JP7425705B2 - dielectric heating device - Google Patents

Description

The present invention relates to a dielectric heating device.

2. Description of the Related Art A dielectric heating device is known that heats an object placed in a heating chamber by applying a voltage to at least one of two opposing electrodes. In such a dielectric heating device, a technique is known in which a balanced circuit with equal electric field distribution in positive and negative times is used as a load-side circuit including a counter electrode (for example, see Patent Document 1). According to this, by applying voltages with a phase difference of 180° to the two opposing electrodes, it is possible to suppress the difference in electric field strength within the object to be heated and uniformly heat the entire object to be heated.

Patent No. 2884554

In a dielectric heating device in which the positions of two opposing electrodes (for example, an upper electrode and a lower electrode) are fixed, the distance from the object to be heated to the upper electrode may be different from the distance from the object to be heated to the lower electrode. be. In this case, even if heating control is performed using the above-mentioned balance circuit, there is a risk that a difference will occur between the electric field strength that the upper electrode acts on the object to be heated and the electric field intensity that the lower electrode acts on the object. be. If such a difference in electric field strength occurs, there is a possibility that the entire object to be heated cannot be heated evenly.

One aspect of the present disclosure aims to provide a dielectric heating device that can uniformly heat the entire object to be heated.

A dielectric heating device according to one aspect of the present disclosure includes two heating electrodes that face each other with a space between them, a heating chamber that is a space provided between the two heating electrodes and in which an object to be heated can be placed, and a heating chamber that is a space in which an object to be heated can be placed. a high frequency power supply that supplies high frequency power to the two heating electrodes so that the phase difference between the voltages applied to the two heating electrodes is 180°; A control unit that individually adjusts the voltage.

1 is a diagram showing the overall configuration of a dielectric heating device. FIG. 3 is a diagram showing the configuration of a matching circuit. 3 is a graph showing changes in electrode voltage applied to an upper electrode and a lower electrode. It is a graph showing a change in inter-electrode voltage generated between an upper electrode and a lower electrode. It is a figure which shows the heating warehouse in which one to-be-heated object T is arrange|positioned. It is a figure showing a heating warehouse in which two objects to be heated T are arranged one on top of the other. It is a figure showing a heating warehouse in which four objects to be heated T are arranged one on top of the other. 7 is a graph showing changes in the electrode voltages applied to the upper electrode and the lower electrode after adjusting the voltage ratio. FIG. 2 is an external view of a dielectric heating device according to a first example. FIG. 7 is an external view of a dielectric heating device according to a second example. FIG. 7 is an external view of a dielectric heating device according to a third example. FIG. 7 is an external view of a dielectric heating device according to a fourth example. FIG. 7 is an external view of a dielectric heating device according to a fifth example. FIG. 7 is an external view of a dielectric heating device according to a sixth example. It is a figure showing the whole structure of a dielectric heating device concerning a modification. It is a figure showing the composition of the matching circuit concerning a modification.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate explanations will be omitted.

(Overview of dielectric heating device)
The dielectric heating device 100 according to this embodiment will be explained. FIG. 1 is a diagram showing the overall configuration of a dielectric heating device 100. FIG. 2 is a diagram showing the configuration of matching circuits 104A and 104B. The dielectric heating device 100 applies a high-frequency electric field to an object to be heated, such as food, to perform heat treatment, thawing treatment, etc. of the object to be heated.

As shown in FIG. 1, the dielectric heating device 100 includes a heating chamber 101, a drive circuit 102, and a control section 105. The heating chamber 101 is shaped like a metal box and has an internal space capable of accommodating objects to be heated. The internal space of the heating warehouse 101 is open to the front and can be opened and closed by an opening/closing door not shown. FIG. 1 schematically shows a heating chamber 101 viewed from the front. The upper side, the lower side, the left side, the right side, the front side of the page, and the back side of the page in FIG. do. The metal heating chamber 101 is grounded by a grounding wire 109 or the like.

Two heating electrodes 110, a heating chamber 113, and the like are provided in the internal space of the heating warehouse 101. The two heating electrodes 110 face each other with a gap between them. As an example, the two heating electrodes 110 are an upper electrode 111 and a lower electrode 112 that face each other in the vertical direction. The upper electrode 111 and the lower electrode 112 are rectangular flat plates extending in the front, rear, left and right directions, and are arranged parallel to each other. The heating chamber 113 is a space sandwiched between the two heating electrodes 110 (upper electrode 111 and lower electrode 112) in which a plurality of objects to be heated can be placed.

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 be supplied to the two heating electrodes 110. Specifically, the high frequency power source 103 supplies high frequency power to the two heating electrodes 110 such that the phase difference between the voltages applied to the two heating electrodes 110 is 180°. High frequency power supply 103 includes an oscillator 131, a phase shifter 132, variable attenuators 133A, 133B, and amplifiers 134A, 134B.

The oscillator 131 is connected to the ground line 109 described above, and emits a voltage signal having a frequency range from HF to VHF. The voltage signal emitted by the oscillator 131 is input to variable attenuators 133A and 133B connected in parallel to the oscillator 131, respectively. However, the phase of the voltage signal input to the variable attenuator 133B is converted by 180° by the phase shifter 132 connected between the variable attenuator 133B and the high frequency power supply 103. Therefore, the phase shift difference between the voltage signals input to variable attenuators 133A and 133B is 180°.

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

As shown in FIG. 2, the input side of the matching circuit 104A is connected to the amplifier 134A, and the output side is connected to the upper electrode 111. Matching circuit 104A includes variable coil 201 and variable capacitors 202 and 203. In the matching circuit 104A, a variable coil 201 and a variable capacitor 202 are connected in series with the output of the high frequency power source 103, and the variable capacitor 203 is connected in parallel with the output of the high frequency power source 103. The variable capacitor 203 is connected to the ground line 109 described above.

The matching circuit 104A matches the input impedance of the matching circuit 104A and the output impedance of the amplifier 134A by adjusting the values of the variable coil 201 and variable capacitors 202 and 203. Thereby, the impedance on the upper electrode 111 side seen from the high frequency power supply 103 (specifically, the amplifier 134A) can be kept constant, and a voltage signal can be efficiently supplied to the upper electrode 111 side.

The matching circuit 104B has an input side connected to the amplifier 134B, and an output side connected to the lower electrode 112. Matching circuit 104B has the same configuration as matching circuit 104A, and matches the input impedance of matching circuit 104B and the output impedance of amplifier 134B. Thereby, the impedance on the lower electrode 112 side seen from the high frequency power supply 103 (specifically, the amplifier 134B) can be kept constant, and a voltage signal can be efficiently supplied to the lower electrode 112 side.

In the drive circuit 102, a voltage whose impedance has been matched by matching circuits 104A and 104B is supplied to a capacitor formed by an upper electrode 111 and a lower electrode 112. As a result, a high frequency electric field is generated between the upper electrode 111 and the lower electrode 112, and the object to be heated disposed between the upper electrode 111 and the lower electrode 112 is dielectrically heated.

FIG. 3A is a graph showing changes in the electrode voltages applied to the upper electrode 111 and the lower electrode 112. In the example of FIG. 3A, the change in the voltage that the high frequency power supply 103 applies to the upper electrode 111 and the lower electrode 112 shows a sine wave whose amplitude varies from "-0.5" to "+0.5" in one cycle. . However, the voltage applied to the upper electrode 111 and the voltage applied to the lower electrode 112 differ in phase shift by 180°.

FIG. 3B is a graph showing changes in the interelectrode voltage generated between the upper electrode 111 and the lower electrode 112. The interelectrode voltage is the difference between the voltage applied to the upper electrode 111 and the voltage applied to the lower electrode 112. FIG. 3B shows a change in the voltage between the upper electrode 111 and the lower electrode 112 shown in FIG. 3A. Since the amplitude of this change in interelectrode voltage is twice the voltage applied to the upper electrode 111 and the lower electrode 112, it is a sine whose amplitude varies from "-1.0" to "+1.0" in one cycle. Showing waves.

In this manner, in the dielectric heating device 100, the high frequency power source 103 applies voltages to the two heating electrodes 110 such that the phase difference between the voltages applied to the two heating electrodes 110 is 180°. According to such a balanced circuit type heating control, compared to an unbalanced circuit type heating control in which a voltage is applied to one of the two heating electrodes 110, the maximum voltage applied to one heating electrode 110 can be suppressed. , a larger interelectrode voltage can be generated.

The control unit 105 is an electronic component that controls heating of the dielectric heating device 100, and is configured by, for example, a microcomputer or an electronic circuit. The control unit 105 individually adjusts the voltage applied to each of the two heating electrodes 110 from the high frequency power source 103.

(Voltage ratio adjusted by the control unit)
In this embodiment, as described above, the two heating electrodes 110 include the upper electrode 111 located above the heating chamber 113 and the lower electrode 112 located below the heating chamber 113. The control unit 105 adjusts the voltage ratio between the upper electrode 111 and the lower electrode 112 based on the height of the heated object placed in the heating chamber 113 (that is, the length in the vertical direction).

The voltage ratio of the upper electrode 111 and the lower electrode 112 adjusted by the control unit 105 will be described with reference to FIGS. 4A to 4C. FIG. 4A is a diagram showing a heating chamber 101 in which one object to be heated T is placed. FIG. 4B is a diagram showing a heating chamber 101 in which two objects T to be heated are placed one on top of the other. FIG. 4C is a diagram showing a heating chamber 101 in which four heated objects T are arranged one on top of the other.

In the following description, the distance between the two heating electrodes 110 (that is, the distance between the upper electrode 111 and the lower electrode 112) is defined as the distance H1. Let the height of one heated object T be a distance H2. The magnitude of the voltage of the upper electrode 111 is defined as voltage VU. The magnitude of the voltage on the lower electrode 112 is defined as voltage VL.

In the example shown in FIG. 4A, one object to be heated T is placed on the lower electrode 112 in the heating chamber 113. When heating one object to be heated T 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 satisfy the following (Equation 1). The voltage ratio of the upper electrode 111 and the lower electrode 112 is adjusted so as to satisfy the condition.
0.25*H2/H1≦VL/(VL+VU)≦0.75*H2/H1...(Math. 1)

As illustrated in FIG. 3A, the control unit 105 controls the high frequency power supplied to each heating electrode 110 so that the phase difference between the voltages applied to the two heating electrodes 110 is 180°. However, the control unit 105 changes the ratio of the voltage VU and the voltage VL so as to satisfy (Equation 1) while maintaining the interelectrode voltage illustrated in FIG. 3B.

Here, the distance H1 is a fixed value set in advance. On the other hand, the distance H2 changes depending on the object to be heated T placed in the heating chamber 113. That is, the target ratio of the voltage VL and the voltage VU changes depending on the heated object T placed in the heating chamber 113. In the heating chamber 113, a 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 an electric field reference position. Adjusting the voltage ratio using (Equation 1) is equivalent to adjusting the electric field reference position.

In (Equation 1), “0.25*H2/H1” represents the lower limit position of the allowable width H3 in which the electric field reference position can be set within the heating chamber 113. Specifically, the lower limit position of the allowable width H3 is a distance corresponding to 1/4 of the height of the heated object T (i.e., distance H2) when viewed from the vertical center C1 of one heated object T, Located at the bottom. On the other hand, "0.75*H2/H1" represents the upper limit position of the allowable width H3. Specifically, the upper limit position of the allowable width H3 is located above a distance corresponding to 1/4 of the distance H2 when viewed from the vertical center C1.

That is, the permissible width H3 of the electric field reference position based on (Equation 1) is a width in the vertical direction corresponding to 1/2 of the distance H2 centered on the vertical center C1. When the control unit 105 adjusts the ratio of voltage VU and voltage VL so as to satisfy (Equation 1), the electric field reference position falls within the allowable width H3. As a result, a substantially uniform electric field acts on both the upper part and the lower part of one object to be heated T, with the vertical center C1 as a reference. Therefore, the whole of one object to be heated T can be heated evenly without uneven heating in the upper and lower parts of one object to be heated.

In the example shown in FIG. 4B, within the heating chamber 113, two objects T to be heated are placed one above the other on the lower electrode 112. When heating such two objects T to be heated 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 satisfy the following (Equation 2). The voltage ratio of the upper electrode 111 and the lower electrode 112 is adjusted so as to satisfy the condition.
0.5*H2/H1≦VL/(VL+VU)≦1.5*H2/H1...(Math. 2)

In (Equation 2), “0.5*H2/H1” represents the lower limit position of the allowable width H3 in which the electric field reference position can be set within the heating chamber 113. Specifically, the lower limit position of the allowable width H3 is a distance corresponding to 1/2 of the height (i.e. distance H2) of the two heated objects T, as viewed from the vertical center C2 of the two heated objects T, Located at the bottom. On the other hand, "1.5*H2/H1" represents the upper limit position of the allowable width H3. Specifically, the upper limit position of the allowable width H3 is located above by a distance corresponding to 1/2 of the distance H2 when viewed from the vertical center C2.

That is, the permissible width H3 of the electric field reference position based on (Equation 2) is a width in the vertical direction corresponding to the distance H2 centered on the vertical center C2. When the control unit 105 adjusts the ratio of voltage VU and voltage VL so as to satisfy (Equation 2), the electric field reference position falls within the allowable width H3. As a result, a substantially uniform 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, the two objects T can be evenly heated as a whole without uneven heating of the upper object T and the lower object T.

The above-mentioned (Equation 1) and (Equation 2) differ in the number of objects to be heated T, respectively. In other words, as shown in (Equation 1) and (Equation 2), when the quantity of objects to be heated T is different, 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 are set. The constant changes depending on the number of objects T to be heated. For example, in (Math. 1), the constant of the formula representing the lower limit position of the allowable width H3 is "0.25", but in (Math. 2), the constant of the formula representing the lower limit position of the allowable width H3 is "0.5". becomes.

Therefore, in (Equation 1) and (Equation 2), by setting the number of objects to be heated T as a variable called n pieces, (Equation 1) and (Equation 2) can be converted into the common equation (Equation 3). I can derive it. That is, when heating the same n objects T to be heated T stacked up and down in n stages 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, and performs the following operations. The voltage ratio of the upper electrode 111 and the lower electrode 112 is adjusted so as to satisfy (Equation 3).
0.25*n*H2/H1≦VL/(VL+VU)≦0.75*n*H2/H1
...(Math 3)
Note that (Math. 3) becomes the same formula as (Math. 1) by substituting "n=1", and becomes the same formula as (Math. 2) by substituting "n=2".

In (Equation 3), “0.25*n*H2/H1” represents the lower limit position of the allowable width H3 in which the electric field reference position can be set within the heating chamber 113. Specifically, the lower limit position of the allowable width H3 is determined by adding "0.25*n" to the height of the heated objects T (i.e., the distance H2) when viewed from the vertical center C3 of the n heated objects T. It is located downward by the multiplied distance. On the other hand, "0.75*n*H2/H1" represents the upper limit position of the allowable width H3. Specifically, the upper limit position of the allowable width H3 is located above the distance H2 multiplied by "0.25*n" when viewed from the vertical center C3.

In the example shown in FIG. 4C, in the heating chamber 113, four objects T to be heated are arranged one above the other on the lower electrode 112, so "n=4". In this case, the lower limit position of the allowable width H3 is located below by a distance corresponding to the distance H2 when viewed from the vertical center C3 of the four objects T to be heated. The upper limit position of the allowable width H3 is located above the distance corresponding to the distance H2 when viewed from the vertical center C3.

In other words, the allowable width H3 of the electric field reference position based on (Equation 3) is a width in the vertical direction corresponding to "2*0.25*n" centered on the vertical center C3. When the control unit 105 adjusts the ratio of the voltage VU and the voltage VL so as to satisfy (Equation 3), the electric field reference position falls within the allowable width H3, so the entire n heated objects T are uniformly distributed as described above. It can be heated to

In this embodiment, the control unit 105 adjusts the ratio of the voltage VU and the voltage VL so that the electric field reference position substantially coincides with the vertical center of the allowable width H3, regardless of the number n. As a result, a more uniform electric field acts on both the portion above the vertical center C3 and the portion below the vertical center C3 of the n heated objects T. . Therefore, the entire n objects to be heated T can be heated more evenly. Of course, the electric field reference position may be shifted from the vertical center of the allowable width H3 as long as it falls within the allowable width H3.

(How to adjust voltage ratio)
For example, when controlling the heating of the dielectric heating device 100, the control unit 105 calculates the target ratio of the voltage VU and the voltage VL using one of the above-mentioned equations (1) to (3). Control unit 105 adjusts the electrode voltages applied to upper electrode 111 and lower electrode 112 so that voltage VU and voltage VL match the target ratio.

In this embodiment, as described above, the high frequency power supply 103 includes two amplifiers 134A and 134B that output voltages to the two heating electrodes 110, respectively, according to the high frequency signal from the oscillator 131. The control unit 105 individually adjusts the voltage applied to each of the two heating electrodes 110 by individually adjusting the output voltages of the two amplifiers 134A and 134B. A specific aspect of such a voltage ratio adjustment method will be described with reference to FIG.

A first aspect of the voltage ratio adjustment method will be explained. As mentioned above, the high frequency power supply 103 includes two variable attenuators 133A and 133B for attenuating the high frequency signals input to the two amplifiers 134A and 134B, respectively. The control unit 105 individually adjusts the output voltages of the two amplifiers 134A and 134B by individually adjusting the amount of attenuation of the high frequency signal by the two variable attenuators 133A and 133B.

For example, the control unit 105 increases the attenuation amount of one of the variable attenuators 133A and 133B, and decreases the attenuation amount of the other so that the voltage VU and the voltage VL reach the target ratio. As a result, one of the output voltages of the two amplifiers 134A and 134B increases, while the output voltage of the other decreases. Thereby, the electrode voltages applied to the upper electrode 111 and the lower electrode 112 substantially match the target ratio of voltage VU and voltage VL.

A second aspect of the voltage ratio adjustment method will be explained. In the two amplifiers 134A and 134B, the amplification factor of the input high frequency signal changes depending on the magnitude of the drive voltage supplied to each by the control unit 105. Therefore, the control unit 105 individually adjusts the output voltages of the two amplifiers 134A and 134B by individually adjusting the drive voltages for operating the two amplifiers 134A and 134B.

For example, the control unit 105 increases one drive voltage and decreases the other drive voltage among the drive voltages input to the amplifiers 134A and 134B so that the voltage VU and the voltage VL have a target ratio. As a result, one of the output voltages of the two amplifiers 134A and 134B increases, while the output voltage of the other decreases. Thereby, the electrode voltages applied to the upper electrode 111 and the lower electrode 112 substantially match the target ratio of voltage VU and voltage VL.

According to the first and second aspects described above, voltage VU can be adjusted without impairing impedance matching between amplifier 134A and upper electrode 111 and without impairing impedance matching between amplifier 134B and lower electrode 112. and voltage VL can be adjusted to match the target ratio.

Here, with reference to FIG. 5, changes in the electrode voltages applied to the upper electrode 111 and the lower electrode 112 after the voltage ratio adjustment described above will be described. FIG. 5 is a graph showing changes in the electrode voltages applied to the upper electrode 111 and the lower electrode 112 after adjusting the voltage ratio. For example, in FIG. 4B, the lower electrode 112 of the two heated objects T placed in the heating chamber 113 is closer than the upper electrode 111. Therefore, the electric field generated from the upper electrode 111 is less likely to act on the two heated objects T than the electric field generated from the lower electrode 112.

In such a case, the control unit 105 calculates a target ratio such that the voltage VU becomes larger than the voltage VL based on (Equation 2). For example, assume that the control unit 105 calculates "0.7:0.3" as the target ratio of voltage VU and voltage VL. In this case, electrode voltages as illustrated in FIG. 5 are applied to the upper electrode 111 and the lower electrode 112.

In the example of FIG. 5, similarly to the example of FIG. 3A, the voltage applied to the upper electrode 111 (ie, voltage VU) and the voltage applied to the lower electrode 112 (ie, voltage VL) have a phase shift of 180° different from each other. However, the voltage VU shows a sine wave whose amplitude varies from "-0.7" to "+0.7" in one cycle. The voltage VL shows a sine wave that varies in amplitude from "-0.3" to "+0.3" in one cycle. In this case as well, the change in interelectrode voltage that occurs between the upper electrode 111 and the lower electrode 112 varies with an amplitude of "-1.0" to "+1.0" in one cycle, as in FIG. 3B. shows a sine wave.

As a result, the electric field generated from the upper electrode 111 becomes larger than the electric field generated from the lower electrode 112. Further, the electric field generated from the upper electrode 111 acts on the two objects to be heated T with the same intensity as the electric field generated from the lower electrode 112. Therefore, even if the two heated objects T are arranged biased to one side of the two heating electrodes 110, the electric field generated by the two heating electrodes 110 can be applied equally to the two heated objects T, and the The entire object T to be heated can be heated evenly.

(Obtaining information regarding voltage ratio adjustment)
In order to calculate the target ratio of the voltage VU and the voltage VL using one of (Equation 1) to (Equation 3), the control unit 105 has the number (i.e., n) of objects to be heated T and the height (i.e., the distance H2). ) needs to be identified. The control unit 105 can specify the number and height of the objects to be heated T according to various embodiments illustrated in FIGS. 6 to 11.

FIG. 6 is an external view of the dielectric heating device 100 according to the first example. FIG. 7 is an external view of a dielectric heating device 100 according to a second example. FIG. 8 is an external view of a dielectric heating device 100 according to a third example. FIG. 9 is an external view of a dielectric heating device 100 according to a fourth example. FIG. 10 is an external view of a dielectric heating device 100 according to a fifth example. FIG. 11 is an external view of a dielectric heating device 100 according to the sixth example.

As shown in FIGS. 6 to 11, the dielectric heating device 100 has a touch panel display 601 on the front side of the heating chamber 101 for inputting and outputting various information, and an opening/closing door 602 that can be opened and closed on the front side of the heating chamber 113. It is provided. The opening/closing door 602 is provided with a window 603 for visually observing the inside of the heating chamber 113 from the front, except for the fourth example described below.

As shown in FIG. 6, in the dielectric heating device 100 of the first example, for example, before heating the objects T, the user determines the number of objects T and the height of one object T during dielectric heating. input to the device 100. In the example of FIG. 6, "2" which is the number of heated objects T placed in the heating chamber 113 and "8 cm" which is the height (distance H2) of each heated object T are displayed on the touch panel display. It is input from 601. The control unit 105 calculates a target ratio of the voltage VU and the voltage VL based on the input number and height of the objects to be heated T using any one of (Equation 1) to (Equation 3), and performs heating according to the target ratio. All you have to do is execute the control.

As shown in FIG. 7, in the dielectric heating device 100 of the second example, for example, before heating the object T, the user adjusts the height of the entire object T placed in the heating chamber 113 using the dielectric heating device. Enter 100. In the example of FIG. 7, “16 cm”, which is the height (distance H4) of the two heated objects T placed in the heating chamber 113, is input from the touch panel display 601.

“n*H2” in (Equation 3) corresponds to the height (distance H4) of the entire heated object T placed in the heating chamber 113. Therefore, the control unit 105 calculates the target ratio of the voltage VU and the voltage VL based on the input height of the entire object to be heated T using (Equation 3), and executes the heating control according to the target ratio.

As shown in FIG. 8, in the third example of the dielectric heating device 100, a sensor 800 for measuring the height of the entire heated object T placed in the heating chamber 113 is provided in the heating chamber 101. . In the example of FIG. 8, the sensor 800 is an image sensor capable of photographing the inside of the heating chamber 113. For example, when the user instructs to start heating, the control unit 105 photographs the inside of the heating chamber 113 using the sensor 800. The control unit 105 analyzes the captured image of the sensor 800 and specifies the overall height of the heated object T placed in the heating chamber 113. The control unit 105 can perform heating control similarly to the second example based on the specified height of the entire object to be heated T.

Note that the sensor 800 may be a distance measuring sensor. As an example, the sensor 800 measures the distance between the upper electrode 111 and the object to be heated T by irradiating measurement light onto the upper surface of the object to be heated T from the upper electrode 111 side. The control unit 105 can specify the entire height of the heated object T by subtracting the distance measured by the sensor 800 from the distance H1 between the upper electrode 111 and the lower electrode 112.

As shown in FIG. 9, 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. Further, an image sensor capable of photographing the inside of the heating chamber 113 is provided in the heating warehouse 101. For example, when the user instructs to start heating, the control unit 105 photographs the inside of the heating chamber 113 using an image sensor, and displays an operation screen including the photographed image on the touch panel display 900. This operation screen is a screen for allowing the user to specify the upper end of the object to be heated T in the photographed image by a touch operation.

The control unit 105 specifies the upper end position of the object to be heated T in the heating chamber 113 (that is, the height of the entire object to be heated T) based on the touch position on the screen detected by the touch panel display 900. The control unit 105 can perform heating control similarly to the second example based on the specified height of the entire object to be heated T.

As shown in FIG. 10, in the dielectric heating device 100 of the fifth example, an indicator portion 1000 is provided on the inner wall of the heating chamber 101 surrounding the heating chamber 113. The indicator portion 1000 is an indicator indicating the height level within the heating chamber 113, and is, for example, a plurality of markers indicating mutually different height levels.

For example, before heating the object to be heated T, the user inputs the height level of the object to be heated T into the dielectric heating device 100 with reference to the index section 1000. In the example of FIG. 10, the upper end of the object to be heated T placed in the heating chamber 113 is at approximately the same height as the marker at level "4" among the plurality of markers of the index section 1000. Therefore, "4" indicating the height level is input from the touch panel display 601. The control unit 105 can perform heating control similarly to the second example by specifying the height of the entire heated object T based on the input height level.

As shown in FIG. 11, the dielectric heating device 100 of the sixth example includes a barcode reader 1100. The object to be heated T is provided with a barcode 1101 indicating information regarding the object to be heated T. For example, before heating the object to be heated T, the user reads the barcode 1101 with the barcode reader 1100. The barcode 1101 indicates the height of the object to be heated T. The control unit 105 may read and specify the height of the object to be heated T from the barcode 1101. When the barcode 1101 includes identification information of the heated object T, the control unit 105 queries a server (not shown) to determine the height of the heated object T based on the identification information read from the barcode 1101. Bye.

Further, when heating a plurality of objects T at the same time, the user inputs the number of objects T to be heated from the touch panel display 900. Thereby, the control unit 105 can perform heating control in the same way as in the first example, based on the specified height of the heated object T and the inputted number of heated objects T.

In this example, instead of the user inputting the number of objects T to be heated, the control unit 105 may specify the number of objects T to be heated. For example, the control unit 105 controls, for the same object T, the matching state of the matching circuits 104A, 104B when heating one object T, and the matching state of the matching circuits 104A, 104B when heating two objects T simultaneously. By storing in advance the matching state of , the quantity of the objects to be heated T may be specified based on the matching state during heating control.

The present disclosure is not limited to the above-described embodiments, and is replaced with a structure that is substantially the same as the structure shown in the above-described embodiment, a structure that has the same effect, or a structure that can achieve the same purpose. It's okay.

(1) The control unit 105 may perform feedback control of 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) using resistors. The first voltage detection circuit outputs the voltage divided by the resistors to the control unit 105 after rectifying and smoothing the voltage.

Similarly, a second voltage detection circuit is provided between matching circuit 104B and amplifier 134B. The second voltage detection circuit divides the voltage between the output of the amplifier 134B and the ground (GND) using resistors, rectifies and smoothes the voltage, and outputs the divided voltage to the control unit 105. Note that in each voltage detection circuit, the resistance used for voltage division is set to have a high resistance value that does not affect impedance.

The control unit 105 reads the voltage values output from the first and second voltage detection circuits, respectively, and calculates the ratio (actually measured ratio) of these voltage values. Control unit 105 may adjust the electrode voltages applied to upper electrode 111 and lower electrode 112 so that this measured ratio matches the target ratio of voltage VL and voltage VU. Such feedback control allows voltage VU and voltage VL to more accurately match the target ratio.

(2) The configuration of the drive circuit 102 is not limited to the above embodiment, and various configurations can be applied. FIG. 12A is a diagram showing the overall configuration of a dielectric heating device 100 according to a modification. FIG. 12B is a diagram showing a configuration of matching circuit 104 according to a modified example.

In the drive circuit 102 shown in FIG. 12A, the high frequency power supply 103 is connected to one matching circuit 104. As shown in FIG. 12B, matching circuit 104 includes variable coils 201A, 201B, variable capacitors 202A, 202B, and variable capacitor 203. Variable coil 201A and variable capacitor 202A are connected in series with amplifier 134A. Variable coil 201B and variable capacitor 202B are connected in series with amplifier 134B. Variable capacitor 203 is connected in parallel with the output of high frequency power supply 103. In this example, a current corresponding to the voltage difference between the voltage VU and the voltage VL flows through a grounding wire connected to the heating chamber 101, for example.

100 dielectric heating device, 103 high frequency power supply, 105 control unit, 110 heating electrode, 111 upper electrode, 112 lower electrode, 113 heating chamber, 131 oscillator, 133A, 133B variable attenuator, 134A, 134B amplifier

Claims (7)

two heating electrodes facing each other with a space between them;
a heating chamber that is provided between the two heating electrodes and is a space in which an object to be heated can be placed;
a high frequency power source that supplies high frequency power to the two heating electrodes so that the phase difference between the voltages applied to the two heating electrodes is 180°;
a control unit that individually adjusts the voltage applied to each of the two heating electrodes from the high frequency power source;
Equipped with
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 of the upper electrode and the lower electrode based on the height of the object to be heated arranged in the heating chamber,
The control unit is configured such that the voltage applied to the upper electrode becomes larger with respect to the voltage applied to the lower electrode as the height of the object to be heated disposed in the heating chamber is lower. , a dielectric heating device that adjusts the voltage ratio. two heating electrodes facing each other with a space between them;
a heating chamber that is provided between the two heating electrodes and is a space in which an object to be heated can be placed;
a high frequency power source that supplies high frequency power to the two heating electrodes so that the phase difference between the voltages applied to the two heating electrodes is 180°;
a control unit that individually adjusts the voltage applied to each of the two heating electrodes from the high frequency power source;
Equipped with
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 of the upper electrode and the lower electrode based on the height of the object to be heated arranged in the heating chamber,
When heating one object to be heated in the heating chamber, the control section sets a voltage of the upper electrode to VU, a voltage of the lower electrode to VL, a distance between the two heating electrodes to H1, and a voltage of the upper electrode to VL. Assuming the height of the heated object as H2,
0.25*H2/H1≦VL/(VL+VU)≦0.75*H2/H1
adjusting the voltage ratio so as to satisfy
Dielectric heating device. two heating electrodes facing each other with a space between them;
a heating chamber that is provided between the two heating electrodes and is a space in which an object to be heated can be placed;
a high frequency power source that supplies high frequency power to the two heating electrodes so that the phase difference between the voltages applied to the two heating electrodes is 180°;
a control unit that individually adjusts the voltage applied to each of the two heating electrodes from the high frequency power source;
Equipped with
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 of the upper electrode and the lower electrode based on the height of the object to be heated arranged in the heating chamber,
When heating the same two objects to be heated by stacking them in upper and lower layers in the heating chamber, the control section sets a voltage of the upper electrode to VU, a voltage of the lower electrode to VL, and a voltage between the two heating electrodes. Assuming that the distance is H1 and the height of the heated object is H2,
0.5*H2/H1≦VL/(VL+VU)≦1.5*H2/H1
adjusting the voltage ratio so as to satisfy
Dielectric heating device. two heating electrodes facing each other with a space between them;
a heating chamber that is provided between the two heating electrodes and is a space in which an object to be heated can be placed;
a high frequency power source that supplies high frequency power to the two heating electrodes so that the phase difference between the voltages applied to the two heating electrodes is 180°;
a control unit that individually adjusts the voltage applied to each of the two heating electrodes from the high frequency power source;
Equipped with
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 of the upper electrode and the lower electrode based on the height of the object to be heated arranged in the heating chamber,
When heating the same n objects to be heated by stacking them up and down in n stages in the heating chamber, the control unit sets the voltage of the upper electrode to VU, the voltage of the lower electrode to VL, and sets the voltage of the two heating electrodes to VU. The distance between them is H1, and the height of the heated object is H2,
0.25*n*H2/H1≦VL/(VL+VU)≦0.75*n*H2/H1
adjusting the voltage ratio so as to satisfy
Dielectric heating device. The high frequency power source includes two amplifiers that output the voltage to the two heating electrodes, respectively, in response to a high frequency signal from an oscillator,
The control unit individually adjusts the voltage applied to each of the two heating electrodes by individually adjusting the output voltages of the two amplifiers.
A dielectric heating device according to any one of claims 1 to 4. The high frequency power supply includes two variable attenuators for respectively attenuating the high frequency signals input to the two amplifiers,
The control unit individually adjusts the output voltages of the two amplifiers by individually adjusting the amount of attenuation of the high frequency signal by the two variable attenuators.
The dielectric heating device according to claim 5. The control unit individually adjusts the output voltages of the two amplifiers by individually adjusting drive voltages for operating the two amplifiers.
The dielectric heating device according to claim 5.

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