Coating device and coating method

Abstract

To keep appropriate circulating pressure of a liquid to be discharged.SOLUTION: A coating device comprises a retention unit, a robot unit, a first flow path, a second flow path, an acquisition unit, and a control unit. The retention unit retains a liquid to be supplied to a droplet ejection unit. The robot unit operates the droplet ejection unit. The first flow path allows communication between the retention unit and the droplet ejection unit and is for channeling the liquid retained in the retention unit into the droplet ejection unit. The second flow path allows communication between the retention unit and the droplet ejection unit and is for returning the liquid that has flowed into the droplet ejection unit to the retention unit. The acquisition unit acquires information relating to the operation of the droplet ejection unit from a program for controlling the operation of the robot unit. The control unit controls the circulating pressure of the liquid circulating between the retention unit and the droplet ejection unit. The control unit controls the circulating pressure on the basis of the information relating to the operation.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The disclosed embodiments relate to a painting apparatus and a painting method. [Background technology]

[0002] 2. Description of the Related Art Known printing devices include inkjet printers and inkjet plotters that use an inkjet recording method. These inkjet printing devices are equipped with a droplet ejection head for ejecting liquid.

[0003] Furthermore, with regard to inkjet printing devices, a technique for controlling the pressure of the liquid supplied to the droplet ejection head has been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-12432 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional droplet ejection heads are required to flexibly respond to changes in usage patterns and maintain an appropriate circulation pressure for the ejected liquid.

[0006] One aspect of the embodiment has been made in view of the above, and aims to provide a coating device and a coating method that can maintain an appropriate circulation pressure of the discharged liquid. [Means for solving the problem]

[0007] A coating device according to one aspect of the embodiment includes a storage unit, a robot unit, a first flow path, a second flow path, an acquisition unit, and a control unit. The storage unit stores liquid to be supplied to the droplet discharge unit. The robot unit operates the droplet discharge unit. The first flow path connects the storage unit and the droplet discharge unit and is a flow path for causing the liquid stored in the storage unit to flow into the droplet discharge unit. The second flow path connects the storage unit and the droplet discharge unit and is a flow path for causing the liquid that has flowed into the droplet discharge unit to return to the storage unit. The acquisition unit acquires information regarding the operation of the droplet discharge unit from a program that controls the operation of the robot unit. The control unit controls the circulation pressure of the liquid circulating between the storage unit and the droplet discharge unit. The control unit controls the circulation pressure based on the information regarding the operation. [Effects of the Invention]

[0008] According to one aspect of the embodiment, the circulation pressure of the liquid to be ejected can be maintained at an appropriate level. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the external configuration of a droplet ejection system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating changes in liquid pressure inside the droplet ejection head according to the embodiment. [Figure 3] FIG. 3 is a perspective view that schematically shows the external configuration of the droplet ejection head according to the embodiment. [Figure 4] FIG. 4 is a plan view of the droplet ejection head according to the embodiment. [Figure 5] FIG. 5 is a diagram showing a schematic view of a flow path inside the droplet ejection head according to the embodiment. [Figure 6] FIG. 6 is a block diagram showing an example of the functional configuration of the droplet ejection system according to the embodiment. [Figure 7] FIG. 7 is a diagram schematically showing a circulation mechanism of a circulation device in a droplet ejection system according to an embodiment. [Figure 8] FIG. 8 is a diagram showing an outline of pressure adjustment information according to the embodiment. [Figure 9] FIG. 9 is a diagram for explaining a method of controlling the first proportional valve and the second proportional valve based on the position of the droplet ejection head according to the embodiment. [Figure 10] FIG. 10 is a diagram for explaining a method of controlling the first proportional valve and the second proportional valve based on the vertical acceleration acting on the droplet ejection head according to the embodiment. [Figure 11] FIG. 11 is a diagram for explaining a method of controlling the first proportional valve and the second proportional valve based on the horizontal acceleration acting on the droplet ejection head according to the embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of a processing procedure of the droplet ejection system according to the embodiment. [Figure 13] FIG. 13 is a block diagram showing an example of the functional configuration of a droplet ejection system according to another embodiment. [Figure 14] FIG. 14 is a diagram showing an outline of second pressure adjustment information according to another embodiment. [Figure 15] FIG. 15 is a flowchart showing an example of a processing procedure of a droplet ejection system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the coating apparatus and coating method disclosed herein will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments shown below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from reality. Furthermore, the dimensional relationships and ratios may differ between the drawings.

[0011] Furthermore, the embodiments can be combined as appropriate within the scope of not causing any contradiction in the processing content. Furthermore, the same components in the following embodiments are denoted by the same reference numerals, and redundant explanations will be omitted.

[0012] In the following embodiments, as an example of the coating device disclosed in the present application, a droplet ejection system in which a droplet ejection head that ejects liquid (or droplets) by an inkjet method is mounted on a robot arm will be described. The coating device disclosed in the present application can be applied to various devices that eject liquid (or droplets) by an inkjet method, such as inkjet printers and inkjet plotters that use the inkjet recording method.

[0013] <External configuration example of droplet ejection system> The external configuration of a droplet ejection system according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the external configuration of a droplet ejection system according to an embodiment.

[0014] As shown in FIG. 1, the droplet discharge system 1 includes a robot arm (an example of a robot section) 100, a control unit 120, a circulation device 200, and a droplet discharge head 300.

[0015] The robot arm 100 is mounted on a base 10, which is placed on a horizontal floor surface, for example, indoors or outdoors. The robot arm 100 has an arm section 110. The arm section 110 is composed of multiple parts assembled so that they can bend, stretch, and rotate freely. The arm section 110 can operate the droplet discharge head 300 (and the circulation device 200) mounted on the tip of the arm section 110 in accordance with commands from the control unit 120. For example, the arm section 110 can move the droplet discharge head 300 (and the circulation device 200) mounted on the tip of the arm section 110 in accordance with commands from the control unit 120. This allows the arm section 110 to change the position of the droplet discharge head 300 (and the circulation device 200). Furthermore, for example, the arm section 110 can rotate the droplet discharge head 300 (and the circulation device 200) around a predetermined rotation axis (e.g., the Y-axis or the Z-axis) in accordance with commands from the control unit 120. This allows the arm section 110 to change the orientation, angle, and other posture of the droplet discharge head 300 (and circulation device 200). Furthermore, for example, the arm section 110 can perform various operations including swinging, tilting, and inverting the droplet discharge head 300 (and circulation device 200) in accordance with commands from the control unit 120. The arm section 110 illustrated in FIG. 1 is not particularly limited to the configuration shown in FIG. 1, as long as it has a degree of freedom that allows the position and posture of the droplet discharge head 300 to be changed.

[0016] The control unit 120 is built into, for example, the robot arm 100 (arm section 110). The control unit 120 may be mounted on an external device independent of the robot arm 100 and communicatively connected to the robot arm 100. The control unit 120 controls the operation of the arm section 110 by outputting commands for controlling the operation of the arm section 110 to an actuator or the like that drives the arm section 110. The control unit 120 includes a control device 121 (see FIG. 6) such as a processor and a storage device 122 (see FIG. 6) such as a memory. The storage device 122 stores, for example, a first control program 131 (see FIG. 6) that controls the operation of the robot arm 100, a second control program (see FIG. 6) for controlling the operation related to the discharge of the droplet discharge head 300 (hereinafter also referred to as the discharge operation), and the like. The control device 121 controls the operation of the robot arm 100 (arm section 110) based on the programs, data, and the like stored in the storage device 122.

[0017] The robot arm 100 can change the position of the droplet discharge head 300 in the vertical direction (Z-axis direction) by using the arm unit 110 to move the circulation device 200 and the droplet discharge head 300 mounted on the tip of the arm unit 110 along a predetermined vertical axis (Z-axis). As a result, the circulation device 200 and the droplet discharge head 300 can be oriented such that the liquid discharge surface 300SF of the droplet discharge head 300 faces parallel to the spray surface 50SF of the target object 50, as shown in FIG. 1, for example. Furthermore, the robot arm 100 can rotate the circulation device 200 and the droplet discharge head 300 mounted on the tip of the arm unit 110 around a predetermined rotation axis using the arm unit 110. As a result, the circulation device 200 and the droplet discharge head 300 can be swapped between their longitudinal and lateral positions, or their upside-down positions can be reversed, for example.

[0018] The circulation device 200 is installed at the tip of the arm unit 110 of the robot arm 100. The circulation device 200 supplies liquid to the droplet discharge head 300 while controlling the circulation pressure of the liquid circulating between the circulation device 200 and the droplet discharge head 300. The droplet discharge head 300 is assembled to the circulation device 200 installed at the tip of the arm unit 110 of the robot arm 100. The droplet discharge head 300 functions as a droplet discharge unit that discharges liquid onto the target object 50.

[0019] The circulation pressure of the liquid supplied to the droplet ejection head 300 is affected by the movement of the droplet ejection head 300 by the robot arm 100. When the robot arm 100 moves the droplet ejection head 300 and the position of the droplet ejection head 300 changes, the circulation pressure (pressure) of the liquid inside the droplet ejection head 300 changes, for example, as shown in FIG. 2. FIG. 2 is a diagram illustrating the change in the pressure of the liquid inside the droplet ejection head according to the embodiment. When the circulation pressure (pressure) of the liquid inside the droplet ejection head 300 changes, there is a possibility that the liquid will not be ejected stably from the droplet ejection head 300. In view of these problems, the present application proposes a droplet ejection system 1 that can flexibly respond to changes in the position of the droplet ejection head 300 and maintain an appropriate circulation pressure of the ejected liquid.

[0020] <Configuration example of droplet ejection head> A droplet ejection head 300 according to an embodiment will be described with reference to Figures 3 to 5. Figure 3 is a perspective view schematically showing the external configuration of the droplet ejection head according to an embodiment. Figure 4 is a plan view of the droplet ejection head according to an embodiment. Figure 5 is a view schematically showing a flow path inside the droplet ejection head according to an embodiment.

[0021] 3, the droplet ejection head 300 has a housing including a box-shaped member 310 and a substantially flat plate-shaped member 320. The housing of the droplet ejection head 300 is provided with a first flow path RT1 for supplying liquid from the circulation device 200 to the inside of the head, and a second flow path RT2 for returning liquid recovered inside the head to the circulation device 200. As shown in FIG. 3 or 4, the member 320 of the droplet ejection head 300 has a supply port 321 through which liquid is supplied to the inside of the head via the first flow path RT1, and a recovery port 322 through which liquid is recovered from the inside of the head via the second flow path RT2.

[0022] As shown in FIG. 4, the droplet ejection head 300 includes a supply reservoir 301 , a supply manifold 302 , a recovery manifold 303 , a recovery reservoir 304 , and an element 305 .

[0023] The supply reservoir 301 has an elongated shape extending in the longitudinal direction (Y-axis direction) of the droplet ejection head 300, and is connected to the supply manifold 302. The supply reservoir 301 has a flow path therein. As shown in FIG. 4 or 5 , liquid is supplied to the supply reservoir 301 through the first flow path RT1 and the supply port 321, and the liquid stored in the flow path of the supply reservoir 301 is sent to the supply manifold 302.

[0024] The supply manifold 302 has an elongated shape that extends in the short direction (X-axis direction) of the droplet ejection head 300 up to just before the recovery reservoir 304. The supply manifold 302 has therein a flow path that communicates with the flow path of the supply reservoir 301 and with the element 305. As shown in FIG. 4 or 5 , the liquid that is sent from the supply reservoir 301 to the supply manifold 302 is sent from the supply manifold 302 to the element 305.

[0025] The collection manifold 303 has an elongated shape that extends in the short direction (X-axis direction) of the droplet ejection head 300 up to just before the supply reservoir 301. The collection manifold 303 has an internal flow path that communicates with the flow path of the collection reservoir 304 and the element 305. As shown in FIG. 4 or 5, liquid that is not ejected to the outside from the element 305 (ejection hole 305h) is sent to the collection manifold 303.

[0026] The recovery reservoir 304 has an elongated shape extending in the longitudinal direction (Y-axis direction) of the droplet ejection head 300, and is connected to the recovery manifold 303. The recovery reservoir 304 has a flow path therein. As shown in FIG. 4 or 5, the liquid that is sent from the recovery manifold 303 to the recovery reservoir 304 and stored in the flow path of the recovery reservoir 304 is sent back to the circulation device 200 via the recovery port 322 and the second flow path RT2.

[0027] The element 305 has a discharge hole 305h. The element 305, for example, sucks liquid from the supply manifold 302 by negative pressure generated in a pressure chamber (not shown), and discharges the sucked liquid from the discharge hole 305h toward the target object 50 by positive pressure generated in a pressure chamber (not shown).

[0028] <Example of functional configuration of droplet ejection system> Next, an example of the functional configuration of the droplet ejection system 1 according to the embodiment will be described. Fig. 6 is a block diagram showing an example of the functional configuration of the droplet ejection system according to the embodiment. Fig. 7 is a diagram schematically showing the circulation mechanism of the circulation device in the droplet ejection system according to the embodiment.

[0029] Note that FIG. 6 shows an example of the functional configuration of the droplet ejection system 1 according to the embodiment, and the configuration does not need to be particularly limited to the example shown in FIG. 6 as long as it can realize the various functions of the droplet ejection system 1 according to the embodiment. Also, FIG. 6 shows the components of the droplet ejection system 1 according to the embodiment as functional blocks, and does not include descriptions of other general components. Also, the components of the droplet ejection system 1 shown in FIG. 6 are conceptual functional components, are not limited to the example shown in FIG. 6, and do not necessarily need to be physically configured as shown. For example, the specific form of distribution and integration of the functional blocks is not limited to that shown, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0030] 6, the droplet discharging system 1 includes a circulation device 200. The circulation device 200 includes a tank 201, a discharge pump 202, a suction pump 203, a first proportional valve 204, a second proportional valve 205, and a heater 206. The circulation device 200 also includes an input / output interface 207, a first pressure sensor 208, a second pressure sensor 209, a third pressure sensor 210, a fourth pressure sensor 211, and a flow meter 212. The circulation device 200 also includes a storage 214 and a processor 215. Note that the storage 214 and the processor 215 may be installed independently of the circulation device 200. The droplet discharging system 1 also includes a robot arm 100, a control unit 120, and a droplet discharging head 300.

[0031] 7, the circulation device 200 includes a first flow path RT1 and a second flow path RT2. The first flow path RT1 communicates between the tank 201 and the droplet discharge head 300, and is a flow path for allowing the liquid stored in the tank 201 to flow into the droplet discharge head 300. The second flow path RT2 communicates between the tank 201 and the droplet discharge head 300, and is a flow path for returning the liquid that has flowed into the droplet discharge head 300 to the tank 201. Liquid that is not discharged from the droplet discharge head 300 to the outside and is collected within the droplet discharge head 300 is sent back to the tank 201 through the second flow path RT2. The first flow path RT1 and the second flow path RT2 can be implemented, for example, by piping made of a predetermined material that does not interact with components of the liquid. The processor 215 of the circulation device 200 having these components controls the circulation pressure of the liquid circulating clockwise between the tank 201 and the droplet ejection head 300, as shown in FIG.

[0032] The tank 201 stores the liquid to be supplied to the droplet discharge head 300. The tank 201 functions as a storage unit that stores the liquid to be supplied to the droplet discharge head 300.

[0033] The discharge pump 202 supplies the liquid stored in the tank 201 to the droplet discharge head 300 through the first flow path RT1. The discharge pump 202 generates a positive pressure for sending the liquid stored in the tank 201 to the droplet discharge head 300. The discharge pump 202 can send the liquid stored in the tank 201 to the droplet discharge head 300 at, for example, a preset constant supply pressure.

[0034] The suction pump 203 supplies the liquid recovered in the droplet discharge head 300 to the tank 201 through the second flow path RT2. The suction pump 203 generates negative pressure to suck the liquid recovered in the droplet discharge head 300 and return it to the tank 201. The suction pump 203 can send the liquid sucked from the droplet discharge head 300 to the tank 201 at, for example, a preset constant recovery pressure.

[0035] The discharge pump 202 and the suction pump 203 can be implemented by a rotary pump such as a gear pump or a positive displacement pump such as a diaphragm pump.

[0036] The first proportional valve 204 is interposed in the first flow path RT1 between the tank 201 and the droplet discharging head 300, and functions as a first valve unit that proportionally controls the flow rate of the liquid supplied to the droplet discharging head 300. The first proportional valve 204 can continuously change the cross-sectional area of ​​the liquid flow path between 0 and 100%, and controls the flow rate of the liquid to a desired flow rate. For example, the first proportional valve 204 can reduce the supply pressure when supplying the liquid to the droplet discharging head 300 by reducing the cross-sectional area of ​​the liquid flow path. On the other hand, the first proportional valve 204 can increase the supply pressure when supplying the liquid to the droplet discharging head 300 by increasing the cross-sectional area of ​​the liquid flow path.

[0037] The second proportional valve 205 is interposed in the second flow path RT2 between the tank 201 and the droplet discharging head 300, and functions as a second valve unit that proportionally controls the flow rate of the liquid delivered from the droplet discharging head 300 to the tank 201. Similar to the first proportional valve 204, the second proportional valve 205 can continuously change the cross-sectional area of ​​the liquid flow path between 0 and 100%, and controls the flow rate of the liquid to a desired flow rate. For example, the second proportional valve 205 can reduce the recovery pressure when recovering the liquid from the droplet discharging head 300 by reducing the cross-sectional area of ​​the liquid flow path. On the other hand, the second proportional valve 205 can increase the recovery pressure when recovering the liquid from the droplet discharging head 300 by increasing the cross-sectional area of ​​the liquid flow path.

[0038] The first proportional valve 204 and the second proportional valve 205 can be implemented by an electromagnetic proportional switching valve or a pneumatic proportional switching valve.

[0039] The heater 206 is provided in the first flow path RT1 or adjacent to the first flow path RT1, and heats the liquid flowing through the first flow path RT1.

[0040] The input / output interface 207 exchanges various types of information with the control unit 120 of the robot arm 100. The input / output interface 207 can receive, for example, a signal instructing the start of liquid ejection and a signal instructing the end of liquid ejection from the control unit 120. Furthermore, the input / output interface 207 can acquire information related to the operation of the droplet ejection head 300 from a first control program 131 stored in the storage device 122 of the control unit 120 under the control of the processor 215. Information related to the operation of the droplet ejection head 300 includes, for example, numerical values ​​related to the movement of the droplet ejection head 300. Examples of numerical values ​​related to the movement of the droplet ejection head 300 include the vertical position of the droplet ejection head 300, the vertical acceleration acting on the droplet ejection head 300, and the horizontal acceleration acting on the droplet ejection head 300. Furthermore, the information relating to the operation of the droplet discharging head 300 may be, for example, numerical values ​​relating to various operations including swinging, tilting, and inversion of the droplet discharging head 300. The input / output interface 207 functions as an acquisition unit that acquires information relating to the operation of the droplet discharging head 300 from the first control program 131 that controls the operation of the robot arm 100 that operates the droplet discharging head 300.

[0041] The first pressure sensor 208 measures the pressure of the liquid supplied from the tank 201 to the droplet discharge head 300 by the discharge pump 202. The first pressure sensor 208 measures the pressure downstream of the discharge pump 202 in the circulation direction of the liquid in the circulation device 200. The first pressure sensor 208 sends the measurement result to the processor 215.

[0042] The second pressure sensor 209 measures the pressure of the liquid sucked from the droplet ejection head 300 by the suction pump 203 and delivered to the tank 201. The second pressure sensor 209 measures the pressure upstream of the suction pump 203 in the circulation direction of the liquid in the circulation device 200. The second pressure sensor 209 sends the measurement result to the processor 215.

[0043] The third pressure sensor 210 functions as a first pressure measurement unit that measures, as a supply pressure, the pressure of the liquid flowing between the first proportional valve 204 and the droplet discharging head 300 through the first flow path RT1. The third pressure sensor 210 measures the pressure of the liquid that has passed through the first proportional valve 204 and is about to flow into the droplet discharging head 300. In other words, the third pressure sensor 210 measures, as the supply pressure, the pressure downstream of the first proportional valve 204 in the circulation direction of the liquid in the circulation device 200. The third pressure sensor 210 sends the measurement result to the processor 215.

[0044] The fourth pressure sensor 211 functions as a second pressure measurement unit that measures, as a recovery pressure, the pressure of the liquid flowing between the second proportional valve 205 and the droplet discharging head 300 through the second flow path RT2. The fourth pressure sensor 211 measures the pressure of the liquid immediately after it is sent from the droplet discharging head 300 toward the tank 201 and before it passes through the second proportional valve 205. In other words, the fourth pressure sensor 211 measures, as the recovery pressure, the pressure upstream of the second proportional valve 205 in the circulation direction of the liquid in the circulation device 200. The fourth pressure sensor 211 sends the measurement result to the processor 215.

[0045] The flow meter 212 measures the flow rate of the liquid supplied to the droplet ejection head 300. The flow meter 212 sends the measurement results to the processor 215.

[0046] The storage 214 stores programs and data necessary for various processes of the droplet discharge system 1 (here, the circulation device 200). The storage 214 stores, for example, pump control information 241 and pressure adjustment information 242.

[0047] The pump control information 241 is preset data for pump control. The pump control data includes, for example, a target value for the pressure (positive pressure) applied to the liquid when the discharge pump 202 discharges the liquid, and a target value for the pressure (negative pressure) applied to the liquid when the suction pump 203 sucks the liquid. When considering the discharge of liquid from the droplet discharge head 300, the target value for the positive pressure of the discharge pump 202 is preset to, for example, a value that is about 1.2 to 3 times higher than the pressure when the liquid is supplied to the droplet discharge head 300. On the other hand, the target value for the negative pressure of the suction pump 203 is preset to a value that is about 1.2 to 3 times lower than the pressure when the liquid is supplied to the droplet discharge head 300.

[0048] The pressure adjustment information 242 is data that associates adjustment values ​​for the supply pressure and recovery pressure for suppressing changes in the liquid pressure inside the droplet ejection head 300 with the magnitude of a numerical value related to the movement of the droplet ejection head 300. Fig. 8 is a diagram showing an overview of the pressure adjustment information according to this embodiment.

[0049] As shown in FIG. 8, the pressure adjustment information 242 includes an item for "numerical values ​​related to head movement," an item for "adjustment value (supply pressure)," and an item for "adjustment value (recovery pressure)," and these items correspond to each other. The item for "numerical values ​​related to head movement" stores numerical values ​​related to the movement of the droplet ejection head 300, such as the vertical position of the droplet ejection head 300, the vertical acceleration acting on the droplet ejection head 300, or the horizontal acceleration acting on the droplet ejection head 300. The item for "adjustment value (supply pressure)" stores a target value (hereinafter also referred to as "adjustment value") for adjusting the supply pressure. The item for "adjustment value (recovery pressure)" stores a target value (hereinafter also referred to as "adjustment value") for adjusting the recovery pressure.

[0050] As the vertical position of the droplet ejection head 300 changes, a head pressure acts on the liquid circulating inside the head, changing the circulating pressure of the liquid inside the head, which can result in unstable ejection of the liquid from the droplet ejection head 300. Therefore, through experiments, simulations, etc., a relationship between the adjustment values ​​of the supply pressure and the recovery pressure that will keep the pressure of the liquid inside the head constant in response to changes in the vertical position of the droplet ejection head 300 is determined in advance. The supply pressure is obtained from the measurement results by the third pressure sensor 210. The recovery pressure is obtained from the measurement results by the fourth pressure sensor 211. Adjustment values ​​of the supply pressure and the recovery pressure are associated with the magnitude of the numerical value of the vertical position of the droplet ejection head 300 and stored in the pressure adjustment information 242.

[0051] The pressure adjustment information 242 may be prepared according to the type of numerical value related to the movement of the droplet ejection head 300. In other words, the pressure adjustment information 242 may be prepared separately for each of the vertical position of the droplet ejection head 300, the vertical acceleration acting on the droplet ejection head 300, and the horizontal acceleration acting on the droplet ejection head 300.

[0052] The processor 215 executes various processes in the droplet ejection system 1 (here, the circulation device 200) based on the programs, data, etc. stored in the storage 214. The processor 215 reads and executes the computer programs stored in the storage 214, thereby realizing various functions for controlling each part of the droplet ejection system 1 (here, the circulation device 200).

[0053] (Pump control) The processor 215 adjusts the positive pressure applied to the liquid when the discharge pump 202 pumps out the liquid so as to maintain a constant pressure based on the measurement results of the first pressure sensor 208 and the measurement results of the third pressure sensor 210. For example, the processor 215 adjusts the positive pressure of the discharge pump 202 so as to maintain the pressure of the liquid obtained from the measurement results of the first pressure sensor 208 at a pressure that is approximately 1.2 to 3 times greater than the pressure of the liquid obtained from the measurement results of the third pressure sensor 210.

[0054] Furthermore, processor 215 adjusts the negative pressure applied to the liquid when suction pump 203 suctions the liquid so as to maintain a constant pressure based on the measurement results of second pressure sensor 209 and fourth pressure sensor 211. For example, processor 215 adjusts the negative pressure of suction pump 203 so that the liquid pressure obtained from the measurement result of second pressure sensor 209 is maintained at a pressure that is approximately 1.2 to 3 times lower than the liquid pressure obtained from the measurement result of fourth pressure sensor 211.

[0055] The processor 215 circulates the liquid between the tank 201 and the droplet ejection head 300 by adjusting the pressure difference between the positive pressure applied to the liquid by the ejection pump 202 and the negative pressure applied to the liquid by the suction pump 203 to maintain a constant pressure.

[0056] (Proportional valve control) Processor 215 controls first proportional valve 204 and second proportional valve 205 to adjust the supply pressure and recovery pressure based on the numerical values ​​acquired by input / output interface 207. A control method for first proportional valve 204 and second proportional valve 205 will be described below with reference to Figs. 9 to 11.

[0057] 9 is a diagram illustrating a method for controlling the first proportional valve and the second proportional valve based on the position of the droplet ejection head according to the embodiment. The first diagram from the top of FIG. 9 schematically illustrates an example of the relationship between time and the vertical position of the droplet ejection head 300. The second and third diagrams from the top of FIG. 9 also schematically illustrate an example of the relationship between time and the adjustment values ​​of the supply pressure and the recovery pressure. The fourth diagram from the top of FIG. 9 also schematically illustrates an example of the relationship between time and the circulating pressure of the liquid inside the droplet ejection head 300. Here, the droplet ejection head 300 is oriented such that the liquid ejection surface 300SF faces vertically downward (see FIG. 1).

[0058] Using FIG. 9, the control when the droplet ejection head 300 moves at a constant speed in the vertical direction will be described.

[0059] As shown in Figure 9, when the droplet ejection head 300 moves and its position changes, it is predicted that the hydraulic head pressure acts on the liquid circulating inside the head, causing a change in the pressure circulating the liquid inside the droplet ejection head 300. In Figure 9, the change in the pressure circulating the liquid inside the droplet ejection head 300 due to the influence of the hydraulic head pressure is shown by the dashed line graph. If the pressure circulating the liquid inside the droplet ejection head 300 changes, there is a possibility that the liquid will not be ejected stably from the droplet ejection head 300.

[0060] Therefore, the processor 215 controls the input / output interface 207 to acquire the vertical position of the droplet ejection head 300. Specifically, the input / output interface 207 acquires the vertical position of the droplet ejection head 300 from the first control program 131 as a numerical value related to the movement of the droplet ejection head 300.

[0061] The processor 215 adjusts the supply pressure and recovery pressure so that the liquid circulation pressure (pressure) inside the droplet discharging head 300, which changes depending on the acquired position of the droplet discharging head 300, becomes constant. Here, "the liquid circulation pressure (pressure) becomes constant" is a concept that includes not only the case where the liquid pressure becomes strictly constant, but also the case where the liquid pressure approaches constant. In other words, the processor 215 may adjust the supply pressure and recovery pressure so that the liquid circulation pressure (pressure) inside the droplet discharging head 300 approaches constant. For example, if the pressure inside the head increases, the processor 215 may adjust the supply pressure and recovery pressure so that the circulation pressure decreases, and if the pressure inside the head decreases, the processor 215 may adjust the supply pressure and recovery pressure so that the circulation pressure increases.

[0062] In the example shown in FIG. 9 , it is predicted that the higher the position of the droplet discharging head 300, the more the liquid circulation pressure (pressure) inside the droplet discharging head 300 decreases due to the influence of hydraulic head pressure. To maintain a constant liquid circulation pressure (pressure) inside the droplet discharging head 300, it is necessary to increase both the supply pressure and the recovery pressure to counteract the influence of hydraulic head pressure. The processor 215 refers to the pressure adjustment information 242 and identifies adjustment values ​​for each of the supply pressure and the recovery pressure corresponding to the acquired position of the droplet discharging head 300. The adjustment values ​​for each of the supply pressure and the recovery pressure increase as the position of the droplet discharging head 300 increases. Then, while referring to the measurement results of the third pressure sensor 210, the processor 215 increases the flow path cross-sectional area of ​​the first proportional valve 204, thereby increasing the flow rate of the fluid passing through the first proportional valve 204, in order to increase the supply pressure to a target pressure based on the identified adjustment values. Meanwhile, the processor 215, while referring to the measurement results of the fourth pressure sensor 211, increases the flow path cross-sectional area of ​​the second proportional valve 205 and increases the flow rate of fluid passing through the second proportional valve 205 in order to increase the recovery pressure to the target pressure based on the identified adjustment value.

[0063] 9, it is predicted that the lower the position of the droplet discharging head 300, the greater the liquid circulation pressure (pressure) inside the droplet discharging head 300 due to the influence of hydraulic head pressure. To maintain a constant liquid circulation pressure (pressure) inside the droplet discharging head 300, it is necessary to reduce both the supply pressure and the recovery pressure to counteract the influence of hydraulic head pressure. The processor 215 refers to the pressure adjustment information 242 to identify adjustment values ​​for the supply pressure and the recovery pressure corresponding to the acquired position of the droplet discharging head 300. The adjustment values ​​for the supply pressure and the recovery pressure decrease as the position of the droplet discharging head 300 decreases. The processor 215 then refers to the measurement results of the third pressure sensor 210 to reduce the supply pressure to a target pressure based on the identified adjustment values, thereby reducing the flow rate of the fluid passing through the first proportional valve 204 by narrowing the flow path cross-sectional area of ​​the first proportional valve 204. Meanwhile, the processor 215, while referring to the measurement results of the fourth pressure sensor 211, narrows the flow path cross-sectional area of ​​the second proportional valve 205 and reduces the flow rate of fluid passing through the second proportional valve 205 in order to reduce the recovery pressure to the target pressure based on the identified adjustment value.

[0064] In this way, processor 215 can increase or decrease the flow rate of fluid passing through first proportional valve 204 and second proportional valve 205 depending on the vertical position of droplet ejection head 300. This allows processor 215 to maintain a constant circulation pressure of the liquid inside droplet ejection head 300.

[0065] 10 is a diagram illustrating a method for controlling the first proportional valve and the second proportional valve based on the vertical acceleration acting on the droplet discharge head according to the embodiment. The first diagram from the top of FIG. 10 schematically illustrates an example of the relationship between time and the vertical position of the droplet discharge head 300. The second diagram from the top of FIG. 10 also schematically illustrates an example of the relationship between time and the vertical acceleration acting on the droplet discharge head 300. The third and fourth diagrams from the top of FIG. 10 also schematically illustrate an example of the relationship between time and the adjustment values ​​of the supply pressure and the recovery pressure. Here, the droplet discharge head 300 is oriented such that the liquid discharge surface 300SF faces vertically downward (see FIG. 1).

[0066] Using FIG. 10, the control when the droplet ejection head 300 moves while accelerating and decelerating in the vertical direction will be described.

[0067] 10, when the droplet discharge head 300 moves and the acceleration of the droplet discharge head 300 changes, it is predicted that the head pressure acts on the liquid circulating inside the head, causing a change in the circulation pressure (pressure) of the liquid inside the droplet discharge head 300. If the circulation pressure (pressure) of the liquid inside the droplet discharge head 300 changes, there is a possibility that the liquid will not be discharged stably from the droplet discharge head 300.

[0068] Therefore, the processor 215 controls the input / output interface 207 to acquire the vertical acceleration acting on the droplet ejection head 300. Specifically, the input / output interface 207 acquires the vertical acceleration acting on the droplet ejection head 300 from the first control program 131 as a numerical value related to the movement of the droplet ejection head 300.

[0069] The processor 215 adjusts the supply pressure and recovery pressure so that the circulation pressure (pressure) of the liquid inside the droplet ejection head 300, which changes in accordance with the acquired vertical acceleration, is kept constant.

[0070] In the example shown in FIG. 10 , it is predicted that the greater the vertical upward acceleration of the droplet discharging head 300, the greater the liquid circulation pressure (pressure) inside the droplet discharging head 300 due to the influence of hydraulic head pressure. To maintain a constant liquid circulation pressure (pressure) inside the droplet discharging head 300, it is necessary to reduce both the supply pressure and the recovery pressure to counteract the influence of hydraulic head pressure. The processor 215 refers to the pressure adjustment information 242 to identify adjustment values ​​for the supply pressure and the recovery pressure corresponding to the acquired vertical acceleration. The adjustment values ​​for the supply pressure and the recovery pressure decrease as the vertical upward acceleration of the droplet discharging head 300 increases. Then, while referring to the measurement results of the third pressure sensor 210, the processor 215 narrows the flow path cross-sectional area of ​​the first proportional valve 204, thereby reducing the flow rate of the fluid passing through the first proportional valve 204, in order to reduce the supply pressure to a target pressure based on the identified adjustment values. Meanwhile, the processor 215, while referring to the measurement results of the fourth pressure sensor 211, narrows the flow path cross-sectional area of ​​the second proportional valve 205 and reduces the flow rate of fluid passing through the second proportional valve 205 in order to reduce the recovery pressure to the target pressure based on the identified adjustment value.

[0071] 10 , it is predicted that the lower the vertical upward acceleration of the droplet discharging head 300, the more the liquid circulation pressure (pressure) inside the droplet discharging head 300 decreases due to the influence of hydraulic head pressure. To maintain a constant liquid circulation pressure (pressure) inside the droplet discharging head 300, it is necessary to increase both the supply pressure and the recovery pressure to counteract the influence of hydraulic head pressure. The processor 215 refers to the pressure adjustment information 242 to identify adjustment values ​​for the supply pressure and the recovery pressure corresponding to the acquired position of the droplet discharging head 300. The adjustment values ​​for the supply pressure and the recovery pressure increase as the vertical upward acceleration of the droplet discharging head 300 decreases. The processor 215 then increases the flow path cross-sectional area of ​​the first proportional valve 204, thereby increasing the flow rate of the fluid passing through the first proportional valve 204, in order to increase the supply pressure to a target pressure based on the identified adjustment values, while referring to the measurement results of the third pressure sensor 210. Meanwhile, the processor 215, while referring to the measurement results of the fourth pressure sensor 211, increases the flow path cross-sectional area of ​​the second proportional valve 205 and increases the flow rate of fluid passing through the second proportional valve 205 in order to increase the recovery pressure to the target pressure based on the identified adjustment value.

[0072] In this way, processor 215 can increase or decrease the flow rate of fluid passing through first proportional valve 204 and second proportional valve 205 in response to the vertical acceleration acting on droplet ejection head 300. This allows processor 215 to maintain a constant circulation pressure of the liquid inside droplet ejection head 300.

[0073] Fig. 11 is a diagram illustrating a method for controlling the first proportional valve and the second proportional valve based on the horizontal acceleration acting on the droplet discharge head according to the embodiment. The first diagram from the top of Fig. 11 schematically illustrates an example of the relationship between time and the horizontal position of the droplet discharge head 300. The second diagram from the top of Fig. 10 schematically illustrates an example of the relationship between time and the horizontal acceleration acting on the droplet discharge head 300. The third and fourth diagrams from the top of Fig. 10 schematically illustrate an example of the relationship between time and the adjustment values ​​of the supply pressure and the recovery pressure. Here, the droplet discharge head 300 is assumed to be oriented such that the liquid discharge surface 300SF faces vertically downward (see Fig. 1).

[0074] Control when the droplet discharge head 300 moves while accelerating and decelerating in the horizontal direction will be described using Fig. 11. Note that in Fig. 11, the horizontal acceleration acting on the droplet discharge head 300 refers to the acceleration in the direction from the downstream side to the upstream side of the liquid flowing inside the droplet discharge head 300. Here, the downstream side refers to the recovery side (i.e., the recovery port 322 side) where the liquid is recovered from the droplet discharge head 300, and the upstream side refers to the supply side (i.e., the supply port 321 side) where the liquid is supplied to the droplet discharge head 300.

[0075] 11, when the droplet discharge head 300 moves and the acceleration of the droplet discharge head 300 changes, it is predicted that the head pressure acts on the liquid circulating inside the head, causing a change in the circulation pressure (pressure) of the liquid inside the droplet discharge head 300. If the circulation pressure (pressure) of the liquid inside the droplet discharge head 300 changes, there is a possibility that the liquid will not be discharged stably from the droplet discharge head 300.

[0076] Therefore, the processor 215 controls the input / output interface 207 to acquire the horizontal acceleration acting on the droplet ejection head 300. Specifically, the input / output interface 207 acquires the horizontal acceleration acting on the droplet ejection head 300 from the first control program 131 as a numerical value related to the movement of the droplet ejection head 300.

[0077] The processor 215 adjusts the supply pressure and recovery pressure so that the liquid circulation pressure (pressure) inside the droplet ejection head 300, which changes depending on the acquired horizontal acceleration, is kept constant.

[0078] In the example shown in FIG. 11 , as the acceleration of the liquid flowing inside the droplet discharging head 300 in the direction from downstream to upstream increases, it is predicted that the pressure on the upstream side of the liquid flowing inside the droplet discharging head 300 will be higher than the pressure on the downstream side due to the influence of hydraulic head pressure. In order to maintain a constant circulation pressure (pressure) of the liquid inside the droplet discharging head 300, it is necessary to decrease the supply pressure and increase the recovery pressure so as to counteract the influence of hydraulic head pressure. The processor 215 refers to the pressure adjustment information 242 to identify adjustment values ​​for each of the supply pressure and recovery pressure corresponding to the acquired horizontal acceleration. The adjustment value for the supply pressure decreases as the acceleration of the liquid flowing inside the droplet discharging head 300 in the direction from downstream to upstream increases. On the other hand, the adjustment value for the recovery pressure increases as the acceleration of the liquid flowing inside the droplet discharging head 300 in the direction from downstream to upstream increases. Then, while referring to the measurement result of the third pressure sensor 210, processor 215 narrows the flow path cross-sectional area of ​​first proportional valve 204 and reduces the flow rate of fluid passing through first proportional valve 204 in order to reduce the supply pressure to the target pressure based on the specified adjustment value. On the other hand, while referring to the measurement result of the fourth pressure sensor 211, processor 215 widens the flow path cross-sectional area of ​​second proportional valve 205 and increases the flow rate of fluid passing through second proportional valve 205 in order to increase the recovery pressure to the target pressure based on the specified adjustment value.

[0079] 11 , as the acceleration of the liquid flowing inside the droplet discharging head 300 in the direction from downstream to upstream decreases, it is predicted that the pressure on the upstream side of the liquid flowing inside the droplet discharging head 300 will be lower than the pressure on the downstream side due to the influence of hydraulic head pressure. In order to maintain a constant circulation pressure (pressure) of the liquid inside the droplet discharging head 300, it is necessary to increase the supply pressure and decrease the recovery pressure so as to counteract the influence of hydraulic head pressure. The processor 215 refers to the pressure adjustment information 242 to identify adjustment values ​​for each of the supply pressure and recovery pressure corresponding to the acquired horizontal acceleration. The adjustment value for the supply pressure increases as the acceleration of the liquid flowing inside the droplet discharging head 300 in the direction from downstream to upstream decreases. On the other hand, the adjustment value for the recovery pressure decreases as the acceleration of the liquid flowing inside the droplet discharging head 300 in the direction from downstream to upstream decreases. Then, while referring to the measurement result of the third pressure sensor 210, processor 215 increases the flow path cross-sectional area of ​​first proportional valve 204 and increases the flow rate of fluid passing through first proportional valve 204 in order to increase the supply pressure to the target pressure based on the specified adjustment value. On the other hand, while referring to the measurement result of the fourth pressure sensor 211, processor 215 narrows the flow path cross-sectional area of ​​second proportional valve 205 and decreases the flow rate of fluid passing through second proportional valve 205 in order to decrease the recovery pressure to the target pressure based on the specified adjustment value.

[0080] In this way, processor 215 can increase or decrease the flow rate of fluid passing through first proportional valve 204 and second proportional valve 205 in response to horizontal acceleration acting on droplet ejection head 300. This allows processor 215 to maintain a constant circulating pressure of the liquid inside droplet ejection head 300.

[0081] <Example of processing procedure for droplet ejection system> An example of a processing procedure of the droplet ejection system 1 according to the embodiment will be described using Fig. 12. Fig. 12 is a flowchart showing an example of a processing procedure of the droplet ejection system according to the embodiment. The processing shown in Fig. 12 is executed by the processor 215. The processing shown in Fig. 12 is repeatedly executed during operation of the droplet ejection system 1.

[0082] 12, the processor 215 controls the input / output interface 207 to obtain numerical values ​​relating to the movement of the droplet ejection head 300 from the first control program 131 (step S101). That is, the input / output interface 207 obtains at least one of the following numerical values: the vertical position of the droplet ejection head 300, the vertical acceleration acting on the droplet ejection head 300, and the horizontal acceleration acting on the droplet ejection head 300.

[0083] The processor 215 refers to the pressure adjustment information 242 and identifies the adjustment values ​​for each of the supply pressure and the recovery pressure corresponding to the acquired numerical values ​​(step S102).

[0084] The processor 215 adjusts the supply pressure and recovery pressure of the liquid circulating between the tank 201 and the droplet ejection head 300 up to the specified adjustment values ​​(step S103), and returns to the processing procedure of step S101.

[0085] <Another embodiment> Another embodiment of the droplet ejection system 1 according to the embodiment will be described with reference to Figures 13 to 15. Figure 13 is a block diagram showing an example of the functional configuration of the droplet ejection system according to the another embodiment. Note that the circulation mechanism of the circulation device 200A in the droplet ejection system 1 according to the another embodiment is similar to the circulation mechanism of the circulation device 200 in the droplet ejection system 1 according to the embodiment shown in Figure 7, and therefore description thereof will be omitted.

[0086] 13, a droplet ejection system 1 according to another embodiment includes a circulation device 200A. The circulation device 200A includes an input / output interface 207A instead of the input / output interface 207 shown in Fig. 6. The circulation device 200A also includes a storage 214A and a processor 215A instead of the storage 214 and the processor 215 shown in Fig. 6.

[0087] 6, the input / output interface 207A exchanges various types of information with the control unit 120 of the robot arm 100. Like the input / output interface 207, the input / output interface 207A can acquire numerical values ​​related to the movement of the droplet ejection head 300 from a first control program 131 stored in the storage device 122 of the control unit 120 under the control of the processor 215. The input / output interface 207A can also acquire the printing rate of the droplet ejection head 300 from a second control program 132 stored in the storage device 122 of the control unit 120 under the control of the processor 215A. This "printing rate" refers to, for example, the ratio (S1 / S2) of the cumulative area S1 of the liquid ejected onto the target object 50 to the area S2 of the spray surface 50SF of the target object 50, and can be calculated from the image data to be printed. The input / output interface 207A functions as an acquisition unit that acquires the printing rate of the droplet ejection head 300 from the second control program 132 that controls the operations related to ejection of the droplet ejection head 300.

[0088] The storage 214A stores programs and data necessary for various processes of the droplet discharge system 1 (here, the circulation device 200A). The storage 214A stores, for example, pump control information 241, first pressure adjustment information 242A, and second pressure adjustment information 243A. The pump control information 241 has the same data structure as the pump control information 241 shown in FIG. 6. Furthermore, the first pressure adjustment information 242A has the same data structure as the pressure adjustment information 242 shown in FIG. 6.

[0089] The second pressure adjustment information 243A is data that associates adjustment values ​​for each of the supply pressure and recovery pressure for suppressing changes in the pressure of the liquid inside the droplet ejection head 300 with each printing rate of the droplet ejection head 300. Fig. 14 is a diagram showing an overview of the second pressure adjustment information according to another embodiment.

[0090] As shown in FIG. 14, the second pressure adjustment information 243A includes an item for "printing rate," an item for "adjustment value (supply pressure)," and an item for "adjustment value (recovery pressure)," and these items are associated with each other. The item for "printing rate" stores the printing rate of the droplet ejection head 300. The item for "adjustment value (supply pressure)" stores a target value (hereinafter also referred to as "adjustment value") for adjusting the supply pressure. The item for "adjustment value (recovery pressure)" stores a target value (hereinafter also referred to as "adjustment value") for adjusting the recovery pressure.

[0091] As the printing rate of the droplet ejection head 300 changes, the circulation pressure (pressure) of the liquid circulating inside the head changes, which may result in unstable ejection of liquid from the droplet ejection head 300. Therefore, through experiments, simulations, etc., the relationship between the adjustment values ​​of the supply pressure and the recovery pressure that will keep the pressure of the liquid inside the head constant in response to changes in the printing rate of the droplet ejection head 300 is determined in advance. The supply pressure is obtained from the measurement results by the third pressure sensor 210. The recovery pressure is obtained from the measurement results by the fourth pressure sensor 211. Then, the adjustment values ​​of the supply pressure and the recovery pressure are associated with each size of the printing rate of the droplet ejection head 300 and stored in the second pressure adjustment information 243A.

[0092] The processor 215A controls the first proportional valve 204 and the second proportional valve 205 based on numerical values ​​acquired by the input / output interface 207A to adjust the supply pressure and the recovery pressure. In parallel with the adjustment of the supply pressure and the recovery pressure based on these numerical values, the processor 215A controls the first proportional valve 204 and the second proportional valve 205 based on the printing rate acquired by the input / output interface 207A to adjust the supply pressure and the recovery pressure. In other words, the processor 215A simultaneously adjusts the supply pressure and the recovery pressure based on numerical values ​​related to the operation of the droplet ejection head 300 and the supply pressure and the recovery pressure based on the printing rate of the droplet ejection head 300. A method for controlling the first proportional valve 204 and the second proportional valve 205 based on the printing rate of the droplet ejection head 300 will be described below.

[0093] When the droplet ejection head 300 moves and its position changes, it is predicted that the head pressure acts on the liquid circulating inside the head, causing a change in the circulation pressure (pressure) of the liquid inside the droplet ejection head 300. Furthermore, when the printing rate of the droplet ejection head 300 changes, it is predicted that the circulation pressure (pressure) of the liquid inside the droplet ejection head 300 will also change. If the circulation pressure (pressure) of the liquid inside the droplet ejection head 300 changes, there is a possibility that the liquid will not be ejected stably from the droplet ejection head 300.

[0094] Therefore, the processor 215A controls the input / output interface 207 to acquire numerical values ​​related to the movement of the droplet ejection head 300. Specifically, the input / output interface 207 acquires the vertical position of the droplet ejection head 300 and the like as numerical values ​​related to the movement of the droplet ejection head 300 from the first control program 131. The processor 215A also controls the input / output interface 207A to acquire the printing rate of the droplet ejection head 300. Specifically, the input / output interface 207A acquires the printing rate of the droplet ejection head 300 from the second control program 132.

[0095] The processor 215A adjusts the supply pressure and recovery pressure so that the circulation pressure (pressure) of the liquid inside the droplet discharge head 300, which changes depending on the acquired position of the droplet discharge head 300, becomes constant. The control method for the first proportional valve 204 and the second proportional valve 205 based on the position of the droplet discharge head 300, etc., is the same as the control method shown in Figures 9 to 11.

[0096] The processor 215A also adjusts the supply pressure and recovery pressure so that the liquid circulation pressure (pressure) inside the droplet ejection head 300, which changes depending on the acquired printing rate of the droplet ejection head 300, remains constant. To maintain the liquid circulation pressure (pressure) inside the droplet ejection head 300 constant, it is necessary to increase both the supply pressure and the recovery pressure to compensate for the lack of liquid supply. The processor 215A refers to the second pressure adjustment information 243A to identify adjustment values ​​for the supply pressure and the recovery pressure corresponding to the acquired printing rate of the droplet ejection head 300. The adjustment values ​​for the supply pressure and the recovery pressure increase as the printing rate of the droplet ejection head 300 increases. The processor 215A then increases the flow path cross-sectional area of ​​the first proportional valve 204, thereby increasing the flow rate of the fluid passing through the first proportional valve 204, in order to increase the supply pressure to a target pressure based on the identified adjustment values, while referring to the measurement results of the third pressure sensor 210. Meanwhile, the processor 215A, while referring to the measurement results of the fourth pressure sensor 211, increases the flow path cross-sectional area of ​​the second proportional valve 205 and increases the flow rate of fluid passing through the second proportional valve 205 in order to increase the recovery pressure to the target pressure based on the identified adjustment value.

[0097] In this way, the processor 215A can increase or decrease the flow rate of the fluid passing through the first proportional valve 204 and the second proportional valve 205 according to the printing rate of the droplet ejection head 300. This allows the processor 215A to maintain a constant circulation pressure (pressure) of the liquid inside the droplet ejection head 300.

[0098] An example of a processing procedure of a droplet ejection system 1 according to another embodiment will be described using Fig. 15. Fig. 15 is a flowchart showing an example of a processing procedure of a droplet ejection system according to another embodiment. The processing shown in Fig. 15 is executed by the processor 215A. The processing shown in Fig. 15 is repeatedly executed during operation of the droplet ejection system 1.

[0099] 15, the processor 215A controls the input / output interface 207A to obtain numerical values ​​relating to the movement of the droplet ejection head 300 from the first control program 131 (step S201). That is, the input / output interface 207A obtains at least one of the following numerical values: the vertical position of the droplet ejection head 300, the vertical acceleration acting on the droplet ejection head 300, and the horizontal acceleration acting on the droplet ejection head 300.

[0100] The processor 215A controls the input / output interface 207A to obtain the printing rate of the droplet ejection head 300 from the second control program 132 (step S202).

[0101] The processor 215A refers to the first pressure adjustment information 242A and identifies the adjustment values ​​for each of the supply pressure and the recovery pressure corresponding to the acquired numerical values ​​(step S203).

[0102] The processor 215A adjusts the supply pressure and recovery pressure of the liquid circulating between the tank 201 and the droplet ejection head 300 up to the specified adjustment values ​​(step S204), and returns to the processing procedure of step S201.

[0103] The processor 215A performs the processing procedure of steps S205 to S206 based on the printing rate of the droplet ejection head 300, overlapping with the processing procedure of steps S203 to S204 based on the numerical values ​​related to the operation of the droplet ejection head 300.

[0104] That is, the processor 215A refers to the second pressure adjustment information 243A and identifies the adjustment values ​​for each of the supply pressure and recovery pressure corresponding to the acquired printing rate of the droplet ejection head 300 (step S205).

[0105] The processor 215A adjusts the supply pressure and recovery pressure of the liquid circulating between the tank 201 and the droplet ejection head 300 up to the specified adjustment values ​​(step S206), and returns to the processing procedure of step S201.

[0106] If the value acquired in step S201 is smaller than a predetermined threshold, the processor 215A can determine that no head pressure is being generated that would affect the circulation pressure of the liquid circulating through the droplet ejection head 300. In such a case, the processor 215A may stop adjusting the supply pressure and recovery pressure based on the values ​​related to the operation of the droplet ejection head 300 (the processing procedure of steps S203 to S204). In other words, if no head pressure is being generated that would affect the circulation pressure of the liquid circulating through the droplet ejection head 300, the processor 215A only adjusts the supply pressure and recovery pressure based on the printing rate of the droplet ejection head 300 (the processing procedure of steps S205 to S206). This makes it possible to maintain a constant circulation pressure (pressure) of the liquid inside the droplet ejection head 300 while suppressing an increase in the processing load.

[0107] 6 and 7, the droplet ejection system 1 may measure the flow rate of the liquid fed to the droplet ejection head 300 with a flow meter 212 connected to the first flow path RT1, and compare the measured flow rate of the liquid with the ejection amount calculated from the printing rate. The droplet ejection system 1 may adjust the supply pressure and the recovery pressure so as not to increase or to decrease the circulation pressure when the ejection amount calculated from the printing rate is greater than the flow rate of the liquid measured by the flow meter 212.

[0108] Specifically, when processor 215A identifies adjustment values ​​for each of the supply pressure and recovery pressure corresponding to the acquired printing rate of droplet ejection head 300 (step S205), it calculates the ejection volume estimated from the printing rate and also acquires the liquid flow rate measured by flow meter 212. Then, processor 215A compares the ejection volume calculated from the printing rate with the liquid flow rate measured by flow meter 212. If the ejection volume calculated from the printing rate is greater than the liquid flow rate measured by flow meter 212, processor 215A may control first proportional valve 204 and second proportional valve 205 so as not to increase the circulation pressure or to decrease the circulation pressure.

[0109] For example, in the droplet ejection head 300, air bubbles or foreign matter can cause droplet non-ejection in many channels (ejection holes 305h), resulting in a low ejection volume. In such cases, the circulation pressure may be increased based on information about the print rate, even though the actual ejection volume is low (see S205 and S206 in FIG. 15). Note that, as described in the explanation of FIG. 1, the print rate here refers to the ratio (S1 / S2) of the cumulative area S1 of the liquid ejected onto the target 50 to the area S2 of the spray surface 50SF of the target 50, for example, and can be calculated from the image data to be printed. This can result in an inappropriately high pressure inside the droplet ejection head 300, which can cause problems such as ink overflowing from the ejection holes 305h. To prevent such problems, it is recommended to calculate the expected ejection volume from the print rate, compare the expected ejection volume with the measurement value of the flow meter 212, and, if the expected ejection volume is greater than the measurement value of the flow meter 212, either not increase or decrease the circulation pressure.

[0110] Note that when there is no ejection, only circulation is performed, so it is normal for the ejection volume estimated from the printing rate to be smaller than the measurement value of flow meter 212. Also, during ejection, the measurement value of flow meter 212 is the sum of the ejection volume and the circulation flow rate, so it is normal for the ejection volume estimated from the printing rate to be smaller than the measurement value of flow meter 212. In contrast, a state in which the ejection volume calculated from the above-mentioned printing rate is larger than the flow rate measured by flow meter 212 is not normal.

[0111] As described above, a coating apparatus (e.g., droplet discharge system 1) according to an embodiment includes a storage unit (e.g., tank 201), a robot unit (e.g., robot arm 100), a first flow path (e.g., first flow path RT1), a second flow path (e.g., second flow path RT2), an acquisition unit (e.g., input / output interfaces 207, 207A), and a control unit (e.g., processors 215, 215A). The storage unit stores liquid to be supplied to a droplet discharge unit (e.g., droplet discharge head 300). The robot unit operates the droplet discharge unit. The first flow path connects the storage unit and the droplet discharge unit, and is a flow path for allowing the liquid stored in the storage unit to flow into the droplet discharge unit. The second flow path connects the storage unit and the droplet discharge unit, and is a flow path for returning the liquid that has flowed into the droplet discharge unit to the storage unit. The acquisition unit acquires information regarding the operation of the droplet discharge unit from a program (e.g., first control program 131) that controls the operation of the robot unit. The control unit controls the circulation pressure of the liquid circulating between the storage unit and the droplet discharge unit. The control unit controls the circulation pressure based on the information regarding the operation. As a result, according to the coating device of the embodiment, the circulation pressure of the liquid supplied to the droplet discharge unit can be maintained at an appropriate level even if it is affected by the operation of the liquid discharge unit by the robot unit.

[0112] The coating apparatus according to the embodiment may further include a first valve unit (e.g., first proportional valve 204), a second valve unit (e.g., second proportional valve 205), a first pressure measurement unit (e.g., third pressure sensor 210), and a second pressure measurement unit (e.g., fourth pressure sensor 211). The first valve unit may be inserted in the first flow path and control the flow rate of liquid supplied from the reservoir to the droplet discharge unit. The second valve unit may be inserted in the second flow path and control the flow rate of liquid supplied from the droplet discharge unit to the reservoir. The first pressure measurement unit may measure, as a supply pressure, the pressure of liquid flowing through the first flow path between the first valve unit and the droplet discharge unit. The second pressure measurement unit may measure, as a recovery pressure, the pressure of liquid flowing through the second flow path between the second valve unit and the droplet discharge unit. The acquisition unit may acquire a value related to the movement of the droplet discharge unit from a program that controls the operation of the robot unit. The control unit may control the first valve unit and the second valve unit to adjust the supply pressure and the recovery pressure based on the numerical value acquired by the acquisition unit. As a result, according to the coating device of the embodiment, the circulation pressure of the liquid supplied to the droplet discharge unit can be maintained at an appropriate level even if the circulation pressure is affected by the movement of the liquid discharge unit by the robot unit.

[0113] The acquisition unit may acquire the vertical position of the droplet ejection unit as a numerical value. The control unit may adjust the supply pressure and the recovery pressure so that the pressure of the liquid inside the droplet ejection unit, which changes depending on the position, remains constant. For example, the adjustment values ​​of each of the supply pressure and the recovery pressure may increase as the position becomes higher. As a result, according to the coating device of the embodiment, even if the liquid circulating through the droplet ejection unit is affected by the head pressure as the vertical position of the droplet ejection unit changes, the supply pressure and the recovery pressure of the liquid can be adjusted to cancel out the effect of the head pressure.

[0114] The acquisition unit may acquire the vertical acceleration acting on the droplet discharge unit as a numerical value. The control unit may adjust the supply pressure and the recovery pressure so that the pressure of the liquid inside the droplet discharge unit, which changes depending on the vertical acceleration, remains constant. For example, the adjustment values ​​of the supply pressure and the recovery pressure may decrease as the vertical upward acceleration increases. As a result, according to the coating device of the embodiment, even if the liquid circulating through the droplet discharge unit is affected by the head pressure as the vertical acceleration acting on the droplet discharge unit changes, the supply pressure and the recovery pressure of the liquid can be adjusted to cancel out the effect of the head pressure.

[0115] The acquisition unit may acquire the horizontal acceleration acting on the droplet discharge unit as a numerical value. The control unit may adjust the supply pressure and the recovery pressure so that the pressure of the liquid inside the droplet discharge unit, which changes depending on the horizontal acceleration, remains constant. For example, the adjustment value of the supply pressure may decrease as the acceleration of the liquid flowing inside the droplet discharge unit increases in a direction from downstream to upstream. Also, for example, the adjustment value of the recovery pressure may increase as the acceleration of the liquid flowing inside the droplet discharge unit increases in a direction from downstream to upstream. Thus, according to the coating device of the embodiment, even if the liquid circulating through the droplet discharge unit is affected by the hydraulic head pressure in response to a change in the horizontal acceleration acting on the droplet discharge unit, the supply pressure and the recovery pressure of the liquid can be adjusted to cancel out the effect of the hydraulic head pressure.

[0116] The coating apparatus according to the embodiment may further include a memory unit (e.g., storage 214). The memory unit may store pressure adjustment information (e.g., pressure adjustment information 242) that associates adjustment values ​​for the supply pressure and the recovery pressure for suppressing changes in the pressure of the liquid inside the droplet discharge unit with each magnitude of a numerical value. The control unit may refer to the pressure adjustment information and adjust the supply pressure and the recovery pressure to the adjustment values ​​that correspond to the numerical value acquired by the acquisition unit. As a result, according to the coating apparatus according to the embodiment, even if the liquid circulating through the droplet discharge unit is affected by the head pressure due to changes in various numerical values ​​related to the movement of the droplet discharge unit, the supply pressure and the recovery pressure of the liquid can be adjusted to cancel out the effect of the head pressure.

[0117] The acquisition unit (e.g., input / output interface 207A) may further acquire the printing rate of the droplet ejection unit from a program (e.g., second control program 132) that controls the operation related to the ejection of the droplet ejection unit. The control unit (e.g., processor 215A) may adjust the supply pressure and recovery pressure based on the numerical values ​​acquired by the acquisition unit, and may also adjust the supply pressure and recovery pressure based on the printing rate acquired by the acquisition unit. As a result, according to the coating device of the embodiment, the circulation pressure of the liquid supplied to the droplet ejection unit can be maintained at an appropriate level even if it is affected by the movement of the liquid ejection unit by the robot unit or the printing rate of the droplet ejection unit.

[0118] The control unit may adjust the supply pressure and the recovery pressure so that the pressure of the liquid inside the droplet ejection unit, which changes depending on the printing rate of the droplet ejection unit, remains constant. For example, the adjustment values ​​of the supply pressure and the recovery pressure may increase as the printing rate of the droplet ejection unit increases. As a result, the coating device according to the embodiment can adjust the supply pressure and the recovery pressure of the liquid to compensate for a shortage of liquid supply due to a change in the printing rate of the droplet ejection head.

[0119] The coating apparatus according to the embodiment may further include a storage unit (e.g., storage 214A). The storage unit may store first pressure adjustment information (e.g., first pressure adjustment information 242A) that associates adjustment values ​​of the supply pressure and the recovery pressure for suppressing changes in the pressure of the liquid inside the droplet discharge unit with each magnitude of a numerical value, and second pressure adjustment information (e.g., second pressure adjustment information 243A) that associates adjustment values ​​of the supply pressure and the recovery pressure for suppressing changes in the pressure of the liquid inside the droplet discharge unit with each magnitude of the printing rate of the droplet discharge unit. The control unit (e.g., processor 215A) may adjust the supply pressure and the recovery pressure to adjustment values ​​corresponding to the numerical value acquired by the acquisition unit, with reference to the first pressure adjustment information. At the same time, the control unit may adjust the supply pressure and the recovery pressure to adjustment values ​​corresponding to the printing rate acquired by the acquisition unit, with reference to the second pressure adjustment information. As a result, with the coating device according to the embodiment, it is possible to simultaneously adjust the supply pressure and recovery pressure based on various numerical values ​​related to the movement of the droplet ejection section and the supply pressure and recovery pressure based on the printing rate of the droplet ejection section.

[0120] The control unit may stop adjusting the supply pressure and the recovery pressure based on the numerical value when the numerical value acquired by the acquisition unit is smaller than a predetermined threshold value. As a result, the coating device according to the embodiment can maintain an appropriate circulation pressure while suppressing an increase in the processing load.

[0121] Further advantages and alternative embodiments may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0122] 1. Droplet ejection system 10 Foundations 50 Objects 50SF sprayed surface 100 Robot Arm 110 Arm section 120 Control Unit 121 Control device 122 Storage device 131 First Control Program 132 Second Control Program 200,200A circulation device 201 Tank 202 Discharge pump 203 Suction Pump 204 First proportional valve 205 Second proportional valve 206 Heater 207,207A Input / Output Interface 208 First pressure sensor 209 Second pressure sensor 210 Third pressure sensor 211 4th pressure sensor 212 Flow meter 214,214A Storage 215,215A processor 241 Pump Control Information 242 Pressure Regulation Information 242A First Pressure Adjustment Information 243A Secondary Pressure Adjustment Information 300 droplet ejection head 300SF discharge surface 301 Supply Reservoir 302 Supply Manifold 303 Recovery Manifold 304 Recovery Reservoir 305 elements 305h Discharge hole 310,320 Materials 321 Supply Inlet 322 Collection port RT1 First flow path RT2 Second flow path

Claims

1. A storage section for storing the liquid supplied to the droplet dispensing section, A first flow path connects the storage section and the droplet discharge section, and allows the liquid stored in the storage section to flow into the droplet discharge section. A second flow path connects the storage section and the droplet discharge section, and allows the liquid that has flowed into the droplet discharge section to be returned to the storage section. An acquisition unit that acquires numerical values ​​related to the movement of the droplet dispensing unit from a program that controls the operation of the droplet dispensing unit, A control unit that controls the circulation pressure of the liquid circulating between the storage unit and the droplet discharge unit, Equipped with, The control unit controls the circulating pressure based on the numerical values ​​related to the movement acquired by the acquisition unit in the painting apparatus.

2. The painting apparatus according to claim 1, wherein the numerical value relating to the movement of the droplet dispensing unit includes at least one of the vertical position of the droplet dispensing unit, the vertical acceleration acting on the droplet dispensing unit, and the horizontal acceleration acting on the droplet dispensing unit.

3. Further comprising a robot unit that performs the operation of the droplet dispensing unit, The painting apparatus according to claim 1, wherein the program is a program that controls the operation of the robot unit.

4. A first valve section is inserted into the first flow path and controls the flow rate of the liquid supplied from the storage section to the droplet discharge section, A second valve is inserted into the second flow path and controls the flow rate of the liquid supplied from the droplet discharge section to the storage section, A first pressure measuring unit measures the pressure of the liquid flowing between the first valve and the droplet discharge unit through the first flow path as the supply pressure, A second pressure measuring unit measures the pressure of the liquid flowing between the second valve and the droplet discharge unit through the second flow path as the recovery pressure, Furthermore, The painting apparatus according to any one of claims 1 to 3, wherein the control unit controls the first valve unit and the second valve unit based on the numerical values ​​obtained by the acquisition unit to adjust the supply pressure and the recovery pressure.

5. A storage section for storing the liquid supplied to the droplet dispensing section, A first flow path connects the storage section and the droplet discharge section, and allows the liquid stored in the storage section to flow into the droplet discharge section. A second flow path connects the storage section and the droplet discharge section, and allows the liquid that has flowed into the droplet discharge section to be returned to the storage section. A painting method in a painting apparatus equipped with, A process to obtain numerical values ​​related to the movement of the droplet dispensing unit from a program that controls the operation of the droplet dispensing unit, A process to control the circulation pressure of the liquid circulating between the storage unit and the droplet discharge unit based on the acquired numerical values ​​relating to the movement, Painting methods, including those mentioned above.

6. The painting method according to claim 5, wherein the numerical value relating to the movement of the droplet dispensing unit includes at least one of the vertical position of the droplet dispensing unit, the vertical acceleration acting on the droplet dispensing unit, and the horizontal acceleration acting on the droplet dispensing unit.

7. The robot unit that performs the operation of the droplet dispensing unit is further comprising The painting method according to claim 5, wherein the program is a program that controls the operation of the robot unit.

8. A first valve section inserted into the first flow path and controlling the flow rate of the liquid supplied from the storage section to the droplet discharge section, A second valve is inserted into the second flow path and controls the flow rate of the liquid supplied from the droplet discharge section to the storage section, A first pressure measuring unit measures the pressure of the liquid flowing between the first valve and the droplet discharge unit through the first flow path as the supply pressure, A second pressure measuring unit measures the pressure of the liquid flowing between the second valve and the droplet discharge unit through the second flow path as the recovery pressure, Furthermore, The painting method according to any one of claims 5 to 7, wherein the control process controls the first valve and the second valve based on the numerical values ​​obtained in the acquisition process to adjust the supply pressure and the recovery pressure.

Images