Dielectric heating device and liquid dispensing system

Abstract

To uniformly heat a medium in a dielectric heating device.SOLUTION: A dielectric heating device 100 comprises: a conveying section 320 that conveys a medium; electrode units 20 that each face the medium in a first direction, have a first electrode 30 and a second electrode 40 applied with an AC voltage, and heat the medium by a dielectric heating method; and a control section that controls the conveying section. The second electrode is arranged to surround the first electrode when seen along the first direction. The first electrode has a first electric conductor 31, and a second electric conductor 32 protruding toward the medium from the first electric conductor. The second electric conductor is covered by the first electric conductor when they are projected on a plane perpendicular to the first direction.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Regarding dielectric heating devices, Patent Document 1 discloses a device including a planar first electrode having a circular hole and a cylindrical second electrode having an end portion located within the region of the hole when viewed in the direction perpendicular to the first electrode. Patent Document 1 describes that by generating an electric field radially from the second electrode to the first electrode, an object to be heated can be heated uniformly.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the device of Patent Document 1, a portion where the electric field strength is very weak locally occurs directly below the second electrode, which may cause uneven heating. Therefore, there is room for further improvement in heating an object to be heated uniformly.

Means for Solving the Problems

[0005] A dielectric heating device is provided according to a first embodiment of the present disclosure. The dielectric heating device comprises a transport unit for transporting a medium, an electrode unit having a first electrode and a second electrode facing the medium in a first direction and to which an AC voltage is applied, and heating the medium by a dielectric heating method, and a control unit for controlling the transport unit. The second electrode is arranged to surround the first electrode when viewed along the first direction, and the first electrode has a first conductor and a second conductor protruding from the first conductor toward the medium, and when projected onto a plane perpendicular to the first direction, the second conductor is covered by the first conductor.

[0006] A second embodiment of the present disclosure provides a liquid dispensing system comprising a dielectric heating device as described above and a liquid dispensing unit for applying a liquid to a medium. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing the general configuration of a liquid dispensing system as a first embodiment. [Figure 2] A perspective view showing the schematic configuration of the dielectric heating device in the first embodiment. [Figure 3] A perspective view showing the schematic configuration of the electrode unit in the first embodiment. [Figure 4] Figure 3 shows the IV-IV cross-section of the first conductor. [Figure 5] Figure 3 shows the VV cross-section of the first conductor. [Figure 6] A perspective view showing a portion of the first electrode in the first embodiment. [Figure 7] A first side view of the first electrode. [Figure 8] A second side view of the first electrode. [Figure 9] A first explanatory diagram showing the distribution of heating energy in the first embodiment. [Figure 10] An explanatory diagram showing the distribution of heating energy in other forms. [Figure 11] Perspective view of an electrode unit in another configuration. [Figure 12] A perspective view showing a portion of the first electrode of the electrode unit in the second embodiment. [Figure 13] A first explanatory diagram showing the distribution of heating energy in the second embodiment. [Figure 14] A second explanatory diagram showing the distribution of heating energy in the first embodiment. [Figure 15] A second explanatory diagram showing the distribution of heating energy in the second embodiment. [Figure 16] A perspective view showing the schematic configuration of the electrode unit in the third embodiment. [Figure 17] Top view of the electrode unit in the third embodiment. [Figure 18] A schematic diagram showing a first example of an electrode unit in another embodiment. [Figure 19] A schematic diagram showing a second example of an electrode unit in another embodiment. [Figure 20] A schematic diagram showing a third example of an electrode unit in another embodiment. [Modes for carrying out the invention]

[0008] A. First Embodiment: Figure 1 is a schematic diagram showing the general configuration of the liquid discharge system 200 as a first embodiment. Figure 1 shows arrows indicating the mutually orthogonal X, Y, and Z directions. The X and Y directions are parallel to the horizontal plane, and the Z direction is along the vertically upward direction. In other figures, arrows indicating the X, Y, and Z directions are shown as appropriate, so that the directions shown correspond to those in Figure 1. In the following description, when specifying the direction, the direction indicated by the arrow in each figure will be denoted as "+" and the opposite direction as "-", and positive and negative signs will be used in the direction notation. Hereafter, the +Z direction will also be referred to as "up" and the -Z direction as "down". In this specification, orthogonal includes the range of 90° ± 10°. The plane along the X and Y directions will also be referred to as the "XY plane".

[0009] The liquid ejection system 200 includes a dielectric heating device 100 having an electrode unit 20, a liquid ejection device 205, and a conveyance unit 320. The liquid ejection system 200 in the present embodiment ejects and applies a liquid onto a medium Md while the conveyance unit 320 conveys the medium Md, and heats and dries the liquid applied to the medium Md by the electrode unit 20 of the dielectric heating device 100. 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, or fibers obtained by blending these. In the present embodiment, a sheet-like cotton cloth is used as the medium Md. As the liquid applied to the medium Md, for example, various inks are used. In the present embodiment, an aqueous ink mainly composed of water is used as the liquid. In this specification, the main component of the liquid refers to a substance in the liquid whose mass fraction is 50% or more. In other embodiments, as the liquid, in addition to ink, for example, various colorants, electrode materials, samples such as biological organic and inorganic substances, lubricating oils, resin liquids, etching liquids, and any other liquid may be used.

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

[0012] The first conveyance unit 321 is disposed at the +Y direction position of the second conveyance unit 322. In the present embodiment, the first conveyance unit 321 and the second conveyance unit 322 intermittently convey the sheet-like medium Md in the -Y direction. More specifically, the first conveyance unit 321 and the second conveyance unit 322 alternately repeat a moving operation of operating the roller 323 to move the medium Md in the -Y direction and a stationary operation of keeping the medium Md stationary without operating the roller 323.

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

[0014] The liquid ejection unit 210 is configured, for example, as a piezo-type or thermal-type liquid ejection head and has one or more head chips (not shown). Each head chip has a flow path through which the liquid flows and a nozzle for ejecting the liquid. The colors of the ink ejected from each head chip may be the same or different from each other. Further, the liquid ejection unit 210 may be configured to be reciprocally movable in a direction orthogonal to the Z direction and intersecting the Y direction with respect to the medium Md by, for example, a carriage (not shown), or may be configured as a so-called line head whose position is fixed without reciprocally moving with respect to the medium Md.

[0015] In this embodiment, the ink used as a liquid is a pigment ink containing a resin. The resin contained in the ink has the effect of firmly fixing the pigment onto the medium Md through itself. Such a resin is, for example, a resin that is poorly soluble or insoluble in a solvent such as water, and is used in a state in which it is dispersed in the solvent as fine particles, i.e., in an emulsion state or a suspension state. Examples of such resins 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 resins are also called resins.

[0016] The first control unit 250 is comprised of a computer comprising one or more processors, a storage device, and an input / output interface for inputting and outputting signals to and from the outside. In this embodiment, the first control unit 250 controls the liquid discharge unit 210 and the first transport unit 321 to intermittently transport the media Md in the -Y direction while discharging and adhering liquid to the media Md. More specifically, the first control unit 250 performs printing on the media Md by repeatedly discharging liquid onto the media Md during the stationary operation of the first transport unit 321 and moving the media Md in the -Y direction by the movement operation of the first transport unit 321. In other embodiments, the first control unit 250 may be comprised of, for example, a combination of multiple circuits. The first control unit 250 is also referred to as the discharge control unit.

[0017] Figure 2 is a perspective view showing the schematic configuration of the dielectric heating device 100 in the first embodiment. As shown in Figures 1 and 2, the dielectric heating device 100 includes an electrode unit 20 that heats the media Md by a dielectric heating method, a voltage application unit 80 that applies an AC voltage to the electrode unit 20, a second control unit 180, and the second transport unit 322 described above. In this embodiment, the dielectric heating device 100 dries the media Md by transporting it with the second transport unit 322 and heating the media Md with an AC electric field generated from the electrode unit 20. When we say "heat the media Md with an AC electric field," it includes not only heating the media Md itself with an AC electric field, but also heating any adhering substances such as liquids or solids on the media Md with an AC electric field.

[0018] The voltage application unit 80 is electrically connected to the first electrode 30 and the second electrode 40 of the electrode unit 20, which will be described later, and applies an AC voltage with a predetermined drive frequency f0 to the first electrode 30 and the second electrode 40. In this embodiment, the voltage application unit 80 is configured as a high-frequency power supply including a high-frequency voltage generation circuit, and includes a crystal oscillator, a PLL (Phase Locked Loop) circuit, and a power amplifier, respectively (not shown). In other embodiments, the voltage application unit 80 may be configured as an inverter equipped with a switching circuit having switching elements such as a transistor. One of the potentials applied to the first electrode 30 or the second electrode 40 may be a reference potential. The reference potential is a constant potential that serves as a reference for the high-frequency voltage, for example, the ground potential.

[0019] In this embodiment, a high-frequency voltage is applied to each electrode of the electrode unit 20. In this specification, "high frequency" refers to a frequency of 1 MHz or higher. More specifically, in this embodiment, 13.56 MHz, one of the Industrial Scientific and Medical Band (ISM) bands, is used as the driving frequency f0. Since the dielectric loss tangent of water is maximum around 20 GHz, applying high-frequency voltages of 2.45 GHz or 5.8 GHz from the ISM band to each electrode of the electrode unit 20 allows for more efficient heating of the liquid attached to the media Md. On the other hand, from the perspective of heating the ink, good heating efficiency can be obtained even when the driving frequency f0 is relatively low, such as 13.56 MHz or 40.68 MHz. This is because when the driving frequency f0 is 13.56 MHz or 40.68 MHz, the dielectric loss tangent of water in the ink is low, while Joule heat is more easily generated due to the electrical resistance of the pigment components in the ink.

[0020] The second control unit 180, like the first control unit 250 described above, is configured by a computer. The second control unit 180 controls the second transport unit 322 described above to transport the media Md. In this embodiment, regardless of whether the second transport unit 322 is performing a moving operation or a stationary operation, an AC voltage is applied to the electrode unit 20, and the electrode unit 20 heats the media Md. Hereafter, the second control unit 180 will also be simply referred to as the control unit.

[0021] As shown in Figure 2, in this embodiment, the dielectric heating device 100 has seven electrode units 20. More specifically, in this embodiment, the dielectric heating device 100 has a first electrode unit row 21 and a second electrode unit row 22. The first electrode unit row 21 consists of four electrode units 20 arranged at equal intervals in the X direction. The second electrode unit row 22 consists of three electrode units 20 arranged at equal intervals in the X direction. The second electrode unit row 22 is located in the -Y direction relative to the first electrode unit row 21. The first electrode unit row 21 and the second electrode unit row 22 are separated by a distance D in the Y direction. In this embodiment, the distance D is approximately the same as the distance the media Md moves in one movement operation by the first transport unit 321 described above, and is approximately the same as the dimension of the electrode unit 20 in the Y direction. In other embodiments, for example, the number of electrode units 20 may be six or fewer, or eight or more. Furthermore, the arrangement of each electrode unit 20 may be arbitrary.

[0022] Figure 3 is a perspective view showing the schematic configuration of the electrode unit 20 in this embodiment. As shown in Figures 1 to 3, the electrode unit 20 has a first electrode 30 and a second electrode 40. The electrode unit 20 in this embodiment also has a coil 50.

[0023] The first electrode 30 and the second electrode 40 are conductors and are formed from, for example, metals, alloys, conductive oxides, etc. The first electrode 30 and the second electrode 40 may be formed from the same material or from different materials. The first electrode 30 and the second electrode 40 may be placed on a substrate or the like made of a material with low dielectric loss tangent or conductivity, for example, to maintain their orientation and strength, or they may be supported by other members.

[0024] The first electrode 30 and the second electrode 40 face the media Md in a first direction. The first direction includes both one direction along the same axis and the opposite direction, and in this embodiment, it is the Z direction.

[0025] The first electrode 30 has a first conductor 31 and a second conductor 32. The second conductor 32 protrudes from the first conductor 31 toward the medium Md and is covered by the first conductor 31 when projected onto the XY plane. The first conductor 31 and the second conductor 32 may be separate or integrated.

[0026] The first conductor 31 in this embodiment has an elongated shape with a longitudinal direction along the second direction and a transverse direction along the third direction. The second direction is perpendicular to the first direction. The second direction includes both one direction along the same axis and the opposite direction, and in this embodiment, it is the X direction. The third direction is perpendicular to both the first and second directions. The third direction includes both one direction along the same axis and the opposite direction, and in this embodiment, it is the Y direction.

[0027] In this embodiment, the first conductor 31 has a curved plate shape that, as a whole, has a curved surface shape that is convex in the -Z direction. The first electrode 30 has an elongated shape with the X direction as the longitudinal direction and the Y direction as the short direction when viewed along the Z direction. In this embodiment, the first conductor 31 can also be said to have a boat-shaped form that extends along the X direction.

[0028] Figure 4 shows the IV-IV cross-section of the first conductor 31 in Figure 3. Figure 5 shows the VV cross-section of the first conductor 31 in Figure 3. As shown in Figures 3 and 5, the first conductor 31 has a convex arc shape in the -Z direction when viewed along the X direction. Similarly, as shown in Figures 3 and 4, the first conductor 31 has a convex arc shape in the -Z direction when viewed along the Y direction.

[0029] As shown in Figures 3 to 5, the first conductor 31 in this embodiment has a rounded shape overall, with few sharp corners. This suppresses the concentration of the electric field at specific parts of the first conductor 31, such as its ends. Furthermore, in this embodiment, because the first conductor 31 has a boat-shaped form, the distance in the Z direction between the ends of the first conductor 31 in the longitudinal and transverse directions and the media Md is longer than the distance in the Z direction between the central part of the first conductor 31 in the longitudinal and transverse directions and the media Md. This further suppresses the concentration of the electric field at the ends of the first electrode 30. In addition, the radius of curvature R of the end of the first conductor 31 in the X direction shown in Figure 5 is larger than the radius of curvature r of the end of the first conductor 31 in the Y direction shown in Figure 4. This further suppresses the concentration of the electric field at the end of the first conductor 31 in the longitudinal direction.

[0030] Figure 6 is a perspective view showing a part of the first electrode 30. Figure 7 is a first side view of the first electrode 30. Figure 8 is a second side view of the first electrode 30. Figure 7 shows the first electrode 30 as viewed along the X direction. Figure 8 shows the first electrode 30 as viewed along the Y direction.

[0031] As shown in Figure 6, in this embodiment, the second conductor 32 has an elongated shape with a longitudinal direction along the X direction and a transverse direction along the Y direction when viewed along the Z direction. Also, as shown in Figure 7, in this embodiment, the second conductor 32 has a shape that is symmetrical in the Y direction with respect to a line L1 passing through the center of the first conductor 31 in the Y direction when viewed along the X direction. Therefore, when viewed along the X direction, the center position of the first conductor 31 in the Y direction and the center position of the second conductor 32 in the Y direction coincide. Also, as shown in Figure 8, the second conductor 32 has a shape that is symmetrical in the X direction with respect to a line L2 passing through the center of the first conductor 31 in the X direction when viewed along the Y direction. Therefore, when viewed along the Y direction, the center position of the first conductor 31 in the X direction and the center position of the second conductor 32 in the X direction coincide.

[0032] As shown in Figures 6 to 8, the second conductor 32 has, in the Z direction, a first end 33 connected to the first conductor 31, a second end 34 on the opposite side of the first conductor 31, and an intermediate portion 35 positioned between the first end 33 and the second end 34. In this embodiment, the second end 34, the intermediate portion 35, and the first end 33 are arranged in this order from bottom to top. As shown in Figure 7, the width Wm of the intermediate portion 35 in the Y direction is wider than the width W1 of the first end 33 in the Y direction and the width W2 of the second end 34 in the Y direction. Also, when projected onto the XY plane perpendicular to the Z direction, the first end 33 and the second end 34 are covered by the intermediate portion 35. In other words, when projected onto the XY plane, the entirety of the first end 33 and the entirety of the second end 34 overlap with the intermediate portion 35. In this embodiment, widths W1 and W2 are the same.

[0033] As shown in Figure 7, in this embodiment, the second conductor 32 has a cross shape when viewed along the X direction. More specifically, the second conductor 32 has a flat plate-shaped first portion P1 extending along the X and Z directions, a rectangular plate-shaped second portion P2 extending along the X and Y directions so as to project in the +Y direction from the central portion Pc in the Z direction of the first portion P1, and a rectangular plate-shaped third portion P3 extending along the X and Y directions so as to project in the -Y direction from the central portion Pc. The first portion P1 is positioned to extend downward from the central portion in the Y direction of the first conductor 31 when viewed along the X direction. The first end portion 33 described above is formed by the upper end portion of the first portion P1. The second end portion 34 is formed by the lower end portion of the first portion P1. The intermediate portion 35 is formed by the central portion Pc, the second portion P2, and the third portion P3.

[0034] As shown in Figure 8, in this embodiment, one end 37 of the second conductor 32, including one end 36 in the X direction, has a shape in which the distance in the Z direction between it and the media Md gradually increases from the opposite side of the end 36 toward the end 36 in the X direction. Similarly, in this embodiment, the other end 39 of the second conductor 32, including the other end 38 in the X direction, has a shape in which the distance in the Z direction between it and the media Md gradually increases from the opposite side of the other end 38 toward the other end 38 in the X direction. More specifically, the portion of the first portion P1 located below the second portion P2 and the third portion P3 is formed in a substantially trapezoidal plate shape that is convex downwards.

[0035] As shown in Figure 3, the second electrode 40 is positioned to surround the first electrode 30 when viewed along the Z direction. In this embodiment, the second electrode 40 has an oblong ring shape that is flattened in the X and Y directions. Similar to the first electrode 30, the second electrode 40 has an elongated shape with the X direction as the longitudinal direction and the Y direction as the short direction when viewed along the Z direction. The first electrode 30 and the second electrode 40 are positioned such that the shortest distance between the first electrode 30 and the second electrode 40 is one-tenth or less of the wavelength of the electromagnetic field output from the electrode unit 20.

[0036] In other embodiments, the second electrode 40 may have, for example, a circular, rectangular, or polygonal annular shape. Also, when it is said that "the second electrode 40 is arranged to surround the first electrode 30 when viewed along the Z direction," it is sufficient that the second electrode 40 as a whole surrounds more than half of the periphery of the first electrode 30 when viewed along the Z direction, and it is not necessary for the second electrode 40 to surround the entire periphery of the first electrode 30 without any gaps. Therefore, in other embodiments, the second electrode 40 may have, for example, a so-called C-shape or U-shape when viewed along the Z direction. Alternatively, the second electrode 40 may have a shape that, for example, surrounds the first electrode 30 as a whole while being intermittently interrupted when viewed along the Z direction. In this case, the second electrode 40 is configured such that the same potential is applied to each part of the second electrode 40 when an AC voltage is applied to the first electrode 30 and the second electrode 40.

[0037] As shown in Figures 1 and 2, the first electrode 30 and the second electrode 40 are both positioned on a substrate 110 that is parallel to the X and Y directions. More specifically, the first electrode 30 is positioned so that the lower end surface of the first end 33 of the first conductor 31 is in contact with the upper surface of the substrate 110. The second electrode 40 is positioned so that the lower surface of the second electrode 40 is in contact with the upper surface of the substrate 110. Therefore, in this embodiment, the shortest distance in the Z direction between the first electrode 30 and the media Md is equal to the shortest distance in the Z direction between the second electrode 40 and the media Md. It can also be said that the lower end surface of the first end 33 and the lower surface of the second electrode 40 are positioned on the same plane.

[0038] The substrate 110 prevents liquids such as ink applied to the media Md from adhering to the first electrode 30 and the second electrode 40, and also prevents lint from the media Md from adhering to the first electrode 30 and the second electrode 40 if the media Md is cloth. In this embodiment, a single substrate 110 made of glass is provided in common to all electrode units 20. In other embodiments, the substrate 110 may be made of alumina, for example. Alternatively, the substrate 110 may be provided individually, for example, corresponding to each electrode unit 20.

[0039] Let's return to the explanation of Figure 3. In this embodiment, the first electrode 30 is electrically connected to the voltage application unit 80 via the electric wire 55, the coil 50, and the internal conductor IC1 of the coaxial cable. The second electrode 40 is electrically connected to the voltage application unit 80 via a connecting member 56 located on the upper part of the second electrode 40, or via the external conductor of the coaxial cable (not shown).

[0040] In this embodiment, one end of the coil 50 is electrically connected in series with the first electrode 30 via an electric wire 55, and the other end of the coil 50 is electrically connected in series with the voltage application unit 80 shown in Figures 1 and 2. In this embodiment, the coil 50 is composed of a solenoid coil and is arranged so that its length is aligned with the Z direction. The shape, length, cross-sectional area, number of turns, material, etc., of the coil 50 are selected, for example, according to the driving frequency f0 and to achieve impedance matching between the electrode unit 20 and the voltage application unit 80. In other embodiments, one end of the coil 50 may be connected in series with the second electrode 40 instead of the first electrode 30.

[0041] When an AC voltage with a driving frequency f0 is applied to the first electrode 30 and the second electrode 40, an electromagnetic field having a wavelength corresponding to the driving frequency f0 is generated from the first electrode 30 and the second electrode 40. The strength of this electromagnetic field is very strong in the vicinity of the first electrode 30 and the second electrode 40, and very weak at a distance. In this specification, the electromagnetic field generated in the vicinity of the first electrode 30 and the second electrode 40 by the application of an AC voltage is also called the "nearby electromagnetic field." "Nearby" of the first electrode 30 and the second electrode 40 refers to the range where the distance from the first electrode 30 and the second electrode 40 is 1 / 2π or less of the wavelength of the generated electromagnetic field. The range further than "nearby" is also called "far." In this specification, the electromagnetic field generated far from the first electrode 30 and the second electrode 40 by the application of an AC voltage is also called the "far electromagnetic field." The far electromagnetic field corresponds to the electromagnetic field used for communication by general communication antennas, etc.

[0042] As described above, by having the shortest distance between the first electrode 30 and the second electrode 40 be less than one-tenth of the wavelength of the electromagnetic field, the density of the electromagnetic field generated from the first electrode 30 and the second electrode 40 can be attenuated in the vicinity of the first electrode 30 and the second electrode 40. Therefore, by appropriately maintaining the distance between the media Md and the first electrode 30 and the second electrode 40, the liquid adhering to the media Md can be efficiently heated by the electric field generated in the vicinity of the first electrode 30 and the second electrode 40, while suppressing the radiation of far-field electromagnetic fields from the first electrode 30 and the second electrode 40. In particular, in this embodiment, since the second electrode 40 is arranged to surround the first electrode 30 when viewed along the Z direction, the radiation of far-field electromagnetic fields from the first electrode 30 and the second electrode 40 can be further suppressed.

[0043] When an AC voltage is applied to the electrode unit 20, a high voltage is generated at one end of the coil 50. This increases the strength of the electric field generated from the first electrode 30 and the second electrode 40. Preferably, the coil 50 is positioned such that the distance between one end of the coil 50 and the first electrode 30 is as small as possible. If the distance between one end of the coil 50 and the first electrode 30 is large, the high voltage generated at one end of the coil 50 may generate an electric field between the coil 50 and the first electrode 30, or between the wire 55 and the second electrode 40, which does not contribute to heating the media Md, potentially reducing the effect of increasing the strength of the electric field generated from the first electrode 30 and the second electrode 40. In contrast, by reducing the distance between one end of the coil 50 and the first electrode 30, the generation of such an electric field that does not contribute to heating the media Md can be suppressed, thereby effectively increasing the strength of the electric field generated from the first electrode 30 and the second electrode 40. In other embodiments, the electrode unit 20 does not necessarily have a coil 50. For example, the first electrode 30 may be formed in a meander shape to allow the first electrode 30 to perform the same function as the coil 50.

[0044] Figure 9 is a first explanatory diagram showing the distribution of heating energy in the first embodiment. Figure 9 shows the results of an electromagnetic field simulation of heating the media Md by the electrode unit 20. More specifically, Figure 9 shows the simulation results of the power consumption density in region Rs when a sheet-like media Md, uniformly coated with ink on its upper surface, is placed facing the first electrode 30 and second electrode 40 of one electrode unit 20, and a high-frequency voltage of 13.56 MHz is applied to the first electrode 30 and second electrode 40. Region Rs is a rectangular region on the upper surface of the media Md that overlaps with the first electrode 30 and second electrode 40 when viewed along the Z direction. In this simulation result, the distribution of power consumption density in region Rs is shown in 15 steps by different colors. For example, the area with the lowest power consumption density is shown in dark blue, and the area with the highest power consumption density is shown in red. In Figure 9, a higher power consumption density in a certain area means that the heating energy in that area is greater.

[0045] Figure 10 is an explanatory diagram showing the distribution of heating energy in other configurations. Figure 11 is a perspective view of the electrode unit 20p in other configurations. Figure 10 shows the results of an electromagnetic field simulation of the heating of the medium Md by the electrode unit 20p. The simulation conditions in Figure 10 are the same as those in the simulation in Figure 9, except that the electrode unit 20p was used. The display method of the simulation results in Figure 10 is also the same as that of the simulation in Figure 9. As shown in Figure 11, the configuration of the electrode unit 20p corresponds to a configuration in which the first electrode 30 of the electrode unit 20 is replaced by electrode 30p. Electrode 30p is composed only of a portion having the same shape as the first conductor 31, and the lower surface of its central part is located on the same plane as the lower surface of the second electrode 40 of the electrode unit 20p. Hereinafter, electrodes surrounded by the second electrode 40 when viewed in the Z direction, such as the first electrode 30 and electrode 30p, will also be called inner electrodes. The central part of region Rs shown in Figures 9 and 10 overlaps with the central parts of the inner electrode in the X and Y directions.

[0046] In the simulation results shown in Figures 9 and 10, heating regions Ht1 and Htp were observed, respectively, within region Rs, extending in an approximately oval shape surrounding the blank region described later. The positions of the outer edges of heating regions Ht1 and Htp roughly coincide with the positions on the upper surface of the media Md that overlap with the outer edge of the second electrode 40. In the simulation results shown in Figures 9 and 10, the power consumption density was at the fourth stage in most of heating regions Ht1 and Htp. For example, point Pt1 shown in Figure 9 and point Pt2 shown in Figure 10 are locations where the power consumption density was at the fourth stage.

[0047] In Figures 9 and 10, blank regions BR1 and BRp were generated in the center of region Rs, respectively. A blank region is a region where the intensity of the near-field electric field is very weak, occurring locally within the area of ​​the upper surface of the media Md that overlaps with the central electrode when viewed along the Z direction. Therefore, the media Md is hardly heated in the blank region. In the simulation results of Figures 9 and 10, the power consumption density in blank regions BR1 and BRp is at the first stage. The power consumption density at the first stage is less than one-third of the power consumption density at the fourth stage described above. Blank regions BR1 and BRp may also include areas where the power consumption density is almost zero.

[0048] The area of ​​blank region BR1 shown in Figure 9 was smaller than the area of ​​blank region BRp shown in Figure 10. This is thought to be because, in this embodiment, an electric field contributing to the heating of the media Md is formed between the second conductor 32 and the second electrode 40, which reduces the area where the strength of the nearby electric field is very weak.

[0049] Although not shown in the diagram, if the inner electrode is formed only from a portion having the same shape as the second conductor 32, the variation in heating energy near the blank region will increase compared to the case where the inner electrode is formed from the first conductor 31 and the second conductor 32. Furthermore, in this embodiment, since the width of the intermediate portion 35 of the second conductor 32 is wider than the width of the first end portion 33 and the second end portion 34, the variation in heating energy near the blank region BR1 can be further suppressed. In particular, in this embodiment, when projected onto the XY plane, the first end portion 33 and the second end portion 34 are covered by the intermediate portion 35, so the variation in electric field strength near the blank region BR1 can be further suppressed.

[0050] Unlike this embodiment, when heating media Md using the electrode unit 20p shown in Figure 11, insufficient heating in the blank region BRp can result in uneven heating of the media Md. In particular, when the media Md is transported intermittently as in this embodiment, insufficient heating is likely to occur in the area of ​​the media Md that becomes the blank region BRp during stationary operation. Also, for example, if the movement speed of the media Md relative to the electrode unit 20p is relatively high, insufficient heating originating from the blank region BRp is likely to occur. Therefore, when heating media Md using the electrode unit 20p, it is necessary to, for example, position the electrode unit 20p so that the insufficient heating can be compensated for, transport the media Md sufficiently slowly relative to the electrode unit 20p, or move the media Md back and forth in small increments relative to the electrode unit 20p so that the area of ​​the media Md that becomes the blank region BRp is not fixed. In contrast, in this embodiment, the area of ​​the blank region can be made smaller, so the degree of freedom in the arrangement of the electrode unit 20 and the manner of transporting the media Md can be increased. More specifically, for example, even when the movement speed of the media Md relative to the electrode unit 20 is relatively fast, the likelihood of uniform heating of the media Md increases. Furthermore, even when compensating for insufficient heating by moving the media Md back and forth in small increments relative to the electrode unit 20 as described above, the range of movement can be made smaller.

[0051] According to the dielectric heating device 100 of the first embodiment described above, the first electrode 30 has a first conductor 31 and a second conductor 32 that protrudes from the first conductor 31 toward the media Md, and when projected onto the XY plane perpendicular to the Z direction, the second conductor 32 is covered by the first conductor 31. With this configuration, the area of ​​the blank region can be made smaller by the second conductor 32. In other words, the second conductor 32 can suppress the occurrence of a region in the media Md that overlaps with the first electrode 30 in which the local near-field electric field strength is very weak. Therefore, the possibility of heating the media Md evenly is increased.

[0052] Furthermore, in this embodiment, the first conductor 31 and the second conductor 32 have an elongated shape with a longitudinal direction along the X direction and a short direction along the Y direction when viewed along the Z direction. Therefore, in the form in which the first conductor 31 has an elongated shape, the area of ​​the blank region can be effectively reduced by the second conductor 32, which also has an elongated shape similar to the first conductor 31.

[0053] Furthermore, in this embodiment, the second conductor 32 has, in the Z direction, a first end 33 connected to the first conductor 31, a second end 34 opposite to the first end 33, and an intermediate portion 35 positioned between the first end 33 and the second end 34, with a width in the Y direction wider than that of the first end 33 and the second end 34. This makes it possible to further suppress variations in electric field strength near the blank region compared to, for example, a configuration without an intermediate portion 35 wider than that of the first end 33 and the second end 34. Therefore, the possibility of uniformly heating the media Md is increased.

[0054] Furthermore, in this embodiment, when projected onto the XY plane, the first end portion 33 and the second end portion 34 are covered by the intermediate portion 35. Therefore, variations in electric field strength near the blank region can be further suppressed.

[0055] Furthermore, in this embodiment, the second conductor 32 has a cross shape when viewed along the X direction. Therefore, with a simple configuration, the area of ​​the blank region can be reduced, and variations in the electric field strength near the blank region can be suppressed.

[0056] Furthermore, in this embodiment, the end portion 37 of the second conductor 32, including the end portion 36 in the X direction, has a shape in which the distance in the Z direction between it and the media Md gradually increases from the opposite side of the end portion 36 toward the end portion 36 in the X direction. Therefore, electric field concentration at the end portion 36 can be suppressed.

[0057] Furthermore, in this embodiment, the radius of curvature R at the end of the first conductor 31 in the longitudinal direction is greater than the radius of curvature r at the end of the first conductor 31 in the short direction. Therefore, electric field concentration at the end of the first conductor 31 in the longitudinal direction can be suppressed.

[0058] Furthermore, in this embodiment, the shortest distance in the Z direction between the first electrode 30 and the media Md is equal to the shortest distance in the Z direction between the second electrode 40 and the media Md. Therefore, the possibility of uniform heating of the media Md is increased. In addition, when heating a sheet-shaped media Md as in this embodiment, it becomes easier to generate an electric field along the planar direction of the media Md between the first electrode 30 and the second electrode 40, so the media Md can be heated more efficiently.

[0059] B. Second Embodiment: Figure 12 is a perspective view showing a portion of the first electrode 30b of the electrode unit 20b in the second embodiment. In this embodiment, unlike the first embodiment, the second conductor 32b of the first electrode 30b does not have a cross shape when viewed along the X direction. The configuration of the electrode unit 20b and the dielectric heating device 100 in the second embodiment is the same as in the first embodiment unless otherwise described.

[0060] The second conductor 32b has a flat plate shape along the X and Z directions. Therefore, when viewed along the X direction, the second conductor 32b has a so-called "I" shape that extends linearly along the Z direction. More specifically, the shape of the second conductor 32b in this embodiment corresponds to a shape in which the width Wm of the intermediate portion 35 of the first conductor 31 is the same as the width W1 of the first end portion 33 and the width W2 of the second end portion 34.

[0061] Figure 13 is the first explanatory diagram showing the distribution of heating energy in the second embodiment. Figure 13 shows the results of a simulation of heating the media Md by the electrode unit 20b using electromagnetic field simulation. The simulation conditions in Figure 13 are the same as those of the simulation in Figure 9 described in the first embodiment, except that the electrode unit 20b was used. Also, the display method of the simulation results in Figure 13 is the same as that of the simulation in Figure 9.

[0062] In the simulation results shown in Figure 13, a heated region Ht2 was observed within region Rs, similar to Figures 9 and 10. In the simulation results of Figure 13, the power consumption density was at the fourth level in most of the heated region Ht2. For example, point Pt3 shown in Figure 9 is a location where the power consumption density was at the fourth level. Also, a blank region BR2 was formed in the central part of region Rs in Figure 13, similar to Figures 9 and 10. The area of ​​blank region BR2 is smaller than the area of ​​blank region BRp shown in Figure 10. Therefore, in the second embodiment, similar to the first embodiment, it is considered that the area with a very weak nearby electric field strength was reduced.

[0063] Figure 14 is a second explanatory diagram showing the distribution of heating energy in the first embodiment. Figure 15 is a second explanatory diagram showing the distribution of heating energy in the second embodiment. Figure 14 is an enlarged view of the area around blank region BR1 within region Rs in Figure 9. Figure 15 is an enlarged view of the area around blank region BR2 within region Rs in Figure 13. Figures 14 and 15 show approximately the same range within the media Md.

[0064] In Figures 14 and 15, hatching is applied to areas where the heating energy is relatively high. More specifically, areas where the power consumption density is between levels 15 and 11 are hatched upwards to the right, and areas where the power consumption density is between levels 6 and 10 are hatched downwards to the right. As shown in Figures 14 and 15, in the second embodiment, compared to the first embodiment, the areas with relatively high heating energy are widely distributed near the blank region BR2. Thus, in the first embodiment, it can be seen that the variation in heating energy near the blank region is smaller compared to the second embodiment.

[0065] In the second embodiment, for example, it is possible to compensate for the insufficient heating in the blank region BR2 by utilizing the fact that areas with relatively high heating energy are more widely distributed near the blank region BR2.

[0066] According to the second embodiment described above, the second conductor 32b has a flat plate shape along the Z and X directions. Therefore, the area of ​​the blank region can be reduced with a simpler configuration.

[0067] C. Third Embodiment: Figure 16 is a perspective view showing the schematic configuration of the electrode unit 20c in the third embodiment. Figure 17 is a top view of the electrode unit 20c. In Figure 17, the connecting member 56 is omitted. Unlike the first embodiment, the electrode unit 20c includes a third electrode 90. The configuration of the electrode unit 20c and the dielectric heating device 100 in the third embodiment is the same as in the first embodiment, except for parts that are not specifically described.

[0068] The third electrode 90 is a conductor and is positioned between the first electrode 30 and the second electrode 40. The third electrode 90 is not electrically connected to the power supply or voltage application unit 80 and is electrically insulated from the first electrode 30 and the second electrode 40. The third electrode 90 is supported by an insulator, for example (not shown). The third electrode 90 may be made of the same material as the first electrode 30 and the second electrode 40, or it may be made of a different material. The third electrode 90 is also called a floating electrode.

[0069] More specifically, in this embodiment, the third electrode 90 is positioned to surround the first electrode 30 when viewed along the Z direction. The third electrode 90 has an oblong annular shape that is flattened in the X and Y directions. Like the first electrode 30 and the second electrode 40, the third electrode 90 has an elongated shape with the X direction as the longitudinal direction and the Y direction as the short direction when viewed along the Z direction. The second electrode 40 is positioned to surround the third electrode 90 and the first electrode 30 surrounded by the third electrode 90 when viewed along the Z direction. In other embodiments, the third electrode 90 does not need to be positioned to surround the first electrode 30 when viewed along the Z direction, as long as it is positioned between the first electrode 30 and the second electrode 40.

[0070] According to the third embodiment described above, a third electrode 90 is provided, which is positioned between the first electrode 30 and the second electrode 40 and electrically insulated from the first electrode 30 and the second electrode 40. With this configuration, the third electrode 90 can reduce the variation in the strength of the electric field generated between the first electrode 30 and the second electrode 40. Therefore, the possibility of uniformly heating the media Md is increased.

[0071] D. Other embodiments: (D-1) Figure 18 schematically shows an example of an electrode unit 20d in another embodiment. In Figure 18, the second conductor 32 of the first electrode 30c of the electrode unit 20d is positioned such that, when viewed along the X direction, the center position of the second conductor 32 in the Y direction is located on the -Y direction side than the center position of the first conductor 31 in the Y direction. The first electrode 30 may be configured in this way. Alternatively, for example, when viewed along the Y direction, the center position of the second conductor 32 in the X direction may be located on the +X direction side or the -X direction side than the center position of the second conductor 32 in the X direction.

[0072] (D-2) Figure 19 schematically shows an example of an electrode unit 20e in another embodiment. The first electrode 30d of the electrode unit 20e in Figure 19 has two second conductors 32. More specifically, when viewed along the X direction, one second conductor 32 is positioned on the -Y side of the center position of the first conductor 31 in the Y direction, and the other second conductor 32 is positioned on the +Y side of the center position of the first conductor 31 in the Y direction. Thus, the first electrode 30d may have two second conductors 32. Alternatively, the first electrode 30d may have three or more second conductors 32.

[0073] (D-3) Figure 20 schematically shows an example of an electrode unit 20f in another embodiment. In Figure 20, the second conductor 32c of the first electrode 30e of the electrode unit 20f has a so-called V-shape when viewed along the X direction. Thus, the second conductor 32c may have a shape different from a cross shape or an I-shape when viewed along the X direction.

[0074] (D-4) In the above embodiment, the first conductor 31 has a boat shape, but it does not have to have a boat shape, and may have, for example, a flat plate shape, a rod shape, a plate shape with a V-shaped cross-section, etc. Also, in the above embodiment, the first conductor 31 has an oval shape when viewed along the Z direction, but it does not have to have an oval shape, and may have, for example, a circular shape, a rectangular shape, or other polygonal shape, etc.

[0075] (D-5) In the above embodiment, the first conductor 31 and the second conductor 32 have an elongated shape with the X direction as their longitudinal direction when viewed along the Z direction. In contrast, for example, the first conductor 31 and the second conductor 32 do not have to have an elongated shape. In this case, for example, when viewed along the Z direction, the first conductor 31 and the second conductor 32 may have a circular or square shape. Also, when viewed along the Z direction, either the first conductor 31 or the second conductor 32 may have an elongated shape while the other does not. Furthermore, for example, the first conductor 31 and the second conductor 32 may each have an elongated shape with different longitudinal directions.

[0076] (D-6) In the above embodiment, if the second conductor 32 is formed such that, when projected onto a plane perpendicular to the Z direction, the first end 33 and the second end 34 are covered by the intermediate portion 35, as in the first embodiment, the second conductor 32 does not need to be formed to have a cross shape when viewed along the X direction. Also, the second conductor 32 does not need to be formed such that, when projected onto a plane perpendicular to the Z direction, the first end 33 and the second end 34 are covered by the intermediate portion 35.

[0077] (D-7) In the above embodiment, one end 37 of the second conductor 32 in the X direction has a shape in which the distance in the Z direction between it and the media Md gradually increases from the opposite side of the end 36 toward the end 36 in the X direction. However, the one end 37 of the second conductor 32 does not have to have such a shape. Similarly, the other end 39 does not have to have a shape in which the distance in the Z direction between it and the media Md gradually increases from the opposite side of the other end 38 toward the other end 38 in the X direction. In this case, the second conductor 32 may be formed to have, for example, a rectangular shape or an upwardly convex trapezoidal shape when viewed along the Y direction.

[0078] (D-8) In the above embodiment, the radius of curvature R of the end of the first conductor 31 in the longitudinal direction is greater than the radius of curvature r of the end of the first conductor 31 in the short direction. In contrast, the radius of curvature R may be smaller than the radius of curvature r, or it may be the same as the radius of curvature r.

[0079] (D-9) In the above embodiment, the shortest distance in the Z direction between the first electrode 30 and the media Md is equal to the shortest distance in the Z direction between the second electrode 40 and the media Md. In contrast, the shortest distance in the Z direction between the first electrode 30 and the media Md does not have to be equal to the shortest distance in the Z direction between the second electrode 40 and the media Md. In this case, for example, the lower end of the first conductor 31 of the first electrode 30 may be located above or below the lower end of the second electrode 40.

[0080] (D-10) In the above embodiment, the media Md is conveyed intermittently. In contrast, the media Md may be conveyed in the -Y direction at a constant speed without stopping along the way by, for example, the first conveying unit 321 or the second conveying unit 322.

[0081] (D-11) In the above embodiment, the media Md is continuously transported from the liquid dispensing device 205 to the dielectric heating device 100. When the media Md is continuously transported from the liquid dispensing device 205 to the dielectric heating device 100 in this manner, the transport unit 320 may have, for example, only a transport unit common to both the dielectric heating device 100 and the liquid dispensing device 205. Alternatively, the media Md does not have to be continuously transported from the liquid dispensing device 205 to the dielectric heating device 100. For example, the media Md coated with liquid by the liquid dispensing device 205 may be wound into a roll, and then the media Md may be moved to the dielectric heating device 100 by a robot or the like. In this case, the dielectric heating device 100 can heat the media Md while transporting it by the second transport unit 322 or the like, for example, while unwinding the media Md that has been wound into a roll.

[0082] (D-12) In the above embodiment, a frequency of 13.56 MHz is used as the drive frequency f0. However, the drive frequency f0 does not have to be 13.56 MHz; for example, other ISM band frequencies such as 40.68 MHz, 2.45 GHz, or 5.8 GHz may be used. Furthermore, the drive frequency f0 does not have to be a high frequency as long as it is a frequency that can heat the media Md. In this case, the drive frequency f0 is preferably, for example, 100 kHz or more and less than 1 MHz.

[0083] (D-13) In the above embodiment, the dielectric heating device 100 is incorporated into the liquid discharge system 200. However, the dielectric heating device 100 does not have to be incorporated into the liquid discharge system 200; for example, the dielectric heating device 100 may be used on its own.

[0084] E. Other forms: This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, this disclosure can also be implemented in the following forms. The technical features in the embodiments described below that correspond to the technical features in each of the forms described below can be replaced or combined as appropriate in order to solve some or all of the problems of this disclosure, or to achieve some or all of the effects of this disclosure. Furthermore, if such technical features are not described as essential in this specification, they can be deleted as appropriate.

[0085] (1) According to a first embodiment of the present disclosure, a dielectric heating device is provided. The dielectric heating device comprises a transport unit for transporting a medium, an electrode unit having a first electrode and a second electrode facing the medium in a first direction and to which an AC voltage is applied, and heating the medium by a dielectric heating method, and a control unit for controlling the transport unit. The second electrode is arranged to surround the first electrode when viewed along the first direction, and the first electrode has a first conductor and a second conductor protruding from the first conductor toward the medium, and when projected onto a plane perpendicular to the first direction, the second conductor is covered by the first conductor. This configuration allows the second conductor to suppress the occurrence of areas within the media that overlap with the first electrode where the alternating electric field strength is extremely weak. Therefore, the likelihood of uniform heating of the media increases.

[0086] (2) In the above embodiment, the first conductor and the second conductor may have an elongated shape, when viewed along the first direction, having a longitudinal direction along a second direction perpendicular to the first direction and a short direction along a third direction perpendicular to both the first and second directions. In such an embodiment, in the embodiment in which the first conductor has an elongated shape, the second conductor, which also has an elongated shape similar to the first conductor, can effectively suppress the occurrence of areas where the strength of the AC electric field is locally very weak.

[0087] (3) In the above embodiment, the second conductor may have, in the first direction, a first end connected to the first conductor, a second end opposite to the first end, and an intermediate portion positioned between the first end and the second end, with a width in the third direction that is wider than the first end and the second end. With such an embodiment, variations in the electric field strength in the media can be further suppressed. Therefore, the possibility of heating the media evenly is increased.

[0088] (4) In the above configuration, when projected onto a plane perpendicular to the first direction, the first end and the second end are covered by the intermediate portion. With this configuration, variations in electric field strength can be further suppressed.

[0089] (5) In the above embodiment, the second conductor may have a cross shape when viewed along the second direction. With such an embodiment, it is possible to suppress the occurrence of areas where the strength of the AC electric field is very weak locally with a simple configuration, and to suppress variations in the electric field strength.

[0090] (6) In the above embodiment, the second conductor may have a flat plate shape along the first direction and the second direction. With such an embodiment, it is possible to suppress the occurrence of areas where the strength of the AC electric field is very weak locally with a simpler configuration.

[0091] (7) In the above embodiment, the end of the second conductor including the end in the second direction may have a shape such that, in the second direction, the distance in the first direction between it and the media gradually increases from the opposite side of the end toward the end. With such an embodiment, electric field concentration at the end of the second conductor in the second direction can be suppressed.

[0092] (8) In the above embodiment, the radius of curvature of the end of the first conductor in the second direction may be larger than the radius of curvature of the end of the first conductor in the third direction. With this embodiment, electric field concentration at the end in the longitudinal direction of the first conductor can be suppressed.

[0093] (9) In the above embodiment, the shortest distance in the first direction between the first electrode and the media may be equal to the shortest distance in the first direction between the second electrode and the media. This embodiment increases the possibility of uniform heating of the media.

[0094] (10) In the above embodiment, a third electrode may be provided, which is positioned between the first electrode and the second electrode and electrically insulated from the first electrode and the second electrode. With such an embodiment, the third electrode can reduce the variation in the strength of the electric field generated between the first electrode and the second electrode. This increases the likelihood that the media can be heated evenly.

[0095] (11) A second embodiment of the present disclosure provides a liquid dispensing system comprising a dielectric heating device as described above and a liquid dispensing unit for applying a liquid to a medium.

[0096] (12) According to a third embodiment of the present disclosure, there is a liquid dispensing device for dispensing a liquid heated by the electrode unit onto the medium, the electrode unit having a first electrode and a second electrode facing a medium in a first direction to which an alternating voltage is applied, wherein the second electrode is arranged to surround the first electrode when viewed along the first direction, and the first electrode has a first conductor and a second conductor protruding from the first conductor toward the medium, and when projected onto a plane perpendicular to the first direction, the second conductor is covered by the first conductor. The liquid dispensing device comprises a transport unit for transporting the medium, a liquid dispensing unit for dispensing the liquid onto the medium, and a dispensing control unit for controlling the transport unit and the liquid dispensing unit. [Explanation of Symbols]

[0097] 20, 20b, 20c, 20d, 20e, 20f, 20p... Electrode unit, 21... First electrode unit row, 22... Second electrode unit row, 30, 30b, 30c, 30d, 30e... First electrode, 30p... Electrode, 31... First conductor, 32, 32b, 32c... Second conductor, 33... First end, 34... Second end, 35... Intermediate part, 36... One end, 37... One end, 38... Other end, 3 9...Other end, 40...Second electrode, 50...Coil, 55...Electric wire, 56...Connecting member, 80...Voltage application part, 90...Third electrode, 100...Dielectric heating device, 110...Substrate, 180...Second control unit, 200...Liquid discharge system, 205...Liquid discharge device, 210...Liquid discharge unit, 250...First control unit, 320...Conveying unit, 321...First conveying unit, 322...Second conveying unit, 323...Roller

Claims

1. A transport unit that transports media, An electrode unit having a first electrode and a second electrode facing the medium in a first direction to which an AC voltage is applied, and heating the medium by a dielectric heating method, The system comprises a control unit for controlling the transport unit, The second electrode is positioned so as to surround the first electrode when viewed along the first direction. The first electrode comprises a first conductor and a second conductor protruding from the first conductor toward the medium. A dielectric heating device wherein, when projected onto a plane perpendicular to the first direction, the second conductor is covered by the first conductor.

2. A dielectric heating apparatus according to claim 1, A dielectric heating device wherein the first conductor and the second conductor have an elongated shape, when viewed along the first direction, having a longitudinal direction along a second direction perpendicular to the first direction and a short direction along a third direction perpendicular to both the first and second directions.

3. A dielectric heating apparatus according to claim 2, A dielectric heating device wherein the second conductor has, in the first direction, a first end connected to the first conductor, a second end opposite to the first end, and an intermediate portion disposed between the first end and the second end, with a width in the third direction that is wider than the first end and the second end.

4. A dielectric heating apparatus according to claim 3, A dielectric heating device in which, when projected onto a plane perpendicular to the first direction, the first end and the second end are covered by the intermediate portion.

5. A dielectric heating apparatus according to claim 4, A dielectric heating device wherein the second conductor has a cross shape when viewed along the second direction.

6. A dielectric heating apparatus according to claim 2, The dielectric heating device wherein the second conductor has a flat plate shape along the first direction and the second direction.

7. A dielectric heating apparatus according to claim 2, A dielectric heating device wherein one end of the second conductor, including one end in the second direction, has a shape such that, in the second direction, the distance in the first direction between it and the media gradually increases from the opposite side of the end toward the end.

8. A dielectric heating apparatus according to claim 2, A dielectric heating device wherein the radius of curvature of the end of the first conductor in the second direction is greater than the radius of curvature of the end of the first conductor in the third direction.

9. A dielectric heating apparatus according to claim 1, A dielectric heating device wherein the shortest distance in the first direction between the first electrode and the media is equal to the shortest distance in the first direction between the second electrode and the media.

10. A dielectric heating apparatus according to claim 1, A dielectric heating device comprising a third electrode positioned between the first electrode and the second electrode and electrically insulated from the first electrode and the second electrode.

11. A dielectric heating apparatus according to any one of claims 1 to 10, A liquid dispensing system comprising a liquid dispensing unit for applying liquid to the aforementioned medium.

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