Microwave treatment device

Abstract

The present disclosure relates to a microwave treatment device, and one objective of the present disclosure is to perform efficient defrosting treatment using an electromagnetic wave in an RF or UHF band without increasing the size of any peripheral equipment of the device.The microwave treatment device of the present disclosure comprises a heating chamber that receives an object to be heated, a carrier signal generator that generates a carrier signal in a microwave band, a modulation signal generator that generates a modulation signal in an HF or UHF band, a modulator into which the carrier signal and the modulation signal are fed, wherein the modulator modulates an amplitude of the carrier signal using the modulation signal; a first antenna that radiates an output signal emitted by the modulator into the heating chamber, and a back-radiation device that receives the output signal, extracts a frequency component of the modulation signal from the received output signal, and back-radiates the modulation signal into the heating chamber.

Description

Area

[0001] The present disclosure relates to a microwave treatment apparatus. background

[0002] It is known that a microwave oven, one of the microwave processing devices, is capable of uniform heating cooking using microwaves. On the other hand, defrosting using a microwave oven has problems such as uneven defrosting and cooking of the end or edge of a cooking object due to the different water and ice loss factors.

[0003] Patent Literature 1 discloses a method for simultaneously utilizing a microwave and a radio frequency wave as a means to solve this problem. The difference between the loss factors of water and ice is smaller in a frequency band lower than a microwave in the 2400 MHz band. Therefore, the microwave treatment apparatus described in Patent Literature 1 includes oscillation sources for the microwave and radio frequency (RF) bands. The microwave treatment apparatus performs radio wave irradiation in the RF band during the thawing treatment to perform efficient thawing treatment. Citation listPatent literature

[0004] [PTL 1] JP 2019-143868 A SummaryTechnical problem

[0005] However, to efficiently perform RF-band electromagnetic wave thawing treatment, it is necessary to irradiate an object to be heated using a plurality of antennas. Therefore, a problem arises in that the size of a peripheral device of the device increases.

[0006] To solve the above-described problem, the present disclosure utilizes a back-radiation device that extracts only a frequency component of the modulation signal from a carrier signal whose amplitude has been modulated using a modulation signal in an RF or ultra-high frequency (UHF) band, which has a lower frequency than a microwave band, and back-radiates the modulation signal. Therefore, an object of the present disclosure is to provide a microwave treatment device that can perform efficient thawing treatment using an electromagnetic wave in the RF or UHF band without increasing the size of a peripheral device of the device. Solution to the problem

[0007] The aspect of the present disclosure is preferably a microwave treatment apparatus comprising a heating chamber that accommodates an object to be heated, a carrier signal generator that generates a carrier signal in a microwave band, a modulation signal generator that generates a modulation signal in an HF or UHF band, a modulator to which the carrier signal and the modulation signal are input, the modulator modulating the amplitude of the carrier signal using the modulation signal, a first antenna that radiates an output signal output from the modulator into the heating chamber, and a retro-radiating device that receives the output signal, extracts a frequency component of the modulation signal from the received output signal, and retro-radiates the modulation signal into the heating chamber. Advantageous effects of the invention

[0008] According to the aspect of the present disclosure, a microwave treatment apparatus can be provided that can perform efficient thawing treatment using an electromagnetic wave in the RF or UHF band without increasing the size of a peripheral equipment of the apparatus. Short description of the drawings Fig. 1 is a diagram illustrating a configuration of a prior art microwave oven. Fig. 2 is a diagram illustrating a prior art configuration of a cooking device for heating using an electromagnetic wave in the RF band. Fig. 3 is a diagram illustrating a configuration of a prior art microwave treatment apparatus in connection with a problem solution. Fig. 4 is a diagram illustrating a configuration of a prior art microwave treatment apparatus in connection with a problem solution. Fig. 5 is a diagram illustrating a configuration of a microwave processing apparatus according to a first embodiment of the present disclosure. Fig. 6 is a diagram illustrating a configuration of the retro-reflection device according to the first embodiment. Fig. 7 is a diagram illustrating a modification of the retro-reflection device according to the first embodiment. Fig. Figure 8 is a graph illustrating a waveform of the signal s(t) in the case of modulation index M=1. Fig. Figure 9 is a graph illustrating a frequency spectrum of the signal s(t) in the case where the modulation index M is changed. Fig. 10 is a diagram illustrating a configuration of a microwave processing apparatus according to a second embodiment of the present disclosure. Fig. 11 is a diagram illustrating a configuration of a microwave processing apparatus according to a third embodiment of the present disclosure. Fig. 12 is a diagram illustrating a configuration of a microwave processing apparatus according to a modification of the third embodiment of the present disclosure. Description of EmbodimentsFirst Embodiment[Configuration of a Prior Art Example]

[0009] Before explaining a first embodiment, a configuration of a prior art example will be explained as background. As a method for storing food, frozen storage of perishable goods such as meat and seafood, cooked foods, and the like is widely used. Particularly in recent years, the improvement of freezing technology has made it possible to store food for a long period of time in a state where the freshness of the food is maintained. Accordingly, the demand for a defrosting device that can perform defrosting treatment without impairing freshness has increased. As such a defrosting device, a so-called microwave oven is known.

[0010] Fig. 1 is a diagram illustrating a configuration of a prior art microwave oven. The microwave oven is a microwave processing device that generally uses a 2450 MHz microwave and can perform defrosting and heating. The prior art 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 causes the magnetron to generate an electromagnetic wave 30A according to a control signal from a control unit 7. The electromagnetic wave 30A is radiated into a heating chamber 5 via an antenna 4A. In the heating chamber 5, an object 8 to be heated is placed on a support table 9 and is heated by the electromagnetic wave 30A.

[0011] The microwave used for high-frequency heating uses an ISM (Industrial, Scientific, and Medical) band. The magnetron's oscillation frequency is set to a predetermined value, for example, in a range of 2400 MHz to 2500 MHz. By using the microwave, a generally uniform treatment can be achieved for heating a cooking object.

[0012] However, for defrosting cooking, a generally uniform treatment sometimes cannot be achieved with simple microwave irradiation. One example of this is the large difference in the energy absorption coefficient between water and ice, which is an indicator of energy absorption efficiency. For example, in a 2450 MHz microwave oven, the energy absorbed by water is 1,000 times that absorbed by ice. Therefore, a large difference in the energy absorbed occurs between the peripheral edge of a cooking object, which melts in the early stages of defrosting, and the center of the cooking object, which does not melt in the early stages of defrosting.As a result, phenomena that cause quality deterioration, such as unevenness in defrosting in which a heating state is uneven at the peripheral edge area and the center of the cooking object, and cooking in which only the peripheral edge area is excessively heated, occur.

[0013] To solve these problems, Patent Literature 1 discloses a cooking device for heating that efficiently performs defrosting treatment using an electromagnetic wave in a high frequency (RF) band. It is known that the difference between the loss factors of water and ice in a low frequency RF band is relatively smaller than that in a high frequency microwave. Therefore, in Patent Literature 1, defrosting treatment is more efficiently performed by using an electromagnetic wave in the RF band, such as 13560 kHz, at the time of defrosting treatment, instead of using microwaves.

[0014] Fig. Figure 2 is a diagram illustrating a configuration of a heating cooking device using an electromagnetic wave in the RF band according to the prior art. A configuration of a heating cooking device that controls a microwave and an electromagnetic wave in an RF band according to a state of a heating object, as disclosed in Patent Literature 1, is described with reference to Fig. 2 explained.

[0015] First, cooking for heating, with the exception of thawing, will be explained. The cooking device for heating contains an oscillator 10A. The oscillator 10A causes a magnetron to generate an electromagnetic wave 30A in accordance with a control signal from the control unit 7. The electromagnetic wave 30A is radiated into the heating chamber 5 via the antenna 4A. In the heating chamber 5, the object 8 to be heated is placed on a support table 9 and is heated by the electromagnetic wave 30A. This also applies to the Fig. 1 illustrates a prior art microwave oven.

[0016] Next, the defrosting treatment will be explained. The heating device includes an oscillator 11A, different from the oscillator 10A. The oscillator 11A is an oscillation source with any frequency among 13560 kHz, 27120 kHz, and 40.68 MHz, corresponding to the HF band of the ISM band. According to a control signal from the control unit 7, the oscillator 11A causes the magnetron to generate an electromagnetic wave 30B. The electromagnetic wave 30B is radiated into the heating chamber 5 via an antenna 4B and defrosts the object 8 to be heated.

[0017] As explained above, the Fig. The heating cooking apparatus illustrated in Patent Document 2 uses the same microwave as the prior art microwave oven for heating cooking except for the defrosting treatment, and uses the RF band electromagnetic wave for the defrosting treatment. Therefore, Patent Document 1 provides a heating cooking apparatus capable of efficient defrosting treatment. [Problems of the prior art example]

[0018] The following explains the problems of the prior art example. As one example of the problems of the prior art example, an increase in the size of an apparatus is unavoidable in order to improve the efficiency of thawing treatment using the RF band electromagnetic wave.

[0019] When a microwave oven is used for home use, a standing wave is generated inside the microwave oven's casing. Part of the emitted microwave is absorbed by the object being heated, and the rest is reflected inside the casing. This results in a reflected wave from the microwave portion combining with an incident wave. Since the internal dimensions of the casing are 30 cm to 40 cm, in the case of a 2400 MHz microwave, whose wavelength in a vacuum is 12.5 cm, a standing wave of the microwave may be present inside the casing.

[0020] However, in the case of a 13560 kHz microwave, whose wavelength in vacuum is 2300 cm, no standing wave is generated in the enclosure and the environment inside the enclosure represents a near field. In the near field, the radiation efficiency is higher when an antenna area is larger or a larger number of antennas are installed.

[0021] Fig. 3 and Fig. 4 are diagrams illustrating a configuration of a prior art microwave treatment apparatus in connection with a problem solution. As explained above, in order to efficiently perform the thawing treatment with the 13560 kHz electromagnetic wave, it is necessary to irradiate the object to be heated from the plurality of antennas. For example, a method in which Fig. 3 illustrates a plurality of sets of oscillators 11A and antennas 4B are installed, and a method in which as in Fig. 4 illustrates an oscillation output of the oscillator 11A distributed and electricity fed to a plurality of antennas 4B. However, these two methods lead to a problem of increasing the size of a peripheral device of the heating chamber 5. In the present disclosure, a microwave treatment apparatus is provided that solves this problem. [Configuration of a first embodiment]

[0022] Fig. 5 is a diagram illustrating a configuration of a microwave processing apparatus according to a first embodiment of the present disclosure. The microwave processing apparatus according to the first embodiment includes a carrier signal generator 10. The carrier signal generator 10 generates a carrier signal 40 and outputs the carrier signal 40 to a modulator 2. A frequency of the carrier signal 40 is preferably 2450 MHz or 5800 MHz in the ISM band.

[0023] The microwave treatment apparatus includes a modulation signal generator 11. The modulation signal generator 11 generates a modulation signal 42 and outputs the modulation signal to the modulator 2. A frequency of the modulation signal 42 is sufficiently lower than the frequency of the carrier signal 40. The frequency of the modulation signal 42 is preferably 13.56 MHz in the HF band or 860 to 960 MHz in the UHF band, whose international compatibility is ensured by the radio communication standard, and may be one of 27120 kHz, 40.68 MHz, or 100±10 MHz.

[0024] The modulator 2 performs amplitude modulation on the input carrier signal 40 using the input modulation signal 42. The modulator 2 is implemented, for example, by a method using a nonlinear element to connect a modulation signal amplifier and a carrier oscillator output in series to apply a signal to the nonlinear element, or by switching modulation. The modulator 2 feeds an amplitude-modulated carrier signal 44 into a solid-state power amplifier 3.

[0025] The solid-state power amplifier 3 amplifies the carrier signal 44 and outputs an amplified carrier signal 46 to the antenna 4. In the solid-state power amplifier 3, a dielectric substrate is configured using a low dielectric loss material, and a circuit is configured using a conductor pattern formed on a surface of the dielectric substrate. To make semiconductor elements, which are amplifying elements, operate satisfactorily, matching circuits are arranged on the input and output sides of the semiconductor elements, respectively. The semiconductor elements can be implemented by, for example, a HEMT (High Electron Mobility Transistor), a MOSFET such as a lateral diffusion metal-oxide-semiconductor field-effect transistor (LDMOSFET), or a bipolar junction transistor (BJT).Note that the semiconductor elements are not limited to a specific type.

[0026] The antenna 4 radiates the carrier signal 46 into the heating chamber 5. A retro-radiating device 6 receives a radiated carrier signal 48 and extracts a frequency component of a modulation signal to re-radiate the modulation signal 50 into the heating chamber 5. The operation of the retro-radiating device 6 is explained below.

[0027] The control unit 7 is connected to the carrier signal generator 10, the modulation signal generator 11, and the modulator 2. The control unit 7 controls the ON and OFF of a signal, a frequency of a signal to be generated, the output of a signal, and the like to control the operation of the carrier signal generator 10 and the modulation signal generator 11. Furthermore, the control unit 7 controls the operation of the modulator 2 to implement a change in a modulation index M and a burst operation, which will be explained below.

[0028] A microwave transmission line connecting the respective functional blocks forms a transmission circuit whose characteristic impedance is 50 Ω, wherein the conductor structure is arranged on a surface of the dielectric substrate.

[0029] Fig. 6 is a diagram illustrating a configuration of the retro-reflecting device according to the first embodiment. The retro-reflecting device 6 extracts a frequency component of a modulation signal using RFID (Radio Frequency Identification) technology. The retro-reflecting device 6 includes an antenna 21 that receives an electromagnetic wave in a microwave band. The antenna 21 receives the carrier signal 48 in the microwave band radiated from the antenna 4 into the heating chamber 5 and outputs the carrier signal 48 to a rectifier 23.

[0030] The rectifier 23 outputs the input carrier signal 48 to a smoothing circuit 24 and a low-pass filter (LPF) 25. The rectifier 23 can be implemented, for example, using a half-wave rectifier or a full-wave rectifier using a diode.

[0031] The smoothing circuit 24 smooths the input carrier signal, extracts a DC component, and provides the carrier signal to an amplifier 26 as a power source. The LPF 25 extracts a frequency component of the modulation signal from the input carrier signal and provides the modulation signal to the amplifier 26. The amplifier 26 amplifies the frequency component of the modulation signal extracted by the LPF 25. The amplifier 26 reradiates the amplified modulation signal 50 into the heating chamber 5 via an antenna 22.

[0032] Fig. Figure 7 is a diagram illustrating a modification of the retro-reflective device according to the first embodiment. A retro-reflective device 6a includes an envelope detection circuit formed by a rectifier 23 and a smoothing circuit 27. The modulation signal 50 is re-radiated into the heating chamber 5 by the circuit in the same manner as by the retro-reflective device 6. [Operation of the first embodiment]

[0033] Next, an operation will be explained. A frequency of a carrier signal in the first embodiment is a 2400 MHz band of a microwave band and is represented as fc below. This is the same as a frequency of a general microwave heating device, a so-called microwave oven in Japan. A frequency of a modulation signal according to the first embodiment is 13.56 MHz in the RF band and is represented as fm below.

[0034] During cooking for heating, since only the carrier signal is used, as in the prior art microwave oven, amplitude modulation using the modulation signal is not performed. On the other hand, during cooking for defrosting, a signal amplitude-modulated using the modulation signal is applied. In this case, a signal s(t) output by modulator 2 can be represented by the following expression. s(t)=A{1+Mcos(2πfmt)}cos(2πfct)

[0035] In Math. 1, A represents an amplitude constant, M represents a modulation index, and t represents time. The modulation index M satisfies 0≤M≤1. In the case of M=0, s(t) is an unmodulated sine wave.

[0036] In the case of M>0, the amplitude of s(t) fluctuates and a frequency spectrum of s(t) has three peaks. Fig. Figure 8 is a graph illustrating a waveform of the signal s(t) in the case of the modulation index M=1. In this case, an amplitude component of a wave of an amplitude modulation signal fluctuates as shown in Fig. 8 is illustrated. Fig. Figure 9 is a graph illustrating a frequency spectrum of the signal s(t) in the case where the modulation index M is changed. Here, waveforms are illustrated in the case where the modulation index M is changed to 0.1 and 0.5. It can be seen that the magnitude of the fluctuation of the waveforms changes according to a value of the modulation index M. A frequency of a main peak is fc of a carrier frequency. Sidebands, which are peaks present at both ends of the frequency, are generated at equally separated positions centered on fc as fc±fm. In this way, an amplitude component of fc does not change, and only the amplitude of the sidebands has the property of being M / 2. The average power of this carrier is given by A. 2 / 2 given.

[0037] By changing the value of the modulation index M, it is possible to adjust the electrical power in the RF band to be effective for defrosting. This change corresponds to a change in the output power of fm. It is possible to perform uniform defrosting without unevenness by, for example, using M=1 with maximum output power in an early stage of defrosting and using M=0.5 in a later stage of defrosting.

[0038] The carrier signal 48 emitted by the antenna 4 comprises three 2400 MHz band signals fc-fm, fc, and fm+fc, which are formed by the carrier frequency fc in the 2400 MHz band and the modulation signal fm in the HF or UHF band. The object 8 to be heated is irradiated with the three 2400 MHz band signals, and the three 2400 MHz band signals are fed into the retro-reflective device 6 arranged in the heating chamber 5. In the retro-reflective device 6 with the Fig. In the configuration illustrated in Figure 6, the modulation signal 50, which is the signal fm in the HF or UHF band, is reflected by the antenna 22. The object 8 to be heated is also irradiated with the modulation signal 50.

[0039] Since the electrical power of the back-radiation device 6 is provided by smoothing an input microwave band, a power distribution device and wires incorporated in the power distribution device, or an oscillator dedicated to the HF or UHF band, are unnecessary. Therefore, it is possible to irradiate the object 8 to be heated with a signal in the HF or UHF band suitable for thawing without increasing the size of the peripheral equipment outside the heating chamber 5, simply by adding the back-radiation device utilizing RFID technology. By installing a plurality of units of a back-radiation device in the heating chamber 5, it is possible to irradiate the object 8 to be heated with signals in the HF or UHF band from different directions. As a result, it is possible to efficiently realize thawing while suppressing an increase in the size of the peripheral equipment.

[0040] Note that the carrier signal is a burst mode instead of a continuous wave, illustrated in Fig. 8. In a microwave heating apparatus that does not have a radiation means in the RF band, a method of utilizing burst operation has been used to prevent uneven cooking for defrosting as much as possible. With burst operation, uniform defrosting treatment can be expected because the time for heat conduction within a cooking object can be ensured by intermittently irradiating a frozen cooking object with a microwave. A microwave heating and defrosting apparatus according to the present disclosure can perform back radiation in the RF or UHF band even when burst operation of the carrier signal is initiated and irradiation of the carrier signal is performed intermittently.Therefore, it is possible to further suppress the occurrence of unevenness in thawing and the like as compared with a prior art microwave heating and thawing apparatus that performs irradiation with only the 2400 MHz band.

[0041] In the first embodiment, as explained above, irradiation of electromagnetic waves with different frequencies is performed by switching the electromagnetic waves at the time of one thawing treatment and another heating treatment, using a signal generator 1 configured with the modulator 2 and the solid-state power amplifier 3, and the retro-radiating device 6 that extracts only a frequency component of a modulation signal from a signal and retro-radiates the modulation signal. As a result, it is possible to realize efficient thawing treatment without increasing the size of the device. Note that although the effect can be obtained even by using one retro-radiating device, the efficiency is improved if a plurality of retro-radiating devices are installed. Second embodiment

[0042] Fig. 10 is a diagram illustrating a configuration of a microwave processing apparatus according to a second embodiment of the present disclosure. The microwave processing apparatus according to the second embodiment includes, in addition to the components of the microwave processing apparatus according to the first embodiment, a temperature monitoring device 20 that detects the temperature of the object 8 to be heated.

[0043] The temperature monitoring device 20 is electrically connected to the control unit 7. For example, the temperature monitoring device 20 contains an infrared sensor that detects infrared radiation emitted by the object 8 to be heated in order to measure the surface temperature of the object 8 to be heated without contact. The temperature monitoring device 20 transmits detection information based on a detected temperature distribution of the object 8 to be heated to the control unit 7.

[0044] The control unit 7 determines a state of the object 8 to be heated during heating based on a comparison result of a preset target temperature and the detection information received from the temperature monitoring device 20. The control unit 7 controls the carrier signal generator 10, the modulation signal generator 11, and the modulator 2. For example, when the object 8 to be heated is frozen, as explained above, the control unit 7 controls the carrier signal and the modulation signal and modulates the amplitude to intermittently irradiate the object to be heated with the microwave. When the detected temperature is equal to or higher than the target temperature, the control unit 7 determines that the thawing of the object 8 to be heated has been completed and inputs a signal to the modulation index M=0 to the modulator 2.By controlling only the carrier signal in this way, the solid-state power amplifier 3 amplifies only the power of a signal used during normal heating in the 2400 MHz band and outputs a predetermined microwave power. The output signal is transmitted to the antenna 4 and radiated into the heating chamber 5.

[0045] The target temperature explained above is preferably a value with which it is possible to determine that the thawing of the object 8 to be heated has been completed, and is set to, for example, 0°C. Note that the state in which the thawing of the object 8 to be heated is completed is not limited to a state in which the object 8 to be heated is completely thawed. The state in which the thawing of the object 8 to be heated is completed includes a case in which the object 8 to be heated is in a desired state, such as a half-thawed state.

[0046] Target temperature-based control may be control that utilizes the analysis result of a temperature change. The absorption ratio of a high-frequency electromagnetic wave changes according to the melting state of the object 8 to be heated. Since the temperature rise ratio changes according to the change, it is possible to detect a thawed state by detecting an inflection point of the temperature change. It is possible to perform more precise control of the thawing process or defrosting by performing defrosting treatment according to the thawed state.

[0047] In the second embodiment, as explained above, the carrier signal and the modulation signal are switched based on the detection result of the temperature monitoring device. As a result, it is possible to irradiate appropriate microwave energy according to the condition of the object to be heated. Third embodiment

[0048] Fig. 11 is a diagram illustrating a configuration of a microwave processing apparatus according to a third embodiment of the present disclosure. The microwave processing apparatus according to the third embodiment includes a novel solid-state power amplifier 3a and a novel antenna 4a in addition to the components of the microwave processing apparatus according to the second embodiment. This makes it possible to simultaneously perform a defrosting treatment using a modulation signal and another heating treatment using a carrier signal.

[0049] In the second embodiment, microwave energy irradiation is performed according to the state of the object to be heated by switching the carrier signal and the amplitude modulation signal. Therefore, in the second embodiment, the microwave treatment apparatus comprises only one set of the solid-state power amplifier 3 and the antenna 4. That is, when thawing is performed using the modulation signal, normal heating using only the carrier signal cannot be performed. Since thawing using the modulation signal takes a long time, it is also conceivable to simultaneously perform the thawing treatment using the modulation signal and the other heating treatment using the carrier signal.In this embodiment, a microwave heating and thawing apparatus capable of simultaneously performing the thawing treatment using the modulation signal and the other heating treatment using the carrier signal is explained.

[0050] The microwave treatment apparatus according to this embodiment includes, in addition to the components of the microwave treatment apparatus according to the second embodiment, a solid-state power amplifier 3a and an antenna 4a. The solid-state power amplifier 3a amplifies a carrier signal 40a received from the carrier signal generator 10 and outputs an amplified carrier signal 51 to the antenna 4a. Therefore, a microwave 52 irradiated from the antenna 4a is the carrier signal 51.

[0051] Since the microwave treatment apparatus has the novel solid-state power amplifier and the novel antenna as explained above, it is possible to simultaneously perform the treatment for thawing using the modulation signal and the other treatment for heating using the carrier signal.

[0052] Fig. 12 is a diagram illustrating a configuration of a microwave processing apparatus according to a modification of the third embodiment of the present disclosure. The microwave processing apparatus includes, in addition to the Fig. The components illustrated in Figure 11 include a new modulation signal generator 12 for an HF or UHF band, a new signal generator 1b, a new antenna 4b, and a retro-reflective device 6b. This makes it possible to perform a thawing treatment associated with a plurality of modulation signals simultaneously.

[0053] The microwave treatment apparatus according to this modification comprises, in addition to the components of the microwave treatment apparatus described in Fig. 11, the modulation signal generator 12. The modulation signal generator 12 is an oscillation source of the HF or UHF band and generates a frequency that differs from the frequency generated by the modulation signal generator 11. The modulation signal generator 12 generates a modulation signal 54 and outputs the modulation signal 54 to a modulator 2b. The modulator 2b performs amplitude modulation on a carrier signal 40b input from the carrier signal generator 10 using the input modulation signal 54. The modulator 2b inputs an amplitude-modulated carrier signal 56 to a solid-state power amplifier 3b.

[0054] The solid-state power amplifier 3b amplifies the carrier signal 56 and outputs an amplified carrier signal 58 to the antenna 4b. The antenna 4b radiates a carrier signal 60 into the heating chamber 5. The carrier signal 60 is fed into the retro-radiating device 6b. The retro-radiating device 6b is a retro-radiating device configured to retro-radiate a modulation signal from the modulation signal generator 12. Consequently, a modulation signal 62 is retro-radiated into the heating chamber 5.

[0055] In this modification, as explained above, the microwave treatment apparatus includes the new RF band oscillation source, the new signal generator, the new antenna, and the new retro-radiation device. Therefore, it is possible to simultaneously perform thawing treatment associated with a plurality of modulation signals.

[0056] In the solid-state power amplifier used in the present disclosure, at least one of the semiconductor elements constituting the solid-state power amplifier may be formed from a wide-bandgap semiconductor. The wide-bandgap semiconductor is, for example, a silicon carbide- or gallium nitride-based material, or diamond. Semiconductor elements formed using the wide-bandgap semiconductor have the property of high withstand voltage and high allowable current density. Therefore, the size of a semiconductor module including these elements can be reduced.

[0057] The microwave processing apparatus explained in the present disclosure can perform microwave irradiation appropriate to the condition of a target object by amplifying the power of an amplitude-modulated microwave with a solid-state power amplifier and performing microwave irradiation. That is, this technique is also applicable to uses other than the heating apparatus using dielectric heating explained in the embodiment. Applicable examples include a microwave power supply used as a plasma power supply of a semiconductor manufacturing apparatus and an organic synthesis system in the chemical industry.Note that in the present disclosure, the object to be heated and the heating chamber correspond to an object to be treated and a treatment chamber in the case of the microwave power supply, and to a reaction object and a reaction chamber in the case of the organic synthesis system.

[0058] Note that since the solid-state power amplifier is used in the present disclosure, there is an advantage that phase control and power synthesis are possible through the phase control. When irradiation of a microwave is performed using the magnetron as in the prior art, an oscillation frequency of the microwave fluctuates according to a voltage applied to the magnetron and an impedance in the heating chamber. Therefore, the microwave propagates over substantially the entire 100 MHz bandwidth from 2400 MHz to 2500 MHz. However, when the solid-state power amplifier is used, microwave irradiation of a line spectrum without such a noise component can be realized.Therefore, it is possible to greatly reduce the possibility of the microwave becoming an interference wave for electromagnetic equipment around a microwave oven, especially a wireless LAN in the 2400 MHz band, and it is possible to control the output power and a phase. Since the frequency stability and phase coherence are satisfactory as explained above, power synthesis using phase control in space is possible.

[0059] Because phase control is possible, output control for the object to be heated is possible, such as selective or targeted area heating and uniform heating. Because power synthesis is possible through power control, it is also possible to configure a system with high output power. For example, the synthetic output power in one chamber from a plurality of solid-state power amplifiers can be 1000 watts or more. For example, when a megawatt-class high output power is required in the organic synthesis system, the high output power can be achieved by synthesizing a kilowatt-class solid-state power amplifier. List of reference symbols

[0060] 2, 2b Modulator, 3, 3a, 3b Solid-state power amplifier, 4, 4a, 4A, 4b, 4B Antenna, 5 Heating chamber, 6, 6a, 6b Retroreflective device, 7 Control unit, 8 Object to be heated, 10 Carrier signal generator, 11 Modulation signal generator, 12 Modulation signal generator, 20 Temperature monitoring device, 21, 22 Antenna, 23 Rectifier, 24 Smoothing circuit, 26 Amplifier, 27 Smoothing circuit, 40, 40a, 40b Carrier signal, 42 Modulation signal, 44, 46, 48 Carrier signal, 50 Modulation signal, 51 Carrier signal, 52 Microwave, 54 Modulation signal, 56, 58, 60 Carrier signal, 62 Modulation signal QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-143868 A

[0004]

Claims

[1] Microwave treatment device, comprising: a heating chamber that holds an object to be heated, a carrier signal generator that generates a carrier signal in a microwave band, a modulation signal generator that generates a modulation signal in an HF or UHF band; a modulator to which the carrier signal and the modulation signal are input, the modulator modulating an amplitude of the carrier signal using the modulation signal; a first antenna that radiates an output signal from the modulator into the heating chamber; and a retro-radiating device that receives the output signal, extracts a frequency component of the modulation signal from the received output signal, and re-radiates the modulation signal into the heating chamber. [2] A microwave treatment apparatus according to claim 1, further comprising: a solid-state power amplifier that amplifies the power of the output signal; and a control unit that controls the amplitude modulation of the modulator. [3] A microwave treatment apparatus according to claim 1 or 2, wherein the retro-radiation device comprises: a second antenna that receives the output signal; a rectifier that rectifies the output signal received from the second antenna; a smoothing circuit that smoothes a signal output from the rectifier and extracts a DC component; and a third antenna that reflects a signal emitted by the smoothing circuit back into the heating chamber. [4] A microwave treatment apparatus according to claim 3, wherein the retro-radiation device comprises: a low-pass filter that extracts a frequency component from the signal output by the rectifier; and an amplifier that uses the DC component as power supply and amplifies the frequency component. [5] Microwave treatment apparatus according to claim 1, wherein the carrier signal has a frequency of 2450 MHz or 5800 MHz and the modulation signal has a frequency of 13.56 MHz or 860 to 960 MHz. [6] The microwave treatment apparatus according to claim 1, further comprising a temperature monitoring device that detects a surface temperature of the object to be heated. [7] A microwave processing apparatus according to claim 2, wherein a semiconductor element constituting the solid-state power amplifier is formed of a wide band gap semiconductor. [8] A microwave processing apparatus according to claim 7, wherein the wide band gap semiconductor is silicon carbide or gallium nitride based material or diamond.

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