Liquid discharge device and control method for liquid discharge device

Abstract

To provide a liquid discharge device capable of appropriately removing foreign substances from a medium and a control method for the liquid discharge device.SOLUTION: A liquid discharge device comprises: a discharge unit 21 which discharges liquid while reciprocating in a first direction D1 and a second direction D2 relative to a medium 99 transported in a transport region A1; a recovery unit which is positioned in the first direction relative to the transport region; and a control unit 43. The discharge unit includes: a head 22 which has a nozzle surface 24 on which nozzles 23 for discharging liquid are opened; and a removal electrode which is positioned in the first direction relative to the head and is applied with voltage. The control unit switches the polarity of the voltage applied to the removal electrode between a case where the removal electrode is opposed to the medium and a case where the removal electrode is opposed to the recovery unit when the discharge unit moves in the first direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 describes a liquid ejection device that includes a head that ejects liquid onto a medium, and a removal mechanism that removes foreign matter such as paper powder and dust from the medium by blowing air onto the medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-118095 A Summary of the Invention [Problem to be solved by the invention]

[0004] In such a liquid ejection device, there is a risk that foreign matter may be stirred up from the medium by blowing air onto the medium, and in this case, the stirred up foreign matter may adhere to the head. [Means for solving the problem]

[0005] A liquid ejection device that solves the above problem comprises an ejection section that ejects liquid while moving back and forth in a first direction and a second direction relative to a medium transported through a transport region, a recovery section that is positioned in the first direction relative to the transport region, and a control section, wherein the ejection section has a head having a nozzle face through which nozzles that eject liquid open, and a removal electrode that is positioned in the first direction relative to the head and to which a voltage is applied, and when the ejection section moves in the first direction, the control section switches the polarity of the voltage applied to the removal electrode between when the removal electrode faces the medium and when it faces the recovery section.

[0006] A control method for a liquid ejection device that solves the above problem includes an ejection section that ejects liquid while moving back and forth in a first direction and a second direction relative to a medium transported through a transport region, and a recovery section located in the first direction relative to the transport region, wherein the ejection section has a head having a nozzle face through which nozzles that eject liquid open, and a removal electrode that is located in the first direction relative to the head and to which a voltage is applied, and includes switching the polarity of the voltage applied to the removal electrode when the removal electrode faces the medium and when it faces the recovery section when the ejection section moves in the first direction. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing an embodiment of a liquid ejection device. [Diagram 2] FIG. 2 is a front view showing the inside of the liquid ejection device. [Diagram 3] FIG. 3 is a front view showing the first removal electrode when removing foreign matter. [Figure 4] FIG. 4 is a front view of the first collection section when it collects foreign matter. [Diagram 5] FIG. 5 is a front view showing the second removal electrode removing the foreign matter. [Figure 6] FIG. 6 is a front view of the second collection section when it collects foreign matter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of a liquid ejection device will be described below with reference to the drawings. The liquid ejection device is, for example, an inkjet printer that prints images such as characters and photographs by ejecting ink, which is an example of a liquid, onto a medium such as paper or fabric. More specifically, the liquid ejection device is a serial printer.

[0009] <Liquid discharge device> As shown in FIG. 1, the liquid ejection device 11 includes a housing 12. A supply port 13 and a discharge port 14 are opened in the housing 12. A medium 99 is supplied into the housing 12 through the supply port 13. More specifically, the medium 99 before printing is supplied from the supply port 13. In one example, the supply port 13 opens at the rear surface of the housing 12. The medium 99 is discharged from inside the housing 12 through the discharge port 14. More specifically, the printed medium 99 is discharged from the discharge port 14. In one example, the discharge port 14 opens at the front surface of the housing 12.

[0010] The liquid ejection device 11 may include a supply tray 15. One or more media 99 are loaded on the supply tray 15. The supply tray 15 extends from the supply port 13. In one example, the supply tray 15 extends obliquely upward from within the housing 12. Therefore, the media 99 tend to slide down on the supply tray 15 into the housing 12. The supply tray 15 may be configured to be able to be housed within the housing 12.

[0011] The liquid ejection device 11 may include a discharge tray 16. The discharge tray 16 is a tray that receives the medium 99 discharged from the discharge port 14. The discharge tray 16 extends from the discharge port 14. The discharge tray 16 may be configured to be able to be housed in the housing 12.

[0012] The liquid ejection device 11 may include an opening / closing body 17. The opening / closing body 17 is attached to the housing 12. The opening / closing body 17 opens and closes with respect to the housing 12. The opening / closing body 17 shown in FIG. 1 is closed with respect to the housing 12. The opening / closing body 17 is located at the top of the housing 12. The opening / closing body 17 is, for example, a cover. The opening / closing body 17 may be, for example, a scanner that reads an image. When the opening / closing body 17 is opened, the inside of the housing 12 is exposed. In detail, when the opening / closing body 17 is opened, a discharge unit 21, which will be described later, is exposed. A user can access the discharge unit 21 by opening the opening / closing body 17. A user can perform maintenance on the discharge unit 21 by accessing the discharge unit 21.

[0013] The liquid ejection device 11 may include an operation panel 18. The operation panel 18 is a panel for operating the liquid ejection device 11. The operation panel 18 is attached to the housing 12, for example. In one example, the operation panel 18 is located on the front side of the housing 12. The operation panel 18 may have buttons, switches, levers, a display, and the like. A user operates the liquid ejection device 11 through the operation panel 18.

[0014] As shown in FIG. 2, the medium 99 is transported in a transport direction Y1 within the housing 12. The transport direction Y1 is a direction from the rear surface of the housing 12 toward the front surface of the housing 12. The medium 99 is transported in the transport direction Y1 through a transport area A1 within the housing 12. The transport area A1 is an area within the housing 12 through which the medium 99 passes. More specifically, the transport area A1 indicates an area through which the medium 99 passes when the liquid ejection device 11 is viewed from the front. In one example, the transport area A1 is an area in which a support portion 31, which will be described later, is located.

[0015] The liquid ejection device 11 includes an ejection unit 21. The ejection unit 21 is housed in a housing 12. The ejection unit 21 is configured to eject liquid onto a medium 99. The ejection unit 21 prints an image on the medium 99 by ejecting the liquid onto the medium 99.

[0016] The ejection unit 21 ejects liquid onto the medium 99 being transported through the transport region A1. The ejection unit 21 ejects liquid while moving back and forth in a first direction D1 and a second direction D2 relative to the medium 99. The first direction D1 is a direction different from the transport direction Y1. The second direction D2 is a direction opposite to the first direction D1. The ejection unit 21 scans the medium 99 by moving back and forth in the first direction D1 and the second direction D2. The ejection unit 21 traverses the transport region A1 by moving in the first direction D1 and the second direction D2. At this time, the ejection unit 21 moves between the transport region A1 and outside the transport region A1.

[0017] The ejection unit 21 has a head 22. The head 22 has a nozzle surface 24 in which one or more nozzles 23 are opened. The nozzle surface 24 faces a medium 99. The head 22 ejects liquid from the nozzles 23.

[0018] The ejection unit 21 has a carriage 25. The carriage 25 carries the head 22. The carriage 25 is configured to move in a first direction D1 and a second direction D2. The movement of the carriage 25 causes the head 22 to move.

[0019] When the discharge unit 21 moves back and forth over the medium 99, it moves on an outward path and a return path. When the discharge unit 21 moves back and forth over the medium 99, it moves in a first direction D1 and then moves in a second direction D2. Therefore, the discharge unit 21 moves in the first direction D1 on the outward path. The discharge unit 21 moves in the second direction D2 on the return path.

[0020] The ejection unit 21 may perform unidirectional printing or bidirectional printing. In unidirectional printing, the ejection unit 21 ejects liquid onto the medium 99 on the forward or return path. In bidirectional printing, the ejection unit 21 ejects liquid onto the medium 99 on both the forward and return paths.

[0021] The ejection unit 21 has one or more removal electrodes. In one example, the ejection unit 21 has a first removal electrode 26 and a second removal electrode 27. The removal electrodes are mounted on the carriage 25. The removal electrodes face the medium 99. The removal electrodes are aligned with the head 22 in the first direction D1 and the second direction D2. The removal electrodes may be located in the first direction D1 relative to the head 22, or may be located in the second direction D2 relative to the head 22. That is, the removal electrodes may be located at a position offset from the head 22 in the first direction D1, or may be located at a position offset from the head 22 in the second direction D2. The first removal electrode 26 is located in the first direction D1 relative to the head 22. The second removal electrode 27 is located in the second direction D2 relative to the head 22.

[0022] When the ejection unit 21 moves back and forth, the removal electrode precedes the head 22 on the outward or return path. For example, when the ejection unit 21 moves in the first direction D1, the first removal electrode 26 precedes the head 22. That is, when the ejection unit 21 moves on the outward path, the first removal electrode 26 precedes the head 22. When the ejection unit 21 moves in the second direction D2, the second removal electrode 27 precedes the head 22. That is, when the ejection unit 21 moves on the return path, the second removal electrode 27 precedes the head 22.

[0023] A voltage is applied to the removal electrode. This makes the removal electrode a positive or negative electrode. The removal electrode becomes a positive electrode when a positive voltage is applied to it, and becomes a negative electrode when a negative voltage is applied to it. The removal electrode removes foreign matter from the medium 99 by Coulomb force. Foreign matter is paper powder, dust, etc. that adheres to the medium 99. Foreign matter may be positively or negatively charged. When a positive voltage is applied to the removal electrode, negatively charged foreign matter is attracted to the removal electrode. When a negative voltage is applied to the removal electrode, positively charged foreign matter is attracted to the removal electrode.

[0024] The removal electrode removes foreign matter from the medium 99 during printing. That is, the head 22 ejects liquid onto the medium 99 while the removal electrode removes foreign matter from the medium 99. Print quality is improved by the head 22 ejecting liquid onto the medium 99 from which foreign matter has been removed by the removal electrode preceding the head 22.

[0025] The polarity of the voltage applied to the removal electrode is switched appropriately. The polarity of the voltage applied to the removal electrode is switched between when the removal electrode is located in the transport area A1 and when it is located outside the transport area A1. When the polarity of the voltage applied to the removal electrode is switched, the foreign matter attracted to the removal electrode is repelled by the removal electrode. As a result, the removal electrode attracts the foreign matter in the transport area A1 and drops the foreign matter outside the transport area A1. Therefore, the removal electrode guides the foreign matter out of the transport area A1. The polarity of the voltage applied to the removal electrode will be explained later.

[0026] The liquid ejection device 11 includes a support section 31. The support section 31 supports a medium 99. The support section 31 is positioned to face the ejection section 21. The support section 31 supports the medium 99 on which printing is performed by the ejection section 21. The support section 31 supports the medium 99 that is transported through a transport area A1. In one example, the support section 31 defines the transport area A1.

[0027] The liquid ejection device 11 includes one or more recovery units. In one example, the liquid ejection device 11 includes a first recovery unit 32 and a second recovery unit 33. The recovery units are configured to recover foreign matter adsorbed to the removal electrode.

[0028] The recovery unit is located outside the transport area A1. The recovery unit is located in the first direction D1 or the second direction D2 relative to the transport area A1. That is, the recovery unit may be located at a position shifted in the first direction D1 relative to the transport area A1, or may be located at a position shifted in the second direction D2 relative to the transport area A1. The first recovery unit 32 is located in the first direction D1 relative to the transport area A1. The second recovery unit 33 is located in the second direction D2 relative to the transport area A1. The recovery unit is aligned with the support unit 31 in the first direction D1 and the second direction D2. More specifically, the first recovery unit 32 is located in the first direction D1 relative to the support unit 31. The second recovery unit 33 is located in the second direction D2 relative to the support unit 31.

[0029] The collection unit faces the removal electrode located outside the transport area A1. More specifically, the collection unit faces the preceding removal electrode relative to the head 22. The first collection unit 32 faces the first removal electrode 26. The first collection unit 32 faces the first removal electrode 26 that has been displaced from the transport area A1 to the outside of the transport area A1 by moving in the first direction D1. At this time, the first collection unit 32 collects foreign matter from the first removal electrode 26. The second collection unit 33 faces the second removal electrode 27. The second collection unit 33 faces the second removal electrode 27 that has been displaced from the transport area A1 to the outside of the transport area A1 by moving in the second direction D2. At this time, the second collection unit 33 collects foreign matter from the second removal electrode 27.

[0030] The collection section has a collection body. The first collection section 32 has a first collection body 34. The second collection section 33 has a second collection body 35. The collection body receives the foreign matter that falls from the removal electrode. The collection body is, for example, a container with an open top. The first collection body 34 receives the foreign matter that falls from the first removal electrode 26. The second collection body 35 receives the foreign matter that falls from the second removal electrode 27. In detail, the first collection body 34 receives the foreign matter that repels the first removal electrode 26 by switching the polarity of the voltage applied to the first removal electrode 26. The second collection body 35 receives the foreign matter that repels the second removal electrode 27 by switching the polarity of the voltage applied to the second removal electrode 27.

[0031] The collector has a bottom surface. The first collector 34 has a first bottom surface 36. The second collector 35 has a second bottom surface 37. The bottom surface is a surface that receives the foreign matter that falls from the removal electrode. The first bottom surface 36 receives the foreign matter that falls from the first removal electrode 26. The second bottom surface 37 receives the foreign matter that falls from the second removal electrode 27.

[0032] The collection section may have a collection electrode. In one example, the first collection section 32 has a first collection electrode 38. The second collection section 33 has a second collection electrode 39. The collection electrodes are attached to the collection body. In one example, the collection electrodes are located on the bottom surface. The first collection electrode 38 is located on the first bottom surface 36. The second collection electrode 39 is located on the second bottom surface 37.

[0033] A voltage is applied to the recovery electrode. This makes the recovery electrode a positive electrode or a negative electrode. The recovery electrode becomes a positive electrode when a positive voltage is applied to it, and becomes a negative electrode when a negative voltage is applied to it. The recovery electrode recovers foreign matter from the removal electrode by Coulomb force. The recovery electrode makes it easier for foreign matter to enter the recovery body from the removal electrode. The recovery electrode guides negatively charged foreign matter to the recovery body when a positive voltage is applied to it. The recovery electrode guides positively charged foreign matter to the recovery body when a negative voltage is applied to it.

[0034] The polarity of the voltage applied to the recovery electrodes is invariable. That is, a positive voltage or a negative voltage is applied to the first recovery electrode 38. A positive voltage or a negative voltage is applied to the second recovery electrode 39. The polarity of the voltage applied to the recovery electrodes will be described later.

[0035] The voltage applied to the first collection electrode 38 and the voltage applied to the second collection electrode 39 may be of the same polarity or different polarities. For example, when a positive voltage is applied to both the first collection electrode 38 and the second collection electrode 39, the first collection unit 32 and the second collection unit 33 can collect negatively charged foreign matter. In one example, the voltage applied to the first collection electrode 38 and the voltage applied to the second collection electrode 39 have different polarities. This allows both positively charged foreign matter and negatively charged foreign matter to be collected by the first collection unit 32 and the second collection unit 33.

[0036] The liquid ejection device 11 includes a power supply circuit 41. The power supply circuit 41 is a circuit that applies a voltage to the removal electrode. The power supply circuit 41 is connected to the removal electrode. In one example, the power supply circuit 41 is connected to the first removal electrode 26 and the second removal electrode 27. The power supply circuit 41 is configured to apply a positive voltage and a negative voltage to the removal electrode. The power supply circuit 41 switches the polarity of the voltage applied to the first removal electrode 26. The power supply circuit 41 switches the polarity of the voltage applied to the second removal electrode 27. The power supply circuit 41 may apply a voltage to the removal electrode while the power supply of the liquid ejection device 11 is ON, or may apply a voltage to the removal electrode only while the liquid ejection device 11 is performing printing.

[0037] The power supply circuit 41 may apply a voltage to the recovery electrode. The power supply circuit 41 may be connected to the recovery electrode. In one example, the power supply circuit 41 is connected to the first recovery electrode 38 and the second recovery electrode 39. The power supply circuit 41 is configured to apply a positive voltage or a negative voltage to the recovery electrode. The power supply circuit 41 applies a positive voltage or a negative voltage to the first recovery electrode 38. The power supply circuit 41 applies a positive voltage or a negative voltage to the second recovery electrode 39. The power supply circuit 41 may apply a voltage to the recovery electrode while the power supply of the liquid ejection device 11 is ON, or may apply a voltage to the removal electrode only while the liquid ejection device 11 is performing printing.

[0038] The liquid ejection device 11 may include a plurality of power supply circuits 41. For example, the liquid ejection device 11 includes a removal power supply circuit that applies a voltage to the removal electrode, and a recovery power supply circuit that applies a voltage to the recovery electrode.

[0039] The liquid ejection device 11 includes a detection unit 42. The detection unit 42 detects whether the opening / closing body 17 is opened or closed. More specifically, the detection unit 42 detects that the opening / closing body 17 is opened. The detection unit 42 may be a pressure sensor or an optical sensor. The detection unit 42 is attached to the housing 12 or the opening / closing body 17.

[0040] The liquid ejection device 11 includes a control unit 43. The control unit 43 may be configured with one or more processors that execute various processes according to a computer program. The control unit 43 may be configured with one or more dedicated hardware circuits, such as an application specific integrated circuit, that executes at least a part of the various processes. The control unit 43 may be configured as a circuit including a combination of a processor and a hardware circuit. The processor includes a CPU and a memory, such as a RAM and a ROM. The memory stores program code or instructions configured to cause the CPU to execute a process. The memory, i.e., a computer-readable medium, includes any readable medium that can be accessed by a general-purpose or dedicated computer.

[0041] The control unit 43 controls the power supply circuit 41. In this way, the control unit 43 controls the voltage applied to the removal electrode. More specifically, the control unit 43 switches the polarity of the voltage applied to the removal electrode. The control unit 43 controls the voltage applied to the recovery electrode. The control unit 43 may control the discharge unit 21 in addition to the power supply circuit 41. In one example, the control unit 43 comprehensively controls the liquid discharge device 11.

[0042] The control unit 43 controls the power supply circuit 41 based on the detection result of the detection unit 42. More specifically, when the detection unit 42 detects that the opening / closing body 17 is opened, the control unit 43 stops the application of voltage. The control unit 43 stops the application of voltage to the removal electrode and the recovery electrode by the power supply circuit 41. At this time, the control unit 43 also stops the supply of voltage to the recovery electrode. That is, even if the power supply of the liquid discharger 11 is ON, when the opening / closing body 17 is opened, the supply of voltage to the removal electrode and the recovery electrode is stopped. When the opening / closing body 17 is opened, the user may insert his / her hand into the housing 12. That is, the user may touch the removal electrode and the recovery electrode. By stopping the supply of voltage to the electrodes, the user can safely access the housing 12.

[0043] <Control of applied voltage> Next, there will be described control of the applied voltage by the control unit 43. The control unit 43 controls the applied voltage to the removal electrode and the recovery electrode.

[0044] The control unit 43 switches the polarity of the voltage applied to the removal electrode between when the removal electrode faces the medium 99 and when the removal electrode faces the recovery unit. In detail, when the discharge unit 21 moves on the forward or backward path, the control unit 43 switches the polarity of the voltage applied to the removal electrode preceding the head 22 between when the removal electrode faces the medium 99 and when the removal electrode faces the recovery unit.

[0045] As shown in FIG. 3 and FIG. 4, when the discharge unit 21 moves in the first direction D1, the control unit 43 switches the polarity of the voltage applied to the first removal electrode 26 between when the first removal electrode 26 faces the medium 99 and when the first collection unit 32 faces the medium 99. In one example, when the discharge unit 21 moves in the first direction D1, the control unit 43 applies a negative voltage to the first removal electrode 26 when the first removal electrode 26 is located in the transport area A1. This removes positively charged foreign matter from the medium 99. When the discharge unit 21 moves in the first direction D1, the control unit 43 applies a positive voltage to the first removal electrode 26 when the first removal electrode 26 faces the first collection unit 32. That is, the control unit 43 switches the polarity of the voltage applied to the first removal electrode 26 in the process of the discharge unit 21 moving in the first direction D1. The foreign matter falls by being repelled by the first removal electrode 26. When the discharger 21 moves in the second direction D2, the control unit 43 may keep a positive voltage applied to the first removal electrode 26, or may apply a negative voltage to the first removal electrode 26. When the discharger 21 moves in the second direction D2, the control unit 43 applies a negative voltage to the first removal electrode 26 when the first removal electrode 26 faces the medium 99, so that the first removal electrode 26 can remove foreign matter on the return path as well.

[0046] The control unit 43 applies to the first collection electrode 38 a voltage of a polarity different from the polarity of the voltage applied to the first removal electrode 26 when the first removal electrode 26 faces the first collection unit 32. In one example, the control unit 43 applies a negative voltage to the first collection electrode 38. This allows the first collection unit 32 to effectively collect the foreign matter repelled by the first removal electrode 26.

[0047] The control unit 43 may apply a positive voltage to the first removal electrode 26 when the first removal electrode 26 faces the medium 99. In this case, the control unit 43 applies a negative voltage to the first removal electrode 26 when the first removal electrode 26 faces the first collection unit 32. Furthermore, the control unit 43 applies a positive voltage to the first removal electrode 38.

[0048] As shown in FIG. 5 and FIG. 6, when the discharger 21 moves in the second direction D2, the control unit 43 switches the polarity of the voltage applied to the second removal electrode 27 between when the second removal electrode 27 faces the medium 99 and when it faces the second collection unit 33. In one example, when the discharger 21 moves in the second direction D2, the control unit 43 applies a positive voltage to the second removal electrode 27 when the second removal electrode 27 is located in the transport area A1. This removes negatively charged foreign matter from the medium 99. When the discharger 21 moves in the second direction D2, the control unit 43 applies a negative voltage to the second removal electrode 27 when the second removal electrode 27 faces the second collection unit 33. That is, the control unit 43 switches the polarity of the voltage applied to the second removal electrode 27 in the process of the discharger 21 moving in the second direction D2. The foreign matter falls by being repelled by the second removal electrode 27. When the discharger 21 moves in the first direction D1, the control unit 43 may keep a negative voltage applied to the second removal electrode 27, or may apply a positive voltage to the second removal electrode 27. When the discharger 21 moves in the first direction D1, the control unit 43 applies a positive voltage to the second removal electrode 27 when the second removal electrode 27 faces the medium 99, so that the second removal electrode 27 can remove foreign matter even on the forward path.

[0049] The control unit 43 applies to the second collection electrode 39 a voltage of a different polarity from the polarity of the voltage applied to the second removal electrode 27 when the second removal electrode 27 faces the second collection unit 33. In one example, the control unit 43 applies a positive voltage to the second collection electrode 39. This allows the second collection unit 33 to effectively collect the foreign matter repelled by the second removal electrode 27.

[0050] The control unit 43 may apply a negative voltage to the second removal electrode 27 when the second removal electrode 27 faces the medium 99. In this case, the control unit 43 applies a positive voltage to the second removal electrode 27 when the second removal electrode 27 faces the second collection unit 33. Furthermore, the control unit 43 applies a negative voltage to the second collection electrode 39.

[0051] The control unit 43 may control the power supply circuit 41 so that the polarity of the voltage applied to the first removal electrode 26 when the first removal electrode 26 faces the medium 99 is different from the polarity of the voltage applied to the second removal electrode 27 when the second removal electrode 27 faces the medium 99. That is, the polarity of the voltage applied to the first removal electrode 26 when the first removal electrode 26 faces the medium 99 is different from the polarity of the voltage applied to the second removal electrode 27 when the second removal electrode 27 faces the medium 99. In detail, the polarity of the voltage applied to the first removal electrode 26 when the first removal electrode 26 faces the medium 99 when the discharge unit 21 moves in the first direction D1 is different from the polarity of the voltage applied to the second removal electrode 27 when the second removal electrode 27 faces the medium 99 when the discharge unit 21 moves in the second direction D2. As a result, both positively charged foreign matter and negatively charged foreign matter are removed by the first removal electrode 26 and the second removal electrode 27. In this case, the polarity of the voltage applied to first collecting electrode 38 and the polarity of the voltage applied to second collecting electrode 39 are different.

[0052] <Action and Effects> Next, the operation and effects of the above embodiment will be described. (1) When the discharge unit 21 moves in the first direction D1, the control unit 43 switches the polarity of the voltage applied to the first removal electrode 26 between when the first removal electrode 26 faces the medium 99 and when the first collection unit 32 faces the medium 99. According to the above configuration, when the first removal electrode 26 faces the medium 99, the first removal electrode 26 removes foreign matter from the medium 99 by Coulomb force. When the polarity of the voltage applied to the first removal electrode 26 is switched, the first removal electrode 26 and the foreign matter are repelled. Therefore, when the first removal electrode 26 faces the first collection unit 32, the first removal electrode 26 drops the foreign matter toward the first collection unit 32. By the first collection unit 32 collecting the foreign matter, the risk of the foreign matter adhering to the head 22 is reduced. Therefore, the foreign matter can be appropriately removed from the medium 99.

[0053] (2) The control unit 43 applies to the first collection electrode 38 a voltage of a different polarity from the polarity of the voltage applied to the first removal electrode 26 when the first removal electrode 26 faces the first collection unit 32. According to the above configuration, foreign matter that repels the first removal electrode 26 is attracted to the first collection electrode 38. In other words, it becomes easier for the first collection unit 32 to collect foreign matter.

[0054] (3) When the discharge unit 21 moves in the second direction D2, the control unit 43 switches the polarity of the voltage applied to the second removal electrode 27 between when the second removal electrode 27 faces the medium 99 and when the second removal electrode 27 faces the second collection unit 33. According to the above configuration, when the discharge unit 21 moves in the second direction D2, the second removal electrode 27 can remove foreign matter from the medium 99.

[0055] (4) The control unit 43 applies to the second collection electrode 39 a voltage of a polarity different from the polarity of the voltage applied to the second removal electrode 27 when the second removal electrode 27 faces the second collection unit 33. According to the above configuration, foreign matter that repels the second removal electrode 27 is attracted to the second collection electrode 39. In other words, it becomes easier for the second collection unit 33 to collect foreign matter.

[0056] (5) The polarity of the voltage applied to the first removal electrode 26 when the first removal electrode 26 faces the medium 99 is different from the polarity of the voltage applied to the second removal electrode 27 when the second removal electrode 27 faces the medium 99. The polarity of the voltage applied to the first collection electrode 38 is different from the polarity of the voltage applied to the second collection electrode 39. According to the above configuration, the first collection unit 32 and the second collection unit 33 can collect both positively charged foreign matter and negatively charged foreign matter.

[0057] (6) The control unit 43 stops the application of the voltage when the detection unit 42 detects that the opening / closing body 17 is opened. According to the above configuration, the risk that the user will touch the electrode to which the voltage is applied is reduced.

[0058] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modified examples can be combined with each other to the extent that there is no technical contradiction.

[0059] The discharge unit 21 may move in the second direction D2 when moving on the outward path. That is, the discharge unit 21 may move in the first direction D1 when moving on the return path. The recovery electrode may be embedded in the recovery body.

[0060] The liquid ejected by the ejection unit 21 is not limited to ink, and may be, for example, a liquid in which particles of a functional material are dispersed or mixed in a liquid. For example, the ejection unit 21 may eject a liquid containing, in a dispersed or dissolved form, a material such as an electrode material or a pixel material used in the manufacture of liquid crystal displays, electroluminescence displays, and surface-emitting displays.

[0061] <Technical philosophy> The technical ideas and effects obtained from the above-mentioned embodiment and modified examples will be described below.

[0062] (A) A liquid ejection device includes an ejection section that ejects liquid while moving back and forth in a first direction and a second direction relative to a medium transported through a transport region, a recovery section that is positioned in the first direction relative to the transport region, and a control section, wherein the ejection section has a head having a nozzle face through which nozzles that eject liquid open, and a removal electrode that is positioned in the first direction relative to the head and to which a voltage is applied, and when the ejection section moves in the first direction, the control section switches the polarity of the voltage applied to the removal electrode between when the removal electrode faces the medium and when it faces the recovery section.

[0063] According to the above configuration, when the removal electrode faces the medium, it removes foreign matter from the medium by Coulomb force. When the polarity of the voltage applied to the removal electrode is switched, the removal electrode and the foreign matter are repelled. Therefore, when the removal electrode faces the collection section, it causes the foreign matter to fall toward the collection section. By the collection section collecting the foreign matter, the risk of the foreign matter adhering to the head is reduced. Therefore, the foreign matter can be appropriately removed from the medium.

[0064] (B) In the liquid ejection device, the recovery unit may have a recovery electrode, and the control unit may apply to the recovery electrode a voltage of a different polarity from a voltage applied to the removal electrode when the removal electrode faces the recovery unit. According to the above configuration, foreign matter that repels the removal electrode is attracted to the recovery electrode. In other words, the recovery unit can easily recover the foreign matter.

[0065] (C) In the above liquid ejection device, the recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery section located in the second direction relative to the transport region, the ejection section has a second removal electrode located in the second direction relative to the head, and the control section may switch the polarity of the voltage applied to the second removal electrode between when the second removal electrode faces the medium and when it faces the second recovery section when the ejection section moves in the second direction. With the above configuration, the second removal electrode can remove foreign matter from the medium when the ejection section moves in the second direction.

[0066] (D) In ​​the above liquid ejection device, the recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery section located in the second direction relative to the transport region, the ejection section has a second removal electrode located in the second direction relative to the head, and the control section may switch the polarity of the voltage applied to the second removal electrode between when the second removal electrode faces the medium and when it faces the second recovery section when the ejection section moves in the second direction. With the above configuration, when the ejection section moves in the second direction, the second removal electrode can remove foreign matter from the medium.

[0067] (E) In the above liquid ejection device, the second collection unit may have a collection electrode, and the control unit may apply to the collection electrode a voltage of a polarity different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces the second collection unit. According to the above configuration, foreign matter that repels the second removal electrode is attracted to the collection electrode. In other words, the second collection unit can easily collect the foreign matter.

[0068] (F) In the above liquid ejection device, the recovery electrode may be a first recovery electrode, the second recovery section may have a second recovery electrode, and the control section may apply to the second recovery electrode a voltage of a different polarity from a voltage applied to the second removal electrode when the second removal electrode faces the second recovery section. According to the above configuration, foreign matter that repels the second removal electrode is attracted to the second recovery electrode. In other words, the second recovery section can easily recover foreign matter.

[0069] (G) In the liquid ejection device, the polarity of the voltage applied to the first removal electrode when the first removal electrode faces the medium may be different from the polarity of the voltage applied to the second removal electrode when the second removal electrode faces the medium, and the polarity of the voltage applied to the first recovery electrode may be different from the polarity of the voltage applied to the second recovery electrode. With the above configuration, both positively charged foreign matter and negatively charged foreign matter can be recovered.

[0070] (H) The liquid ejection device may include a housing that houses the ejection unit, an opening / closing body that is attached to the housing so as to open and close and exposes the ejection unit by opening the opening relative to the housing, and a detection unit that detects that the opening / closing body has been opened, and the control unit may stop applying a voltage when the detection unit detects that the opening / closing body has been opened. With the above configuration, the risk of a user touching an electrode to which a voltage is applied is reduced.

[0071] (I) A method for controlling a liquid ejection device, comprising: an ejection section that ejects liquid while reciprocating in a first direction and a second direction relative to a medium transported in a transport region; and a recovery section located in the first direction relative to the transport region, the ejection section having a head having a nozzle face in which nozzles that eject liquid are opening, and a removal electrode located in the first direction relative to the head and to which a voltage is applied, the method including, when the ejection section moves in the first direction, switching the polarity of the voltage applied to the removal electrode between when the removal electrode faces the medium and when the removal electrode faces the recovery section. The above method provides the same effects as the liquid ejection device described above.

[0072] (J) The method of controlling the liquid ejection device may include applying, to the recovery electrode of the recovery section, a voltage having a polarity different from a polarity of a voltage applied to the removal electrode when the removal electrode faces the recovery section. According to the method, the same effect as that of the liquid ejection device described above can be obtained.

[0073] (K) In the above-mentioned method for controlling the liquid ejection device, the recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery section located in the second direction relative to the transport region, and the ejection section has a second removal electrode located in the second direction relative to the head, and the method for controlling the liquid ejection device may include switching the polarity of the voltage applied to the second removal electrode when the ejection section moves in the second direction between when the second removal electrode faces the medium and when it faces the second recovery section. According to the above-mentioned method, the same effect as that of the above-mentioned liquid ejection device can be obtained.

[0074] (L) In the above-mentioned method for controlling a liquid ejection device, the recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery section located in the second direction relative to the transport region, and the ejection section has a second removal electrode located in the second direction relative to the head, and the method for controlling a liquid ejection device may switch the polarity of a voltage applied to the second removal electrode when the ejection section moves in the second direction between when the second removal electrode faces the medium and when it faces the second recovery section. According to the above-mentioned method, the same effect as that of the above-mentioned liquid ejection device can be obtained.

[0075] (M) The method of controlling the liquid ejection device may include applying, to the recovery electrode of the second recovery unit, a voltage having a polarity different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces the second recovery unit. According to the method, the same effect as that of the liquid ejection device described above can be obtained.

[0076] (N) In the above-mentioned method for controlling the liquid ejection device, the recovery electrode may be a first recovery electrode, and the method for controlling the liquid ejection device may include applying, to the second recovery electrode of the second recovery section, a voltage having a polarity different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces the second recovery section. According to the above-mentioned method, the same effect as that of the above-mentioned liquid ejection device can be obtained.

[0077] (O) The method of controlling the liquid ejection device may include applying, when the first removal electrode faces a medium, a voltage having a polarity different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces a medium, to the first removal electrode, and applying, when the first removal electrode faces a medium, a voltage having a polarity different from a polarity of a voltage applied to the second recovery electrode, to the first recovery electrode. According to the above method, the same effect as that of the liquid ejection device described above can be obtained. [Explanation of symbols]

[0078] 11...liquid ejection device, 12...housing, 13...supply port, 14...discharge port, 15...supply tray, 16...discharge tray, 17...opening / closing body, 18...operation panel, 21...ejection section, 22...head, 23...nozzle, 24...nozzle surface, 25...carriage, 26...first removal electrode, 27...second removal electrode, 31...support section, 32...first recovery section, 33...second recovery section, 34...first recovery body, 35...second recovery body, 36...first bottom surface, 37...second bottom surface, 38...first recovery electrode, 39...second recovery electrode, 41...power supply circuit, 42...detection section, 43...control section, 99...medium, A1...transport area, D1...first direction, D2...second direction, Y1...transport direction.

Claims

1. a discharge unit that discharges liquid while reciprocating in a first direction and a second direction toward a medium transported in a transport region; A recovery section located in the first direction relative to the transport region; A control unit, The discharge unit is a head having a nozzle surface on which nozzles for ejecting liquid are opened; a removal electrode located in the first direction relative to the head and to which a voltage is applied; The liquid ejection device is characterized in that, when the ejection section moves in the first direction, the control section switches the polarity of the voltage applied to the removal electrode when the removal electrode faces the medium and when the removal electrode faces the recovery section.

2. The recovery unit has a recovery electrode, The liquid ejection device according to claim 1 , wherein the control unit applies to the recovery electrode a voltage having a polarity different from a polarity of a voltage applied to the removal electrode when the removal electrode faces the recovery unit.

3. The recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery unit located in the second direction relative to the transport region; the ejection section has a second removal electrode located in the second direction relative to the head, The liquid ejection device according to claim 1, characterized in that, when the ejection section moves in the second direction, the control section switches the polarity of the voltage applied to the second removal electrode when the second removal electrode faces a medium and when the second removal electrode faces the second recovery section.

4. The recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery unit located in the second direction relative to the transport region; the ejection section has a second removal electrode located in the second direction relative to the head, The liquid ejection device according to claim 2, characterized in that, when the ejection section moves in the second direction, the control section switches the polarity of the voltage applied to the second removal electrode when the second removal electrode faces a medium and when the second removal electrode faces the second recovery section.

5. The second recovery unit has a recovery electrode, The liquid ejection device according to claim 3 , wherein the control unit applies to the recovery electrode a voltage of a polarity different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces the second recovery unit.

6. the recovery electrode is a first recovery electrode, the second collection section has a second collection electrode, The liquid ejection device according to claim 4 , wherein the control unit applies to the second recovery electrode a voltage of a different polarity from a voltage applied to the second removal electrode when the second removal electrode faces the second recovery unit.

7. a polarity of a voltage applied to the first removal electrode when the first removal electrode faces a medium is different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces a medium; 7. The liquid ejection device according to claim 6, wherein a polarity of the voltage applied to the first recovery electrode is different from a polarity of the voltage applied to the second recovery electrode.

8. A housing that houses the ejection unit; an opening / closing body that is attached to the housing so as to be opened and closed, and that exposes the discharge portion by opening the opening / closing body to the housing; A detection unit that detects that the opening / closing body is opened, 8. The liquid ejection device according to claim 1, wherein the control unit stops the application of the voltage when the detection unit detects that the opening / closing body is opened.

9. a discharge unit that discharges liquid while reciprocating in a first direction and a second direction toward a medium transported in a transport region; a recovery section located in the first direction relative to the transport region, The discharge unit is a head having a nozzle surface on which nozzles for ejecting liquid are opened; a removal electrode that is positioned in the first direction with respect to the head and to which a voltage is applied, A control method for a liquid ejection device, characterized in that when the ejection section moves in the first direction, the polarity of a voltage applied to the removal electrode is switched between when the removal electrode faces a medium and when the removal electrode faces the recovery section.

10. A method for controlling a liquid ejection device according to claim 9, characterized in that the method includes applying a voltage of a polarity different from the polarity of the voltage applied to the removal electrode when the removal electrode faces the recovery section to the recovery electrode of the recovery section.

11. The recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery unit located in the second direction relative to the transport region; the ejection section has a second removal electrode located in the second direction relative to the head, The control method for a liquid ejection device according to claim 9, characterized in that, when the ejection section moves in the second direction, the polarity of the voltage applied to the second removal electrode is switched between when the second removal electrode faces a medium and when the second removal electrode faces the second recovery section.

12. The recovery section is a first recovery section, the removal electrode is a first removal electrode, the liquid ejection device includes a second recovery unit located in the second direction relative to the transport region; the ejection section has a second removal electrode located in the second direction relative to the head, The control method for a liquid ejection device according to claim 10, characterized in that, when the ejection section moves in the second direction, the polarity of the voltage applied to the second removal electrode is switched between when the second removal electrode faces a medium and when the second removal electrode faces the second recovery section.

13. A method for controlling a liquid ejection device as described in claim 11, characterized in that it includes applying a voltage of a polarity different from the polarity of the voltage applied to the second removal electrode when the second removal electrode faces the second recovery section to the recovery electrode of the second recovery section.

14. the recovery electrode is a first recovery electrode, The control method for a liquid ejection device according to claim 12, characterized in that the control method for the liquid ejection device includes applying, to a second recovery electrode of the second recovery section, a voltage of a polarity different from the polarity of the voltage applied to the second removal electrode when the second removal electrode faces the second recovery section.

15. applying a voltage having a polarity different from a polarity of a voltage applied to the second removal electrode when the second removal electrode faces the medium to the first removal electrode when the first removal electrode faces the medium; 15. The method of controlling a liquid ejection device according to claim 14, further comprising: applying, to the first recovery electrode, a voltage having a polarity different from a polarity of the voltage applied to the second recovery electrode.

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