JP2017220381A - Heating apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely and effectively improve heating efficiency in a heating apparatus.SOLUTION: A heating apparatus 1 includes: a power supply 11 generating an AC voltage; a heating section 12 irradiating a heating object 20 with an AC electric field M to heat the heating object 20, the AC electric field M being generated from an electrode pair 22 on which the AC voltage is applied; and a matching section 13 connected to the electrode pair 22 via a transmission path to match a power supply 11 side output impedance and a heating section 12 side input impedance. The heating section 12 includes a current increasing element 26 for increasing a current applied to the heating object 20 by the AC electric field M.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heating device and an image forming apparatus.

  High-frequency dielectric heating that heats a heated object in a non-contact state by irradiating the heated object with a high-frequency AC electric field in a heating apparatus is used. Such a heating device is used in various devices and systems, and is used as a drying device for drying ink on recording paper in an image forming apparatus such as an ink jet printer.

  For example, a device for dielectrically heating an object to be thawed such as frozen food, a plurality of electrodes arranged in a thawing chamber also serving as an electromagnetic shield, and conductors having different inductances between the three high-frequency power generation circuits and the electrodes A configuration in which a plurality of impedance matching circuits including the above are installed is disclosed (Patent Document 1).

  In order to improve the heating efficiency in a heating apparatus using high-frequency dielectric heating, it is necessary to efficiently and safely increase the current (applied current) applied to the object to be heated by the AC electric field. Although an increase in applied current is simply achieved by an increase in power supply voltage supplied to the electrode pair, an increase in power supply voltage may cause problems such as an increase in power consumption and heat generation in the transmission line.

  A heating apparatus using high-frequency dielectric heating usually includes a matching unit that matches the output impedance on the power source side and the input impedance on the load side (the heating unit side including the electrode pair and the object to be heated). Since the matching unit is configured to include various electronic devices, there is a possibility of malfunction due to the influence of the AC electric field if it is installed near the electrode pair. For this reason, the matching section needs to be installed at a location some distance from the electrode pair, and in many cases, the transmission path connecting the matching section and the electrode pair must be long. Since a long transmission line causes power loss, heat generation, etc., it is often impossible to simply increase the power supply voltage.

  This invention is made | formed in view of the above, Comprising: It aims at improving heating efficiency safely and efficiently.

  In order to solve the above-described problems and achieve the object, the present invention provides a power source for generating an alternating voltage and an object to be heated by irradiating an object to be heated with an alternating electric field generated from an electrode pair to which the alternating voltage is applied. A heating unit that heats an object to be heated; and a matching unit that is connected to the electrode pair via a transmission line and matches the output impedance on the power source side and the input impedance on the heating unit side, The heating apparatus includes a current increasing element that increases a current applied to the object to be heated by the alternating electric field.

  According to the present invention, it is possible to improve heating efficiency safely and efficiently.

FIG. 1 is a diagram illustrating a functional configuration of the heating device according to the first embodiment. FIG. 2 is a diagram illustrating a hardware configuration of a heating device according to a comparative example. FIG. 3 is a diagram illustrating an equivalent circuit of the heating device according to the comparative example. FIG. 4 is a diagram illustrating the relationship between the current magnitude and phase in the equivalent circuit shown in FIG. FIG. 5 is a diagram illustrating an ideal correlation among the correlations shown in FIG. FIG. 6 is a diagram illustrating a hardware configuration of the heating apparatus according to the first embodiment. FIG. 7 is a diagram illustrating an equivalent circuit of the heating device according to the first embodiment. FIG. 8 is a diagram illustrating frequency characteristics of input impedance according to the first embodiment. FIG. 9 is a diagram illustrating a hardware configuration of the heating apparatus according to the second embodiment. FIG. 10 is a diagram illustrating an equivalent circuit of the heating device according to the second embodiment. FIG. 11 is a diagram illustrating a hardware configuration of the heating apparatus according to the third embodiment. FIG. 12 is a diagram illustrating an equivalent circuit of the heating device according to the third embodiment.

(First embodiment)
FIG. 1 is a diagram illustrating a functional configuration of a heating apparatus 1 according to the first embodiment. The heating device 1 includes a power source 11, a heating unit 12, and a matching unit 13.

  The power supply 11 outputs a high-frequency AC voltage. The frequency of the alternating voltage only needs to be a value that can realize known high-frequency dielectric heating, and should be appropriately set according to the use environment, but can be a value of about 3 MHz to 300 MHz, for example.

  The heating unit 12 heats the article to be heated 20 by high frequency dielectric heating. The heating unit 12 includes an electrode pair 22 and a current increasing element 26. The electrode pair 22 generates a high-frequency AC electric field M when an AC voltage supplied from the power supply 11 is applied thereto. A plurality of electrode pairs 22 are usually provided, and each electrode pair 22 generates an alternating electric field M. By irradiating the object to be heated 20 with the AC electric field M, an applied current is generated in the object to be heated 20, and the object to be heated 20 is heated. The current increasing element 26 is an element that acts to increase the applied current generated in the object to be heated 20.

  The matching unit 13 is connected to the power source 11 and the heating unit 12 (electrode pair 22), and matches the impedance (output impedance) on the power source 11 side and the impedance (input impedance) on the heating unit 12 side. The matching unit 13 is configured using, for example, an electronic device that controls the two values to be equal based on the difference between the output impedance and the input impedance.

  Since the heating device 1 according to the present embodiment includes the current increasing element 26 that acts to increase the applied current generated in the article 20 to be heated, it depends only on the increase in the output voltage of the power supply 11. In addition, the heating efficiency of the article to be heated 20 can be improved.

  Here, with reference to the heating device 501 according to the comparative example shown in FIG. 2 and FIG. 3, conditions necessary for increasing the applied current generated in the article to be heated 20 will be described. FIG. 2 is a diagram illustrating a hardware configuration of the heating device 501 according to the comparative example. The heating device 501 according to the comparative example includes a power source 11, a heating unit 512, and a matching unit 13.

  The heating unit 512 includes a housing 21, a plurality of electrode pairs 22, a power supply wiring 23, and a ground wiring 24. The electrode pair 22, the power supply wiring 23, and the ground wiring 24 are arranged in a casing 21 having magnetic shielding properties. Each electrode pair 22 includes a pair of a positive electrode 22A and a negative electrode 22B, and is connected to the matching unit 13 via a power supply wiring 23 and is connected to GND via a ground wiring 24. Each electrode pair 22 generates an AC electric field when an AC voltage from the power supply 11 is applied through the power supply wiring 23. The object to be heated 20 (liquid such as ink on the recording paper) is heated by being irradiated with an alternating electric field generated from each electrode pair 22.

  The matching unit 13 includes a housing 31, a directional coupler 32, a variable capacitor 33, an internal inductor 34, and a microcontroller 35. The directional coupler 32, the variable capacitor 33, and the internal inductor 34 are disposed in a casing 31 having magnetic shielding properties. The directional coupler 32 is connected to the power source 11 and the variable capacitor 33 and outputs traveling waves and reflected waves. The variable capacitor 33 is connected to the directional coupler 32 and the internal inductor 34, and changes the capacitance according to a control signal from the microcontroller 35. Based on the traveling wave and the reflected wave, the microcontroller 35 changes the capacitance of the variable capacitor 34 so that the reflected wave becomes 0, for example.

  As described above, in order not to cause the AC electric field generated from the electrode pair 22 to cause the malfunction of the matching unit 13, the interval between the heating unit 512 and the matching unit 13 is increased, or the heating unit 512 and the matching unit 13 are It is necessary to cover the components with the casings 21 and 31. For this reason, the power supply wiring 23 often has to be long. As the power supply wiring 23 becomes longer, the power loss increases and the heating efficiency of the article to be heated 20 deteriorates. Further, if the output voltage of the power supply 11 is increased to compensate for power loss due to the power supply wiring 23, the power cost may increase or the heat generation of the power supply wiring 23 may become excessive.

  FIG. 3 is a diagram illustrating an equivalent circuit of the heating device 501 according to the comparative example. Capacitances C0 and C1 indicate two types of capacitances that the variable capacitor 33 has. An inductance L0 indicates the inductance of the internal inductor 34. The resistor R1 indicates the resistance of the power supply wiring 23. A capacitor C <b> 2 indicates a parasitic capacitance with respect to the GND of the power supply wiring 23. The inductance L1 indicates the inductance of the electrode pair 22 itself. A resistor R2 indicates the resistance of the electrode pair 22. A capacitance C3 indicates a parasitic capacitance of the electrode pair 22. A resistance R3 and a capacity C4 indicate the resistance and capacity of the article 20 to be heated. An object to be heated 20 that is mainly a dielectric is expressed as a series component of a resistor R3 and a capacitor C4. The impedance Z1 indicates the output impedance on the power supply 11 side. Impedance Z2 indicates the input impedance on the load side.

  A current I1 indicates a current flowing through the capacitor C2. A current I2 indicates a current flowing through the resistor R1. A current I3 indicates a current flowing through the inductance L1. A current I4 indicates a current flowing through the capacitor C3. A current I5 indicates a current flowing through the capacitor C4. The current I5 is an applied current applied to the object to be heated 20 by an alternating electric field generated by the electrode pair 22.

  In order to improve the heating efficiency of the article to be heated 20, the current I5 must be increased. In order to increase the current I5, the current I3 must be increased. In order to increase the current I3, it is necessary to increase the current I1 as much as possible and decrease the current I2 as much as possible. Hereinafter, the conditions of the currents I1 and I2 for increasing the current I3 will be described.

  FIG. 4 is a diagram illustrating the correlation between the magnitudes and phases of the currents I1, I2, and I3 in the equivalent circuit shown in FIG. FIG. 5 is a diagram illustrating an ideal correlation among the correlations shown in FIG. Here, when the currents I1, I2, and I3 are expressed as the following formulas (1), (2), and (3), the following formula (4) is derived.

I1 = | I1 | exp (jθ1) (1)
I2 = | I2 | exp (jθ2) (2)
I3 = | I3 | exp (jθ3) (3)
| I3 | ² = | I2-I1 | ² = | I2 | ² + | I1 | ² -2 | I1 || I2 | cos (θ2-θ1) (4)

  From equation (4), in order to increase | I3 |, it is ideal that ∠I2−∠I1 = θ2−θ1 = 180 ° and | I1 | be as large as possible. Further, it is ideal that ∠V2−∠I2 = 90 ° and the capacitance C2 be as large as possible. Further, it is ideal that ∠Z2≈90 ° (L property), that is, to make the absolute value | Z2 | of the input impedance as large as possible. | I2 | can be reduced by increasing | Z2 |. When | I3 | is constant, | I5 | becomes larger as | I4 | becomes smaller. Therefore, it is ideal to make | I4 | as small as possible, that is, make the capacitance C3 as small as possible.

  FIG. 6 is a diagram illustrating a hardware configuration of the heating apparatus 1 according to the first embodiment. The heating device 1 includes a power source 11, a heating unit 12, and a matching unit 13. The heating unit 12 according to the present embodiment includes an additional inductor 41 as a current increasing element 26, and a positive electrode 22A and a negative electrode 22B arranged in a staggered manner. The additional inductor 41 is an example of the current increasing element 26 that acts to reduce the current I2. The positive electrode 22A and the negative electrode 22B arranged in a staggered pattern are an example of the current increasing element 26 that acts to reduce the current I4.

  The heating unit 12 includes a casing 21 (first casing), a plurality of electrode pairs 22, a power supply wiring 23 (transmission path), a ground wiring 24, and an additional inductor 41. The electrode pair 22, the power supply wiring 23, the ground wiring 24, and the additional inductor 41 are arranged in the casing 21 having magnetic shielding properties.

  Each electrode pair 22 is composed of a set of a positive electrode 22A and a negative electrode 22B. Each electrode pair 22 is connected to the matching unit 13 via the power supply wiring 23 and the additional inductor 41, and is connected to GND via the ground wiring 24. Each electrode pair 22 generates an AC electric field M when an AC voltage supplied from the power supply 11 is applied through the power supply wiring 23 and the additional inductor 41.

  The positive electrode 22A and the negative electrode 22B according to the present embodiment are arranged in a staggered manner. The object to be heated 20 is heated by being irradiated with the alternating electric field M by passing between the positive electrode 22A and the negative electrode 22B that make a pair. The positive electrode 22A and the negative electrode 22B are arranged in a staggered manner, so that the electric capacity is smaller than when arranged in a straight line. That is, the positive electrode 22A and the negative electrode 22B arranged in a staggered manner act as elements (capacitance reducing elements) that reduce the parasitic capacitance of the electrode pair 22.

  The additional inductor 41 is an element (impedance increasing element) that acts so as to increase the impedance (input impedance Z2) of the entire heating unit 12. The specific structure of the additional inductor 41 is not particularly limited, but examples of the specific structure include an air-core solenoid type, a solenoid type having a core, and a toroidal type.

  The matching unit 13 includes a housing 31 (second housing), a directional coupler 32, a variable capacitor 33, an internal inductor 34, and a microcontroller 35. The directional coupler 32, the variable capacitor 33, and the internal inductor 34 are disposed in a casing 31 having magnetic shielding properties. The directional coupler 32 is connected to the power source 11 and the variable capacitor 33 and outputs traveling waves and reflected waves. The variable capacitor 33 is connected to the directional coupler 32 and the internal inductor 34, and changes the capacitance according to a control signal from the microcontroller 35. The internal inductor 34 is connected to the variable capacitor 33 and the power supply wiring 23. The microcontroller 35 includes a microcomputer or the like, and generates and outputs a control signal that changes the variable capacitor 34 based on the traveling wave and the reflected wave from the directional coupler 32. For example, the microcontroller 35 changes the capacitance of the variable capacitor 33 so that the reflected wave becomes zero.

  FIG. 7 is a diagram illustrating an equivalent circuit of the heating apparatus 1 according to the first embodiment. Capacitances C0 and C1 indicate two types of capacitances that the variable capacitor 33 has. An inductance L0 indicates the inductance of the internal inductor 34. The resistor R1 indicates the resistance of the power supply wiring 23. A capacitor C <b> 2 indicates a parasitic capacitance with respect to the GND of the power supply wiring 23. An inductance LA indicates the inductance of the additional inductor 41. The inductance L1 indicates the inductance of the electrode pair 22 itself. A resistor R2 indicates the resistance of the electrode pair 22. A capacitance C3 indicates a parasitic capacitance of the electrode pair 22. The parasitic capacitance C3 of the electrode pair 22 composed of the positive electrode 22A and the negative electrode 22B arranged in a staggered manner as in the present embodiment is based on the parasitic capacitance of the electrode pair when the positive electrode and the negative electrode are arranged linearly. Get smaller. A resistance R3 and a capacity C4 indicate the resistance and capacity of the article 20 to be heated. An object to be heated 20 that is mainly a dielectric is expressed as a series component of a resistor R3 and a capacitor C4. The impedance Z1 indicates the output impedance on the power supply 11 side. Impedance Z2 indicates the input impedance on the load side.

  A current I1 indicates a current flowing through the capacitor C2. A current I2 indicates a current flowing through the resistor R1. A current I3 indicates a current flowing through the inductance L1. A current I4 indicates a current flowing through the capacitor C3. A current I5 indicates a current flowing through the capacitor C4. The current I5 is an applied current applied to the object to be heated 20 by the alternating electric field M generated by the electrode pair 22.

  A directional coupler 32 is connected between the power supply 11 and the variable capacitors C0 and C1. The directional coupler 32 has four ports (power input, power output, reflected wave output, and traveling wave output). The microcontroller 35 controls the variable capacitors C0 and C1 based on the reflected wave and the traveling wave. For example, the microcontroller 35 switches the variable capacitors C0 and C1 so that the voltage corresponding to the reflected wave becomes as small as possible.

  FIG. 8 is a diagram illustrating frequency characteristics of the input impedance Z2 according to the first embodiment. In the figure, the horizontal axis of the graph indicates the frequency of the voltage (power) applied to the electrode pair 22. In the figure, it is shown that the input impedance Z2 is minimum at the frequency fs and the input impedance Z2 is maximum at the frequency fp. At the frequency fs, a series resonance in which a resonance current circulates between the inductance L1 and the capacitors C3 and C4 occurs. At the frequency fp, a parallel resonance in which a resonance current circulates between the inductance L1 and the capacitors C2, C3, and C4 occurs.

  In order to reduce the current I2, the input impedance Z2 may be increased. Therefore, the structure of the electrode pair 22, that is, the inductances LA and L 1 and the capacitors C 2, C 3 and C 4 are set so that the frequency (power operating frequency) of the voltage (power) output from the power source 11 and the frequency fp are as close as possible. Just design. When the power supply operating frequency exists between the frequency fs and the frequency fp of the input impedance Z2, the frequency fp moves to the low frequency side when the value of the inductance LA is increased. By adjusting the inductance LA based on such characteristics (designing the additional inductor 41), the frequency fp at which parallel resonance occurs can be brought close to the power supply operating frequency.

  The input impedance Z2 can be increased by adding the additional inductor 41 having an appropriate inductance LA to the heating unit 12 (between the power supply wiring 23 and the electrode pair 22) as described above. Thereby, the current I2 flowing through the power supply wiring 23 can be decreased and the current I3 can be increased. Thereby, the current I5 can be increased as compared with the case where the additional inductor 41 is not provided (the heating device 501 according to the comparative example), and the heating efficiency can be improved safely and efficiently.

  Further, by using the positive electrode 22A and the negative electrode 22B arranged in a staggered manner as described above, the parasitic capacitance C3 of the electrode pair 22 becomes relatively small. Thereby, the current I4 flowing through the electrode pair 22 can be reduced without reducing the current I3. Thereby, the current I5 can be increased as compared with the case where the positive electrode and the negative electrode are linearly arranged, and the heating efficiency can be improved safely and efficiently.

(Second Embodiment)
FIG. 9 is a diagram illustrating a hardware configuration of the heating apparatus 101 according to the second embodiment. FIG. 10 is a diagram illustrating an equivalent circuit of the heating apparatus 101 according to the second embodiment. The heating unit 112 of the heating device 101 according to the present embodiment is obtained by replacing the additional inductor 41 of the heating unit 12 of the heating device 1 according to the first embodiment with a transformer 42. The transformer 42 according to the present embodiment is an example of the current increasing element 26, and the input impedance Z <b> 2 is increased similarly to the additional inductor 41 according to the first embodiment, that is, the power supply wiring 23 (resistor R <b> 1). It is an element (impedance increasing element) that acts to reduce the flowing current I2.

  The transformer 42 is disposed between the power supply wiring 23 and the electrode pair 22. The turns ratio of the transformer 42 is N1: N2 (primary side: secondary side), the primary side voltage is V1, the primary side current is I2, the secondary side voltage is V2, and the secondary side current is When I20, the relationship of the following formulas (5) and (6) is established between the voltages V1 and V2 and the currents I2 and I20.

(N1 / N2) · V2 = V1 (5)
(N2 / N1) · I20 = I2 (6)

Here, if the equivalent circuit constant of the electrode pair 22 and the equivalent circuit constant of the object to be heated 20 are the same, the power consumed by the electrode pair 22 and the object to be heated 20 is the same regardless of the turns ratio of the transformer 42. Therefore, the value of the current I20 is constant regardless of the turns ratio. Therefore, if N1> N2 from Expression (6), I20> I2, and the current I2 flowing through the power supply wiring 23 (resistor R1) becomes small. That is, if N1> N2, because it appears large in input impedance Z2 is (N1 / ^{N2) 2-fold} when viewed from the primary side of the transformer 42, the current I2 flowing in the resistor R1 will be the throttled.

  Also according to the present embodiment, the current I5 can be increased similarly to the first embodiment, and the heating efficiency can be improved safely and efficiently.

  In the first embodiment and the second embodiment, the additional inductor 41 and the transformer 42 are illustrated as the current increasing element 26 that acts to reduce the current I2, and the current I4 is reduced. The positive electrode 22A and the negative electrode 22B arranged in a zigzag manner are illustrated as the current increasing elements 26 to be performed. However, the specific configurations of the current increasing element 26 that operates to decrease the current I2 and the current increasing element 26 that operates to decrease the current I4 are not limited to the above, and a known or new configuration is appropriately used. Can be constructed.

(Third embodiment)
FIG. 11 is a diagram illustrating a hardware configuration of the heating apparatus 201 according to the third embodiment. FIG. 12 is a diagram illustrating an equivalent circuit of the heating device 201 according to the third embodiment. The heating unit 212 of the heating device 201 according to the present embodiment is obtained by adding an additional capacitor 43 to the heating unit 12 of the heating device 1 according to the first embodiment. The additional capacitor 43 according to the present embodiment is an example of the current increasing element 26, and is an element (capacitance increasing element) that acts to increase the parasitic capacitance with respect to the GND of the power supply wiring 23, and the current I1 that flows through the capacitor C2 is increased. Acts to enlarge.

  One end of the additional capacitor 43 is connected to a connection portion between the power supply wiring 23 and the additional inductor 41 (or the electrode pair 22 when the additional inductor 41 is not provided). As shown in FIG. 12, the capacitor C <b> 5 of the additional capacitor 43 is arranged to be parallel to the capacitor C <b> 2 of the power supply wiring 23. Thereby, the current I1 flowing through the capacitor C2 can be increased.

  According to the present embodiment, the current I5 can be further increased as compared with the case of the first embodiment, and the heating efficiency can be improved.

  In the third embodiment, the additional capacitor 43 is exemplified as the current increasing element 26 that operates to increase the current I1, but the specific configuration of the current increasing element 26 that operates to increase the current I1 is illustrated. Is not limited to the above, and can be constructed by appropriately using a known or novel configuration.

  The heating devices 1, 101, 201 and their modifications according to the above-described embodiment are used in various devices and systems, and various substances can be used as the object to be heated 20. For example, the heating devices 1, 101, and 201 can be mounted on an image forming apparatus such as an ink jet printer and used as a drying device that heats and dries liquid such as ink and coating agent adhering to the recording paper. Moreover, the to-be-heated material 20 is not restricted to a sheet form, For example, it is also possible to apply the said heating apparatus to the 3D printer etc. which use the three-dimensional molded item as the to-be-heated material 20.

  Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1,101,201,501 Heating device 11 Power supply 12,112,212,512 Heating part 13 Matching part 20 Object to be heated 21 (First) housing 22 Electrode pair 23 Feeding wiring 24 Grounding wiring 22A Positive electrode 22B Negative electrode 26 Current Increasing Element 31 (Second) Housing 32 Directional Coupler 33 Variable Capacitance 34 Internal Inductor 35 Microcontroller 41 Additional Inductor 42 Transformer 43 Additional Capacitor M AC Electric Field

Japanese Patent No. 4177963

Claims (11)

A power source for generating an alternating voltage;
A heating unit that heats the object to be heated by irradiating the object to be heated with an AC electric field generated from the electrode pair to which the AC voltage is applied;
A matching unit that is connected to the electrode pair via a transmission line and matches the output impedance on the power source side and the input impedance on the heating unit side,
With
The heating unit includes a current increasing element that increases a current applied to the object to be heated by the AC electric field.
Heating device. The current increasing element includes an impedance increasing element that increases the input impedance.
The heating apparatus according to claim 1. The impedance increasing element is an inductor connected to the transmission line.
The heating apparatus according to claim 2. The impedance increasing element is a transformer connected to the transmission line.
The heating apparatus according to claim 2. The current increasing element includes a capacitance decreasing element that decreases a parasitic capacitance of the electrode pair.
The heating apparatus of any one of Claims 1-4. The capacitance reducing element comprises the positive electrode and the negative electrode that constitute the electrode pair and are arranged in a staggered manner,
The object to be heated passes between a pair of the positive electrode and the negative electrode,
The heating apparatus according to claim 5. The current increasing element includes a capacitance increasing element that increases a parasitic capacitance with respect to GND of the transmission line.
The heating device according to any one of claims 1 to 6. The heating unit includes a first housing that houses the electrode pair and the transmission path and has magnetic shielding properties,
The heating apparatus of any one of Claims 1-7. The current increasing element is disposed in the first housing;
The heating apparatus according to claim 8. The matching unit includes a variable capacitor, an internal inductor connected between the variable capacitor and the transmission line, and a directional coupling that outputs a traveling wave and a reflected wave connected between the power source and the variable capacitor. And a second housing having a magnetic shielding property and containing at least the variable capacitor, the internal inductor, and the directional coupler, and a control element that changes the variable capacitance based on the traveling wave and the reflected wave. Including the body,
The heating device according to any one of claims 1 to 9. The liquid attached to the medium is heated by the heating device according to any one of claims 1 to 10.
Image forming apparatus.

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