Drying device and recording device

Abstract

The present invention provides a drying device capable of heating a liquid adhered to a recording medium more uniformly. The drying device of the present invention includes a heater, which is configured at a predetermined interval relative to the recording medium and dries the liquid coated on the recording medium by high frequency. The drying device is characterized in that the heater has a first electrode and a second electrode, the first electrode is connected to a power supply that outputs the high frequency, the second electrode is connected to the power supply that outputs the high frequency and is separated from the first electrode at a predetermined interval, and the distance between the end of the first electrode and the recording medium is longer than the distance between the central portion of the first electrode and the recording medium.

Description

Technical Field

[0001] The present invention relates to a drying device and a recording device. Background Art

[0002] Various types of recording devices have been developed. In addition, not only recording devices but also various studies have been made on the structures provided in the recording devices. For example, a mechanism for drying ink attached to a recording medium in advance has been studied.

[0003] For example, in Patent Document 1, a high-frequency dielectric heating device is disclosed that dries attached ink by dielectric heating by applying an alternating electric field to a medium. In the device disclosed in Patent Document 1, there is a description to the effect that by forming a hole in one of the electrode groups to which high frequency is input and disposing the other electrode in the hole, isotropic heating can be performed, and thus uniform drying can be performed regardless of the printing pattern.

[0004] However, generally, when high frequency is generated, the generated electric field has a non-uniform intensity distribution, and a distribution also occurs in the intensity of dielectric heating. For example, even in the high-frequency dielectric heating device described in Patent Document 1, an inherent non-uniformity occurs in the electric field generated by the two electrodes, and thus uniform heating may not necessarily be sufficiently performed. Therefore, there is a need for a drying device that can more uniformly heat the liquid attached to the recording medium.

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-016742 Summary of the Invention

[0006] One aspect of the drying device according to the present invention is

[0007] a drying device including a heater configured to be spaced apart from a recording medium by a predetermined interval and dry a liquid applied to the recording medium by high frequency, the drying device being characterized in that

[0008] the heater has a first electrode and a second electrode, the first electrode is connected to a power supply that outputs the high frequency, the second electrode is connected to the power supply that outputs the high frequency and is separated from the first electrode by a predetermined interval,

[0009] a distance between an end portion of the first electrode and the recording medium is longer than a distance between a central portion of the first electrode and the recording medium.

[0010] One aspect of the recording device according to the present invention is

[0011] including a plurality of the above-described drying devices

[0012] A plurality of the drying devices are arranged separately from the recording medium at the predetermined intervals. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 FIG. is a perspective view schematically showing a heater according to a first embodiment.

[0014] Figure 2 FIG. is a perspective view schematically showing a first electrode of a heater according to a first embodiment.

[0015] Figure 3 FIG. is a schematic view of a cross section obtained by cutting a first electrode of a heater according to a first embodiment along a Y-Z plane.

[0016] Figure 4 FIG. is a schematic view of a part of a cross section obtained by cutting a first electrode of a heater according to a first embodiment along an X-Z plane.

[0017] Figure 5 FIG. is a perspective view schematically showing a heater according to a second embodiment.

[0018] Figure 6 FIG. is a schematic view of a cross section obtained by cutting a first electrode of a heater according to a second embodiment along a Y-Z plane.

[0019] Figure 7 FIG. is a perspective view schematically showing a heater according to a third embodiment.

[0020] Figure 8 FIG. is a top view when observing a heater according to a third embodiment in a direction along the Z axis.

[0021] Figure 9 FIG. is a simulation result of a heating amount distribution of a heater according to a first embodiment.

[0022] Figure 10 FIG. is a perspective view schematically showing a heater according to a comparative example.

[0023] Figure 11 FIG. is a simulation result of a heating amount distribution of a heater according to a comparative example.

[0024] Figure 12A FIG. is a simulation result of an electric field distribution of a heater according to a first embodiment.

[0025] Figure 12B FIG. is a simulation result of an electric field distribution of a heater according to a comparative example.

[0026] Figure 13AThe simulation result of the power consumption distribution of the heater according to the second embodiment.

[0027] Figure 13B The simulation result of the power consumption distribution of the heater according to the comparative example.

[0028] Figure 14 The simulation result of the heating amount distribution of the heater according to the third embodiment.

[0029] Figure 15 The schematic diagram of the main part of an example of the recording device according to the embodiment.

[0030] Figure 16 The perspective view schematically showing the drying area of the recording device according to the embodiment and its periphery.

[0031] Figure 17 The perspective view schematically showing the drying area of the recording device according to the embodiment and its periphery. Detailed Embodiment

[0032] Hereinafter, embodiments of the present invention will be described. The embodiments described below are ways of describing examples of the present invention. The present invention is in no way limited by the embodiments below, and also includes various modification methods implemented within the scope of not changing the gist of the present invention. In addition, not all of the structures described below are necessarily the essential structures of the present invention.

[0033] 1. Drying Device

[0034] The drying device according to the present embodiment is a drying device including a heater configured to be spaced apart from a recording medium by a predetermined interval and drying a liquid coated on the recording medium by high frequency. Moreover, the heater has a first electrode connected to a power source that outputs high frequency, and a second electrode connected to the power source that outputs high frequency and separated from the first electrode by a predetermined interval, and the distance between the end of the first electrode and the recording medium is longer than the distance between the central part of the first electrode and the recording medium. Hereinafter, each component will be described in turn with reference to the drawings.

[0035] The drying device of the present embodiment includes a heater. In addition, the drying device of the present embodiment includes a high-frequency power supply (not shown). The high-frequency power supply includes a high-frequency voltage generation circuit. The high-frequency power supply generates a high-frequency voltage applied to the heater. The high-frequency power supply is composed of, for example, a crystal oscillator, a PLL (Phase Locked Loop) circuit, and a power amplifier. The high-frequency voltage generated by the high-frequency power supply is supplied to the heater via, for example, a resonance circuit and a coaxial cable. The basic peripheral circuit structure of the high-frequency power supply of the drying device of the present embodiment is a structure in which the high-frequency signal generated by the PLL circuit is amplified by the power amplifier and supplied to the heater.

[0036] 1.1. Heater (First Embodiment)

[0037] Figure 1 FIG. is a schematic diagram of the heater 100 of the drying device of the first embodiment. The drying device according to the first embodiment includes a heater 100. The heater 100 includes a first electrode 10, a second electrode 20, and a coil 30. One end of the coil 30 is electrically connected to the first electrode 10, and the other end is electrically connected to the high-frequency power supply. In the illustrated example, the other end of the coil 30 is electrically connected to the high-frequency power supply through the inner conductor 50 of the coaxial cable. The second electrode 20 is electrically connected to the high-frequency power supply through, for example, the outer conductor (not shown) of the coaxial cable.

[0038] 1.1.1. First Electrode and Second Electrode

[0039] The first electrode 10 and the second electrode 20 are conductors. The first electrode 10 and the second electrode 20 are composed of capacitors. One of the potentials applied to the first electrode 10 or the second electrode 20 may be the reference potential. In this case, the other of the potentials applied to the first electrode 10 or the second electrode 20 is the high-frequency voltage. In this specification, the electrode to which the reference potential is applied is sometimes referred to as the "reference potential electrode", and the electrode to which the high-frequency voltage is applied is sometimes referred to as the "high-frequency electrode". The reference potential means a fixed potential that serves as a reference for the high-frequency voltage, and may be, for example, the ground potential.

[0040] If the frequency of the high-frequency voltage is above 1 MHz, the effect of heating the object to be heated can be obtained. However, for the frequency of the high-frequency voltage, in the case where the object to be heated is water, since the dielectric loss tangent becomes maximum around 20 GHz, the heating efficiency caused by the dielectric loss tangent also becomes maximum. On the other hand, from the viewpoint of heating the ink, even if the frequency is as low as, for example, 40.68 MHz which is one of the ISM bands, good heating efficiency can be obtained. This is because, although the dielectric loss tangent of water in the ink becomes very low at 40.68 MHz, a large amount of heat generation can be obtained according to the resistive loss caused by the eddy current flowing in the resistance of the liquid on the recording medium.

[0041] In addition, the higher the high-frequency voltage, the greater the amount of heat supplied to the liquid. However, since the high-frequency voltage is transmitted to the heater 100 through a transmission line of usually 50 Ω, in the input of the high-frequency voltage to the heater 100, the voltage is expressed by "high-frequency power = V^2 / R = V^2 / 50".

[0042] Furthermore, in order to suppress the heat generated by the parasitic resistance of the heater 100 and suppress the generation of corona discharge, preferably, the drying device includes a plurality of heaters 100 with a power of about several hundred W. Thereby, the drying device can obtain the effect of suppressing the heat generated by the parasitic resistance of the heater 100 while ensuring the power required for drying the liquid, and obtain the effect of suppressing the generation of corona discharge. In addition, the liquid is heated by the electric field generated between the first electrode 10 and the second electrode 20. The electric field generated between the first electrode 10 and the second electrode 20 becomes a very large value of about 1×10^6 V / m.

[0043] When using the heater 100, a recording medium such as paper, film, or cloth is arranged so as to face the first electrode 10 and the second electrode 20. If used Figure 1 for illustration, the recording medium is arranged substantially parallel so as not to contact the first electrode 10 and the second electrode 20 in the direction below, that is, in the negative direction of the Z-axis direction, compared with the first electrode 10 and the second electrode 20.

[0044] The distance between the end of the first electrode 10 and the recording medium is longer than the distance between the central portion of the first electrode 10 and the recording medium.

[0045] Here, in this specification, the meaning of the statement "viewed from above" means "a top view observed in the direction from the positive direction of the Z-axis to the negative direction".

[0046] The central portion of the first electrode 10 refers to a portion within a specific range that extends from the center of gravity of the first electrode 10 toward the end (outline) of the first electrode 10 in a top view. Additionally, in a top view, the outline of the central portion of the first electrode 10 is a similar shape to the outline of the first electrode 10. And it is assumed that in a top view, the intersection point of the line segment connecting the center of gravity and the outline of the first electrode 10 and the outline of the central portion of the first electrode 10 is located at a position that is 10% of the length of the line segment from the center of gravity.

[0047] Furthermore, the distance between the end portion of the first electrode 10 and the recording medium refers to the distance in the Z-axis direction between the lower surface of the end portion of the first electrode 10 and the surface of the recording medium when the recording medium is arranged relative to the heater 100. Similarly, the distance between the central portion of the first electrode 10 and the recording medium refers to the distance in the Z-axis direction between the lower surface of the central portion of the first electrode 10 and the surface of the recording medium when the recording medium is arranged relative to the heater 100.

[0048] If the first electrode 10 has a shape where the distance between the end portion of the first electrode 10 and the recording medium is longer than the distance between the central portion of the first electrode 10 and the recording medium, it can also be a substantially flat plate shape. On the other hand, the second electrode 20 has a flat plate shape.

[0049] If the first electrode 10 has a shape where the distance between the end portion of the first electrode 10 and the recording medium is longer than the distance between the central portion of the first electrode 10 and the recording medium, the shapes of the first electrode 10 and the second electrode 20 in a top view are arbitrary. For example, they can be a square, a rectangle, a circle, or a shape obtained by combining these shapes. In the illustrated example, in a top view, the second electrode 20 is arranged to surround the first electrode 10. By surrounding the first electrode 10 with the second electrode 20 in this way, the radiation of the far electromagnetic field can be suppressed. Thus, it is possible to keep the level of the electromagnetic field to which the operators around the drying device are exposed at a sufficiently safe level without the condition of electromagnetic shielding.

[0050] In a top view, the shape of the first electrode 10 of the heater 100 is an elongated oval shape. The shape of the second electrode 20 of the heater 100 is a hollow oval shape. In a top view, the second electrode 20 is arranged to surround the first electrode 10. Additionally, preferably, the shape of the first electrode 10 is set to a shape with fewer sharp corners. The reason is to suppress the situation where the electric field concentrates at the corners of the first electrode 10, thereby inducing corona discharge. Since the distance between the end portion of the first electrode 10 of the heater 100 and the recording medium is longer than the distance between the central portion of the first electrode 10 and the recording medium, the situation of inducing corona discharge is suppressed.

[0051] Further, although not shown, the first electrode 10 and the second electrode 20 may each be of any shape in a plan view and be arranged adjacent to each other. In this case, the size of the first electrode 10 and the second electrode 20 in the plan view is, in one of the electrodes, 0.01 cm 2 or more and 100.0 cm 2 or less, preferably 0.1 cm 2 or more and 10.0 cm 2 or less, more preferably 0.5 cm 2 or more and 2.0 cm 2 or less, further preferably 0.5 cm 2 or more and 1.0 cm 2 or less. The area described above is for the case where a frequency of 2.45 GHz is used. If the used frequency is lowered, the area of the electrode will increase. In addition, the areas of the first electrode 10 and the second electrode 20 in the plan view may be the same or different.

[0052] In the heater 100, a high-frequency voltage and a reference potential are supplied to the first electrode 10 having an elliptical shape arranged at the center in a plan view and the second electrode 20 having a hollow elliptical shape surrounding the first electrode 10, respectively. The coil 30 is inserted between the first electrode 10 and the inner conductor 50 of the coaxial cable. Preferably, the distance between the coil 30 and the first electrode 10 is as close as possible.

[0053] Preferably, the first electrode 10 and the second electrode 20 are arranged in a non-overlapping manner in a plan view. In addition, in the illustrated example, the bottom surface of the central portion of the first electrode 10 and the bottom surface (the surface facing the recording medium) of the second electrode 20 are arranged on the same plane. By adopting such an arrangement, it is possible to efficiently radiate predetermined electromagnetic waves to the recording medium.

[0054] The first electrode 10 and the second electrode 20 are mainly composed of materials such as metals, alloys, and conductive oxides. The first electrode 10 and the second electrode 20 may be of the same material as each other or of different materials. The first electrode 10 and the second electrode 20 may be appropriately configured by selecting the thickness or strength in a self-supporting manner, or may be formed on the surface of a substrate or the like made of a material having a low dielectric loss tangent and transmitting electromagnetic waves (not shown) when it is difficult to maintain their strength. In addition, in Figure 1 the example, the second electrode 20 is supported by the support member 40.

[0055] The intensity of the electromagnetic waves radiated from the heater 100 is very strong near the first electrode 10 and the second electrode 20, and becomes very weak in the distance. In this specification, the electromagnetic field generated near the first electrode 10 and the second electrode 20 by the heater 100 is sometimes referred to as the "near electromagnetic field". In addition, in this specification, the electromagnetic field generated by a general heater (antenna) for the purpose of transmitting electromagnetic waves to a distance is sometimes referred to as the "far electromagnetic field". Additionally, the boundary between the near and the far is the position about 1 / 6 of the wavelength of the generated electromagnetic waves away from the heater 100.

[0056] The heater 100 does not radiate electromagnetic waves at intervals of m units, and the electric field density of the electromagnetic waves decays to 30% or less of the electric field density between the first electrode 10 and the second electrode 20 during the period of transmitting a distance of 1 / 6 of its wavelength. Therefore, in a region farther from the device than the distance of about the wavelength of the generated electromagnetic waves, unnecessary radiation is not likely to be generated.

[0057] In the case where the drying device is provided with a plurality of heaters 100, for example, it is okay to use one power amplifier for one heater 100. The output of the PLL circuit can also be divided and supplied to a plurality of power amplifiers to generate electromagnetic waves for each heater 100. In addition, in the case where the drying device is provided with a group of a plurality of heaters 100 and power amplifiers, it is possible to more easily control the high-frequency output of each heater 100 individually.

[0058] 1.1.2. Coil

[0059] The heater 100 is provided with a coil 30, and the coil 30 is connected in series with the first electrode 10 via a wire 55. The first electrode 10 is connected to the path to which a high-frequency voltage is applied via the coil 30. One end of the coil 30 is electrically connected to the first electrode 10, and the other end is connected in series with the high-frequency power supply. For the coil 30, even with the same inductance, the heating energy efficiency of the liquid varies greatly depending on its series insertion position, and it is preferably set as close to the first electrode 10 as possible. Here, the series insertion position refers to the position where the coil 30 between the wire 55 and the first electrode 10 is inserted by series connection. That is, since a high voltage is generated at one end of the coil 30, a strong electric field may be generated between the coil 30 and the first electrode 10, or between the wire 55 connecting the coil 30 and the first electrode 10 and the second electrode 20. Since such an electric field does not contribute to heating, the closer the coil 30 and the first electrode 10 are, the better.

[0060] The heater 100 has a coil 30, which changes the impedance of the resonant circuit. Thus, the following effects can be expected: the effect of matching the impedance of the resonant circuit with the impedance of the heater 100, the effect of increasing the intensity of the electric field generated between the electrodes, and the effect of strengthening the electric field generated between the electrodes by adding the electric field generated by the coil 30.

[0061] 1.1.3. Curvature Radius of the End of the First Electrode

[0062] As Figure 1 In the case of the heater 100 of the first embodiment as shown, the first electrode 10 has a long side direction (X direction in the figure) and a short side direction (Y direction in the figure) in a top view. Thus, when the first electrode 10 has a long side direction and a short side direction, preferably, the curvature radius of the end of the first electrode 10 in the long side direction is larger than the curvature radius of the end of the first electrode 10 in the short side direction.

[0063] Figure 2 FIG. is a schematic view of the first electrode 10 enlarged. Figure 3 is Figure 2 FIG. is a schematic view of a cross-section of the first electrode 10 cut along the Y-Z plane as shown. Figure 4 is Figure 2 FIG. is a schematic view of a part of a cross-section of the first electrode 10 cut along the X-Z plane as shown.

[0064] As Figure 3 and Figure 4 As shown, the curvature radius r of the end of the first electrode 10 in the short side direction is smaller than the curvature radius R of the end of the first electrode 10 in the long side direction. By adopting this method, the end of the first electrode 10 in the long side direction, where the intensity of the electromagnetic field is more likely to concentrate when a high frequency is applied, moves away from the second electrode 20 more gently. Therefore, the effect of alleviating the concentration of the electromagnetic field intensity becomes significant. As a result, it becomes more difficult to generate uneven heating on the recording medium facing the first electrode 10 and the second electrode 20.

[0065] 1.2. Heater (Second Embodiment)

[0066] Figure 5 FIG. is a schematic view of the heater 110 according to the second embodiment. In the heater 110, the coil is not depicted. Figure 6FIG. is a schematic cross-sectional view of the first electrode 10a of the heater 110 taken along the Z-X plane. The heater 110 of the second embodiment also still has the first electrode 10a and the second electrode 20a. Except that the shapes of the first electrode 10a, the second electrode 20a, and the support member 40a of the heater 110 are different from the shapes of the first electrode 10, the second electrode 20, and the support member 40 of the heater 100 of the first embodiment, the rest have the same functions as the heater 100 of the first embodiment. In addition, the first electrode 10a is electrically connected to the high-frequency power supply via the inner conductor 50 of the coaxial cable. The second electrode 20a is also electrically connected to the high-frequency power supply via the support member 40a.

[0067] As Figure 6 shown, even in the heater 110, the first electrode 10a has a shape such that its end is far from the recording medium. That is, the distance between the end of the first electrode 10a and the recording medium is longer than the distance between the central portion of the first electrode 10a and the recording medium. In the heater 110, in the first electrode 10a, the end has a shape that is far from the recording medium, and the central portion has a flat shape. In addition, the second electrode 20a has a flat shape.

[0068] In addition, in the heater 110, the shapes of the first electrode 10a and the second electrode 20a in a top view are circular. In addition, in the illustrated example, in a top view, the circular first electrode 10a is surrounded by the annular second electrode 20a. Even in the heater 110, by surrounding the first electrode 10a with the second electrode 20a, the radiation of the far electromagnetic field can be suppressed to a small level. In addition, as the dimensions of the electrodes of the heater 110, preferably, the diameter of the first electrode 10a is 1 cm or more and 10 cm or less, the outer diameter of the second electrode 20a is 1 cm or more and 20 cm or less, and the gap between the two is 1 cm or more and 5 cm or less.

[0069] 1.3. Heater (Third Embodiment)

[0070] Figure 7 FIG. is a schematic view of the heater 120 according to the third embodiment. Figure 8 FIG. is a schematic view of the heater 120 of the third embodiment in a top view. The heater 120 of the third embodiment has a floating electrode 60. For the heater 120, since it is the same as the heater 100 of the above-described embodiment except for having the floating electrode 60, the same reference numerals will be given to the same components as those of the heater 100 and the description thereof will be omitted. In addition, in this specification, the floating electrode 60 is also referred to as the third electrode.

[0071] Figure 7Shows an example of the floating electrode 60. The floating electrode 60 is disposed between the oval first electrode 10 and the elliptical ring-shaped second electrode 20. The floating electrode 60 is not electrically connected to the first electrode 10 and the second electrode 20, and is supported by an insulator (not shown). The shape of the floating electrode 60 is an elliptical ring shape.

[0072] The floating electrode 60 is not electrically connected to a high-frequency power source, the ground, a reference signal source, etc., and has an independent potential. By disposing the floating electrode 60 as a conductor between the first electrode 10 and the second electrode 20, the intensity of the electromagnetic field generated between the first electrode 10 and the second electrode 20 is averaged on the X-Y plane. The reason is that the electric field between the electrodes is converted into eddy currents by the floating electrode 60. Thereby, the non-uniformity of the intensity of the electromagnetic field generated between the first electrode 10 and the second electrode 20 can be further reduced.

[0073] 1.4. Simulation

[0074] Figure 9 Is the simulation result of the heating amount distribution of the heater 100 according to the above first embodiment. Figure 10 Is a schematic diagram of the heater 130 according to a comparative example having a shape in which the distance between the end portion of the first electrode 10b and the recording medium is longer than the distance between the central portion of the first electrode 10b and the recording medium. Figure 11 Is the simulation result of the heating amount distribution of the heater 130 of the comparative example.

[0075] Figure 10 The heater 130 according to the comparative example shown has a first electrode 10b and a second electrode 20. The heater 130 has the same functions as the heater 100 of the first embodiment except that the shape of the first electrode 10b is different from that of the first electrode 10 of the first embodiment. In addition, the first electrode 10b is electrically connected to the high-frequency power source via the inner conductor 50 of the coaxial cable. The second electrode 20 is also electrically connected to the high-frequency power source.

[0076] As Figure 10 As shown, in the heater 130 of the comparative example, it does not have a shape in which the distance between the end portion of the first electrode 10b and the recording medium is longer than the distance between the central portion of the first electrode 10b and the recording medium. That is, the distance between the end portion of the first electrode 10b and the recording medium is the same as the distance between the central portion of the first electrode 10b and the recording medium.

[0077] Figure 11 Is the simulation result of the heating amount distribution of the heater 130 of the comparative example in a top view. As Figure 11As shown, the elliptical annular region between the first electrode 10b and the second electrode 20 on the recording medium is heated by the heater 130. However, a region where the heating amount is concentrated can be observed near the contour of the first electrode 10b. In this case, it is known that non-uniformity is likely to occur in the heating of the liquid on the recording medium. In addition, there are also heating regions within the contours of the first electrode 10b and the second electrode 20.

[0078] In contrast, if the simulation result of the heating amount distribution of the heater 100 of the first embodiment in a top view is observed ( Figure 9 ), it can be known that the elliptical annular region between the first electrode 10 and the second electrode 20 on the recording medium is heated by the heater 100. However, it can be known that the concentration of the heating amount near the contour of the first electrode 10 is suppressed compared with the heater 130 of the comparative example, and the heating amount is averaged. Thus, it can be known that in the case of having a shape in which the distance between the end portion of the first electrode 10 and the recording medium is longer than the distance between the central portion of the first electrode 10 and the recording medium, non-uniformity is not likely to occur in the heating of the liquid on the recording medium. In addition, in Figure 9 , a heating region can be significantly observed within the contour of the first electrode 10, and more heating regions can also be observed within the contour of the second electrode 20 compared with the heater 130 of the comparative example. This can be considered to be caused by the fact that the distance between the end portion of the first electrode 10 of the heater 100 of the first embodiment and the recording medium is longer than the distance between the central portion of the first electrode 10 and the recording medium.

[0079] Figure 12A is the simulation result of the electric field distribution of the first electrode 10 of the heater 100 of the first embodiment. Figure 12B is the simulation result of the electric field distribution of the first electrode 10b of the heater 130 of the comparative example. Figure 12A and Figure 12B represent the case of observing from the side (Y direction), and the vicinity of the end portion of the electrode is shown in an enlarged manner. If Figure 12A is observed, it can be known that in the heater 100 of the first embodiment, the electric field spreads around the end portion of the first electrode 10 and the concentration is alleviated. In contrast, in the heater 130 of the comparative example, the electric field is concentrated at the end portion of the first electrode 10b.

[0080] Figure 13A is the simulation result of the power consumption distribution of the first electrode 10a of the heater 110 of the second embodiment. Figure 13B is the simulation result of the power consumption distribution of the comparative example when the first electrode 10a of the heater 110 of the second embodiment is flat. For Figure 13BFor the heater of the comparative example simulated herein, although the distance between the end of the first electrode 10a and the recording medium is the same as the distance between the central portion of the first electrode 10a and the recording medium, it is not shown in the drawings. Figure 13A and Figure 13B are shown in a top view. It can be seen that Figure 13A and Figure 13B power is consumed and heat is generated in the annular region between the first electrode and the second electrode. And if we observe Figure 13A , it can be seen that the power consumption distribution extends until the inside of the contour of the first electrode 10 and the spatial concentration of the power consumption is alleviated. In contrast, if we observe Figure 13B , it can be seen that the power consumption is concentrated at the end of the first electrode.

[0081] Figure 14 is the simulation result of the heating amount distribution of the heater 120 of the above-described third embodiment. As shown in Figure 14 , it can be considered that although the long annular region between the first electrode 10 and the second electrode 20 on the recording medium is heated by the heater 120, the heating amount in the region corresponding to the floating electrode 60 is suppressed, and as a result, the concentration of the heating amount is further alleviated.

[0082] 1.5. Effects

[0083] According to the drying device of the present embodiment, when high frequency is applied, it is possible to suppress the uneven heating of the liquid disposed on the recording medium. That is, by making the distance between the end of the first electrode of the heater included in the drying device longer than the distance between the central portion of the first electrode and the recording medium, it is possible to alleviate the strong electromagnetic field generated near the end of at least one of the electrodes and disperse the electromagnetic field toward a position away from both electrodes.

[0084] 2. Recording Device

[0085] The recording device according to the present embodiment includes a plurality of the drying devices of the above-described embodiments. And the plurality of drying devices are separated from the recording medium and arranged at a predetermined interval. Hereinafter, as an example of the recording device, an inkjet recording device 1000 will be described with reference to the drawings.

[0086] Figure 15FIG. 0 is a schematic cross-sectional view showing an outline of the main part of an inkjet recording apparatus 1000 according to an embodiment. The inkjet recording apparatus 1000 includes an inkjet head 200 that applies an ink composition to a recording medium M, heaters 100 of a plurality of drying devices, a moving mechanism 300 that moves the heaters 100 along the recording medium M, conveying rollers T, and guide rollers G.

[0087] In addition, although not shown, the inkjet recording apparatus 1000 includes a carriage that reciprocates the inkjet head 200 in a direction crossing the conveying direction SS of the recording medium M and a control unit that controls the entire apparatus.

[0088] The inkjet head 200 has a structure that performs recording by ejecting a predetermined ink composition from nozzles and attaching it to the recording medium M. In the present embodiment, the inkjet head 200 is a serial inkjet head, and performs multiple scans relative to the recording medium M in the main scanning direction ( Figure 15 in the depth direction) to apply the ink composition to the recording medium M. The inkjet head 200 performs multiple scans relative to the recording medium M in the main scanning direction by moving the carriage in the medium width direction of the recording medium M. The medium width direction refers to the main scanning direction of the inkjet head 200. Scanning in the main scanning direction is also referred to as main scanning.

[0089] In addition, here, the main scanning direction is the direction in which the carriage on which the inkjet head 200 is mounted moves. In Figure 15 it is a direction crossing the sub-scanning direction that is the conveying direction of the recording medium M. During multiple repetitions of the main scanning of the inkjet head 200 and the sub-scanning that is the conveyance of the recording medium M, ink is ejected from the inkjet head 200 at a predetermined timing to attach the ink to a predetermined position on the recording medium M, thereby performing recording relative to the recording medium M.

[0090] In the inkjet head 200, a predetermined ink composition and the like are appropriately supplied through an ink cartridge or the like.

[0091] The method of ejecting ink droplets is not limited to the ejection method of the inkjet head 200, and existing well-known methods can be used. In the present embodiment, a method of ejecting droplets by using the vibration of a piezoelectric element, that is, an ejection method of forming ink droplets by mechanical deformation of an electro-distortion element, is used.

[0092] The inkjet recording apparatus 1000 has a recording area P where the ink composition is attached to the recording medium M by the inkjet head 200 and a drying area D where the recording medium M passing through the recording area P is dried.

[0093] In the drying area D, a plurality of heaters 100 are arranged to face the recording medium M. Each heater 100 is mounted on a moving mechanism 300. The moving mechanism 300 can move the heater 100 in any direction while maintaining the distance between the heater 100 and the recording medium M unchanged. The heater 100 can be arranged on the ink-attached surface side of the recording medium M or on the side opposite to the ink-attached surface. Further, the heaters 100 can also be respectively arranged on both sides of the recording medium M.

[0094] In the drying area D, the ink composition attached to the recording medium is dried by the heater 100 to form a recording. Since the above-mentioned heater 100 is provided in the inkjet recording apparatus 1000, uneven heating of liquids such as ink attached to the recording medium M can be suppressed.

[0095] Figure 16 and Figure 17 is a schematic perspective view of the drying area D of the inkjet recording apparatus 1000 and its vicinity. In Figure 16 and Figure 17 example, nine heaters 100 are respectively mounted on the moving mechanism 300. In the inkjet recording apparatus 1000, as shown in the figure, when viewed along the conveyance direction SS of the recording medium M, they are arranged in a staggered manner so as not to easily generate gaps. In the inkjet recording apparatus 1000, although uneven heating caused by each heater 100 is suppressed, there is a part between the heaters 100 arranged side by side that is difficult to heat. Therefore, in the inkjet recording apparatus 1000, the plurality of heaters 100 are arranged so that when the recording medium M is conveyed, a portion that is difficult to be heated is not easily generated in the width direction.

[0096] 3. Oscillation of the drying device

[0097] In the inkjet recording apparatus 1000, the heater 100 can also be oscillated while maintaining a predetermined interval from the recording medium M by driving the moving mechanism 300. As the oscillation mode of the heater 100, examples include a reciprocating movement along the conveyance direction SS of the recording medium M ( Figure 17 schematically indicated by the "A" arrow mark in.).), a reciprocating movement along a direction crossing the conveyance direction SS of the recording medium M ( Figure 17 schematically indicated by the "B" arrow mark in.).), and a circular motion of rotating clockwise or counterclockwise ( Figure 17 schematically indicated by the "C" arrow mark in.).). These movement modes can be combined, and the movement amount is also arbitrary.

[0098] The heater 100 can further suppress uneven heating generated at portions between the heaters 100 arranged side by side by swinging while maintaining a predetermined interval from the recording medium M. In addition, since the inkjet recording apparatus 1000 is a serial printer as described above, the recording medium M is intermittently conveyed. Therefore, there are cases where the recording medium M is stationary in the drying area. In such a case, even when the recording medium M is in a stationary state, uneven heating on the recording medium M can be reduced by swinging the heater 100.

[0099] In addition, preferably, the moving mechanism 300 moves the plurality of heaters 100 back and forth by a distance equal to the conveyance distance when the recording medium M is conveyed once in the conveyance direction SS. For example, when the inkjet head 200 is mounted on a carriage, a printing pattern is drawn by the inkjet head 200 reciprocating in the width direction of the recording medium. Therefore, if the heater 100 does not reciprocate, depending on the conveyance amount of the recording medium M, there may be areas where the time staying directly below the heater 100 is longer and areas where the time staying directly below the heater 100 is shorter in each area of the recording medium M, which may cause uneven heating. By setting the moving mechanism 300 to move the plurality of heaters 100 back and forth by a distance equal to the conveyance distance each time the recording medium M is conveyed, the time staying directly below the heater 100 can be made equal in each area of the recording medium M, thereby suppressing uneven heating.

[0100] Although the above description has been made for the case where the inkjet recording apparatus 1000 is a serial printer, the inkjet recording apparatus may also be a line printer. Even in such a case, a recording object with reduced uneven heating can be easily obtained.

[0101] The above-described embodiments and modified embodiments are examples and are not limited to these. For example, the respective embodiments and the respective modified embodiments can be appropriately combined.

[0102] The present invention includes structures that are substantially the same as the structures described in the embodiments, such as structures with the same functions, methods, and results, or structures with the same purposes and effects. In addition, the present invention includes structures obtained by replacing non-essential parts of the structures described in the embodiments. In addition, the present invention includes structures that achieve the same effects as the structures described in the embodiments, or structures that can achieve the same purpose. In addition, the present invention includes structures obtained by adding known technologies to the structures described in the embodiments.

[0103] The following can be derived from the above description.

[0104] One mode of the drying device is that,

[0105] A drying device includes a heater configured at a predetermined interval relative to a recording medium and drying a liquid coated on the recording medium by high frequency. The drying device is characterized in that,

[0106] The heater has a first electrode and a second electrode. The first electrode is connected to a power source that outputs the high frequency, and the second electrode is connected to the power source that outputs the high frequency and is separated from the first electrode at a predetermined interval.

[0107] The distance between the end of the first electrode and the recording medium is longer than the distance between the central portion of the first electrode and the recording medium.

[0108] According to this drying device, when applying high frequency, the liquid on the recording medium can be heated with good uniformity. That is, by making the distance between the end of the first electrode and the recording medium longer than the distance between the central portion of the first electrode and the recording medium, the strong electromagnetic field generated near the end of at least one of the electrodes can be alleviated and the electromagnetic field can be dispersed toward a position away from both electrodes. Thereby, it is difficult to generate uneven heating on the recording medium opposed to one drying device.

[0109] In the above drying device, the following mode can also be adopted, that is,

[0110] When observed from the normal direction of the recording medium, the first electrode has a long side direction and a short side direction.

[0111] The radius of curvature of the end of the first electrode in the long side direction is larger than the radius of curvature of the end of the first electrode in the short side direction.

[0112] According to this drying device, since the end in the long side direction of the first electrode where the intensity of the electromagnetic field is more likely to concentrate when applying high frequency gently moves away from the second electrode, the effect of alleviating the concentration of the electromagnetic field intensity becomes significant. Thereby, it is further difficult to generate uneven heating on the recording medium opposed to one drying device.

[0113] In the above drying device, the following mode can also be adopted, that is,

[0114] A third electrode is provided between the first electrode and the second electrode.

[0115] The third electrode is not connected to the power source.

[0116] According to this drying device, the non-uniformity of the intensity of the electromagnetic field generated between the first electrode and the second electrode can be further reduced.

[0117] The recording device may also include a plurality of the above-described drying devices.

[0118] The plurality of drying devices are arranged side by side in a direction intersecting the conveying direction of the recording medium.

[0119] According to this recording device, it is possible to dry the liquid such as ink adhered to the recording medium with good uniformity.

[0120] In the above-described recording device, the following method may also be adopted, that is,

[0121] The drying device swings while maintaining the predetermined interval from the recording medium.

[0122] According to this recording device, it is possible to further reduce the uneven heating of the liquid on the recording medium. That is, by swinging the plurality of drying devices, it is possible to reduce the uneven heating between the area heated by one drying device and the area adjacent to the drying device that is not easily heated.

[0123] In the above-described recording device, the following method may also be adopted, that is,

[0124] The recording device is a serial inkjet recording device.

[0125] According to this recording device, even when the conveyance of the recording medium is intermittent and the recording medium is in a stationary state, by swinging the drying device, it is also possible to reduce the uneven heating on the recording medium.

[0126] Symbol Explanation

[0127] 10, 10a, 10b... First electrode; 20, 20a... Second electrode; 30... Coil; 40... Support member; 50... Inner conductor; 55... Electric wire; 60... Floating electrode; 100, 110, 120, 130... Heater; 200... Inkjet head; 300... Moving mechanism; M... Recording medium; r, R... Curvature radius; T... Conveying roller; G... Guide roller; P... Recording area; D... Drying area; SS... Conveying direction.

Claims

1. A drying device includes a heater configured to be spaced apart from a recording medium by a predetermined interval and dry a liquid coated on the recording medium by a high-frequency voltage. The drying device is characterized in that the heater has a first electrode and a second electrode. The first electrode is connected to a power supply that outputs the high-frequency voltage. The second electrode is connected to the power supply that outputs the high-frequency voltage and is disposed separately from the first electrode at a predetermined interval. The second electrode has a hollow elliptical shape that surrounds the first electrode when viewed from the normal direction of the recording medium and is disposed in a manner that prevents the induction of corona discharge. The distance between the end of the first electrode and the recording medium in the normal direction of the recording medium is longer than the distance between the central portion of the first electrode and the recording medium in the normal direction of the recording medium.

2. The drying device according to claim 1, characterized in that when viewed from the normal direction of the recording medium, the first electrode has a long side direction and a short side direction. The radius of curvature of the end of the first electrode in the long side direction is greater than the radius of curvature of the end of the first electrode in the short side direction.

3. The drying device according to claim 1 or 2, characterized in that a third electrode is provided between the first electrode and the second electrode. The third electrode is not connected to the power supply.

4. A recording device, characterized in that it includes a plurality of drying devices according to any one of claims 1 to 3. The plurality of drying devices are arranged side by side in a direction intersecting the conveying direction of the recording medium.

5. The recording device according to claim 4, characterized in that the drying device swings while maintaining the predetermined interval from the recording medium.

6. The recording device according to claim 5, characterized in that the recording device is a serial inkjet recording device.

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