Dielectric heating device and liquid discharge system

Abstract

To provide a dielectric heating device having a carriage which suppresses variation in a heating amount in a direction of reciprocation of the carriage.SOLUTION: In a dielectric heating device, a heating control part for controlling a voltage application part for applying an AC voltage to a first electrode and a second electrode of a first electrode unit, and a moving part for reciprocating a carriage mounted with the first electrode unit executes heating control of heating a medium while moving the first electrode unit in a scanning direction in at least one of a going path where the first electrode unit goes in one direction of the scanning direction and a return path where the first electrode unit goes in a direction opposite to the one direction. The heating control part sets electric field intensity of the first electrode unit as first electric field intensity when the first electrode unit is positioned at a first point overlapping one end of the medium, sets the electric field intensity as second electric field intensity stronger than the first electric field intensity when the first electrode unit is positioned at a second point overlapping the central part of the medium, in the heating control, and sets moving speed of the first electrode unit at the first point to be lower than the moving speed at the second point.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a dielectric heating device and a liquid dispensing system. [Background technology]

[0002] Regarding the dielectric heating device, Patent Document 1 describes a drying means having multiple microwave radiating devices. This drying means is fixed to the inkjet printer body and has a length that allows the entire width of the printing area of ​​the printing material in the main scanning direction to be heated and dried. In the drying means, the multiple microwave radiating devices are lined up in the main scanning direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-37228 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the larger the width of the printing material to be heated, the larger the microwave irradiation device or the number of microwave irradiation devices must be, depending on the width. Therefore, it has been considered to suppress such an increase in size by mounting a dielectric heating device on a carriage configured to be able to move back and forth along the width direction. However, in this case, for example, a change in the moving speed or direction of the carriage can cause a variation in the amount of heat in the moving direction of the carriage. [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, a dielectric heating device is provided. The dielectric heating device includes a first electrode unit having a first electrode and a second electrode facing a medium and heating the medium by a dielectric heating method, a voltage application unit applying an AC voltage to the first electrode and the second electrode, a carriage carrying the first electrode unit, a moving unit moving the carriage back and forth along a scanning direction to move the first electrode unit back and forth at least on the medium along the scanning direction, and a heating control unit controlling the voltage application unit and the moving unit. The heating control unit performs heating control for heating the medium while moving the first electrode unit along the scanning direction, at least in one of an outward 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 a direction opposite to the one direction. In the heating control, 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 first point overlapping with one end of the media in the scanning direction, and sets the electric field strength formed by the first electrode unit to a second electric field strength stronger than the first electric field strength when the first electrode unit is located at a second point overlapping with the center of the media in the scanning direction, and makes the moving speed of the first electrode unit at the first point slower than the moving speed of the first electrode unit at the second point.

[0006] According to a second aspect of the present disclosure, there is provided a liquid ejection system comprising: the dielectric heating device of the above aspect; a liquid ejection unit having an ejection surface with nozzle openings formed therein and ejecting and applying liquid from the nozzle openings to the medium; and an ejection control unit controlling the liquid ejection unit. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a liquid ejection system according to a first embodiment. [Diagram 2] FIG. 1 is a top view showing a schematic configuration of a dielectric heating device in a first embodiment. [Diagram 3]FIG. 2 is a perspective view showing a schematic configuration of an electrode unit. [Figure 4] FIG. 4 is an explanatory diagram showing the movement of a carriage in the first embodiment. [Diagram 5] FIG. 4 is an explanatory diagram showing a heating region of the first electrode unit. [Figure 6] FIG. 4 is an explanatory diagram showing the relationship between the carriage position and the electric field intensity in the first embodiment. [Figure 7] FIG. 4 is an explanatory diagram showing the relationship between the carriage position and the moving speed in the first embodiment. [Figure 8] FIG. 10 is an explanatory diagram showing the movement of a carriage in the second embodiment. [Figure 9] FIG. 13 is a top view showing a schematic configuration of a liquid ejection system according to a third embodiment. [Figure 10] FIG. 13 is an explanatory diagram of capping with a cap. [Figure 11] FIG. 4 is an explanatory diagram showing the positional relationship between a first electrode unit and a cap. [Figure 12] 13 is an explanatory diagram showing the relationship between the carriage position and the electric field intensity in the third embodiment. [Figure 13] 10A and 10B are explanatory diagrams showing the relationship between the carriage position and the moving speed in a reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. First embodiment: FIG. 1 is a schematic diagram showing a schematic configuration of a liquid ejection system 200 as a first embodiment. In FIG. 1, arrows indicating mutually orthogonal X, Y, and Z directions are shown. The X and Y directions are parallel to a horizontal plane, and the Z direction is a direction along a vertical upward direction. The arrows indicating the X, Y, and Z directions are also shown in other figures as appropriate so that the illustrated directions correspond to those in FIG. 1. In the following description, when specifying the direction, the direction indicated by the arrow in each figure is indicated as "+" and the opposite direction is indicated as "-", and positive and negative signs are used in combination to indicate the direction. Hereinafter, the +Z direction is also referred to as "upper", and the -Z direction is also referred to as "lower". In addition, in this specification, orthogonal includes a range of 90°±10°.

[0009] The liquid ejection system 200 includes a dielectric heating device 100 having an electrode unit 20, and a liquid ejection device 205. The liquid ejection system 200 in this embodiment further includes a transport unit 320. In the liquid ejection system 200, while the transport unit 320 transports the medium Md, the liquid ejection device 205 ejects and applies liquid to the medium Md, and the electrode unit 20 of the dielectric heating device 100 heats and dries the liquid applied to the medium Md. It can also be said that the liquid ejection device 205 applies the liquid heated by the electrode unit 20 onto the medium Md. The electrode unit 20 is also called a heater.

[0010] As the medium Md, for example, paper, cloth, film, etc. are used. The cloth used as the medium Md is formed by weaving, for example, fibers such as cotton, hemp, polyester, silk, rayon, etc., or fibers blended with these. In this embodiment, a sheet-shaped cotton cloth is used as the medium Md. As the liquid applied to the medium Md, for example, various inks are used. In this embodiment, as the liquid, an aqueous ink containing water as a main component is used. In this specification, the main component of the liquid refers to a substance contained in the liquid whose mass fraction is 50% or more. In other embodiments, in addition to the ink, any liquid may be used as the liquid, such as various coloring materials, electrode materials, samples such as biological organic matter and inorganic matter, lubricating oil, resin liquid, etching liquid, etc.

[0011] The transport unit 320 transports the medium Md. In this embodiment, the transport unit 320 is configured as a roller mechanism that transports the medium Md by driving a roller 323. The transport unit 320 is provided in the liquid ejection device 205 and has a first transport unit 321 that transports the medium Md in the liquid ejection device 205, and a second transport unit 322 that is provided in the dielectric heating device 100 and transports the medium Md in the dielectric heating device 100. The first transport unit 321 and the second transport unit 322 each have a roller 323 and a drive unit (not shown) that is configured by a motor or the like for driving the roller 323. In other embodiments, the transport unit 320 may be configured as a belt mechanism that transports the medium Md by driving a belt, for example.

[0012] The first transport unit 321 is disposed at a position in the +Y direction of the second transport unit 322. In this embodiment, the first transport unit 321 and the second transport unit 322 perform intermittent transport to transport the sheet-shaped medium Md intermittently in the -Y direction. More specifically, the first transport unit 321 and the second transport unit 322 alternately repeat a transport operation in which the roller 323 is operated to transport the medium Md a predetermined transport distance in the -Y direction, and a rest operation in which the roller 323 is not operated, that is, the medium Md is stopped without being transported. The direction in which the medium Md is transported by the transport unit 320 is also referred to as the transport direction. The transport direction is a direction intersecting a scanning direction described later, and in this embodiment, it is the -Y direction.

[0013] In this embodiment, the liquid ejection device 205 is configured as an inkjet printer that performs printing by ejecting and applying ink as a liquid to the medium Md. Therefore, it can be said that the liquid ejection system 200 is configured as a printing system equipped with an inkjet printer. The liquid ejection device 205 has a liquid ejection unit 210 that ejects and applies liquid to the medium Md, an ejection control unit 250, and the first transport unit 321 described above.

[0014] The liquid ejection unit 210 is configured as, for example, a piezo-type or thermal-type liquid ejection head, and has one or more head chips (not shown). Each head chip has a nozzle surface 212 in which a nozzle opening 211, which is an opening of a nozzle that ejects liquid, is formed. Each nozzle surface 212 constitutes an ejection surface 213 of the liquid ejection unit 210. In other words, it can be said that the liquid ejection unit 210 has an ejection surface 213 in which the nozzle opening 211 is formed. The liquid ejection unit 210 ejects and applies ink as a liquid from the nozzle opening 211 to the medium Md. The colors of ink ejected from each head chip of the liquid ejection unit 210 may be the same or different. In addition, the liquid ejection unit 210 may be configured to be able to move back and forth relative to the medium Md in a direction perpendicular to the Z direction and intersecting the Y direction, or may be configured as a so-called line head in which the position is fixed without moving back and forth relative to the medium Md.

[0015] The ink used as the liquid in this embodiment is a pigment ink containing a resin. The resin contained in the ink has the effect of firmly fixing the pigment on the medium Md through itself. Such a resin is used in a state where, for example, a resin that is poorly soluble or insoluble in a solvent such as water is made into fine particles and dispersed in the solvent, that is, in an emulsion state or suspension state. Examples of such a resin include acrylic resin, styrene acrylic resin, fluorene resin, urethane resin, polyolefin resin, rosin-modified resin, terpene resin, polyester resin, polyamide resin, epoxy resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene vinyl acetate resin, etc. Two or more of these resins may be used in combination. Such a resin is also called a resin.

[0016] The discharge control unit 250 is configured by a computer including one or more processors, a storage device, and an input / output interface for inputting and outputting signals from and to the outside. The discharge control unit 250 in this embodiment controls the liquid discharge unit 210 and the first transport unit 321 to discharge and adhere liquid to the medium Md while transporting the medium Md in the -Y direction. More specifically, the discharge control unit 250 performs printing on the medium Md while repeating the discharge of liquid onto the medium Md during the stationary operation by the first transport unit 321 described above and the movement of the medium Md in the -Y direction by the transport operation by the first transport unit 321. In other embodiments, the discharge control unit 250 may be configured by, for example, a combination of multiple circuits.

[0017] FIG. 2 is a top view showing a schematic configuration of the dielectric heating device 100 in the first embodiment. As shown in FIG. 1 and FIG. 2, the dielectric heating device 100 includes an electrode unit 20 that heats the medium Md by a dielectric heating method, a voltage application unit 80 that applies an AC voltage to the electrode unit 20, a carriage 120 that carries the electrode unit 20, a moving unit 130 that moves the carriage 120 back and forth, a heating control unit 180, and the above-mentioned second conveying unit 322. In addition, the dielectric heating device 100 in this embodiment is provided with an airflow generating unit 140 for generating an airflow. The airflow generating unit 140 in this embodiment is configured as a blower that blows air toward the medium Md. The airflow generating unit 140 can, for example, promote drying of the medium Md or promote cooling of the medium Md as appropriate. Note that the carriage 120, the moving unit 130, and the airflow generating unit 140 are omitted in FIG. 1.

[0018] In the present embodiment, the dielectric heating device 100 transports the medium Md using the second transport unit 322, and moves the carriage 120 back and forth using the moving unit 130 to move the electrode unit 20 back and forth over the medium Md, while heating the medium Md with an AC electric field generated by the electrode unit 20, thereby heating and drying the medium Md. The phrase "heating the medium Md with an AC electric field" includes not only heating the medium Md itself with an AC electric field, but also heating any adhering matter such as a liquid or solid adhering to the medium Md with an AC electric field.

[0019] The voltage application section 80 is electrically connected to a first electrode 31 and a second electrode 32 of a first electrode unit 30, which will be described later. In this embodiment, the voltage application section 80 is also electrically connected to a third electrode 41 and a fourth electrode 42 of a 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 from each other and will simply be referred to as electrode units 20. In this embodiment, the electrode units 20 are electrically connected in parallel to each other.

[0020] The voltage application unit 80 applies a predetermined driving frequency f 0 An AC voltage of 100 V is applied. In this embodiment, the voltage application unit 80 is configured as a high-frequency power supply including a high-frequency voltage generating circuit, and has a crystal oscillator, a PLL (Phase Locked Loop) circuit, and a power amplifier, which are not shown. In other embodiments, the voltage application unit 80 may be configured as an inverter equipped with a switching circuit having a switching element such as a transistor. One of the potentials applied to the first electrode 31 and the second electrode 32 may 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 be a reference potential.

[0021] 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 more. More specifically, in this embodiment, a driving frequency f 0 As the driving frequency, 13.56 MHz, which is one of the Industrial Scientific and Medical (ISM) bands, is used. Since the dielectric loss tangent of water is maximum at around 20 GHz, the liquid attached to the medium Md can be heated more efficiently by 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. On the other hand, from the viewpoint of heating the ink, the driving frequency f 0 However, even if the driving frequency is relatively low, for example, 13.56 MHz or 40.68 MHz, good heating efficiency can be obtained. This is because 0 This is because when the frequency is 13.56 MHz or 40.68 MHz, the dielectric tangent of water in the ink is low, while Joule heat is easily generated due to the electrical resistance of the pigment components in the ink.

[0022] The heating control unit 180 is configured by a computer, similar to the above-mentioned discharge control unit 250. The heating control unit 180 controls the voltage application unit 80, the movement unit 130, and the second transport unit 322.

[0023] In this embodiment, the heating control unit 180 controls the voltage application unit 80 to individually adjust the voltage applied to the first electrode unit 30 and the voltage applied to the second electrode unit 40. The heating control unit 180 can individually adjust the voltage applied to each electrode unit 20, for example, by individually adjusting the resistance values ​​of variable resistors (not shown) electrically connected in series to the first electrode unit 30 and the second electrode unit 40. This allows the heating control unit 180 to individually adjust the electric field strength formed by each electrode unit 20. For example, when the electric field strength formed by the first electrode unit 30 is to be stronger, the heating control unit 180 increases the voltage applied to the first electrode unit 30, and when the electric field strength formed by the second electrode unit 40 is to be stronger, the heating control unit 180 increases the voltage applied to the second electrode unit 40.

[0024] As described above, the dielectric heating device 100 in this embodiment has the first electrode unit 30 and the second electrode unit 40 as the electrode unit 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 substrate 110 to which the first electrode unit 30 and the second electrode unit 40 are fixed is supported by the carriage 120, thereby causing the first electrode unit 30 and the second electrode unit 40 to be mounted on the carriage 120. The second electrode unit 40 is disposed on the +X direction side of the first electrode unit 30.

[0025] The moving unit 130 moves the carriage 120 back and forth along the scanning direction, thereby moving the first electrode unit 30 and the second electrode unit 40 back and forth at least on the medium Md. The scanning direction includes both one side direction and the opposite direction along the same axis, and is the X direction in this embodiment. The one side direction of the scanning direction is also called the positive direction, and the 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 unit 130 in this embodiment is configured as a belt mechanism having an endless belt 131 to which the carriage 120 is fixed, a pulley 132, and a driving unit 133 configured by a motor or the like. In other embodiments, the moving unit 130 may be configured by, for example, a ball screw mechanism. Hereinafter, the movement of the carriage 120 or the electrode unit 20 along the scanning direction is also called scanning of the carriage 120 or the electrode unit 20.

[0026] FIG. 3 is a perspective view showing a schematic configuration of the electrode unit 20 in this embodiment. More specifically, FIG. 3 shows the first electrode unit 30. The first electrode unit 30 has a first electrode 31, a second electrode 32, and a first coil 34. The second electrode unit 40 has 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 in the same manner. More specifically, the first electrode 31 and the third electrode 41 are configured in the same manner. Also, the second electrode 32 and the fourth electrode 42 are configured in the same manner. Also, the first coil 34 and the second coil 44 are configured in the same manner. Hereinafter, the first coil 34 and the second coil 44 are also simply referred to as coils without distinguishing between them.

[0027] The first electrode 31 and the second electrode 32 are conductors and are formed of, for example, a metal, an alloy, a conductive oxide, or the like. The first electrode 31 and the second electrode 32 may be formed of the same material or different materials. For example, the first electrode 31 and the second electrode 32 may be disposed on a substrate or the like formed of a material with low dielectric tangent or conductivity, or may be supported by another member, in order to maintain their posture and strength.

[0028] The first electrode 31 and the second electrode 32 face the media Md in the Z direction. More specifically, as shown in FIG. 1, in this embodiment, the first electrode 31 and the second electrode 32 are disposed above the media Md. Therefore, in this embodiment, the lower surfaces of the first electrode 31 and the second electrode 32 face the upper surface of the media Md. A substrate 110 is disposed between the media Md and the first electrode 31 and the second electrode 32. The direction in which the media Md faces the first electrode 31 and the second electrode 32 is also referred to as the facing direction.

[0029] The first electrode 31 and the second electrode 32 are arranged such that the shortest distance between the first electrode 31 and the second electrode 32 is equal to or less than one tenth of the wavelength of the electromagnetic field output from the first electrode unit 30. The first electrode 31 in this embodiment has a boat-like shape with a longitudinal direction along the Y direction and a transverse direction along the X direction. The lower surface of the first electrode 31 has a curved shape that is convex toward the -Z direction side. When viewed along the Z direction, the first electrode 31 has an elliptical shape with the Y direction as the longitudinal direction.

[0030] The second electrode 32 has an oval ring shape that is flat in the X and Y directions and has the Y direction as the longitudinal direction. The second electrode 32 is arranged so as to surround the periphery of the first electrode 31 when viewed along the Z direction. When it is said that "the second electrode 32 is arranged so as to surround the first electrode 31 when viewed along the Z direction", it is sufficient that the second electrode 32 is arranged so as to surround more than half of the periphery of the first electrode 31 as a whole when viewed along the Z direction, and it is not necessary for the second electrode 32 to surround the entire periphery of the first electrode 31 without any gaps. Therefore, in other embodiments, the second electrode 32 may have a so-called C-shaped or U-shaped shape when viewed along the Z direction, for example. In addition, the second electrode 32 may have a shape that surrounds the first electrode 31 as a whole while being intermittently interrupted when viewed along the Z direction, for example. In this case, the second electrode 32 is configured so that the same potential is applied to each part of the second electrode 32 when an AC voltage is applied to the first electrode 31 and the second electrode 32.

[0031] As shown in FIG. 1 and FIG. 2, the first electrode 31 and the second electrode 32 are both fixed on a substrate 110 arranged parallel to the X direction and the Y direction. More specifically, the first electrode 31 is arranged so that the center of the lower surface of the first electrode 31 in the X direction and the Y direction contacts the upper surface of the substrate 110. The second electrode 32 is arranged so that the lower surface of the second electrode 32 contacts the upper surface of the substrate 110. Therefore, in this embodiment, the center of the lower surface of the first electrode 31 and the lower surface of the second electrode 32 are arranged on the same plane. In this embodiment, the substrate 110 is provided in common to the first electrode unit 30 and the second electrode unit 40.

[0032] In this embodiment, the substrate 110 is made of glass. The substrate 110 prevents liquid such as ink applied to the medium Md from adhering to the first electrode 31 and the second electrode 32, and prevents fluff from adhering to the first electrode 31 and the second electrode 32 when the medium Md is a cloth. In this embodiment, the substrate 110 also prevents liquid and fluff from adhering to the third electrode 41 and the fourth electrode 42 of the second electrode unit 40, as described above. In other embodiments, the substrate 110 may be made of, for example, alumina.

[0033] Returning to Fig. 3, in this embodiment, the first electrode 31 is electrically connected to the voltage application unit 80 via the electric 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 a connection member 33 disposed on the upper portion of the second electrode 32, an outer conductor of the coaxial cable (not shown), and the like.

[0034] The first electrode 31 and the second electrode 32 are driven at a driving frequency f 0 By applying an AC voltage of a driving frequency f 0 An electromagnetic field having a wavelength according to the wavelength of the generated electromagnetic field is generated. The intensity of this electromagnetic field is very strong near the first electrode 31 and the second electrode 32, and very weak far away. In this specification, the electromagnetic field generated near the first electrode 31 and the second electrode 32 by the application of an AC voltage is also called a "near electromagnetic field". The "near" of the first electrode 31 and the second electrode 32 refers to a range in which the distance from the first electrode 31 and the second electrode 32 is 1 / 2π or less of the wavelength of the generated electromagnetic field. A range farther than the "near" is also called a "far" range. In this specification, the electromagnetic field generated far away from the first electrode 31 and the second electrode 32 by the application of an AC voltage is also called a "far electromagnetic field". The far electromagnetic field corresponds to an electromagnetic field used for communication by a general communication antenna or the like.

[0035] As described above, the first electrode 31 and the second electrode 32 are arranged so that the shortest distance between them is equal to or less than one tenth 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 be attenuated in the vicinity of the first electrode 31 and the second electrode 32. 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 efficiently heated by the electric field generated in the vicinity of the first electrode 31 and the second electrode 32, while suppressing radiation of the far electromagnetic field from the first electrode 31 and the second electrode 32. In particular, in this embodiment, the second electrode 32 is arranged so as to surround the first electrode 31 when viewed along the Z direction, so that radiation of the far electromagnetic field from the first electrode 31 and the second electrode 32 can be further suppressed.

[0036] In this embodiment, one end of the first coil 34 is electrically connected in series to the first electrode 31 via an electric wire 35, and the other end is electrically connected in series to the voltage application unit 80 shown in Figs. 1 and 2. In this embodiment, the first coil 34 is configured as a solenoid coil, and is disposed so that its length direction is along the Z direction. The shape, length, cross-sectional area, number of turns, material, etc. of the first coil 34 depend on, for example, the driving frequency f 0 Also, the impedance of the first electrode unit 30 is selected so as to achieve impedance matching between the first electrode unit 30 and the voltage application unit 80. In other embodiments, one end of the first coil 34 may be connected in series with the second electrode 32 instead of the first electrode 31.

[0037] When the voltage application unit 80 applies an AC voltage to the first electrode unit 30, a high voltage is generated at one end of the first coil 34. This can increase the intensity of the electric field generated from the first electrode 31 and the second electrode 32. The first coil 34 is preferably disposed so 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 electric wire 35 and the second electrode 32 that does not contribute to heating the medium Md, and the effect of increasing the intensity of the electric field generated from the first electrode 31 and the second electrode 32 may be reduced. In contrast, by shortening the distance between one end of the first coil 34 and the first electrode 31, the generation of such an electric field that does not contribute to heating the medium Md can be suppressed, and the intensity of the electric field generated from the first electrode 31 and the second electrode 32 can be effectively increased. In other embodiments, the first electrode unit 30 may not have the first coil 34, and for example, the first electrode 31 may be formed in a meandering shape so that the first electrode 31 functions similarly to a coil.

[0038] The above-mentioned heating control unit 180 executes heating control in at least one of the forward and backward paths of the first electrode unit 30. The heating control refers to control for heating the medium Md while moving the first electrode unit 30 along the X direction, which is the scanning direction. The forward path refers to a path along which the first electrode unit 30 moves in one direction of the scanning direction. The second path refers to a path along which the first electrode unit 30 moves in a direction opposite to the one direction of the scanning direction. In this embodiment, the heating control unit 180 executes heating control in both the first path and the second path. Hereinafter, the heating control executed in the forward path is also referred to as the first control, and the heating control executed in the backward path is also referred to as the second control.

[0039] FIG. 4 is an explanatory diagram showing the movement of the carriage 120 in this embodiment. In FIG. 4, a first movement path Pt1 and a second movement path Pt2 are shown in schematic form. The first movement path Pt1 represents a path of the carriage 120 in the reciprocating movement along the X direction. The second movement path Pt2 represents a path of the carriage 120 moving relative to the medium Md along the Y direction. In FIG. 4, the second movement path Pt2 is shown as a path of the carriage 120 moving in the +Y direction, but in reality, as described above, the second transport section 322 moves the medium Md in the -Y direction relative to the carriage 120. Also, in FIG. 4, the first movement path Pt1 and the second movement path Pt2 are shown as paths of the movement of the center position Pc in the X direction and the Y direction of the first electrode unit 30 mounted on the carriage 120. More specifically, the center position Pc corresponds to the center position in the X direction and the Y direction of the first electrode 31. In this specification, the central position Pc is also referred to as "the position of the carriage 120" or "the carriage position."

[0040] As shown in FIG. 4, the heating control unit 180 in this embodiment alternately executes the above-mentioned transport operation and stationary operation by controlling the second transport unit 322. The heating control unit 180 executes at least one of the first control and the second control while executing one stationary operation. More specifically, in this embodiment, the heating control unit 180 executes only one of the first control and the second control in one stationary operation, and executes the first control and the second control alternately. Therefore, in this embodiment, the second movement path Pt2 has a path that connects the end of the outgoing path Pt1o of the first movement path Pt1 to the start of the return path Pt1r of the first movement path Pt1, and a path that connects the end of the return path Pt1r to the start of the outgoing path Pt1o. In this embodiment, the outgoing path Pt1o is a path that goes from the end Ed1 on the -X direction side of the first movement path Pt1 to the end Ed2 on the +X direction side. The return path Pt1r is a path that runs from the end Ed2 to the end Ed1. The length of each second movement path Pt2 is equal to the transport distance dc.

[0041] FIG. 4 shows a first point P1, a second point P2, and a third point P3 on the movement path of the first electrode unit 30 along the X direction, that is, on the first movement path Pt1. FIG. 4 also shows a fourth point P4 on the movement path of the second electrode unit 40 (not shown) along the X direction. The first point P1 is a point that overlaps with one end ME1 in the X direction of the medium Md when viewed along the Z direction. In other words, when the first electrode unit 30 is located at the first point P1, it can also be said that the center position Pc of the first electrode unit 30 overlaps with one end ME1. The second point P2 is a point that overlaps with the center part MC in the X direction of the medium Md when viewed along the Z direction. The third point P3 and the fourth point P4 are points that overlap with the other end ME2 in the X direction of the medium Md when viewed along the Z direction. In this embodiment, when the first electrode unit 30 is located at the third point P3, the second electrode unit 40 is located at the fourth point P4. When the first electrode unit 30 is located at the first point P1, the second electrode unit 40 is located at a point Pi where it overlaps with the other end ME2. Note that when it is said that "the second electrode unit 40 is located at a certain point," it means that the center position of the second electrode unit 40 in the X and Y directions is located at that point.

[0042] As shown in FIG. 4, one end ME1 of the medium Md is located outside the center portion MC in the X direction and includes one end ME1p of the medium Md in the X direction. When viewed along the Z direction, the one end ME1 overlaps with the second movement path Pt2. More specifically, when viewed along the Z direction, the one end ME1 overlaps with a path of the second movement path Pt2 that connects the end point of the return path Pt1r and the start point of the outward path Pt1o. The center portion MC includes a center point MCp of the medium Md in the X direction. In this embodiment, the second point P2 corresponds to the center point MCp. The other end ME2 of the medium Md is located outside the center portion MC in the X direction and includes the other end ME2p of the medium Md in the X direction. In this embodiment, the other end ME2 overlaps with a path of the second movement path Pt2 that connects the end point of the outward path Pt1o and the start point of the return path Pt1r. In this embodiment, the one end ME1p is located on the -X direction side of the other end ME2p. In this embodiment, the width in the X direction of each of the one end ME1, the other end ME2, and the central portion MC is defined as a width that coincides with the distance between the end on the -X direction side of the second electrode 32 of the first electrode unit 30 and the end on the +X direction side of the fourth electrode 42 of the second electrode unit 40. Note that, in other embodiments, as long as the 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 one end ME1, the other end ME2, and the central portion MC is not particularly limited.

[0043] 4, in this embodiment, the first point P1 is located outside a movement range Rg2 in the X direction of the second electrode unit 40. Moreover, the fourth point P4 is located outside a movement range Rg1 in the X direction of the first electrode unit 30.

[0044] FIG. 5 is an explanatory diagram showing the heating region Rh of the first electrode unit 30 in this embodiment. In FIG. 5, the heating region Rh is hatched with a halftone dot pattern. The heating region Rh refers to a region on the medium Md that is heated by the first electrode unit 30 while one stationary operation is being performed. When viewed along the Z direction, the heating region Rh is a strip-shaped region along the X direction that is drawn by the region Rs on the medium Md that is heated by the stationary first electrode unit 30 moving with the scanning of the carriage 120. When viewed along the Z direction, the region Rs in this embodiment corresponds to a portion located between the first electrode 31 and the second electrode 32. This "portion between the first electrode 31 and the second electrode 32" includes the portion where the first electrode 31 and the second electrode 32 are provided. In this embodiment, the shape and arrangement of the first electrode unit 30 and the transport distance dc are set so 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 equal to the outer dimension of the second electrode 32 in the X direction.

[0045] FIG. 6 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 executed in this embodiment. FIG. 7 is an explanatory diagram showing the relationship between the carriage position and the moving speed of the carriage 120 in the heating control executed in this embodiment. FIG. 6 is a graph in which the horizontal axis represents the position of the first electrode unit 30 on the first moving path Pt1 and the vertical axis represents the electric field strength. The horizontal axis of FIG. 6 is expressed as 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. A larger value on the horizontal axis of FIG. 6 means that the first electrode unit 30 is located further toward the +X direction side as viewed from the end Ed1. In FIG. 6, the electric field strength formed by the first electrode unit 30 is shown by a solid line, and the electric field strength formed by the second electrode unit 40 is shown by a dashed line. FIG. 7 is a graph in which the horizontal axis represents the position of the first electrode unit 30 on the moving path Pt and the vertical axis represents the magnitude of the moving speed of the carriage 120. The moving speed of the carriage 120 at a certain point in time is equal to the moving speed of the first electrode unit 30 and the moving speed of the second electrode unit 40 at that point in time. Coordinates p1 of the first point P1, coordinates p2 of the second point P2, coordinates p3 of the third point P3, and coordinates pE2 of the end Ed2 are shown, respectively, in Fig. 6 and Fig. 7. In this embodiment, the relationships shown in Fig. 6 and Fig. 7 are similarly applied to both the first control and the second control.

[0046] In the heating control, when the first electrode unit 30 is located at a first point P1, the heating control unit 180 sets the electric field strength generated by the first electrode unit 30 to a first electric field strength E1, and when the first electrode unit 30 is located at a second point P2, the electric field strength generated by the first electrode unit 30 to a second electric field strength E2 that is stronger than the first electric field strength E1. Also, as shown in Fig. 7, in the heating control, the heating control unit 180 makes the moving speed v1 of the carriage 120 at the first point P1 slower than the moving speed v2 at the second point P2. In other embodiments, the first moving speed may be zero.

[0047] In the present embodiment, the heating control unit 180, in the heating control, when the first electrode unit 30 is located at the first point P1, sets the electric field intensity formed by the second electrode unit 40 to the third electric field intensity E3, and when the first electrode unit 30 is located at the second point P2, sets the electric field intensity formed by the second electrode unit 40 to the fourth electric field intensity E4, which is stronger than the third electric field intensity E3. As shown in FIG. 5, in the present embodiment, the first electric field intensity E1 is stronger than the third electric field intensity E3. Note that, in the present embodiment, the second electric field intensity E2 and the fourth electric field intensity E4 are the same. Also, the third electric field intensity E3 may be zero. Also, in other embodiments, the first electric field intensity E1 may not be stronger than the third electric field intensity E3, and in this case, the first electric field intensity E1 may be zero.

[0048] As shown in FIG. 6, in this embodiment, when the first electrode unit 30 is located at a third point P3 where the first electrode unit 30 overlaps with the other end ME2, the heating control unit 180 sets the electric field intensity formed by the first electrode unit 30 to a fifth electric field intensity E5 that is weaker than the second electric field intensity E2 in the heating control. When the first electrode unit 30 is located at the third point P3, that is, when the second electrode unit 40 is located at the fourth point P4, the heating control unit 180 sets the electric field intensity formed by the second electrode unit 40 to a sixth electric field intensity E6 that is weaker than the fourth electric field intensity E4 in the heating control. The sixth electric field intensity E6 is stronger than the fifth electric field intensity E5. As shown in FIG. 7, the heating control unit 180 sets the moving speed v3 of the carriage 120 at the third point P3 to be slower than the moving speed v2 in the heating control. The fifth electric field intensity E5 and the moving speed v3 may each be zero. In addition, in other embodiments, the sixth electric field strength E6 does not have to be stronger than the fifth electric field strength E5, in which case the sixth electric field strength E6 may be zero.

[0049] According to the dielectric heating device 100 in the first embodiment described above, in the heating control, the heating control unit 180 sets the electric field strength generated by the first electrode unit 30 to a first electric field strength E1 when the first electrode unit 30 is located at a first point P1 where the first electrode unit 30 overlaps with one end ME1 of the medium Md, sets the electric field strength generated by the first electrode unit 30 to a second electric field strength E2 that is stronger than the first electric field strength E1 when the carriage 120 is located at a second point P2 where the carriage 120 overlaps with the center portion MC of the medium Md, and makes the moving speed v1 of the first electrode unit 30 at the first point P1 slower than the moving speed v2 of the first electrode unit 30 at the second point P2. This makes it possible to reduce the difference between the amount of heat of the medium Md near the first point P1, where the moving speed of the first electrode unit 30 is slower and the staying time is longer, and the amount of heat of the medium Md at the second point P2, where the moving speed of the first electrode unit 30 is faster and the staying time is shorter. Therefore, it is possible to suppress variation in the amount of heat applied to the medium Md in the scanning direction.

[0050] In this embodiment, the heating control unit 180 further sets the electric field strength generated by the first electrode unit 30 to a fifth electric field strength E5 that is weaker than the second electric field strength E2 when the first electrode unit 30 is located at a third point P3 where the first electrode unit 30 overlaps with the other end ME2, and sets the moving speed v3 of the first electrode unit 30 at the third point P3 to be slower than the moving speed v2 of the first electrode unit 30 at the second point P2. This makes it possible to further suppress variations in the amount of heat applied to the medium Md in the scanning direction.

[0051] Furthermore, in this embodiment, the second electrode 32 is disposed so as 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 to the first electrode 31 or the second electrode 32. With this configuration, it is possible to effectively increase the strength of the electric field that is generated between the first electrode 31 and the second electrode 32 and contributes to heating the media Md. Therefore, the first electrode unit 30 can heat the media Md more efficiently.

[0052] In this embodiment, the carriage 120 further includes 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 side by side in the X direction. Therefore, the first electrode unit 30 and the second electrode unit 40 can efficiently dry the medium Md.

[0053] In this embodiment, further, in the heating control, the heating control unit 180 sets the electric field strength generated by the second electrode unit 40 to a third electric field strength E3 when the first electrode unit 30 is located at the first point P1, and sets the electric field strength generated by the second electrode unit 40 to a fourth electric field strength E4 that is stronger than the third electric field strength E3 when the first electrode unit 30 is located at the second point P2. Therefore, in a configuration including the second electrode unit 40, it is possible to further suppress the variation in the amount of heat of the medium Md in the scanning direction.

[0054] In this embodiment, the first point P1 is located outside the movement range Rg2 of the second electrode unit 40 in the X direction, and the second electrode unit 40 is located at a point Pi on the medium Md when the first electrode unit 30 is located at the first point P1, and the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 as the third electric field strength E3 when the first electrode unit 30 is located at the first point P1 in the heating control. The first electric field strength E1 is stronger than the third electric field strength E3. With this configuration, it is possible to prevent the amount of heat of the medium Md from being insufficient near the first point P1, which is difficult to heat by the second electrode unit 40. Therefore, it is possible to further prevent the amount of heat of the medium Md from varying in the scanning direction.

[0055] In this embodiment, when the first electrode unit 30 is located at the third point P3, the second electrode unit 40 is located at a fourth point P4 on the medium Md, which is outside the moving range Rg1 of the first electrode unit 30. Then, in the heating control, when the first electrode unit 30 is located at the third point P3, the heating control unit 180 sets the electric field intensity formed by the second electrode unit 40 to a sixth electric field intensity E6 that is stronger than the fifth electric field intensity E5. This makes it possible to prevent the amount of heat of the medium Md from being insufficient near the fourth point P4 that is difficult to heat by the first electrode unit 30. Therefore, it is possible to further prevent the amount of heat of the medium Md from varying in the scanning direction.

[0056] In this embodiment, the heating control unit 180 includes a transport unit 320 that transports the medium Md in the -Y direction, and controls the transport unit 320 to alternate between a transport operation that transports the medium Md a predetermined transport distance dc and a stationary operation that stops the medium Md without transporting it, and executes heating control while the stationary operation is being performed. The length Lh in the Y direction of the heating region Rh on the medium Md that is heated by the first electrode unit 30 while one stationary operation is being performed is an integer multiple of the transport distance dc. Therefore, it is possible to suppress variation in the amount of heat of the medium Md in the transport direction. Note that by making the length Lh twice or more the transport distance dc, the same portion of the medium Md in the transport direction can be heated two or more times by one electrode unit 20, and the amount of heat of the medium Md per heating control can be reduced. Therefore, for example, the maximum voltage applied to the electrode unit 20 can be lowered. It is also possible to suppress the medium Md from becoming too hot. In particular, when the airflow generating unit 140 is provided as in this embodiment, the airflow generating unit 140 can be used to appropriately cool the medium Md while the heating control is being repeated, thereby more effectively preventing the medium Md from becoming too hot.

[0057] B. Second embodiment: 8 is an explanatory diagram showing the movement of the carriage 120 in the second embodiment. In this embodiment, unlike the first embodiment, the heating control unit 180 moves the first electrode unit 30 back and forth along the scanning direction while performing one stationary operation, and executes the first control and the second control. Parts of the configuration of the dielectric heating device 100 and the liquid ejection system 200 in the second embodiment that are not particularly described are similar to those in the first embodiment.

[0058] FIG. 8 shows the first movement path Pt1 and the second movement path Pt2b, similarly to FIG. 4 described in the first embodiment. As shown in FIG. 8, in this embodiment, the heating control unit 180 executes the first control and the second control once each while performing one stilling operation. That is, while one stilling operation is being performed, the first electrode unit 30 and the second electrode unit 40 perform one reciprocating movement together with the carriage 120. Then, the heating control is executed in both the forward path and the return path. Therefore, in this embodiment, the second movement path Pt2b is composed only of a path that connects the end of the forward path Pt1o of the first movement path Pt1 and the return path Pt1r of the first movement path Pt1. Note that in FIG. 8, the forward path Pt1o and the return path Pt1r are illustrated shifted in the Y direction in order to facilitate understanding of the technology, but in reality, the forward path Pt1o and the return path Pt1r overlap.

[0059] According to the second embodiment described above, the heating control unit 180 moves the first electrode unit 30 back and forth along the X direction while performing one stationary operation, and executes the first control and the second control. As a result, for example, even if the length Lh is not set to be twice or more the transport distance dc as described in the first embodiment, the same part of the medium Md can be easily heated two or more times by one electrode unit 20, and the amount of heat of the medium Md per heating control can be reduced. Therefore, for example, the maximum voltage applied to the electrode unit 20 can be lowered. In addition, it is possible to prevent the medium Md from becoming too hot. In particular, when the airflow generating unit 140 is provided as in this embodiment, the airflow generating unit 140 can be used to appropriately cool the medium Md while the heating control is being repeated, thereby more effectively preventing the medium Md from becoming too hot. Note that the above effect can be further enhanced by setting the length Lh to be twice or more the transport distance dc.

[0060] In other embodiments, the heating control unit 180 may execute the first control or the second control two or more times while executing one stilling operation.

[0061] C. Third embodiment: FIG. 9 is a top view showing a schematic configuration of a liquid ejection system 200b in the third embodiment. In this embodiment, the electrode unit 20 and the like are incorporated in the liquid ejection device 205b, and the liquid ejection device 205b also functions as a dielectric heating device 100b. In this embodiment, the carriage 120b is equipped with a liquid ejection unit 210 in addition to the electrode unit 20, unlike the first embodiment. Therefore, the moving unit 130 moves the carriage 120b back and forth to move the liquid ejection unit 210 together with the electrode unit 20 back and forth at least on the medium Md. In addition, unlike the first embodiment, the liquid ejection system 200b in this embodiment includes a cap 220, which will be described later. Parts of the configuration of the dielectric heating device 100b and the liquid ejection system 200b in the third embodiment that are not particularly described are similar to those in the first embodiment.

[0062] In this embodiment, the discharge control unit 250b also functions as the heating control unit 180. Moreover, the transport unit 320b does not have the first transport unit 321 and the second transport unit 322, and is configured as a transport unit common to the liquid discharger 205b and the dielectric heating device 100b. In this embodiment, the discharge control unit 250b intermittently transports the medium Md in the -Y direction by the transport unit 320b, similar to the first and second embodiments.

[0063] As shown in FIG. 9, the first electrode unit 30 and the liquid discharger 210 are arranged side by side in the X direction. More specifically, in this embodiment, the first electrode unit 30, the liquid discharger 210, and the second electrode unit 40 are arranged side by side in this order from the -X direction side to the +X direction side. That is, the liquid discharger 210 is sandwiched between the first electrode unit 30 and the second electrode unit 40 in the X direction. As a result, either the first electrode unit 30 or the second electrode unit 40 is located behind the liquid discharger 210 in both the outgoing path Pt1o and the returning path Pt1r of the carriage 120 described in FIG. 4 and the like. Therefore, in both the outgoing path Pt1o and the returning path Pt1r, the liquid discharger 210 discharges liquid onto the medium Md, and the liquid discharged onto the medium Md can be heated by the electrode unit 20 located behind the liquid discharger 210. Therefore, the liquid can be efficiently ejected onto the medium Md, and the liquid ejected onto the medium Md can be heated and dried more quickly.

[0064] As shown in FIG. 9, the cap 220 is disposed at the home position HP of the liquid discharger 210. The cap 220 in this embodiment has a rectangular plate-shaped bottom 221 and edge portions 222 formed to stand vertically from the four sides of the bottom 221, and has a concave shape that opens toward the +Z direction. The bottom 221 is configured so that the cap 220 can be moved up and down by a cap moving mechanism (not shown). The cap moving mechanism is configured, for example, by a spring mechanism that operates in conjunction with the movement of the carriage 120b to the home position HP, or a lifting device that operates by driving a motor. A liquid absorbent material, for example, made of hydrophilic foamed resin, may be disposed inside the cap 220.

[0065] The home position HP is disposed on the -X direction side of the medium Md. As a result, the cap 220 is disposed on the -X direction side of the medium Md. In other words, the cap 220 is disposed on the outer side of the medium Md in the X direction. In this embodiment, the home position HP also serves as a maintenance position, which is a position for maintaining the liquid ejection unit 210.

[0066] FIG. 10 is an explanatory diagram of capping by the cap 220. The cap 220 is configured to be able to cap the liquid ejection unit 210. Capping refers to forming a closed space CL in which the nozzle opening 211 opens between the cap 220 and the ejection surface 213 by covering at least a part of the ejection surface 213 of the liquid ejection unit 210 as shown in FIG. 10. More specifically, the cap 220 moves in the +Z direction toward the ejection surface 213 of the liquid ejection unit 210 located at the home position HP by the above-mentioned cap moving mechanism, and forms the closed space CL by bringing the upper end of the edge portion 222 into close contact with the ejection surface 213. Hereinafter, the state in which the liquid ejection unit 210 is capped may also be referred to as a capping state.

[0067] Capping is performed, for example, when the liquid ejection unit 210 is on standby and not executing printing. Capping can prevent foreign matter from adhering to the ejection surface 213 and the liquid inside the nozzles of the liquid ejection unit 210 from drying. Preventing the liquid inside the nozzles of the liquid ejection unit 210 from drying by capping is sometimes called "moisturizing." In the capping state, for example, moisture can be appropriately maintained inside the cap 220, thereby enhancing the moisturizing effect.

[0068] Furthermore, the cap 220 in this embodiment functions as a drainage receiving portion that receives liquid discharged from the liquid discharger 210 during a maintenance operation of the liquid discharger 210. More specifically, the cap 220 as a drainage receiving portion caps the liquid discharger 210 that is performing a flushing operation, thereby storing the liquid discharged from the liquid discharger 210 during the flushing operation. The flushing operation is not a printing operation in which liquid is discharged onto the medium Md to perform printing, but an operation performed for the maintenance of the liquid discharger 210, and is an operation in which liquid is continuously discharged from the liquid discharger 210 at a maintenance position to suppress the occurrence of discharge defects due to increased viscosity of the liquid in the nozzles, flow paths, and the like in the liquid discharger 210.

[0069] In other embodiments, for example, suction cleaning may be performed as the maintenance operation. Suction cleaning refers to an operation in which, in the capping state, negative pressure is generated in the closed space CL, and air bubbles and foreign matter contained in the liquid are sucked from the liquid discharger 210 via the nozzle of the liquid discharger 210. In this case, the liquid discharger 210 may include a suction pump, a tube, or the like for sucking the liquid in the closed space CL.

[0070] FIG. 11 is an explanatory diagram showing the positional relationship between the first electrode unit 30 and the cap 220. In FIG. 11, the portion of the cap 220 that overlaps with the substrate 110 and the electrode unit 20 when viewed along the Z direction is indicated by a broken line. As shown in FIG. 11, in this embodiment, the end of the movement range Rg1 of the first electrode unit 30 on the -X direction side is located on the -X direction side of one end ME1p of the medium Md. In this embodiment, the cap 220 is arranged so that at least a part of it can be 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 and the second electrode 32 are provided, as described in FIG. 5. In this embodiment, for example, as shown in FIG. 11, when the liquid ejection section 210 is located at a fifth point P5 overlapping with one end ME1, the first electrode unit 30 is located at a sixth point P6 on the -X direction side of the one end ME1p, and when viewed along the Z direction, at least a part of the cap 220 is located between the first electrode 31 and the second electrode 32 of the first electrode unit 30 located at the sixth point P6.

[0071] FIG. 12 is an explanatory diagram showing the relationship between the position of the carriage 120 and the electric field intensity of the electrode unit 20 in the heating control executed in this embodiment. As in FIG. 6 described in the first embodiment, FIG. 12 is a graph in which the horizontal axis represents the position of the carriage 120 in the first movement path Pt1 and the vertical axis represents the electric field intensity. In this embodiment, the relationship shown in FIG. 12 is similarly applied to both the first control and the second control. In FIG. 12, in addition to the coordinates p1, p2, and pE2, the coordinate p6 of the sixth point P6 is shown. In this embodiment, the heating control unit 180 weakens the electric field intensity formed by the first electrode unit 30 compared to the second electric field intensity E2 in the heating control when the cap 220 is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction. 12, in the heating control, when the first electrode unit 30 is located at a sixth point P6, the heating control unit 180 sets the electric field intensity generated by the first electrode unit 30 to a seventh electric field intensity E7 that is weaker than the second electric field intensity E2. In this embodiment, the seventh electric field intensity E7 is weaker than the first electric field intensity E1. The seventh electric field intensity E7 may be zero.

[0072] In another embodiment, even if the first electrode unit 30 is disposed on the -X direction side of the liquid discharger 210 as in the present embodiment, for example, by disposing the home position HP further on the -X direction side, it is possible to prevent the cap 220 from being positioned between the first electrode 31 and the second electrode 32 when viewed along the Z direction during heating control. However, in this case, the distance between the one end ME1p and the home position HP becomes larger, so that the time required for the liquid discharger 210 to move between the home position HP and the area on the medium Md increases. In the present embodiment, as described above, the cap 220 is disposed so that at least a part of it is positioned between the first electrode 31 and the second electrode 32 when viewed along the Z direction during a part of the period during which the heating control is being performed, so that the home position HP can be disposed closer to the medium Md.

[0073] According to the third embodiment described above, the carriage 120b is provided with a cap 220 configured to be able to form a closed space CL between the ejection surface 213 by covering at least a portion of the ejection surface 213, the carriage 120b carries the liquid ejection section 210, the first electrode unit 30 and the liquid ejection section 210 are arranged side by side in the X direction, the cap 220 is arranged such that at least a portion of the cap 220 is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction, and in heating control, the heating control section 180 weakens the electric field strength formed by the first electrode unit 30 compared to the second electric field strength E2 when the cap 220 is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction. Therefore, when the cap 220 is arranged such that at least a portion of it can be positioned between the first electrode 31 and the second electrode 32 when viewed along the Z direction, the liquid adhering to the cap 220 can be prevented from being heated by the first electrode unit 30, and the liquid adhering to the cap 220 and the cap 220 can be prevented from becoming too hot.

[0074] In addition, in this embodiment, a drainage receiver is provided for receiving liquid discharged from the liquid discharger 210 during the maintenance operation of the liquid discharger 210, and at least a part of the drainage receiver is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction during a part of the period during which the heating control is being performed, and the heating control unit 180 weakens the electric field strength formed by the first electrode unit 30 compared to the second electric field strength E2 when at least a part of the drainage receiver is located between the first electrode 31 and the second electrode 32 when viewed along the Z direction during the heating control. Therefore, in a form in which the drainage receiver is arranged so that at least a part 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 prevent the liquid adhering to the drainage receiver from being heated by the first electrode unit 30, and therefore it is possible to prevent the liquid adhering to the drainage receiver and the drainage receiver from becoming too hot.

[0075] In another embodiment, the home position HP and the maintenance position may be different positions, and in this case, the cap 220 and the drainage receiving portion may be separate from each other. In this case, for example, the cap 220 and the drainage receiving portion may be arranged side by side in the X direction, or the medium Md may be arranged so as to be sandwiched between the cap 220 and the drainage receiving portion in the X direction. Also, only one of the cap 220 and the drainage receiving portion may be provided. The drainage receiving portion provided separately from the cap 220 may be configured, for example, as a storage portion that stores the liquid discharged from the liquid discharge portion 210, or may be configured as a flow path that receives the liquid discharged from the liquid discharge portion 210 and guides the received liquid to another storage portion. Also, for example, the cap 220 may be provided at each of the home position HP and the maintenance position that are separated from each other.

[0076] D. Other embodiments: (D-1) In the above embodiment, the heating control unit 180 executes the heating control in both the forward path and the return path. In contrast, the heating control unit 180 may execute the heating control only in either the forward path or the return path. That is, at least one of the first control and the second control may be executed. In this case, the heating control unit 180 may heat the medium Md while moving the first electrode unit 30 in the +X direction along the forward path during the stationary operation, and may move the first electrode unit 30 in the -X direction along the return path without heating the medium Md during the transport operation. In addition, the heating control unit 180 may heat the medium Md by the electrode unit 20 not only during the stationary operation but also during the transport operation.

[0077] (D-2) In the above embodiment, the second electrode 32 is arranged so as to surround the first electrode 31 when viewed along the Z direction, but it does not have to be arranged so as to surround the first electrode 31. For example, the first electrode 31 and the second electrode 32 may be arranged so as to be adjacent to each other when viewed along the Z direction. In this case, the shapes of the first electrode 31 and the second electrode 32 may be any shape, and may be a circle, an oval, a rectangle, a polygon, or the like. In addition, the areas of the first electrode 31 and the second electrode 32 may be the same or different from each other when viewed along the Z direction. It is preferable that the first electrode 31 and the second electrode 32 are arranged so as not to overlap each other when viewed along the Z direction. Similarly, the fourth electrode 42 does not have to be arranged so as to surround the third electrode 41.

[0078] (D-3) In the above embodiment, the first electrode unit 30 and the second electrode unit 40 are provided as the electrode unit 20, but for example, only the first electrode unit 30 may be provided. Furthermore, 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 the electrode units 20 may be arbitrary.

[0079] (D-4) In the above embodiment, the first electric field strength E1 is stronger than the third electric field strength E3. In contrast, the first electric field strength E1 may be weaker than the third electric field strength E3 or may be the same as the third electric field strength E3.

[0080] (D-5) In the above embodiment, the first point P1 is located outside the movement range Rg2 of the second electrode unit 40, but it may be located inside the movement range Rg2.

[0081] (D-6) In the above embodiment, in the dielectric heating device 100, the heating control unit 180 intermittently transports the medium Md by alternately performing a transport operation and a stationary operation, but the medium Md does not have to be transported intermittently. For example, in the dielectric heating device 100, the heating control unit 180 may continuously transport the medium Md in the -X direction without stopping it midway.

[0082] (D-7) In the above embodiment, in the dielectric heating device 100, the medium Md is transported by the transport unit 320, but the medium Md does not have to be transported. For example, the moving unit 130 may be configured to not only move the carriage 120 back and forth in the X direction, but also to move the carriage 120 along a cross direction that crosses the X direction. Such a moving unit 130 is configured, for example, by a two-axis actuator that moves the carriage 120 in the X direction and the Y direction. In this case, the heating control unit 180 may realize a movement path similar to the movement path of the carriage 120 in the intermittent transport described above, for example, by repeating an operation of moving the carriage 120 a predetermined distance in the +Y direction that crosses the X direction relative to the medium Md, and an operation of moving the carriage 120 in the +X direction and the -X direction relative to the medium Md.

[0083] (D-8) In the above embodiment, the first electrode 31 has a boat-like shape, but it does not have to have a boat-like shape, and may have, for example, a flat plate shape or a rod shape. Furthermore, the first electrode 31 does not have to have an elliptical shape when viewed along the Z direction, and may have, for example, a circular shape, a rectangular shape, or another polygonal shape. Similarly, the third electrode 41 does not have to have a boat-like shape, and it does not have to have an elliptical shape when viewed along the Z direction.

[0084] (D-9) In the above embodiment, in the heating control, when the first electrode unit 30 is located at the first point P1, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to the third electric field strength E3, and when the first electrode unit 30 is located at the second point P2, the electric field strength formed by the second electrode unit 40 to the fourth electric field strength E4 that is stronger than the third electric field strength E3. Also, in the heating control, when the second electrode unit 40 is located at the fourth point P4, the heating control unit 180 sets the electric field strength formed by the second electrode unit 40 to the sixth electric field strength E6 that is weaker than the fourth electric field strength E4. In contrast, the heating control unit 180 does not have to control the electric field strength of the second electrode unit 40 in this way. For example, in the heating control, the heating control unit 180 may only execute the following among the above: setting the electric field intensity formed by the second electrode unit 40 to the fourth electric field intensity E4 when the first electrode unit 30 is located at the second point P2, and setting the electric field intensity formed by the second electrode unit 40 to the sixth electric field intensity E6 when the second electrode unit 40 is located at the fourth point P4. Also, for example, in the heating control, the heating control unit 180 may keep the electric field intensity of the second electrode unit 40 constant regardless of the positions of the first electrode unit 30 and the second electrode unit 40 in the X direction.

[0085] (D-10) In the above embodiment, when the first electrode unit 30 is located at a third point P3 where it overlaps with the other end ME2, the heating control unit 180 sets the electric field strength generated by the first electrode unit 30 to a fifth electric field strength E5 that is weaker than the second electric field strength E2 in the heating control. In contrast, if the heating control unit 180 executes the heating control such that the electric field strength generated by the first electrode unit 30 is set to the first electric field strength E1, and the heating control unit 180 executes the heating control such that the electric field strength is set to the second electric field strength E2 when the first electrode unit 30 is located at the second point P2, then it is not necessary to control the electric field strength of the first electrode unit 30 in this manner.

[0086] (D-11) In the first and second embodiments, the medium Md is continuously transported from the liquid ejection device 205 to the dielectric heating device 100. When the medium Md is continuously transported from the liquid ejection device 205 to the dielectric heating device 100 in this manner, the transport unit 320 may, for example, only have a transport unit common to the dielectric heating device 100 and the liquid ejection device 205. The medium Md does not have to be continuously transported from the liquid ejection device 205 to the dielectric heating device 100. For example, the medium Md to which the liquid has been applied by the liquid ejection device 205 may be once wound into a roll, and then the medium Md 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 wound into a roll can be unwound while the medium Md is transported by the second transport unit 322 or the like and heated.

[0087] (D-12) In the above embodiment, the driving frequency f 0 A frequency of 13.56 MHz is used as the driving frequency f 0 The frequency of 13.56 MHz may not be used as the driving frequency f, and other frequencies such as 40.68 MHz, 2.45 GHz, and 5.8 GHz, which are in other ISM bands, may be used. 0 The driving frequency f does not have to be a high frequency as long as it is a frequency that can heat the liquid attached to the medium Md by the electrode unit 20. In this case, 0 It is preferable that the frequency be, for example, 100 kHz or more and less than 1 MHz.

[0088] (D-13) In the above embodiment, the dielectric heating device 100 is incorporated into the liquid ejection system 200. In contrast, the dielectric heating device 100 does not have to be incorporated into the liquid ejection system 200, and for example, only the dielectric heating device 100 may be used alone.

[0089] E.Reference example: (E-1) FIG. 13 is an explanatory diagram showing the relationship between the position of the carriage 120 and the movement speed of the carriage 120 while the medium Md is being heated by the electrode unit 20 in a reference example. Like FIG. 7, FIG. 13 is a graph in which the horizontal axis represents the position of the first electrode unit 30 on the movement path Pt and the vertical axis represents the magnitude of the movement speed of the carriage 120. FIG. 13 shows the coordinate pC of the center point MCp and the coordinate pE2 of the other end ME2p. In the example of FIG. 13, the heating control unit 180 controls the movement speed of the carriage 120 in the heating control so that the amount of power per unit area applied to the medium Md by the first electrode unit 30 at one end ME1 of the medium Md matches the amount of power per unit area applied to the medium Md by the first electrode unit 30 at the center MC of the medium Md. In the example of Figure 13, in the heating control, the heating control unit 180 may, for example, keep the electric field strength formed by the first electrode unit 30 constant along the movement path Pt, or may not keep the electric field strength formed by the first electrode unit 30 constant along the movement path Pt, and may control both the electric field strength formed by the first electrode unit 30 and the movement speed of the carriage 120 to match the amount of power at one end ME1 and the amount of power at the central portion MC, as described above.

[0090] F. Other forms: The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various forms without departing from the spirit of the present disclosure. For example, the present disclosure can be realized in the following forms. The technical features in the above-mentioned embodiments corresponding to the technical features in each form described below can be appropriately replaced or combined in order to solve some or all of the problems of the present disclosure, or to achieve some or all of the effects of the present disclosure. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0091] (1) According to a first aspect of the present disclosure, there is provided a dielectric heating device. The dielectric heating device includes a first electrode unit having a first electrode and a second electrode facing a medium and heating the medium by a dielectric heating method, a voltage application unit applying an AC voltage to the first electrode and the second electrode, a carriage carrying the first electrode unit, a moving unit moving the carriage back and forth along a scanning direction to move the first electrode unit back and forth at least on the medium along the scanning direction, and a heating control unit controlling the voltage application unit and the moving unit. The heating control unit performs heating control for heating the medium while moving the first electrode unit along the scanning direction, at least in one of an outward 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 a direction opposite to the one direction. In the heating control, 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 first point overlapping with one end of the media in the scanning direction, and sets the electric field strength formed by the first electrode unit to a second electric field strength stronger than the first electric field strength when the first electrode unit is located at a second point overlapping with the center of the media in the scanning direction, and makes the moving speed of the first electrode unit at the first point slower than the moving speed of the first electrode unit at the second point. According to this embodiment, it is possible to reduce the difference between the amount of heat applied to the medium near the first point where the first electrode unit moves slower and stays there longer, and the amount of heat applied to the medium near the second point where the first electrode unit moves faster and stays there shorter, thereby suppressing variation in the amount of heat applied to the medium in the scanning direction.

[0092] (2) In the above embodiment, the second electrode may be disposed so as to surround the first electrode when viewed along the opposing direction in which the media faces the first electrode and the second electrode, and the first electrode unit may have a coil electrically connected in series to the first electrode or the second electrode. According to this embodiment, it is possible to effectively increase the strength of the electric field that is generated between the first electrode and the second electrode and contributes to heating the media. Therefore, the first electrode unit can heat the media more efficiently.

[0093] (3) In the above embodiment, a second electrode unit may be provided that has a third electrode and a fourth electrode facing the medium and heats the medium by a dielectric heating method, the voltage application unit applies an AC voltage to the third electrode and the fourth electrode, the carriage carries the second electrode unit, the movement unit moves the carriage back and forth to move the second electrode unit together with the first electrode unit at least over the medium, and the first electrode unit and the second electrode unit may be arranged side by side in the scanning direction. According to this embodiment, the medium can be efficiently dried by the first electrode unit and the second electrode unit.

[0094] (4) In the above embodiment, the first point may be located outside a moving range of the second electrode unit in the scanning direction, the second electrode unit may be located on the media when the first electrode unit is located at the first point, and the heating control unit may set the electric field strength formed by the second electrode unit to a third electric field strength when the first electrode unit is located at the first point, and the first electric field strength may be stronger than the third electric field strength in the heating control. According to this embodiment, it is possible to prevent the amount of heating of the media from being insufficient near the first point that is difficult to heat by the second electrode unit. Therefore, it is possible to further prevent the amount of heating of the media from varying in the scanning direction.

[0095] (5) In the above embodiment, a transport unit is provided that transports the medium in a transport direction intersecting the scanning direction, and the heating control unit controls the transport unit to alternately perform a transport operation in which the transport unit transports the medium a predetermined transport distance and a stationary operation in which the medium is stationary without being transported, and executes the heating control while the stationary operation is being performed, and the length in the transport direction of an area on the medium that is heated by the first electrode unit while one stationary operation is being performed may be an integer multiple of the transport distance. According to this embodiment, it is possible to suppress variation in the amount of heating of the medium in the transport direction.

[0096] (6) In the above embodiment, the heating control unit may move the first electrode unit back and forth along the scanning direction while performing one of the stationary operations, and perform the heating control on the outward path and the return path. According to this embodiment, the same part of the media can be easily heated two or more times by one electrode unit, and the amount of heat applied to the media per heating control can be reduced. Therefore, for example, the maximum voltage applied to the first electrode unit can be reduced. Also, for example, the media can be prevented from becoming too hot.

[0097] (7) According to a second aspect of the present disclosure, there is provided a liquid ejection system comprising: the dielectric heating device of the above aspect; a liquid ejection unit having an ejection surface with nozzle openings formed therein and ejecting liquid from the nozzle openings to apply the liquid to the medium; and an ejection control unit controlling the liquid ejection unit.

[0098] (8) In the second embodiment, the carriage carries the liquid ejection unit, and the moving unit moves the carriage back and forth to move the liquid ejection unit together with the first electrode unit at least over the medium, and further includes a cap that is arranged outside the medium in the scanning direction and configured to cover at least a portion of the ejection surface to form a closed space in which the nozzle opening opens between the ejection surface, the first electrode unit and the liquid ejection unit are arranged side by side in the scanning direction, and the cap is arranged so that at least a portion of the cap is positioned between the first electrode and the second electrode when viewed along an opposing direction in which the medium, the first electrode, and the second electrode are opposed to each other, and the heating control unit, in the heating control, may weaken the electric field strength formed by the first electrode unit compared to the second electric field strength when at least a portion of the cap is positioned between the first electrode and the second electrode when viewed along the opposing direction. According to this configuration, when the cap is positioned such that at least a portion of it can be positioned between the first electrode and the second electrode when viewed along the opposing direction, the liquid adhering to the cap can be prevented from being heated by the first electrode unit, thereby preventing the liquid adhering to the cap and the cap from becoming too hot.

[0099] (9) In the second embodiment, the carriage carries the liquid ejection unit, and the moving unit moves the carriage back and forth, at least over the medium, together with the first electrode unit, and further includes a waste liquid receiving unit that is arranged outside the medium in the scanning direction and receives the liquid discharged from the liquid ejection unit during a maintenance operation of the liquid ejection unit, and the first electrode unit and the liquid ejection unit are arranged side by side in the scanning direction, and the waste liquid receiving unit is arranged so that at least a portion of the waste liquid receiving unit can be positioned between the first electrode and the second electrode when viewed along an opposing direction in which the medium, the first electrode, and the second electrode are opposed to each other, and the heating control unit, in the heating control, may weaken the electric field strength formed by the first electrode unit compared to the second electric field strength when the waste liquid receiving unit is positioned between the first electrode and the second electrode when viewed along the opposing direction. According to this configuration, when the drainage receiving portion is arranged so that at least a portion of it can be positioned between the first electrode and the second electrode when viewed along the opposing direction, the liquid adhering to the drainage receiving portion can be prevented from being heated by the first electrode unit, thereby preventing the liquid adhering to the drainage receiving portion and the drainage receiving portion from becoming too hot.

[0100] (10) According to a third aspect of the present disclosure, there is provided a liquid ejection device that applies to the medium a liquid heated by an electrode unit, the electrode unit having a first electrode and a second electrode to which an AC voltage is applied, the electrode unit being mounted on a carriage configured to be capable of reciprocating movement along a scanning direction, the electrode unit having a first electrode and a second electrode facing a medium and to which an AC voltage is applied, the electrode unit being mounted on a carriage configured to be capable of reciprocating movement along a scanning direction, the heating control being performed in at least one of an outward path in which the electrode unit moves in one direction of the scanning direction and a return path in which the electrode unit moves in a direction opposite to the one direction, the heating control heating the medium while moving the electrode unit together with the carriage along the scanning direction, the first electric field strength formed by the electrode unit when the electrode unit is located at a first point overlapping with 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 point overlapping with a central portion of the medium in the scanning direction, and the moving speed of the electrode unit at the first point is slower than the moving speed of the electrode unit at the second point. This liquid ejection device includes a transport unit that transports the medium in a direction intersecting the scanning direction, a liquid ejection unit that ejects and applies the liquid to the medium, and a control unit that controls the transport unit and the liquid ejection unit. [Explanation of symbols]

[0101] 20...electrode unit, 30...first electrode unit, 31...first electrode, 32...second electrode, 33...connecting member, 34...first coil, 35...electric wire, 40...second electrode unit, 41...third electrode, 42...fourth electrode, 44...second coil, 80...voltage application section, 100, 100b...dielectric heating device, 110...substrate, 120, 120b...carriage, 130...moving section, 131...endless belt, 132...pulley, 133 ...Drive unit, 140...Air flow generating unit, 180...Heating control unit, 200, 200b...Liquid ejection system, 205, 205b...Liquid ejection device, 210...Liquid ejection unit, 211...Nozzle opening, 212...Nozzle surface, 213...Ejection surface, 220...Cap, 221...Bottom, 222...Edge, 250, 250b...Ejection control unit, 320, 320b...Transport unit, 321...First transport unit, 322...Second transport unit, 323...Roller

Claims

1. a first electrode unit having a first electrode and a second electrode facing the medium and configured to heat the medium by a dielectric heating method; a voltage application unit that applies an AC voltage to the first electrode and the second electrode; a carriage on which the first electrode unit is mounted; a moving unit that moves the carriage back and forth along a scanning direction, thereby moving the first electrode unit back and forth along the scanning direction at least above the medium; a heating control unit that controls the voltage application unit and the movement unit, the heating control unit performs heating control to heat the medium while moving the first electrode unit along the scanning direction, in at least one of an outward 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 a direction opposite to the one direction, The heating control unit, in the heating control, When the first electrode unit is located at a first point that overlaps with one end of the medium in the scanning direction, the electric field intensity formed by the first electrode unit is defined as a first electric field intensity; When the first electrode unit is located at a second point that overlaps with a center portion of the medium in the scanning direction, the electric field intensity formed by the first electrode unit is set to a second electric field intensity that is stronger than the first electric field intensity; A dielectric heating device that slows the moving speed of the first electrode unit at the first point compared to the moving speed of the first electrode unit at the second point.

2. 2. The dielectric heating device according to claim 1, the second electrode is disposed so as to surround the first electrode when viewed along an opposing direction in which the medium faces the first electrode and the second electrode, The first electrode unit has a coil electrically connected in series to the first electrode or the second electrode.

3. 2. The dielectric heating device according to claim 1, a second electrode unit having a third electrode and a fourth electrode facing the medium and configured to heat the medium by a dielectric heating method; the voltage application unit applies an AC voltage to the third electrode and the fourth electrode; the carriage carries the second electrode unit; the moving unit reciprocates the carriage, thereby reciprocating the second electrode unit together with the first electrode unit at least above the medium; The first electrode unit and the second electrode unit are arranged side by side in the scanning direction. A dielectric heating device.

4. The dielectric heating device according to claim 3, the first point 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 located at the first point; the heating control unit, in the heating control, when the first electrode unit is located at the first position, sets an electric field intensity formed by the second electrode unit to a third electric field intensity; The dielectric heating device, wherein the first electric field strength is stronger than the third electric field strength.

5. 2. The dielectric heating device according to claim 1, a transport unit that transports the medium in a transport direction that intersects with the scanning direction; The heating control unit Controlling the conveying unit; alternately performing a transport operation in which the transport unit transports the medium a predetermined transport distance and a rest operation in which the medium is stopped without being transported; Executing the heating control while performing the stationary operation; A dielectric heating device, wherein the length in the transport direction of the area on the medium heated by the first electrode unit while one stationary operation is performed is an integer multiple of the transport distance.

6. 6. The induction heating device according to claim 5, The heating control unit moves the first electrode unit back and forth along the scanning direction while performing one of the stationary operations, and performs the heating control on the outward path and the return path.

7. The dielectric heating device according to any one of claims 1 to 6, a liquid ejection unit having an ejection surface in which nozzle openings are formed, and ejecting and applying liquid from the nozzle openings onto the medium; a discharge control unit that controls the liquid discharge unit.

8. The liquid ejection system according to claim 7, the carriage carries the liquid ejection unit; the moving unit reciprocates the carriage, thereby causing the liquid ejection unit to reciprocate together with the first electrode unit at least above the medium; a cap that is disposed outside the medium in the scanning direction and that is configured to cover at least a portion of the ejection surface, thereby forming a closed space between the ejection surface and the cap, and in which the nozzle openings are open; the first electrode unit and the liquid ejection unit are arranged side by side in the scanning direction, the cap is arranged such that at least a portion of the cap can be positioned between the first electrode and the second electrode when viewed along an opposing direction in which the medium, the first electrode, and the second electrode face each other; A liquid ejection system in which, during the heating control, the heating control unit weakens the electric field strength formed by the first electrode unit compared to the second electric field strength when at least a portion of the cap is positioned between the first electrode and the second electrode when viewed along the opposing direction.

9. The liquid ejection system according to claim 7, the carriage carries the liquid ejection unit; the moving unit reciprocates the carriage, thereby causing the liquid ejection unit to reciprocate together with the first electrode unit at least above the medium; a drainage receiving section that is disposed outside the medium in the scanning direction and receives the liquid that is discharged from the liquid discharger during a maintenance operation of the liquid discharger, the first electrode unit and the liquid ejection unit are arranged side by side in the scanning direction, the waste liquid receiving portion is arranged so that at least a portion of the waste liquid receiving portion can be positioned between the first electrode and the second electrode when viewed along an opposing direction in which the medium, the first electrode, and the second electrode are opposed to each other; A liquid ejection system in which, during the heating control, the heating control unit weakens the electric field strength formed by the first electrode unit compared to the second electric field strength when the waste liquid receiving portion is located between the first electrode and the second electrode when viewed along the opposing direction.

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