Liquid ejection device

Abstract

The present application provides a liquid ejecting apparatus capable of improving safety against abnormality. An alternating-current electric field generating section has a first electrode and a second electrode which are arranged adjacent to each other, a high-frequency voltage generating section which generates a high-frequency voltage to the first electrode and the second electrode, and a conductor which electrically connects the first electrode and the second electrode to the high-frequency voltage generating section. A control section stops generation of the high-frequency voltage from the high-frequency voltage generating section to the first electrode and the second electrode based on a result detected by a detection section which detects a change in the alternating-current electric field generated from the alternating-current electric field generating section.

Description

Technical Field

[0001] This invention relates to a liquid ejection device having a liquid ejection head that ejects liquids such as ink onto a medium such as paper. Background Technology

[0002] For example, Patent Document 1 discloses a liquid ejection device, such as an inkjet printer, that ejects liquids such as ink onto a medium like paper for printing. This liquid ejection device is equipped with a function that, in order to suppress a decrease in print quality, such as ink bleeding, caused by variations in the degree of dryness of the ejected liquid medium, it generates an alternating electric field by generating a high-frequency voltage to alternately arranged anodes and cathodes, thereby induction heating the liquid ejected onto the medium to dry the medium.

[0003] However, in the liquid ejection device described in Patent Document 1, there may be abnormalities such as changes in the alternating electric field due to changes over time or usage conditions beyond the designer's intention, changes in the conditions for heating the liquid ejected onto the medium, and excessive heat accumulation on each electrode.

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

[0005] A liquid ejection device for solving the above-mentioned problems includes: a liquid ejection head that ejects liquid to a medium; an alternating current (AC) electric field generating unit that generates an AC electric field; a control unit that controls the AC electric field generating unit; and a detection unit that detects changes in the AC electric field generated by the AC electric field generating unit. The AC electric field generating unit has: a first electrode and a second electrode 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 control unit stops generating the 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 detection unit.

[0006] A liquid ejection device for solving the above-mentioned problems includes: a liquid ejection head that ejects liquid to a medium; an alternating current (AC) electric field generating unit that generates an AC electric field; a control unit that controls the AC electric field generating unit; and a temperature detection unit that detects temperature. The AC electric field generating unit has: a first electrode and a second electrode 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 temperature detection unit detects the temperature of at least one of the conductor, the first electrode, and the second electrode. The control unit stops generating the 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 detection unit. Attached Figure Description

[0007] Figure 1 This is a schematic side sectional view showing the printing system in the first embodiment.

[0008] Figure 2 This is a schematic side sectional view showing the liquid ejection device in the first embodiment.

[0009] Figure 3 This is a schematic bottom view showing the carriage in the first embodiment.

[0010] Figure 4 A perspective view of the generator in the first embodiment.

[0011] Figure 5 This is a schematic diagram illustrating the wiping mechanism.

[0012] Figure 6 A block diagram illustrating the electrical structure of a liquid ejection device.

[0013] Figure 7 A block diagram illustrating the electrical structure of a liquid ejection device.

[0014] Figure 8 This is a flowchart illustrating the monitoring process.

[0015] Figure 9 This is a schematic side sectional view showing the liquid ejection device in the third embodiment.

[0016] Figure 10 This is a perspective view of the generator in the fourth embodiment.

[0017] Figure 11 This is a perspective view of the generator in the fifth embodiment.

[0018] Figure 12 A schematic bottom view showing the carriage. Detailed Implementation

[0019] Hereinafter, an embodiment of a printing system equipped with a liquid ejection device will be described with reference to the accompanying drawings.

[0020] First Implementation Method

[0021] 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 ejection device 14.

[0022] The holding device 12 is a device for holding a roll 100 on which the medium 99 is wound. The holding device 12 has a holding shaft 17 for holding the roll 100. The holding shaft 17 is configured to be rotatable, for example. As the holding shaft 17 rotates, the medium 99 is unwound from the roll 100. In the first embodiment, the holding shaft 17 is not operatively rotated, but rather rotates together with the roll 100, for example, by pulling the medium 99 out of the roll 100. The medium 99 is, for example, a sheet of paper, cloth, or other thin material. The holding shaft 17 may also be a non-rotating structure. In this case, the roll 100 rotates relative to the holding shaft 17 by pulling the medium 99 out of the roll 100.

[0023] The winding device 13 is a device for winding up the medium 99 that is unwound from the holding device 12. The winding device 13 has a winding shaft 18 for winding up the medium 99. The winding shaft 18 is configured to be rotatable. The winding shaft 18 winds up the medium 99 by rotating. As a result, the winding shaft 18 holds the roll body 100 formed by winding up the medium 99. In the first embodiment, the medium 99 is unwound from the roll body 100 held on the holding shaft 17 by rotating the winding shaft 18.

[0024] The medium 99 is conveyed by being wound by the winding device 13. The medium 99 is conveyed from the holding device 12 toward the winding device 13. In the first embodiment, the direction from the holding device 12 toward the winding device 13 is the conveying direction Y of the medium 99. The medium 99 has a surface 99A and a back surface 99B, which is the opposite side of the surface 99A.

[0025] The liquid ejection device 14 is a device for printing on the medium 99. For example, the liquid ejection device 14 is an inkjet printer that prints text, photographs, graphics, and other images 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 transport direction Y.

[0026] The liquid dispensing device 14 includes a support 21, a printing section 22, and a control section 23. The control section 23 controls at least the various structures of the liquid dispensing device 14.

[0027] Although the support portion 21 is, for example, a plate-shaped component, it can also be an adhesive tape coated with an adhesive material or an electrostatically adsorbent tape. The support portion 21 supports the medium 99 being transported. 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.

[0028] In the first embodiment, the support portion 21 has a surface 21A that faces the printing portion 22 in the vertical direction Z. In the first embodiment, at least the surface 21A of the support portion 21 is made of an insulator. As a specific example, it is preferable that the surface 21A of the support portion 21 is an insulator with a strength of 0.0001 S / m or less. The surface 21A of the support portion 21 is formed with an alumina coating by performing an alumina film processing, but is not limited thereto; for example, an insulating coating may be formed by applying an insulating material. Furthermore, the support portion 21 itself may be an insulating material. Moreover, as long as the area of ​​the surface 21A of the support portion 21 facing the printing portion 22 is an insulator, whether the other areas are insulators is arbitrary.

[0029] The printing section 22 is positioned opposite the support section 21 in the vertical direction Z. In the first embodiment, the printing section 22 is located above the support section 21. The printing section 22 is configured to print on the medium 99.

[0030] like Figure 1 as well as Figure 2 As shown, in the first embodiment, the printing unit 22 includes a carriage 31, a liquid ejector head 32, a drying unit 33, an air supply mechanism 34, and an optical sensor 35.

[0031] The carriage 31 houses a liquid ejector head 32, a drying unit 33, an air supply mechanism 34, and an optical sensor 35. The carriage 31 is positioned opposite the support unit 21 in the vertical direction Z. In the first embodiment, the carriage 31 is located above the support unit 21. The carriage 31 scans the transported medium 99. That is, the carriage 31 moves back and forth above the support unit 21, spanning the width of the medium 99. 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 ejector head 32 scans the medium 99.

[0032] The width direction X represents both directions, including the first width direction X1 and the second width direction X2. The first width direction X1 is the opposite direction to the second width direction X2. The width direction X is different from the conveying direction Y and the vertical direction Z; it is orthogonal to the conveying direction Y and the vertical direction Z.

[0033] In the first embodiment, the carriage 31 has an opposing surface 31A. The opposing 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 opposing surface 31A at the outer edge portion 31C of the opposing 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 1mm to 20mm, so that the user's fingers or the like cannot enter between the opposing surface 31A of the carriage 31 and the surface 21A of the support portion 21.

[0034] A liquid nozzle 32 is mounted on the opposing surface 31A of the carriage 31. The liquid nozzle 32 is opposite to the support portion 21 in the vertical direction Z. In the first embodiment, the liquid nozzle 32 is located above the support portion 21. Thus, the liquid nozzle 32 is mounted on the carriage 31 facing the support portion 21.

[0035] The liquid ejector head 32 has a nozzle plate with nozzles for ejecting liquid. The liquid ejector head 32 ejects liquid onto a medium 99 supported on a support portion 21. As a result, an image is printed on the medium 99. In a first embodiment, the liquid ejector head 32 ejects liquid onto the surface 99A of the medium 99. The liquid ejected by the liquid ejector head 32 is, for example, a water-based ink with water as a solvent.

[0036] When the liquid nozzle 32 sprays liquid into the medium 99, the water content of the medium 99 increases. That is, the liquid nozzle 32 performs a process to increase the water content of the medium 99 by spraying liquid into the medium 99.

[0037] The drying unit 33 is mounted on the opposing surface 31A of the carriage 31. The drying unit 33 includes an alternating current (AC) electric field generating unit 41 and a cover 42. The AC electric field generating unit 41 is opposite to the support unit 21 in the vertical direction Z. In other words, the AC electric field generating unit 41 is opposite to the medium 99 supported on 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.

[0038] The alternating current electric field generating unit 41 generates an alternating current electric field. In the first embodiment, the alternating current electric field generating unit 41 performs the following treatment on the medium 99: heating the moisture contained in the medium 99 by generating an alternating current electric field, thereby reducing the moisture content of the medium 99. In other words, the alternating current 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.

[0039] Although the AC electric field generating unit 41 heats the liquid by generating an AC electric field of 2.4 GHz in the first embodiment, it is not limited to this. For example, high-frequency induction heating that generates an AC electric field of 3 MHz to 300 MHz and microwave heating that generates an AC electric field of 300 MHz to 30 GHz can also be used, among which generating an AC electric field of 10 MHz to 20 GHz is preferred.

[0040] like Figure 3 As shown, the alternating current electric field generating unit 41 has multiple generators 43 for generating an alternating current electric field. The multiple generators 43 are arranged in multiple rows, surrounding both sides in the width direction X and downstream of the conveying direction of the medium 99 relative to the liquid nozzle 32. The multiple generators 43 are arranged inward of the outer periphery of the carriage 31 in a manner that the generated alternating current electric field will not affect the exterior of the carriage 31.

[0041] 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 for detecting alternating current electric fields. The electric field detection sensor 36 is positioned opposite the support portion 21 in the vertical direction Z. The electric field detection sensor 36 is disposed at the end of the carriage 31. In detail, one of the pair of electric field detection antennas is positioned at a corner of the carriage 31 when viewed from the opposing surface 31A. The other of the pair of electric field detection antennas is positioned at a corner diagonally opposite to the corner of the carriage 31 where the electric field detection antenna is disposed when viewed from the opposing surface 31A. Therefore, although the pair of electric field detection antennas are located on opposite sides of the carriage 31, it is not limited to this. In this way, the electric field detection sensor 36 is configured such that the electric field detection antennas are separated from the generator 43, and detects changes in the alternating current electric field generated from the alternating current electric field generating unit 41. In the first embodiment, the electric field detection sensor 36 is an example of a detection unit.

[0042] like Figure 4As shown, the generator 43 has a first electrode 51, a second electrode 52, and a conductor 53. The first electrode 51 is a rectangular plate when viewed from above. The first electrode 51 faces the support portion 21 and is located above the support portion 21. The second electrode 52 is a hollow rectangular plate that surrounds the first electrode 51 when viewed from above. The second electrode 52 faces the support portion 21 and is located above the support portion 21. Thus, the first electrode 51 and the second electrode 52 are arranged adjacent to each other. Furthermore, the first electrode 51 and the second electrode 52 are mounted on the carriage 31 facing the support portion 21.

[0043] Conductor 53 electrically connects the first electrode 51 and the second electrode 52 to the high-frequency voltage generating unit 61 that generates a high-frequency voltage. Conductor 53 has a coaxial cable 54 and a coil 55. The coaxial cable 54 has 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. As an example of a wound wire, the coil 55 is connected between the first electrode 51 and the inner conductor 54A of the coaxial cable 54, and is preferably positioned as close as possible to the first electrode 51.

[0044] The minimum distance between the first electrode 51 and the second electrode 52 is less than one-tenth of the wavelength of the alternating current field output from the alternating current field generating unit 41. This allows most of the alternating current field generated when a high-frequency voltage is applied to attenuate near the first electrode 51 and the second electrode 52. Consequently, the intensity of electromagnetic waves reaching distant locations from the first electrode 51 and the second electrode 52 can be reduced. In other words, the alternating current field generated by the alternating current field generating unit 41 is very strong near the first electrode 51 and the second electrode 52, but very weak at a distance.

[0045] Such a generator 43 generates an AC electric field in a concentrated range, for example, 3 mm to 3 cm, in the vicinity of the first electrode 51 and the second electrode 52 by appropriately controlling the frequency band of the generated AC electric field, thereby making it less likely to cause the influence of the AC electric field beyond this range.

[0046] like Figure 1 as well as Figure 2As 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 alternating current field generating unit 41. In the first embodiment, the cover 42 covers the alternating current field generating unit 41 from below to prevent foreign matter from adhering to the alternating current field generating unit 41. In particular, even if the liquid sprayed from the liquid nozzle 32 is in the form of a mist, in the first embodiment, the cover 42 covers the alternating current field generating unit 41 from below to prevent liquid from adhering to the alternating current field generating unit 41. Thus, in the first embodiment, the cover 42 is mounted on the carriage 31 such that it covers the generator 43 of the alternating current field generating unit 41 between the alternating current field generating unit 41 and the support unit 21.

[0047] In the first embodiment, the cover 42 is formed of a material that allows the alternating electric field generated from the alternating electric field generating unit 41 to pass through. As a specific example, the cover 42 may also be formed of glass, but is not limited thereto. For example, it may also be formed of a resin with permeability, such as a cyclic olefin copolymer. Preferably, it is a material that is difficult to be affected by induction heating. In the first embodiment, the surface of the cover 42 has an uneven shape, which allows the alternating electric field generated from the alternating electric field generating unit 41 to converge toward the medium 99 supported on the support unit 21.

[0048] In particular, in the first embodiment, the material of the cover 42 is preferably selected from the viewpoints of liquid adhesion, liquid cleanliness, and strength. Regarding its thickness and the transmittance of the alternating electric field, various materials can be used by changing the frequency and configuration of the alternating electric field generating unit 41.

[0049] The drying unit 33 includes an adjustment mechanism 44 that allows the generator 43 of the alternating current field generating unit 41 and the cover 42 to move in the vertical direction Z. As a result, the drying unit 33 can adjust the distance between the alternating current field generating unit 41 and the medium 99. The adjustment mechanism 44 can be, for example, a linkage mechanism or a rack and pinion mechanism. Therefore, the distance between the alternating current field generating unit 41 and the medium 99 can be adjusted according to the type of medium 99, the type of liquid sprayed from the liquid nozzle 32, etc. 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 21. In the first embodiment, the adjustment mechanism 44 is an example of a changing unit.

[0050] like Figure 2 As shown, the air supply mechanism 34 is mounted on the carriage 31. The air supply mechanism 34 has a first channel 34A, a second channel 34B, a first blower 34C, and a second blower 34D.

[0051] The first channel 34A is a channel extending in the vertical direction Z between the outer edge 31C of the generator 43 and the carriage 31, adjacent to the generator 43. The second channel 34B is a channel extending in the vertical direction Z between the liquid nozzle 32 and the generator 43, adjacent to the generator 43. The first channel 34A and the second channel 34B are not only located downstream of the liquid nozzle 32 in the transport direction Y of the medium 99, but also located on both sides in the width direction X of the medium 99.

[0052] A first blower 34C is positioned at the upper end of the first channel 34A. The first blower 34C is a fan that supplies air from the outside of the carriage 31 to the first channel 34A. A second blower 34D is positioned at the upper end of the second channel 34B of the carriage 31. The second blower 34D is a fan that supplies air from the second channel 34B to the outside of the carriage 31.

[0053] Thus, air is supplied from the outside of the carriage 31 to the first channel 34A by the drive of the first blower 34C, and air is supplied from the second channel 34B to the outside of the carriage 31 by the drive of the second blower 34D. Consequently, below the cover 42, the gas flows from the outer edge 31C toward the liquid nozzle 32. In the air supply mechanism 34 located downstream of the liquid nozzle 32 in the transport direction Y, below the cover 42, the gas flows from downstream to upstream in the transport direction Y of the medium 99. In the air supply mechanism 34 located outside the liquid nozzle 32 in the width direction X, below the cover 42, the gas flows from outside to inside in the width direction X. Therefore, even if the liquid sprayed from the liquid nozzle 32 is in a mist form, the adhesion of the mist to the cover 42 can be suppressed.

[0054] Thus, in the first embodiment, the first blower 34C supplies air to the generator 43, represented by the coil 55, the first electrode 51, and the second electrode 52. As a result, the generator 43 is cooled. Conversely, the gas supplied to the first blower 34C is heated by the generator 43. The heated gas is blown onto the medium 99 on the support 21. Consequently, the liquid sprayed onto the medium 99 is heated, thereby promoting the drying of the medium 99.

[0055] In the vertical direction Z, the distance D2 between the surface 21A of the support portion 21 and the first blower 34C and the second blower 34D is greater than the 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 blower 34C and the second blower 34D correspond to an example of an air supply section.

[0056] 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 relative to the carriage 31 on the outer peripheral surface upstream of the conveying direction Y, the outer peripheral surface downstream of the conveying direction Y, the outer peripheral surface in the first width direction X1 of the width direction X, and the outer peripheral surface in the second width direction X2 of the width direction X, it is not limited to this.

[0057] An optical sensor 35 is positioned opposite a support portion 21. The optical sensor 35 is located above the support portion 21. The optical sensor 35 illuminates light downwards. That is, the optical sensor 35 illuminates light towards 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 or similar object is present between the optical sensor 35 and the support portion 21. Therefore, it is possible to detect the presence of a user's finger or similar object between the optical sensor 35 and the support portion 21 based on the results detected by the optical sensor 35.

[0058] like Figure 5 As shown, the liquid dispensing device 14 includes a wiping mechanism 39. The wiping mechanism 39 wipes away liquids and other substances adhering to the liquid nozzle 32 and the cover 42. The wiping mechanism 39 is positioned at the initial position of the carriage 31, facing the opposing surface 31A of the carriage 31. The liquid nozzle 32 and the cover 42 are disposed on the opposing surface 31A of the carriage 31. Therefore, the wiping mechanism 39 is positioned at the initial position of the carriage 31, facing the liquid nozzle 32 and the cover 42. The initial position HP of the carriage 31 is the position of one end of the travel range of the carriage 31, and is the standby position of the carriage 31.

[0059] The wiping mechanism 39 includes a wiper 45 and a moving mechanism 46. The wiper 45 wipes the surface of the liquid nozzle 32 and the surface of the cover 42. The wiper 45 is made of resin such as rubber or elastomer, but is not limited to this; for example, it can also be made of cloth. The moving mechanism 46 causes the wiper 45 to move back and forth. Driven by the moving mechanism 46, the wiper 45 moves back and forth in a manner that wipes the surface of the liquid nozzle 32 and the surface of the cover 42, which are stationary at the initial position HP, and moves relative to the liquid nozzle 32 and the cover 42. As a result, the wiper 45 can remove the liquid adhering to the surface of the liquid nozzle 32 and the surface of the cover 42, and can form a waterproof film on the surface of the cover 42.

[0060] Next, the electrical structure of the liquid ejection device 14 will be explained.

[0061] like Figure 6 As shown, the liquid dispensing 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 an integrated circuit for a specific purpose, that executes at least a portion of the various processes; or γ: a combination thereof. The processor includes a CPU and memories such as RAM and ROM, which store program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes all readable media that can be accessed using a general-purpose or special-purpose computer.

[0062] An optical sensor 35, an electric field detection sensor 36, and a communication unit 37 are electrically connected to the control unit 23. 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.

[0063] 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 or sends signals to the terminal device as needed. In the first embodiment, when printing task or other instruction information is input from the terminal device, the control unit 23 performs processing corresponding to the instruction information and outputs result information, such as the execution result, to the terminal device. The liquid dispensing device 14 may also include an operation unit operable by a user and a display unit displaying various information.

[0064] In the first embodiment, the control unit 23 is configured 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 as needed, or sends signals to the holding device 12 and the winding device 13. In this way, the control unit 23 can perform unified control of the printing system 11.

[0065] 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 supply mechanism 34, and the wiping mechanism 39.

[0066] In the first embodiment, the control unit 23 outputs a signal to the printing unit 22, instructing it to spray liquid and perform printing, based on printed image data. In the first embodiment, the control unit 23 outputs a signal to the carriage motor 38 to cause 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 driving of the AC electric field generating unit 41. In the first embodiment, the control unit 23 receives 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 to drive 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 to drive the wiping mechanism 39.

[0067] The control unit 23 includes a monitoring unit 23A and a limiting unit 23B. The monitoring unit 23A monitors whether a limiting condition for at least restricting the driving of the AC electric field generating unit 41 is met, 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 from the monitoring unit 23A, at least restricts the driving of the AC electric field generating unit 41 when the limiting condition is met. The control unit 23 includes a storage unit 23C, which is a memory such as ROM and RAM. The storage unit 23C stores various data, such as program PR.

[0068] In addition, such as 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.

[0069] The high-frequency voltage generating unit 61 is connected to the generator 43. Specifically, the high-frequency voltage generating unit 61 is connected to the first electrode 51 and the second electrode 52 via the conductor 53. The high-frequency voltage generating unit 61 generates a high-frequency voltage to the first electrode 51 and the second electrode 52, and generates an alternating 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.

[0070] The high-frequency voltage generating unit 61 includes a high-frequency voltage generating circuit 63 and an amplification circuit 64. The high-frequency voltage generating circuit 63 is connected to the control unit 23 and the amplification circuit 64. The high-frequency voltage generating circuit 63 is a circuit that generates a high-frequency voltage based on a generation instruction signal from the control unit 23 and outputs it to the amplification circuit 64. The amplification circuit 64 is a circuit that 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. Although in the first embodiment, the high-frequency voltage generating unit 61 supplies power of 3KW or less to the generator 43, it is not limited to this.

[0071] 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 result of monitoring the high-frequency voltage to the control unit 23.

[0072] The monitoring circuit 62 includes a rectifier circuit 65 and a comparator circuit 66. The rectifier circuit 65 is connected to the high-frequency voltage generator 61 and the comparator circuit 66. The rectifier circuit 65 converts the high-frequency voltage from the high-frequency voltage generator 61 into DC by rectifying and smoothing it, and outputs it to the comparator circuit 66.

[0073] The comparator circuit 66 is connected to the rectifier circuit 65 and the control unit 23. The comparator circuit 66 compares the signal output from the rectifier circuit 65 with the reference voltage. When the signal output from the rectifier circuit 65 exceeds the reference voltage, the comparator circuit 66 outputs a signal indicating that the signal exceeds the reference voltage to the control unit 23.

[0074] In the first embodiment, the monitoring circuit 62 utilizes the characteristic that the resistance (i.e., impedance) of the coil 55 changes due to abnormal heating to monitor the high-frequency voltage input to the generator 43. When the high-frequency voltage exceeds a reference voltage, it infers that the temperature of the coil 55 has risen and detects abnormal heating related to the generator 43. In particular, sometimes the temperature of the generator 43 rises due to the heating of the coil 55. If the temperature change of the coil 55 can be monitored, abnormal heating of the generator 43 can be detected. Specifically, in the first embodiment, the coil 55 is a copper coil. Copper's resistance changes significantly with temperature; if the temperature rises by about 50°C, it can be detected even with a simple circuit.

[0075] Although in the first embodiment, a diode for rectification and a capacitor for smoothing are used in the rectifier circuit 65 in the monitoring circuit 62, and a Zener diode is used in the comparator circuit 66 to generate a reference voltage, the embodiment is not limited to these. Furthermore, even when the frequency of the alternating current field generated by the generator 43 changes due to variations in time, the monitoring circuit 62 can detect any abnormalities related to the generator 43 because the resistance of the generator 43, especially the resistance of the coil 55, changes. 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 is an example of a detection unit and a temperature detection unit.

[0076] In the first embodiment, the control unit 23 stops the start of printing if a limitation condition is met when printing begins. The control unit 23 also stops printing while printing is in progress after printing has begun, if a limitation condition is met. This limitation condition is based on signals from the monitoring circuit 62, as well as signals from the optical sensor 35 and the electric field detection sensor 36.

[0077] The printing process performed by the control unit 23 will be described below. In the first embodiment, the control unit 23 performs the process when a printing task is input via the communication unit 37 after the power to the liquid ejection device 14 is turned on. In the first embodiment, the printing task includes data such as the image to be printed and the resolution of the printed image.

[0078] In the printing process, the control unit 23 sends a signal based on the printed image data to the printing unit 22, causing liquid to be ejected from the liquid ejector head 32. The control unit 23 sends a signal to the AC electric field generating unit 41 and drives the AC electric field generating unit 41, thereby generating an AC electric field from the AC electric field generating unit 41. The control unit 23 sends a signal to the air supply mechanism 34, thereby driving the first blower 34C and the second blower 34D.

[0079] The control unit 23 sends a signal to the carriage motor 38, causing the carriage 31 to move back and forth in the width direction X. The control unit 23 also sends a signal to the take-up device 13 via the communication unit 37, thereby transporting the medium 99 at a speed corresponding to the resolution. As a result, the control unit 23 sprays 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 printing completion conditions, such as the completion of printing image data, are met.

[0080] Next, refer to Figure 8 The monitoring process performed by the control unit 23 will be explained. In the first embodiment, the control unit 23 performs monitoring process at predetermined intervals from the time the printing task is input until the printing end conditions are met after the power to the liquid dispensing device 14 is turned on.

[0081] like Figure 8 As shown, in step S11, the control unit 23 determines whether the restriction condition is met. If the control unit 23 determines that the restriction condition is not met, 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 met, it proceeds to step S12.

[0082] In the first embodiment, the limiting condition is established when it is determined, based on a signal from the optical sensor 35, that a user's finger or the like is present between the optical sensor 35 and the support portion 21. In the first embodiment, the limiting condition is established when the alternating current electric field detected, based on a signal from the electric field detection sensor 36, exceeds a predetermined intensity. In the first embodiment, the limiting condition is established when abnormal heating of the generator 43 is detected based on a signal from the monitoring circuit 62 of the alternating current electric field generating unit 41.

[0083] In step S12, the control unit 23 performs drive restriction processing and ends the monitoring process. During this process, the control unit 23 stores restriction information on printing in the storage unit 23C. In the first embodiment, the restriction information is information that will be eliminated when the restriction conditions are no longer met.

[0084] In detail, when the restriction conditions are met when a printing task is input, the control unit 23 stores the restriction information in the storage unit 23C, and the printing end condition is met, thus ending the printing 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 generation unit 61 of the AC electric field generation unit 41, preventing the high-frequency voltage generation unit 61 from starting to generate high-frequency voltage.

[0085] When the printing restriction conditions are met during printing, the control unit 23 stores the restriction information in the storage unit 23C, and the printing end condition is met, thus ending the printing process and stopping printing. In particular, in the first embodiment, the control unit 23 controls the process by cutting 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 amplification of the high-frequency voltage. In this way, the control unit 23 stops the generation of high-frequency voltage from the high-frequency voltage generator 61 to the first electrode 51 and the second electrode 52 by stopping the power supply to the amplifier circuit 64 based on the results detected by the optical sensor 35, the electric field detection sensor 36, and the monitoring circuit 62. Furthermore, the control unit 23 stops sending signals to the high-frequency voltage generator 61 of the AC electric field generator 41.

[0086] Next, the function of the liquid ejection device 14 will be explained.

[0087] In the liquid ejection device 14, the distance between the generator 43 of the AC electric field generating unit 41 and the cover 42 and the support 21 can be adjusted by adjusting the adjustment mechanism 44. As a result, the distance between the generator 43 of the AC electric field generating unit 41 and the cover 42 and the support 21 can be adjusted to an appropriate distance corresponding to the type of medium 99 and the type of liquid.

[0088] When a printing task is input, liquid is ejected from the liquid nozzle 32 onto the medium 99 supported on the support 21 based on the printing image data. The carriage 31 reciprocates in the width direction X. The medium 99 is conveyed in the transport direction Y. In this way, the image is printed on the conveyed medium 99.

[0089] When an image is printed on the medium 99, a high-frequency voltage is output from the high-frequency voltage generating unit 61 to the generator 43 based on a signal from the control unit 23. The generator 43 generates an alternating electric field when the high-frequency voltage is input, and dries the medium 99 supported on the support unit 21.

[0090] When an image is printed on the medium 99, the first blower 34C and the second blower 34D are driven based on signals from the control unit 23. This causes air to be supplied from the outside of the carriage 31 to the first channel 34A adjacent to the generator 43 of the AC electric field generating unit 41. Furthermore, air is supplied from the second channel 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 onto the medium 99 on the support 21. As a result, the liquid sprayed onto the medium 99 is heated, thereby promoting the drying of the medium 99. Furthermore, below the cover 42, the gas flows from the outer edge 31C toward the liquid nozzle 32. Therefore, it is possible to prevent the liquid sprayed from the liquid nozzle 32 from becoming a mist and adhering to the cover 42.

[0091] The carriage 31 has a protrusion 31B, which prevents the user's fingers or other objects 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 if the user's fingers or other objects have entered between the carriage 31 and the support portion 21. When the user's fingers or other objects are detected entering between the carriage 31 and the support portion 21, control is performed in a manner that at least no alternating current electric field is generated from the alternating current electric field generating unit 41.

[0092] An electric field detection sensor 36 is disposed on the carriage 31 at a position separate from the generator 43. When an alternating current electric field generated by the generator 43 is detected to exceed a predetermined intensity based on a signal from the electric field detection sensor 36, control is performed to at least prevent the generation of an alternating current electric field from the alternating current electric field generating unit 41. 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 alternating current electric field generating unit 41, control is performed to at least prevent the generation of an alternating current electric field from the alternating current electric field generating unit 41.

[0093] As described in detail above, the following effects can be obtained according to this embodiment.

[0094] (1) An alternating electric field is used to dry the liquid ejected onto the medium 99. Compared with the case of using infrared light, for example, when drying areas of the medium 99 where the liquid content is extremely low and no liquid has been ejected, excessive temperature rise in those areas can be suppressed, and degradation of the medium 99 can be prevented. Furthermore, not only for the medium 99, excessive temperature rise can be suppressed in the same way for various peripheral components, and degradation of various peripheral components can be suppressed, without the need for excessive heat insulation materials or heat dissipation components such as reflectors for various peripheral components.

[0095] (2) When using an alternating electric field, compared with the case of using infrared radiation, it is possible to shorten the time from the state where the liquid ejected to the medium 99 is not dried to the state where it is dried, and the time from the state where the liquid ejected to the medium 99 is dried to the state where it is not dried.

[0096] (3) When using an alternating electric field, components for ensuring visual confirmation are not used, compared to the case of using halogen lamps, etc. Furthermore, the use of components such as quartz glass in halogen lamps, etc., reduces thermal efficiency, but the absence of such components in the alternating electric field helps to suppress the reduction in thermal efficiency.

[0097] (4) The alternating current field generating unit 41 is configured to have a first electrode 51 and a second electrode 52 arranged adjacent to each other, a high-frequency voltage generating unit 61 that generates a high-frequency voltage to the first electrode 51 and the second electrode 52, and a conductor 53 that electrically connects the first electrode and the second electrode to the high-frequency voltage generating unit 61. This allows the alternating current field to be concentrated near the first electrode 51 and the second electrode 52, thereby improving the heating efficiency of the liquid ejected onto the medium 99 supported by the support unit 21 and improving the drying efficiency of the medium 99, thus improving print quality. On the other hand, it makes it difficult for the alternating current field to be generated at a position separated from the first electrode 51 and the second electrode 52, thus eliminating the need for excessively configured components for suppressing the alternating current field. This helps to prevent the deterioration of the operating performance of the liquid ejection device 14 and the increase in the size of the liquid ejection device 14, and also improves user safety.

[0098] (5) Furthermore, although induction heating has been used for the liquid sprayed onto the medium 99 in the past, it is desirable to further improve the heating efficiency of the liquid sprayed onto the medium 99 by effectively transmitting the generated alternating electric field to the liquid sprayed onto the medium 99, for example, in order to suppress the degradation of print quality and achieve higher print quality. Therefore, for the surface 21A of the support portion 21 facing the first electrode 51 and the second electrode 52, compared to the case where it is made of a conductor, it is more possible to generate an electric field in a direction that is almost parallel to the surface 21A of the support portion 21 when it is made of an insulator. Therefore, the heating efficiency of the liquid sprayed 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 print quality.

[0099] (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 sprayed onto the medium 99 can be varied according to this distance. Therefore, the liquid can be heated and dried according to the state of the medium 99, for example, by changing the distance according to the thickness or material of the medium 99, the permeability of the liquid, the amount of liquid sprayed onto the medium 99, or the material of the liquid, thereby improving the printing quality.

[0100] To give a specific example, the distance between the generator 43 and the support 21 can be varied depending on the type of medium 99, thereby suppressing the degradation of print quality. Types of medium 99 include, for example, paper, cloth, media woven from a blend of various fibers, and media containing functional raw materials such as silver, allowing for flexible adaptation to various media. Furthermore, drying of the medium 99 can be performed based on the degree of liquid penetration, such as after liquid has penetrated the medium 99. In particular, conventionally, for example, when the medium 99 is thin paper, rapid and excessive drying of the medium 99 can sometimes cause wrinkles to form on the medium 99 due to liquid absorption. Therefore, by varying the distance between the generator 43 and the support 21 in a manner that prevents rapid and excessive drying of the medium 99, wrinkles on the medium 99 can be suppressed. Furthermore, in the past, when a multilayer medium 99 was constructed by combining various metal plates with different coefficients of thermal expansion, wrinkles sometimes occurred on the medium 99 due to the different coefficients of thermal expansion after the liquid had permeated through multiple layers. Therefore, by changing the distance between the generator 43 and the support 21 to dry the medium 99 before the liquid has permeated through multiple layers, wrinkles on the medium 99 can be suppressed.

[0101] (7) By providing a cover 42 that covers the first electrode 51 and the second electrode 52, contact between the first electrode 51 and the second electrode 52 and the medium 99 can be suppressed, and even if the liquid sprayed from the liquid nozzle 32 becomes a mist, the atomized liquid can be prevented from adhering to the first electrode 51 and the second electrode 52. Therefore, the reduction in heating efficiency of the liquid caused by the adhesion of the atomized liquid to the first electrode 51 and the second electrode 52 can be suppressed, thereby suppressing the reduction in drying efficiency of the medium 99, and thus suppressing the reduction in printing quality.

[0102] (8) By providing a wiper 45 for wiping the surface of the cover 42, even if the liquid sprayed from the liquid nozzle 32 is in the form of a mist and adheres to the surface of the cover 42, the liquid adhering to the surface of the cover 42 can be wiped away. Furthermore, 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, the reduction in heating efficiency of the liquid caused by the adhesion of the misted liquid to the cover 42 can be suppressed, thereby suppressing the reduction in drying efficiency of the medium 99, and thus suppressing the reduction in print quality.

[0103] (9) Conventionally, for example, when drying areas of the medium 99 with extremely low liquid content, heat can easily accumulate in the first electrode 51 and the second electrode 52, resulting in excessive heat buildup. Therefore, by supplying air to the first electrode 51 and the second electrode 52, heat can be dissipated even when heat accumulates in them. Thus, the deterioration of the first electrode 51 and the second electrode 52 caused by heat can be suppressed, thereby preventing a decrease in print quality.

[0104] (10) Furthermore, in the vertical direction Z, 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 supplying air from the first electrode 51 and the second electrode 52 toward the support portion 21 in the vertical direction Z, heated gas is blown toward the medium 99 supported on the support portion 21 along with the heat dissipation of the first electrode 51 and the second electrode 52. Therefore, the heating efficiency of the liquid sprayed onto the medium 99 supported by the support portion 21 can be improved, thereby improving the drying efficiency of the medium 99 and thus improving the printing quality.

[0105] (11) Furthermore, even if the liquid ejected from the liquid nozzle 32 becomes a mist, by blowing air from the first electrode 51 and the second electrode 52 toward the support portion 21 in the vertical direction Z, it is possible to suppress the adhesion of the misted liquid to the first electrode 51 and the second electrode 52. Therefore, it is possible to suppress the reduction in heating efficiency of the liquid caused by the adhesion of the misted liquid to the first electrode 51 and the second electrode 52, thereby suppressing the reduction in drying efficiency of the medium 99, and thus suppressing the reduction in printing quality.

[0106] (12) Conventionally, for example, when drying areas with extremely low liquid content in the medium, heat can easily accumulate in the coil 55 contained in the conductor 53, resulting in excessive heat buildup in the coil 55. Therefore, by providing an air supply mechanism 34 that supplies air to the coil 55 contained in the conductor 53, heat can be dissipated from the coil 55 even when heat is accumulated therein. Thus, deterioration of the coil 55 due to heat can be suppressed, thereby suppressing a decrease in print quality.

[0107] (13) A monitoring circuit 62 is provided to detect the temperature of at least one of the conductor 53, the first electrode 51, and the second electrode 52, and to stop generating high-frequency voltage from the high-frequency voltage generating unit 61 to the first electrode 51 and the second electrode 52 based on the result detected by the monitoring circuit 62. Therefore, for example, if the temperature of at least one of the conductor 53, the first electrode 51, and the second electrode 52 rises excessively, the generation of high-frequency voltage can be stopped based on the detected temperature. Thus, when heat accumulates in at least one of the conductor 53, the first electrode 51, and the second electrode 52, degradation caused by heat can be suppressed, thereby suppressing the reduction in print quality.

[0108] (14) The high-frequency voltage generating unit 61 generates a high-frequency voltage of 10MHz to 20GHz, and the distance between the top surface 31D of the protrusion 31B and the surface 21A of the support 21 is 1mm to 20mm. Therefore, the distance between the top surface 31D of the protrusion 31B and the surface 21A of the support 21 is set in a way that prevents the user's fingers or the like from entering between the first electrode 51 and the second electrode 52 and the surface 21A of the support 21. Therefore, safety can be improved even when a high-frequency voltage is generated.

[0109] (15) Furthermore, in the past, for example, due to changes over time or usage conditions beyond the designer's intention, abnormalities may occur, such as changes in the generated alternating current electric field, changes in the conditions for heating the liquid sprayed onto the medium 99, and excessive heat accumulation on the first electrode 51 and the second electrode 52. Therefore, based on the detection of changes in the alternating current electric field generated by the alternating current electric field generating unit 41, the generation of 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 cases of abnormalities such as deformation of the first electrode 51 and the second electrode 52 due to changes over time or usage conditions beyond the designer's intention, or excessive changes in the alternating current electric field generated by the alternating current electric field generating unit 41, the generation of high-frequency voltage can be stopped based on the detected changes in the alternating current electric field, thereby improving safety against the occurrence of abnormalities.

[0110] (16) Based on the detected temperature of any one of the conductor 53, the first electrode 51, and the second electrode 52, the generation of 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 abnormal situations such as when the temperature of any one of the conductor 53, the first electrode 51, and the second electrode 52 rises excessively due to changes over time or usage conditions unintended by the designer, the generation of high-frequency voltage can be stopped based on the detected temperature, thereby improving safety against the occurrence of abnormalities.

[0111] (17) The electric field detection sensor 36 includes an electric field detection antenna for detecting the intensity of the alternating current electric field. The electric field detection antenna is configured to be separate from the first electrode 51 and the second electrode 52. Therefore, changes in the alternating current electric field can be detected not at locations near the first electrode 51 and the second electrode 52, such as the area where the liquid ejected into the medium 99 dries, but at locations separated from the first electrode 51 and the second electrode 52, such as outside the area where the liquid ejected into the medium 99 dries. Therefore, the possibility of detecting changes in the alternating current electric field generated by the alternating current electric field generating unit 41 can be improved.

[0112] (18) When the high-frequency voltage generation unit 61 stops generating high-frequency voltage to the first electrode 51 and the second electrode 52, the power supply to the amplifier circuit 64 can be stopped, thereby protecting the high-frequency voltage generation unit 61.

[0113] (19) By detecting the changes in the impedance of conductor 53, first electrode 51, and second electrode 52, it is possible to detect changes in the AC field generated by AC field generating unit 41 before the AC field changes excessively. Therefore, the possibility of detecting changes in the AC field generated by AC field generating unit 41 can be increased.

[0114] Second Implementation Method

[0115] Next, a second embodiment embodying the present invention will be described.

[0116] In the first embodiment, it is configured to generate an alternating electric field of one frequency band, but in the second embodiment, it is configured to selectively generate an alternating electric field of any one of multiple frequency bands. In the following description, the same symbols are used for structures and control elements that are the same as those in the already described embodiments, and repeated descriptions are omitted or simplified.

[0117] In the second embodiment, the AC electric field generating unit 41 selectively generates any one of a plurality of high-frequency voltages of different frequencies. As a specific example, the AC electric field generating unit 41 selectively generates either an AC electric field of a first frequency band, such as 915 MHz, or an AC electric field of a second frequency band, such as 2.4 GHz.

[0118] In this configuration, the AC electric field generating unit 41 includes a generator for a first system of AC electric fields for generating a first frequency band and a high-frequency voltage generating unit, and a generator for a second system of AC electric fields for generating a second frequency band and a high-frequency voltage generating unit. The generators for the first system and the second system are alternately arranged in an adjacent manner. As a result, deviations in the intensity of the AC electric field per unit area relative to the dielectric 99 can be suppressed.

[0119] When generating an AC electric field in the first frequency band, the control unit 23 controls the high-frequency voltage generating unit 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 the second frequency band, the control unit 23 controls the high-frequency voltage generating unit of the second system, thereby generating an AC electric field in the second frequency band from the generator of the second system.

[0120] As described in detail above, according to this embodiment, except for (1) in the first embodiment...

[0121] In addition to (19), the following effects can also be obtained.

[0122] (20) The alternating current generating unit 41 selectively generates any one of several types of alternating current fields with different frequencies, thereby changing the heating depth in the thickness direction of the liquid sprayed onto the medium 99 according to that frequency. Therefore, by changing the frequency according to the thickness or material of the medium 99, the permeability of the liquid, the amount or material of the liquid sprayed onto the medium 99, etc., the liquid can be heated according to the state of the medium 99 to dry the medium 99, thereby improving the printing quality.

[0123] Third Implementation Method

[0124] Next, a third embodiment that embodies the present invention will be described.

[0125] 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 can be moved to a first position covering the generator 43 and a second position not covering the generator 43.

[0126] like Figure 9 As shown, in the third embodiment, the cover 42 is movably mounted on the carriage 31. The cover 42 is positioned in a second position that does not cover the generator 43. Thus, the cover 42 is configured to be movable to a first position and a second position. Therefore, by moving the cover 42 to the second position, the medium 99 can be dried using the alternating electric field generated from the generator 43. In this case, the cover 42 may also be made of a material that makes it difficult for an alternating electric field to pass through.

[0127] The cover 42 is not limited to being positioned downstream of the medium 99 in the delivery direction Y of the liquid nozzle 32; it can also be positioned at both ends of the medium 99 in the width direction X. For example, when the carriage 31 moves in the width direction X, the cover 42 can be configured to move and open / close in the width direction X by engaging with locking portions in the support portion 21, etc. Furthermore, for example, it can be configured to have a motor that moves the cover 42, and the control unit 23 can drive the motor to move the cover 42, thereby opening and closing the cover 42. In particular, it is also possible to employ a configuration where, when liquid is ejected from the liquid nozzle 32 in both the first width direction X1 and the second width direction X2, the cover 42 positioned in the direction in which the carriage 31 moves is opened, and the cover 42 positioned in the opposite direction to the direction in which the carriage 31 moves is closed. In this case, for example, the support portion 21 has locking portions at both ends of the width direction X. Alternatively, the cover 42 can be configured such that it engages with the locking portion of the support 21 in a manner that is linked to the movement of the carriage 31 in the width direction X, and is opened when the cover 42 is positioned in the direction in which the carriage 31 moves, and closed when the cover 42 is positioned in the opposite direction to the direction in which the carriage 31 moves. Furthermore, the control unit 23 can also control the opening and closing of the cover 42 selectively to correspond to the printing mode, such as the resolution used in the printing task, for printing images.

[0128] Fourth Implementation Method

[0129] Next, a fourth embodiment that embodies the present invention will be described.

[0130] In the fourth embodiment, the coil 55 is configured to expand and cut off the contacts when abnormal heating of the generator 43 occurs, by utilizing the characteristic that the coil 55 deforms due to thermal expansion.

[0131] like Figure 10 As shown, in the fourth embodiment, the generator 43 has 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.

[0132] The coil 55 is arranged through the opening 56A. Thus, the coil 55 is supported on the coil support 56. The coil 55 has a contact portion 55A that contacts the contact portion 57A of the contact member 57.

[0133] Conductor 53 has contact component 57. Contact component 57 has contact portion 57A that contacts contact portion 55A of coil 55. Contact component 57 is connected to inner conductor 54A of coaxial cable 54.

[0134] When no abnormal heating occurs in coil 55, the contact portion 55A of coil 55 contacts the contact portion 57A of contact member 57, thereby electrically connecting coil 55 and contact member 57. When abnormal heating occurs in coil 55, due to thermal expansion, coil 55 lengthens while supported on coil support portion 56. Consequently, the contact portion 55A of coil 55 no longer contacts the contact portion 57A of contact member 57, thus de-electrically disconnecting coil 55 and contact member 57. This allows the generator 43 to operate without generating an alternating electric field when no high-frequency voltage is input.

[0135] 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 clamping circuit. By configuring such a protection circuit, the coil 55 and the contact member 57 are changed from an electrically connected state to an unconnected state, thus protecting the amplifier circuit 64 even when it is in an unloaded state.

[0136] Fifth Implementation Method

[0137] Next, a fifth embodiment that embodies the present invention will be described.

[0138] In the fifth embodiment, the plurality of generators 43 constituting the alternating current generating unit 41 are connected by flexible components such as wires, metal wires, or resin rods, and the tension of the connected components is detected.

[0139] like Figure 11 As shown, in the fifth embodiment, the generator 43 has a connecting portion 58 extending vertically in the Z direction from the second electrode 52. The connecting portion 58 has an opening 58A at its top end. For example, the opening 58A is open in the width direction X.

[0140] A connecting member 59 is fixed in the opening 58A. The connecting member 59 is a member for connecting a 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.

[0141] 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 thus determines that a limiting condition has been met. For example, when fabric is used as the medium 99, sometimes an external force is applied to the generator 43 during printing or dyeing, such as when a thread flies out of the fabric or comes into contact with the generator 43, causing the generator 43 to physically displace. Even in such cases, the physical displacement of the generator 43 is detected, and the limiting condition is met.

[0142] The connecting member 59 may be fixed to each of the plurality of generators 43 arranged in the transport direction Y, or to each of the plurality of generators 43 arranged in the width direction X. Furthermore, the first electrode 51 may also have a connecting portion 58. Thus, the connecting member 59 and the detection sensor 60 are switches fixed to the first electrode 51 or the second electrode 52 and operate according to the displacement of the first electrode 51 or the second electrode 52. Such a connecting member 59 and the detection sensor 60 correspond to an example of a detection unit.

[0143] By configuring it in this way, it is possible to physically detect, for example, the displacement of the first electrode 51 or the second electrode 52, such as deformation due to contact with the medium 99, causing excessive changes in the alternating electric field generated from the alternating electric field generating unit 41. Therefore, the possibility of detecting changes in the alternating electric field generated from the alternating electric field generating unit 41 can be improved.

[0144] Furthermore, the above-described embodiments can also be modified as shown in the following variations. Moreover, it is possible to create further variations by appropriately combining the above-described embodiments and the variations shown below, and it is also possible to create further variations by appropriately combining the variations shown below with each other.

[0145] While the control unit 23 performs monitoring processing at predetermined intervals when printing is performed after the power to the liquid dispensing device 14 is turned on, it is not limited to this. For example, the control unit 23 may perform monitoring processing immediately after the power to the liquid dispensing device 14 is turned on, perform monitoring processing later, or not perform monitoring processing at all. Furthermore, combinations of these methods are also possible.

[0146] • The monitoring circuit 62 can, for example, cut off the power supply voltage supplied to the amplifier circuit 64 by outputting a signal to the amplifier circuit 64 of the high-frequency voltage generating unit 61 without outputting a signal to the control unit 23.

[0147] While the power supply voltage to the amplifier circuit 64 is cut off when an anomaly is detected, this is not the only limitation; for example, the power supply voltage to the high-frequency voltage generating unit 61 itself may also be cut off. Furthermore, the printing process of the liquid ejection device 14 may or may not be stopped.

[0148] 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 penetrates the support surface of the supporting medium 99 and the back side of the support surface. The suction fan draws air from the support surface to the back side through the suction hole. The control unit 23 implements control to drive the suction fan. In this case, for example, the control unit 23 may also control the suction fan in such a way that when abnormal heating of the generator 43 is detected, the suction force of drawing air from the support surface to the back side through the suction hole is increased. As a result, heat dissipation of the generator 43 disposed on the surface 21A of the support portion 21 can be promoted, and the drying efficiency of the medium 99 can be improved.

[0149] Alternatively, the resonant frequency of the generator 43 may change when there is no liquid in the medium 99. Taking advantage of the characteristic that the reflected wave from the generator 43 to the high-frequency voltage generation unit 61 increases, the monitoring circuit 62 has a circulator that detects the reflected wave, thereby detecting whether there is liquid or not in the medium 99.

[0150] Alternatively, a temperature sensor such as a thermistor or thermostat can be configured in the generator 43, and the generator 43 can detect temperature anomalies based on signals from the temperature sensor. In other words, such a temperature sensor is equivalent to 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] Alternatively, an infrared sensor can be positioned near the generator 43, separate from it, and the temperature anomaly of the generator 43 can be detected based on the 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.

[0152] The control unit 23 can also control the flow in such a way that, when it is determined that a medium 99 with sprayed liquid exists in the area opposite to the AC electric field generating unit 41, an AC electric field is generated from the AC electric field generating unit 41; conversely, when it is determined that a medium 99 with sprayed liquid does not exist in the area opposite to the AC electric field generating unit 41, an AC electric field is not generated from the AC electric field generating unit 41. For example, the control unit 23 can also determine the presence of a medium 99 with sprayed liquid in the area opposite to the AC electric field generating unit 41 based on printed image data and by referring to whether liquid has been sprayed into the area opposite to the AC electric field generating unit 41. Furthermore, for example, the control unit 23 can monitor the drive signal output to the printing unit 22 based on printed image data, and determine the presence of a medium 99 with sprayed liquid in the area opposite to the AC electric field generating unit 41 based on the drive signal and by referring to whether liquid has been sprayed into the area opposite to the AC electric field generating unit 41.

[0153] While configured to detect when a user's finger or similar object enters between the optical sensor 35 and the support portion 21 based on the results detected by the optical sensor 35, it is not limited to this. For example, it could also be configured to detect deformation of the medium 99 caused by blockage or other issues between the optical sensor 35 and the support portion 21. The intensity of the light detected by the optical sensor 35 varies depending on whether a user's finger or similar object is present between the optical sensor 35 and the support portion 21, whether the medium 99 is deformed, or otherwise. Therefore, based on the results detected by the optical sensor 35, it is possible to detect when a user's finger or similar object enters between the optical sensor 35 and the support portion 21, and when the medium 99 is deformed.

[0154] While the optical sensor 35 is mounted on the outer peripheral surface of the carriage 31, it is not limited to this. For example, the optical sensor 35 may be mounted on the opposing surface 31A of the carriage 31, or it may not be mounted at all. As a specific example, if thin paper or vinyl plastic is used as the medium 99, the structure may have a protrusion 31B without increasing the thickness of the medium 99. In this case, the optical sensor 35 may not be mounted.

[0155] While the carriage 31 has a protrusion 31B projecting downward from the opposing surface 31A, it is not limited thereto. For example, the carriage 31 may also be a structure without the protrusion 31B. As a specific example, when a carpet or wooden board or the like is used as the medium 99, it is preferable that the medium 99 is thicker and does not have the protrusion 31B, and it is also preferable that it is equipped with an optical sensor 35.

[0156] • In the case of adopting a structure without optical sensor 35 or a structure without protrusion 31B, the distance between the first electrode 51 and the second electrode 52 and the support portion 21 is preferably 1mm to 20mm, which is inaccessible to the user's fingers or the like.

[0157] Although the liquid nozzle 32 is disposed on the same surface as the opposing surface 31A of the carriage 31, it is not limited thereto. For example, it can be disposed either below the opposing surface 31A of the carriage 31 in a way that protrudes from the opposing surface 31A of the carriage 31, or it can be disposed above the opposing surface 31A of the carriage 31.

[0158] Although the cover 42 is disposed on the same surface as the opposing surface 31A of the carriage 31, it is not limited thereto. For example, it can be disposed either below the opposing surface 31A of the carriage 31 in a way that protrudes from the opposing surface 31A of the carriage 31, or it can be disposed above the opposing surface 31A of the carriage 31.

[0159] • At least one of the first blower 34C and the second blower 34D can also blow air in the opposite direction. Although the first blower 34C and the second blower 34D blow air in the vertical direction Z, they are not limited to this; for example, air can also be blown from downstream to upstream in the conveying direction Y of the medium 99. Either the first blower 34C or the second blower 34D may not be configured.

[0160] The first electrode 51 can also be a square-shaped plate when viewed from above. The second electrode 52 can also be a plate that does not surround the first electrode 51 when viewed from above. The second electrode 52 can also be a square-shaped plate. That is to say, the first electrode 51 and the second electrode 52 only need to be arranged adjacent to each other.

[0161] While the generator 43 of the alternating current field generating unit 41 is configured to adjust both the first electrode 51 and the second electrode 52 in the vertical direction Z, it is not limited to this. For example, it can also be configured to adjust the angles of the first electrode 51 and the second electrode 52. When adjusting the angles of the first electrode 51 and the second electrode 52, it can be a structure that moves either one upward or downward without moving either the first electrode 51 or the second electrode 52, or it can be a structure that moves either one upward and either one downward. In particular, it can be adjusted in such a way that by changing the angles of the first electrode 51 and the second electrode 52 to the direction in which the liquid nozzle 32 is disposed, the position of the medium 99 opposite to the first electrode 51 and the second electrode 52 is brought closer to the direction in which the liquid nozzle 32 is disposed, thereby shortening the distance to the medium 99 opposite to the first electrode 51 and the second electrode 52. On the other hand, adjustment can be made by changing the angle of the first electrode 51 and the second electrode 52 to the opposite direction to the direction in which the liquid nozzle 32 is disposed, thereby moving the position of the medium 99 opposite to the first electrode 51 and the second electrode 52 away from the direction in which the liquid nozzle 32 is disposed, and thus increasing the distance to the medium 99 opposite to the first electrode 51 and the second electrode 52. In this way, by configuring the system so that the angle of the first electrode 51 and the second electrode 52 can be adjusted, the position of the medium 99 opposite to the first electrode 51 and the second electrode 52, and the distance to the medium 99 opposite to the first electrode 51 and the second electrode 52, can be adjusted.

[0162] Although the alternating current field generating unit 41 can be adjusted in the vertical direction Z independently of the liquid ejector head 32, it is not limited to this. For example, it can also be adjusted in the vertical direction Z in a manner that can be linked with the liquid ejector head 32.

[0163] The AC electric field generating unit 41 can also selectively generate AC electric fields of multiple frequency bands by changing at least 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 multiple frequency bands.

[0164] Although the AC electric field generating unit 41 includes multiple system generators 43 and a high-frequency voltage generating unit 61, it is not limited to these. For example, it may also include multiple system generators 43 and a single system high-frequency voltage generating unit 61 that outputs high-frequency voltage to the multiple system generators 43. Furthermore, it may also include multiple system generators 43, multiple system amplifier circuits 64, and a single system high-frequency voltage generating circuit 63 that outputs voltage to the multiple system amplifier circuits 64.

[0165] While the high-frequency voltage generating unit 61 is mounted on the carriage 31, it is not limited to this; for example, it may not be mounted on the carriage 31. When the high-frequency voltage generating unit 61 is not mounted on the carriage 31, the carriage 31 can be made lighter. On the other hand, when the high-frequency voltage generating unit 61 is mounted on the carriage 31, the transmission distance of the high-frequency voltage can be shortened, thereby suppressing the attenuation of the high-frequency voltage and reducing power consumption.

[0166] The AC electric field generating unit 41 may also be configured independently of the carriage 31, rather than being mounted on it. In this case, the carriage 31 can be made lighter. Furthermore, for example, when the AC electric field generating unit 41 is not mounted on the carriage 31 and is configured independently of it, it can either move back and forth in the width direction X or remain stationary. By configuring the AC electric field generating unit 41 to move back and forth in the width direction X without being mounted on the carriage 31, the number of generators 43 configured as AC electric field generating units 41 can be reduced.

[0167] ·like Figure 12 As shown, for example, the generator 43 of the alternating current field generating unit 41 only needs to be positioned appropriately relative to the liquid ejector head 32. As a specific example, the generator 43 can also be positioned appropriately relative to the liquid ejector head 32 to allow the liquid ejected onto the medium 99 to be dried in stages.

[0168] The generator 43 of the AC electric field generating unit 41 may also be arranged in a single row relative to the liquid nozzle 32, without spanning multiple rows. For example, the generator 43 of the AC electric field generating unit 41 may be arranged on one side of the liquid nozzle 32 in the width direction X, but not on the other side in the width direction X. For example, the generator 43 of the AC electric field generating unit 41 may not be arranged on both sides of the liquid nozzle 32 in the width direction X. For example, the generator 43 of the AC electric field generating unit 41 may not be arranged downstream of the liquid nozzle 32 in the transport direction of the medium 99.

[0169] The generator 43 of the alternating current field generating unit 41 can also be positioned upstream of the liquid ejector head 32 in the transport direction of the medium 99. Conventionally, the state of the medium 99 before liquid ejection, such as its moisture content, can lead to reduced print quality, for example, liquid seepage. Therefore, by positioning the first electrode 51 and the second electrode 52 upstream of the liquid ejector head 32 in the transport direction of the medium 99, the medium 99 is heated and dried before being transported, allowing liquid to be ejected from the liquid ejector head 32 onto the transported medium. Thus, the medium can be dried before being ejected from the liquid ejector head 32 onto the medium, thereby improving print quality.

[0170] • A pretreatment unit for pretreatment of the printing medium can also be configured upstream of the media 99 in the transport direction of the printing unit 22. As a specific example, a pretreatment unit for coating the media 99 with a treatment liquid can also be configured. This pretreatment unit can be mounted as a liquid ejection device 14 or as part of a printing system 11 other than the liquid ejection device 14.

[0171] Previously, the state of the medium 99 before liquid spraying, such as its moisture content, could lead to conditions that reduced print quality, such as liquid seepage. Therefore, by heating the processing liquid coated on the medium 99 before it is sprayed from the liquid nozzle 32 onto the medium 99 to dry the medium 99, print quality can be improved.

[0172] • The medium 99 is not limited to paper, and can also be a film or sheet made of synthetic resin, cloth, non-woven fabric, laminated sheet, etc. In addition, the medium 99 is not limited to long strip media such as roll paper, and can be single sheet paper, and is not limited to media that wrinkles when printing defects occur, but can be media that curls.

[0173] • The path of the conveying medium 99 is not limited to a horizontally extending path. For example, it can be any path shape, such as a trapezoidal path when viewed from the side, or a path that conveys from one conveying direction back to the other.

[0174] The liquid ejection device 14 may also have at least one of the holding device 12 and the winding device 13.

[0175] • The liquid ejection device 14 can also be configured to further dry the printed medium 99 independently of the drying section 33.

[0176] • The carriage 31 can also be configured in a line layout, spanning the width X of the medium 99. That is, the liquid ejection device 14 can also be a line printer in which liquid ejection heads 32 configured to span the width of the medium 99 eject liquid together.

[0177] Hereinafter, the technical ideas and effects learned based on the above-described embodiments and their modifications will be described together.

[0178] A liquid ejection device includes: a liquid ejection head that ejects liquid to a medium; an alternating current (AC) electric field generating unit that generates an AC electric field; a control unit that controls the AC electric field generating unit; and a detection unit that detects changes in the AC electric field generated by the AC electric field generating unit. The AC electric field generating unit has: a first electrode and a second electrode 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 control unit stops generating the 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 detection unit.

[0179] According to this structure, a detection unit is provided to detect changes in the alternating current field generated by the alternating current field generating unit, and based on the result detected by the detection unit, the generation of high-frequency voltage from the high-frequency voltage generating unit to the first electrode and the second electrode is stopped. Therefore, even in cases of abnormalities such as deformation of the first and second electrodes due to changes over time or usage conditions unintended by the design, or excessive changes in the alternating current field generated by the alternating current field generating unit, the generation of high-frequency voltage can be stopped based on the detected changes in the alternating current field, thereby improving safety against the occurrence of abnormalities.

[0180] In the above-mentioned liquid ejection device, the high-frequency voltage generating unit may also be configured to include: a high-frequency voltage generating circuit that generates a high-frequency voltage; an amplification circuit that amplifies the high-frequency voltage; and a control unit that stops the generation of high-frequency voltage from the high-frequency voltage generating unit to the first electrode and the second electrode by stopping the power supply to the amplification circuit.

[0181] According to this structure, when the generation of high-frequency voltage from the high-frequency voltage generating unit to the first electrode and the second electrode is stopped, the power supply to the amplifier circuit can be stopped, thereby protecting the high-frequency voltage generating unit.

[0182] In the above-mentioned liquid ejection device, the detection unit may also include an antenna for detecting alternating electric fields and be configured separately from the first electrode and the second electrode.

[0183] According to this structure, the detection unit includes an antenna for detecting the alternating current electric field and is configured to be separate from the first and second electrodes. Therefore, changes in the alternating current electric field can be detected not at locations near the first and second electrodes, such as the area where the liquid sprayed onto the medium is not separated, but at locations separated from the first and second electrodes, such as outside the area where the liquid sprayed onto the medium is dried. Thus, the possibility of detecting changes in the alternating current electric field generated by the alternating current electric field generating unit is improved.

[0184] In the above-mentioned liquid ejection device, the detection unit may also include a switch, which is fixed to the first electrode or the second electrode and operates according to the displacement of the first electrode or the second electrode.

[0185] According to this structure, the detection unit includes a switch fixed to a first electrode or a second electrode, which operates based on the displacement of the first electrode or the second electrode. Therefore, it is possible to physically detect, for example, the displacement of the first electrode or the second electrode due to deformation caused by contact with a medium, resulting in excessive changes in the AC electric field generated by the AC electric field generating unit. Thus, the possibility of detecting changes in the AC electric field generated by the AC electric field generating unit can be improved.

[0186] In the above-mentioned liquid ejection device, the detection unit can also detect changes in the impedance of the conductor, the first electrode, and the second electrode.

[0187] According to this structure, the detection unit detects changes in the impedance of the conductor, the first electrode, and the second electrode, thereby enabling the detection of changes in the AC electric field generated by the AC electric field generating unit before excessive changes occur. Therefore, the possibility of detecting changes in the AC electric field generated by the AC electric field generating unit is increased.

[0188] A liquid ejection device includes: a liquid ejection head that ejects liquid to a medium; an alternating current (AC) electric field generating unit that generates an AC electric field; a control unit that controls the AC electric field generating unit; and a temperature detection unit that detects temperature. The AC electric field generating unit includes: a first electrode and a second electrode 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 temperature detection unit detects the temperature of any one of the conductor, the first electrode, and the second electrode. Based on the result detected by the detection unit, the control unit stops generating a high-frequency voltage from the high-frequency voltage generating unit to the first electrode and the second electrode.

[0189] According to this structure, a temperature detection unit is included, which detects the temperature of at least one of the conductor, the first electrode, and the second electrode, and stops generating a high-frequency voltage from the high-frequency voltage generating unit to the first and second electrodes based on the result detected by the temperature detection unit. Therefore, even in the event of an anomaly such as an excessive temperature rise in at least one of the conductor, the first electrode, and the second electrode due to changes over time or usage conditions unintended by the designer, the generation of the high-frequency voltage can be stopped based on the detected temperature, thereby improving safety in the event of anomalies.

[0190] Symbol Explanation

[0191] D1~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…Rewinding device; 14…Liquid ejection device; 17…Holding shaft; 18…Rewinding shaft; 21…Support; 21A…Surface; 22…Printing section; 23…Control section; 23A…Monitoring section; 23B…Restriction section; 23C…Storage section; 31…Carriage; 31A…Opposing surface; 31B…Protrusion; 31C…Outer edge; 31D…Top surface; 32…Liquid ejector head; 33…Drying section; 34…Air supply mechanism; 34A…First channel; 34B…Second channel; 34C…First blower; 34D…Second blower; 35…Optical sensor; 36…Electrical field detector 37…Sensor; 38…Communication unit; 39…Slide motor; 41…Arc electric field generating unit; 42…Cover; 43…Generator; 44…Adjusting mechanism; 45…Wipeer; 46…Moving mechanism; 51…First electrode; 52…Second electrode; 53…Conductor; 54…Axis cable; 54A…Inner conductor; 54B…Outer conductor; 55…Coil; 55A…Contact part; 56…Coil support part; 56A…Opening; 57…Contact component; 57A…Contact part; 58…Connection part; 58A…Opening; 59…Connection component; 60…Detection sensor; 61…High-frequency voltage generating unit; 62…Monitoring circuit; 63…High-frequency voltage generating circuit; 64…Amplification circuit; 65…Rectifier circuit; 66…Comparison circuit; 99…Dielectric; 99A…Surface; 99B…Back side; 100…Roll body.

Claims

1. A liquid ejection device, characterized in that, have: A liquid ejector head that sprays liquid onto a medium; The alternating current electric field generating unit generates an alternating current electric field. The control unit implements the control of the AC electric field generating unit; The detection unit detects changes in the alternating electric field generated by the alternating electric field generating unit. The alternating current electric field generating unit includes: a first electrode and a second electrode 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. Based on the result detected by the detection unit, the control unit stops generating high-frequency voltage from the high-frequency voltage generating unit to the first electrode and the second electrode. The detection unit includes a switch that is fixed to the first electrode or the second electrode and operates according to the displacement of the first electrode or the second electrode.

2. The liquid ejection device as described in claim 1, characterized in that, The high-frequency voltage generating unit has: A high-frequency voltage generating circuit that generates high-frequency voltage; An amplifier circuit amplifies high-frequency voltages. The control unit stops generating high-frequency voltage from the high-frequency voltage generator to the first electrode and the second electrode by stopping the power supply to the amplifier circuit.

3. The liquid ejection device as described in claim 1 or claim 2, characterized in that, The detection unit includes an antenna for detecting alternating electric fields and is configured to be separate from the first electrode and the second electrode.

4. The liquid ejection device as described in claim 1, characterized in that, The detection unit detects changes in the impedance of the conductor, the first electrode, and the second electrode.

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