not limit the scanning direction of the head 11, the arrangement of the nozzles 311, and the like, and may be reversed or rotated from the directions described below.

[0055] In FIG. 12, it is assumed that the head 11 applies a liquid thread to the edge of the application area of ​​the target object 200 in the sub-scanning direction at one side (lower side) in the vertical direction, which is a sub-scanning direction intersecting with the main scanning direction. The head 11 ejects a liquid thread from the nozzle 311L and ejects liquid droplets from the other nozzles 311 while moving in the main scanning direction. At this time, the nozzle 311L is located at the very end (lower end) in the vertical direction among the nozzles ejecting liquid. In other words, the nozzle 311L is arranged at the end side in the sub-scanning direction of the head 11 among the nozzles ejecting liquid in the direction intersecting with the direction of the relative movement of the head 11. In addition, the adjacent nozzles of the nozzles 311 and 311L are arranged so that the center-to-center distances (L1, L2, L3, L4) in the longitudinal direction of the head 11 are equal.

[0056] The droplets 510 discharged from the nozzle 311 land on the target object 200 and spread so that adjacent droplets 510 overlap each other on the surface of the target object 200. At this time, the lower end of the area coated by the nozzle 311 becomes wavy as the droplets 510 adjacent to each other spread so as to overlap each other in the main scanning direction. However, the nozzle 311L applies the liquid thread 501 so as to overlap the wavy area of ​​the droplets, so that the lower end (the edge of the coated area) can be shaped along the main scanning direction of the head 11. Note that, in this embodiment, the case where the head 11 is scanned linearly is given as an example, but at least a part of the scanning may include a curved line. Also, as shown in FIG. 13, the droplets 510 and the liquid thread 511 may be discharged while the head is tilted and moved in the main scanning direction. In this case, the distance between adjacent droplets 510 in the direction perpendicular to the main scanning direction, and the distance between the droplets 510 and the liquid thread 511 become narrower, so that the liquid can be applied more densely.

[0057] 14, it is assumed that the head 11 applies liquid to the edge of the area to be coated on the object 200 at both ends in the vertical direction (also called the sub-scanning direction) that intersects with the main scanning direction. While moving in the scanning direction, the head 11 ejects liquid threads 501 or 502 from the nozzles 311L located at both ends in the vertical direction, and ejects liquid droplets 510 from the other nozzles 311. Each of the nozzles 311L located at both ends in the vertical direction ejects liquid threads 501 or 502 so as to overlap with wavy areas formed at the top and bottom ends of the area applied by the nozzles 311. This allows both ends in the vertical direction (edges of the area to be coated) to be shaped along the main scanning direction of the head 11.

[0058] In FIG. 15, it is assumed that the width in the sub-scanning direction of the coating area of ​​the object 200 is narrower than the width in the sub-scanning direction that the head 11 can coat in one scan. While moving in the main scanning direction, the head 11 discharges a liquid thread from the nozzle 311L located at the lower end in the vertical direction among the nozzles that discharge liquid, and discharges droplets from the other nozzles 311. At this time, the nozzle 311n located below the nozzle 311L in the vertical direction is set not to discharge droplets 510 and liquid thread 501. The nozzle 311L discharges the liquid thread 501 so that it overlaps with the wavy area formed at the lower end of the area coated by the nozzle 311. This allows both ends in the vertical direction (edges of the coating area) to be shaped along the main scanning direction of the head 11.

[0059] 16, even if the width of the area to be coated on the object 200 in the sub-scanning direction in the vertical direction intersecting the main scanning direction of the head 11 is narrower than the width in the sub-scanning direction that the head 11 can coat in one scan, both ends in the vertical direction may be nozzles 311L. This allows both ends in the vertical direction (edges of the area to be coated) to have a shape that follows the main scanning direction of the head 11, as in the second modified example described in FIG.

[0060] 17, it is assumed that the width in the sub-scanning direction of the area to be coated on the object 200 is wider in the up-down direction intersecting with the main scanning direction of the head 11 than the width in the sub-scanning direction that the head 11 can coat in one scan. As shown in FIG. 17, the head 11 ejects droplets 510 from all of the nozzles 311 while moving in the main scanning direction from left to right. When coating of one line in the main scanning direction is completed, the head 11 moves in parallel below the coated line while maintaining the same posture. At this time, the head 11 does not eject droplets or liquid threads.

[0061] Then, when the head 11 finishes moving downward, it moves from right to left. At this time, when the head 11 scans from right to left (this scanning direction is also called the main scanning direction), the control unit 20 sets the nozzle 311 that applies the edge (lower end) of the area to be coated as the nozzle 311L that ejects the liquid thread 501. At the same time, the control unit 20 sets the other nozzle as the nozzle 311 that ejects the liquid droplets 510. As a result, even if the width in the sub-scanning direction of the area to be coated on the target object 200 in the vertical direction is wider than the width that the head 11 can coat in one scan, it is possible to form the edge of the area to be coated into a shape that follows the main scanning direction while suppressing the occurrence of streaks in the area to be coated.

[0062] In FIG. 18, it is assumed that the head 11 ejects liquid threads toward two ends of the edge of the area to be coated that are in mutually intersecting directions.

[0063] 18, the head 11 ejects droplets 510 from all of the nozzles 311 while moving in the main scanning direction (X-axis direction) from left to right. When application of one line in the main scanning direction is completed, the head 11 rotates counterclockwise with the ejection surface facing the target object 200.

[0064] When the rotation of the head 11 is completed, the head 11 ejects the liquid while moving from top to bottom (in the Y-axis direction, which is also the main scanning direction in this example). At this time, when the control unit 20 moves the head 11 below the applied line, the control unit 20 sets the two nozzles on the left side of the head 11 (also referred to as the two nozzles in the X-axis direction) as nozzles 311 that eject droplets 510. At the same time, the control unit 20 sets the third nozzle in the X-axis direction as nozzle 311L that continuously ejects liquid threads 501, and sets the remaining nozzles 311 as non-ejecting nozzles. After completing the setting of the ejection type of liquid for each nozzle, the head 11 is moved from top to bottom to eject the liquid. When the head 11 moves to below the applied line, the movement of the head 11 is stopped, the ejection of the liquid is stopped, and the head 11 is rotated clockwise.

[0065] When the rotation of the head 11 is completed, the head 11 ejects the liquid while moving from right to left (in the X-axis direction). At this time, the control unit 20 sets the nozzle 311 that applies the edge (lower end) of the area to be coated as the nozzle 311L that ejects the liquid thread 501 when the head 11 scans from right to left. At the same time, the control unit 20 sets the other nozzle as the nozzle 311 that ejects the liquid droplet 510. As a result, even if the width of the area to be coated of the target object 200 in the vertical direction is wider than the width that the head 11 can coat in one scan, it is possible to form the two edge sides of the area to be coated into a shape that follows the scanning direction while suppressing the occurrence of streaks in the area to be coated.

[0066] According to the above-described embodiment, the inside of the area to be coated can be coated without gaps with droplets, while the edge of the area to be coated can be smoothly coated along the scanning direction with liquid threads. Therefore, for example, when the roof of an automobile shown in FIG. 5 is to be coated, the coating ranges 211-1, 211-2, 211-3, and 211-4 of each of the four heads 11 can be coated linearly along the dashed lines while coating the inside of the dashed lines (edges) without gaps. However, the area of ​​the dashed lines adjacent to the coating ranges of the other heads 11 may be set to be coated without gaps by ejecting droplets.

[0067] <Nozzle arrangement example> Here, modified examples of the arrangement of the nozzles 311 in the head 11 will be described with reference to Figures 19 and 20. Figure 19 is a diagram showing a first modified example of the ejection surface of the head 11. Figure 20 is a diagram showing a second modified example of the ejection surface of the head 11.

[0068] The first modified example shown in FIG. 19 configures a head unit 50 having a plurality of heads described in the first embodiment. In FIG. 19, there are two heads (11A, 11B) of the heads 11 described in FIG. 11 to FIG. 18. The heads 11A and 11B are arranged to be shifted by half the nozzle interval (also called half pitch) in the nozzle arrangement direction (the vertical direction (also called the sub-scanning direction) intersecting the main scanning direction). In this case, the nozzle interval is, for example, the center-to-center distance between adjacent nozzles in the arrangement direction. The head unit 50 shown in this modified example can move in the same manner as the first embodiment described above and apply liquid to the application area.

[0069] 19, flow paths are formed in head 11A and head 11B that branch off from liquid tank 330 and supply liquid to each head, but the liquid supply path is not limited to this. For example, a configuration in which liquid is supplied separately from liquid tank 330 to each head may be used.

[0070] The second modified example shown in Fig. 20 differs from the first embodiment in that the head unit 50 has nozzles 311 for discharging droplets and nozzles 311L for discharging liquid filaments, which are provided in different heads (11D, 11E). The head 11 described in the first embodiment has a configuration in which the nozzles 311 are switched between discharging droplets and discharging liquid filaments. In contrast, the head unit 50 described in this modified example is composed of head 11D equipped with nozzles 311 that discharge only droplets, and head 11E equipped with nozzles 311L that discharge only liquid filaments.

[0071] In order to paint the sub-scanning direction end smoothly along the main scanning direction in one scan as in the first embodiment, it is preferable to arrange heads 11D and 11E in the main scanning direction and arrange the nozzles in a vertical direction (also called the sub-scanning direction) that intersects with the main scanning direction. However, because the distance between adjacent nozzles in the sub-scanning direction is small, it is structurally difficult to arrange heads 11D and 11E so that the ejected droplets and liquid threads overlap.

[0072] Therefore, in this modified example, the head 11D and the head 11E are arranged to be aligned in the main scanning direction. Also, the nozzle 311L of the head 11E is aligned in the main scanning direction with the nozzle 311 on the right side of the head 11D. This results in a configuration in which the liquid thread discharged from the nozzle 311L of the head 11E overlaps with the liquid droplets discharged from the nozzle 311 at the end in the vertical direction of the head 11D. Therefore, as in the first embodiment, the edge of the coating area can be shaped along the scanning direction. Note that the head 11E does not discharge liquid from all the nozzles 311L, but only from the nozzles 311L located at the end of the coating area.

[0073] <Second embodiment> A liquid ejection device according to the second embodiment will be described with reference to Fig. 21. Fig. 21 is a diagram showing an example of the overall configuration of a liquid ejection device 150 according to the second embodiment. The liquid ejection device 150 differs from the first embodiment in that the head 11 is fixed and the target object 200 is moved to paint.

[0074] 21 holds an object 200 with a robot arm 13 and moves it to the vicinity of a fixed head 11. The robot arm 13 then moves the object 200 to a liquid ejection position of the head 11 for coating. The liquid ejection device 150 in this embodiment is preferably applied when the object 200 is light or small enough to be movable by the robot arm 13 or the like. Note that the liquid ejection method in this embodiment can be the same as that in the first embodiment.

[0075] <Third embodiment> A liquid ejection device according to the third embodiment will be described with reference to Fig. 22. Fig. 22 is a diagram showing an example of the overall configuration of a liquid ejection device 160 according to the third embodiment. The liquid ejection device 150 includes a head 11, a first guide section 800 that moves the head 11 in the main scanning direction (X-axis direction) of the head 11, a fixed guide section 810 that unitizes the head 11 and the first guide section, and a second guide section 820 that moves the head 11 in a vertical direction (Y-axis direction) that intersects with the scanning direction. The liquid ejection device 150 differs from the first embodiment in that the head 11 is provided on a member other than the robot arm 13.

[0076] As shown in Fig. 22, the head 11 of the liquid ejection device 150 is provided on a first guide section 800, and is provided so as to be movable in the left-right direction (scanning direction). The head 11 and the first guide section 800 are unitized by a fixed guide section 810, and are provided so as to be movable in the up-down direction along a second guide section 820. This allows the head 11 to scan in two-dimensional directions along the first guide section 800 and the second guide section 820, and the liquid can be applied to the target object 200. Note that the liquid ejection method in this embodiment can employ the same method as in the first embodiment.

[0077] (Supplementary embodiment) So far, a liquid ejection device and a liquid ejection method according to one embodiment of the present invention have been described, but the present invention is not limited to the above-described embodiment, and other modifications, such as additions, changes, or deletions, can be made within the scope of what a person skilled in the art can conceive, and any aspect is within the scope of the present invention as long as it achieves the functions and effects of the present invention.

[0078] (First aspect) A first aspect of the liquid ejection device has a liquid ejection head equipped with a plurality of nozzles that ejects liquid onto an object, and ejects the liquid by moving the object or the liquid ejection head relatively to the object, wherein the plurality of nozzles include a first nozzle that ejects the liquid in droplets, and a second nozzle that ejects the liquid continuously, and the second nozzle is arranged on the end side of the liquid ejection head among the plurality of nozzles that eject the liquid, in a direction intersecting the direction of relative movement of the object or the liquid ejection head.

[0079] (Second aspect) The liquid ejection device of the second aspect is characterized in that, in the first aspect, it has a plurality of the first nozzles, and the distance between adjacent first nozzles in a direction intersecting the direction of the relative movement is equal to the distance between the first nozzle and the second nozzle adjacent in the direction intersecting the direction of the relative movement.

[0080] (Third aspect) A third aspect of the liquid ejection device is the liquid ejection device of the first or second aspect, characterized in that the second nozzle is arranged along the direction of the relative movement with at least one of the first nozzles.

[0081] (Fourth aspect) The liquid ejection device as a fourth aspect is any one of the first to third aspects, characterized in that the first nozzle and the second nozzle have the same diameter.

[0082] (Fifth aspect) A fifth aspect of the liquid ejection device is characterized in that in the first to fourth aspects, the flow path that supplies the liquid ejected from the first nozzle and the second nozzle to the liquid ejection head includes a common flow path.

[0083] (Sixth aspect) A sixth aspect of the liquid ejection device is characterized in that, in the first to fifth aspects, the amount of liquid ejected from the second nozzle per unit time is equal to the amount of liquid ejected from the first nozzle per unit time.

[0084] (Seventh aspect) The seventh aspect of the liquid ejection device is characterized in that, in the first to sixth aspects, it has a plurality of liquid ejection heads, and in a direction intersecting the direction of the relative movement, the nozzle of one of the plurality of liquid ejection heads is positioned between two nozzles of the other liquid ejection heads that are adjacent to each other in the intersecting direction.

[0085] (Eighth aspect) The eighth aspect of the liquid ejection device is characterized in that, in the first to seventh aspects, it has a control unit that controls the opening and closing of the first nozzle and the second nozzle by a valve body, and the control unit switches at least one of the first nozzles located at the end of the multiple nozzles arranged in a direction intersecting the direction of the relative movement to the second nozzle.

[0086] (Ninth aspect) A ninth aspect of the liquid ejection device is characterized in that, in the eighteenth aspect, the control unit switches the first nozzles, which are located at both ends in a direction intersecting the direction of the relative movement, to the second nozzles.

[0087] (Tenth aspect) A tenth aspect of the liquid ejection device is a liquid ejection device according to the eighth or ninth aspect, which ejects liquid onto a predetermined region by relatively moving the target object or the liquid ejection head in a two-dimensional direction, and is characterized in that the control unit sets all of the plurality of nozzles as the first nozzles when the liquid ejection head ejects the liquid into a region that does not include an end of the predetermined region, and sets the nozzle located at the end of the predetermined region as the second nozzle when the liquid ejection head ejects the liquid into a region that includes the end of the predetermined region.

[0088] (Eleventh aspect) An eleventh aspect of the liquid ejection method is a liquid ejection method using a liquid ejection device, wherein the liquid ejection device ejects liquid onto an object using a liquid ejection head having a plurality of nozzles, and a control unit controls the ejection of the liquid from the liquid ejection head and the relative movement of the object or the liquid ejection head, wherein the plurality of nozzles include a first nozzle that ejects the liquid in droplets and a second nozzle that ejects the liquid continuously, and the second nozzle is positioned on the end side of the liquid ejection head among the plurality of nozzles that eject the liquid in a direction intersecting the direction of the relative movement. [Explanation of symbols]

[0089] 10, 10-1, 10-2, 10-3, 10-4 Liquid discharge part 11, 11-1, 11-2, 11-3, 11-4, 11A, 11B, 11D, 11E Head 12, 12-1, 12-2, 12-3, 12-4 Detector 13, 13-1, 13-2, 13-3, 13-4 Robot arm 20 Control section 50 Head Unit 100 Liquid dispensing device 111 Supply Port 112 Collection Port 200 Objects 310 Valve (an example of a valve body) 311, 311L, 311n nozzles 322 Channel 510 droplet 501, 502 Liquid thread [Prior art documents] [Patent documents]

[0090] [Patent Document 1] Special table 2020‐513315

Claims

1. A liquid ejection head having a plurality of nozzles for ejecting liquid onto a target object, A liquid ejection device that ejects the liquid by relatively moving the target object or the liquid ejection head, The plurality of nozzles include a first nozzle that ejects the liquid in the form of droplets; a second nozzle for continuously discharging the liquid; The second nozzle is disposed on an end side of the liquid ejection head among the plurality of nozzles that eject the liquid in a direction intersecting a direction of relative movement of the object or the liquid ejection head. A liquid ejection device comprising:

2. A plurality of the first nozzles are provided, The distance between the first nozzles adjacent to each other in a direction intersecting the direction of the relative movement is The distance between the first nozzle and the second nozzle adjacent to each other in a direction intersecting the direction of the relative movement is equal to the distance between the first nozzle and the second nozzle. The liquid ejection device according to claim 1 .

3. The second nozzle is disposed along a direction of the relative movement with at least one of the first nozzles. The liquid ejection device according to claim 1 .

4. The diameter of the first nozzle and the diameter of the second nozzle are equal. The liquid ejection device according to claim 1 .

5. A flow path for supplying the liquid to be ejected from the first nozzle and the second nozzle to the liquid ejection head includes a common flow path. The liquid ejection device according to claim 1 .

6. The amount of liquid ejected from the second nozzle per unit time is equal to the amount of liquid ejected from the first nozzle per unit time. The liquid ejection device according to claim 1 .

7. The liquid ejection head includes a plurality of the liquid ejection heads, In a direction intersecting the direction of the relative movement, the nozzle of one of the liquid ejection heads is located between two nozzles of the other liquid ejection heads that are adjacent to each other in the intersecting direction. The liquid ejection device according to claim 1 .

8. a control unit that controls opening and closing of the first nozzle and the second nozzle by a valve body, The control unit switches at least one of the first nozzles arranged at an end of the plurality of nozzles arranged in a direction intersecting the direction of the relative movement to the second nozzle.

8. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.

9. The control unit switches the first nozzles located at both ends in a direction intersecting the direction of the relative movement to the second nozzles.

9. The liquid ejection device according to claim 8.

10. The object or the liquid ejection head is moved relative to the object in a two-dimensional direction to eject liquid onto a predetermined area, The control unit is when the liquid ejection head ejects the liquid in an area not including an end of the predetermined area, all of the plurality of nozzles are set as the first nozzles; When the liquid ejection head ejects the liquid in an area including an end of the predetermined area, the nozzle located at the end of the predetermined area is set as the second nozzle.

9. The liquid ejection device according to claim 8.

11. A liquid ejection method using a liquid ejection device, the liquid ejection device comprising: A liquid ejection head equipped with multiple nozzles ejects liquid onto a target object. a control unit controls the ejection of the liquid from the liquid ejection head and the relative movement of the target object or the liquid ejection head; The plurality of nozzles include a first nozzle that ejects the liquid in the form of droplets; a second nozzle that continuously ejects the liquid; The second nozzle is disposed on an end side of the liquid ejection head among the plurality of nozzles that eject the liquid in a direction intersecting the direction of the relative movement. A liquid ejection method comprising:

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