Liquid Dispensing System

Abstract

To provide a liquid discharge system that prevents the penetration of a cleaning liquid into the head.SOLUTION: A liquid discharge system includes: a head including a nozzle from which a liquid is to be discharged, a liquid chamber in communication with the nozzle through a communication port, a nozzle face having the nozzle, and a valve configured to open or close the communication port; and a cleaner including a cleaning nozzle to supply a cleaning liquid to the nozzle face. The cleaning liquid is supplied to the nozzle face in a state where the valve has closed the communication port.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection system. [Background technology]

[0002] Patent Document 1 discloses an inkjet recording head cleaning device that is provided with droplet ejection means for ejecting cleaning droplets into nozzles that eject ink droplets from the inkjet recording head. Summary of the Invention [Problem to be solved by the invention]

[0003] In the prior art, there was a problem in that the cleaning liquid entered the liquid chamber from the nozzle, diluting the ink or paint inside and degrading the coating quality. [Means for solving the problem]

[0004] The present invention provides a head including a nozzle for ejecting liquid, a liquid chamber communicating with the nozzle via a communication port, a nozzle surface having the nozzle, and a valve body for opening and closing the communication port, and a cleaning device having a cleaning nozzle for supplying cleaning liquid to the nozzle surface, wherein the cleaning liquid is supplied to the nozzle surface with the valve body closing the communication port. and a sealing member that enables a sealing portion to be formed with respect to the nozzle surface. It is characterized by: [Effects of the Invention]

[0005] According to the present invention, it is possible to provide a liquid ejection system that can reduce the infiltration of cleaning liquid into the head. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is an overall schematic view of a liquid ejection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of a schematic configuration of the hardware of a painting robot. [Figure 3] FIG. 1 is a schematic explanatory diagram of the ejection principle of a piezo head. [Figure 4] FIG. 10 is an explanatory diagram showing the state of nozzle contamination of a piezo head. [Figure 5] FIG. 10 is an explanatory diagram showing how the piezo head is cleaned. [Figure 6] FIG. 2 is a schematic overall perspective view showing an example of a valve head. [Figure 7] FIG. 1 is a schematic diagram illustrating the discharge principle of a valve head. [Figure 8] FIG. 3 is an explanatory diagram of a single liquid ejection module that constitutes a valve head. [Figure 9] FIG. 2 is an explanatory diagram showing an example of the appearance of a cleaning station. [Figure 10] FIG. 2 is an explanatory diagram showing an example of the internal configuration of a cleaning station. [Figure 11] FIG. 4 is an explanatory diagram showing a schematic diagram of wiring for cleaning liquid and air. [Figure 12] FIG. 10 is an explanatory diagram showing an example of a cleaning process. [Figure 13] FIG. 10 is an explanatory diagram showing the state of the nozzle surface after cleaning. [Figure 14] FIG. 10 is an explanatory diagram showing an example of a configuration for removing residual cleaning liquid. [Figure 15] 4 is a flowchart showing a series of operations from painting to cleaning in this embodiment. [Figure 16] 10 is a flowchart showing an example of a cleaning operation. [Figure 17] 10 is a flowchart showing an example of a cleaning operation. [Figure 18] 10 is a flowchart showing an example of a paint changing operation. [Figure 19] FIG. 10 is an explanatory diagram showing a modified example of the cleaning liquid removal configuration. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0008] <Outline of the liquid ejection system> First, an outline of a liquid ejection system will be described with reference to Fig. 1. Fig. 1 is an overall schematic diagram of a liquid ejection system according to an embodiment of the present invention. The liquid ejection system illustrated here is a painting system for painting automobile bodies and the like.

[0009] 1, a painting system 3000 includes a painting robot 1000 and a cleaning station 2000, and the painting system 3000 is installed in a predetermined painting booth 1. The painting robot 1000 is, for example, an articulated robot, and includes a head unit 100 at the tip of the robot arm. The painting robot 1000 can freely move the head unit 100 relative to an object 5000 such as a car body, and can accurately position a head (described later) included in the head unit 100 at a position on the object 5000 where painting is to be performed.

[0010] For example, a painting robot 1000 includes a robot body 10, an articulated arm device 20, and a head unit 100. The robot body 10 is fixed to the floor of a painting booth 1 and supports the articulated arm device 20. The robot body 10 also includes a robot control unit 70 therein, which will be described later.

[0011] The articulated arm device 20 includes a first arm 21a, a second arm 21b, a third arm 21c, a fourth arm 21d, a first joint 22a, a second joint 22b, and a third joint 22c. One end of the first arm 21a is supported by the robot body 10 so as to be rotatable (swivelable) in the direction of the dotted arrow r1, and the other end is connected to one end of the second arm 21b via the first joint 22a. The second arm 21b has one end connected to the first arm 21a via the first joint 22a, and is therefore rotatable in the direction of the dotted arrow r2.

[0012] The other end of second arm 21b is connected to one end of third arm 21c via second joint 22b. One end of third arm 21c is connected to second arm 21b via second joint 22b, and therefore is rotatable in the direction of dotted arrow r3. The other end of third arm 21c is connected to one end of fourth arm 21d via third joint 22c. One end of fourth arm 21d is connected to third arm 21c via third joint 22c, and therefore is rotatable in the direction of dotted arrow r4. The head unit 100 is supported on the other end of fourth arm 21d.

[0013] The rotational movement of each of the arms 21a to 21d is performed by controlling the drive motors provided in each of the joints 22a to 22c by the robot control unit 70. This enables the head unit 100 to move in the vertical direction (up and down) and horizontal direction (left and right) relative to the target object 5000.

[0014] The head placed at the painting position ejects ink, which is an example of a liquid, toward the object 5000 to paint the object 5000. A cleaning station 2000 is installed within the area reachable by the robot arm of the painting robot 1000, and when ink ejection is complete or a predetermined time has elapsed, the painting robot 1000 moves the head unit 100 to the cleaning station 2000. The cleaning station 2000 is equipped with a cleaning device for cleaning the head, and performs a cleaning process on the head provided in the head unit 100.

[0015] <Hardware configuration> Next, the schematic configuration of the hardware of the painting robot according to the embodiment will be described with reference to Fig. 2. Note that components may be added or deleted from the hardware configuration shown in Fig. 2 as needed. Fig. 2 is a block diagram showing an example of the schematic configuration of the hardware of the painting robot 1000.

[0016] The painting robot 1000 has a robot control unit 70 inside the robot body 10. The robot control unit 70 may be provided outside the robot body 10, or may be provided as a device separate from the painting robot 1000.

[0017] The robot control unit 70 includes a CPU (Central Processing Unit) 701, a ROM (Read Only Memory) 702, a RAM (Random Access Memory) 703, and an I / F (Interface) 704.

[0018] The CPU 701 controls the entire painting robot 1000. The CPU 701 is a computing device that implements each function of the painting robot 1000 by reading programs or data stored in the ROM 702 or the storage unit 705, etc., onto the RAM 703 and executing the processing.

[0019] The ROM 702 is a non-volatile memory that can retain programs or data even when the power is turned off. The RAM 703 is a volatile memory used as a work area for the CPU 701. The I / F 704 is an interface for inputting and outputting characters, numbers, various instructions, etc. to and from various external devices. The I / F 704 controls the display of various information such as a cursor, menu, window, characters, or images on a display unit 706 such as an LCD (Liquid Crystal Display). The storage unit 705 stores various data such as programs.

[0020] The display unit 706 displays various types of information such as a cursor, menus, windows, characters, images, etc. The operation panel 707 is a type of input means for inputting characters, numerical values, various instructions, etc., selecting or executing various instructions, selecting a processing target, moving the cursor, etc.

[0021] Furthermore, the robot control unit 70 is connected to the head 300, a cleaning station driving unit 708, a joint driving motor 709, and the like. The head 300 performs a liquid ejection operation onto the target object 5000 based on a command from the CPU 701. When cleaning the nozzle surface 301 of the head 300, the cleaning station driving unit 708 performs movement of the head 300 relative to the sealing member 205 of the cleaning station 2000 based on a command from the CPU 701. The joint driving motor 709 drives each of the joints 22a to 22c of the articulated arm device 20 of the painting robot 1000 based on a command from the CPU 701, and performs a rotational operation of each of the arms 21a to 21d.

[0022] <Head cleaning issues> Here, the issues that arise when cleaning a piezo head will be explained using Figures 3 to 5. Figure 3 is an explanatory diagram outlining the ejection principle of a piezo head, Figure 4 is an explanatory diagram showing how nozzles of a piezo head become dirty, and Figure 5 is an explanatory diagram showing how a piezo head is cleaned.

[0023] 3, Fig. 3(a) shows a state in which liquid is not being ejected, and Fig. 3(b) shows a state in which liquid is being ejected. A piezo head is a head configured to push out the liquid in a liquid chamber 311 by vibrating a piezo element 312 when the liquid is filled in the liquid chamber 311, thereby ejecting the liquid from a nozzle 302. A piezo head is configured, for example, by incorporating a piezo mechanism 310 as shown in Fig. 3 into the housing 303 of the head 300 shown in Fig. 2.

[0024] The piezo mechanism 310 includes a piezo element 312, a liquid supply port 306, a liquid chamber 311, and a piezo element holding member 307. The piezo element holding member 307 has a space 307a that is hollow in cross section, and is provided with a liquid supply port 306 near the nozzle 302. The liquid supply port 306 supplies liquid supplied from the outside into the liquid chamber 311. The piezo element 312 is disposed in the space 307a provided in the piezo element holding member 307, and is held by the piezo element holding member 307 so as to be capable of vibrating.

[0025] In the above configuration, when no drive voltage is applied to the piezoelectric element 312, the liquid in the liquid chamber 311 is not ejected from the nozzle 302, as shown in Fig. 3(a). When a drive voltage is applied to the piezoelectric element 312, the piezoelectric element 312 vibrates, and the liquid in the liquid chamber 311 is ejected from the nozzle 302 as a droplet D, as shown in Fig. 3(b).

[0026] When liquid ejection from nozzle 302 is completed in this manner, as shown in Figure 4(a) or 4(b), thickened liquid La may remain on nozzle 302 and nozzle surface 301. Furthermore, mist generated when liquid is ejected from nozzle 302 may adhere to the periphery of nozzle 302 on nozzle surface 301 as shown in Figure 4(c), and may remain as solidified matter Lb.

[0027] The thickened liquid La and the solidified matter Lb act as resistance when the liquid is ejected from the nozzle 302, causing the liquid to be ejected in a deviated manner (the liquid cannot be ejected correctly to the target position). Furthermore, if the viscosity of the liquid La increases significantly, this may cause ejection failure (the liquid cannot be ejected from the nozzle 302). Therefore, in order to maintain ejection quality, it is necessary to remove the thickened liquid La and the solidified matter Lb.

[0028] To address this issue, conventionally, a cleaning nozzle 201 and an air nozzle 211 are provided at positions facing the nozzle surface 301, as shown in FIG. 5(a), and cleaning liquid from the cleaning nozzle 201 and cleaning air from the air nozzle 211 are sprayed onto the nozzle surface 301 to clean the nozzle surface 301 and the nozzle 302. FIG. 5(b) is a partially enlarged cross-sectional view taken along line AA in FIG. 5(a). Removing foreign matter, such as the viscous liquid La and the solidified matter Lb, from the nozzle surface 301 requires high pressure for both the cleaning liquid and the cleaning air. As a result, the cleaning liquid may seep into the liquid chamber 311, as shown by the dashed line in FIG. 5(b). If the cleaning liquid seeps into the liquid chamber 311, the liquid in the liquid chamber 311 is diluted, which can affect the quality of the target object 5000. Therefore, conventionally, the liquid diluted by the cleaning liquid must be drained from the liquid chamber 311 and discarded before the next liquid ejection operation begins.

[0029] <Valve head configuration> The configuration of the valve head used in the present invention will be described below with reference to Figures 6 to 8. First, the schematic configuration of the valve head will be described with reference to Figure 6. Figure 6 is a schematic overall perspective view showing an example of a valve head.

[0030] 6, head 300 is a valve head that employs an inkjet system. Head 300 mainly comprises nozzle surface 301, nozzles 302, and housing 303. Nozzle surface 301 is provided on one surface of housing 303 and comprises nozzles 302 for ejecting liquid. Nozzles 302 are minute openings that can be opened and closed by a valve mechanism described below, and when nozzles 302 are opened, liquid is ejected from nozzles 302. Housing 303 incorporates a valve mechanism and the like that opens and closes nozzles 302.

[0031] Note that the nozzle surface 301 including the nozzles 302 may be a separate member such as a nozzle plate, and the nozzle plate may be held by the housing 303. Also, the number and arrangement of the nozzles 302 are not limited to the configuration shown in the figure. The number of nozzles 302 may be more than 18, or may be one instead of multiple nozzles. Also, the nozzles 302 may be arranged in a single row instead of multiple rows.

[0032] Figure 7 is an explanatory diagram outlining the discharge principle of the valve head, with Figure 7(a) showing the nozzle closed, Figure 7(b) showing the nozzle open, and Figure 7(c) showing the nozzle surface during cleaning.

[0033] The housing 303 of the head 300 shown in Fig. 6 incorporates a valve mechanism 304 as shown in Fig. 7. The valve mechanism 304 is provided so that one valve mechanism 304 is provided for one nozzle 302.

[0034] The valve mechanism 304 includes a valve 305, a liquid supply port 306, and a valve holding member 307. The valve holding member 307 has a space 307a that is hollow in cross section, and includes a liquid supply port 306 near the nozzle 302. The liquid supply port 306 receives liquid that is supplied under pressure from the outside into the valve holding member 307, and supplies the liquid to the rear portion of the nozzle surface 301. The valve 305 is disposed in the space 307a provided in the valve holding member 307, and is held by the valve holding member 307 via a bearing 308 so as to be movable in the axial direction. Here, the valve 305 is an example of a "valve body."

[0035] In the above configuration, when the tip of valve 305 is in close contact with nozzle 302 as shown in FIG. 7(a), nozzle 302 (communication port 301a) is closed, and liquid supplied from liquid supply port 306 is not ejected from nozzle 302. When voltage is applied to valve 305, valve 305 moves in the direction of arrow A as shown in FIG. 7(b), and nozzle 302 opens. This connects liquid supply port 306 and nozzle 302 via communication port 301a, and liquid is ejected from nozzle 302 as droplets D. Valve 305 opens and closes nozzle 302 at high speed at a frequency of several kHz, making it possible to eject liquid drop by drop.

[0036] 7(c), the tip of valve 305 comes into close contact with nozzle 302, closing nozzle 302. In this state, cleaning liquid is sprayed from cleaning nozzle 201 (described below) toward nozzle surface 301 as shown by the dashed line, making it possible to clean nozzle surface 301 and nozzle 302 while preventing the cleaning liquid from entering valve holding member 307.

[0037] The configuration of the valve mechanism 304 will be further explained using Figure 8. Figure 8 is an explanatory diagram of the valve mechanism itself that constitutes the head 300. Figure 8(a) is an overall cross-sectional view of the valve mechanism, and Figure 8(b) is an enlarged view of part B in Figure 8(a).

[0038] The valve mechanism 304 includes a valve 305 that opens and closes the nozzle 302, and a piezoelectric element 332 that drives the valve 305. The nozzle plate 310 is joined to the housing 303. In addition, the liquid chamber 312 forms a liquid flow path common to the multiple valve mechanisms 304 provided in the housing 303.

[0039] An elastic member 331 is provided at the tip of valve 305, which ensures that nozzle 302 is closed when the tip of valve 305 is pressed against nozzle plate 310. A bearing 321 is provided between valve 305 and housing 303, and a seal member 315 such as an O-ring is provided between bearing 321 and valve 305.

[0040] A piezoelectric element 309 is housed within space 322 of housing 303. A central space 333a of holding member 333 holds piezoelectric element 309, and piezoelectric element 309 and valve 305 are coaxially connected via tip end 333b of holding member 333. That is, holding member 333 has central space 333a that houses piezoelectric element 309, tip end 333b is connected to valve 305, and rear end 333c is fixed by restriction member 314 attached to housing 303.

[0041] Here, when a voltage is applied by the voltage application means 200, the piezoelectric element 309 drives the valve 305 in a direction that opens the nozzle 302. Therefore, when no voltage is applied to the piezoelectric element 309, the valve 305 closes the nozzle 302, so that ink is not ejected from the nozzle 302 even if ink is supplied under pressure to the liquid chamber 312. When a voltage is applied to the piezoelectric element 309, the piezoelectric element 309 contracts and pulls the valve 305 via the holding member 333, causing the valve 305 to move away from the nozzle 302 and open the nozzle 302. As a result, the nozzle 302 and the liquid chamber 312 communicate with each other via the communication port 301a, and ink supplied under pressure to the liquid chamber 312 is ejected from the nozzle 302.

[0042] As described above, this embodiment includes a head 300 including a nozzle 302 that ejects liquid, a liquid chamber 312 that communicates with the nozzle 302 via a communication port 301a, a nozzle surface 301 that has the nozzle 302, and a valve 305 that opens and closes the communication port 301a, and a cleaning device (cleaning nozzle 201, tube 202, etc.) that has a cleaning nozzle 201 that supplies cleaning liquid to the nozzle surface 301, and the cleaning liquid is supplied to the nozzle surface 301 with the valve 305 closing the nozzle 302 (communication port 301a). This makes it possible to clean the nozzle surface 301 and the nozzle 302 while preventing the cleaning liquid from entering the head 300.

[0043] <Cleaning station configuration> The configuration of the cleaning station will be described with reference to FIGS.

[0044] <<Appearance configuration>> First, the external configuration of the cleaning station 2000 will be described with reference to Fig. 9. Fig. 9 is an explanatory diagram showing an example of the external appearance of the cleaning station.

[0045] The cleaning station 2000 is installed in the painting booth 1 as described above, and when the painting robot 1000 moves the head unit 100 to the cleaning station 2000, the cleaning station 2000 performs a cleaning (washing) process on the head 300. The cleaning station 2000 includes a main body housing 204, a sealing member 205, and a base plate 260.

[0046] Main body housing 204 has an opening 204a on a part of its side surface, the opening 204a having an area smaller than the area of ​​nozzle surface 301 of head 300. A sealing member 205 is provided around (on the edge of) opening 204a via a base plate 260. When a cleaning process is performed on head 300, nozzle surface 301 is pressed against sealing member 205, thereby forming a sealed space (hereinafter referred to as a sealed portion) between head 300 and cleaning station 2000 (the sealed portion will be described later).

[0047] The cleaning station 2000 is generally provided integrally with the system (or device) on which the head 300 is mounted, but in this embodiment, the painting robot 1000 and the cleaning station 2000 are structured independently. This prevents the cleaning liquid from spilling from the painting robot 1000 during transportation or installation, and also reduces the weight capacity of the painting robot 1000.

[0048] As described above, in this embodiment, the head 300 and the cleaning station 2000 (specifically, the cleaning nozzle 201, air nozzle 211, and tubes 202, 212, etc., described below) are installed in the painting booth 1 as independent devices. This makes it possible to prevent spillage of cleaning liquid when installing the painting robot 1000 and to reduce the weight capacity of the painting robot 1000. Furthermore, by separating the head 300 from the cleaning station 2000, the degree of freedom in the direction of the head during cleaning increases. Furthermore, the cleaning performance of the cleaning station 2000 for waste liquid treatment is improved.

[0049] <<Internal structure>> Next, the internal configuration of the cleaning station 2000 will be described using Figure 10. Figure 10 is an explanatory diagram showing an example of the internal configuration of the cleaning station, where Figure 10(a) is an explanatory diagram showing the positional relationship of each component when a sealed portion is formed, Figure 10(b) is an explanatory diagram showing the state in which cleaning liquid has been sprayed onto the nozzle surface, and Figure 10(c) is an explanatory diagram showing the state in which cleaning air has been blown onto the nozzle surface. Note that Figure 10 omits the base plate 260 shown in Figure 9, and provides a simplified explanation.

[0050] 10(a), cleaning station 2000 includes therein a cleaning nozzle 201, a tube 202 connected to cleaning nozzle 201, an air nozzle 211, a tube 212 connected to air nozzle 211, a nozzle holder 203 that holds cleaning nozzle 201 and air nozzle 211 at one end, and a main body housing 204 that holds the other end of nozzle holder 203. Here, cleaning nozzle 201, air nozzle 211, and tubes 202 and 212 are an example of a "cleaning device." Furthermore, cleaning nozzle 201 and tube 202 are also an example of a "first cleaning liquid removal means," and air nozzle 211 and tube 212 are also an example of a "second cleaning liquid removal means."

[0051] A sealing member 205 is provided around an opening 204a formed in a part of the main body housing 204. When a cleaning process is performed on the head 300, the nozzle surface 301 of the head 300 is pressed against the sealing member 205, thereby forming a sealed portion 206 between the head 300 and the cleaning station 2000. Note that at this time, the nozzle 302 of the head 300 is in the "closed state" shown in FIG. 7(a) and the like.

[0052] The nozzle surface 301 is fixed facing in a direction intersecting the horizontal plane (vertical in this embodiment). If the nozzle surface 301 is fixed facing downward in the direction of gravity, the cleaning liquid will be sprayed upward toward the nozzle surface 301, and the cleaning liquid must be sprayed against gravity, resulting in reduced cleaning efficiency. Furthermore, if the nozzle surface 301 is fixed at an angle greater than 90 degrees relative to the horizontal plane, the range over which the cleaning liquid bounces off the nozzle surface 301 will increase, resulting in an increase in the size of the anti-scattering member and the overall size of the device. Furthermore, cleaning liquid is likely to remain at the corners between the sealing member 205 and the nozzle surface 301, and it may not be possible to completely remove the cleaning liquid after cleaning. The angle of the nozzle surface 301 relative to the horizontal plane may be set appropriately, taking the above points into consideration, as long as the cleaning liquid does not spray upward.

[0053] The cleaning nozzle 201 and the air nozzle 211 are installed at positions (in this embodiment, positions above the normal line in the direction of gravity) that avoid the normal line (on the dashed line in FIG. 10(a)) drawn from the center of the nozzle provided on the nozzle surface 301 of the head 300. The liquid ejected onto the target object 5000 is not limited to a single color, and the type, such as color or characteristics, may be changed. In this case, it is necessary to discharge the liquid remaining in the nozzle of the head 300, etc., and replace the liquid. In this embodiment, the liquid replacement (changing) process is also performed within the cleaning station 2000, so no new equipment is required, making it possible to reduce the size and cost of the equipment.

[0054] If the cleaning nozzle 201 and the air nozzle 211 are on the normal line described above during this liquid replacement process, the liquid ejected during the liquid replacement process will splash onto the cleaning nozzle 201 and the air nozzle 211, soiling the cleaning nozzle 201 and the air nozzle 211. Therefore, in this embodiment, the cleaning nozzle 201 and the air nozzle 211 are installed at positions that avoid the normal line drawn from the center of the nozzle, thereby preventing the nozzles 201 and 211 from being soiled.

[0055] As described above, in this embodiment, the cleaning nozzle 201 is installed at a position different from the normal line drawn from the center of the nozzle 302 during cleaning.

[0056] As described above, the nozzle surface 301 is disposed so as to intersect with a horizontal plane, and the cleaning nozzle 201 is disposed above the perpendicular to the nozzle surface 301 in the direction of gravity.

[0057] As a result, the liquid discharged during the liquid replacement (changing) process or the like will not hit the cleaning nozzle 201, and the cleaning nozzle 201 can be prevented from being soiled.

[0058] Furthermore, as described above, when changing the type of liquid, the nozzle surface 301 is cleaned after the cleaning device has discharged the liquid remaining in the nozzles 302 before the change. This allows the liquid replacement (change) process to be performed with fewer cleaning operations.

[0059] As described above, the cleaning station 2000 is also provided with a sealing member 205 that allows the formation of a sealed portion 206 on the nozzle surface 301. This makes it possible to prevent the cleaning liquid from splashing around the cleaning station 2000.

[0060] When the head 300 is moved to the cleaning station 2000 by the painting robot 1000 and the sealed portion 206 is formed, the cleaning liquid Lc is sprayed from the cleaning nozzle 201 toward the nozzle surface 301, as shown in Fig. 10(b). The spraying of the cleaning liquid Lc from the cleaning nozzle 201 ends after a predetermined time has elapsed.

[0061] The shape of the cleaning nozzle 201 is not particularly limited, but in this embodiment, the cleaning liquid Lc sprayed from the cleaning nozzle 201 has a predetermined spray width. This spray width can be adjusted by selecting, for example, a full-cone-shaped nozzle as the cleaning nozzle 201, allowing a single nozzle to clean a wide area. Note that if a linear nozzle is selected as the cleaning nozzle 201, the cleaning liquid Lc can be applied to the nozzle surface 301 with pinpoint accuracy, thereby further enhancing cleaning power. Furthermore, if a fan-shaped nozzle is selected as the cleaning nozzle 201, it is possible to achieve both wide-area cleaning and cleaning power.

[0062] If the cleaning liquid Lc is left adhering to the nozzle surface 301, the cleaning liquid Lc will fall onto the target object 5000 when the liquid is ejected onto the target object 5000, leading to deterioration in the quality of the target object 5000. To prevent the cleaning liquid Lc from falling onto the target object 5000 during the liquid ejection operation, as shown in FIG. 10(c), after the cleaning liquid Lc is ejected, cleaning air Ac is ejected from the air nozzle 211 to remove the cleaning liquid Lc adhering to the nozzle surface 301. The ejection of cleaning air Ac from the air nozzle 211 also ends after a predetermined time has elapsed.

[0063] <<Cleaning fluid and air supply system>> Next, the supply system for cleaning liquid and air in the cleaning station 2000 will be described with reference to Fig. 11. Fig. 11 is an explanatory diagram that schematically shows the wiring for cleaning liquid and air.

[0064] Facility air 220, which is an air source for facilities, etc., supplies pressurized air to a primary regulator 221. The primary regulator 221 adjusts the air pressure and supplies the pressure-adjusted air to a primary joint 222. The primary joint 222 branches the air from the primary regulator 221 into two lines, and the primary joint 222 supplies one line to a secondary joint 223 and the other line to a solenoid valve 224.

[0065] The secondary joint 223 further branches the air from the primary joint 222 into two lines, and the secondary joint 223 supplies one line to a liquid pressure adjustment regulator 225 and the other line to an air pressure adjustment regulator 226. The liquid pressure adjustment regulator 225 adjusts the pressure of a pressurized tank 227 installed downstream, and pressurizes the cleaning liquid contained in the pressurized tank 227 to a predetermined pressure and supplies it to the cleaning nozzle 201.

[0066] On the other hand, the air supplied from the primary joint 222 to the solenoid valve 224 is supplied to a cleaning liquid ON / OFF valve 228 installed downstream of a pressurized tank 227 and an air ON / OFF valve 229 installed downstream of an air pressure adjustment regulator 226, and is used to control the on / off of the ON / OFF valves 228, 229. The solenoid valve 224 is connected to a control terminal 230 such as a PC (Personal Computer).

[0067] In the above configuration, when the head 300 moves to the cleaning station 2000 and the control terminal 230 determines that the gap between the nozzle surface 301 and the cleaning station 2000 has been sealed by the sealing member 205, the control terminal 230 turns on the input (supply) of air from the solenoid valve 224 to the cleaning liquid ON / OFF valve 228. This causes the cleaning liquid Lc to be sprayed from the cleaning nozzle 201 toward the nozzle surface 301. After a predetermined time has elapsed, the control terminal 230 turns off the input (supply) of air from the solenoid valve 224 to the cleaning liquid ON / OFF valve 228, ending the spraying of the cleaning liquid Lc.

[0068] The control terminal 230 determines whether the robot arm of the painting robot 1000 has reached the coordinates by teaching the coordinates indicating the position where the sealed portion 206 will be formed to the painting robot 1000 in advance. Alternatively, the control terminal 230 may detect the position of the robot arm using a position sensor without using the coordinate information.

[0069] However, if the ink, paint, or cleaning liquid is a liquid containing a solvent and the paint booth 1 is designated as an explosion-proof area, the use of electrical equipment may violate the explosion-proof standards, and the position sensor may not be usable. However, this embodiment is not limited to a configuration in which the determination is made based on coordinate information. For example, if the paint booth 1 is not designated as an explosion-proof area, the control terminal 230 may determine the formation state of the sealed portion 206 based on the detection results of a position sensor or the like.

[0070] Once the spraying of cleaning liquid Lc onto nozzle surface 301 has finished, control terminal 230 turns on the input (supply) of air from solenoid valve 224 to air ON / OFF valve 229. This causes cleaning air Ac to be sprayed from air nozzle 211 toward nozzle surface 301. After a predetermined time has elapsed, control terminal 230 turns off the input (supply) of air from solenoid valve 224 to air ON / OFF valve 229, ending the spraying of cleaning air Ac.

[0071] <Explanation of cleaning operation> Next, the cleaning operation of this embodiment will be described with reference to Figures 12 to 14. Figure 12 is an explanatory diagram showing an example of the cleaning process.

[0072] Cleaning of the nozzle surface 301 of the head 300 is performed in the order of Figures 12(a) to 12(e). After liquid discharging onto the object 5000 is completed, the painting robot 1000 moves the head 300 to the cleaning station 2000, and presses the nozzle surface 301 of the head 300 against the sealing member 205 of the cleaning station 2000. Then, as shown in Figure 12(a), the painting robot 1000 fixes (holds) the position of the head 300 at the position where the sealing portion 206 is formed. At this time, the nozzle 302 of the head 300 is in the "closed state" shown in Figure 7(a) etc.

[0073] 12(b), cleaning liquid Lc is sprayed from cleaning nozzle 201 toward nozzle surface 301 to wash away thickened liquid La and solidified matter Lb adhering to nozzle surface 301 and nozzle 302. Subsequently, as shown in FIG. 12(c), cleaning air Ac is sprayed from air nozzle 211 toward nozzle surface 301 to blow away cleaning liquid Lc and other matter remaining on nozzle surface 301 and nozzle 302.

[0074] 12(a) to 12(c) alone may not be enough to completely remove dirt from the nozzle surface 301. For example, as shown in Fig. 13, cleaning liquid Lc and the like that was not completely removed by cleaning air Ac may remain on the edge between the nozzle surface 301 and the sealing member 205.

[0075] Therefore, once spraying of the cleaning air Ac has been completed while the sealed portion 206 has been formed, the coating robot 1000 moves the head 300 in a direction that releases the pressure between the nozzle surface 301 and the sealing member 205. Then, as shown in FIG. 12(d), the nozzle surface 301 is moved a predetermined distance away from the sealing member 205. Next, as shown in FIG. 12(e), cleaning air Ac is sprayed again from the air nozzle 211 toward the nozzle surface 301 to blow away any cleaning liquid Lc remaining on the nozzle surface 301.

[0076] This makes it possible to remove cleaning liquid Lc and the like that remains on the edges of the nozzle surface 301 and the sealing member 205. In addition, because the re-spray is performed using the air nozzle 211 and existing parts are used, there is no need to replace consumables, which reduces costs and makes the device more compact.

[0077] 12(e), the cleaning air Ac is re-sprayed without forming the sealed portion 206, so the cleaning liquid Lc blown away by the cleaning air Ac scatters around. Therefore, it is desirable to provide a member 240 on the main body housing 204 of the cleaning station 2000, as shown in FIG.

[0078] As described above, this embodiment includes a cleaning nozzle 201 that removes cleaning liquid Lc supplied to the nozzle surface 301 when a sealing portion 206 is formed on the nozzle surface 301, and an air nozzle 211 that removes cleaning liquid Lc supplied to the nozzle surface 301 when a sealing portion 206 is not formed on the nozzle surface 301.

[0079] As described above, the air nozzle 211 uses cleaning air Ac that is blown toward the nozzle surface 301.

[0080] As a result, the cleaning air Ac reaches every corner of the nozzle surface 301, removing the cleaning liquid Lc and other residue remaining on the edge between the nozzle surface 301 and the sealing member 205. The above-described cleaning operation is performed after painting of one vehicle body is completed or after the vehicle body painting schedule for one day is completed. The timing of the cleaning operation is not particularly limited; for example, the cleaning operation may be performed before painting begins. FIG. 15 is a flowchart showing a series of operations from painting to cleaning in this embodiment. As shown in FIG. 15, the painting system 3000 paints the object 5000 (step S100). Once painting is completed, the painting system 3000 performs a cleaning operation (step S200). Next, once the cleaning operation is completed, the painting system 3000 determines whether any objects 5000 to be painted remain (step S300). If it is determined that no objects 5000 remain, the painting operation ends. If it is determined in step S300 that the object 5000 remains, the process returns to step S100, and painting of the object 5000 is started.

[0081] An example of the flow of the cleaning operation in this embodiment will now be described with reference to Figures 16 to 18. Figure 16 is a flow chart showing an example of the cleaning operation.

[0082] When the cleaning operation for the head 300 is started, the robot arm moves from the home position for the painting operation to the home position for the cleaning operation (Step S1). When the robot arm reaches the cleaning home position, the robot control unit 70 determines whether the valve 305 of the head 300 is closed (the nozzle 302 is closed) (Step S2). If it is determined in Step S2 that the valve 305 is not closed (No), the valve 305 is closed and the nozzle 302 is set to a closed state (Step S3).

[0083] Once the valve 305 is closed, the head 300 and the sealing member 205 are brought into contact with each other to form a sealed section 206 between the head 300 and the cleaning station 2000 (step S4). Once the sealed section 206 is formed, the cleaning nozzle 201 installed in the sealed section 206 ejects (sprays) a cleaning liquid to clean the nozzle surface 301 (step S5).

[0084] Next, air is sprayed onto the nozzle surface 301 to which the cleaning liquid has adhered from the air nozzle 211 installed in the sealing portion 206 (step S6). After that, the head 300 and the sealing member 205 are separated by a predetermined distance, and the sealing portion 206 is released (step S7).

[0085] After the sealing portion 206 is released in step S7, air is again sprayed onto the nozzle surface 301 by the air nozzle 211 (step S8). By performing this second air spray, it becomes possible to blow away, from the nozzle surface 301, any foreign matter such as dirt that was pushed into the contact area between the nozzle surface 301 and the sealing member 205 during the first air spray. Once the second air spray is complete, the robot arm moves to the home position, and the cleaning operation is completed (step S9).

[0086] Figure 17 is a flowchart showing another example of a cleaning operation. The flowchart shown in Figure 17 differs from the flowchart shown in Figure 16 in that a paint change operation has been added between step S1 and step S2. Therefore, the same processes or operations as those in the flow shown in Figure 16 are given the same reference numerals, and their explanations will be omitted.

[0087] In the flow shown in Fig. 17, after step S1, the robot control unit 70 determines whether to change the paint used for painting (step S10). If it is determined in step S10 that the paint will not be changed (No), the process proceeds to step S2, and thereafter, the same processing or operation as in the flow shown in Fig. 16 is executed. If it is determined in step S10 that the paint will be changed (Yes), the paint change operation is carried out (step S11).

[0088] The paint changing operation is performed, for example, based on the flow shown in FIG. 18. First, the robot control unit 70 causes the head 300 to eject the paint before the change (step S111). Next, it determines whether to clean the tube that supplies the paint to the head 300 (step S112). If it is determined in step S112 that the tube should not be cleaned (No), the new paint is supplied to the head 300, and the paint changing operation is completed (step S114). If it is determined in step S112 that the tube should be cleaned (Yes), the tube is cleaned (step S113), and then step S114 is performed. Once the paint changing operation is completed, the process proceeds to step S2, and thereafter, the same processing or operation as in the flow of FIG. 16 is performed.

[0089] <Modification> A modification of this embodiment will be described with reference to Fig. 19. Fig. 19 is an explanatory diagram showing a modification of the cleaning liquid removal configuration.

[0090] This modified example replaces the process shown in Fig. 12(e). In Fig. 12(e), cleaning air Ac is re-sprayed from the air nozzle 211 toward the nozzle surface 301 to blow away the cleaning liquid Lc remaining on the nozzle surface 301, but this modified example differs in that a liquid absorber 250 installed in the cleaning station 2000 or another position in the coating booth 1 is used.

[0091] That is, as shown in FIG. 12(d), the nozzle surface 301 is separated a predetermined distance from the sealing member 205, and then, as shown in FIG. 19, the head 300 is first rotated 90 degrees to orient the nozzle surface 301 vertically downward. Next, the nozzle surface 301 is pressed against the liquid absorber 250. As a result, the liquid absorber 250 absorbs the cleaning liquid Lc remaining on the nozzle surface 301 by capillary action of the liquid absorber 250. Note that the liquid absorber 250 is preferably configured to be replaceable, since its absorbency deteriorates if too much cleaning liquid Lc or the like accumulates. In this modified example, the cleaning liquid Lc or the like is removed by bringing the liquid absorber 250 into contact with the nozzle surface 301, resulting in an excellent removal effect and reducing the scattering of the cleaning liquid or the like to the surrounding area.

[0092] As described above, in this modification, the liquid absorber 250 capable of absorbing liquid is used instead of the air nozzle 211. As a result, the liquid absorber 250 is brought into contact with the nozzle surface 301 to remove the cleaning liquid Lc, etc., and therefore, scattering of the cleaning liquid, etc. to the surroundings can be reduced.

[0093] <Supplementary information> In the present invention, the liquid may be a solution, suspension, emulsion, or the like containing a solvent such as water or an organic solvent, a colorant such as a dye or a pigment, a polymerizable compound, a resin, a surfactant, or the like, a functionalizing material such as DNA, an amino acid, a protein, or calcium, an edible material such as a natural colorant, or the like. The liquid may also contain fine powders such as metal powder. These liquids can be used, for example, as inkjet inks, coating materials, surface treatment solutions, liquids for forming components of electronic devices or light-emitting devices, liquids for forming electronic circuit resist patterns, and liquid materials for 3D modeling.

[0094] The above description is merely an example, and the present invention provides unique effects for each of the following aspects.

[0095] The first aspect is characterized in that it comprises a head having a nozzle that ejects liquid, a liquid chamber that communicates with the nozzle via a communication port, a nozzle surface having the nozzle, and a valve body (e.g., valve 305) that opens and closes the communication port, and a cleaning device (e.g., cleaning nozzle 201, air nozzle 211, and tubes 202, 212) having a cleaning nozzle that supplies cleaning liquid to the nozzle surface, and the cleaning liquid is supplied to the nozzle surface with the valve body closing the communication port.

[0096] According to the first aspect, it is possible to provide a liquid ejection system that can reduce the infiltration of cleaning liquid into the head.

[0097] The second aspect is characterized in that, in the first aspect, the cleaning nozzle is installed at a position different from the normal line drawn from the center of the nozzle (for example, the dashed line shown in Figure 8(a)) during cleaning.

[0098] The third aspect is characterized in that, in the first or second aspect, the nozzle surface is installed so as to intersect with a horizontal plane, and the cleaning nozzle is installed above the perpendicular line of the nozzle surface in the direction of gravity.

[0099] According to the second and third aspects, the liquid does not hit the washing nozzle, and the washing nozzle can be prevented from being soiled or damaged.

[0100] A fourth aspect is characterized in that, in any of the first to third aspects, when the type of liquid is changed, cleaning of the nozzle surface is performed after the cleaning device has discharged the liquid remaining in the nozzle before the change.

[0101] According to the fourth aspect, the liquid change process can be performed with fewer cleanings.

[0102] A fifth aspect is characterized in that in any of the first to fourth aspects, a sealing member is provided that enables the formation of a sealed portion on the nozzle surface.

[0103] According to the fifth aspect, it is possible to prevent the cleaning liquid from scattering around the cleaning device.

[0104] The sixth aspect is characterized in that the fifth aspect is provided with a first cleaning liquid removal means (e.g., cleaning nozzle 201) that removes the cleaning liquid supplied to the nozzle surface when the sealed portion is formed on the nozzle surface, and a second cleaning liquid removal means (e.g., air nozzle 211) that removes the cleaning liquid supplied to the nozzle surface when the sealed portion is not formed on the nozzle surface.

[0105] The seventh aspect is the sixth aspect, characterized in that the second cleaning liquid removal means (for example, air nozzle 211) uses air (for example, cleaning air Ac) that is blown toward the nozzle surface.

[0106] According to the sixth and seventh aspects, it is possible to reduce the amount of cleaning liquid left behind on the nozzle surface.

[0107] An eighth aspect is the sixth aspect, characterized in that the second cleaning liquid removal means is an absorbent (for example, a liquid absorbent 250) capable of absorbing the liquid.

[0108] According to the eighth aspect, the cleaning liquid and the like are removed by bringing the absorbent into contact with the nozzle surface, so that scattering of the cleaning liquid and the like into the surroundings can be reduced. [Explanation of symbols]

[0109] 3000 Painting System 1000 Painting Robots 100 head unit 300 head 301 Nozzle surface 302 Nozzle 305 Valve 2000 Cleaning Station 201 Cleaning nozzle 211 Air nozzle 205 Sealing member 206 Sealed part 5000 objects Lc cleaning solution Ac Cleaning Air [Prior art documents] [Patent documents]

[0110] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-035031

Claims

1. a head including a nozzle for ejecting liquid, a liquid chamber communicating with the nozzle via a communication port, a nozzle surface having the nozzle, and a valve body for opening and closing the communication port; a cleaning device having a cleaning nozzle that supplies a cleaning liquid to the nozzle surface, the cleaning liquid is supplied to the nozzle surface in a state where the valve body closes the communication port, A liquid ejection system comprising a sealing member that enables a sealed portion to be formed with respect to the nozzle face.

2. A liquid ejection system as described in Claim 1, characterized in that when the type of liquid is changed, the nozzle surface is cleaned after the cleaning device has discharged the liquid remaining in the nozzle before the change.

3. A first cleaning liquid removal means for removing the cleaning liquid supplied to the nozzle surface while the sealing portion is formed on the nozzle surface; 3. The liquid ejection system according to claim 1, further comprising: a second cleaning liquid removal unit that removes the cleaning liquid supplied to the nozzle surface when the sealed portion is not formed on the nozzle surface.

4. 4. The liquid ejection system according to claim 3, wherein the second cleaning liquid removal means uses air that is blown toward the nozzle surface.

5. 4. The liquid ejection system according to claim 3, wherein the second cleaning liquid removal means is an absorbent capable of absorbing the liquid.

6. A head comprising a nozzle for ejecting liquid, a liquid chamber communicating with the nozzle via a communication port, a nozzle surface having the nozzle, and a valve body for opening and closing the communication port; a cleaning device having a cleaning nozzle that supplies a cleaning liquid to the nozzle surface, the cleaning liquid is supplied to the nozzle surface in a state where the valve body closes the communication port, A liquid ejection system characterized in that, when the type of the liquid is changed, the nozzle surface is cleaned after the cleaning device has discharged the liquid remaining in the nozzles before the change.

7. A liquid ejection system described in any one of claims 1 to 6, characterized in that the cleaning nozzle is installed at a position other than on a normal line drawn from the center of the nozzle during cleaning.

8. A liquid ejection system described in any one of claims 1 to 7, characterized in that the nozzle surface is installed so as to intersect with a horizontal plane, and the cleaning nozzle is installed above the direction of gravity relative to a perpendicular line to the nozzle surface.

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