Coating device

Abstract

To provide a coating device that can accurately control a liquid coating position.SOLUTION: In a coating device 1A, a pulse power supply 21 applies a voltage between a nozzle 5 and an opposing electrode 18. A DC power supply 22 applies voltages to an electrode 112 and an electrode 122 of an annular electrode 10. A first annular electrode 11 and a second annular electrode 12 of the annular electrode 10 are arranged around a path P for a liquid droplet 90. A first rotary motor rotates the first annular electrode 11. The first annular electrode 11 rotates with a center of the first annular electrode 11 as a rotation center. A second rotary motor rotates the second annular electrode 12. The second annular electrode 12 rotates with a center of the second annular electrode 12 as a rotation center. When the liquid droplet 90 is discharged from the nozzle 5 to coat a medium 19A, the CPU rotates the first annular electrode 11 and the second annular electrode 12 and applies voltages to the first annular electrode 11 and the second annular electrode 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating device. [Background technology]

[0002] Inkjet printheads that apply ink using electrostatic force are known. The inkjet printhead described in Patent Document 1 includes an ink electrode and a correction electrode. The ink electrode is provided at the ink ejection port and connected to a signal source that applies voltage. When the signal source applies voltage, the ink becomes charged and flies from the ink ejection port. The correction electrode is cylindrical and provided downstream of the ink ejection port in the ink flight direction, and is connected to a DC power supply. When the ink passes through the correction electrode while voltage is applied from the DC power supply, the flight path of the ink is corrected by the Coulomb force between the ink and the correction electrode, allowing the ink to be accurately applied to the coating position.

[0003] In another embodiment of the inkjet recording head described in Patent Document 1, the correction electrode is cylindrical and has an axial length that varies depending on the circumferential position, and is rotatable. When ink passes through the correction electrode, it is deflected toward the cylindrical wall surface with the shortest axial length. Therefore, the inkjet recording head corrects the ink flight path by rotating the correction electrode before applying ink. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP-A-1-165447 Summary of the Invention [Problem to be solved by the invention]

[0005] In inkjet recording heads, due to manufacturing errors or other reasons, the correction electrodes may not be perfectly round when viewed from the direction of ink flight, but may be partially distorted. If the correction electrodes are partially distorted, the ink flight path may not be correctly corrected by the correction electrodes, resulting in a deviation in the ink application position. In the inkjet recording head, it is conceivable to reduce the effects of distortion of the correction electrodes by rotating the cylindrical correction electrodes when applying ink. However, in the inkjet recording head, the correction electrodes do not rotate when applying ink, so if the correction electrodes are partially distorted, the ink flight path may not be correctly corrected by the correction electrodes. Therefore, in the inkjet recording head, the ink application position may be incorrect.

[0006] An object of the present invention is to provide a coating device that can accurately control the position where a liquid is applied. [Means for solving the problem]

[0007] A coating device according to one aspect of the present invention comprises a nozzle, an opposing electrode facing the nozzle, a first power source that applies a voltage to the nozzle, a ring-shaped electrode arranged around a path through which liquid ejected from the nozzle passes, a second power source that applies a voltage to the ring-shaped electrode, a rotary drive unit that rotates the ring-shaped electrode, and a controller that controls the second power source and the rotary drive unit, wherein, when the liquid is ejected from the nozzle to coat a medium, the controller applies a voltage to the ring-shaped electrode using the second power source and rotates the ring-shaped electrode using the rotary drive unit around a central axis extending in the ejection direction of the liquid.

[0008] The coating device according to this aspect applies a voltage to an annular electrode arranged around the path, thereby drawing the liquid passing through the annular electrode toward the center of the annular electrode. The coating device applies a voltage to the annular electrode and rotates the annular electrode around a central axis extending in the discharge direction, so that even if a portion of the annular electrode is distorted, the liquid is drawn to the center of the annular electrode. Here, the coating device applies a voltage to the annular electrode and rotates the annular electrode when the liquid coats the medium. Therefore, the liquid is drawn to the center of the annular electrode as it passes through the annular electrode. This allows the coating device to accurately control the coating position of the liquid. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of a coating device 1A. [Figure 2] FIG. 2 is a plan view of the first annular electrode 11. [Figure 3] FIG. 10 is a diagram showing the coating device 1A when changing the path P. [Figure 4] FIG. 2 is a block diagram showing the electrical configuration of the coating device 1A. [Figure 5] 10 is a diagram showing the pulse voltage applied when dispensing the liquid 9, the rotation speeds of the first rotary motor 51 and the second rotary motor 54, and the DC voltage applied. [Figure 6] 10 is a flowchart of a main process. [Figure 7] FIG. 10 is a diagram showing the configuration of a coating device 1B of a modified example. [Figure 8] FIG. 10 is a plan view of a modified annular electrode 13. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described below with reference to the drawings. The drawings are used to explain technical features that can be adopted by the present invention. In other words, the configurations and the like shown in the drawings are merely illustrative examples and are not intended to limit the present invention.

[0011] <Configuration of coating device 1A> The configuration of the coating apparatus 1A will be described with reference to Fig. 1. Hereinafter, the left, right, front side of the page, rear side of the page, upper side, and lower side of Fig. 1 will be referred to as the left, right, front, rear, upper side, and lower side of the coating apparatus 1A, respectively. The left-right direction will also be referred to as the X-axis direction. The front-rear direction will also be referred to as the Y-axis direction. Note that in this embodiment, the up-down direction is used for convenience of explanation and is not limited to the vertical direction.

[0012] The coating device 1A shown in FIG. 1 coats a medium 19A with a liquid 9. In this embodiment, one of several types of liquid 9, including ink, is selected and used. When the liquid 9 is ink, the coating device 1A prints on the medium 19A as one mode of coating the medium 19A. The medium 19A is, for example, fabric, paper, or plastic film. The medium 19A may be conductive or insulating.

[0013] The coating device 1A has a discharge unit 2, a compressor 61, a regulator filter 62, a pressure gauge 63, a table 17, a counter electrode 18, a pulse power supply 21, an annular electrode 10, and a DC power supply 22. The discharge unit 2 has a housing 3, a nozzle 5, and a lid 7. The housing 3 is cylindrical with its axis in the vertical direction. The housing 3 is conductive. In Figures 1 to 3, 7, and 8, the conductive components are shown in black. The housing 3 has an opening 4 that opens upward. The housing 3 contains a liquid 9 in the opening 4.

[0014] The nozzle 5 is provided at the bottom end of the housing 3 and is cylindrical with its axis in the vertical direction. The nozzle 5 is conductive. The radial length of the nozzle 5 is shorter than the radial length of the housing 3. The axis of the nozzle 5 overlaps with the axis of the housing 3. Hereinafter, the axis common to the housing 3 and the nozzle 5 will be referred to as the central axis C. The nozzle 5 has an opening 6 that opens the nozzle 5 in the vertical direction and communicates with the opening 4. Hereinafter, the lower end of the opening 6 will be referred to as the outlet.

[0015] The lid 7 is provided at the upper end of the housing 3 and is disk-shaped with its axis in the vertical direction. The lid 7 is insulating. The radial length of the lid 7 is shorter than the radial length of the housing 3. The axis of the lid 7 overlaps with the central axis C. That is, in the discharge portion 2, the lid 7, housing 3, and nozzle 5 are aligned on the central axis C. The lid 7 is provided with a pair of openings (not shown) that open the lid 7 in the vertical direction and communicate with the opening 4. One end of a pipe 64 is fitted into one of the pair of openings, and one end of a pipe 65 is fitted into the other of the pair of openings. Air flows inside the pipes 64 and 65.

[0016] The other end of pipe 64 and the other end of pipe 65 are connected to compressor 61. A regulator filter 62 and a pressure gauge 63 are provided in pipes 64, 65 between compressor 61 and discharge section 2. Compressor 61 compresses the air, and regulator filter 62 adjusts the pressure at discharge section 2. Moisture and foreign matter may be mixed in with the air flowing inside pipes 64, 65. Regulator filter 62 removes moisture and foreign matter from the air. Pressure gauge 63 measures the pressure of the air flowing through pipes 64, 65.

[0017] The table 17 is provided below the nozzle 5 at a distance and is a plate-like structure that extends perpendicular to the vertical direction. The table 17 is insulating. The counter electrode 18 is provided on the upper surface of the table 17 and is a plate-like structure that extends perpendicular to the vertical direction. The counter electrode 18 is conductive. The counter electrode 18 supports the medium 19A from below. The counter electrode 18 and the nozzle 5 face each other in the vertical direction.

[0018] The pulsed power supply 21 applies a pulsed voltage of a predetermined period T1 (s) (see FIG. 5). The positive electrode of the pulsed power supply 21 is connected to the nozzle 5 of the discharge unit 2. The negative electrode of the pulsed power supply 21 is connected to the counter electrode 18 and a ground unit 29. The negative electrode of the pulsed power supply 21 is grounded by the ground unit 29. When the pulsed voltage is on, a potential difference of V1 (V) is generated between the nozzle 5 and the counter electrode 18. In this embodiment, the magnitude of the potential difference V1 is 1 to 10 (kV). When the pulsed voltage is off, no potential difference is generated between the nozzle 5 and the counter electrode 18 (0 (V), see FIG. 5).

[0019] When coating medium 19A, coating device 1A drives compressor 61 to create positive pressure inside discharge section 2. Liquid 9 is pushed downward from the discharge port of nozzle 5. Due to the balance between the force pushing out liquid 9 and the surface tension of liquid 9, droplets 90 of liquid 9 extend in a generally conical shape below nozzle 5. Coating device 1A turns on pulse voltage using pulse power supply 21. Liquid 9 is drawn downward from nozzle 5 toward counter electrode 18 due to Coulomb force.

[0020] The combined force of the pressure pushing out the liquid 9 and the Coulomb force pulling the liquid 9 out exceeds the surface tension of the liquid 9. Droplets 90 of the liquid 9 are pulled out of the nozzle 5 and ejected toward the counter electrode 18. The ejection direction D is downward. The droplets 90 are positively charged. The droplets 90 travel downward along a path P. The droplets 90 coat the medium 19A supported by the counter electrode 18. In this way, the coating device 1A coats the liquid 9 through the cooperation of the pressure applied by the compressor 61 and the voltage applied by the pulse power supply 21.

[0021] The annular electrode 10 is disposed below the nozzle 5 around a path P through which droplets 90 ejected from the nozzle 5 pass. The annular electrode 10 includes a first annular electrode 11 and a second annular electrode 12. The first annular electrode 11 and the second annular electrode 12 are aligned in the vertical direction. The second annular electrode 12 is disposed below the first annular electrode 11. The first annular electrode 11 and the second annular electrode 12 have the same structure. The following explanation will focus on the structure of the first annular electrode 11.

[0022] As shown in Fig. 2, the first annular electrode 11 has an insulating ring 111 and an electrode 112. The insulating ring 111 is disk-shaped with its axis in the vertical direction. The insulating ring 111 has insulating properties. The insulating ring 111 has an opening 113 that orients the insulating ring 111 in the vertical direction. The opening 113 has a circular shape centered on the axis of the insulating ring 111 in a plan view.

[0023] The electrode 112 is disk-shaped with its axis in the vertical direction. The electrode 112 is conductive. The diameter of the electrode 112 is approximately the same as the diameter of the opening 113. The electrode 112 fits into the opening 113. That is, the insulating ring 111 and the electrode 112 are arranged concentrically. The electrode 112 is provided with an opening 114 that orients the electrode 112 in the vertical direction. The opening 114 is circular in shape with the axis of the electrode 112 as its center in a plan view. The droplets 90 ejected from the nozzle 5 pass through the opening 114.

[0024] The second annular electrode 12 has an insulating ring 121 and an electrode 122. The insulating ring 121 has a configuration corresponding to the insulating ring 111, and the electrode 122 has a configuration corresponding to the electrode 112. Hereinafter, the center of the electrode 112 of the first annular electrode 11 will be referred to as the center of the first annular electrode 11, and the center of the electrode 122 of the second annular electrode 12 will be referred to as the center of the second annular electrode 12.

[0025] The first annular electrode 11 is rotatable around the center of the first annular electrode 11. The second annular electrode 12 is rotatable around the center of the second annular electrode 12. That is, the first annular electrode 11 and the second annular electrode 12 are rotatable around a central axis extending in the discharge direction D. In this embodiment, the first annular electrode 11 and the second annular electrode 12 rotate clockwise in a plan view. The first annular electrode 11 is rotated by driving a first rotary motor 51 (see Figure 4). The second annular electrode 12 is rotated around the center of the second annular electrode 12 by driving a second rotary motor 54 (see Figure 4).

[0026] The number of rotations per unit time of the first annular electrode 11 and the second annular electrode 12 is W1 ( / s) (see FIG. 5). The number of rotations W1 of the first annular electrode 11 and the second annular electrode 12 is greater than the frequency H1 ( / s) of the pulsed power supply 21. The frequency H1 is the reciprocal of the period T1 (H1=1 / T1). That is, the value (W1 / H1) obtained by dividing the number of rotations W1 of the first annular electrode 11 and the second annular electrode 12 by the frequency H1 of the pulsed power supply 21 is greater than 1.

[0027] The first annular electrode 11 is provided with a first movement mechanism 15 (see FIG. 4), not shown. The first movement mechanism 15 has a first X-axis motor 52 (see FIG. 4) and a first Y-axis motor 53 (see FIG. 4). The first X-axis motor 52 moves the first annular electrode 11 in the left-right direction. The first Y-axis motor 53 moves the first annular electrode 11 in the front-back direction. In other words, the first movement mechanism 15 can move the first annular electrode 11 radially relative to an axis extending in the discharge direction D.

[0028] The second annular electrode 12 is provided with a second movement mechanism 16 (not shown). The second movement mechanism 16 has a second X-axis motor 55 (see FIG. 4) and a second Y-axis motor 56 (see FIG. 4). The second X-axis motor 55 moves the second annular electrode 12 in the left-right direction. The second Y-axis motor 56 moves the second annular electrode 12 in the front-back direction. In other words, the second annular electrode 12 can be moved by the second movement mechanism 16 in the radial direction relative to an axis extending in the discharge direction D.

[0029] The DC power supply 22 applies a DC voltage (see FIG. 5). As shown in FIG. 1, the positive electrode of the pulse power supply 21 is connected to the electrode 112 and the electrode 122. The negative electrode of the DC power supply 22 is connected to the earth part 28 and is grounded by the earth part 28. The polarity of the voltage that the DC power supply 22 applies to the electrode 112 and the electrode 122 is the same as the polarity of the voltage that the pulse power supply 21 applies to the discharge part 2. The DC power supply 22 applies a voltage V2 (V) to the electrode 112 and the electrode 122. In this embodiment, the magnitude of the potential difference V2 is 1 to 10 (kV). The magnitude of the potential difference V2 may be larger or smaller than the magnitude of the potential difference V1, or may be the same as the magnitude of the potential difference V1.

[0030] As shown in Fig. 2, the first annular electrode 11 is rotated by a first rotary motor 51 and has a voltage applied thereto by a DC power supply 22. A path P of a droplet 90 may deviate from a central axis C due to an external disturbance. Fig. 2 shows a case where the path P deviates to the right from the central axis C. When the droplet 90 passes through the first annular electrode 11, it is subjected to a Coulomb force by the electrode 112. Both the droplet 90 and the electrode 112 are positively charged.

[0031] The droplet 90 is subjected to a rightward Coulomb force from the left part of the electrode 112. The droplet 90 is subjected to a leftward Coulomb force from the right part of the electrode 112. Because the droplet 90 is located to the right of the center of the first annular electrode 11, the Coulomb force it receives from the right part of the electrode 112 is greater than the Coulomb force it receives from the left part of the electrode 112. The droplet 90 is subjected to a rearward Coulomb force from the front part of the electrode 112. The droplet 90 is subjected to a forward Coulomb force from the rear part of the electrode 112. Because the droplet 90 is located at the same position as the center of the first annular electrode 11 in the front-to-rear direction, the Coulomb force it receives from the rear part of the electrode 112 is the same magnitude as the Coulomb force it receives from the rear part of the electrode 112. In other words, the droplet 90 is attracted toward the center of the first annular electrode 11 by the resultant force of the Coulomb forces it receives from the electrode 112. In this way, as the first annular electrode 11 rotates and a voltage is applied to the first annular electrode 11, the first annular electrode 11 corrects the path P of the droplet 90. The second annular electrode 12 also corrects the path P of the droplet 90 in a similar manner.

[0032] Furthermore, before coating the medium 19A, the coating device 1A moves the first annular electrode 11 in the front-to-back and left-to-right directions using the first X-axis motor 52 and the first Y-axis motor 53. Similarly, before coating the medium 19A, the coating device 1A moves the second annular electrode 12 in the front-to-back and left-to-right directions using the second X-axis motor 55 and the second Y-axis motor 56. When the droplets 90 pass through the first annular electrode 11, they are attracted to the center of the first annular electrode 11, and when they pass through the second annular electrode 12, they are attracted to the center of the second annular electrode 12. As a result, the path P is deflected from the central axis C, and the coating device 1A coats the droplets 90 at any position on the medium 19A.

[0033] <Electrical configuration of coating device 1A> The electrical configuration of the coating device 1A will be described with reference to Figure 4. The coating device 1A has a CPU 31, a ROM 32, a RAM 33, a storage device 34, drive circuits 41 to 47, power supply circuits 48 and 49, an input unit 35, and an output unit 36. The CPU 31 controls the coating device 1A. The ROM 32 stores various setting information. The RAM 33 temporarily stores various information. The storage device 34 is non-volatile and stores a control program for executing the main processing (see Figure 6) described below.

[0034] The CPU 31 inputs and outputs various signals to and from the ROM 32, RAM 33, storage device 34, drive circuits 41 to 47, power supply circuits 48 and 49, input unit 35, and output unit 36. The input unit 35 accepts input of various information, instructions, etc. from the user and outputs them to the CPU 31. The input unit 35 is, for example, a keyboard that accepts input in response to user operations. The output unit 36 ​​outputs various information based on instructions from the CPU 31. The output unit 36 ​​is, for example, a liquid crystal display that displays a screen showing various information.

[0035] The drive circuit 41 is connected to the first rotary motor 51. The drive circuit 42 is connected to the first X-axis motor 52. The drive circuit 43 is connected to the first Y-axis motor 53. The drive circuit 44 is connected to the second rotary motor 54. The drive circuit 45 is connected to the second X-axis motor 55. The drive circuit 46 is connected to the second Y-axis motor 56. The drive circuit 47 is connected to the compressor 61. The first rotary motor 51, the first X-axis motor 52, the first Y-axis motor 53, the second rotary motor 54, the second X-axis motor 55, and the second Y-axis motor 56 are, for example, stepping motors. The drive circuits 41, 42, 43, 44, 45, 46, and 47 control the drive of the first rotary motor 51, the first X-axis motor 52, the first Y-axis motor 53, the second rotary motor 54, the second X-axis motor 55, the second Y-axis motor 56, and the compressor 61 in accordance with instructions input from the CPU 31.

[0036] The power supply circuit 48 is connected to the pulse power supply 21. The power supply circuit 49 is connected to the DC power supply 22. The power supply circuits 48 and 49 control the voltages applied by the pulse power supply 21 and the DC power supply 22 in response to instructions input from the CPU 31.

[0037] <Main processing> The main processing executed by the CPU 31 will be described with reference to Figure 6. In the main processing, the medium 19A is coated with the liquid 9. The user inputs an instruction to execute the main processing via the input unit 35. The CPU 31 reads out an initial processing program from the storage device 34. This causes the CPU 31 to start the main processing. Before the main processing starts, the center of the first annular electrode 11 and the center of the second annular electrode 12 coincide with the central axis C.

[0038] When the main processing starts, the CPU 31 determines whether or not to deflect the path P of the droplet 90 (S1). When deflecting the path P of the droplet 90, the user inputs an instruction to deflect the path P via the input unit 35. When the CPU 31 does not receive the instruction to deflect, it determines not to deflect the path P (S1: NO) and proceeds to S3.

[0039] When the CPU 31 receives the deflection command, it determines that the path P is to be deflected (S1: YES), and moves the first annular electrode 11 and the second annular electrode 12 (S2). In the processing of S2, the CPU 31 drives the first X-axis motor 52 and the first Y-axis motor 53 to move the first annular electrode 11, and drives the second X-axis motor 55 and the second Y-axis motor 56 to move the second annular electrode 12. The CPU 31 then moves the processing to S3.

[0040] The CPU 31 determines whether or not to start coating the medium 19A (S3). When starting coating the medium 19A, the user inputs a coating start command via the input unit 35. If the CPU 31 does not receive a coating start command, it determines not to start coating (S3: NO) and returns the process to S3.

[0041] When the CPU 31 receives the coating start command, it determines to start coating (S3: YES), and drives the first rotary motor 51 to rotate the first annular electrode 11, and drives the second rotary motor 54 to rotate the second annular electrode 12 (S4). The CPU 31 then applies a DC voltage to the first annular electrode 11 and the second annular electrode 12 using the DC power supply 22 (S5). The rotation of the first annular electrode 11 and the second annular electrode 12 and the application of the DC voltage to the first annular electrode 11 and the second annular electrode 12 begin t1 (s) after the coating start command is received at 0 (s) (see FIG. 5).

[0042] The CPU 31 drives the compressor 61 to make the pressure inside the discharge section 2 positive (S6). The CPU 31 starts applying a pulse voltage using the pulse power supply 21 (S7). Coating of the liquid 9 onto the medium 19A begins. The application of the pulse voltage begins t2 (s) after the coating start instruction is received at 0 (s) (see FIG. 5). Note that t2 is greater than t1 (t2>t1). The CPU 31 proceeds to S8.

[0043] The CPU 31 determines whether or not application of the liquid 9 to the medium 19A has been completed (S8). If the CPU 31 determines that application of the liquid 9 has not been completed (S8: NO), the process returns to S7. If the CPU 31 determines that application of the liquid 9 has been completed (S8: YES), the CPU 31 stops application of the pulse voltage by the pulse power supply 21 (S9). In this embodiment, application of the pulse voltage is stopped t3 (s) after receiving the application start command at 0 (s) (see FIG. 5). Note that t3 is greater than t2 (t3>t2). The CPU 31 stops driving the compressor 61 and returns the pressure in the discharge unit 2 to atmospheric pressure (S10).

[0044] The CPU 31 stops the application of DC voltage to the first annular electrode 11 and the second annular electrode 12 by the DC power supply 22 (S11). The CPU 31 stops the rotation of the first annular electrode 11 driven by the first rotary motor 51, and stops the rotation of the second annular electrode 12 driven by the second rotary motor 54 (S12). The rotation of the first annular electrode 11 and the second annular electrode 12 and the application of DC voltage to the first annular electrode 11 and the second annular electrode 12 are stopped t4 (s) after the coating start command is received at 0 (s) (see FIG. 5). Note that t4 is greater than t3 (t4>t3). The CPU 31 ends the main processing.

[0045] <Actions and Effects of This Embodiment> As described above, the pulse power supply 21 applies a voltage between the nozzle 5 and the counter electrode 18. The DC power supply 22 applies a voltage to the electrode 112 and the electrode 122 of the annular electrode 10. The first annular electrode 11 and the second annular electrode 12 of the annular electrode 10 are arranged around the path P of the droplets 90. The first rotary motor 51 rotates the first annular electrode 11. The first annular electrode 11 rotates around the center of the first annular electrode 11. The second rotary motor 54 rotates the second annular electrode 12. The second annular electrode 12 rotates around the center of the second annular electrode 12. When the droplets 90 are discharged from the nozzle 5 to coat the medium 19A, the CPU 31 rotates the first annular electrode 11 and the second annular electrode 12 (S4) and applies a voltage to the first annular electrode 11 and the second annular electrode 12 (S5). According to this, the coating device 1A applies a voltage to the annular electrode 10 arranged around the path P of the droplets 90, thereby attracting the droplets 90 passing through the annular electrode 10 toward the center of the annular electrode 10. The coating device 1A applies a voltage to the annular electrode 10 and rotates the annular electrode 10 around a central axis extending in the discharge direction D. As a result, even if a portion of the electrode 112 or the electrode 122 is distorted, the droplets 90 are attracted to the center of the annular electrode 10. Here, the coating device 1A applies a voltage to the annular electrode 10 and rotates the annular electrode 10 when the droplets 90 coat the medium 19A. Therefore, as the droplets 90 pass through the annular electrode 10, they are attracted to the center of the annular electrode 10. Therefore, the coating device 1A can accurately control the coating position of the droplets 90.

[0046] In the coating apparatus 1A, the CPU 31 starts the rotation of the first annular electrode 11 and the second annular electrode 12 (S4) and starts the application of voltage to the first annular electrode 11 and the second annular electrode 12 (S5) before starting the application of voltage by the pulse power supply 21 (S7). After stopping the application of voltage by the pulse power supply 21 (S9), the CPU 31 stops the application of voltage to the first annular electrode 11 and the second annular electrode 12 (S11) and stops the rotation of the first annular electrode 11 and the second annular electrode 12 (S12). That is, when the pulse power supply 21 applies a voltage, the CPU 31 rotates the annular electrode 10 and applies a voltage to the annular electrode 10. In the coating apparatus 1A, droplets 90 are ejected from the nozzle 5 when the pulse power supply 21 applies a voltage. When the pulse power supply 21 applies a voltage, the coating device 1A applies a voltage to the annular electrode 10 and rotates the annular electrode 10, which makes it easier to attract the droplets 90 passing through the annular electrode 10 to the center of the annular electrode 10. Therefore, the coating device 1A can more accurately control the coating position of the droplets 90.

[0047] In the coating apparatus 1A, the pulse power supply 21 applies a pulse voltage with a period T1. The CPU 31 rotates the annular electrode 10 and applies a voltage to the annular electrode 10 over the pulse voltage period T1, which is the time from when the pulse voltage is turned on by the pulse power supply 21 until the next time the pulse voltage is turned on (see FIG. 5). In the coating apparatus 1A, droplets 90 are ejected when the pulse voltage is on, and the ejection of droplets 90 is stopped when the pulse voltage is off. In the coating apparatus 1A, the annular electrode 10 is rotated over the pulse voltage period T1, which includes both the time when the pulse voltage is on and the time when the pulse voltage is off. Therefore, the coating apparatus 1A is able to more easily attract droplets 90 passing through the annular electrode 10 toward the center of the annular electrode 10, thereby enabling more accurate control of the coating position of the droplets 90.

[0048] In the coating device 1A, the number of rotations per unit time W1 of the first annular electrode 11 and the second annular electrode 12 is greater than the frequency H1 of the pulsed power supply 21. In the coating device 1A, droplets 90 are ejected when the pulsed voltage is on. In the coating device 1A, the annular electrode 10 rotates one or more times while the pulsed voltage ejects one droplet 90, so that the droplets 90 passing through the annular electrode 10 are more likely to be attracted to the center of the annular electrode 10. Therefore, the coating device 1A can more accurately control the coating position of the droplets 90.

[0049] In the coating device 1A, the annular electrode 10 includes a first annular electrode 11 and a second annular electrode 12. The first annular electrode 11 and the second annular electrode 12 are aligned in the vertical direction. The second annular electrode 12 is disposed downstream of the first annular electrode 11 along the path P. As a result, in the coating device 1A, the second annular electrode 12 attracts the droplets 90 that have passed through the first annular electrode 11 toward the center of the second annular electrode 12. Therefore, the coating device 1A can more accurately control the coating position of the droplets 90 compared to when the annular electrode 10 is configured from a single annular electrode.

[0050] The coating device 1A has a first movement mechanism 15 and a second movement mechanism 16. A first X-axis motor 52 and a first Y-axis motor 53 of the first movement mechanism 15 move the first annular electrode 11 in a radial direction relative to an axis extending in the discharge direction D. A second X-axis motor 55 and a second Y-axis motor 56 of the second movement mechanism 16 move the second annular electrode 12 in a radial direction relative to an axis extending in the discharge direction D. As a result, droplets 90 passing through the annular electrode 10 are attracted to the center of the annular electrode 10, and therefore, by moving the annular electrode 10, the coating device 1A can coat the droplets 90 at any position on the medium 19A.

[0051] In the coating device 1A, the polarity of the voltage applied by the DC power supply 22 to the electrodes 112 and 122 is the same as the polarity of the voltage applied by the pulse power supply 21 to the discharge unit 2. As a result, the annular electrode 10 is charged with the same polarity as the charge on the droplets 90. The droplets 90 are attracted to the center of the annular electrode 10 by Coulomb force (see FIG. 2). Here, since the Coulomb force is inversely proportional to the square of the distance from the annular electrode 10 to the droplets 90, the droplets 90 are attracted more to the center of the annular electrode 10 as they pass a position on the annular electrode 10 closer to the electrode 112 or electrode 122. Therefore, the coating device 1A can more accurately control the coating position of the droplets 90.

[0052] In the coating device 1A, the type of liquid 9 includes ink. When the liquid 9 is ink, the coating device 1A prints on the medium 19A as one mode of coating the medium 19A. This allows the coating device 1A to more accurately control the printing position of droplets 90 when printing on the medium 19A.

[0053] <Modification> The present invention can be modified in various ways from the above-described embodiment. The various modifications described below can be combined with each other as long as no contradiction occurs.

[0054] A modified coating apparatus 1B will be described with reference to Fig. 7. The following mainly describes the differences between coating apparatus 1B and coating apparatus 1A. In coating apparatus 1B, components having the same shape or function as those in the above embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

[0055] In coating device 1B, medium 19B is coated instead of medium 19A. Medium 19B is conductive. The negative pole of pulse power supply 21 is connected to medium 19B. Coating device 1A does not have a counter electrode 18, and table 17 supports medium 19B. Pulse power supply 21 applies a pulse voltage between discharge portion 2 and medium 19B. In this way, any configuration is possible as long as voltage is applied between nozzle 5. The wiring on the negative pole side of pulse power supply 21 may be changed as appropriate. In this case, medium 19B is an example of the "counter electrode" of the present invention.

[0056] In the coating device 1B, the annular electrodes 10 include only the first annular electrode 11. As described above, the number of the annular electrodes 10 is not limited to two, and may be one, or three or more.

[0057] Referring to FIG. 8 , modified shapes of the annular electrode 10 will be described. In the above embodiment, the annular electrode 10 is circular. However, the shape of the annular electrode 10 is not limited as long as it is arranged in a circular shape around the path P, and may be modified as appropriate. The annular electrode 10 includes an annular electrode 13 having a shape different from the first annular electrode 11 and the second annular electrode 12. The annular electrode 13 has insulating plates 131 and electrodes 132. The insulating plates 131 are four plates arranged in a circular shape with the vertical axis as the axis. The insulating plates 131 are insulating. The electrodes 132 are four plates arranged in a circular shape with the vertical axis as the axis as well. One electrode 132 is provided inside one insulating plate 131. The electrodes 132 are conductive. Unlike the annular electrode 13, the electrode 132 may not be a single plate connected in a circular shape, but may be multiple plates arranged in a circular shape. The annular electrode 10 is not limited to a circular shape and may be, for example, a polygonal shape. The annular electrode 10 is not limited to a disk shape, but may be, for example, a cylindrical shape having a thickness in the vertical direction.

[0058] Other modifications will be described. In the above embodiment, the liquid 9 is ejected downward, but the ejection direction D is not limited to downward. In this case, the annular electrode 10 may be rotatable about a central axis extending in the ejection direction D. The central axis of the annular electrode 10 may include a directional component of the ejection direction D and may be inclined with respect to the ejection direction D. In the above embodiment, the annular electrode 10 rotates clockwise in a plan view, but it may also rotate counterclockwise in a plan view. The first annular electrode 11 and the second annular electrode 12 may rotate in different directions. For example, when the first annular electrode 11 rotates clockwise in a plan view, the second annular electrode 12 may rotate counterclockwise in a plan view. When the first annular electrode 11 rotates counterclockwise in a plan view, the second annular electrode 12 may rotate clockwise in a plan view. The first annular electrode 11 may not have an insulating ring 111. The second annular electrode 12 may not have an insulating ring 121.

[0059] In the above embodiment, the annular electrode 10 is not limited to being applied with a voltage from the DC power supply 22. The annular electrode 10 may be applied with a voltage from a pulse power supply that applies a pulse voltage, an AC power supply that applies a sinusoidal AC voltage, or the like, instead of the DC power supply 22. In this case, the coating device 1A may have a circuit that converts the voltage output from the pulse power supply or the AC power supply into a DC voltage.

[0060] The coating device 1A is not limited to applying a voltage between the nozzle 5 and the counter electrode 18 using the pulse power supply 21. The coating device 1A may apply a voltage between the nozzle 5 and the counter electrode 18 using a DC power supply that applies a DC voltage, an AC power supply that applies a sinusoidal AC voltage, or the like, instead of the pulse power supply 21. In this case, the coating device 1A may have a circuit that converts the voltage output from the DC power supply or the AC power supply into a pulse voltage.

[0061] In the above embodiment, the rotation speed W1 of the first annular electrode 11 and the second annular electrode 12 per unit time is greater than the frequency H1 of the pulsed power supply 21. The rotation speed W1 of the first annular electrode 11 and the second annular electrode 12 per unit time may be the same as the frequency H1 of the pulsed power supply 21. The value (W1 / H1) obtained by dividing the rotation speed W1 of the first annular electrode 11 and the second annular electrode 12 by the frequency H1 of the pulsed power supply 21 is 1. In this case, too, the annular electrode 10 rotates once while a droplet 90 is ejected once by the pulsed voltage, so that the droplet 90 passing through the annular electrode 10 is easily attracted to the center of the annular electrode 10. The rotation speed W1 of the first annular electrode 11 per unit time may be smaller than the frequency H1 of the pulsed power supply 21. The rotation speed W1 of the second annular electrode 12 per unit time may be smaller than the frequency H1 of the pulsed power supply 21.

[0062] The coating device 1A may not include the first movement mechanism 15. The first movement mechanism 15 may not include the first X-axis motor 52. The first movement mechanism 15 may not include the first Y-axis motor 53. The first movement mechanism 15 may include a first Z-axis motor that moves the first annular electrode 11 in the vertical direction. The coating device 1A may not include the second movement mechanism 16. The second movement mechanism 16 may not include the second X-axis motor 55. The second movement mechanism 16 may not include the second Y-axis motor 56. The second movement mechanism 16 may include a second Z-axis motor that moves the second annular electrode 12 in the vertical direction.

[0063] The polarity of the voltage applied by the DC power supply 22 to the electrodes 112 and 122 may be opposite to the polarity of the voltage applied by the pulse power supply 21 to the discharge unit 2. In this case, the annular electrode 10 is charged with a polarity opposite to the charge on the droplets 90. In this case, the droplets 90 are also attracted to the center of the annular electrode 10 by Coulomb force.

[0064] The type of liquid 9 may be changed as appropriate. The type of liquid 9 does not have to include ink. When the liquid 9 is ink, the ink may be water-soluble or oil-based. The ink may be UV ink that hardens when irradiated with ultraviolet light.

[0065] The coating device 1A may use, for example, a microcomputer, an ASIC (Application Specific Integrated Circuits), an FPGA (Field Programmable Gate Array), etc. for control instead of the CPU 31. The main processing may be distributed using a plurality of CPUs 31, or may be performed by combining the CPU 31 with an ASIC, etc.

[0066] Non-transitory storage media such as ROM 32 and storage device 34 may be any storage media capable of retaining information regardless of the period for which the information is stored. Non-transitory storage media do not have to include temporary storage media (e.g., transmitted signals). The program for executing the main processing may be downloaded (i.e., transmitted as a transmission signal) from a server connected to the network and stored in storage device 34 or the like. In this case, the program or the like may be stored in a non-transitory storage medium such as an HDD provided in the server.

[0067] <Other> The pulse power supply 21 is an example of a "first power supply" of the present invention. The DC power supply 22 is an example of a "second power supply" of the present invention. The first rotary motor 51 and the second rotary motor 54 are an example of a "rotation drive unit" of the present invention. The CPU 31 is an example of a "controller" of the present invention. The front-rear direction and the left-right direction are examples of a "radial direction" of the present invention. The first moving mechanism 15 and the second moving mechanism 16 are examples of an "electrode moving unit" of the present invention. [Explanation of symbols]

[0068] 1 Coating device 5 nozzles 9 liquid 10 Ring electrode 11 First annular electrode 12 Second annular electrode 15 1st movement mechanism 16 Second movement mechanism 21 Pulse power supply 22 DC power supply 31 CPU 51 First rotating motor 54 Second rotating motor

Claims

1. A nozzle; a counter electrode facing the nozzle; a first power source that applies a voltage to the nozzle; an annular electrode disposed around a path through which the liquid ejected from the nozzle passes; a second power source that applies a voltage to the annular electrode; a rotation drive unit that rotates the annular electrode; a controller that controls the second power source and the rotation drive unit, and that applies a voltage to the annular electrode using the second power source and rotates the annular electrode around a central axis extending in the ejection direction of the liquid using the rotation drive unit when the liquid is ejected from the nozzle to coat the medium. A coating device characterized by:

2. 2. The coating device according to claim 1, wherein the controller, when the first power source applies a voltage, causes the second power source to apply a voltage to the annular electrode and causes the rotation drive unit to rotate the annular electrode.

3. the first power supply applies a pulse voltage at a predetermined cycle; The controller causes the second power source to apply a voltage to the annular electrode over the period in which the first power source applies the pulse voltage, and causes the rotation drive unit to rotate the annular electrode. The coating device according to claim 2,

4. the first power source applies a pulse voltage at a predetermined frequency per unit time; the controller rotates the annular electrode so that the number of rotations of the annular electrode per unit time is equal to or greater than the frequency. The coating device according to claim 1 ,

5. The coating device according to claim 1 , wherein the annular electrodes include a first annular electrode and a second annular electrode provided downstream of the first annular electrode in the path.

6. The coating device according to claim 1 , further comprising an electrode moving unit that moves the annular electrode in a radial direction of the central axis.

7. 2. The coating device according to claim 1, wherein the second power source applies a voltage having the same polarity as a voltage applied by the first power source.

8. 2. The coating device according to claim 1, wherein the liquid is ink for printing on the medium.

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