Liquid spraying device

Abstract

The present invention provides a liquid ejection device capable of improving printing quality. An AC electric field generator includes: a first electrode and a second electrode, which are arranged adjacent to each other; a high-frequency voltage generator that generates a high-frequency voltage for the first and second electrodes; and a conductor that electrically connects the first and second electrodes to the high-frequency voltage generator. A carriage carrying a liquid ejection head reciprocates. The first and second electrodes are mounted on the carriage so as to face a support portion. The surface of the support portion facing the liquid ejection head, the first electrode, and the second electrode is formed of an insulator.

Description

Technical Field

[0001] The present invention relates to a liquid ejecting device including a liquid ejecting head for ejecting liquid such as ink onto a medium such as paper. Background Art

[0002] For example, Patent Document 1 discloses a liquid ejection device, such as an inkjet printer, that prints by ejecting liquids such as ink onto a medium such as paper. This liquid ejection device is equipped with a function that generates an AC electric field by applying a high-frequency voltage to alternating anodes and cathodes to inductively heat the liquid ejected onto the medium, thereby drying the medium. This function prevents degradation of print quality, such as bleeding of the liquid due to, for example, varying degrees of dryness of the medium onto which the liquid is ejected.

[0003] However, although the liquid ejecting device described in Patent Document 1 performs induction heating on the liquid ejected onto the medium, it is desired to further improve the heating efficiency of the liquid ejected onto the medium by effectively transmitting the generated alternating electric field to the liquid ejected onto the medium, for example, in order to suppress the reduction in printing quality or achieve higher quality printing.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-119395 Summary of the Invention

[0005] The liquid ejection device for solving the above-mentioned problems comprises: a supporting portion, which supports a medium; a liquid ejection head, which ejects liquid onto the medium supported on the supporting portion; a slide, which carries the liquid ejection head; an AC electric field generating portion, which generates an AC electric field, and the AC electric field generating portion has: a first electrode and a second electrode, which are arranged adjacent to each other; a high-frequency voltage generating portion, which generates a high-frequency voltage to the first electrode and the second electrode; a conductor, which electrically connects the first electrode and the second electrode to the high-frequency voltage generating portion, the slide moves back and forth, the first electrode and the second electrode are carried on the slide in a manner facing the supporting portion, and the surface of the supporting portion facing the liquid ejection head, the first electrode and the second electrode is composed of an insulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic side sectional view showing the printing system in the first embodiment.

[0007] Figure 2 It is a schematic side sectional view showing the liquid ejecting device in the first embodiment.

[0008] Figure 3It is a schematic bottom view showing the carriage in the first embodiment.

[0009] Figure 4 It is a perspective view showing the generator in the first embodiment.

[0010] Figure 5 A schematic diagram showing a wiping mechanism.

[0011] Figure 6 A block diagram showing the electrical structure of a liquid ejection device.

[0012] Figure 7 A block diagram showing the electrical structure of a liquid ejection device.

[0013] Figure 8 A flowchart showing monitoring processing.

[0014] Figure 9 It is a schematic side sectional view showing a liquid ejecting device in a third embodiment.

[0015] Figure 10 It is a perspective view showing a generator in a fourth embodiment.

[0016] Figure 11 It is a perspective view showing a generator in a fifth embodiment.

[0017] Figure 12 A schematic bottom view of the slide is shown. DETAILED DESCRIPTION

[0018] Hereinafter, one embodiment of a printing system including a liquid ejecting device will be described with reference to the drawings.

[0019] First embodiment

[0020] like Figure 1 As shown, in the first embodiment, the printing system 11 includes a holding device 12 , a winding device 13 , and a liquid ejecting device 14 .

[0021] The holding device 12 is a device for holding the roll body 100 on which the medium 99 is wound. The holding device 12 has a holding shaft 17 for holding the roll body 100. The holding shaft 17 is, for example, configured to be rotatable. As the holding shaft 17 rotates, the medium 99 is unwound from the roll body 100. In the first embodiment, the holding shaft 17 does not rotate actively, but rotates together with the roll body 100, for example, by pulling the medium 99 from the roll body 100. The medium 99 is, for example, a thin sheet such as paper or cloth. The holding shaft 17 may also be a non-rotating structure. In this case, the roll body 100 rotates relative to the holding shaft 17 by pulling the medium 99 from the roll body 100.

[0022] The winding device 13 is a device that rewinds the medium 99 unwound from the holding device 12. The winding device 13 includes a winding shaft 18 for rewinding the medium 99. The winding shaft 18 is rotatable. The winding shaft 18 rewinds the medium 99 as it rotates. As a result, the winding shaft 18 holds a roll 100 formed by rewinding the medium 99. In the first embodiment, the rotation of the winding shaft 18 unwinds the medium 99 from the roll 100 held by the holding shaft 17.

[0023] The medium 99 is transported by being taken up by the take-up device 13. The medium 99 is transported from the holding device 12 toward the take-up device 13. In the first embodiment, the direction from the holding device 12 toward the take-up device 13 is the transport direction Y of the medium 99. The medium 99 has a front surface 99A and a back surface 99B opposite to the front surface 99A.

[0024] The liquid ejection device 14 is a device that prints on the medium 99. For example, the liquid ejection device 14 is an inkjet printer that prints images such as text, photos, and graphics by ejecting ink, an example of a liquid, onto the medium 99. The liquid ejection device 14 is located between the holding device 12 and the winding device 13 in the conveyance direction Y.

[0025] The liquid ejecting device 14 includes a support unit 21 , a printing unit 22 , and a control unit 23 . The control unit 23 controls at least various components of the liquid ejecting device 14 .

[0026] The support portion 21 is, for example, a plate-shaped member, but may also be a tape coated with an adhesive material or an electrostatically attracted belt. The support portion 21 supports the medium 99 being conveyed. In the first embodiment, the support portion 21 supports the medium 99 from below. In the first embodiment, the support portion 21 is in contact with the back surface 99B of the medium 99.

[0027] In the first embodiment, the support portion 21 has a surface 21A that is opposite to the printing portion 22 in the vertical direction Z. In the first embodiment, at least the surface 21A of the support portion 21 is composed of an insulator. To give a specific example, it is preferred that the surface 21A of the support portion 21 is an insulator with a density of 0.0001S / m or less. The surface 21A of the support portion 21 is processed to form an aluminum oxide coating, but is not limited to this. For example, an insulating coating may be formed by applying an insulating material. In addition, for example, the support portion 21 itself may also be made of an insulating material. In addition, the surface 21A of the support portion 21 only needs to be an insulator in the area opposite to the printing portion 22, and whether other areas are insulators is optional.

[0028] The printing unit 22 faces the support unit 21 in the vertical direction Z. In the first embodiment, the printing unit 22 is located above the support unit 21. The printing unit 22 is configured to print on the medium 99.

[0029] like Figure 1 as well as Figure 2 As shown, in the first embodiment, the printing unit 22 includes a carriage 31 , a liquid ejecting head 32 , a drying unit 33 , an air blowing mechanism 34 , and an optical sensor 35 .

[0030] The carriage 31 carries a liquid ejection head 32, a drying section 33, an air supply mechanism 34, and an optical sensor 35. The carriage 31 is opposed to the support section 21 in the vertical direction Z. In the first embodiment, the carriage 31 is located above the support section 21. The carriage 31 scans the transported medium 99. That is, the carriage 31 moves back and forth across the width of the medium 99 above the support section 21. At this time, the carriage 31 moves back and forth in the width direction X of the medium 99. Thus, in the first embodiment, the width direction X is the scanning direction of the carriage 31. In the first embodiment, the liquid ejection device 14 is a serial printer in which the liquid ejection head 32 scans the medium 99.

[0031] The width direction X refers to two directions, including a first width direction X1 and a second width direction X2. The first width direction X1 is opposite to the second width direction X2. The width direction X is different from the conveying direction Y and the vertical direction Z, and is perpendicular to them.

[0032] In the first embodiment, the carriage 31 has a facing surface 31A. The facing surface 31A of the carriage 31 faces the support portion 21. The carriage 31 has a protrusion 31B. The protrusion 31B protrudes downward from the facing surface 31A at an outer edge 31C of the facing surface 31A of the carriage 31. The distance D1 from the top surface 31D of the protrusion 31B to the surface 21A of the support portion 21 is preferably 1 mm to 20 mm to prevent a user's fingers, etc., from entering between the facing surface 31A of the carriage 31 and the surface 21A of the support portion 21.

[0033] The liquid ejecting head 32 is mounted on the facing surface 31A of the carriage 31. The liquid ejecting head 32 faces the support portion 21 in the vertical direction Z. In the first embodiment, the liquid ejecting head 32 is located above the support portion 21. Thus, the liquid ejecting head 32 is mounted on the carriage 31 so as to face the support portion 21.

[0034] The liquid ejection head 32 includes a nozzle plate formed with nozzles for ejecting liquid. The liquid ejection head 32 ejects liquid onto the medium 99 supported by the support portion 21. As a result, an image is printed on the medium 99. In the first embodiment, the liquid ejection head 32 ejects liquid onto the surface 99A of the medium 99. The liquid ejected by the liquid ejection head 32 is, for example, an aqueous ink using water as a solvent.

[0035] When the liquid ejection head 32 ejects liquid onto the medium 99 , the amount of water contained in the medium 99 increases. That is, the liquid ejection head 32 ejects liquid onto the medium 99 to thereby increase the amount of water contained in the medium 99 .

[0036] The drying unit 33 is mounted on the facing surface 31A of the carriage 31. The drying unit 33 includes an AC electric field generating unit 41 and a cover 42. The AC electric field generating unit 41 faces the support unit 21 in the vertical direction Z. In other words, the AC electric field generating unit 41 faces the medium 99 supported by the support unit 21 in the vertical direction Z. In the first embodiment, the AC electric field generating unit 41 is located above the support unit 21.

[0037] The AC electric field generating unit 41 generates an AC electric field. In the first embodiment, the AC electric field generating unit 41 applies a treatment to the medium 99 by generating an AC electric field to heat the moisture contained in the medium 99, thereby reducing the amount of moisture contained in the medium 99. In other words, the AC electric field generating unit 41 can heat the liquid sprayed onto the medium 99 supported by the support unit 21, thereby drying the medium 99.

[0038] In the first embodiment, the AC electric field generating unit 41 heats the liquid by generating an AC electric field at 2.4 GHz, but the present invention is not limited thereto. For example, high-frequency induction heating by generating an AC electric field at 3 MHz to 300 MHz or microwave heating by generating an AC electric field at 300 MHz to 30 GHz may also be used. Among these, generating an AC electric field at 10 MHz to 20 GHz is also preferred.

[0039] like Figure 3 As shown, the AC electric field generating unit 41 includes a plurality of generators 43 for generating an AC electric field. The plurality of generators 43 are arranged across multiple rows so as to surround the liquid ejection head 32 on both sides in the width direction X and downstream in the conveyance direction of the medium 99. The plurality of generators 43 are arranged inwardly of the outer periphery of the carriage 31 so that the generated AC electric field does not affect the exterior of the carriage 31.

[0040] Furthermore, an electric field detection sensor 36 is mounted on the carriage 31. In the first embodiment, the electric field detection sensor 36 is configured to include a pair of electric field detection antennas that detect an AC electric field. The electric field detection sensor 36 faces the support portion 21 in the vertical direction Z. The electric field detection sensor 36 is positioned at an end of the carriage 31. Specifically, one of the pair of electric field detection antennas is positioned at a corner of the carriage 31 when viewed from the facing surface 31A. The other of the pair of electric field detection antennas is positioned at a corner of the carriage 31 diagonally opposite the corner of the carriage 31 where the one electric field detection antenna is positioned when viewed from the facing surface 31A. Therefore, while the pair of electric field detection antennas are positioned diagonally on the carriage 31, this is not the only option. Thus, the electric field detection sensor 36 is positioned so that the electric field detection antennas are separated from the generator 43 and detects changes in the AC electric field generated by the AC electric field generating unit 41. In the first embodiment, the electric field detection sensor 36 corresponds to an example of a detection unit.

[0041] like Figure 4 As shown, the generator 43 includes a first electrode 51, a second electrode 52, and a conductor 53. The first electrode 51 is a rectangular flat plate when viewed from above. The first electrode 51 is opposite to the support portion 21. The first electrode 51 is located above the support portion 21. The second electrode 52 is a hollow rectangular flat plate that surrounds the first electrode 51 when viewed from above. The second electrode 52 is opposite to the support portion 21. The second electrode 52 is located above the support portion 21. In this way, the first electrode 51 and the second electrode 52 are arranged adjacent to each other. In addition, the first electrode 51 and the second electrode 52 are mounted on the carriage 31 so as to face the support portion 21.

[0042] The conductor 53 electrically connects the first electrode 51 and the second electrode 52 to a high-frequency voltage generating unit 61 that generates a high-frequency voltage. The conductor 53 includes a coaxial cable 54 and a coil 55. The coaxial cable 54 includes an inner conductor 54A and an outer conductor 54B. The inner conductor 54A is connected to the first electrode 51 via the coil 55, thereby electrically connecting the high-frequency voltage generating unit 61 to the first electrode 51. The outer conductor 54B is connected to the second electrode 52, thereby electrically connecting the high-frequency voltage generating unit 61 to the second electrode 52. The coil 55, which is an example of a winding wire, is connected between the first electrode 51 and the inner conductor 54A of the coaxial cable 54 and is preferably located as close to the first electrode 51 as possible.

[0043] The minimum separation distance between the first electrode 51 and the second electrode 52 is less than one-tenth of the wavelength of the AC electric field output from the AC electric field generator 41. This allows the vast majority of the AC electric field generated when a high-frequency voltage is applied to be attenuated near the first and second electrodes 51, 52. This reduces the intensity of electromagnetic waves reaching distant locations from the first and second electrodes 51, 52. In other words, the AC electric field generated by the AC electric field generator 41 is very strong near the first and second electrodes 51, 52, but very weak at distant locations.

[0044] Such a generator 43 generates the AC electric field in a concentrated manner in a range near the first electrode 51 and the second electrode 52, for example, within a range of 3 mm to 3 cm, by appropriately controlling the frequency band of the generated AC electric field, thereby making it less likely to be affected by the AC electric field beyond this range.

[0045] like Figure 1 as well as Figure 2 As shown, in the first embodiment, the cover 42 is mounted on the carriage 31. In the first embodiment, the cover 42 is located below the AC electric field generating unit 41. In the first embodiment, the cover 42 covers the AC electric field generating unit 41 from below so that foreign matter does not adhere to the AC electric field generating unit 41. In particular, even when the liquid ejected from the liquid ejection head 32 becomes mist, in the first embodiment, the cover 42 covers the AC electric field generating unit 41 from below so that the liquid does not adhere to the AC electric field generating unit 41. Thus, in the first embodiment, the cover 42 is mounted on the carriage 31 in such a manner as to cover the generator 43 of the AC electric field generating unit 41 between the AC electric field generating unit 41 and the support portion 21.

[0046] In the first embodiment, the cover 42 is formed of a material that allows the AC electric field generated by the AC electric field generator 41 to pass through. As a specific example, the cover 42 can be formed of glass, but this is not limiting. For example, the cover 42 can also be formed of a permeable resin such as a cyclic olefin copolymer. Preferably, the material is less susceptible to induction heating. In the first embodiment, the surface of the cover 42 has a concave and convex shape, which can converge the AC electric field generated by the AC electric field generator 41 toward the medium 99 supported by the support 21.

[0047] Especially in the first embodiment, the cover 42 is preferably made of a material selected from the viewpoints of liquid adhesion, liquid cleanliness, and strength. Regarding its thickness and transmittance of the AC electric field, various materials can be used by changing the frequency and configuration of the AC electric field generating unit 41.

[0048] The drying section 33 includes an adjustment mechanism 44 that can move the generator 43 and cover 42 of the AC electric field generating section 41 in the vertical direction Z. As a result, the drying section 33 can adjust the distance between the AC electric field generating section 41 and the medium 99. The adjustment mechanism 44 can be, for example, a connecting rod mechanism or a rack and pinion mechanism. Therefore, the distance between the AC electric field generating section 41 and the medium 99 can be adjusted based on the type of medium 99, the type of liquid ejected from the liquid ejection head 32, and the like. Thus, in the first embodiment, the adjustment mechanism 44 changes the distance between the first electrode 51 and the second electrode 52 in the generator 43 relative to the support section 21. In the first embodiment, the adjustment mechanism 44 serves as an example of a changing section.

[0049] like Figure 2 As shown, the air blowing mechanism 34 is mounted on the carriage 31. The air blowing mechanism 34 includes a first duct 34A, a second duct 34B, a first blower 34C, and a second blower 34D.

[0050] The first channel 34A is a channel extending between the generator 43 and the outer edge portion 31C of the carriage 31 so as to be adjacent to the generator 43 in the vertical direction Z. The second channel 34B is a channel extending between the liquid ejection head 32 and the generator 43 so as to be adjacent to the generator 43 in the vertical direction Z. The first channel 34A and the second channel 34B are not only provided downstream of the liquid ejection head 32 in the conveyance direction Y of the medium 99, but are also provided on both sides in the width direction X of the medium 99.

[0051] The first blower 34C is located at the upper end of the first duct 34A. The first blower 34C is a fan that blows air from the outside of the carriage 31 into the first duct 34A. The second blower 34D is located at the upper end of the second duct 34B of the carriage 31. The second blower 34D is a fan that blows air from the second duct 34B to the outside of the carriage 31.

[0052] In this manner, air is supplied from the outside of the carriage 31 to the first passage 34A by driving the first blower 34C, and air is supplied from the second passage 34B to the outside of the carriage 31 by driving the second blower 34D. Consequently, below the cover 42, gas flows from the outer edge portion 31C toward the liquid ejection head 32. In the air supply mechanism 34 located downstream of the liquid ejection head 32 in the conveyance direction Y, gas flows from downstream to upstream in the conveyance direction Y of the medium 99 below the cover 42. In the air supply mechanism 34 located outward of the liquid ejection head 32 in the width direction X, gas flows from the outside to the inside in the width direction X below the cover 42. Therefore, even if the liquid ejected from the liquid ejection head 32 forms a mist, adhesion of the mist to the cover 42 can be suppressed.

[0053] Thus, in the first embodiment, the first blower 34C blows air toward the generator 43, represented by the coil 55, the first electrode 51, and the second electrode 52. This cools the generator 43. Conversely, the air sent to the first blower 34C passes through the generator 43 and is heated. The heated air is then blown toward the medium 99 on the support portion 21. As a result, the liquid sprayed onto the medium 99 is heated, accelerating the drying of the medium 99.

[0054] In the vertical direction Z, a distance D2 between the surface 21A of the support portion 21 and the first and second blowers 34C, 34D is greater than a distance D3 between the surface 21A of the support portion 21 and the generator 43 represented by the coil 55, the first electrode 51, and the second electrode 52. In the first embodiment, the first and second blowers 34C, 34D correspond to an example of an air supply unit.

[0055] like Figure 1 as well as Figure 2 As shown, the optical sensor 35 is mounted on the outer peripheral surface of the carriage 31. Although in the first embodiment, the optical sensor 35 is mounted on the outer peripheral surface facing upstream in the conveying direction Y, the outer peripheral surface facing downstream in the conveying direction Y, the outer peripheral surface facing the first width direction X1 in the width direction X, and the outer peripheral surface facing the second width direction X2 in the width direction X relative to the carriage 31, the present invention is not limited thereto.

[0056] The optical sensor 35 is positioned opposite the support portion 21. The optical sensor 35 is located above the support portion 21. The optical sensor 35 irradiates light downward. In other words, the optical sensor 35 irradiates light toward the support portion 21. The optical sensor 35 receives reflected light and detects the intensity of the received light. The intensity of the light detected by the optical sensor 35 differs depending on whether a user's finger, etc., is between the optical sensor 35 and the support portion 21 or not. Thus, based on the detection results of the optical sensor 35, it is possible to detect whether a user's finger, etc., has entered between the optical sensor 35 and the support portion 21.

[0057] like Figure 5 As shown, the liquid ejection device 14 includes a wiping mechanism 39. The wiping mechanism 39 wipes off liquid and the like adhering to the liquid ejection head 32 and the cover 42. The wiping mechanism 39 is arranged at the initial position of the carriage 31 so as to be opposed to the opposing surface 31A of the carriage 31. The liquid ejection head 32 and the cover 42 are arranged on the opposing surface 31A of the carriage 31. Therefore, the wiping mechanism 39 is arranged at the initial position of the carriage 31 so as to be opposed to the liquid ejection head 32 and the cover 42. The initial position HP of the carriage 31 is the position at one end of the moving range of the carriage 31 and is the position where the carriage 31 is on standby.

[0058] The wiping mechanism 39 includes a wiper 45 and a moving mechanism 46. The wiper 45 wipes the surface of the liquid ejection head 32 and the surface of the cover 42. The wiper 45 is made of a resin such as rubber or elastomer, but is not limited thereto. For example, it may be made of cloth. The moving mechanism 46 moves the wiper 45 back and forth. The wiper 45 is driven by the moving mechanism 46 to move back and forth in a manner of wiping the surface of the liquid ejection head 32 and the surface of the cover 42 that are stationary at the initial position HP, and moves relative to the liquid ejection head 32 and the cover 42. Thus, the wiper 45 can remove the liquid attached to the surface of the liquid ejection head 32 and the surface of the cover 42, and can form a waterproof film on the surface of the cover 42.

[0059] Next, the electrical structure of the liquid ejection device 14 will be described.

[0060] like Figure 6As shown, the liquid ejection device 14 includes a control unit 23. In the first embodiment, the control unit 23 can be configured as a circuit comprising: α: one or more processors that execute various processes according to a computer program; β: one or more dedicated hardware circuits, such as application-specific integrated circuits, that execute at least some of the various processes; or γ: a combination thereof. The processor includes a CPU and memory such as RAM and ROM, which stores program code or instructions configured to enable the CPU to execute processes. Memory, i.e., computer-readable media, includes any computer-readable media that can be accessed by a general-purpose or special-purpose computer.

[0061] The control unit 23 is electrically connected to the optical sensor 35, the electric field detection sensor 36, and the communication unit 37. In the first embodiment, the control unit 23 receives a signal from the optical sensor 35. In the first embodiment, the control unit 23 receives a signal from the electric field detection sensor 36.

[0062] In the first embodiment, the control unit 23 is configured to communicate with a terminal device (not shown) via the communication unit 37. The control unit 23 receives signals from the terminal device or sends signals to the terminal device as needed. In the first embodiment, when instruction information such as a print job is input from the terminal device, the control unit 23 executes processing corresponding to the instruction information and outputs result information such as the execution result to the terminal device. The liquid ejection device 14 may also include an operation unit that can be operated by the user and a display unit that displays various information.

[0063] In the first embodiment, the control unit 23 is configured to be able to communicate with the holding device 12 and the winding device 13 via the communication unit 37. The control unit 23 receives signals from the holding device 12 and the winding device 13, or sends signals to the holding device 12 and the winding device 13 as needed. In this way, the control unit 23 can perform overall control of the printing system 11.

[0064] The control unit 23 is electrically connected to the printing unit 22 , the carriage motor 38 , the AC electric field generating unit 41 , the air blowing mechanism 34 , and the wiping mechanism 39 .

[0065] In the first embodiment, the control unit 23 outputs a signal to the printing unit 22 based on the print image data, instructing the printing unit 22 to eject liquid and print. In the first embodiment, the control unit 23 outputs a signal to the carriage motor 38 for causing the carriage 31 to move back and forth in the width direction X. In the first embodiment, the control unit 23 outputs a signal related to the drive of the AC electric field generating unit 41 to the AC electric field generating unit 41. In the first embodiment, the control unit 23 inputs a signal from the AC electric field generating unit 41. In the first embodiment, the control unit 23 outputs a signal to the air supply mechanism 34 for driving the first blower 34C and the second blower 34D. In the first embodiment, the control unit 23 outputs a signal to the wiping mechanism 39 for driving the wiping mechanism 39.

[0066] The control unit 23 includes a monitoring unit 23A and a limiting unit 23B. The monitoring unit 23A monitors whether a limiting condition for limiting the operation of at least the AC electric field generating unit 41 is satisfied based on signals from the optical sensor 35, the electric field detection sensor 36, and the AC electric field generating unit 41. The limiting unit 23B, based on the monitoring results of the monitoring unit 23A, limits the operation of at least the AC electric field generating unit 41 when the limiting condition is satisfied. The control unit 23 includes a storage unit 23C, which includes ROM and RAM as memory. The storage unit 23C stores various data, including the program PR.

[0067] In addition, if Figure 7 As shown, the AC electric field generating unit 41 includes a generator 43 , a high-frequency voltage generating unit 61 , and a monitoring circuit 62 .

[0068] The high-frequency voltage generator 61 is connected to the generator 43. Specifically, the high-frequency voltage generator 61 is connected to the first electrode 51 and the second electrode 52 via the conductor 53. The high-frequency voltage generator 61 generates a high-frequency voltage to the first electrode 51 and the second electrode 52, and generates an AC electric field from the first electrode 51 and the second electrode 52 by outputting the high-frequency voltage to the first electrode 51 and the second electrode 52.

[0069] The high-frequency voltage generating unit 61 includes a high-frequency voltage generating circuit 63 and an amplifier circuit 64. The high-frequency voltage generating circuit 63 is connected to the control unit 23 and the amplifier circuit 64. The high-frequency voltage generating circuit 63 generates a high-frequency voltage based on a generation instruction signal from the control unit 23 and outputs it to the amplifier circuit 64. The amplifier circuit 64 amplifies the high-frequency voltage generated by the high-frequency voltage generating circuit 63 based on the generation instruction signal from the control unit 23 and outputs it to the generator 43. In the first embodiment, the high-frequency voltage generating unit 61 supplies power of 3 kW or less to the generator 43, for example, but this is not limited to this.

[0070] The monitoring circuit 62 is connected to the high-frequency voltage generating unit 61 and the control unit 23. The monitoring circuit 62 monitors the high-frequency voltage from the high-frequency voltage generating unit 61 and outputs the monitoring result of the high-frequency voltage to the control unit 23.

[0071] The monitoring circuit 62 includes a rectifier circuit 65 and a comparison circuit 66. The rectifier circuit 65 is connected to the high-frequency voltage generator 61 and the comparison circuit 66. The rectifier circuit 65 rectifies and smoothes the high-frequency voltage from the high-frequency voltage generator 61 to convert it into direct current and outputs it to the comparison circuit 66.

[0072] Comparator circuit 66 is connected to rectifier circuit 65 and controller 23. Comparator circuit 66 compares the signal output from rectifier circuit 65 with a reference voltage, and outputs a signal indicating the excess to controller 23 when the signal output from rectifier circuit 65 exceeds the reference voltage.

[0073] In the first embodiment, the monitoring circuit 62 monitors the high-frequency voltage input to the generator 43, utilizing the characteristic that abnormal heating of the coil 55 causes changes in the resistance, or impedance, of the coil 55. When the high-frequency voltage exceeds a reference voltage, it infers that the temperature of the coil 55 has risen, and detects abnormal heating associated with the generator 43. In particular, heating of the coil 55 can sometimes cause the temperature of the generator 43 to rise. By understanding the temperature fluctuations of the coil 55, abnormal heating of the generator 43 can be detected. Specifically, in the first embodiment, the coil 55 is made of copper. Copper's resistance changes significantly with temperature, and a temperature increase of approximately 50°C can be detected even with a simple circuit.

[0074] Although, in the first embodiment, the monitoring circuit 62 uses a diode for rectification and a capacitor for smoothing in the rectifier circuit 65, and a Zener diode for generating a reference voltage in the comparator circuit 66, these are not limiting. Furthermore, even if the frequency of the AC electric field generated by the generator 43 changes over time, for example, the resistance of the generator 43, particularly the resistance of the coil 55, changes, allowing the monitoring circuit 62 to detect abnormalities associated with the generator 43. In the first embodiment, the monitoring circuit 62 detects changes in the impedance of the generator 43, which includes the conductor 53, the first electrode 51, and the second electrode 52, and detects the temperature of at least one of the conductor 53, the first electrode 51, and the second electrode 52 based on the detected changes. In the first embodiment, the monitoring circuit 62 serves as an example of a detection unit and a temperature detection unit.

[0075] In the first embodiment, the control unit 23 stops printing if a restriction condition is satisfied when starting printing. After printing starts, the control unit 23 stops printing if a restriction condition is satisfied during printing. This restriction condition is established based on a signal from the monitoring circuit 62 and signals from the optical sensor 35 and the electric field detection sensor 36.

[0076] The following describes the printing process executed by the control unit 23. In the first embodiment, the control unit 23 executes the printing process when the liquid ejection device 14 is powered on and a print job is input via the communication unit 37. In the first embodiment, the print job includes the print image data to be printed, the resolution of the print image, and other information.

[0077] During printing, the control unit 23 sends a signal based on print image data to the printing unit 22, causing liquid to be ejected from the liquid ejection head 32. The control unit 23 also sends a signal to the AC electric field generator 41, driving the AC electric field generator 41 to generate an AC electric field. The control unit 23 also sends a signal to the air blowing mechanism 34, driving the first blower 34C and the second blower 34D.

[0078] The control unit 23 sends a signal to the carriage motor 38, causing the carriage 31 to reciprocate in the width direction X. The control unit 23 sends a signal to the wind-up device 13 via the communication unit 37, causing the medium 99 to be conveyed at a speed corresponding to the resolution. As a result, the control unit 23 ejects liquid onto the medium 99, causing an image to be printed on the medium 99. Furthermore, the control unit 23 terminates the printing process when a printing termination condition, such as when printing of the printed image data is completed, is satisfied.

[0079] Next, refer to Figure 8 The following describes the monitoring process performed by the control unit 23. In the first embodiment, the control unit 23 performs the monitoring process at a predetermined cycle from the time a print job is input until a printing end condition is satisfied after the power of the liquid ejecting device 14 is turned on.

[0080] like Figure 8 As shown, in step S11, the control unit 23 determines whether the restriction condition is satisfied. If the control unit 23 determines that the restriction condition is not satisfied, it does not execute step S12 and ends the monitoring process. On the other hand, if the control unit 23 determines that the restriction condition is satisfied, it moves to step S12.

[0081] In the first embodiment, the restriction condition is established when a user's finger or the like is determined to be between the optical sensor 35 and the support portion 21 based on a signal from the optical sensor 35. In the first embodiment, the restriction condition is established when the AC electric field detected based on a signal from the electric field detection sensor 36 exceeds a predetermined intensity. In the first embodiment, the restriction condition is established when abnormal heating of the generator 43 is detected based on a signal from the monitoring circuit 62 of the AC electric field generating portion 41.

[0082] In step S12, the control unit 23 executes the drive restriction process and ends the monitoring process. In this process, the control unit 23 stores restriction information that restricts printing in the storage unit 23C. In the first embodiment, the restriction information is information that is deleted when the restriction condition no longer holds.

[0083] Specifically, when a restriction condition is satisfied when a print job is input, the control unit 23 stores the restriction information in the storage unit 23C, and the print termination condition is satisfied, thereby terminating the print process and preventing printing from starting. In particular, in the first embodiment, the control unit 23 does not send a signal to the high-frequency voltage generator 61 of the AC electric field generator 41, preventing the high-frequency voltage generator 61 from starting to generate a high-frequency voltage.

[0084] If a restriction condition is met during printing, the control unit 23 stores the restriction information in the storage unit 23C, and the printing termination condition is met, thereby terminating the printing process and pausing printing. In particular, in the first embodiment, the control unit 23 controls the process by shutting off the power supply voltage to the amplifier circuit 64 of the high-frequency voltage generator 61 of the AC electric field generator 41, thereby preventing the high-frequency voltage from being amplified. Thus, the control unit 23 stops the power supply to the amplifier circuit 64 based on the detection results of the optical sensor 35, the electric field detection sensor 36, and the monitoring circuit 62, thereby stopping the high-frequency voltage from being generated by the high-frequency voltage generator 61 to the first electrode 51 and the second electrode 52. Furthermore, the control unit 23 stops sending signals to the high-frequency voltage generator 61 of the AC electric field generator 41.

[0085] Next, the operation of the liquid ejecting device 14 will be described.

[0086] In the liquid ejection device 14, the distance between the generator 43 and the cover 42 of the AC electric field generating unit 41 and the support unit 21 can be adjusted by adjusting the adjustment mechanism 44. Thus, the distance between the generator 43 and the cover 42 of the AC electric field generating unit 41 and the support unit 21 can be adjusted to an appropriate distance according to the type of medium 99 and the type of liquid.

[0087] When a print job is input, liquid is ejected from the liquid ejection head 32 onto the medium 99 supported by the support portion 21 based on the print image data. The carriage 31 reciprocates in the width direction X. The medium 99 is transported in the transport direction Y. Thus, an image is printed on the transported medium 99.

[0088] When printing an image on the medium 99, the high-frequency voltage generator 61 outputs a high-frequency voltage to the generator 43 based on a signal from the control unit 23. The generator 43 generates an AC electric field when the high-frequency voltage is input, thereby drying the medium 99 supported by the support unit 21.

[0089] When printing an image on the medium 99, the first blower 34C and the second blower 34D are driven based on a signal from the control unit 23. As a result, air is supplied from the outside of the carriage 31 to the first duct 34A adjacent to the generator 43 of the AC electric field generating unit 41. Furthermore, air is supplied from the second duct 34B adjacent to the generator 43 of the AC electric field generating unit 41 to the outside of the carriage 31. This allows the generator 43 to dissipate heat. The gas heated by the generator 43 is blown toward the medium 99 on the support portion 21. As a result, the liquid ejected onto the medium 99 is heated, thereby accelerating the drying of the medium 99. Furthermore, below the cover 42, the gas flows from the outer edge portion 31C toward the liquid ejection head 32. Therefore, it is possible to prevent the liquid ejected from the liquid ejection head 32 from becoming mist and adhering to the cover 42.

[0090] The carriage 31 has a protrusion 31B that prevents a user's finger or the like from entering between the carriage 31 and the support portion 21. Furthermore, based on a signal from the optical sensor 35, it is possible to detect the entry of a user's finger or the like between the carriage 31 and the support portion 21. When the entry of a user's finger or the like between the carriage 31 and the support portion 21 is detected, control is performed so that at least the AC electric field generating unit 41 is not generated.

[0091] An electric field detection sensor 36 is disposed on the carriage 31 at a position separated from the generator 43. When the AC electric field generated by the generator 43 exceeds a predetermined intensity based on a signal from the electric field detection sensor 36, control is performed so that at least the AC electric field generating unit 41 is not generated. When abnormal heating of the generator 43, represented by the coil 55, is detected based on a signal from the monitoring circuit 62 of the AC electric field generating unit 41, control is performed so that at least the AC electric field generating unit 41 is not generated.

[0092] As described above in detail, according to this embodiment, the following effects can be obtained.

[0093] (1) When an AC electric field is used to dry the liquid ejected onto the medium 99, compared to the case of using infrared rays, when, for example, an area on the medium 99 where the liquid is not ejected and the liquid content is extremely low is dried, an excessive temperature rise in that area can be suppressed, thereby suppressing degradation of the medium 99. Furthermore, the method is not limited to the medium 99, and the temperature rise and degradation of various peripheral components can be suppressed in the same manner, thereby suppressing the degradation of various peripheral components. Furthermore, there is no need to excessively arrange heat-dissipating components such as heat insulating materials and reflective plates for various peripheral components.

[0094] (2) When an AC electric field is used, the time from when the liquid ejected to the medium 99 is not dried to when it is dried, and the time from when the liquid ejected to the medium 99 is dried to when it is not dried can be shortened compared to when infrared rays are used.

[0095] (3) When using an AC electric field, compared to the case of using a halogen lamp, no components are used to ensure visual confirmation. In addition, halogen lamps use components such as quartz glass, which can reduce thermal efficiency, but AC electric fields do not use such components, thus suppressing the reduction in thermal efficiency.

[0096] (4) The AC electric field generating unit 41 is configured to include a first electrode 51 and a second electrode 52 disposed adjacent to each other, a high-frequency voltage generating unit 61 that generates a high-frequency voltage to the first and second electrodes 51 and 52, and a conductor 53 that electrically connects the first and second electrodes to the high-frequency voltage generating unit 61. This allows the AC electric field to be concentrated near the first and second electrodes 51 and 52, thereby improving the efficiency of heating the liquid ejected onto the medium 99 supported by the support unit 21 and the efficiency of drying the medium 99, thereby improving print quality. Furthermore, the AC electric field is less likely to be generated at a location separated from the first and second electrodes 51 and 52, eliminating the need for excessive components for suppressing the AC electric field. This prevents deterioration in the operating performance of the liquid ejection device 14 and an increase in the size of the liquid ejection device 14, thereby improving user safety.

[0097] (5) Furthermore, although induction heating has been conventionally employed for the liquid ejected onto the medium 99, it is desirable to further improve the efficiency of heating the liquid ejected onto the medium 99 by effectively transmitting the generated alternating electric field to the liquid ejected onto the medium 99, for example, in order to suppress degradation of printing quality and achieve higher-quality printing. Therefore, when the surface 21A of the support portion 21 facing the first electrode 51 and the second electrode 52 is formed of an insulator, an electric field can be generated in a direction closer to parallel to the surface 21A of the support portion 21 than when it is formed of a conductor. Consequently, the heating efficiency of the liquid ejected onto the medium 99 supported by the support portion 21 can be improved, and the drying efficiency of the medium 99 can be improved, thereby improving printing quality.

[0098] (6) By changing the distance between the first electrode 51 and the second electrode 52 relative to the support portion 21, the heating depth in the thickness direction of the liquid ejected onto the medium 99 can be changed according to the distance. Therefore, by changing the distance according to, for example, the thickness or material of the medium 99, the permeability of the liquid, the amount of liquid ejected into the medium 99, or the material, the liquid can be heated and dried according to the state of the medium 99, thereby improving printing quality.

[0099] To give a specific example, the distance between the generator 43 and the support portion 21 can be changed according to the type of medium 99, thereby suppressing a decrease in print quality. The type of medium 99 includes, for example, paper, cloth, a medium woven from a mixture of multiple fibers, and a medium containing functional raw materials such as silver, allowing for flexible handling depending on the type of medium. Furthermore, the medium 99 can be dried according to the degree of penetration of the liquid into the medium 99, such as after the liquid permeates the medium 99. In particular, in the past, when the medium 99 was thin paper, for example, rapid and excessive drying of the medium 99 could sometimes cause wrinkles to form on the medium 99 due to the absorption of liquid by the medium 99. Therefore, the distance between the generator 43 and the support portion 21 can be changed so that the medium 99 does not dry rapidly and excessively, thereby suppressing the formation of wrinkles on the medium 99. Furthermore, conventionally, when using a medium 99 that is constructed in multiple layers by combining multiple metal plates having different thermal expansion coefficients, for example, the medium 99 is dried after the liquid has permeated the medium 99 through multiple layers. This difference in thermal expansion coefficients may cause wrinkles in the medium 99. Therefore, by changing the distance between the generator 43 and the support portion 21 so that the liquid can be dried before the liquid has permeated the medium 99 through multiple layers, the generation of wrinkles in the medium 99 can be suppressed.

[0100] (7) By providing the cover 42 that covers the first electrode 51 and the second electrode 52, it is possible to suppress contact between the first electrode 51 and the second electrode 52 and the medium 99. Even if the liquid ejected from the liquid ejection head 32 is in the form of mist, it is possible to suppress the adherence of the misted liquid to the first electrode 51 and the second electrode 52. Therefore, it is possible to suppress a decrease in the heating efficiency of the liquid due to the adherence of the misted liquid to the first electrode 51 and the second electrode 52, thereby suppressing a decrease in the drying efficiency of the medium 99 and thus suppressing a decrease in the printing quality.

[0101] (8) By providing the wiper 45 for wiping the surface of the cover 42, even if the liquid ejected from the liquid ejection head 32 becomes mist and the misted liquid adheres to the surface of the cover 42, the liquid adhering to the surface of the cover 42 can be wiped. In addition, a waterproof film can be formed on the surface of the cover 42, making it difficult for the misted liquid to adhere to the surface of the cover 42. Therefore, it is possible to suppress the reduction in the heating efficiency of the liquid caused by the adhesion of the misted liquid to the cover 42, thereby suppressing the reduction in the drying efficiency of the medium 99, thereby suppressing the reduction in printing quality.

[0102] (9) Conventionally, for example, when drying an area with an extremely low liquid content in the medium 99, heat may easily accumulate in the first electrode 51 and the second electrode 52, and excessive heat may accumulate in the first electrode 51 and the second electrode 52. Therefore, by blowing air toward the first electrode 51 and the second electrode 52, even when heat accumulates in the first electrode 51 and the second electrode 52, heat can be dissipated from the first electrode 51 and the second electrode 52. Therefore, degradation of the first electrode 51 and the second electrode 52 due to heat can be suppressed, thereby suppressing a decrease in printing quality.

[0103] (10) Furthermore, in the vertical direction Z, i.e., the perpendicular direction, the distance D2 between the surface 21A of the support portion 21 and the first blower 34C and the second blower 34D of the air supply mechanism 34 is greater than the distance D3 between the surface 21A of the support portion 21 and the first electrode 51 and the second electrode 52. Therefore, by blowing air from the first electrode 51 and the second electrode 52 toward the support portion 21 in the vertical direction Z, the heated gas is blown toward the medium 99 supported by the support portion 21 as the first electrode 51 and the second electrode 52 dissipate heat. Therefore, the heating efficiency of the liquid ejected onto the medium 99 supported by the support portion 21 can be improved, thereby improving the drying efficiency of the medium 99 and thereby improving the printing quality.

[0104] (11) Furthermore, even if the liquid ejected from the liquid ejection head 32 becomes mist, the misted liquid can be prevented from adhering to the first electrode 51 and the second electrode 52 by blowing air in the vertical direction Z from the first electrode 51 and the second electrode 52 toward the support portion 21. Therefore, a decrease in the heating efficiency of the liquid due to the adhesion of the misted liquid to the first electrode 51 and the second electrode 52 can be suppressed, thereby suppressing a decrease in the drying efficiency of the medium 99 and thereby suppressing a decrease in the printing quality.

[0105] (12) Conventionally, for example, when drying an area of the medium where the liquid content is extremely low, heat may easily accumulate in the coil 55 included in the conductor 53, causing excessive heat to accumulate in the coil 55. Therefore, by providing an air supply mechanism 34 that supplies air to the coil 55 included in the conductor 53, even if heat accumulates in the coil 55, it is possible to dissipate heat from the coil 55. Therefore, it is possible to suppress deterioration of the coil 55 due to heat, thereby suppressing a decrease in printing quality.

[0106] (13) A monitoring circuit 62 is provided for detecting the temperature of at least one of the conductor 53, the first electrode 51, and the second electrode 52. Based on the result detected by the monitoring circuit 62, the generation of the high-frequency voltage from the high-frequency voltage generating unit 61 to the first electrode 51 and the second electrode 52 is stopped. Thus, for example, when the temperature of at least one of the conductor 53, the first electrode 51, and the second electrode 52 rises excessively, the generation of the high-frequency voltage can be stopped based on the detected temperature. Consequently, when heat accumulates in at least one of the conductor 53, the first electrode 51, and the second electrode 52, degradation due to the heat can be suppressed, thereby suppressing a decrease in printing quality.

[0107] (14) The high-frequency voltage generator 61 generates a high-frequency voltage of 10 MHz to 20 GHz. The distance between the top surface 31D of the protrusion 31B and the surface 21A of the support portion 21 is 1 mm to 20 mm. Therefore, the distance between the top surface 31D of the protrusion 31B and the surface 21A of the support portion 21 is set so that a user's finger or the like cannot enter between the first and second electrodes 51, 52, and the surface 21A of the support portion 21. Therefore, safety can be improved even when a high-frequency voltage is generated.

[0108] (15) Furthermore, conventionally, due to, for example, changes in the generated AC electric field over time or usage conditions beyond the designer's intention, there is a possibility that abnormalities may occur, such as changes in the generated AC electric field, changes in the conditions for heating the liquid ejected onto the medium 99, and excessive accumulation of heat in the first electrode 51 and the second electrode 52. Therefore, based on the result of detecting the change in the AC electric field generated by the AC electric field generating unit 41, the generation of the high-frequency voltage from the high-frequency voltage generating unit 61 to the first electrode 51 and the second electrode 52 is stopped. Thus, even in the event of abnormalities such as deformation of the first electrode 51 and the second electrode 52 over time or usage conditions beyond the designer's intention, the generation of the high-frequency voltage can be stopped based on the detected change in the AC electric field, thereby improving safety against the occurrence of abnormalities.

[0109] (16) Based on the result of detecting the temperature of any one of the conductor 53, the first electrode 51, and the second electrode 52, the generation of the high-frequency voltage from the high-frequency voltage generating unit 61 to the first electrode 51 and the second electrode 52 is stopped. Thus, even if an abnormality occurs, such as an excessive increase in the temperature of any one of the conductor 53, the first electrode 51, and the second electrode 52 due to a change over time or a usage condition not intended by the designer, the generation of the high-frequency voltage can be stopped based on the detected temperature, thereby improving safety against the occurrence of abnormalities.

[0110] (17) The electric field detection sensor 36 includes an electric field detection antenna for detecting the intensity of the AC electric field. The electric field detection antenna is disposed so as to be separated from the first electrode 51 and the second electrode 52. Therefore, changes in the AC electric field can be detected at a location separated from the first electrode 51 and the second electrode 52, such as outside the region where the liquid ejected onto the medium 99 is dried, rather than at a location near the region where the liquid ejected onto the medium 99 is not separated from the first electrode 51 and the second electrode 52. This increases the likelihood of detecting changes in the AC electric field generated by the AC electric field generating unit 41.

[0111] (18) When the high-frequency voltage generating unit 61 stops generating the high-frequency voltage to the first electrode 51 and the second electrode 52 , the high-frequency voltage generating unit 61 can be protected by stopping the power supply to the amplifier circuit 64 .

[0112] (19) By detecting changes in the impedance of the conductor 53, the first electrode 51, and the second electrode 52, it is possible to detect changes in the AC electric field generated by the AC electric field generating unit 41 before the AC electric field generated by the AC electric field generating unit 41 changes excessively. Therefore, the possibility of detecting changes in the AC electric field generated by the AC electric field generating unit 41 can be increased.

[0113] Second embodiment

[0114] Next, a second embodiment of the present invention will be described.

[0115] In the first embodiment, the AC electric field is generated in a single frequency band, but in the second embodiment, the AC electric field is selectively generated in any one of multiple frequency bands. In the following description, the same reference numerals are used for the same structures and control contents as those in the previously described embodiments, and any duplicate descriptions are omitted or simplified.

[0116] In the second embodiment, the AC electric field generator 41 selectively generates one of a plurality of high-frequency voltages having different frequencies. Specifically, the AC electric field generator 41 selectively generates one of a first frequency band AC electric field, such as 915 MHz, and a second frequency band AC electric field, such as 2.4 GHz.

[0117] In this case, AC electric field generator 41 includes a first-system generator and a high-frequency voltage generator for generating an AC electric field in a first frequency band, and a second-system generator and a high-frequency voltage generator for generating an AC electric field in a second frequency band. The first-system generator and the second-system generator are alternately arranged adjacent to each other. This reduces variations in the AC electric field intensity per unit area of dielectric 99.

[0118] When generating an AC electric field in a first frequency band, the control unit 23 controls the high-frequency voltage generator of the first system, thereby generating an AC electric field in the first frequency band from the generator of the first system. When generating an AC electric field in a second frequency band, the control unit 23 controls the high-frequency voltage generator of the second system, thereby generating an AC electric field in the second frequency band from the generator of the second system.

[0119] As described above in detail, according to this embodiment, in addition to (1) to (19) in the first embodiment, the following effects can be obtained.

[0120] (20) The AC electric field generating unit 41 selectively generates any one of a plurality of AC electric fields having different frequencies, thereby varying the heating depth in the thickness direction of the liquid ejected onto the medium 99 according to the frequency. Therefore, by varying the frequency according to, for example, the thickness or material of the medium 99, the permeability of the liquid, the ejection amount or material of the liquid ejected onto the medium 99, etc., the liquid can be heated and dried according to the state of the medium 99, thereby improving printing quality.

[0121] Third embodiment

[0122] Next, a third embodiment of the present invention will be described.

[0123] In the first embodiment, the cover 42 covering the generator 43 is fixed to the carriage 31 , but in the third embodiment, the cover 42 is movable between a first position covering the generator 43 and a second position not covering the generator 43 .

[0124] like Figure 9 As shown, in the third embodiment, the cover 42 is movably mounted on the carriage 31. The cover 42 is positioned at a second position where it does not cover the generator 43. Thus, the cover 42 is configured to be movable between a first position and a second position. Thus, by moving the cover 42 to the second position, the medium 99 can be dried using the AC electric field generated by the generator 43. In this case, the cover 42 may also be made of a material that is less permeable to the AC electric field.

[0125] The cover 42 is not limited to being positioned downstream of the liquid ejection head 32 in the transport direction Y of the medium 99; it may also be positioned on either side of the width direction X of the medium 99. For example, when the carriage 31 moves in the width direction X, the cover 42 may be configured to move in the width direction X and open and close by engaging with a locking portion in the support portion 21 or the like. Alternatively, for example, a motor may be provided to move the cover 42, and the control portion 23 may drive the motor to move the cover 42, thereby opening and closing the cover 42. In particular, a configuration may be employed in which, when liquid is ejected from the liquid ejection head 32 both when the carriage 31 moves in the first width direction X1 and when the carriage 31 moves in the second width direction X2, the cover 42 positioned in the direction of the carriage 31's movement opens, while the cover 42 positioned in the direction opposite to the carriage 31's movement closes. In this case, for example, the support portion 21 may have locking portions at both ends in the width direction X. Alternatively, the cover 42 may be locked with the locking portion of the support portion 21 in conjunction with the movement of the carriage 31 in the width direction X. The cover 42 positioned in the direction of movement of the carriage 31 may be opened, while the cover 42 positioned in the direction opposite to the direction of movement of the carriage 31 may be closed. Furthermore, the control unit 23 may selectively open and close the cover 42 to correspond to the print mode for printing an image at a resolution, etc., included in the print job.

[0126] Fourth embodiment

[0127] Next, a fourth embodiment of the present invention will be described.

[0128] In the fourth embodiment, the coil 55 is configured to deform due to thermal expansion, so that when abnormal heating of the generator 43 occurs, the coil 55 expands and the contact is disconnected.

[0129] like Figure 10 As shown, in the fourth embodiment, the generator 43 includes a coil support portion 56 that supports the coil 55. The coil support portion 56 is disposed on the upper surface of the first electrode 51. The coil support portion 56 has an opening 56A in the direction opposite to the first electrode 51.

[0130] The coil 55 is arranged so as to pass through the opening 56A. Thus, the coil 55 is supported by the coil support portion 56. The coil 55 has a contact portion 55A that contacts the contact portion 57A of the contact member 57.

[0131] The conductor 53 includes a contact member 57. The contact member 57 includes a contact portion 57A that contacts the contact portion 55A of the coil 55. The contact member 57 is connected to the inner conductor 54A of the coaxial cable 54.

[0132] When coil 55 is not abnormally heated, contact portion 55A of coil 55 contacts contact portion 57A of contact member 57, electrically connecting coil 55 and contact member 57. When coil 55 is abnormally heated, thermal expansion of coil 55 causes coil 55 to lengthen while supported on coil support portion 56. Consequently, contact portion 55A of coil 55 and contact portion 57A of contact member 57 no longer contact each other, electrically disconnecting coil 55 and contact member 57. This allows generator 43 to be configured such that no high-frequency voltage is input, thereby preventing the generation of an AC electric field.

[0133] Furthermore, a protection circuit is connected between the amplifier circuit 64 of the high-frequency voltage generating unit 61 and the generator 43. This protection circuit includes a clamp circuit. By providing this protection circuit, the coil 55 and the contact member 57 are disconnected from their electrically connected state, protecting the amplifier circuit 64 even when the amplifier circuit 64 is unloaded.

[0134] Fifth embodiment

[0135] Next, a fifth embodiment of the present invention will be described.

[0136] In the fifth embodiment, a plurality of generators 43 constituting the AC electric field generating unit 41 are connected by a flexible member such as a wire, a metal wire, or a resin rod, and tension of the connected member is detected.

[0137] like Figure 11 As shown, in the fifth embodiment, the generator 43 includes a connecting portion 58 extending from the second electrode 52 in the vertical direction Z. The connecting portion 58 includes an opening 58A at its tip. For example, the opening 58A opens in the width direction X.

[0138] A connecting member 59 is fixed to the opening 58A. The connecting member 59 is a member for connecting the plurality of generators 43 arranged in the width direction X. The connecting member 59 is fixed to each of the plurality of generators 43 arranged in the width direction X.

[0139] The liquid ejection device 14 includes a detection sensor 60 that detects the tension of the connecting member 59. Based on the signal from the detection sensor 60, the control unit 23 determines that at least one of the multiple generators 43 has displaced when the tension of the connecting member exceeds a predetermined tension, and determines that the restriction condition has been satisfied. For example, when cloth is used as the medium 99, the generator 43 may be physically displaced due to external forces applied to it, such as threads flying out of the cloth or contacting the generator 43 during printing. Even in such cases, the physical displacement of the generator 43 is detected, and the restriction condition is satisfied.

[0140] The connecting member 59 may be fixed to each of the multiple generators 43 arranged in the conveying direction Y, or to each of the multiple generators 43 arranged in the width direction X, and also to each of the multiple generators 43 arranged in the conveying direction Y. Furthermore, for example, the first electrode 51 may include a connecting portion 58. In this manner, the connecting member 59 and the detection sensor 60 are switches that are fixed to the first electrode 51 or the second electrode 52 and operate in response to displacement of the first electrode 51 or the second electrode 52. Such a connecting member 59 and the detection sensor 60 constitute an example of a detection unit.

[0141] With this configuration, it is possible to physically detect displacement of the first electrode 51 or the second electrode 52, such as deformation of the first electrode 51 or the second electrode 52 due to contact with the medium 99, which causes an excessive change in the AC electric field generated by the AC electric field generating unit 41. Therefore, the possibility of detecting changes in the AC electric field generated by the AC electric field generating unit 41 can be increased.

[0142] Furthermore, the above embodiment can be modified into the following modified examples. Furthermore, the above embodiment and the following modified examples can be appropriately combined as further modified examples, and the following modified examples can be appropriately combined with each other as further modified examples.

[0143] While the control unit 23 performs monitoring processing at a predetermined interval when printing is performed after the liquid ejecting device 14 is powered on, the present invention is not limited thereto. For example, the control unit 23 may perform monitoring processing immediately after the liquid ejecting device 14 is powered on, may perform monitoring processing thereafter, or may not perform monitoring processing at all. Furthermore, a combination of these methods is also possible.

[0144] For example, the monitoring circuit 62 may output a signal to the amplifier circuit 64 of the high-frequency voltage generating section 61 without outputting a signal to the control section 23 , thereby blocking the power supply voltage supplied to the amplifier circuit 64 .

[0145] Although the power supply voltage to the amplifier circuit 64 is cut off when an abnormality is detected, this is not limiting. For example, the power supply voltage to the high-frequency voltage generator 61 itself may be cut off. Furthermore, for example, printing by the liquid ejection device 14 itself may or may not be suspended.

[0146] Although the surface of the support portion 21 is formed of an insulator, heating efficiency can be further improved by providing a gap of approximately 5 mm between the dielectric 99 and the support portion 21. Alternatively, by providing a gap of approximately 5 mm between the dielectric 99 and the support portion 21, the surface of the support portion 21 can be formed of an insulator with even lower insulation properties.

[0147] The support portion 21 may also have a suction hole, and the liquid ejection device 14 may also have a suction fan. The suction hole of the support portion 21 is a hole that passes through the support surface of the support medium 99 and the back side of the support surface. The suction fan sucks air from the support surface to the back side through the suction hole. The control portion 23 implements control to drive the suction fan. In this case, for example, the control portion 23 may also control the suction fan in the following manner, that is, when abnormal heating of the generator 43 is detected, the suction force for sucking air from the support surface to the back side through the suction hole is increased. Thereby, the heat dissipation of the generator 43 arranged on the surface 21A of the support portion 21 can be promoted, and the drying efficiency of the medium 99 can be improved.

[0148] ·It is also possible to set it so that when there is no liquid in the medium 99, the resonant frequency of the generator 43 will change, and the monitoring circuit 62 may include a circulator for detecting the reflected wave by utilizing the characteristic that the reflected wave from the generator 43 to the high-frequency voltage generating unit 61 increases, thereby detecting whether there is liquid in the medium 99 or not.

[0149] A temperature sensor such as a thermistor or thermostat may be provided in the generator 43, and a temperature abnormality of the generator 43 may be detected based on a signal from the temperature sensor. In other words, such a temperature sensor is an example of a temperature detection unit that detects the temperature of any one of the conductor 53, the first electrode 51, and the second electrode 52.

[0150] An infrared sensor may be disposed at a position separate from the generator 43 but near the generator 43, and a temperature abnormality of the generator 43 may be detected based on a signal from the infrared sensor. Such an infrared sensor is an example of a temperature detection unit that detects the temperature of any one of the conductor 53, the first electrode 51, and the second electrode 52.

[0151] The control unit 23 may also control the AC field generating unit 41 to generate an AC field when it determines that the medium 99 having liquid ejected exists in the area facing the AC field generating unit 41, and not generate an AC field when it determines that the medium 99 having liquid ejected does not exist in the area facing the AC field generating unit 41. For example, the control unit 23 may determine that the medium 99 having liquid ejected exists in the area facing the AC field generating unit 41 by referring to the print image data and checking whether liquid has been ejected into the area facing the AC field generating unit 41. Furthermore, for example, the control unit 23 may monitor the drive signal output to the printing unit 22 based on the print image data and determine that the medium 99 having liquid ejected exists in the area facing the AC field generating unit 41 by referring to the drive signal and checking whether liquid has been ejected into the area facing the AC field generating unit 41.

[0152] While the optical sensor 35 is configured to detect the presence of a user's finger or the like between the optical sensor 35 and the support portion 21 based on the detection results, the present invention is not limited to this. For example, the optical sensor 35 may also be configured to detect deformation of the medium 99 caused by, for example, clogging of the medium 99 between the optical sensor 35 and the support portion 21. The intensity of light detected by the optical sensor 35 differs depending on whether a user's finger or the like is present between the optical sensor 35 and the support portion 21, whether the medium 99 is deformed, or whether neither of these conditions are present. Therefore, based on the detection results of the optical sensor 35, it is possible to detect the presence of a user's finger or the like between the optical sensor 35 and the support portion 21, or whether the medium 99 is deformed.

[0153] While the optical sensor 35 is mounted on the outer peripheral surface of the carriage 31, this is not limiting. For example, the carriage 31 may be mounted with the optical sensor 35 on the opposing surface 31A of the carriage 31, or may not be mounted with the optical sensor 35. Specifically, if thin paper or vinyl is used as the medium 99, the medium 99 may have a structure with the protrusion 31B without increasing its thickness. In this case, the optical sensor 35 may not be mounted.

[0154] While the carriage 31 includes a protrusion 31B that protrudes downward from the facing surface 31A, the carriage 31 is not limited thereto. For example, the carriage 31 may be configured without the protrusion 31B. Specifically, when a carpet or a wooden board is used as the medium 99, it is preferable that the medium 99 be thicker and without the protrusion 31B. Furthermore, it is preferable that the optical sensor 35 be mounted thereon.

[0155] When the optical sensor 35 is not mounted or the protrusion 31B is not provided, the distance between the first and second electrodes 51 and 52 and the support portion 21 is preferably 1 mm to 20 mm, which is too small for a user's finger or the like to enter.

[0156] Although the liquid ejecting head 32 is arranged on the same surface as the opposing surface 31A of the carriage 31, the present invention is not limited thereto. For example, the liquid ejecting head 32 may be arranged below the opposing surface 31A of the carriage 31 so as to protrude from the opposing surface 31A, or may be arranged above the opposing surface 31A of the carriage 31.

[0157] Although the cover 42 is arranged on the same surface as the facing surface 31A of the carriage 31, the present invention is not limited thereto. For example, the cover 42 may be arranged below the facing surface 31A of the carriage 31 so as to protrude from the facing surface 31A, or may be arranged above the facing surface 31A of the carriage 31.

[0158] At least one of the first blower 34C and the second blower 34D may also blow air in the opposite direction. While the first blower 34C and the second blower 34D blow air in the vertical direction Z, this is not limiting. For example, air may be blown from downstream to upstream in the conveyance direction Y of the medium 99. Neither the first blower 34C nor the second blower 34D may be provided.

[0159] The first electrode 51 may be a flat plate having a square shape when viewed from above. The second electrode 52 may not surround the first electrode 51 when viewed from above. The second electrode 52 may also be a flat plate having a square shape. In other words, the first electrode 51 and the second electrode 52 may be arranged adjacent to each other.

[0160] While the generator 43 of the AC electric field generating unit 41 is configured to adjust both the first electrode 51 and the second electrode 52 in the vertical direction Z, this is not limiting. For example, the generator 43 may be configured to adjust the angles of the first and second electrodes 51, 52. When adjusting the angles of the first and second electrodes 51, 52, either one can be moved upward or downward without moving the other, or one can be moved upward while the other is moved downward. In particular, adjustment can be performed by changing the angles of the first and second electrodes 51, 52 toward the direction in which the liquid ejection head 32 is positioned, thereby shifting the position of the medium 99 facing the first and second electrodes 51, 52 closer to the direction in which the liquid ejection head 32 is positioned, thereby shortening the distance to the medium 99 facing the first and second electrodes 51, 52. On the other hand, by changing the angle of the first electrode 51 and the second electrode 52 in the direction opposite to the direction in which the liquid ejection head 32 is disposed, the position of the medium 99 facing the first electrode 51 and the second electrode 52 can be adjusted away from the direction in which the liquid ejection head 32 is disposed, thereby increasing the distance to the medium 99 facing the first electrode 51 and the second electrode 52. By configuring the first electrode 51 and the second electrode 52 so that the angle can be adjusted, the position of the medium 99 facing the first electrode 51 and the second electrode 52 and the distance to the medium 99 facing the first electrode 51 and the second electrode 52 can be adjusted.

[0161] Although the AC electric field generating unit 41 can be adjusted in the vertical direction Z independently of the liquid ejecting head 32 , the present invention is not limited thereto. For example, the AC electric field generating unit 41 may be adjusted in the vertical direction Z in conjunction with the liquid ejecting head 32 .

[0162] The AC electric field generating unit 41 may selectively generate AC electric fields of multiple frequency bands by changing at least any one of the generator 43 such as the coil 55, the high-frequency voltage generating circuit 63 of the high-frequency voltage generating unit 61, and the amplifier circuit 64, thereby generating any one of the AC electric fields of the multiple frequency bands.

[0163] Although the AC electric field generating unit 41 includes multiple generators 43 and high-frequency voltage generating units 61, the present invention is not limited thereto. For example, the AC electric field generating unit 41 may include multiple generators 43 and a single high-frequency voltage generating unit 61 that outputs high-frequency voltage to the multiple generators 43. Furthermore, for example, the AC electric field generating unit 41 may include multiple generators 43, multiple amplifier circuits 64, and a single high-frequency voltage generating circuit 63 that outputs voltage to the multiple amplifier circuits 64.

[0164] While the high-frequency voltage generator 61 is mounted on the carriage 31, this is not limiting. For example, it may not be mounted on the carriage 31. When the high-frequency voltage generator 61 is not mounted on the carriage 31, the carriage 31 can be made lighter. On the other hand, when the high-frequency voltage generator 61 is mounted on the carriage 31, the transmission distance of the high-frequency voltage can be shortened, thereby suppressing attenuation of the high-frequency voltage and reducing power consumption.

[0165] The AC electric field generator 41 may be configured independently of the carriage 31, rather than mounted on the carriage 31. In this case, the carriage 31 can be made lighter. Furthermore, for example, when the AC electric field generator 41 is not mounted on the carriage 31 but is configured independently of the carriage 31, it may or may not move in the width direction X. By configuring the AC electric field generator 41 to be movable in the width direction X without being mounted on the carriage 31, the number of generators 43 required to form the AC electric field generator 41 can be reduced.

[0166] ·like Figure 12 As shown, for example, the generator 43 of the AC electric field generating unit 41 only needs to be arranged at an appropriate position relative to the liquid ejection head 32. As a specific example, the generator 43 can also be arranged at an appropriate position relative to the liquid ejection head 32 so that the liquid ejected onto the medium 99 is dried in stages.

[0167] The generators 43 of the AC electric field generating section 41 may be arranged in a single row relative to the liquid ejection head 32, rather than across multiple rows. For example, the generators 43 of the AC electric field generating section 41 may be arranged on one side of the liquid ejection head 32 in the width direction X, rather than on the other side in the width direction X. For example, the generators 43 of the AC electric field generating section 41 may not be arranged on both sides of the liquid ejection head 32 in the width direction X. For example, the generators 43 of the AC electric field generating section 41 may not be arranged downstream of the liquid ejection head 32 in the direction in which the medium 99 is transported.

[0168] The generator 43 of the AC electric field generating unit 41 can also be positioned upstream of the liquid ejection head 32 in the direction in which the medium 99 is transported. Conventionally, the condition of the medium 99 before liquid ejection, such as its moisture content, could cause problems such as bleeding of the liquid, which could degrade print quality. Therefore, by positioning the first and second electrodes 51, 52 upstream of the liquid ejection head 32 in the direction in which the medium 99 is transported, the medium 99 is heated and dried before being transported, allowing liquid to be ejected from the liquid ejection head 32 onto the transported medium. This allows the medium to be dried before liquid is ejected from the liquid ejection head 32 onto the medium, thereby improving print quality.

[0169] A pre-processing unit that performs pre-processing on the printed medium may be disposed upstream of the printing unit 22 in the conveyance direction of the medium 99. As a specific example, a pre-processing unit that applies a processing liquid to the medium 99 may be disposed. This pre-processing unit may be incorporated into the liquid ejecting device 14 or incorporated into the printing system 11 other than the liquid ejecting device 14.

[0170] Conventionally, the condition of the medium 99 before liquid is ejected, such as the moisture content of the medium 99 being transported, can cause problems such as bleeding of the liquid. Therefore, the processing liquid applied to the medium 99 can be heated to dry the medium 99 before the liquid is ejected from the liquid ejection head 32 onto the medium 99, thereby improving print quality.

[0171] The medium 99 is not limited to paper and may also be a film or sheet made of synthetic resin, cloth, nonwoven fabric, laminated sheet, etc. Furthermore, the medium 99 is not limited to long strips of paper such as roll paper and may be single sheets. It is also not limited to media that may wrinkle when printing is not performed properly and may be media that may curl.

[0172] The path for conveying the medium 99 is not limited to a horizontally extending path, and may be any path shape, such as a trapezoidal path in side view or a path that turns back from one conveying direction and conveys in the other conveying direction.

[0173] The liquid ejecting device 14 may include at least one of the holding device 12 and the winding device 13 .

[0174] The liquid ejecting device 14 may be configured to further dry the printed medium 99 independently of the drying unit 33 .

[0175] Hereinafter, technical ideas and effects grasped from the above-described embodiment and modified examples will be described together.

[0176] The liquid ejection device includes: a supporting portion that supports a medium; a liquid ejection head that ejects liquid onto the medium supported on the supporting portion; a slide that carries the liquid ejection head; an AC electric field generating portion that generates an AC electric field, the AC electric field generating portion having: a first electrode and a second electrode that are arranged adjacent to each other; a high-frequency voltage generating portion that generates a high-frequency voltage toward the first electrode and the second electrode; a conductor that electrically connects the first electrode and the second electrode to the high-frequency voltage generating portion, the slide moves back and forth, the first electrode and the second electrode are carried on the slide in a manner facing the supporting portion, and the surface of the supporting portion facing the liquid ejection head, the first electrode, and the second electrode is composed of an insulator.

[0177] With this configuration, when the surface of the support portion is made of an insulator, an electric field can be generated in a direction that is nearly parallel to the surface of the support portion, compared to when the surface of the support portion facing the first and second electrodes is made of a conductor. This improves the efficiency of heating the liquid ejected onto the medium supported by the support portion, thereby improving the efficiency of drying the medium and, consequently, improving print quality.

[0178] In the above-mentioned liquid ejection device, the AC electric field generating section may selectively generate any one of a plurality of AC electric fields having different frequencies.

[0179] This structure selectively generates one of multiple alternating current fields with different frequencies, thereby varying the heating depth in the thickness direction of the liquid being ejected onto the medium. Therefore, by varying the frequency based on, for example, the thickness or material (permeability) of the medium, the amount of liquid ejected onto the medium, or the material, the liquid can be heated and dried according to the medium's condition, thereby improving print quality.

[0180] The above-mentioned liquid ejection device may further include a changing unit configured to change a distance between the first electrode and the second electrode and the support portion.

[0181] According to this structure, by changing the distance between the first electrode and the second electrode and the support portion, the heating depth in the thickness direction of the liquid ejected onto the medium can be varied according to the distance. Therefore, for example, by varying the frequency based on the thickness or material (permeability) of the medium, the amount of liquid ejected onto the medium, or the material, the liquid can be heated and dried according to the medium's condition, thereby improving printing quality.

[0182] The liquid ejecting device may further include a cover that is mounted on the carriage and covers the first electrode and the second electrode between the first electrode and the second electrode and the support portion.

[0183] According to this structure, by providing a cover covering the first and second electrodes, contact between the first and second electrodes and the medium can be suppressed. Even if the liquid ejected from the liquid ejection head forms a mist, adhesion of the misted liquid to the first and second electrodes can be suppressed. Consequently, a decrease in the heating efficiency of the liquid caused by adhesion of the misted liquid to the first and second electrodes can be suppressed, thereby suppressing a decrease in the drying efficiency of the medium and, consequently, suppressing a decrease in print quality.

[0184] The liquid ejecting device may further include a wiper configured to wipe the surface of the cover.

[0185] According to this structure, by providing a wiper for wiping the surface of the cover, even if the liquid ejected from the liquid ejection head forms a mist and adheres to the cover surface, the liquid adhering to the cover surface can be wiped away. Furthermore, a waterproof film can be formed on the cover surface, making it difficult for the misted liquid to adhere to the cover surface. Therefore, a decrease in the heating efficiency of the liquid caused by the adherence of the misted liquid to the cover can be suppressed, thereby suppressing a decrease in the drying efficiency of the medium and thus suppressing a decrease in print quality.

[0186] In the above-mentioned liquid ejection device, it can also be set to include an air supply unit, which supplies air to the first electrode and the second electrode, and in the direction perpendicular to the surface of the support unit, the distance between the surface of the support unit and the air supply unit is greater than the distance between the surface of the support unit and the first electrode and the second electrode.

[0187] Conventionally, for example, when drying an area of the medium with extremely low liquid content, heat can easily accumulate in the first and second electrodes, resulting in excessive heat accumulation there. Therefore, with this configuration, by sending air to the first and second electrodes, even when heat is accumulated there, it is possible to dissipate the heat there. This prevents thermal degradation of the first and second electrodes, thereby minimizing degradation in print quality.

[0188] Furthermore, in a direction perpendicular to the surface of the support portion, the distance between the surface of the support portion and the air supply portion is greater than the distance between the surface of the support portion and the first and second electrodes. Therefore, by supplying air perpendicular to the surface of the support portion from the first and second electrodes toward the support portion, the heated air is blown toward the medium supported by the support portion as the first and second electrodes dissipate heat. This improves the heating efficiency of the liquid sprayed onto the medium supported by the support portion, thereby improving the drying efficiency of the medium and, consequently, enhancing print quality.

[0189] Furthermore, even if the liquid ejected from the liquid ejection head forms a mist, the air flow from the first and second electrodes toward the support portion in a direction perpendicular to the surface of the support portion prevents the misted liquid from adhering to the first and second electrodes. This prevents a decrease in the heating efficiency of the liquid caused by the misted liquid adhering to the first and second electrodes, thereby preventing a decrease in the drying efficiency of the medium and, consequently, preventing a decrease in print quality.

[0190] In the above-described liquid ejecting device, the conductor may include a winding wire, and the liquid ejecting device may include an air supply unit configured to supply air to the winding wire.

[0191] Conventionally, for example, when drying an area of the medium with extremely low liquid content, heat can easily accumulate in the conductor's winding wire, leading to excessive heat buildup. Therefore, with this configuration, the provision of an air supply unit that delivers air to the conductor's winding wire allows heat to be dissipated even when heat accumulates in the winding wire. This prevents thermal degradation of the winding wire and reduces the likelihood of degradation in print quality.

[0192] In the above-mentioned liquid ejection device, it can also be set to include: a control unit, which implements control of the AC electric field generating unit; a temperature detection unit, which detects the temperature of at least any one of the conductor, the first electrode and the second electrode, and the control unit stops generating high-frequency voltage from the high-frequency voltage generating unit to the first electrode and the second electrode based on the result detected by the temperature detection unit.

[0193] According to this configuration, a temperature detection unit is provided for detecting the temperature of at least one of the conductor, the first electrode, and the second electrode. Based on the result detected by the temperature detection unit, the generation of the high-frequency voltage from the high-frequency voltage generator to the first and second electrodes is stopped. Thus, for example, when the temperature of at least one of the conductor, the first electrode, and the second electrode rises excessively, the generation of the high-frequency voltage can be stopped based on the detected temperature. Furthermore, when heat accumulates in at least one of the conductor, the first electrode, and the second electrode, degradation due to the heat can be suppressed, thereby preventing a decrease in printing quality.

[0194] In the liquid ejection device, the high-frequency voltage generator may generate a high-frequency voltage of 10 MHz to 20 GHz, and the distance between the first electrode and the second electrode and the surface of the support portion may be 1 mm to 20 mm.

[0195] According to this structure, the high-frequency voltage generator generates a high-frequency voltage in the range of 10 MHz to 20 GHz, and the distance between the first and second electrodes and the surface of the support portion is 1 mm to 20 mm. Therefore, the distance between the first and second electrodes and the surface of the support portion is set so that a user's fingers, etc., cannot enter between the first and second electrodes and the surface of the support portion. This improves safety even when generating high-frequency voltage.

[0196] Explanation of symbols

[0197] D1 to D3…distance; HP…initial position; PR…program; X…width direction; X1…first width direction; X2…second width direction; Y…conveying direction; Z…vertical direction; 11…printing system; 12…holding device; 13…winding device; 14…liquid ejecting device; 17…holding shaft; 18…winding shaft; 21…supporting portion; 21A…surface; 22…printing portion; 23…control portion; 23A…monitoring portion; 23B…limiting portion; 23C…storage portion; 31…slide; 31A…opposing surface; 31B…protruding portion; 31C…outer edge portion; 31D…top surface; 32…liquid ejecting head; 33…drying portion; 34…air supply mechanism; 34A…first passage; 34B…second passage; 34C…first blower; 34D…second blower; 35…optical sensor; 36…electric field detection Detection sensor; 37…communication unit; 38…slide motor; 39…wiping mechanism; 41…AC electric field generating unit; 42…cover; 43…generator; 44…adjustment mechanism; 45…wiper; 46…moving mechanism; 51…first electrode; 52…second electrode; 53…conductor; 54…axial cable; 54A…inner conductor; 54B…outer conductor; 55…coil; 55A…contact portion; 56…coil supporting portion; 56A…opening; 57…contact member; 57A…contact portion; 58…connecting portion; 58A…opening; 59…connecting member; 60…detection sensor; 61…high-frequency voltage generating unit; 62…monitoring circuit; 63…high-frequency voltage generating circuit; 64…amplifier circuit; 65…rectifier circuit; 66…comparison circuit; 99…medium; 99A…surface; 99B…back surface; 100…reel body.

Claims

1. A liquid ejection device, characterized in that: have: a supporting portion for supporting the medium; a liquid ejecting head that ejects liquid toward the medium supported on the supporting portion; a carriage having an opposing surface on which the liquid ejecting head is mounted; an AC electric field generating unit that generates an AC electric field, The AC electric field generating portion is mounted on a portion of the opposing surface different from a position where the liquid ejecting head is mounted. The AC electric field generating unit includes: a first electrode and a second electrode, which are arranged adjacent to each other; a high-frequency voltage generating unit that generates a high-frequency voltage to the first electrode and the second electrode; and a conductor that electrically connects the first electrode and the second electrode to the high-frequency voltage generating unit. The first electrode is a rectangular flat plate in a plan view along the vertical direction, and the second electrode is a hollow rectangular flat plate surrounding the first electrode in the plan view. The minimum spacing distance between the first electrode and the second electrode is less than one tenth of the wavelength of the AC electric field output from the AC electric field generating unit. The carriage moves back and forth. The first electrode and the second electrode are mounted on the carriage so as to face the support portion. The surface of the support portion facing the liquid ejection head, the first electrode, and the second electrode is made of an insulator. The liquid ejecting device further includes a cover mounted on the carriage and covering the first electrode and the second electrode between the first electrode and the second electrode and the support portion, and a wiper for wiping a surface of the cover.

2. The liquid ejection device according to claim 1, wherein The AC electric field generating unit selectively generates any one of a plurality of AC electric fields having different frequencies.

3. The liquid ejection device according to claim 1 or claim 2, wherein: A changing portion is provided that changes a distance between at least one of the first electrode and the second electrode and the support portion.

4. The liquid ejecting device according to claim 1, wherein A blower is provided for blowing air toward the first electrode and the second electrode. In a direction perpendicular to the surface of the support portion, a distance between the surface of the support portion and the air supply portion is greater than a distance between the surface of the support portion and the first electrode and the second electrode.

5. The liquid ejecting device according to claim 1, wherein The conductor comprises a wound wire, The liquid ejecting device includes an air supply unit configured to supply air to the winding wire.

6. The liquid ejecting device according to claim 1, wherein have: a control unit configured to control the AC electric field generating unit; a temperature detection unit configured to detect a temperature of at least one of the conductor, the first electrode, and the second electrode; The control unit stops the high-frequency voltage generation unit from generating the high-frequency voltage to the first electrode and the second electrode based on the result detected by the temperature detection unit.

7. The liquid ejecting device according to claim 1, wherein The high-frequency voltage generating unit generates a high-frequency voltage of 10 MHz to 20 GHz. The distance between the first electrode and the second electrode and the surface of the support portion is 1 mm to 20 mm.

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