Dielectric heating device and liquid ejection system

Abstract

The present application relates to a dielectric heating device and a liquid ejection system, in the dielectric heating device, a heating control section performs heating control in at least one of a forward path in which a first electrode unit is oriented in one direction of a scanning direction and a return path in which the first electrode unit is oriented in the opposite direction, the heating control section controls a voltage application section that applies an alternating voltage to a first electrode and a second electrode of the first electrode unit and a moving section that reciprocally moves a carriage on which the first electrode unit is mounted, and the heating control is heating of a medium while moving the first electrode unit in the scanning direction. In the heating control, the heating control section sets an electric field intensity of the first electrode unit to a first electric field intensity when the first electrode unit is positioned at a first location overlapping with an end portion of the medium, sets the electric field intensity to a second electric field intensity stronger than the first electric field intensity when the first electrode unit is positioned at a second location overlapping with a central portion of the medium, and makes a moving speed of the first electrode unit at the first location slower than a moving speed at the second location.

Description

Technical Field

[0001] This disclosure relates to dielectric heating devices and liquid ejection systems. Background Technology

[0002] Regarding dielectric heating devices, Patent Document 1 describes a drying unit having multiple microwave irradiation devices. This drying unit is fixed to the inkjet printer body and has a length capable of heating and drying the entire width of the printing area of ​​the printed material along the main scanning direction. In the drying unit, multiple microwave irradiation devices are arranged along the main scanning direction.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2011-37228

[0004] In Patent Document 1, the wider the printed material to be heated, the more necessary it is to increase the size of the microwave irradiation device or the number of microwave irradiation devices. Therefore, research is underway to suppress such large-scale construction by mounting the dielectric heating device on a carriage configured to reciprocate along the width direction. However, in this case, for example, deviations in the amount of heating may occur in the direction of carriage movement due to changes in the carriage's moving speed or direction. Summary of the Invention

[0005] According to a first aspect of this disclosure, a dielectric heating device is provided. This dielectric heating device includes: a first electrode unit having a first electrode and a second electrode facing a dielectric material, and heating the dielectric material by dielectric heating; a voltage application unit applying an alternating current voltage to the first electrode and the second electrode; a carriage carrying the first electrode unit; a movement unit that reciprocates the first electrode unit along the scanning direction at least on the dielectric material by reciprocating the carriage along the scanning direction; and a heating control unit controlling the voltage application unit and the movement unit. The heating control unit performs heating control in at least one of a path from the first electrode unit toward the scanning direction and a loop in the opposite direction of the first electrode unit, wherein the heating control refers to heating the dielectric material while moving the first electrode unit along the scanning direction. In the heating control, when the first electrode unit is located at a first location overlapping one end of the medium in the scanning direction, the heating control unit sets the electric field strength formed by the first electrode unit to a first electric field strength. When the first electrode unit is located at a second location overlapping the center of the medium in the scanning direction, the heating control unit sets the electric field strength formed by the first electrode unit to a second electric field strength that is stronger than the first electric field strength, so that the moving speed of the first electrode unit at the first location is slower than the moving speed of the first electrode unit at the second location.

[0006] According to a second aspect of this disclosure, a liquid ejection system is provided. This liquid ejection system includes a dielectric heating device as described above, a liquid ejection section having an ejection surface with a nozzle opening and ejecting liquid from the nozzle opening to the medium and coating it, and an ejection control section for controlling the liquid ejection section. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the general configuration of the liquid ejection system as a first embodiment.

[0008] Figure 2 This is a top view showing the schematic configuration of the dielectric heating device in the first embodiment.

[0009] Figure 3 It is a three-dimensional diagram showing the general structure of the electrode unit.

[0010] Figure 4 This is an explanatory diagram showing the movement of the carriage in the first embodiment.

[0011] Figure 5 This is an explanatory diagram showing the heating area of ​​the first electrode unit.

[0012] Figure 6 This is an explanatory diagram showing the relationship between the position of the carriage and the electric field strength in the first embodiment.

[0013] Figure 7 This is an explanatory diagram showing the relationship between the position of the carriage and the moving speed in the first embodiment.

[0014] Figure 8 This is an explanatory diagram showing the movement of the carriage in the second embodiment.

[0015] Figure 9 This is a top view showing the general configuration of the liquid ejection system in the third embodiment.

[0016] Figure 10 This is an illustration of the sealing process implemented by the lid.

[0017] Figure 11 This is an explanatory diagram showing the positional relationship between the first electrode unit and the cover.

[0018] Figure 12 This is an explanatory diagram showing the relationship between the carriage position and the electric field strength in the third embodiment.

[0019] Figure 13 This is an explanatory diagram showing the relationship between the carriage position and the moving speed in the reference example.

[0020] Explanation of reference numerals in the attached figures

[0021] 20…Electrode unit, 30…First electrode unit, 31…First electrode, 32…Second electrode, 33…Connecting component, 34…First coil, 35…Wire, 40…Second electrode unit, 41…Third electrode, 42…Fourth electrode, 44…Second coil, 80…Voltage application part, 100, 100b…Dielectric heating device, 110…Substrate, 120, 120b…Slide carriage, 130…Moving part, 131…Annular belt, 132…Pulley, 133…Driver 140… airflow generating section, 180… heating control section, 200, 200b… liquid ejection system, 205, 205b… liquid ejection device, 210… liquid ejection section, 211… nozzle opening, 212… nozzle surface, 213… ejection surface, 220… cover, 221… bottom, 222… edge, 250, 250b… ejection control section, 320, 320b… conveying section, 321… first conveying section, 322… second conveying section, 323… roller. Detailed Implementation

[0022] A. First implementation method:

[0023] Figure 1 This is a schematic diagram showing the general configuration of the liquid ejection system 200 as a first embodiment. Figure 1 The diagram shows arrows indicating mutually orthogonal X, Y, and Z directions. The X and Y directions are parallel to the horizontal plane, and the Z direction is vertically upward. The arrows indicating the X, Y, and Z directions are also shown in the diagram in other figures. Figure 1 The corresponding methods are illustrated appropriately. In the following description, when the orientation is determined, the direction indicated by the arrow in each diagram is marked as "+", and the opposite direction is marked as "-", and positive and negative signs are used in the direction markings. Hereinafter, the +Z direction is also referred to as "up", and the -Z direction is also referred to as "down". In addition, in this specification, orthogonality includes a range of 90° ± 10°.

[0024] The liquid ejection system 200 includes a dielectric heating device 100 and a liquid ejection device 205. The dielectric heating device 100 has an electrode unit 20. Additionally, the liquid ejection system 200 in this embodiment also includes a conveying section 320. The liquid ejection system 200 conveys a medium Md through the conveying section 320, and the liquid is ejected and coated onto the medium Md by the liquid ejection device 205. The electrode unit 20 of the dielectric heating device 100 heats the liquid coated onto the medium Md to dry it. Alternatively, the liquid ejection device 205 can be described as applying the liquid heated by the electrode unit 20 onto the medium Md. The electrode unit 20 is also referred to as a heater.

[0025] The medium Md can be, for example, paper, cloth, or film. The cloth used as the medium Md is formed, for example, by weaving fibers of cotton or linen, polyester, silk, rayon, or fibers blended from these. In this embodiment, sheet-like cotton cloth is used as the medium Md. The liquid applied to the medium Md can be, for example, various inks. In this embodiment, a water-based ink with water as its main component is used as the liquid. In this specification, the main component of a liquid refers to a substance whose mass fraction is 50% or more. In other embodiments, besides inks, any liquid other than various color materials, electrode materials, organic or inorganic biological samples, lubricating oils, resin solutions, etching solutions, etc., can also be used as the liquid.

[0026] The conveying unit 320 conveys the medium Md. In this embodiment, the conveying unit 320 is configured as a roller mechanism that conveys the medium Md via a drive roller 323. The conveying unit 320 has a first conveying unit 321 and a second conveying unit 322. The first conveying unit 321 is disposed in the liquid ejection device 205 and conveys the medium Md in the liquid ejection device 205. The second conveying unit 322 is disposed in the dielectric heating device 100 and conveys the medium Md in the dielectric heating device 100. The first conveying unit 321 and the second conveying unit 322 each have a roller 323 and a drive unit (not shown), which is composed of a motor or the like for driving the roller 323. In other embodiments, the conveying unit 320 may, for example, be configured as a conveying mechanism that conveys the medium Md via a drive conveyor belt.

[0027] The first conveying unit 321 is positioned in the +Y direction of the second conveying unit 322. In this embodiment, the first conveying unit 321 and the second conveying unit 322 perform intermittent conveying of the sheet-like medium Md in the -Y direction. More specifically, the first conveying unit 321 and the second conveying unit 322 alternately and repeatedly perform conveying operations and stationary operations. The conveying operation is the operation of moving the roller 323 to convey the medium Md a predetermined conveying distance in the -Y direction, and the stationary operation is the operation of not moving the roller 323, that is, not conveying the medium Md and remaining stationary. The direction in which the medium Md is conveyed by the conveying unit 320 is also called the conveying direction. The conveying direction is the direction that intersects the scanning direction described later, and in this embodiment it is the -Y direction.

[0028] In this embodiment, the liquid ejection device 205 is configured as an inkjet printer that performs printing by ejecting and coating liquid ink onto the medium Md. Therefore, the liquid ejection system 200 can also be described as a printing system equipped with an inkjet printer. The liquid ejection device 205 includes a liquid ejection section 210 that ejects and coats liquid onto the medium Md, an ejection control section 250, and the aforementioned first transport section 321.

[0029] The liquid ejection section 210 is configured as a piezoelectric or thermal liquid ejection head, for example, and has one or more nozzle tips (not shown). Each nozzle tip has a nozzle surface 212 with a nozzle opening 211, which is the opening of the nozzle from which liquid is ejected. Each nozzle surface 212 constitutes the ejection surface 213 of the liquid ejection section 210. In other words, it can be said that the liquid ejection section 210 has an ejection surface 213 with a nozzle opening 211. The liquid ejection section 210 ejects ink as a liquid from the nozzle opening 211 onto the medium Md. The ink ejected from each nozzle tip of the liquid ejection section 210 can be the same color or different color. In addition, the liquid ejection section 210 can be configured to reciprocate relative to the medium Md in a direction orthogonal to the Z direction and intersecting the Y direction, or it can be configured as a fixed position without reciprocating relative to the medium Md, a so-called traveling head.

[0030] In this embodiment, the ink used as a liquid is a pigment ink containing resin. The resin contained in the ink has the function of firmly fixing the pigment onto the medium Md by itself. Such resins are used, for example, in a state in which resins that are sparingly soluble or insoluble in solvents such as water are formed into particulates and dispersed in the solvent, i.e., in an emulsion state or a suspension state. Examples of such resins include acrylic resins, styrene acrylic resins, fluorene resins, urethane resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, ethylene vinyl acetate resins, etc. Two or more of these resins may also be used simultaneously. Such resins are also referred to as resin.

[0031] The ejection control unit 250 is configured as a computer having one or more processors, a storage device, and an input / output interface for signal input and output to the outside. In this embodiment, the ejection control unit 250 controls the liquid ejection unit 210 and the first conveying unit 321 to convey the medium Md in the -Y direction and eject and adhere liquid to the medium Md. More specifically, the ejection control unit 250 repeatedly ejects liquid to the medium Md during the stationary operation of the first conveying unit 321, and moves the medium Md in the -Y direction during the conveying operation of the first conveying unit 321, while simultaneously printing relative to the medium Md. In other embodiments, the ejection control unit 250 may, for example, be configured as a combination of multiple circuits.

[0032] Figure 2 This is a top view showing the schematic configuration of the dielectric heating device 100 in the first embodiment. (See attached image.) Figure 1 and Figure 2As shown, the dielectric heating device 100 includes: an electrode unit 20 for heating a dielectric medium Md by dielectric heating, a voltage application unit 80 for applying an alternating current voltage to the electrode unit 20, a carriage 120 for mounting the electrode unit 20, a moving unit 130 for reciprocating the carriage 120, a heating control unit 180, and the aforementioned second conveying unit 322. Furthermore, the dielectric heating device 100 of this embodiment is provided with an airflow generating unit 140 for generating airflow. In this embodiment, the airflow generating unit 140 is configured as a blower that blows air toward the dielectric Md. The airflow generating unit 140 can, for example, promote the drying of the dielectric Md or appropriately promote the cooling of the dielectric Md. Furthermore, in Figure 1 The carriage 120, the moving part 130, and the airflow generating part 140 are omitted in the original text.

[0033] In this embodiment, the dielectric heating device 100 uses a second conveying section 322 to convey the medium Md, and a moving section 130 to reciprocate the carriage 120, thereby causing the electrode unit 20 to reciprocate on the medium Md. Furthermore, the medium Md is heated using an alternating current electric field generated from the electrode unit 20, thereby drying the medium Md. The term "heating the medium Md by an alternating current electric field" includes not only heating the medium Md itself by the alternating current electric field, but also heating any liquid or solid adhering to the medium Md by the alternating current electric field.

[0034] The voltage application unit 80 is electrically connected to the first electrode 31 and the second electrode 32 of the first electrode unit 30, which will be described later. Furthermore, in this embodiment, the voltage application unit 80 is also electrically connected to the third electrode 41 and the fourth electrode 42 of the second electrode unit 40, which will be described later. Hereinafter, the first electrode unit 30 and the second electrode unit 40 will not be distinguished separately and will simply be referred to as electrode unit 20. In this embodiment, each electrode unit 20 is electrically connected in parallel with each other.

[0035] The voltage application unit 80 applies an AC voltage of a predetermined driving frequency f0 to each electrode of each electrode unit 20. In this embodiment, the voltage application unit 80 is configured as a high-frequency power supply including a high-frequency voltage generation circuit, and has a crystal oscillator (not shown), a PLL (Phase Locked Loop) circuit, and a power amplifier. In other embodiments, the voltage application unit 80 may, for example, be configured as an inverter with a switching circuit having switching elements such as transistors. One of the potentials applied to the first electrode 31 and the second electrode 32 may also be a reference potential. Similarly, one of the potentials applied to the third electrode 41 and the fourth electrode 42 of the second electrode unit 40 may also be a reference potential.

[0036] In this embodiment, a high-frequency voltage is applied to each electrode of each electrode unit 20. In this specification, "high frequency" refers to a frequency of 1 MHz or higher. More specifically, in this embodiment, 13.56 MHz, one of the Industrial Scientific and Medical Band (ISM) frequencies, is used as the driving frequency f0. Furthermore, since the dielectric loss tangent of water reaches its maximum around 20 GHz, applying a high-frequency voltage of 2.45 GHz or 5.8 GHz in the ISM band to each electrode of the electrode unit 20 allows for more efficient heating of the liquid adhering to the dielectric Md. On the other hand, from the viewpoint of heating ink, good heating efficiency can be obtained even when the driving frequency f0 is low, for example, 13.56 MHz or 40.68 MHz. This is because when the driving frequency f0 is 13.56 MHz or 40.68 MHz, the dielectric loss tangent of water in the ink is low, and Joule heating is easily generated by the pigment components in the ink acting as resistance.

[0037] The heating control unit 180, like the ejection control unit 250 described above, is composed of a computer. The heating control unit 180 controls the voltage application unit 80, the moving unit 130, and the second conveying unit 322.

[0038] In this embodiment, the heating control unit 180 independently adjusts the voltage applied to the first electrode unit 30 and the voltage applied to the second electrode unit 40 by controlling the voltage application unit 80. For example, the heating control unit 180 can independently adjust the voltage applied to each electrode unit 20 by individually adjusting the resistance value of a variable resistor (not shown) that is connected in series with the first electrode unit 30 and the second electrode unit 40. Thus, the heating control unit 180 can independently adjust the electric field strength formed by each electrode unit 20. For example, if the electric field strength formed by the first electrode unit 30 is stronger, the heating control unit 180 applies a larger voltage to the first electrode unit 30; if the electric field strength formed by the second electrode unit 40 is stronger, the heating control unit 180 applies a larger voltage to the second electrode unit 40.

[0039] As described above, the dielectric heating device 100 in this embodiment has a first electrode unit 30 and a second electrode unit 40 as electrode units 20. Both the first electrode unit 30 and the second electrode unit 40 are mounted on the carriage 120. More specifically, in this embodiment, the first electrode unit 30 and the second electrode unit 40 are mounted on the carriage 120 by supporting the substrate 110 on which the first electrode unit 30 and the second electrode unit 40 are fixed. The second electrode unit 40 is disposed on the +X direction side of the first electrode unit 30.

[0040] The moving part 130 reciprocates the carriage 120 along the scanning direction, thereby causing the first electrode unit 30 and the second electrode unit 40 to reciprocate at least on the medium Md. The scanning direction includes both a direction along one side of the same axis and its opposite direction, which is the X direction in this embodiment. The direction along one side of the scanning direction is also called the positive direction, and its opposite direction is also called the negative direction. In this embodiment, the positive direction of the scanning direction is the +X direction, and the negative direction of the scanning direction is the -X direction. The moving part 130 in this embodiment is configured as a conveyor belt mechanism having an annular belt 131 on which the carriage 120 is fixed, a pulley 132, and a drive part 133 composed of a motor or the like. In other embodiments, the moving part 130 may be configured, for example, as a ball screw mechanism. Hereinafter, the movement of the carriage 120 or the electrode unit 20 along the scanning direction will also be referred to as the scanning of the carriage 120 or the electrode unit 20.

[0041] Figure 3 This is a perspective view showing the schematic configuration of the electrode unit 20 in this embodiment. More specifically, Figure 3 The diagram shows a first electrode unit 30. The first electrode unit 30 includes a first electrode 31, a second electrode 32, and a first coil 34. The second electrode unit 40 includes a third electrode 41, a fourth electrode 42, and a second coil 44. In this embodiment, the first electrode unit 30 and the second electrode unit 40 are configured identically. More specifically, the first electrode 31 and the third electrode 41 are identically configured. Furthermore, the second electrode 32 and the fourth electrode 42 are identically configured. Additionally, the first coil 34 and the second coil 44 are identically configured. Hereinafter, the first coil 34 and the second coil 44 will not be distinguished separately and will simply be referred to as coils.

[0042] The first electrode 31 and the second electrode 32 are conductors, such as those formed of metals, alloys, or conductive oxides. The first electrode 31 and the second electrode 32 can be formed of the same material or different materials. The first electrode 31 and the second electrode 32 can be disposed on a substrate made of a material with a low dielectric loss tangent or low conductivity for the purpose of maintaining their orientation or strength, or they can be supported by other components.

[0043] The first electrode 31 and the second electrode 32 are positioned opposite the dielectric Md in the Z direction. More specifically, as... Figure 1As shown, in this embodiment, the first electrode 31 and the second electrode 32 are disposed above the dielectric Md. Therefore, in this embodiment, the lower surfaces of the first electrode 31 and the second electrode 32 are opposite to the upper surface of the dielectric Md. A substrate 110 is disposed between the dielectric Md and the first electrode 31 and the second electrode 32. The direction in which the dielectric Md is opposite to the first electrode 31 and the second electrode 32 is also referred to as the opposition direction.

[0044] The first electrode 31 and the second electrode 32 are arranged such that the shortest distance between them is less than 1 / 10 of the wavelength of the electromagnetic field output from the first electrode unit 30. In this embodiment, the first electrode 31 has a boat-shaped shape, with a long side along the Y direction and a short side along the X direction. The lower surface of the third electrode 31 has a curved shape that bulges towards the -Z direction. When viewed along the Z direction, the first electrode 31 has an elongated oval shape with the Y direction as its long side.

[0045] The second electrode 32 has a ring-shaped structure that is flat in both the X and Y directions and has an elongated oval shape with the Y direction as its longer side. The second electrode 32 is arranged to surround the first electrode 31 when viewed along the Z direction. In the case referred to as "the second electrode 32 is arranged to surround the first electrode 31 when viewed along the Z direction," it is sufficient that the second electrode 32 surrounds more than half of the circumference of the first electrode 31 when viewed along the Z direction; it is not necessary for the second electrode 32 to completely surround the circumference of the first electrode 31 without gaps. Therefore, in other embodiments, the second electrode 32 may, for example, have a so-called C-shaped or U-shaped shape when viewed along the Z direction. Additionally, the second electrode 32 may, for example, have a shape that is intermittently interrupted when viewed along the Z direction and surrounds the first electrode 31 as a whole. In this case, the second electrode 32 is configured to impart the same potential to each part of the second electrode 32 when an AC voltage is applied to both the first electrode 31 and the second electrode 32.

[0046] like Figure 1 and Figure 2 As shown, both the first electrode 31 and the second electrode 32 are fixed to a substrate 110, which is arranged parallel to the X and Y directions. More specifically, the first electrode 31 is arranged such that the central portion of its lower surface in both the X and Y directions contacts the upper surface of the substrate 110. The second electrode 32 is arranged such that its lower surface contacts the upper surface of the substrate 110. Therefore, in this embodiment, the central portion of the lower surface of the first electrode 31 and the lower surface of the second electrode 32 are arranged on the same plane. Furthermore, in this embodiment, the substrate 110 is configured to be shared by the first electrode unit 30 and the second electrode unit 40.

[0047] In this embodiment, the substrate 110 is formed of glass. The substrate 110 is used to suppress the adhesion of liquids such as ink applied to the dielectric Md to the first electrode 31 and the second electrode 32, or, when the dielectric Md is cloth, to suppress the adhesion of fibers from the dielectric Md to the first electrode 31 and the second electrode 32. Similarly, in this embodiment, the substrate 110 also suppresses the adhesion of liquids or fibers to the third electrode 41 and the fourth electrode 42 of the second electrode unit 40. In other embodiments, the substrate 110 may, for example, be formed of aluminum oxide.

[0048] return Figure 3 The following explanation is provided. In this embodiment, the first electrode 31 is electrically connected to the voltage application unit 80 via the wire 35, the first coil 34, and the inner conductor IC1 of the coaxial cable. The second electrode 32 is electrically connected to the voltage application unit 80 via the connecting member 33 disposed on the upper part of the second electrode 32, or the outer conductor of the coaxial cable (not shown).

[0049] By applying a driving frequency f to the first electrode 31 and the second electrode 32 O An alternating voltage is generated from the first electrode 31 and the second electrode 32, thereby generating a voltage with a frequency corresponding to the driving frequency f. O An electromagnetic field of a corresponding wavelength. The intensity of this electromagnetic field is very strong near the first electrode 31 and the second electrode 32, and very weak at a distance. In this specification, the electromagnetic field generated near the first electrode 31 and the second electrode 32 by applying an alternating voltage is also referred to as the "near field". The "near" of the first electrode 31 and the second electrode 32 refers to the range at a distance from the first electrode 31 and the second electrode 32 that is less than 1 / 2π of the wavelength of the generated electromagnetic field. The range farther than the "near" is also referred to as the "distant field". In addition, in this specification, the electromagnetic field generated at a distance from the first electrode 31 and the second electrode 32 by applying an alternating voltage is also referred to as the "far field". The far field is equivalent to the electromagnetic field used in communication based on ordinary communication antennas, etc.

[0050] As described above, the first electrode 31 and the second electrode 32 are arranged such that the shortest distance between them is less than 1 / 10 of the wavelength of the electromagnetic field. This allows the density of the electromagnetic field generated from the first electrode 31 and the second electrode 32 to attenuate near them. Therefore, by appropriately maintaining the distance between the medium Md and the first electrode 31 and the second electrode 32, the liquid attached to the medium Md can be effectively heated by the electric field generated near the first electrode 31 and the second electrode 32, and far-field radiation from the first electrode 31 and the second electrode 32 can be suppressed. In particular, in this embodiment, the second electrode 32 is arranged to surround the first electrode 31 when viewed along the Z direction, thus further suppressing far-field radiation from the first electrode 31 and the second electrode 32.

[0051] In this embodiment, one end of the first coil 34 is electrically connected in series with the first electrode 31 via a wire 35, and the other end is connected to... Figure 1 and Figure 2 The voltage application section 80 shown is electrically connected in series. In this embodiment, the first coil 34 is composed of a solenoid coil and is arranged with its length direction along the Z direction. The shape, length, cross-sectional area, number of turns, material, etc. of the first coil 34 are selected, for example, according to the driving frequency f0, in a way that achieves impedance matching between the first electrode unit 30 and the voltage application section 80. In other embodiments, one end of the first coil 34 may not be connected in series with the first electrode 31, but connected in series with the second electrode 32.

[0052] By applying an alternating voltage to the first electrode unit 30 via the voltage application unit 80, a high voltage is generated at one end of the first coil 34. This increases the strength of the electric field generated from the first electrode 31 and the second electrode 32. Furthermore, the first coil 34 is preferably configured such that the distance between one end of the first coil 34 and the first electrode 31 is as small as possible. If the distance between one end of the first coil 34 and the first electrode 31 is large, the high voltage generated at one end of the first coil 34 may generate an electric field between the first coil 34 and the first electrode 31, or between the wire 35 and the second electrode 32, that is not conducive to heating the dielectric Md, potentially reducing the effectiveness of increasing the strength of the electric field generated from the first electrode 31 and the second electrode 32. In contrast, by bringing the distance between one end of the first coil 34 and the first electrode 31 closer, the generation of such an unhelpful electric field for heating the dielectric Md can be suppressed, thus effectively increasing the strength of the electric field generated from the first electrode 31 and the second electrode 32. In addition, in other embodiments, the first electrode unit 30 may not have the first coil 34. For example, the first electrode 31 may be formed in a zigzag shape so that the first electrode 31 can perform the same function as the coil.

[0053] The heating control unit 180 described above performs heating control in at least one of the outgoing path and the return path of the first electrode unit 30. Heating control refers to the control of heating the medium Md while moving the first electrode unit 30 along the X direction, which is the scanning direction. The outgoing path refers to the path of the first electrode unit 30 in one direction toward the scanning direction. The second path refers to the path of the first electrode unit 30 in the opposite direction to the scanning direction. In this embodiment, the heating control unit 180 performs heating control in both the first path and the second path. Hereinafter, the heating control performed in the outgoing path will also be referred to as the first control, and the heating control performed in the return path will also be referred to as the second control.

[0054] Figure 4 This is an explanatory diagram showing the movement of the carriage 120 in this embodiment. Figure 4 The diagram schematically illustrates a first movement path Pt1 and a second movement path Pt2. The first movement path Pt1 represents the path of the carriage 120 during its reciprocating movement along the X direction. The second movement path Pt2 represents the path of the carriage 120's relative movement with respect to the medium Md along the Y direction. Figure 4 In the diagram, the second moving path Pt2 is represented as the path of the carriage 120 moving towards the +Y direction, but in reality, as described above, the medium Md is moved relative to the carriage 120 towards the -Y direction by the second conveying unit 322. Furthermore, in Figure 4 In this specification, the first moving path Pt1 and the second moving path Pt2 are represented as the moving paths of the central position Pc of the first electrode unit 30 mounted on the carriage 120 in the X and Y directions. More specifically, the central position Pc corresponds to the central position of the first electrode 31 in the X and Y directions. In this specification, the central position Pc is also referred to as the "position of carriage 120" or "carriage position".

[0055] like Figure 4 As shown, in this embodiment, the heating control unit 180 controls the second conveying unit 322 to alternately perform the aforementioned conveying operation and stationary operation. Furthermore, during a single stationary operation, the heating control unit 180 performs at least one of the first control and the second control. More specifically, in this embodiment, the heating control unit 180 performs only one of the first control and the second control during a single stationary operation, and alternates between performing the first control and the second control. Therefore, in this embodiment, the second moving path Pt2 has a path connecting the end of the outgoing path Pt1o of the first moving path Pt1 to the beginning of the loop Pt1r of the first moving path Pt1, and a path connecting the end of the loop Pt1r to the beginning of the outgoing path Pt1o. In this embodiment, the outgoing path Pt1o is a path from end Ed1 on the -X direction side of the first moving path Pt1 to end Ed2 on the +X direction side. The loop Pt1r is a path from end Ed2 to end Ed1. The length of each second moving path Pt2 is equal to the conveying distance dc.

[0056] Figure 4 The diagram shows the first location P1, the second location P2, and the third location P3 along the X-direction movement path of the first electrode unit 30, specifically on the first movement path Pt1. Additionally, Figure 4The diagram shows a fourth location P4 on the movement path of the second electrode unit 40 (not shown) along the X direction. The first location P1 is where, when viewed along the Z direction, it overlaps with one end ME1 of the medium Md in the X direction. That is, when the first electrode unit 30 is located at the first location P1, it can also be said that the central position Pc of the first electrode unit 30 overlaps with one end ME1. The second location P2 is where, when viewed along the Z direction, it overlaps with the central portion MC of the medium Md in the X direction. The third location P3 and the fourth location P4 are where, when viewed along the Z direction, they overlap with the other end ME2 of the medium Md in the X direction. In this embodiment, when the first electrode unit 30 is located at the third location P3, the second electrode unit 40 is located at the fourth location P4. Furthermore, when the first electrode unit 30 is located at the first location P1, the second electrode unit 40 is located at location Pi, which overlaps with the other end ME2. Moreover, the phrase "the second electrode unit 40 is located at a certain location" means that the central position of the second electrode unit 40 in both the X and Y directions is located at that location.

[0057] like Figure 4 As shown, one end ME1 of medium Md is located further outward in the X direction than the central portion MC, and includes one end ME1p of medium Md in the X direction. When viewed along the Z direction, one end ME1 overlaps with the second movement path Pt2. More specifically, when viewed along the Z direction, one end ME1 overlaps with the path in the second movement path Pt2 that connects the end point of loop Pt1r and the start point of the destination path Pt1o. The central portion MC includes the central point MCp of medium Md in the X direction. In this embodiment, the second location P2 corresponds to the central point MCp. The other end ME2 of medium Md is located further outward in the X direction than the central portion MC, and includes another end ME2p of medium Md in the X direction. In this embodiment, when viewed along the Z direction, the other end ME2 overlaps with the path in the second movement path Pt2 that connects the end point of the destination path Pt1o and the start point of loop Pt1r. In this embodiment, one end ME1p is located further towards the -X direction side than the other end ME2p. Furthermore, in this embodiment, the width in the X direction of each of the end ME1, the other end ME2, and the central portion MC is defined as the width that is the same as the distance between the -X direction end of the second electrode 32 of the first electrode unit 30 and the +X direction end of the fourth electrode 42 of the second electrode unit 40. In other embodiments, as long as one end ME1 and the other end ME2 are located outside the central portion MC in the X direction, the width in the X direction of each of the end ME1 or the other end ME2 and the central portion MC is not particularly limited.

[0058] like Figure 4As shown, in this embodiment, the first location P1 is located outside the movement range Rg2 in the X direction of the second electrode unit 40. Furthermore, the fourth location P4 is located outside the movement range Rg1 in the X direction of the first electrode unit 30.

[0059] Figure 5 This is an explanatory diagram showing the heating region Rh of the first electrode unit 30 in this embodiment. Figure 5 In the diagram, the heating region Rh is marked with a shading line depicting the dot pattern. The heating region Rh refers to the area on the medium Md heated by the first electrode unit 30 during a single stationary operation. The heating region Rh is a strip-shaped area along the X direction depicted by the movement of the area Rs on the medium Md heated by the stationary first electrode unit 30 as the carriage 120 scans when viewed along the Z direction. In this embodiment, the area Rs corresponds to the portion located between the first electrode 31 and the second electrode 32 when viewed along the Z direction. This "portion between the first electrode 31 and the second electrode 32" includes the portion where the first electrode 31 or the second electrode 32 is disposed. In this embodiment, the shape or configuration of the first electrode unit 30 and the transport distance dc are set such that the length Lh of the heating region Rh in the X direction is an integer multiple of the transport distance dc. More specifically, in this embodiment, the length Lh is twice the transport distance dc. In this embodiment, the length Lh is approximately the same as the external dimensions of the second electrode 32 in the X direction.

[0060] Figure 6 This is an explanatory diagram showing the relationship between the carriage position and the electric field strength of the electrode unit 20 in the heating control performed in this embodiment. Figure 7 This is an explanatory diagram showing the relationship between the position of the carriage and the moving speed of the carriage 120 in the heating control performed in this embodiment. Figure 6 It is a graph in which the horizontal axis is set to the position of the first moving path Pt1 of the first electrode unit 30, and the vertical axis is set to the electric field strength. Figure 6 The horizontal axis represents the position coordinate of the first electrode unit 30 when the position coordinate of the end Ed1 of the first moving path Pt1 is set to zero. Figure 6 A larger value on the horizontal axis means that the first electrode unit 30, when viewed from end Ed1, is located closer to the +X direction side. Figure 6 In the diagram, the solid line represents the electric field strength formed through the first electrode unit 30, and the dashed line represents the electric field strength formed through the second electrode unit 40. Figure 7 This is a graph where the horizontal axis is set to the position of the first electrode unit 30 along its moving path Pt, and the vertical axis is set to the magnitude of the moving speed of the carriage 120. The moving speed of the carriage 120 at a given time point is equal to the moving speed of the first electrode unit 30 and the moving speed of the second electrode unit 40 at that time point. Figure 6and Figure 7 The coordinates p1 of the first location P1, p2 of the second location P2, p3 of the third location P3, and pE2 of the end Ed2 are shown respectively. In this embodiment, Figure 6 and Figure 7 The relationships shown also apply to both the first control and the second control.

[0061] In the heating control, when the first electrode unit 30 is located at the first location P1, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a first electric field strength E1. When the first electrode unit 30 is located at the second location P2, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a second electric field strength E2, which is stronger than the first electric field strength E1. Additionally, as... Figure 7 As shown, the heating control unit 180 controls the movement speed v1 of the carriage 120 at the first location P1 to be slower than the movement speed v2 at the second location P2. In other embodiments, the first movement speed may also be zero.

[0062] Furthermore, in this embodiment, during heating control, when the first electrode unit 30 is located at the first location P1, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a third electric field strength E3; when the first electrode unit 30 is located at the second location P2, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a fourth electric field strength E4, which is stronger than the third electric field strength E3. For example... Figure 5 As shown, in this embodiment, the first electric field strength E1 is stronger than the third electric field strength E3. Furthermore, in this embodiment, the second electric field strength E2 is the same as the fourth electric field strength E4. Additionally, the third electric field strength E3 may be zero. Furthermore, in other embodiments, the first electric field strength E1 may not be stronger than the third electric field strength E3; in this case, the first electric field strength E1 may also be zero.

[0063] In addition, such as Figure 6 As shown, in this embodiment, during heating control, when the first electrode unit 30 is located at a third location P3 overlapping with the other end ME2, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a fifth electric field strength E5, which is weaker than the second electric field strength E2. Furthermore, during heating control, when the first electrode unit 30 is located at the third location P3, that is, when the second electrode unit 40 is located at the fourth location P4, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a sixth electric field strength E6, which is weaker than the fourth electric field strength E4. The sixth electric field strength E6 is stronger than the fifth electric field strength E5. Additionally, as... Figure 7As shown, the heating control unit 180 controls the movement speed v3 of the carriage 120 at the third location P3 to be slower than the movement speed v2. The fifth electric field strength E5 and the movement speed v3 can also be zero. Furthermore, in other embodiments, the sixth electric field strength E6 may not be stronger than the fifth electric field strength E5; in this case, the sixth electric field strength E6 can also be zero.

[0064] According to the dielectric heating device 100 in the first embodiment described above, in the heating control, when the first electrode unit 30 is located at a first location P1 overlapping with one end ME1 of the dielectric Md, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a first electric field strength E1. When the carriage 120 is located at a second location P2 overlapping with the central portion MC of the dielectric Md, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a second electric field strength E2 that is stronger than the first electric field strength E1, and makes the moving speed v1 of the first electrode unit 30 at the first location P1 slower than the moving speed v2 of the first electrode unit 30 at the second location P2. This further reduces the difference in heating amount of the dielectric Md near the first location P1, where the first electrode unit 30 moves slower and has a longer dwell time, compared to the difference in heating amount of the dielectric Md at the second location P2, where the first electrode unit 30 moves faster and has a shorter dwell time. Therefore, it is possible to suppress deviation of the heating amount of the dielectric Md in the scanning direction.

[0065] Furthermore, in this embodiment, during heating control, when the first electrode unit 30 is located at a third location P3 overlapping with the other end ME2, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a fifth electric field strength E5, which is weaker than the second electric field strength E2. This causes the moving speed v3 of the first electrode unit 30 at the third location P3 to be slower than the moving speed v2 of the first electrode unit 30 at the second location P2. Therefore, it is possible to further suppress the deviation of the heating amount of the medium Md in the scanning direction.

[0066] Furthermore, in this embodiment, the second electrode 32 is configured to surround the first electrode 31 when viewed along the Z direction, and the first electrode unit 30 has a first coil 34 electrically connected in series with either the first electrode 31 or the second electrode 32. In this manner, the intensity of the electric field generated between the first electrode 31 and the second electrode 32, which contributes to the heating of the dielectric Md, can be effectively increased. Therefore, the dielectric Md can be heated more efficiently by the first electrode unit 30.

[0067] Furthermore, in this embodiment, the carriage 120 is also equipped with a second electrode unit 40 having a third electrode 41 and a fourth electrode 42, and the first electrode unit 30 and the second electrode unit 40 are arranged along the X direction. Therefore, the medium Md can be dried efficiently by means of the first electrode unit 30 and the second electrode unit 40.

[0068] Furthermore, in this embodiment, during heating control, when the first electrode unit 30 is located at the first location P1, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a third electric field strength E3; when the first electrode unit 30 is located at the second location P2, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a fourth electric field strength E4, which is stronger than the third electric field strength E3. Therefore, in the configuration with the second electrode unit 40, deviations in the heating amount of the medium Md in the scanning direction can be further suppressed.

[0069] Furthermore, in this embodiment, the first location P1 is located outside the movement range Rg2 of the second electrode unit 40 in the X direction. The second electrode unit 40 is located at location Pi on the medium Md when the first electrode unit 30 is located at the first location P1. In the heating control, when the first electrode unit 30 is located at the first location P1, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a third electric field strength E3. The first electric field strength E1 is stronger than the third electric field strength E3. In this manner, insufficient heating of the medium Md near the first location P1, which is difficult to be heated by the second electrode unit 40, can be suppressed. Therefore, it is possible to further suppress the deviation of the heating amount of the medium Md in the scanning direction.

[0070] Furthermore, in this embodiment, when the first electrode unit 30 is located at the third location P3, the second electrode unit 40 is located on the medium Md at a fourth location P4, which is further outward than the movement range Rg1 of the first electrode unit 30. Moreover, in the heating control, when the first electrode unit 30 is located at the third location P3, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a sixth electric field strength E6, which is stronger than the fifth electric field strength E5. This suppresses insufficient heating of the medium Md near the fourth location P4, where it is difficult for the first electrode unit 30 to heat. Therefore, it further suppresses deviations in the heating amount of the medium Md in the scanning direction.

[0071] Furthermore, in this embodiment, a conveying unit 320 is provided to convey the medium Md in the -Y direction. The heating control unit 180 of the conveying unit 320 alternately performs a conveying operation that conveys the medium Md for a predetermined conveying distance dc and a stationary operation that does not convey the medium Md and keeps it stationary, and performs heating control during the stationary operation. The length Lh in the Y direction of the heating region Rh on the medium Md, which is heated by the first electrode unit 30 during one stationary operation, is an integer multiple of the conveying distance dc. Therefore, it is possible to suppress deviations in the heating amount of the medium Md in the conveying direction. In addition, by setting the length Lh to more than twice the conveying distance dc, the same portion of the medium Md in the conveying direction can be heated more than twice by one electrode unit 20, which can reduce the heating amount of the medium Md in each heating control. Therefore, for example, it is possible to reduce the maximum voltage applied to the electrode unit 20. In addition, it is possible to prevent the medium Md from becoming too hot. In particular, when the airflow generating section 140 is provided as in this embodiment, by appropriately cooling the medium Md through the airflow generating section 140 during repeated heating control, it is possible to more effectively suppress the medium Md from becoming too hot.

[0072] B. Second implementation method:

[0073] Figure 8 This is an explanatory diagram illustrating the movement of the carriage 120 in the second embodiment. In this embodiment, unlike the first embodiment, the heating control unit 180 reciprocates the first electrode unit 30 along the scanning direction during a single stationary operation, performing first control and second control. The components of the dielectric heating device 100 and the liquid ejection system 200 in the second embodiment, unless otherwise specified, are the same as in the first embodiment.

[0074] Figure 8 As described in the first embodiment Figure 4 Similarly, the first movement path Pt1 and the second movement path Pt2b are shown. (As follows) Figure 8 As shown, in this embodiment, the heating control unit 180 performs one first control and one second control during each of the periods of a stationary operation. That is, during each stationary operation, the first electrode unit 30 and the second electrode unit 40 reciprocate once together with the carriage 120. Furthermore, heating control is performed in both the outgoing path and the return path. Therefore, in this embodiment, the second moving path Pt2b is formed only by the path connecting the end of the outgoing path Pt1o of the first moving path Pt1 and the return path Pt1r of the first moving path Pt1. Furthermore, in Figure 8 In the diagram, to make the technology easier to understand, the outgoing path Pt1o and the return path Pt1r are shown offset in the Y direction, but in reality, the outgoing path Pt1o and the return path Pt1r overlap.

[0075] According to the second embodiment described above, during a single stationary operation, the heating control unit 180 reciprocates the first electrode unit 30 along the X direction, performing first and second control. Therefore, for example, even if the length Lh is not set to more than twice the conveying distance dc as described in the first embodiment, the same portion of the medium Md can be heated more than twice by a single electrode unit 20, reducing the amount of medium Md heated in each heating control. Thus, for example, the maximum voltage applied to the electrode unit 20 can be reduced. Furthermore, it is possible to prevent the medium Md from becoming excessively hot. In particular, when the airflow generating unit 140 is provided as in this embodiment, by appropriately cooling the medium Md through the airflow generating unit 140 during repeated heating control, it is possible to more effectively prevent the medium Md from becoming excessively hot. Furthermore, by setting the length Lh to more than twice the conveying distance dc, the above-mentioned effects can be further improved.

[0076] In addition, in other embodiments, the heating control unit 180 may perform the first control or the second control more than twice during a single static operation.

[0077] C. Third implementation method:

[0078] Figure 9 This is a top view showing the general configuration of the liquid ejection system 200b in the third embodiment. In this embodiment, the liquid ejection device 205b is equipped with an electrode unit 20, and the liquid ejection device 205b also functions as a dielectric heating device 100b. In this embodiment, unlike the first embodiment, the carriage 120b also carries a liquid ejection section 210 in addition to the electrode unit 20. Therefore, the moving part 130 moves the carriage 120b back and forth, thereby causing the liquid ejection section 210 and the electrode unit 20 to move back and forth together at least on the medium Md. In addition, the liquid ejection system 200b in this embodiment differs from the first embodiment in that it has a cover 220, which will be described later. The parts of the configuration of the dielectric heating device 100b and the liquid ejection system 200b in the third embodiment that are not specifically described are the same as those in the first embodiment.

[0079] In this embodiment, the ejection control unit 250b also functions as the heating control unit 180. Furthermore, the conveying unit 320b does not have a first conveying unit 321 and a second conveying unit 322, but is configured as a conveying unit shared by the liquid ejection device 205b and the dielectric heating device 100b. In this embodiment, similar to the first or second embodiment, the ejection control unit 250b intermittently conveys the medium Md in the -Y direction via the conveying unit 320b.

[0080] like Figure 9As shown, the first electrode unit 30 and the liquid ejection portion 210 are arranged along the X direction. More specifically, in this embodiment, the first electrode unit 30, the liquid ejection portion 210, and the second electrode unit 40 are arranged in this order from the -X direction side to the +X direction side. That is, the liquid ejection portion 210 is sandwiched between the first electrode unit 30 and the second electrode unit 40 in the X direction. Therefore, in Figure 4 In the carriage 120 described above, either the first electrode unit 30 or the second electrode unit 40 is located behind the liquid ejection section 210 in both the outgoing path Pt1o and the return path Pt1r. Therefore, in both the outgoing path Pt1o and the return path Pt1r, liquid can be ejected onto the medium Md through the liquid ejection section 210, and the liquid ejected onto the medium Md can be heated by the electrode unit 20 located behind the liquid ejection section 210. Thus, liquid can be ejected onto the medium Md efficiently, and the liquid ejected onto the medium Md can be heated and dried more quickly.

[0081] like Figure 9 As shown, the cover 220 is positioned at the original position HP of the liquid ejection section 210. In this embodiment, the cover 220 has a rectangular plate-shaped bottom 221 and an edge 222, and has a concave shape opening in the +Z direction. The edge 222 is formed so as to be vertically erected from the four sides of the bottom 221. The bottom 221 is configured to move up and down via a cover moving mechanism (not shown). The cover moving mechanism may be, for example, a spring mechanism that operates in conjunction with the movement of the carriage 120b towards the original position HP, or a lifting device driven by a motor. A liquid-absorbing material, such as a hydrophilic foaming resin, may also be disposed inside the cover 220.

[0082] The original position HP is located on the -X direction side of the medium Md. Therefore, the cover 220 is located on the -X direction side of the medium Md. That is, the cover 220 is located further outward in the X direction than the medium Md. In this embodiment, the original position HP also serves as a maintenance position for maintaining the liquid ejection section 210.

[0083] Figure 10 This is an explanatory diagram of the sealing mechanism using cap 220. Cap 220 is configured to seal the liquid ejection section 210. Sealing refers to: such as Figure 10As shown, by covering at least a portion of the ejection surface 213 of the liquid ejection section 210 with the cover 220, a closed space CL is formed between the cover 220 and the ejection surface 213, forming a nozzle opening 211. More specifically, the cover 220 moves in the +Z direction toward the ejection surface 213 of the liquid ejection section 210, which is located at its original position HP, via the cover moving mechanism described above, and the upper end of the edge portion 222 is brought into close contact with the ejection surface 213, thereby forming the closed space CL. Hereinafter, the state in which the liquid ejection section 210 is covered is sometimes referred to as the covered state.

[0084] The capping is performed, for example, when the liquid ejection section 210 is not printing and is in standby mode. By capping, it is possible to prevent foreign matter from adhering to the ejection surface 213 and to prevent the liquid inside the nozzle of the liquid ejection section 210 from drying out. Sometimes, preventing the liquid inside the nozzle of the liquid ejection section 210 from drying out by capping is also referred to as "moisturizing". In the capped state, for example, by appropriately retaining moisture inside the cap 220, the moisturizing effect can be improved.

[0085] Furthermore, in this embodiment, the cover 220 functions as a drain receiving section for receiving liquid discharged from the liquid ejection section 210 during maintenance operations. More specifically, the cover 220, as a drain receiving section, stores the liquid discharged from the liquid ejection section 210 during the rinsing operation by sealing the liquid ejection section 210 which is currently performing a rinsing operation. The rinsing operation is not a printing operation that sprays liquid onto the medium Md for printing, but rather an operation performed to maintain the liquid ejection section 210. Moreover, by continuously spraying liquid from the liquid ejection section 210 at the maintenance position, it suppresses the occurrence of poor spraying due to the thickening of liquid in the nozzles or flow paths within the liquid ejection section 210.

[0086] Furthermore, in other embodiments, suction cleaning may be performed as a maintenance action. Suction cleaning refers to the following action: with the lid closed, a negative pressure is created in the enclosed space CL, thereby suctioning air bubbles or foreign matter contained in the liquid from the liquid ejection section 210 along with the liquid through the nozzle of the liquid ejection section 210. In this case, the liquid ejection section 210 may also be equipped with a suction pump or pipe for suctioning the liquid in the enclosed space CL.

[0087] Figure 11 This is an explanatory diagram showing the positional relationship between the first electrode unit 30 and the cover 220. Figure 11 In the diagram, the portion of cover 220 that overlaps with substrate 110 or electrode unit 20 when viewed along the Z-direction is indicated by dashed lines. For example... Figure 11As shown, in this embodiment, the end of the first electrode unit 30's movement range Rg1 on the -X direction side is located further on the -X direction side than the end ME1p of the medium Md. In this embodiment, the cover 220 is configured such that at least a portion of it can be located between the first electrode 31 and the second electrode 32 when viewed along the Z direction. In this "partial portion between the first electrode 31 and the second electrode 32", ... Figure 5 The description also includes portions provided with the first electrode 31 or the second electrode 32. In this embodiment, for example, as... Figure 11 As shown, when the liquid ejection section 210 is located at the fifth location P5, overlapping with one end ME1, the first electrode unit 30 is located at the sixth location P6, which is further towards the -X direction than one end ME1p. When viewed along the Z direction, at least a portion of the cover 220 is located between the first electrode 31 and the second electrode 32 of the first electrode unit 30, which is located at the sixth location P6.

[0088] Figure 12 This is an explanatory diagram showing the relationship between the position of the carriage 120 and the electric field strength of the electrode unit 20 in the heating control performed in this embodiment. Figure 12 This is consistent with the description in the first embodiment. Figure 6 Similarly, the horizontal axis is set to the position in the first moving path Pt1 of the carriage 120, and the vertical axis is set to a graph of electric field strength. In this embodiment, Figure 12 The relationship shown also applies to both the first and second controls. Figure 12 In addition to coordinates p1, p2, and pE2, the coordinates p6 of the sixth location P6 are also shown. In this embodiment, during heating control, when the cover 220 is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction, the heating control unit 180 makes the electric field strength formed by the first electrode unit 30 weaker than the second electric field strength E2. For example, as... Figure 12 As shown, in the heating control, when the first electrode unit 30 is located at the sixth location P6, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a seventh electric field strength E7, which is weaker than the second electric field strength E2. Furthermore, in this embodiment, the seventh electric field strength E7 is weaker than the first electric field strength E1. The seventh electric field strength E7 can also be zero.

[0089] In other embodiments, even when the first electrode unit 30 is positioned on the -X direction side of the liquid ejection portion 210 in the same manner as in this embodiment, it is possible, for example, to position the original position HP closer to the -X direction side so that, during heating control, the cover 220 is not located between the first electrode 31 and the second electrode 32 when viewed along the Z direction. However, in this case, since the distance between one end ME1p and the original position HP becomes larger, the time required for the liquid ejection portion 210 to move between the original position HP and the region on the medium Md is further increased. In this embodiment, as described above, since the cover 220 is configured such that at least a portion of it is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction for a portion of the period during which heating control is performed, it is possible to position the original position HP closer to the medium Md.

[0090] According to the third embodiment described above, a cover 220 is provided, which is configured to form a closed space CL between itself and the ejection surface 213 by covering at least a portion of the ejection surface 213. A carriage 120b carries a liquid ejection portion 210. The first electrode unit 30 and the liquid ejection portion 210 are arranged along the X direction. The cover 220 is configured such that, when viewed along the Z direction, at least a portion of the cover 220 is located between the first electrode 31 and the second electrode 32. In heating control, when the cover 220 is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction, the heating control unit 180 makes the electric field strength formed by the first electrode unit 30 weaker than the second electric field strength E2. Therefore, in the manner in which the cover 220 is configured such that at least a portion of it can be located between the first electrode 31 and the second electrode 32 when viewed along the Z direction, it is possible to suppress the liquid adhering to the cover 220 from being heated by the first electrode unit 30, thereby preventing the liquid adhering to the cover 220 or the cover 220 from becoming excessively hot.

[0091] Furthermore, in this embodiment, a drain receiving section is provided to receive liquid discharged from the liquid ejection section 210 during maintenance operations. At least a portion of the drain receiving section is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction for a portion of the heating control period. During heating control, when at least a portion of the drain receiving section is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction, the heating control unit 180 makes the electric field strength formed by the first electrode unit 30 weaker than the second electric field strength E2. Therefore, in a manner where the drain receiving section is configured such that at least a portion of it can be located between the first electrode 31 and the second electrode 32 when viewed along the Z direction, it is possible to suppress the liquid adhering to the drain receiving section from being heated by the first electrode unit 30. Thus, it is possible to prevent the liquid adhering to the drain receiving section or the drain receiving section from becoming excessively hot.

[0092] In other embodiments, the original position HP and the maintenance position may be different locations, in which case the cover 220 and the drain receiving section may be independent components. For example, the cover 220 and the drain receiving section may be arranged along the X direction, or they may be arranged in the X direction such that the medium Md is sandwiched between the cover 220 and the drain receiving section. Alternatively, only either the cover 220 or the drain receiving section may be provided. The drain receiving section, which is separate from the cover 220, may be configured, for example, as a reservoir for storing liquid discharged from the liquid ejection section 210, or as a flow channel for receiving liquid discharged from the liquid ejection section 210 and guiding the received liquid to other reservoirs. Alternatively, for example, the cover 220 may be arranged in separate original position HP and maintenance position.

[0093] D: Other implementation methods:

[0094] (D-1) In the above embodiment, the heating control unit 180 performs heating control in both the outgoing path and the return path. Alternatively, the heating control unit 180 may perform heating control only in either the outgoing path or the return path. That is, it may perform only at least one of the first control and the second control. In this case, the heating control unit 180 may, for example, move the first electrode unit 30 along the outgoing path in the +X direction and heat the medium Md during a stationary operation, and move the first electrode unit 30 along the return path in the -X direction without heating the medium Md during a transport operation. Furthermore, the heating control unit 180 may, for example, heat the medium Md not only during a stationary operation but also during a transport operation via the electrode unit 20.

[0095] (D-2) In the above embodiment, the second electrode 32 is arranged to surround the first electrode 31 when viewed along the Z direction, but it may not be arranged to surround the first electrode 31. For example, the first electrode 31 and the second electrode 32 may also be arranged to be adjacent to each other when viewed along the Z direction. In this case, the shape of the first electrode 31 and the second electrode 32 can be arbitrary, and can be circular, oblong, rectangular, polygonal, etc. In addition, when viewed along the Z direction, the areas of the first electrode 31 and the second electrode 32 may be the same or different. Preferably, when viewed along the Z direction, the first electrode 31 and the second electrode 32 are arranged to not overlap each other. Similarly, the fourth electrode 42 may not be arranged to surround the third electrode 41.

[0096] (D-3) In the above embodiment, a first electrode unit 30 and a second electrode unit 40 are provided as electrode units 20, but for example, only the first electrode unit 30 may be provided. Alternatively, three or more electrode units 20, including the first electrode unit 30 and the second electrode unit 40, may be provided. Furthermore, the arrangement of each electrode unit 20 can be arbitrary.

[0097] (D-4) In the above embodiment, the first electric field strength E1 is stronger than the third electric field strength E3. Conversely, the first electric field strength E1 can be weaker than the third electric field strength E3, or it can be the same as the third electric field strength E3.

[0098] (D-5) In the above embodiment, the first location P1 is located outside the movement range Rg2 of the second electrode unit 40, but it can also be located inside the movement range Rg2.

[0099] (D-6) In the above embodiment, in the dielectric heating device 100, the heating control unit 180 intermittently delivers the medium Md by alternately performing delivery operation and stationary operation, but it may also deliver the medium Md continuously. For example, the heating control unit 180 may also continuously deliver the medium Md in the -X direction in the dielectric heating device 100 without stopping it midway.

[0100] (D-7) In the above embodiment, the dielectric heating device 100 conveys the medium Md via the conveying unit 320, but it is also possible to convey the medium Md without conveying it. For example, it can be configured to not only reciprocate the carriage 120 in the X direction, but also move the moving unit 130 in a cross direction intersecting the X direction. Such a moving unit 130 is, for example, configured as a dual-axis actuator that moves the carriage 120 in the X and Y directions. In this case, the heating control unit 180 can, for example, repeatedly perform operations to move the carriage 120 a predetermined distance relative to the medium Md in the +Y direction intersecting the X direction, and operations to move the carriage 120 relative to the medium Md in the +X or -X direction, thereby achieving the same movement path as the carriage 120 in the intermittent conveying described above.

[0101] (D-8) In the above embodiment, the first electrode 31 has a boat-shaped shape, but it may not have a boat-shaped shape; for example, it may have a flat plate shape or a rod shape. Furthermore, the first electrode 31 may not have an oblong shape when viewed along the Z-direction; for example, it may have a circular shape, a rectangular shape, or other polygonal shapes. Similarly, the third electrode 41 may not have a boat-shaped shape, and it may not have an oblong shape when viewed along the Z-direction.

[0102] (D-9) In the above embodiment, during heating control, when the first electrode unit 30 is located at the first location P1, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a third electric field strength E3. When the first electrode unit 30 is located at the second location P2, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a fourth electric field strength E4, which is stronger than the third electric field strength E3. Alternatively, during heating control, when the second electrode unit 40 is located at the fourth location P4, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to a sixth electric field strength E6, which is weaker than the fourth electric field strength E4. However, the heating control unit 180 may also choose not to control the electric field strength of the second electrode unit 40 in this way. For example, the heating control unit 180 may only perform the above-described actions during heating control: setting the electric field strength of the second electrode unit 40 to a fourth electric field strength E4 when the first electrode unit 30 is located at the second location P2, and setting the electric field strength of the second electrode unit 40 to a sixth electric field strength E6 when the second electrode unit 40 is located at the fourth location P4. Alternatively, for example, the heating control unit 180 may keep the electric field strength of the second electrode unit 40 constant regardless of the position of the first electrode unit 30 or the second electrode unit 40 in the X direction during heating control.

[0103] (D-10) In the above embodiment, during heating control, when the first electrode unit 30 is located at a third location P3 overlapping with the other end ME2, the heating control unit 180 sets the electric field strength formed by the first electrode unit 30 to a fifth electric field strength E5, which is weaker than the second electric field strength E2. Alternatively, if the heating control unit 180 executes setting the electric field strength formed by the first electrode unit 30 to a first electric field strength E1 and setting it to a second electric field strength E2 when the first electrode unit 30 is located at a second location P2, then the electric field strength of the first electrode unit 30 may not be controlled in this way.

[0104] (D-11) In the first and second embodiments described above, the medium Md is continuously conveyed from the liquid ejection device 205 to the dielectric heating device 100. In this case, where the medium Md is continuously conveyed from the liquid ejection device 205 to the dielectric heating device 100, the conveying unit 320 may, for example, only have a conveying unit shared by the dielectric heating device 100 and the liquid ejection device 205. Alternatively, the medium Md may not be continuously conveyed from the liquid ejection device 205 to the dielectric heating device 100. For example, after the medium Md, coated with liquid by the liquid ejection device 205, is temporarily wound into a roll, it may be moved to the dielectric heating device 100 by a robot or the like. In this case, in the dielectric heating device 100, for example, the medium Md can be conveyed and heated by the second conveying unit 322 or the like while the rolled-up medium Md is being unwound.

[0105] (D-12) In the above embodiment, a frequency of 13.56 MHz is used as the driving frequency f0. However, the driving frequency f0 may not be 13.56 MHz; for example, frequencies from other ISM bands such as 40.68 MHz, 2.45 GHz, and 5.8 GHz may be used. Furthermore, the driving frequency f0 only needs to be a frequency capable of heating the liquid attached to the medium Md by the electrode unit 20, and does not need to be high-frequency. In this case, the driving frequency f0 is preferably, for example, 100 kHz or higher and less than 1 MHz.

[0106] (D-13) In the above embodiment, the dielectric heating device 100 is assembled into the liquid ejection system 200. Alternatively, the dielectric heating device 100 may not be assembled into the liquid ejection system 200, for example, the dielectric heating device 100 may be used alone.

[0107] E. Example for reference:

[0108] (E-1) Figure 13 This is an explanatory diagram showing the relationship between the position of the carriage 120 and the moving speed of the carriage 120 during the heating of the medium Md by the electrode unit 20 in the reference example. Figure 13 Is with Figure 7 Similarly, the horizontal axis is set to the position of the first electrode unit 30 in the moving path Pt, and the vertical axis is set to the magnitude of the moving speed of the slide 120. Figure 13 The coordinates pC of the central point MCp and pE2 of the other end ME2p are shown. Figure 13 In the example, the heating control unit 180 controls the moving speed of the carriage 120 in a manner that makes the amount of electrical charge per unit area applied to the medium Md at one end ME1 through the first electrode unit 30 consistent with the amount of electrical charge per unit area applied to the medium Md at the center MC through the first electrode unit 30. Figure 13 In the example, in the heating control, the heating control unit 180 may either set the electric field strength formed by the first electrode unit 30 to be constant on the moving path Pt, or it may not set the electric field strength formed by the first electrode unit 30 to be constant on the moving path Pt. Instead, it controls both the electric field strength formed by the first electrode unit 30 and the moving speed of the carriage 120, thereby making the electrical charge in one end ME1 consistent with the electrical charge in the central part MC as described above.

[0109] F. Other methods:

[0110] This disclosure is not limited to the embodiments described above, and can be implemented in various ways without departing from its spirit. For example, this disclosure can also be implemented in the following ways. The technical features in the above embodiments corresponding to the technical features in the various methods described below can be appropriately replaced or combined in order to solve part or all of the problems of this disclosure, or to achieve part or all of the effects of this disclosure. In addition, as long as the technical feature is not described as an essential feature in this specification, the technical feature can be appropriately deleted.

[0111] (1) According to a first aspect of this disclosure, a dielectric heating device is provided. The dielectric heating device comprises: a first electrode unit having a first electrode and a second electrode facing a dielectric, and heating the dielectric by dielectric heating; a voltage application unit applying an alternating voltage to the first electrode and the second electrode; a carriage carrying the first electrode unit; a movement unit that reciprocates the first electrode unit along the scanning direction at least on the dielectric by reciprocating the carriage along the scanning direction; and a heating control unit controlling the voltage application unit and the movement unit. The heating control unit performs heating control in at least one of a path and a loop, the path being a path of the first electrode unit toward the scanning direction, and the loop being a path of the first electrode unit in the opposite direction, wherein the heating control refers to heating the dielectric while moving the first electrode unit along the scanning direction. In the heating control, when the first electrode unit is located at a first location overlapping one end of the scanning direction of the medium, the heating control unit sets the electric field strength formed by the first electrode unit to a first electric field strength. When the first electrode unit is located at a second location overlapping the center of the scanning direction of the medium, the heating control unit sets the electric field strength formed by the first electrode unit to a second electric field strength that is stronger than the first electric field strength. The heating control unit makes the moving speed of the first electrode unit at the first location slower than the moving speed of the first electrode unit at the second location.

[0112] In this manner, the difference in heating amount of the medium near the first location where the first electrode unit moves slower and has a longer dwell time can be further reduced compared to the difference in heating amount of the medium at the second location where the first electrode unit moves faster and has a shorter dwell time. Therefore, deviations in the heating amount of the medium in the scanning direction can be suppressed.

[0113] (2) In the above manner, the second electrode may also be configured such that it surrounds the first electrode when viewed along the opposing direction of the medium and the first electrode and the second electrode, and the first electrode unit has a coil electrically connected in series with the first electrode or the second electrode.

[0114] In this way, the intensity of the electric field generated between the first and second electrodes, which facilitates the heating of the medium, can be effectively increased. Therefore, the medium can be heated more efficiently through the first electrode unit.

[0115] (3) In the above method, the dielectric heating device may also be: the dielectric heating device includes a second electrode unit, the second electrode unit has a third electrode and a fourth electrode opposite to the medium, and the medium is heated by dielectric heating, the voltage application unit applies an AC voltage to the third electrode and the fourth electrode, the slide carries the second electrode unit, and the moving part moves the slide back and forth, thereby causing the second electrode unit and the first electrode unit to move back and forth together at least on the medium, and the first electrode unit and the second electrode unit are arranged along the scanning direction.

[0116] In this way, the medium can be dried efficiently through the first electrode unit and the second electrode unit.

[0117] (4) In the above method, it is also possible that: the first location is located outside the movement range of the second electrode unit in the scanning direction, the second electrode unit is located on the medium when the first electrode unit is located at the first location, and in the heating control, when the first electrode unit is located at the first location, the heating control unit sets the electric field strength formed by the second electrode unit as the third electric field strength, and the first electric field strength is stronger than the third electric field strength.

[0118] In this manner, insufficient heating of the medium near a first location that is difficult to heat by the second electrode unit can be suppressed. Therefore, deviations in the heating amount of the medium in the scanning direction can be further suppressed.

[0119] (5) In the above manner, the dielectric heating device may also include a conveying section that conveys the medium in a conveying direction intersecting the scanning direction, and the heating control section performs: controlling the conveying section; alternately performing a conveying operation and a stationary operation, wherein the conveying operation is an operation of conveying the medium by the conveying section to a predetermined conveying distance, and the stationary operation is an operation of stationary without conveying the medium; and performing the heating control during the execution of the stationary operation, wherein the length of the area on the medium heated by the first electrode unit during one execution of the stationary operation in the conveying direction is an integer multiple of the conveying distance.

[0120] In this way, deviations in the heating amount of the medium in the conveying direction can be suppressed.

[0121] (6) In the above manner, it is also possible that the heating control unit moves the first electrode unit back and forth along the scanning direction during one of the static operations, and performs the heating control in the path and the loop.

[0122] In this manner, the same portion of the medium can be heated more than twice using a single electrode unit, reducing the amount of medium heated in each heating cycle. Therefore, for example, the maximum voltage applied to the first electrode unit can be reduced. Furthermore, for example, it can prevent the medium from becoming excessively hot.

[0123] (7) According to a second aspect of the present disclosure, a liquid ejection system is provided. The liquid ejection system includes: a dielectric heating device of the above-described manner; a liquid ejection section having an ejection surface having a nozzle opening, from which liquid is ejected and coated onto the medium; and an ejection control section for controlling the liquid ejection section.

[0124] (8) In the second method described above, it is also possible that the carriage carries the liquid ejection part.

[0125] The moving part reciprocates the carriage, thereby causing the liquid ejection part and the first electrode unit to reciprocate together at least on the medium. The liquid ejection system also includes a cover, which is disposed in the scanning direction at a position further outward than the medium and is configured to form a closed space between itself and the ejection surface by covering at least a portion of the ejection surface. The first electrode unit and the liquid ejection part are arranged along the scanning direction. When viewed in an opposing direction opposite to the medium and the first and second electrodes, at least a portion of the cover can be located between the first and second electrodes. In the heating control, when at least a portion of the cover is located between the first and second electrodes when viewed in the opposing direction, the heating control unit makes the electric field strength formed by the first electrode unit weaker than the second electric field strength.

[0126] In this manner, when the cover is configured such that at least a portion of it can be located between the first electrode and the second electrode when viewed in the opposite direction, it is possible to suppress the liquid adhering to the cover from being heated by the first electrode unit, thereby preventing the liquid adhering to the cover or the cover from becoming too hot.

[0127] (9) In the second method described above, the liquid ejector is mounted on the carriage, and the moving part moves the carriage back and forth so that the liquid ejector and the first electrode unit move back and forth together at least on the medium. The liquid ejection system also includes a drain receiving part, which is arranged in the scanning direction at a position further outward than the medium and receives the liquid discharged from the liquid ejector during maintenance of the liquid ejector. The first electrode unit and the liquid ejector are arranged along the scanning direction. The drain receiving part is arranged such that at least a portion of the drain receiving part can be located between the first electrode and the second electrode when viewed along the opposing direction opposite to the medium and the first electrode and the second electrode. In the heating control, when the drain receiving part is located between the first electrode and the second electrode when viewed along the opposing direction, the heating control part makes the electric field strength formed by the first electrode unit weaker than the second electric field strength.

[0128] In this manner, when the drain receiving part is arranged such that at least a portion of it can be located between the first electrode and the second electrode when viewed in the opposite direction, it is possible to prevent the liquid adhering to the drain receiving part from being heated by the first electrode unit. Therefore, it is possible to prevent the liquid adhering to the drain receiving part or the drain receiving part from becoming too hot.

[0129] (10) According to a third aspect of the present disclosure, a liquid ejection device is provided, wherein a liquid heated by an electrode unit is applied to a medium, the electrode unit having a first electrode and a second electrode opposite to the medium and subjected to an alternating voltage, and mounted on a carriage configured to reciprocate along a scanning direction, wherein in heating control, a first electric field strength formed by the electrode unit when the electrode unit is located at a first location overlapping one end of the medium in the scanning direction is stronger than a second electric field strength formed by the electrode unit when the electrode unit is located at a second location overlapping the center portion of the medium in the scanning direction, and the moving speed of the electrode unit at the first location is slower than the moving speed of the electrode unit at the second location, wherein the heating control is performed on at least one of a path of the electrode unit toward the scanning direction and a loop of the electrode unit toward the opposite direction, and the medium is heated while the electrode unit and the carriage are moved together along the scanning direction. The liquid ejection device includes: a conveying section for conveying the medium in a direction intersecting the scanning direction, a liquid ejection section for ejecting and coating the liquid onto the medium, and a control section for controlling the conveying section and the liquid ejection section.

Claims

1. A dielectric heating device, characterized by, Possessing: a first electrode unit having a first electrode and a second electrode opposed to a medium, and heating the medium by a dielectric heating method; a voltage application section that applies an alternating voltage to the first electrode and the second electrode; a carriage that mounts the first electrode unit; a moving section that moves the first electrode unit at least on the medium in a scanning direction by reciprocally moving the carriage in the scanning direction; and a heating control section that controls the voltage application section and the moving section, the heating control section performs heating control in at least either of a forward path in which the first electrode unit moves in one direction of the scanning direction, and a return path in which the first electrode unit moves in the opposite direction of the one direction, the heating control being heating of the medium while moving the first electrode unit in the scanning direction, in the heating control, when the first electrode unit is positioned at a first position overlapping an end portion in the scanning direction of the medium, the heating control section sets an electric field intensity formed by the first electrode unit to a first electric field intensity, when the first electrode unit is positioned at a second position overlapping a central portion in the scanning direction of the medium, the heating control section sets an electric field intensity formed by the first electrode unit to a second electric field intensity stronger than the first electric field intensity, the heating control section makes the moving speed of the first electrode unit at the first position slower than the moving speed of the first electrode unit at the second position.

2. The dielectric heating apparatus according to claim 1, wherein the second electrode is disposed in a manner of surrounding the first electrode when viewed in an opposite direction of the medium opposite to the first electrode and the second electrode, the first electrode unit has a coil electrically connected in series with the first electrode or the second electrode.

3. The dielectric heating apparatus according to claim 1, wherein the dielectric heating apparatus possesses a second electrode unit having a third electrode and a fourth electrode opposed to the medium, and heating the medium by a dielectric heating method, the voltage application section applies an alternating voltage to the third electrode and the fourth electrode, the carriage mounts the second electrode unit, the moving section moves the second electrode unit together with the first electrode unit at least on the medium by reciprocally moving the carriage, the first electrode unit and the second electrode unit are arranged in the scanning direction.

4. The dielectric heating apparatus according to claim 3, wherein the first position is located outside a moving range of the second electrode unit in the scanning direction, the second electrode unit is located on the medium when the first electrode unit is positioned at the first position, in the heating control, when the first electrode unit is positioned at the first position, the heating control section sets an electric field intensity formed by the second electrode unit to a third electric field intensity, the first electric field intensity is stronger than the third electric field intensity.

5. The dielectric heating apparatus according to claim 1, wherein the dielectric heating apparatus comprises a conveyance section that conveys the medium in a conveyance direction intersecting the scan direction, the dielectric heating apparatus comprises a conveyance section that conveys the medium in a conveyance direction intersecting the scan direction, the heating control section controls the conveyance section, the heating control section alternately performs a conveyance operation and a stationary operation, the conveyance operation being an operation of conveying the medium by the conveyance section by a predetermined conveyance distance, the stationary operation being an operation of being stationary without conveying the medium, the heating control section performs the heating control during the stationary operation, a length of a region on the medium heated by the first electrode unit during a period in which the stationary operation is performed once in the conveyance direction is an integral multiple of the conveyance distance.

6. The dielectric heating apparatus according to claim 5, wherein the heating control section, during a period in which the stationary operation is performed once, moves the first electrode unit to and fro in the scan direction and performs the heating control in the forward direction and the return direction.

7. A liquid ejection system, comprising: comprises: the dielectric heating apparatus according to any one of claims 1 to 6; a liquid ejection section that has an ejection surface on which a nozzle opening is formed, ejects and applies a liquid from the nozzle opening to the medium; and a ejection control section that controls the liquid ejection section.

8. The liquid ejection system according to claim 7, wherein the carriage mounts the liquid ejection section, the moving section moves the liquid ejection section to and fro at least on the medium together with the first electrode unit by moving the carriage to and fro, the liquid ejection system further comprises a cover that is disposed at a position further outward than the medium in the scan direction and is configured to be capable of covering at least a part of the ejection surface to form a closed space between the ejection surface, the first electrode unit and the liquid ejection section are arranged in the scan direction, the cover is disposed in such a manner that at least a part of the cover is capable of being positioned between the first electrode and the second electrode when viewed in an opposing direction in which the medium opposes the first electrode and the second electrode, in the heating control, when at least a part of the cover is positioned between the first electrode and the second electrode when viewed in the opposing direction, the heating control section causes the first electrode unit to form an electric field having a strength weaker than the second electric field.

9. The liquid ejection system according to claim 7, wherein the carriage mounts the liquid ejection section, the moving section moves the liquid ejection section to and fro at least on the medium together with the first electrode unit by moving the carriage to and fro, the liquid ejection system further comprises a liquid discharge receiving section that is disposed at a position further outward than the medium in the scan direction and receives the liquid discharged from the liquid ejection section in a maintenance operation of the liquid ejection section, the first electrode unit and the liquid ejection section are arranged in the scan direction, The drain receiving portion is configured so that at least a part of the drain receiving portion is located between the first electrode and the second electrode when viewed in an opposing direction in which the medium opposes the first electrode and the second electrode, In the heating control, when the drain receiving portion is located between the first electrode and the second electrode when viewed in the opposing direction, the heating control portion makes the electric field intensity formed by the first electrode unit weaker than the second electric field intensity.

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