Dielectric heating device

Abstract

The dielectric heating device includes: two heating electrodes spaced apart and facing each other; a heating chamber disposed between the two heating electrodes and serving as a space for placing an object to be heated; a high-frequency power supply that supplies high-frequency power to the two heating electrodes such that the phase difference between the voltages applied to the two heating electrodes is 180°; and a control unit that individually adjusts the voltages applied to the two heating electrodes from the high-frequency power supply.

Description

Technical Field

[0001] This invention relates to a dielectric heating device. Background Technology

[0002] It is known that a dielectric heating device heats an object disposed in a heating chamber by applying a voltage to at least one of two opposing electrodes.

[0003] In such dielectric heating devices, it is known to use counter electrodes with a balanced circuit that includes the same electric field distribution in both positive and negative states as the load-side circuit (see, for example, Japanese Patent No. 2884554). Accordingly, by applying voltages with a phase difference of 180° to the two counter electrodes, it is possible to suppress the difference in electric field intensity within the heated object, thereby enabling the heated object to be heated uniformly as a whole. Summary of the Invention

[0004] In a dielectric heating device where the positions of two opposing electrodes (e.g., an upper electrode and a lower electrode) are fixed, the distance from the heated object to the upper electrode may sometimes differ from the distance from the heated object to the lower electrode. In this case, even with heating control using the aforementioned balancing circuit, the electric field strength exerted by the upper electrode on the heated object may differ from that exerted by the lower electrode on the heated object. If such a difference in electric field strength occurs, it may be impossible to heat the heated object uniformly.

[0005] The purpose of this disclosure is to provide a dielectric heating device capable of uniformly heating the entire object being heated.

[0006] One aspect of the dielectric heating device disclosed herein includes: two heating electrodes spaced apart and facing each other; a heating chamber disposed between the two heating electrodes and serving as a space for placing an object to be heated; a high-frequency power supply that supplies high-frequency power to the two heating electrodes such that the phase difference between the voltages applied to the two heating electrodes is 180°; and a control unit that individually adjusts the voltages applied from the high-frequency power supply to the two heating electrodes. Attached Figure Description

[0007] Figure 1 This is a diagram showing the overall structure of the dielectric heating device.

[0008] Figure 2 This is a diagram showing the structure of the matching circuit.

[0009] Figure 3A It is a coordinate graph representing the changes in electrode voltage applied to the upper and lower electrodes.

[0010] Figure 3BIt is a coordinate graph representing the change in the inter-electrode voltage generated between the upper and lower electrodes.

[0011] Figure 4A This is a diagram showing a heating chamber with a heated object T.

[0012] Figure 4B This is a diagram showing a heating chamber with two objects T overlapping each other.

[0013] Figure 4C This is a diagram showing a heating chamber with four heated objects T arranged in an overlapping configuration.

[0014] Figure 5 It is a coordinate graph showing the changes in the electrode voltage applied to the upper and lower electrodes after the voltage ratio is adjusted.

[0015] Figure 6 This is an external view of the dielectric heating device involved in the first example.

[0016] Figure 7 This is an external view of the dielectric heating device involved in the second example.

[0017] Figure 8 This is an external view of the dielectric heating device involved in the third example.

[0018] Figure 9 This is an external view of the dielectric heating device involved in the fourth example.

[0019] Figure 10 This is an external view of the dielectric heating device involved in the fifth example.

[0020] Figure 11 This is an external view of the dielectric heating device involved in the sixth case.

[0021] Figure 12A This is a diagram showing the overall structure of the dielectric heating device involved in the modified example.

[0022] Figure 12B This is a diagram showing the structure of the matching circuit involved in the modified example. Detailed Implementation

[0023] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in relation to the drawings, the same or equivalent elements will be labeled with the same reference numerals, and repeated descriptions will be omitted.

[0024] (Overview of the dielectric heating device)

[0025] The dielectric heating device 100 according to this embodiment will be described. Figure 1 This is a diagram showing the overall structure of the dielectric heating device 100. Figure 2This diagram illustrates the structure of matching circuits 104A and 104B. The dielectric heating device 100 applies a high-frequency electric field to the food or other heated items to perform heating, defrosting, or other similar processes.

[0026] like Figure 1 As shown, the dielectric heating device 100 includes a heating chamber 101, a drive circuit 102, and a control unit 105. The heating chamber 101 is a metal box-shaped structure with an internal space capable of accommodating an object to be heated. The internal space of the heating chamber 101 has an opening at the front and can be opened and closed via an opening and closing door (not shown). Figure 1 The diagram schematically shows the heating chamber 101 as viewed from the front. Figure 1 The upper, lower, left, right, front, and deep sides of the paper correspond to the upper, lower, left, right, front, and rear sides of the dielectric heating device 100 (i.e., the heating chamber 101), respectively. The metal heating chamber 101 is grounded through a grounding wire 109, etc.

[0027] The heating chamber 101 contains two heating electrodes 110 and a heating chamber 113. The two heating electrodes 110 are spaced apart and facing each other. As an example, the two heating electrodes 110 are an upper electrode 111 and a lower electrode 112 facing each other in the vertical direction. The upper electrode 111 and the lower electrode 112 are quadrilateral flat plates extending in the front-back and left-right directions and are arranged in a parallel manner. The heating chamber 113 is a space between the two heating electrodes 110 (upper electrode 111 and lower electrode 112) that can accommodate multiple objects to be heated.

[0028] The drive circuit 102 includes a high-frequency power supply 103 and matching circuits 104A and 104B. The high-frequency power supply 103 is a power supply circuit that generates high-frequency power to supply to the two heating electrodes 110. Specifically, the high-frequency power supply 103 supplies high-frequency power to the two heating electrodes 110 in such a way that the phase difference between the voltages applied to the two heating electrodes 110 is 180°. The high-frequency power supply 103 includes an oscillator 131, a phase shifter 132, variable attenuators 133A and 133B, and amplifiers 134A and 134B.

[0029] Oscillator 131 is connected to the aforementioned grounding wire 109 and emits a voltage signal with a frequency band from HF to VHF. The voltage signal emitted by oscillator 131 is input to variable attenuators 133A and 133B, which are connected in parallel with oscillator 131. The voltage signal input to variable attenuator 133B is phase-shifted by 180° by phase shifter 132 connected between variable attenuator 133B and high-frequency power supply 103. Therefore, the phase shift difference between the voltage signals input to variable attenuators 133A and 133B is 180°.

[0030] The voltage signal attenuated to an appropriate level by the variable attenuator 133A is amplified to the desired power by the amplifier 134A and sent to the matching circuit 104A. The voltage signal attenuated to an appropriate level by the variable attenuator 133B is amplified to the desired power by the amplifier 134B and sent to the matching circuit 104B. Thus, the voltage signals sent to the matching circuits 104A and 104B are amplified to the same level of power and have a phase difference of 180°.

[0031] like Figure 2 As shown, for the matching circuit 104A, the input side is connected to the amplifier 134A, and the output side is connected to the upper electrode 111. The matching circuit 104A includes a variable coil 201 and variable capacitors 202 and 203. In the matching circuit 104A, the variable coil 201 and the variable capacitor 202 are connected in series with the output of the high-frequency power supply 103, and the variable capacitor 203 is connected in parallel with the output of the high-frequency power supply 103. The variable capacitor 203 is connected to the aforementioned ground wire 109.

[0032] Matching circuit 104A adjusts the values ​​of variable coil 201 and variable capacitors 202 and 203 to match the input impedance of matching circuit 104A with the output impedance of amplifier 134A. This ensures that the impedance of the upper electrode 111 side as observed from the high-frequency power supply 103 (specifically amplifier 134A) remains constant, allowing for efficient supply of a voltage signal to the upper electrode 111 side.

[0033] For the matching circuit 104B, its input side is connected to the amplifier 134B, and its output side is connected to the lower electrode 112. The matching circuit 104B, with the same structure as the matching circuit 104A, ensures that its input impedance matches the output impedance of the amplifier 134B. This allows for a constant impedance at the lower electrode 112 as observed from the high-frequency power supply 103 (specifically, the amplifier 134B), enabling efficient supply of a voltage signal to the lower electrode 112.

[0034] In the drive circuit 102, the matched circuits 104A and 104B supply an impedance-matched voltage to the capacitor formed by the upper electrode 111 and the lower electrode 112. As a result, a high-frequency electric field is generated between the upper electrode 111 and the lower electrode 112, which dielectrically heats the object to be heated that is disposed between the upper electrode 111 and the lower electrode 112.

[0035] Figure 3A This is a coordinate graph representing the changes in electrode voltage applied to the upper electrode 111 and the lower electrode 112. Figure 3AIn the example, the voltage variation applied by the high-frequency power supply 103 to the upper electrode 111 and the lower electrode 112 represents a sinusoidal wave with an amplitude displacement of "-0.5" to "+0.5" within one cycle. However, the phase shift between the applied voltage of the upper electrode 111 and the applied voltage of the lower electrode 112 is 180°.

[0036] Figure 3B This is a coordinate graph representing the change in the inter-electrode voltage generated between the upper electrode 111 and the lower electrode 112. The inter-electrode voltage is the difference between the applied voltage of the upper electrode 111 and the applied voltage of the lower electrode 112. Figure 3B express Figure 3A The change in the voltage between the upper electrode 111 and the lower electrode 112 is shown. Since the amplitude of this voltage change is twice that of the applied voltages of the upper electrode 111 and the lower electrode 112, it represents a sinusoidal wave with an amplitude displacement of "-1.0" to "+1.0" within one period.

[0037] In this dielectric heating device 100, the high-frequency power supply 103 applies voltage to the two heating electrodes 110 such that the phase difference between the voltages applied to the two heating electrodes 110 is 180°. This balanced circuit heating control, compared to an unbalanced circuit heating control that applies voltage to only one of the two heating electrodes 110, can suppress the maximum voltage applied to a single heating electrode 110 and generate a larger inter-electrode voltage.

[0038] The control unit 105 is an electronic component responsible for controlling the heating of the dielectric heating device 100, and is composed of, for example, a microcomputer or electronic circuits. The control unit 105 individually adjusts the voltage applied from the high-frequency power supply 103 to the two heating electrodes 110.

[0039] (Voltage ratio adjusted by the control unit)

[0040] In this embodiment, as described above, the two heating electrodes 110 include an upper electrode 111 located above the heating chamber 113 and a lower electrode 112 located below the heating chamber 113. The control unit 105 adjusts the voltage ratio of the upper electrode 111 and the lower electrode 112 based on the height (i.e., the vertical length) of the object to be heated disposed in the heating chamber 113.

[0041] Reference Figures 4A to 4C The voltage ratio of the upper electrode 111 and the lower electrode 112 adjusted by the control unit 105 will be explained. Figure 4A This is a diagram showing a heating chamber 101 configured with a heated object T. Figure 4B This is a diagram showing a heating chamber 101 with two objects T being heated overlapping. Figure 4CThis is a diagram showing a heating chamber 101 with four heated objects T arranged in an overlapping configuration.

[0042] In the following description, the distance between the two heating electrodes 110 (i.e., the distance between the upper electrode 111 and the lower electrode 112) is defined as distance H1. The height of a heated object T is defined as distance H2. The magnitude of the voltage of the upper electrode 111 is defined as voltage VU. The magnitude of the voltage of the lower electrode 112 is defined as voltage VL.

[0043] exist Figure 4A In the example shown, a heated object T is disposed on the lower electrode 112 inside the heating chamber 113. When such a heated object T is heated inside the heating chamber 113, the control unit 105 controls the high-frequency power supplied to the upper electrode 111 and the lower electrode 112 respectively, and adjusts the voltage ratio of the upper electrode 111 and the lower electrode 112 in a manner that satisfies the following (Equation 1).

[0044] 0.25*H2 / H1≤VL / (VL+VU)≤0.75*H2 / H1···(Equation 1)

[0045] like Figure 3A As illustrated, the control unit 105 controls the high-frequency power supplied to each heating electrode 110 in such a way that the phase difference between the voltages applied to the two heating electrodes 110 is 180°. However, the control unit 105 maintains Figure 3B The illustrated inter-electrode voltage is used to change the ratio of voltage VU and voltage VL in a manner that satisfies (Equation 1).

[0046] Here, distance H1 is a preset fixed value. On the other hand, distance H2 varies depending on the object T being heated, which is disposed within the heating chamber 113. In other words, the target ratio of voltage VL and voltage VU varies depending on the object T being heated, which is disposed within the heating chamber 113. Within the heating chamber 113, the position where the electric field acting from the upper electrode 111 and the electric field acting from the lower electrode 112 are balanced is called the electric field reference position. Adjusting the voltage ratio by (Equation 1) is equivalent to adjusting the electric field reference position.

[0047] In Equation 1, "0.25 * H2 / H1" represents the lower limit of the allowable width H3 within the heating chamber 113, which allows for the setting of the electric field reference position. Specifically, when viewed from the vertical center C1 of a heated object T, the lower limit of the allowable width H3 is located at a distance equivalent to 1 / 4 of the height of the heated object T (i.e., the distance from H2). On the other hand, "0.75 * H2 / H1" represents the upper limit of the allowable width H3. Specifically, when viewed from the vertical center C1, the upper limit of the allowable width H3 is located at a distance equivalent to 1 / 4 of the distance from H2.

[0048] In other words, the allowable width H3 of the electric field reference position based on (Equation 1) becomes the width in the vertical direction centered at the vertical center C1, equivalent to half the distance from H2. If the control unit 105 adjusts the ratio of voltage VU and voltage VL in a manner satisfying (Equation 1), the electric field reference position falls within the allowable width H3. Thus, in a heated object T, an electric field that is approximately balanced on both the upper and lower parts is applied with reference to the vertical center C1. Therefore, uneven heating does not occur on the upper and lower parts of a heated object T, and the entire heated object T can be heated evenly.

[0049] exist Figure 4B In the example shown, two objects T to be heated are stacked vertically on the lower electrode 112 within the heating chamber 113. When these two objects T are heated within the heating chamber 113, the control unit 105 controls the high-frequency power supplied to the upper electrode 111 and the lower electrode 112 respectively, adjusting the voltage ratio of the upper electrode 111 and the lower electrode 112 in a manner that satisfies the following (Equation 2).

[0050] 0.5*H2 / H1≤VL / (VL+VU)≤1.5*H2 / H1···(Equation 2)

[0051] In Equation 2, "0.5 * H2 / H1" represents the lower limit of the allowable width H3 within the heating chamber 113, which allows for the setting of the electric field reference position. Specifically, when viewed from the vertical center C2 of the two heated objects T, the lower limit of the allowable width H3 is located at a distance equivalent to half the height of the heated object T (i.e., the distance from H2). On the other hand, "1.5 * H2 / H1" represents the upper limit of the allowable width H3. Specifically, when viewed from the vertical center C2, the upper limit of the allowable width H3 is located at a distance equivalent to half the distance from H2.

[0052] In other words, the allowable width H3 of the electric field reference position based on (Equation 2) becomes the width in the vertical direction centered on the vertical center C2, corresponding to a distance of H2. If the control unit 105 adjusts the ratio of voltage VU and voltage VL in a manner that satisfies (Equation 2), the electric field reference position falls within the allowable width H3. As a result, a roughly balanced electric field acts on both the heated object T above the vertical center C2 and the heated object T below the vertical center C2. Therefore, uneven heating does not occur between the upper and lower heated objects T, and the entirety of the two heated objects T can be heated evenly.

[0053] The number of heated objects T in Equations 1 and 2 above differs. In other words, as shown in Equations 1 and 2, if the number of heated objects T is different, the constants set in the formula representing the lower limit position of the allowable width H3 and the formula representing the upper limit position of the allowable width H3 vary depending on the number of heated objects T. For example, in Equation 1, the constant representing the lower limit position of the allowable width H3 is "0.25", but in Equation 2, the constant representing the lower limit position of the allowable width H3 is "0.5".

[0054] Therefore, in Equations 1 and 2, by setting the number of heated objects T to n such variables, Equations 1 and 2 derive a common formula (Equation 3). That is, when n identical heated objects T are heated in n overlapping layers in the heating chamber 113, the control unit 105 controls the high-frequency power supplied to the upper electrode 111 and the lower electrode 112 respectively to adjust the voltage ratio of the upper electrode 111 and the lower electrode 112 in a manner that satisfies the following formula (Equation 3).

[0055] 0.25*n*H2 / H1≤VL / (VL+VU)≤0.75*n*H2 / H1···(Equation 3)

[0056] Furthermore, if “n=1” is substituted into (Equation 3), it becomes the same as (Equation 1); if “n=2” is substituted into (Equation 2), it becomes the same as (Equation 2).

[0057] In Equation 3, "0.25 * n * H2 / H1" represents the lower limit of the allowable width H3 within the heating chamber 113, which allows for the setting of the electric field reference position. Specifically, when viewed from the center C3 in the vertical direction of the n heated objects T, the lower limit of the allowable width H3 is located below by a distance equal to the height of the heated object T (i.e., distance H2) multiplied by "0.25 * n". On the other hand, "0.75 * n * H2 / H1" represents the upper limit of the allowable width H3. Specifically, when viewed from the center C3 in the vertical direction, the upper limit of the allowable width H3 is located above by a distance equal to the distance H2 multiplied by "0.25 * n".

[0058] exist Figure 4C In the example shown, within the heating chamber 113, four heated objects T are arranged vertically overlapping on the lower electrode 112, thus "n = 4". In this case, when viewed from the vertical center C3 of the four heated objects T, the lower limit of the width H3 is allowed to be located below by a distance equivalent to H2. When viewed from the vertical center C3, the upper limit of the width H3 is allowed to be located above by a distance equivalent to H2.

[0059] In other words, the allowable width H3 of the electric field reference position based on (Equation 3) becomes a width in the vertical direction equivalent to "2 * 0.25 * n" centered on the vertical center C3. If the control unit 105 adjusts the ratio of voltage VU and voltage VL in a manner that satisfies (Equation 3), the electric field reference position falls within the allowable width H3. Therefore, as described above, the entire assembly of n heated objects T can be heated evenly.

[0060] In this embodiment, the control unit 105 adjusts the ratio of voltage VU and voltage VL in a manner that ensures the electric field reference position is approximately aligned with the vertical center of the allowable width H3, regardless of the number of n objects. This results in a more balanced electric field between the portion of the n heated objects T located above the vertical center C3 and the portion located below the vertical center C3. Consequently, the entire group of n heated objects T can be heated more evenly. Of course, if the electric field reference position falls within the allowable width H3, it can also deviate from the vertical center of the allowable width H3.

[0061] (Method for adjusting the voltage ratio)

[0062] For example, during heating control of the dielectric heating device 100, the control unit 105 calculates a target ratio of voltage VU and voltage VL using any one of the aforementioned (Equations 1) to (Equations 3). The control unit 105 adjusts the electrode voltages applied to the upper electrode 111 and the lower electrode 112 in a manner that makes voltage VU and voltage VL consistent with the target ratio.

[0063] In this embodiment, as described above, the high-frequency power supply 103 includes two amplifiers 134A and 134B, which output voltages to the two heating electrodes 110 respectively based on the high-frequency signal from the oscillator 131. The control unit 105 adjusts the voltage applied to the two heating electrodes 110 individually by adjusting the output voltages of the two amplifiers 134A and 134B separately. (Refer to...) Figure 1 The specific method for adjusting such a voltage ratio will be explained.

[0064] A first method for adjusting the voltage ratio will be described. As previously mentioned, the high-frequency power supply 103 includes two variable attenuators 133A and 133B, which are used to attenuate the high-frequency signals input to the two amplifiers 134A and 134B, respectively. The control unit 105 adjusts the output voltage of the two amplifiers 134A and 134B individually by adjusting the attenuation of the high-frequency signals based on the two variable attenuators 133A and 133B.

[0065] For example, the control unit 105 increases the attenuation of one of the variable attenuators 133A and 133B and decreases the attenuation of the other in a manner that makes the voltages VU and VL a target ratio. As a result, the output voltage of one of the two amplifiers 134A and 134B increases, and the output voltage of the other decreases. Thus, the electrode voltages applied to the upper electrode 111 and the lower electrode 112 are approximately consistent with the target ratio of voltages VU and VL.

[0066] A second method for adjusting the voltage ratio will be described. In the two amplifiers 134A and 134B, the amplification rate of the input high-frequency signal varies depending on the magnitude of the drive voltage supplied by the control unit 105. Therefore, the control unit 105 adjusts the output voltage of the two amplifiers 134A and 134B individually by adjusting the drive voltage used to operate the two amplifiers 134A and 134B.

[0067] For example, the control unit 105 increases the driving voltage of one of the input amplifiers 134A and 134B and decreases the driving voltage of the other in a manner that makes the voltages VU and VL a target ratio. As a result, the output voltage of one of the two amplifiers 134A and 134B increases, and the output voltage of the other decreases. Thus, the electrode voltages applied to the upper electrode 111 and the lower electrode 112 are approximately consistent with the target ratio of voltages VU and VL.

[0068] According to the first and second methods described above, the impedance matching between amplifier 134A and upper electrode 111 will not be compromised, and the impedance matching between amplifier 134B and lower electrode 112 will not be compromised, so that voltage VU and voltage VL can be adjusted to match the target ratio.

[0069] Here, refer to Figure 5 The changes in the electrode voltage applied to the upper electrode 111 and the lower electrode 112 after the above-mentioned voltage ratio adjustment will be explained. Figure 5 This is a coordinate graph showing the changes in the electrode voltage applied to the upper electrode 111 and the lower electrode 112 after the voltage ratio is adjusted. For example, in Figure 4B In this configuration, the two objects T to be heated, positioned within the heating chamber 113, are closer to the lower electrode 112 than the upper electrode 111. Therefore, the electric field generated by the upper electrode 111 is less likely to act on the two objects T than the electric field generated by the lower electrode 112.

[0070] In such a case, the control unit 105 calculates a target ratio where the voltage VU is greater than the voltage VL based on (Equation 2). For example, the control unit 105 calculates "0.7:0.3" as the target ratio of voltage VU to voltage VL. In this case, Figure 5 The electrode voltage illustrated is applied to the upper electrode 111 and the lower electrode 112.

[0071] exist Figure 5 In the example, with Figure 3A Similar to the previous example, the applied voltage (VU) of the upper electrode 111 and the applied voltage (VL) of the lower electrode 112 are 180° out of phase. However, voltage VU represents a sinusoidal wave with an amplitude displacement of -0.7 to +0.7 within one period, while voltage VL represents a sinusoidal wave with an amplitude displacement of -0.3 to +0.3 within one period. In this case, the change in the inter-electrode voltage between the upper electrode 111 and the lower electrode 112 is also similar to... Figure 3B The same indicates a sinusoidal wave with an amplitude displacement of "-1.0" to "+1.0" within one period.

[0072] Therefore, the electric field generated by the upper electrode 111 is greater than the electric field generated by the lower electrode 112. Furthermore, the electric field generated by the upper electrode 111 acts on the two heated objects T with the same intensity as the electric field generated by the lower electrode 112. Thus, even if the two heated objects T are positioned biased towards one side of the two heating electrodes 110, the electric fields generated by the two heating electrodes 110 act evenly on the two heated objects T, enabling even heating of the entire two heated objects T.

[0073] (Information related to voltage ratio adjustment)

[0074] Since the control unit 105 calculates the target ratio of voltage VU and voltage VL using any one of equations (1) to (3), it needs to determine the number (i.e., n) and height (i.e., distance H2) of the heated objects T. The control unit 105 then... Figures 6 to 11 The various methods illustrated can determine the number and height of the heated object T.

[0075] Figure 6 This is an external view of the dielectric heating device 100 involved in the first example. Figure 7 This is an external view of the dielectric heating device 100 involved in the second example. Figure 8 This is an external view of the dielectric heating device 100 involved in the third example. Figure 9 This is an external view of the dielectric heating device 100 involved in the fourth example. Figure 10 This is an external view of the dielectric heating device 100 involved in the fifth example. Figure 11This is an external view of the dielectric heating device 100 involved in the sixth example.

[0076] like Figures 6 to 11 As shown, the dielectric heating device 100 has a touch panel display 601 for inputting and outputting various information on the front surface of the heating chamber 101 and an openable and closable door 602 on the front side of the heating chamber 113. Except for the fourth example described later, the openable and closable door 602 is provided with a window 603 for visually observing the interior of the heating chamber 113 from the front.

[0077] like Figure 6 As shown, in the dielectric heating device 100 of the first example, for example, before heating the object T, the user inputs the number of objects T to be heated and the height of the objects T to be heated into the dielectric heating device 100. Figure 6 In this example, the touch panel display 601 inputs "2" as the number of heated objects T arranged in the heating chamber 113 and "8cm" as the height (distance H2) of each heated object T. Based on the input number and height of the heated objects T, the control unit 105 calculates the target ratio of voltage VU and voltage VL using any one of (Equation 1) to (Equation 3), and performs heating control according to the target ratio.

[0078] like Figure 7 As shown, in the dielectric heating device 100 of the second example, for example, before heating the object T, the user inputs the overall height of the object T, which is disposed in the heating chamber 113, into the dielectric heating device 100. Figure 7 In the example, the height (distance H4) of the two heated objects T disposed in the heating chamber 113 is entered as "16cm" from the touch panel display 601.

[0079] In Equation 3, “n*H2” corresponds to the height (distance H4) of the object T to be heated, which is disposed in the heating chamber 113. Therefore, the control unit 105 calculates the target ratio of voltage VU and voltage VL based on the input height of the object T to be heated, using Equation 3, and performs heating control according to the target ratio.

[0080] like Figure 8 As shown, in the dielectric heating device 100 of the third example, a sensor 800 for measuring the height of the object T disposed within the heating chamber 113 is provided in the heating chamber 101. Figure 8In this example, sensor 800 is an image sensor capable of capturing images of the interior of heating chamber 113. For example, when the user instructs the start of heating, control unit 105 uses sensor 800 to capture images of the interior of heating chamber 113. Control unit 105 analyzes the captured images from sensor 800 to determine the overall height of the object T disposed within heating chamber 113. Based on the determined overall height of the object T, control unit 105 can perform heating control in the same manner as in the second example.

[0081] Furthermore, sensor 800 can also be a distance sensor. As an example, sensor 800 measures the distance between the upper electrode 111 and the heated object T by irradiating the upper surface of the heated object T with measuring light from the upper electrode 111 side. The control unit 105 can determine the overall height of the heated object T by subtracting the distance measured by sensor 800 from the distance H1 between the upper electrode 111 and the lower electrode 112.

[0082] like Figure 9 As shown, in the fourth example of the dielectric heating device 100, a touch panel display 900 is provided on the front surface of the opening / closing door 602. Additionally, an image sensor capable of capturing images of the heating chamber 113 is provided in the heating chamber 101. For example, when the user instructs the start of heating, the control unit 105 captures an image of the heating chamber 113 using the image sensor, and displays an operation screen including this captured image on the touch panel display 900. This operation screen is used by the user to specify the upper end of the object T to be heated in the captured image via touch operation.

[0083] Based on the touch position detected on the screen in the touch panel display 900, the control unit 105 determines the upper position of the heated object T in the heating chamber 113 (i.e., the overall height of the heated object T). Based on the determined overall height of the heated object T, the control unit 105 can perform heating control in the same manner as in the second example.

[0084] like Figure 10 As shown, in the dielectric heating device 100 of the fifth example, an indicator section 1000 is provided on the inner wall of the heating chamber 101 surrounding the heating chamber 113. The indicator section 1000 is an indicator that indicates the level of height inside the heating chamber 113, for example, multiple marks that indicate different levels of height.

[0085] For example, before heating the object T, the user inputs the height rating of the object T to the dielectric heating device 100, using the indicator unit 1000 as a reference. Figure 10In this example, the upper end of the object T to be heated, located within the heating chamber 113, is at approximately the same height as the mark "4" among the multiple marks on the indicator section 1000. Therefore, the touch panel display 601 inputs "4", indicating the height level. The control section 105 determines the overall height of the object T to be heated based on the input height level, and can perform heating control in the same manner as in the second example.

[0086] like Figure 11 As shown, the dielectric heating device 100 of the sixth example includes a barcode reader 1100. A barcode 1101 representing information related to the heated object T is provided on the heated object T. For example, before heating the heated object T, the user reads the barcode 1101 using the barcode reader 1100. The barcode 1101 represents the height of the heated object T, and the control unit 105 can read and determine the height of the heated object T from the barcode 1101. If the barcode 1101 includes identification information of the heated object T, the control unit 105 can determine the height of the heated object T by querying a server (not shown) based on the identification information read from the barcode 1101.

[0087] Furthermore, when the user is heating multiple objects T simultaneously, the number of objects T to be heated is input from the touch panel display 900. Therefore, the control unit 105, based on the determined height of the objects T to be heated and the input number of objects T to be heated, can perform heating control in the same manner as in the first example.

[0088] In this example, instead of having the user input the number of heated objects T, the control unit 105 can determine the number of heated objects T. For example, the control unit 105 can pre-store the matching states of the matching circuits 104A and 104B when one heated object T is being heated and the matching states of the matching circuits 104A and 104B when two heated objects T are being heated simultaneously, and determine the number of heated objects T based on the matching states in the heating control.

[0089] This disclosure is not limited to the above-described embodiments, and may be replaced by structures that are substantially the same as those described in the above embodiments, structures that have the same effect, or structures that can achieve the same purpose.

[0090] (1) Alternatively, the control unit 105 may perform feedback control on the voltage ratio adjustment described above. For example, in the drive circuit 102, a first voltage detection circuit is provided between the matching circuit 104A and the amplifier 134A. The first voltage detection circuit divides the voltage between the output of the amplifier 134A and the ground (GND) through a resistor. The first voltage detection circuit rectifies and smooths the voltage divided by the resistor and outputs it to the control unit 105.

[0091] Similarly, a second voltage detection circuit is provided between the matching circuit 104B and the amplifier 134B. This second voltage detection circuit divides the voltage between the output of the amplifier 134B and ground (GND) using resistors, and then rectifies and smooths it before outputting it to the control unit 105. Furthermore, in each voltage detection circuit, the resistors used for voltage division have high resistance values ​​to the extent that they do not impart impedance effects.

[0092] The control unit 105 reads the voltage values ​​output from the first and second voltage detection circuits, respectively, and calculates the ratio (measured ratio) of these voltage values. The control unit 105 adjusts the electrode voltages applied to the upper electrode 111 and lower electrode 112 in a manner that makes the measured ratio consistent with the target ratios of voltage VL and voltage VU. Through this feedback control, voltage VU and voltage VL can be made more accurately consistent with the target ratios.

[0093] (2) The structure of the driving circuit 102 is not limited to the above-described embodiments, and various structures can be applied. Figure 12A This is a diagram showing the overall structure of the dielectric heating device 100 involved in the modified example. Figure 12B This is a diagram showing the structure of the matching circuit 104 involved in the modified example.

[0094] exist Figure 12A In the driving circuit 102 shown, the high-frequency power supply 103 is connected to a matching circuit 104. For example... Figure 12B As shown, the matching circuit 104 includes variable coils 201A and 201B, variable capacitors 202A and 202B, and a variable capacitor 203. Variable coils 201A and 202A are connected in series with amplifier 134A. Variable coils 201B and 202B are connected in series with amplifier 134B. Variable capacitor 203 is connected in parallel with the output of the high-frequency power supply 103. In this example, the current resulting from the voltage difference between voltages VU and VL flows, for example, in the ground wire connected to the heating chamber 101.

Claims

1. A dielectric heating device, characterized by, have: Two heating electrodes are positioned opposite each other, spaced apart. A heating chamber is disposed between the two heating electrodes and is a space for placing the object to be heated; A high-frequency power supply provides high-frequency power to the two heating electrodes such that the phase difference between the voltages applied to the two heating electrodes is 180°. as well as The control unit individually adjusts the voltages applied from the high-frequency power supply to the two heating electrodes. The two heating electrodes include: an upper electrode located above the heating chamber and a lower electrode located below the heating chamber. The control unit adjusts the voltage ratio between the upper electrode and the lower electrode based on the height of the object being heated, which is disposed in the heating chamber. The control unit adjusts the voltage ratio so that the lower the height of the object to be heated disposed in the heating chamber, the greater the voltage applied to the upper electrode relative to the voltage applied to the lower electrode.

2. A dielectric heating device, characterized by, have: Two heating electrodes are positioned opposite each other, spaced apart. A heating chamber is disposed between the two heating electrodes and is a space for placing the object to be heated; A high-frequency power supply provides high-frequency power to the two heating electrodes such that the phase difference between the voltages applied to the two heating electrodes is 180°. as well as The control unit individually adjusts the voltages applied from the high-frequency power supply to the two heating electrodes. The two heating electrodes include: an upper electrode located above the heating chamber and a lower electrode located below the heating chamber. The control unit adjusts the voltage ratio between the upper electrode and the lower electrode based on the height of the object being heated, which is disposed in the heating chamber. When heating an object in the heating chamber, the voltage of the upper electrode is set to VU, the voltage of the lower electrode is set to VL, the distance between the two heating electrodes is set to H1, and the height of the object being heated is set to H2. The control unit adjusts the voltage ratio in such a way that 0.25×H2 / H1≤VL / (VL+VU)≤0.75×H2 / H1.

3. A dielectric heating device characterized by, have: Two heating electrodes are positioned opposite each other, spaced apart. A heating chamber is disposed between the two heating electrodes and is a space for placing the object to be heated; A high-frequency power supply provides high-frequency power to the two heating electrodes such that the phase difference between the voltages applied to the two heating electrodes is 180°. as well as The control unit individually adjusts the voltages applied from the high-frequency power supply to the two heating electrodes. The two heating electrodes include: an upper electrode located above the heating chamber and a lower electrode located below the heating chamber. The control unit adjusts the voltage ratio between the upper electrode and the lower electrode based on the height of the object being heated, which is disposed in the heating chamber. When two identical objects are heated in overlapping layers in the heating chamber, the voltage of the upper electrode is set to VU, the voltage of the lower electrode is set to VL, the distance between the two heating electrodes is set to H1, and the height of the heated object is set to H2. The control unit adjusts the voltage ratio in such a way that 0.5×H2 / H1≤VL / (VL+VU)≤1.5×H2 / H1.

4. A dielectric heating device characterized by, have: Two heating electrodes are positioned opposite each other, spaced apart. A heating chamber is disposed between the two heating electrodes and is a space for placing the object to be heated; A high-frequency power supply provides high-frequency power to the two heating electrodes such that the phase difference between the voltages applied to the two heating electrodes is 180°. as well as The control unit individually adjusts the voltages applied from the high-frequency power supply to the two heating electrodes. The two heating electrodes include: an upper electrode located above the heating chamber and a lower electrode located below the heating chamber. The control unit adjusts the voltage ratio between the upper electrode and the lower electrode based on the height of the object being heated, which is disposed in the heating chamber. When n identical objects are stacked and heated in the heating chamber, the voltage of the upper electrode is set to VU, the voltage of the lower electrode is set to VL, the distance between the two heating electrodes is set to H1, and the height of the heated object is set to H2. The control unit adjusts the voltage ratio in such a way that 0.25×n×H2 / H1≤VL / (VL+VU)≤0.75×n×H2 / H1.

5. The dielectric heating device according to any one of claims 1 to 4, characterized in that, The high-frequency power supply includes two amplifiers, which output voltages to the two heating electrodes respectively based on the high-frequency signal from the oscillator. The control unit adjusts the voltages applied to the two heating electrodes individually by adjusting the output voltages of the two amplifiers.

6. The dielectric heating device according to claim 5, characterized in that, The high-frequency power supply includes two variable attenuators, which are used to attenuate the high-frequency signals input to the two amplifiers respectively. The control unit adjusts the output voltage of the two amplifiers individually by adjusting the attenuation of the high-frequency signal based on the two variable attenuators.

7. The dielectric heating device according to claim 5, characterized in that, The control unit adjusts the output voltage of the two amplifiers individually by adjusting the drive voltage used to operate the two amplifiers.

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