Microwave processing device

Abstract

The present disclosure relates to a microwave treatment device, the purpose of the present disclosure being to perform a thawing process with excellent efficiency using HF- or UHF-band electromagnetic waves without increasing the size of peripheral equipment of the device. This microwave treatment device comprises: a heating chamber that accommodates an object being heated; a carrier signal generator that generates microwave-band carrier signals; a modulation signal generator that generates HF- or UHF-band modulation signals; a modulation unit to which the carrier signals and modulation signals are inputted, the modulation unit carrying out amplitude modulation of the carrier signals using the modulation signals; a first antenna that radiates output signals outputted from the modulation unit into the heating chamber; and a re-radiation device that receives the output signals, extracts the frequency component of the modulation signal from the received output signals, and re-radiates the output signals into the heating chamber.

Description

[Technical Field]

[0001] The present invention relates to a microwave processing apparatus. [Background technology]

[0002] A microwave oven, a type of microwave processing device, is known for its ability to heat and cook food uniformly using microwaves. However, thawing food using a microwave oven can cause uneven thawing and undercooked food edges due to the different loss coefficients of water and ice.

[0003] Patent Document 1 discloses a method for solving this problem by simultaneously using microwaves and high frequencies. The difference in loss coefficient between water and ice is less pronounced at lower frequency bands than at microwaves in the 2400 MHz band. Therefore, the microwave processing device in Patent Document 1 is equipped with microwave and high frequency (HF) band oscillation sources. By irradiating HF band radio waves during the thawing process, efficient thawing is achieved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-143868 Summary of the Invention [Problem to be solved by the invention]

[0005] However, to efficiently defrost using HF electromagnetic waves, it is necessary to use multiple antennas to irradiate the object to be heated, which poses the problem of increasing the size of the peripheral equipment.

[0006] To solve the above-mentioned problems, the present disclosure uses a re-radiation device that extracts and re-radiates only the frequency component of a modulated signal from a carrier signal that has been amplitude-modulated using a modulated signal in the HF or ultra-high frequency (UHF) band, which has a frequency lower than the microwave band.As a result, an object of the present disclosure is to provide a microwave processing device that can perform efficient thawing processing using electromagnetic waves in the HF or UHF band without increasing the size of the peripheral equipment of the device. [Means for solving the problem]

[0007] An embodiment of the present disclosure is preferably a microwave processing device comprising: a heating chamber that accommodates an object to be heated; a carrier signal generator that generates a carrier signal in the microwave band; a modulating signal generator that generates a modulating signal in the HF or UHF band; a modulating unit that receives the carrier signal and the modulating signal and amplitude-modulates the carrier signal using the modulating signal; a first antenna that radiates the output signal output from the modulating unit into the heating chamber; and a re-radiating unit that receives the output signal, extracts the frequency component of the modulating signal from the received output signal, and re-radiates it into the heating chamber. [Effects of the Invention]

[0008] According to an aspect of the present disclosure, it is possible to provide a microwave processing device that can perform an efficient thawing process using electromagnetic waves in the HF or UHF band without increasing the size of peripheral equipment of the device. [Brief explanation of the drawings]

[0009]

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[0010] Embodiment 1 [Conventional configuration] Prior to describing the first embodiment, a configuration of a conventional example will be described as background. As a method of preserving food, freezing fresh foods such as meat and seafood, and cooked foods, is widely used. In particular, in recent years, improvements in freezing technology have made it possible to preserve food for long periods while maintaining its freshness. Accordingly, there has been an increasing demand for thawing devices that can perform thawing without reducing the freshness of food. A so-called microwave oven is known as such a thawing device.

[0011] FIG. 1 is a diagram showing the configuration of a conventional microwave oven. A microwave oven is generally a microwave processing device that uses microwaves of 2450 MHz and can perform thawing cooking and heating cooking. The conventional microwave oven includes an oscillator 10A. The oscillator 10A is a high-power direct oscillation device using a magnetron, which is a type of vacuum tube. The oscillator 10A generates an electromagnetic wave 30A with the magnetron according to the control signal of the control unit 7. The electromagnetic wave 30A is radiated into the heating chamber 5 through the antenna 4A. In the heating chamber 5, the object to be heated 8 is placed on the mounting table 9 and heated by the electromagnetic wave 30A.

[0012] As microwaves for high-frequency heating, the ISM (Industrial, Scientific and Medical) band is used. The oscillation frequency of the magnetron is set to a predetermined value included in the range from, for example, 2400 MHz to 2500 MHz. By using microwaves, for heating cooking, generally uniform processing can be performed on the food to be cooked.

[0013] However, for thawing cooking, in some cases, uniform processing cannot be performed by simple microwave irradiation. As a cause, it can be cited that the loss factor, which is an index of energy absorption efficiency, is greatly different between water and ice. For example, for microwaves of 2450 MHz, the energy absorbed by water is more than 1000 times that of ice. Therefore, a large difference in the absorbed energy occurs between the peripheral part of the food to be thawed that melts at the initial stage of thawing and the central part that does not melt. As a result, phenomena such as thawing unevenness where the heating condition is non-uniform between the peripheral part and the central part of the food to be cooked, and overheating of only the peripheral part such as boiling, which cause quality deterioration, occur.

[0014] In order to solve the above problems, Patent Document 1 discloses a cooking heater that efficiently performs thawing processing using electromagnetic waves in the high-frequency (HF) band. It is known that the difference in the loss factor between water and ice is relatively smaller in the lower-frequency HF band than in microwaves with a higher frequency. Therefore, in Patent Document 1, by using electromagnetic waves in the HF band such as 13560 kHz during the thawing process, the thawing process is performed more efficiently than with microwaves.

[0015] Fig. 2 is a diagram showing the configuration of a conventional cooking device that uses HF-band electromagnetic waves. Using Fig. 2, the configuration of the cooking device disclosed in Patent Document 1 that controls microwaves and HF-band electromagnetic waves according to the state of the object to be heated will be described.

[0016] First, we will discuss cooking other than thawing. The cooking appliance is equipped with an oscillator 10A. Oscillator 10A generates electromagnetic waves 30A using a magnetron in accordance with a control signal from control unit 7. Electromagnetic waves 30A are radiated into heating chamber 5 via antenna 4A. Inside heating chamber 5, an object to be heated 8 is placed on a table 9 and is heated by electromagnetic waves 30A. This is similar to the conventional microwave oven shown in FIG.

[0017] Next, the thawing process will be described. The cooking device is equipped with oscillator 11A, which is different from oscillator 10A. Oscillator 11A is an oscillation source having one of the frequencies of 13,560 kHz, 27,120 kHz, or 40.68 MHz, which are in the HF band of the ISM band. Oscillator 11A generates electromagnetic waves 30B using a magnetron in accordance with a control signal from control unit 7. Electromagnetic waves 30B are radiated into heating chamber 5 via antenna 4B, thawing object 8 to be heated.

[0018] As described above, the cooking device in Fig. 2 uses conventional microwaves for cooking other than thawing, and uses HF electromagnetic waves for thawing. In this way, Patent Document 1 provides a cooking device that can perform thawing efficiently.

[0019] [Issues with conventional examples] Next, the problems with the conventional example will be explained. One of the problems with the conventional example is that in order to improve the efficiency of the thawing process using electromagnetic waves in the HF band, it is unavoidable to increase the size of the device.

[0020] When using a household microwave oven, standing waves are generated inside its housing. Among the irradiated microwaves, some are absorbed by the object to be heated, and the rest are reflected inside the housing. This is because the reflected wave is combined with the incident wave. Since the internal dimension of the housing is between 30 cm and 40 cm, in the case of microwaves with a wavelength of 12.5 cm in vacuum and a frequency of 2400 MHz, these standing waves can exist inside the housing.

[0021] However, in the case of microwaves with a wavelength of 2300 cm in vacuum and a frequency of 13560 kHz, standing waves do not form inside the housing, and the environment inside the housing becomes a near-field. In the near-field, the larger the antenna area or the more antennas are installed, the higher the radiation efficiency.

[0022] FIG. 3 and FIG. 4 are diagrams showing the configuration of a conventional microwave processing apparatus related to solving the problem. As described above, in order to perform thawing processing efficiently with electromagnetic waves of 13560 kHz, it is necessary to irradiate the object to be heated from a plurality of antennas. For example, a method of installing a plurality of sets of an oscillator 11A and an antenna 4B as shown in FIG. 3, or a method of distributing the oscillation output of the oscillator 11A and supplying power to a plurality of antennas 4B as shown in FIG. 4 can be considered. However, all of these methods lead to the problem of increasing the size of the peripheral equipment of the heating chamber 5. The present disclosure provides a microwave processing apparatus that solves this problem.

[0023] [Configuration of Embodiment 1] FIG. 5 is a diagram showing the configuration of a microwave processing apparatus according to Embodiment 1 of the present disclosure. The microwave processing apparatus according to Embodiment 1 includes a carrier wave signal generator 10. The carrier wave signal generator 10 generates a carrier wave signal 40 and outputs it to the modulation unit 2. The frequency of the carrier wave signal 40 is preferably either 2450 MHz or 5800 MHz in the ISM band.

[0024] The microwave processing apparatus also includes a modulation signal generator 11. The modulation signal generator 11 generates a modulation signal 42 and outputs it to the modulation unit 2. The frequency of the modulation signal 42 is set to be sufficiently lower than the frequency of the carrier signal 40. The HF band of 13.56 MHz or the UHF band of 860 - 960 MHz, for which international compatibility is ensured in the wireless communication standard, is preferable, and it may be any one of 27120 kHz, 40.68 MHz, or 100 ± 10 MHz.

[0025] The modulation unit 2 amplitude-modulates the input carrier signal 40 using the input modulation signal 42. The modulation unit 2 can be realized, for example, by a method using a non-linear element that applies a signal to a non-linear element by connecting a modulation signal amplifier and a carrier oscillator output in series, or by switching modulation. Then, the amplitude-modulated carrier signal 44 is input to the solid-state power amplifier 3.

[0026] The solid-state power amplifier 3 amplifies the carrier signal 44 and outputs the amplified carrier signal 46 to the antenna 4. The solid-state power amplifier 3 is composed of a dielectric substrate made of a low dielectric loss material, and a circuit is formed by a conductor pattern formed on one side thereof. Also, in order to operate the semiconductor element, which is an amplification element, properly, matching circuits are arranged on the input side and the output side of each semiconductor element, respectively. The semiconductor element can be realized, for example, by a MOSFET such as a HEMT (High Electron Mobility Transistor), a Lateral Diffusion Metal-oxide Semiconductor Field-Effect Transistor (LDMOSFET), or a bipolar junction transistor (BJT). Note that the semiconductor element is not limited to a specific type.

[0027] The antenna 4 radiates the carrier signal 46 into the heating chamber 5. The re-radiation device 6 receives the radiated carrier signal 48, extracts the frequency component of the modulation signal, and re-radiates the modulation signal 50 to the heating chamber 5. The operation of the re-radiation device 6 will be described later.

[0028] The control unit 7 is connected to the carrier wave signal generator 10, the modulation signal generator 11, and the modulation unit 2. Then, by changing the on and off of the signal, the frequency of the generated signal, the output of the signal, etc., the operations of the carrier wave signal generator 10 and the modulation signal generator 11 are controlled. Further, the control unit 7 controls the operation of the modulation unit 2 to realize the change of the modulation index M and the burst operation described later.

[0029] The microwave transmission line connecting each functional block forms a transmission circuit with a characteristic impedance of 50 Ω by a conductor pattern provided on one side of the dielectric substrate.

[0030] FIG. 6 is a diagram showing the configuration of the re-radiation device according to the first embodiment. The re-radiation device 6 extracts the frequency components of the modulation signal using RFID (Radio Frequency Identification) technology. The re-radiation device 6 includes an antenna 21 that receives electromagnetic waves in the microwave band. The antenna 21 receives the microwave band carrier wave signal 48 radiated from the antenna 4 into the heating chamber 5 and outputs it to the rectifier 23.

[0031] The rectifier 23 outputs the input carrier wave signal 48 to the smoothing circuit 24 and the low-pass filter (LPF) 25. The rectifier 23 can be realized by, for example, a half-wave rectifier or a full-wave rectifier using a diode.

[0032] The smoothing circuit 24 smooths the input carrier wave signal to extract the DC component and supplies it as the power supply power to the amplifier 26. The LPF 25 extracts the frequency components of the modulation signal from the input carrier wave signal and supplies it to the amplifier 26. The amplifier 26 amplifies the frequency components of the modulation signal extracted by the LPF 25. Then, via the antenna 22, the amplified modulation signal 50 is re-radiated into the heating chamber 5.

[0033] FIG. 7 is a diagram showing a modification of the re-radiation device according to the first embodiment. The re-radiation device 6a includes an envelope detection circuit composed of a rectifier 23 and a smoothing circuit 27. By this circuit, similar to the re-radiation device 6, the modulation signal 50 is re-radiated into the heating chamber 5.

[0034] [Operation of Embodiment 1] Next, the operation will be described. The frequency of the carrier signal in Embodiment 1 is in the 2400 MHz band of the microwave band, hereinafter represented as fc. This is the same as the frequency used in a general microwave heating device in Japan, so-called a microwave oven. Also, the frequency of the modulation signal according to Embodiment 1 is 13.56 MHz in the HF band, hereinafter represented as fm.

[0035] During cooking, only the carrier signal is operated in the same manner as a conventional microwave oven, so amplitude modulation using the modulation signal is not performed. On the other hand, during thawing, a signal amplitude-modulated by the modulation signal is irradiated. In this case, the signal s(t) output from the modulation unit 2 can be expressed by the following equation.

[0036] [Equation]

[0037] In Equation 1, A is the amplitude constant, M is the modulation index, and t is time. The modulation index M satisfies 0 ≦ M ≦ 1. When M = 0, s(t) becomes a sine wave without modulation.

[0038] When M > 0, the amplitude of s(t) fluctuates, and its frequency spectrum has three peaks. FIG. 8 is a graph showing the waveform of the signal s(t) when the modulation index M = 1. At this time, the amplitude component of the amplitude-modulated signal wave fluctuates as shown in the figure. Also, FIG. 9 is a graph showing the frequency spectrum of the signal s(t) when the modulation index M is changed. Here, the waveforms when the modulation index M is changed to 0.1 and 0.5 are shown, and it can be seen that the magnitude of the waveform fluctuation changes depending on the value of the modulation index M. The frequency of the main peak is fc of the carrier frequency, and the sidebands, which are the peaks at both ends thereof, are generated at positions equally separated around fc such as fc ± fm. In this way, the amplitude component of fc does not change, and only the amplitude of the sidebands has the characteristic of becoming M / 2. The average power of this carrier wave is A 2 / 2.

[0039] By changing the modulation index M, the HF band power can be adjusted to be more effective for defrosting. This change corresponds to changing the output power of fm. For example, by using M=1, which is the maximum output, in the early stages of defrosting, and M=0.5 in the later stages of defrosting, uniform defrosting can be achieved.

[0040] The carrier signal 48 radiated from the antenna 4 contains three 2400 MHz band signals, fc-fm, fc, and fm+fc, which are formed by a 2400 MHz band carrier frequency fc and an HF or UHF band modulating signal fm. These signals are radiated onto the object 8 to be heated and are also input to the re-radiation device 6 installed in the heating chamber 5. In the re-radiation device 6, using the configuration shown in Figure 6, a modulating signal 50, which is the HF or UHF band signal fm, is re-radiated from the antenna 22. This is also radiated onto the object 8 to be heated.

[0041] Because the power of the re-radiation device 6 is supplied by smoothing the input microwave band, there is no need for a power distribution device and the associated wiring, or for an oscillator dedicated to the HF or UHF band. Therefore, by simply adding re-radiation equipment using RFID technology, it is possible to irradiate the object 8 with an HF or UHF band signal suitable for thawing, without increasing the size of the peripheral equipment outside the heating chamber 5. By installing multiple units of this re-radiation equipment inside the heating chamber 5, it is possible to irradiate the object 8 with an HF or UHF band signal from various directions. As a result, thawing can be achieved efficiently while suppressing the increase in size of the peripheral equipment.

[0042] The carrier signal may be a burst signal instead of a continuous wave as shown in FIG. 8 . Conventionally, microwave heating devices without an HF band radiation means have used a burst signal to minimize uneven thawing. Burst signal radiation intermittently irradiates microwaves onto the frozen food, ensuring time for heat conduction within the food, thereby ensuring uniform thawing. The microwave thawing device according to the present disclosure can re-radiate HF or UHF band signals even when the carrier signal is burst-operated and irradiated intermittently. Therefore, uneven thawing can be further suppressed compared to conventional microwave thawing devices that irradiate only the 2400 MHz band.

[0043] As described above, in the first embodiment, by using the signal generating unit 1 composed of the modulator 2 and the solid-state power amplifier 3, and the re-radiation device 6 that extracts and re-radiates only the frequency component of the modulated signal from the signal, electromagnetic waves of different frequencies are irradiated by switching between the thawing process and other heating processes. As a result, an efficient thawing process can be achieved without increasing the size of the device. Note that although the effect can be obtained with one re-radiation device, installing multiple re-radiation devices improves efficiency.

[0044] Embodiment 2 10 is a diagram illustrating a configuration of a microwave processing device according to a second embodiment of the present disclosure. The microwave processing device according to the second embodiment includes a temperature monitor unit 20 that detects the temperature of the object 8 to be heated in addition to the configuration of the microwave processing device according to the first embodiment.

[0045] The temperature monitor unit 20 is electrically connected to the control unit 7. For example, the temperature monitor unit 20 includes an infrared sensor that detects infrared rays emitted from the object to be heated 8 to measure the surface temperature thereof in a non-contact manner. The temperature monitor unit 20 then transmits detection information based on the detected temperature distribution of the object to be heated 8 to the control unit 7.

[0046] Based on the comparison result between the preset target temperature and the detection information received from the temperature monitor unit 20, the control unit 7 determines the state of the object to be heated 8 during heating. Then, it controls the carrier wave signal generator 10, the modulation signal generator 11, and the modulation unit 2. For example, when the object to be heated 8 is in a frozen state, the carrier wave signal and the modulation signal are driven and amplitude-modulated as described above to intermittently irradiate the object to be heated with microwaves. When the detected temperature reaches or exceeds the target temperature, it is determined that the thawing of the object to be heated 8 is complete, and a signal with a modulation index M = 0 is input from the control unit 7 to the modulation unit 2. In this way, by driving only the carrier wave signal, only the 2400 MHz band signal used in normal heating is power-amplified by the solid-state power amplifier 3 to output a predetermined microwave power. The output is transmitted to the antenna 4 and radiated into the heating chamber 5.

[0047] Preferably, the above-mentioned target temperature is a value that can determine that the thawing of the object to be heated 8 is complete, for example, 0 °C. Note that the state where the thawing of the object to be heated 8 is complete is not limited to the state where the object to be heated 8 is completely thawed. For example, it also includes cases where the object to be heated 8 is in a desired state such as a semi-thawed state.

[0048] Also, the control based on the above target temperature may utilize the analysis result of the temperature change. The absorption rate of high-frequency electromagnetic waves changes depending on the melting state of the object to be heated 8. Since the temperature rise rate changes with this change, the thawing state can be grasped by detecting the inflection point of the temperature change. By performing a thawing process according to the thawing state, more accurate thawing control becomes possible.

[0049] In the second embodiment, as described above, based on the detection result of the temperature monitor, the carrier wave signal and the modulation signal are switched. As a result, appropriate microwave energy can be irradiated according to the state of the object to be heated.

[0050] Embodiment 3 11 is a diagram showing the configuration of a microwave processing device according to a third embodiment of the present disclosure. The microwave processing device according to the third embodiment includes a new solid-state power amplifier 3a and an antenna 4a in addition to the configuration of the microwave processing device according to the second embodiment. This makes it possible to simultaneously perform a thawing process using a modulated signal and another heating process using a carrier signal.

[0051] In the second embodiment, microwave energy is irradiated according to the state of the heated object by switching between a carrier signal and an amplitude-modulated signal. Therefore, the second embodiment is provided with only one set of a solid-state power amplifier 3 and an antenna 4. In other words, when thawing using a modulated signal, normal heating using only a carrier signal cannot be performed. However, since thawing using a modulated signal takes a relatively long time, there may be a need to simultaneously perform a thawing process using a modulated signal and another heating process using a carrier signal. In this embodiment, a microwave heating thawing device that can simultaneously perform a thawing process using a modulated signal and another heating process using a carrier signal will be described.

[0052] The microwave processing apparatus according to this embodiment includes a solid-state power amplifier 3a and an antenna 4a in addition to the configuration of the microwave processing apparatus according to embodiment 2. The solid-state power amplifier 3a amplifies the carrier signal 40a received from the carrier signal generator 10 and outputs the amplified carrier signal 51 to the antenna 4a. Therefore, the microwave 52 irradiated from the antenna 4a becomes the carrier signal 51.

[0053] As described above, by providing the new solid-state power amplifier and antenna, it is possible to simultaneously perform a thawing process using a modulated signal and another heating process using a carrier signal.

[0054] FIG. 12 is a diagram showing the configuration of a microwave processing apparatus according to a modified example of Embodiment 3 of the present disclosure. In addition to the configuration of FIG. 11, this microwave processing apparatus includes a new HF or UHF band modulation signal generator 12, a signal generation unit 1b, an antenna 4b, and a re-radiation device 6b. Thereby, it is possible to simultaneously perform thawing processes associated with a plurality of modulation signals.

[0055] The microwave processing apparatus according to this modified example includes a modulation signal generator 12 in addition to the configuration of the microwave processing apparatus of FIG. 11. The modulation signal generator 12 is an oscillation source in the HF or UHF band and generates a frequency different from that of the modulation signal generator 11. The modulation signal generator 12 generates a modulation signal 54 and outputs it to the modulation unit 2b. The modulation unit 2b amplitude-modulates the carrier signal 40b input from the carrier signal generator 10 using the input modulation signal 54. Then, the amplitude-modulated carrier signal 56 is input to the solid-state power amplifier 3b.

[0056] The solid-state power amplifier 3b amplifies the carrier signal 56 and outputs the amplified carrier signal 58 to the antenna 4b. The antenna 4b radiates the carrier signal 60 into the heating chamber 5. The carrier signal 60 is input to the re-radiation device 6b. The re-radiation device 6b is a re-radiation device configured to re-radiate the modulation signal of the modulation signal generator 12, whereby the modulation signal 62 is re-radiated into the heating chamber 5.

[0057] As described above, in this modified example, by providing a new HF band oscillation source, signal generation unit, antenna, and re-radiation device, it is possible to simultaneously perform thawing processes associated with a plurality of modulation signals.

[0058] In the solid-state power amplifier used in the present disclosure, at least one of the constituent semiconductor elements may be formed of a wide-bandgap semiconductor. The wide-bandgap semiconductor is, for example, silicon carbide, a gallium nitride-based material, or diamond. Since semiconductor elements formed of a wide-bandgap semiconductor have high breakdown voltage and allowable current density, it is possible to miniaturize semiconductor modules incorporating these elements.

[0059] The microwave processing apparatus disclosed herein can amplify the power of amplitude-modulated microwaves by a solid-state power amplifier and irradiate them, thereby irradiating microwaves suitable for the state of the object. That is, this technology is applicable to uses other than the heating device using dielectric heating as shown in the embodiments. Applicable examples include a microwave power supply used as a plasma power supply of a semiconductor manufacturing apparatus, an organic synthesis system in the chemical industry, and the like. In addition, the non-heating object and the heating chamber in the present disclosure correspond to the object to be processed and the processing chamber in the case of a microwave power supply, and the reactant and the reaction chamber in the case of an organic synthesis system.

[0060] In addition, since a solid-state power amplifier is used in the present disclosure, there is an advantage that phase control and power combining by it are possible. When microwaves are irradiated with a magnetron as in the prior art, the oscillation frequency fluctuates depending on the voltage applied to the magnetron and the impedance in the heating chamber, so it spreads over almost the entire 100 MHz bandwidth from 2400 MHz to 2500 MHz. However, when a solid-state power amplifier is used, microwave irradiation with a line spectrum without such noise components can be realized. Therefore, it is possible to significantly reduce the possibility of interfering waves with electronic devices around the microwave oven, particularly wireless LANs in the 2400 MHz band, and it is also possible to control the output power and phase. As described above, since the frequency stability and phase coherence are good, power combining by phase control is possible in space.

[0061] Since phase control is possible, it is possible to control the output such as selective area heating or uniform heating of the object to be heated. In addition, since power combining by it is possible, it is also possible to configure a high-output system. For example, the combined output power in the warehouse from a plurality of solid-state power amplifiers 3 may include 1000 watts or more. Also, for example, when a megawatt-class high output is required in an organic synthesis system, it can be realized by combining kilowatt-class solid-state power amplifiers.

Description of Reference Numerals

[0062] 2, 2b Modulation unit 3, 3a, 3b Solid state power amplifier 4, 4a, 4A, 4b, 4B Antenna 5 Heating chamber 6, 6a, 6b Re-radiation device 7 Control unit 8 Object to be heated 10 Carrier wave signal generator 11 Modulation signal generator 12 Modulation signal generator 20 Temperature monitor unit 21, 22 Antenna 23 Rectifier 24 Smoothing circuit 26 Amplifier 27 Smoothing circuit 40, 40a, 40b Carrier wave signal 42 Modulation signal 44, 46, 48 Carrier wave signal 50 Modulation signal 51 Carrier wave signal 52 Microwave 54 Modulation signal 56, 58, 60 Carrier wave signal 62 Modulation signal

Claims

1. A heating chamber for accommodating an object to be heated, A carrier wave signal generator for generating a carrier wave signal in the microwave band, A modulation signal generator for generating a modulation signal in the HF or UHF band, A modulation unit into which the carrier wave signal and the modulation signal are input, and which amplitude-modulates the carrier wave signal using the modulation signal, A first antenna for radiating the output signal output from the modulation unit into the heating chamber, A re-radiation device that receives the output signal, extracts the frequency component of the modulation signal from the received output signal, and re-radiates it into the heating chamber, A microwave processing apparatus comprising the same.

2. A solid-state power amplifier for power-amplifying the output signal, A control unit for controlling the amplitude modulation of the modulation unit The microwave processing apparatus according to Claim 1, comprising the same.

3. The re-radiation device is A second antenna for receiving the output signal, A rectifier for rectifying the output signal received by the second antenna, A smoothing circuit for smoothing the signal output from the rectifier and extracting a DC component, A third antenna for re-radiating the signal output from the smoothing circuit into the heating chamber The microwave processing apparatus according to any one of Claims 1 or 2, comprising the same.

4. The re-radiation device is A low-pass filter for extracting a frequency component from the signal output from the rectifier, An amplifier that uses the DC component as power supply power and amplifies the frequency component The microwave processing apparatus according to Claim 3, comprising the same.

5. The frequency of the carrier wave signal is 2450 MHz or 5800 MHz, The frequency of the modulation signal is 13.56 MHz or 860 - 960 MHz The microwave processing apparatus according to Claim 1.

6. Comprising a temperature monitor unit for detecting the surface temperature of the object to be heated The microwave processing apparatus according to Claim 1.

7. The semiconductor element constituting the solid-state power amplifier is formed of a wide bandgap semiconductor. The microwave processing apparatus according to Claim 2.

8. The wide bandgap semiconductor is silicon carbide, a gallium nitride-based material, or diamond. The microwave processing apparatus according to Claim 7.

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