Signal output device, microwave oven, refrigerator and freezer

Abstract

The present disclosure addresses the problem of achieving high performance even when microwaves are applied to foods and beverages. A signal output device (1) outputs an oscillating signal for generating microwaves applied to foods and beverages. The signal output device (1) comprises: an oscillator (20); a phase shifter (e.g., a first phase shifter 40); and a phase control unit (50). The oscillator (20) outputs an oscillation signal to an antenna, and microwaves are applied through the antenna. A phase shifter is provided to the output position of the oscillator (20) and changes the load impedance from the oscillator (20) to the antenna. A phase control unit (50) controls the phase shifter so as to change a load impedance of the oscillator (20) in accordance with an oscillation frequency of the oscillation signal.

Description

Technical Field

[0001] The present disclosure generally relates to a signal output device, a microwave oven, a refrigerator, and a freezer, and more particularly to a signal output device configured to output an oscillation signal for generating microwaves to irradiate edibles and drinkables, as well as a microwave oven, a refrigerator, and a freezer. Background Art

[0002] A transmitter is known in the prior art that contributes to improving the performance of a mobile wireless device even when an isolator is omitted (for example, see Patent Document 1).

[0003] In the transmitter of Patent Document 1, the output signal of a digital modulator is split into n signals. These signals are then passed through n input phase shifters, each of which produces a different phase shift. These n signals are then amplified by n power amplifiers. Thereafter, these n signals are passed through n output phase shifters and combined by these output phase shifters to match their phases. Finally, the combined and phase-matched signals are output through the output terminal.

[0004] In Patent Document 1, the frequency of the output signal used in wireless communication is predetermined. On the other hand, in electrical devices that irradiate edible and drinkable items with microwaves (e.g., microwave ovens), the frequency of the radiated microwaves is variable. Therefore, it is difficult to apply the technology of Patent Document 1 to electrical devices that irradiate edible and drinkable items with microwaves.

[0005] Reference List

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 9-64758 Summary of the Invention

[0008] In view of the foregoing background, it is therefore an object of the present disclosure to provide a signal output device, a microwave oven, a refrigerator, and a freezer that contribute to improved performance even when edibles and drinkables are irradiated with microwaves.

[0009] According to one aspect of the present disclosure, a signal output device outputs an oscillating signal for generating microwaves for irradiating edibles and drinkables. The signal output device includes an oscillator, a phase shifter, and a phase control unit. The oscillator outputs the oscillating signal to an antenna that radiates the microwaves. The phase shifter is positioned at the oscillator's output position to change the load impedance of the antenna as viewed from the oscillator. The phase control unit controls the phase shifter so that it changes the load impedance of the oscillator according to the oscillation frequency of the oscillating signal.

[0010] A microwave oven according to another aspect of the present disclosure includes the above-described signal output device and a storage container. The storage container stores an object to be a target irradiated with microwaves that are radiated from the signal output device via an antenna.

[0011] A refrigerator according to still another aspect of the present disclosure includes the above-described signal output device and a storage container. The storage container stores an object to be a target irradiated with microwaves that are radiated from the signal output device via an antenna.

[0012] A freezer according to yet another aspect of the present disclosure includes the above-described signal output device and a storage container. The storage container stores an object to be a target irradiated with microwaves that are radiated from the signal output device via an antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a block diagram illustrating the configuration of the signal output device according to the first embodiment.

[0014] Figure 2 is a block diagram illustrating the configuration of an electrical device including the signal output device.

[0015] Figure 3 is a Smith chart illustrating the impedance characteristics of the antenna.

[0016] Figure 4 A is a Smith chart illustrating the load impedance characteristics of the frequency of the oscillation signal output from the signal output device. Figure 4 B is a Smith chart illustrating the load impedance characteristics of the output power of the oscillation signal output from the signal output device.

[0017] Figure 5 A is a Smith chart illustrating the load impedance characteristics of the frequency of the oscillation signal output from the signal output device according to the comparative example. Figure 5 B is a Smith chart illustrating the load impedance characteristics of the output power of the oscillation signal output from the signal output device according to the comparative example.

[0018] Figure 6 is a block diagram illustrating the configuration of the signal output device according to the second embodiment. DETAILED DESCRIPTION

[0019] Note that the embodiments and their modifications to be described below are merely exemplary embodiments among various embodiments of the present disclosure, and their modifications should not be construed as limitations. Instead, the exemplary embodiments and their modifications can be easily modified in various ways according to design choices or any other factors without departing from the scope of the present disclosure.

[0020] (First Embodiment)

[0021] Now, reference will be made to Figures 1 to 5 B to describe the signal output device 1 and the electrical device 2 according to the first embodiment.

[0022] (1) Overview

[0023] The signal output device 1 according to the first embodiment is designed to irradiate an irradiation target such as an edible or a drinkable with high-power microwaves. The signal output device 1 is applied to, for example, the electrical device 2. In this example, the electrical device 2 is a microwave oven, a refrigerator, or a freezer. Figure 2 The case where the signal output device 1 is applied to the microwave oven 2a as an exemplary electrical device 2 is shown. When applied to the microwave oven 2a, the signal output device 1 heats the edible and the drinkable with high-power microwaves.

[0024] The signal output device 1 according to the first embodiment outputs an oscillation signal for generating microwaves to irradiate the edible and the drinkable. The signal output device 1 outputs the oscillation signal to an antenna 100 (refer to Figure 2 ) that is electrically connected to the signal output device 1, and then radiates microwaves corresponding to the oscillation signal via the antenna 100. As Figure 1 shown, the signal output device 1 includes an oscillator 20, a first phase shifter 40 (phase shifter), and a phase control unit 50. The oscillator 20 outputs an oscillation signal to the antenna 100 (refer to Figure 2 ) that radiates microwaves. The first phase shifter 40 is provided at the output position (destination) of the oscillator 20 to change the load impedance of the antenna 100 as observed from the oscillator 20. The phase control unit 50 controls the first phase shifter 40 so that the first phase shifter 40 changes the load impedance of the oscillator 20. More specifically, the phase control unit 50 controls the first phase shifter 40 so that the first phase shifter 40 changes the load impedance of the oscillator 20 according to the oscillation frequency of the oscillation signal.

[0025] This configuration allows appropriate microwaves to be radiated according to the frequency of the oscillation signal. Therefore, this configuration helps to improve the performance even when irradiating the edible and the drinkable with microwaves.

[0026] (2) Configuration

[0027] Now, the configurations of the electrical device 2 and the signal output device 1 according to the first embodiment will be described.

[0028] As Figure 2 shown, the electrical device 2 includes the signal output device 1 and a storage container 3. The storage container 3 stores an object (edible and drinkable) that serves as a target to be irradiated with microwaves, and the microwaves are radiated from the signal output device 1 via the antenna 100.

[0029] As Figure 2As shown, the electrical device 2 according to the first embodiment includes one or more (e.g., two in the Figure 2 illustrated example) signal output devices 1 and a plurality of (e.g., two in the Figure 2 illustrated example) antennas 100. One or more antennas 100 are respectively associated with one or more signal output devices 1 in a one-to-one manner. The electrical device 2 includes a storage container 3. The storage container 3 stores objects (edible and drinkable items) that are targets to be irradiated with microwaves, and the microwaves are radiated from the signal output device 1 via the antenna 100. Each of the antennas 100 is provided for the storage container 3.

[0030] If the electrical device 2 is a microwave oven 2a, one or more signal output devices 1 heat the irradiation target (e.g., edible and drinkable items) stored in the storage container 3 by irradiating the irradiation target with microwaves via the antenna 100.

[0031] Note that if the electrical device 2 is a refrigerator, one or more signal output devices 1 change an object (edible and drinkable items) stored in the refrigerator to a mature state by irradiating the object with microwaves via the antenna 100. In addition, one or more signal output devices 1 change an object (edible and drinkable items) refrigerated below the freezing point to a supercooled state by irradiating the object with microwaves via the antenna 100. As used herein, the "supercooled state" refers to a state in which a liquid such as water is cooled below the freezing point (the temperature at which the liquid freezes and becomes a solid) but does not freeze. For example, water naturally freezes at a temperature equal to or below zero degrees. However, in the supercooled state, if certain conditions are met, such as water not freezing even at a temperature equal to or below zero degrees, water can be kept cooled without freezing.

[0032] Furthermore, if the electrical device 2 is a freezer, one or more signal output devices 1 instantaneously freeze an object (edible and drinkable items) that has been refrigerated below the freezing point (i.e., has been kept in a supercooled state) with microwaves via the antenna 100 by stopping the radiation of microwaves.

[0033] Each of the one or more signal output devices 1 (hereinafter simply referred to as "signal output device 1") according to the first embodiment generates an oscillation signal, outputs the oscillation signal to the associated antenna (hereinafter simply referred to as "antenna 100") among one or more antennas 100, and then radiates microwaves corresponding to the oscillation signal via the antenna 100. The antenna 100 radiates microwaves corresponding to the oscillation signal.

[0034] Note that this embodiment has a configuration in which one or more signal output devices 1 are associated with one or more antennas 100 on a one-to-one basis. However, this should not be construed as a limitation. Alternatively, a configuration may also be adopted in which some or all of the outputs of a plurality of signal output devices 1 are combined together to be connected to an antenna 100 that is smaller in number than the signal output devices 1. Alternatively, a configuration may also be adopted in which the outputs of one or more signal output devices 1 are distributed and connected to an antenna 100 that is greater in number than the signal output devices 1. Alternatively, a configuration may also be adopted in which a switch is provided at the contact point between each signal output device 1 and a corresponding one of the antennas 100 so that the antenna to which any one of the signal output devices 1 is connected is selectable.

[0035] In addition, as described above, it is not necessary to provide the antenna 100. Alternatively, a configuration may also be adopted in which an oscillation signal is output to a waveguide to transmit microwaves, such that the microwaves are output to the storage container 3 through the waveguide.

[0036] As Figure 1 shown, the signal output device 1 according to the first embodiment includes an oscillator 20, a frequency detection unit 30, a first phase shifter 40, and a phase control unit 50. The signal output device 1 further includes a plurality of (e.g., two in the Figure 1 illustrated example) temperature sensors 60, a temperature monitoring unit 61, and an output terminal 70 electrically connected to the antenna 100.

[0037] As Figure 1 shown, the oscillator 20 includes a plurality of (e.g., two in the Figure 1 illustrated example) amplifiers 21, a second phase shifter 22, a third phase shifter 23, a feedback control unit 24, a distributor 25, and a combiner 26. That is, the oscillator 20 is a feedback oscillator and outputs an oscillation signal.

[0038] The plurality of amplifiers 21 are connected in parallel. The plurality of amplifiers 21 amplify the oscillation signal and output the thus amplified oscillation signal to the antenna 100 electrically connected to the amplifiers 21. Note that if it is necessary to distinguish the plurality of amplifiers 21 from each other, the plurality of amplifiers 21 will be denoted by reference numerals 21a, 21b, etc.

[0039] The second phase shifter 22 is electrically connected to the input terminal of the amplifier 21b. Specifically, one end of the second phase shifter 22 is electrically connected to one of the distributed output terminals of the distributor 25. The other end of the second phase shifter 22 is electrically connected to the input terminal of the amplifier 21b. The second phase shifter 22 shifts the phase of the oscillation signal supplied to the amplifier 21b. Thus, the amplifier 21b receives a feedback signal whose phase has been shifted.

[0040] The third phase shifter 23 is electrically connected to the output terminal of the amplifier 21a. Specifically, one end of the third phase shifter 23 is electrically connected to the output terminal of the amplifier 21a. The other end of the third phase shifter 23 is electrically connected to one of the input terminals at one end of the combiner 26 and the output terminal of the amplifier 21b. The third phase shifter 23 shifts the phase of the oscillation signal output from the amplifier 21a.

[0041] In this circuit configuration, the magnitude of the phase shift of the feedback signal caused by the second phase shifter 22 is equal to the magnitude of the phase shift of the feedback signal caused by the third phase shifter 23.

[0042] The combiner 26 generates an oscillation signal by combining the feedback signal output from the amplifier 21b and the feedback signal whose phase has been shifted by the third phase shifter 23, and outputs the thus generated oscillation signal to the frequency detection unit 30. The combiner 26 further generates a feedback signal by extracting a part of the oscillation signal thus combined, and outputs the thus generated feedback signal to the feedback control unit 24. That is, the oscillator 20 causes feedback signals having different phases from each other to pass through a plurality of amplifiers 21. Then, the oscillator 20 combines the feedback signals that have respectively passed through the plurality of amplifiers 21 to output an oscillation signal.

[0043] The amplifier 21a receives the feedback signal whose phase has not been shifted. The amplifier 21a amplifies the thus received feedback signal to output the thus amplified feedback signal. The third phase shifter 23 receives the feedback signal output from the amplifier 21a. The third phase shifter 23 shifts the phase of the thus received feedback signal. The amplifier 21b receives the feedback signal whose phase has been shifted by the second phase shifter 22. The amplifier 21b amplifies the feedback signal thus received from the second phase shifter 22 (i.e., the feedback signal whose phase has been shifted), to output the amplified feedback signal. That is, the phase of the feedback signal input to the amplifier 21a and the feedback signal output from the amplifier 21a is different from the phase of the feedback signal input to the amplifier 21b and the feedback signal output from the amplifier 21b. In addition, the magnitude of the phase shift of the feedback signal caused by the second phase shifter 22 is equal to the magnitude of the phase shift of the feedback signal caused by the third phase shifter 23. Therefore, the phase of the feedback signal output from the amplifier 21b matches the phase of the feedback signal that has been shifted by the third phase shifter 23.

[0044] The feedback control unit 24 performs feedback control by causing the combiner 26 to extract a part of the oscillation signal, which is generated by combining the feedback signal amplified by the amplifier 21a and the feedback signal amplified by the amplifier 21b. Specifically, the feedback control unit 24 performs frequency control to control the frequency and phase of the radiated microwave toward their respective target values. The feedback control unit 24 outputs a feedback signal to the plurality of amplifiers 21 by performing feedback control on the plurality of amplifiers 21.

[0045] The distributor 25 distributes the feedback signal output from the feedback control unit 24 to the amplifier 21a and the second phase shifter 22.

[0046] The combiner 26 of the oscillator 20 outputs the oscillation signal generated by combining the feedback signal amplified by the amplifier 21a and the feedback signal amplified by the amplifier 21b to the frequency detection unit 30. The combiner 26 further generates a feedback signal by extracting a part of the oscillation signal combined in this way, and outputs the feedback signal generated in this way to the feedback control unit 24.

[0047] The frequency detection unit 30 detects the frequency of the oscillation signal output from the oscillator 20. That is, the frequency detection unit 30 detects the frequency of the oscillation signal combined in this way. The frequency detection unit 30 outputs the detection result (that is, the frequency of the oscillation signal combined in this way) to the phase control unit 50. The frequency detection unit 30 further outputs the oscillation signal combined in this way to the first phase shifter 40.

[0048] The phase control unit 50 controls the first phase shifter 40 so that the first phase shifter 40 changes the load impedance of the oscillator 20. That is, the phase control unit 50 controls the first phase shifter 40 so that the first phase shifter 40 changes the load impedance of the oscillator 20 according to the oscillation frequency of the oscillation signal. Specifically, the phase control unit 50 controls the first phase shifter 40 so that the first phase shifter 40 shifts the phase of the oscillation signal according to the frequency of the oscillation signal detected by the frequency detection unit 30. The phase control unit 50 causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency detected by the frequency detection unit 30. The impedance characteristics of the antenna change according to the frequency of the radiated microwave. The phase control unit 50 causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency detected by the frequency detection unit 30 so that the impedance of the antenna falls within an appropriate range. That is, the phase control unit 50 shifts the phase of the oscillation signal by controlling the first phase shifter 40 based on the frequency detected by the frequency detection unit 30, so that the impedance of the antenna falls within an appropriate range.

[0049] When a variety of edible and drinkable products are stored in the storage container 3, the impedance of the antenna falls within a specific range on the Smith chart according to the frequency. For example,Figure 3 The impedance characteristics of the antenna at a frequency of 2.4 GHz to 2.5 GHz are shown in the figure. Figure 3 The range L1 shown is the range within which the impedance of the antenna falls when a signal with a frequency of 2.4 GHz is output. Figure 3 The range L2 shown is the range within which the impedance of the antenna falls when a signal with a frequency of 2.43 GHz is output. Figure 3 The range L3 shown is the range within which the impedance of the antenna falls when a signal with a frequency of 2.45 GHz is output. Figure 3 The range L4 shown is the range within which the impedance of the antenna falls when a signal with a frequency of 2.47 GHz is output. Figure 3 The range L5 shown is the range within which the antenna's impedance falls when outputting a signal with a frequency of 2.5 GHz. It can be seen that the antenna's impedance characteristics vary depending on the frequency of the radiated microwaves. Therefore, as described above, the phase control unit 50 causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency of the oscillation signal, thereby allowing the antenna's impedance to fall within an appropriate range. This allows for the radiation of microwaves appropriate to the frequency of the oscillation signal.

[0050] For example, the phase control unit 50 determines the phase shift amplitude according to the frequency of the oscillation signal detected by the frequency detection unit 30 by referring to a table in which phase shift amplitudes associated with a plurality of frequencies are pre-stored on a one-to-one basis. The phase control unit 50 shifts the phase of the oscillation signal by controlling the first phase shifter 40 based on the phase shift amplitude thus determined.

[0051] The first phase shifter 40 is provided at the output of the oscillator 20 to change the load impedance of the antenna 100 as viewed from the oscillator 20. Specifically, under the control of the phase control unit 50, the first phase shifter 40 changes the load impedance of the antenna 100 as viewed from the oscillator 20 according to the frequency detected by the frequency detection unit 30, thereby allowing the impedance of the antenna 100 to fall within an appropriate range. The first phase shifter 40 is electrically connected to the output terminal 70. The oscillation signal that has passed through the first phase shifter 40 is radiated as microwaves via the antenna 100 electrically connected to the output terminal 70.

[0052] The plurality of temperature sensors 60 respectively detect the temperatures of the plurality of amplifiers 21. The plurality of temperature sensors 60 are associated one-to-one with the plurality of amplifiers 21, and each temperature sensor detects the temperature of an associated one of the plurality of amplifiers 21. Each of the plurality of temperature sensors 60 outputs a detection result regarding the associated one of the plurality of amplifiers 21 (i.e., the temperature of the associated one of the amplifiers 21) to the temperature monitoring unit 61.

[0053] The temperature monitoring unit 61 receives the detection results from each of the plurality of temperature sensors 60. The function of generating an oscillation signal using the oscillator 20 is controlled based on each of the detection results received by the temperature monitoring unit 61. For example, at least one of frequency control, phase control, or amplitude control of the oscillation signal is controlled based on the plurality of detection results received by the temperature monitoring unit 61. Specifically, in the case where all of the plurality of detected temperatures are equal to or higher than the first threshold, the signal generation unit 10 is controlled to stop radiating microwaves. In the case where at least one of the plurality of detected temperatures is lower than the first threshold and equal to or higher than the second threshold, at least one of frequency control, phase control, or amplitude control of the microwaves to be radiated is controlled. For example, in the case of performing frequency control, the signal generation unit 10 is controlled to change the frequency of the microwaves from a first frequency to a second frequency. As used herein, the second frequency is lower than the first frequency. In the case of performing phase control, for example, by injection locking, the phase of the radiated microwaves is synchronized with the phase of an external reference signal. Further, in the case of performing amplitude control, the power supply voltage is controlled to reduce the amplitude of the radiated microwaves. In the case where all of the plurality of detected temperatures are lower than the second threshold, the control of the signal generation unit 10 is not performed.

[0054] Note that the control based on the detection results obtained by the temperature sensors 60 may also be performed by the signal output device 1, the feedback control unit 24, or an external device.

[0055] The output terminal 70 is provided between the first phase shifter 40 and the antenna 100. The output terminal 70 is electrically connected to each of the first phase shifter 40 and the antenna 100. The output terminal 70 outputs the oscillation signal (i.e., microwaves) supplied from the first phase shifter 40 to the antenna 100.

[0056] (3) Operation

[0057] Next, an exemplary operation of the signal output device 1 will be described.

[0058] The oscillator 20 causes a plurality of feedback signals having different phases from each other to pass through the plurality of amplifiers 21. Then, the oscillator 20 combines the feedback signals that have respectively passed through the plurality of amplifiers 21 to generate an oscillation signal.

[0059] The frequency detection unit 30 detects the frequency of the oscillation signal output by the oscillator 20. The phase control unit 50 causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency detected by the frequency detection unit 30, thereby allowing the impedance of the antenna to fall within an appropriate range. The first phase shifter 40 shifts the phase of the oscillation signal under the control of the phase control unit 50.

[0060] The oscillation signal whose phase has been shifted by the first phase shifter 40 is radiated into the interior of the storage container 3 as microwaves from the antenna 100 .

[0061] Furthermore, antenna 100 receives reflected waves of the radiated microwaves. The reflected waves are received, and a reflection signal representing the received reflected waves is supplied to each of the plurality of amplifiers 21. This causes the temperature of each of the plurality of amplifiers 21 to rise. Therefore, each of the plurality of temperature sensors 60 detects the temperature of its associated amplifier 21, and temperature monitoring unit 61 monitors the resulting temperature.

[0062] Even if there is no reflected wave, when the temperature of the signal output device 1 rises due to, for example, a decrease in the cooling performance of the cooling mechanism of the signal output device 1, each of the plurality of temperature sensors 60 detects the temperature of the amplifier 21 associated therewith. The temperature monitoring unit 61 monitors the result obtained thereby.

[0063] The function of generating an oscillation signal using the signal generating unit 10 is controlled based on each of the temperatures of the plurality of amplifiers 21 monitored by the temperature monitoring unit 61 (ie, the detection result (ie, detected temperature) obtained by an associated one of the temperature sensors 60 ).

[0064] (4) Advantages

[0065] As can be seen from the foregoing description, the signal output device 1 according to the first embodiment outputs an oscillation signal for generating microwaves for irradiating edibles and drinkables. The signal output device 1 includes an oscillator 20 that generates the oscillation signal, a phase shifter (i.e., a first phase shifter 40), and a phase control unit 50. The oscillator 20 outputs the oscillation signal to an antenna that radiates microwaves. The phase shifter is provided at the output position of the oscillator 20 to change the load impedance of the antenna 100 as viewed from the oscillator 20. The phase control unit 50 causes the phase shifter to control the load impedance of the oscillator 20 according to the oscillation frequency of the oscillation signal.

[0066] This configuration allows appropriate microwaves to be radiated according to the frequency of the oscillation signal. Therefore, this configuration contributes to improved performance even when edible and drinkable products are irradiated with microwaves.

[0067] Furthermore, in the signal output device 1, the oscillator 20 includes: a plurality of amplifiers 21 connected in parallel; and a feedback control unit 24 for performing feedback control on the signal generating unit 10. The oscillator 20 passes oscillation signals having different phases from each other through the plurality of amplifiers 21. The oscillator 20 then combines the feedback signals that have passed through the plurality of amplifiers 21 to generate an oscillation signal.

[0068] Figure 4 A shows the load characteristics of the oscillation signal frequency when observing the output position of the antenna 100 (e.g., inside the storage container 3) from the multiple amplifiers 21 in the signal output device 1. Figure 4 B shows the load characteristics of the output power when observing the output position of the antenna 100 (e.g., inside the storage container 3) from the multiple amplifiers 21 in the signal output device 1. That is, Figure 4 A and Figure 4 B respectively show the load characteristics of the frequency and the load characteristics of the output power when oscillation signals with different phases from each other pass through the multiple amplifiers 21 and the output position of the antenna 100 is observed from the multiple amplifiers 21 in the signal output device 1. Figure 4 The range L10 shown in A is the range of the oscillation frequency available for impedance with respect to the load characteristics when oscillation signals with different phases from each other pass through the multiple amplifiers 21 and the output position of the antenna 100 is observed from the oscillator 20 in the signal output device 1. Figure 4 The range L11 shown in B is the range of the output power available for impedance with respect to the load characteristics when feedback signals with different phases from each other pass through the multiple amplifiers 21 and the output position of the antenna 100 is observed from the oscillator 20 in the signal output device 1.

[0069] In addition, Figure 5 The range L20 shown in A is the range of the oscillation frequency available for impedance with respect to the load characteristics when oscillation signals with the same phase pass through the multiple amplifiers in a signal output device (hereinafter referred to as the signal output device according to the comparative example) connected in parallel. Figure 5 The range L21 shown in B is the range of the output power available for impedance with respect to the load characteristics when oscillation signals with the same phase pass through the multiple amplifiers in the signal output device according to the comparative example.

[0070] From Figure 4 A and Figure 5 A, it can be seen that the range L10 representing the load characteristics corresponding to the oscillation frequency available for the oscillator 20 in the signal output device 1 is wider than the range L20 representing the load characteristics corresponding to the oscillation frequency available for the oscillator 20 in the signal output device according to the comparative example. Similarly, as can be seen in Figure 4 B and Figure 5 B, the range L11 representing the load characteristics corresponding to the output power available for the oscillator 20 in the signal output device 1 is wider than the range L21 representing the load characteristics corresponding to the output power available for the oscillator 20 in the signal output device according to the comparative example.

[0071] Therefore, passing such oscillation signals having different phases from each other through a plurality of amplifiers 21 allows widening the impedance range of the load characteristics corresponding to the available oscillation frequencies and the impedance range of the load characteristics corresponding to the available output power.

[0072] (5) Variations

[0073] Next, the variations will be listed one by one. Note that the variations described below can be appropriately adopted in combination with the first embodiment.

[0074] (5.1) First variation

[0075] In the first embodiment, the antenna 100 is not a component of the signal output device 1. However, this should not be construed as a limitation. Alternatively, the signal output device 1 may also include the antenna 100 as one of its components.

[0076] (5.2) Second variation

[0077] In the first embodiment, the oscillator 20 has a configuration in which a plurality of amplifiers 21 are connected in parallel. However, this is not the only configuration.

[0078] Alternatively, the oscillator 20 may also include only one amplifier 21 as one of its components. In this case, the signal output device 1 includes only one temperature sensor 60. The temperature sensor 60 detects the temperature of one amplifier 21 included in the oscillator 20. In addition, the frequency detection unit 30 detects the frequency of the oscillation signal output by the oscillator 20 including one amplifier 21. The phase control unit 50 controls the first phase shifter 40 so that the first phase shifter 40 shifts the phase of the oscillation signal according to the frequency thus detected.

[0079] (5.3) Third variation

[0080] The oscillator 20 may also have a configuration in which the distributor 25 for distributing the feedback signal to the plurality of amplifiers 21 is responsible for part or all of the phase shift amplitude caused by the second phase shifter 22. Additionally, the oscillator 20 may also have a configuration in which the combiner 26 for combining the output signals of the plurality of amplifiers 21 is responsible for part or all of the phase shift amplitude caused by the third phase shifter 23.

[0081] (5.4) Fourth variation

[0082] In the first embodiment, the oscillator 20 has a configuration in which oscillation signals having different phases from each other pass through a plurality of amplifiers 21. However, this should not be construed as a limitation. Alternatively, the oscillator 20 may also pass oscillation signals having different phases from each other through at least two of the plurality of amplifiers 21.

[0083] (5.5) Fifth variant

[0084] In the first embodiment, the first phase shifter 40 changes the load impedance of the antenna 100 as observed from the oscillator 20. However, this should not be construed as a limitation. Alternatively, the first phase shifter 40 can not only change the phase but also change the impedance.

[0085] (Second embodiment)

[0086] In the second embodiment, the oscillator is an amplifier-type oscillator. This is different from the first embodiment in which the oscillator is a feedback oscillator.

[0087] Next, the configuration of the signal output device 1A according to the second embodiment will be described. The following description will focus on the differences from the first embodiment. Note that any component of the second embodiment having the same configuration as the corresponding part of the first embodiment will be denoted by the same reference numeral as that corresponding part, and its description will be appropriately omitted here.

[0088] As in the first embodiment, the signal output device 1A according to the second embodiment is applied to the electrical device 2. In this case, the electrical device 2 to which the signal output device 1A is applied can be, for example, a microwave oven, a refrigerator, or a freezer. That is, the electrical device 2 according to the second embodiment includes the signal output device 1A and the storage container 3.

[0089] As Figure 6 shown, the signal output device 1A according to the second embodiment includes a signal generator 80, an oscillator 20A, a first phase shifter 40, and a phase control unit 50A. The signal output device 1A further includes a plurality of (for example, two in the Figure 6 illustrated example) temperature sensors 60, a temperature monitoring unit 61, and an output terminal 70 electrically connected to the antenna 100 (refer to Figure 2 ).

[0090] The signal generator 80 includes a signal generation unit 10A and a frequency detection unit 30A.

[0091] The signal generation unit 10A is a semiconductor microwave oscillator and controls the frequency to generate (i.e., oscillate) an oscillation signal that will form the basis of a microwave having a predetermined frequency. The signal generation unit 10A performs phase control. The signal generation unit 10A includes, for example, a quadrature modulation circuit and shifts the phase of the oscillation signal. The signal output device 1A further performs gain control of the oscillation signal, that is, amplitude control. The signal generation unit 10A performs gain adjustment on the oscillation signal.

[0092] The frequency detection unit 30A detects the frequency of the oscillation signal generated by the signal generation unit 10A.

[0093] The oscillator 20A includes, for example, a power amplifier 200.

[0094] The power amplifier 200 amplifies an oscillation signal and outputs the thus amplified oscillation signal to an antenna 100 electrically connected to the power amplifier 200. The power amplifier 200 includes a device group 201 composed of a plurality of devices, a final-stage device 202, a distributor 25, and a combiner 26A. The plurality of devices included in the device group 201 and the final-stage device 202 are, for example, transistors. The device 202 is sometimes hereinafter referred to as the "final-stage device 202". The oscillator 20A (i.e., the power amplifier 200) according to the second embodiment includes the plurality of devices included in the device group 201 and the final-stage device 202. That is, the oscillator 20A is a so-called "amplifier-type oscillator" for amplifying an oscillation signal generated by a signal generator 80 through an amplifier.

[0095] The device group 201 is electrically connected to the signal generation unit 10A. The device group 201 is electrically connected to the final-stage device 202. The distributor 25 distributes the oscillation signal output from the device group 201 to an amplifier 21a and a second phase shifter 22. The final-stage device 202 is electrically connected to an output terminal 70. That is, the final-stage device 202 is electrically connected to the antenna 100. The final-stage device 202 outputs an oscillation signal (i.e., a microwave) to the antenna 100 via the output terminal 70.

[0096] As Figure 6 shown, the final-stage device 202 includes a plurality of (for example, two in the Figure 6 illustrated example) amplifiers 211 connected in parallel. Note that if the plurality of amplifiers 211 need to be distinguished from each other, the plurality of amplifiers 211 will hereinafter be denoted by reference numerals 211a, 211b, etc.

[0097] The combiner 26A of the oscillator 20A (i.e., the power amplifier 200) combines the oscillation signal output from the amplifier 211b and the oscillation signal whose phase has been shifted by a third phase shifter 23. Specifically, two oscillation signals having different phases from each other respectively pass through the plurality of amplifiers 211. Then, the combiner 26A combines the oscillation signals that have respectively passed through the plurality of amplifiers 211.

[0098] The amplifier 211a receives an oscillation signal whose phase is not shifted. The amplifier 211a amplifies the oscillation signal thus received to output the amplified oscillation signal. The third phase shifter 23 receives the oscillation signal output from the amplifier 211a. The third phase shifter 23 shifts the phase of the oscillation signal thus received. The amplifier 21b receives the oscillation signal whose phase has been shifted by the second phase shifter 22. The amplifier 21b amplifies the oscillation signal thus received (i.e., the oscillation signal whose phase has been shifted), to output the amplified oscillation signal. That is, the phase of the oscillation signal input to the amplifier 21a and output from this amplifier is different from the phase of the oscillation signal input to the amplifier 21b and output from this amplifier. In addition, the amplitude of the shift in the phase of the oscillation signal caused by the second phase shifter 22 is equal to the amplitude of the shift in the phase of the oscillation signal caused by the third phase shifter 23. Therefore, the phase of the oscillation signal output from the amplifier 211b matches the phase of the oscillation signal whose phase has been shifted by the third phase shifter 23.

[0099] The oscillator 20A outputs an oscillation signal generated by combining the oscillation signal amplified by the amplifier 211a and the oscillation signal amplified by the amplifier 211b to the first phase shifter 40.

[0100] The phase control unit 50A controls the first phase shifter 40 to cause the first phase shifter 40 to change the load impedance of the oscillator 20. More specifically, the phase control unit 50A controls the first phase shifter 40 to cause the first phase shifter 40 to change the load impedance of the oscillator 20 according to the oscillation frequency of the oscillation signal. For example, the phase control unit 50A controls the first phase shifter 40 to cause the first phase shifter 40 to shift the phase of the oscillation signal according to the frequency of the oscillation signal detected by the frequency detection unit 30A. The phase control unit 50A causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency detected by the frequency detection unit 30A. The impedance characteristics of the antenna 100 observed from the oscillator 20A change according to the radiated microwave frequency. The phase control unit 50 causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency detected by the frequency detection unit 30A, thereby allowing the impedance of the antenna 100 to fall within an appropriate range. That is, the phase control unit 50A controls the first phase shifter 40 to cause the first phase shifter 40 to change the load impedance of the antenna 100 observed from the oscillator 20A based on the frequency detected by the frequency detection unit 30A, thereby allowing the impedance of the antenna 100 to fall within an appropriate range.

[0101] A plurality of temperature sensors 60 respectively detect the temperatures of a plurality of amplifiers 211. The plurality of temperature sensors 60 are associated with the plurality of amplifiers 211 one-to-one, and each temperature sensor detects the temperature of an associated one of the plurality of amplifiers 211. Each temperature sensor among the plurality of temperature sensors 60 outputs a detection result regarding an associated one of the plurality of amplifiers 211 (i.e., the temperature of the associated one of the amplifiers 21) to the temperature monitoring unit 61.

[0102] The temperature monitoring unit 61 receives the detection results from each of the plurality of temperature sensors 60. The function of generating an oscillation signal using the signal generation unit 10A is controlled based on the corresponding detection results received by the temperature monitoring unit 61. For example, based on the plurality of detection results received by the temperature monitoring unit 61, at least one of frequency control, phase control, or amplitude control of the oscillation signal is performed.

[0103] Note that the control of the signal generation unit 10A based on the detection results obtained by the temperature sensor 60 can be performed by the signal output device 1A or an external device, depending on the situation.

[0104] Next, an exemplary operation of the signal output device 1A will be described.

[0105] The signal generation unit 10A generates an oscillation signal having a predetermined frequency to radiate microwaves having a predetermined frequency. The signal generation unit 10A generates an oscillation signal having a predetermined frequency to perform, for example, gain adjustment on the oscillation signal so generated. In this case, the frequency detection unit 30A detects the frequency of the oscillation signal so generated.

[0106] The oscillator 20A (i.e., the power amplifier 200) causes the device group 201 and the final-stage device 202 to amplify the oscillation signal. In this case, the final-stage device 202 causes oscillation signals having different phases from each other to pass through the plurality of amplifiers 211. Then, the final-stage device 202 combines the oscillation signals that have respectively passed through the plurality of amplifiers 21.

[0107] The phase control unit 50A causes the first phase shifter 40 to modulate the frequency of the oscillation signal based on the frequency detected by the frequency detection unit 30A, thereby allowing the impedance of the antenna 100 to fall within an appropriate range. The first phase shifter 40 changes the load impedance of the antenna 100 as observed from the oscillator 20A under the control of the phase control unit 50A.

[0108] The oscillation signal whose phase has been shifted by the first phase shifter 40 is radiated as microwaves from the antenna 100 into the storage container 3.

[0109] In addition, the antenna 100 receives the reflected wave of the radiated microwave. The reflected wave is received, and a reflected signal representing the received reflected wave is supplied to each of the plurality of amplifiers 211 of the final-stage device 202. This causes the temperature of each of the plurality of amplifiers 211 to rise. Accordingly, each of the plurality of temperature sensors 60 detects the temperature of an associated one of the plurality of amplifiers 211, and the temperature monitoring unit 61 monitors the results thus obtained.

[0110] Even without the reflected wave, when the temperature of the signal output device 1A rises due to, for example, a decline in the cooling performance of the cooling mechanism of the signal output device 1A, each of the plurality of temperature sensors 60 detects the temperature of an associated one of the plurality of amplifiers 211. The temperature monitoring unit 61 monitors the results thus obtained.

[0111] Based on the temperatures of the plurality of amplifiers 211 monitored by the temperature monitoring unit 61 (i.e., the detection results (i.e., the detected temperatures) obtained by the temperature sensors 60), the function of generating an oscillation signal using the signal generation unit 10A is controlled.

[0112] As in the first embodiment, the signal output device 1A according to the second embodiment allows appropriate microwaves to be radiated according to the frequency of the oscillation signal. Thus, this configuration helps to improve performance even when irradiating edible and drinkable products with microwaves.

[0113] The signal output device 1A also causes such oscillation signals having different phases from each other to pass through the plurality of amplifiers 211, thereby allowing the impedance range of the load characteristics corresponding to the frequency and the impedance range of the load characteristics corresponding to the output power to be widened.

[0114] Note that in the second embodiment, the oscillator 20A (i.e., the power amplifier 200) may further include a matching circuit provided between the signal generation unit 10A and the device group 201 for matching the impedance between the signal generation unit 10A and the device group 201. Alternatively, the oscillator 20A (i.e., the power amplifier 200) may further include a matching circuit provided between the device group 201 and the final-stage device 202 for matching the impedance between the device group 201 and the final-stage device 202. Still alternatively, the oscillator 20A (i.e., the power amplifier 200) may further include a matching circuit provided between the first phase shifter 40 and the output terminal 70 for matching the impedance between the first phase shifter 40 and the constituent elements (such as the output terminal 70 and the antenna 100) connected to the output terminal at the stage after the output terminal 70.

[0115] In addition, in the second embodiment, the oscillator 20A has a configuration in which oscillation signals having different phases from each other pass through two amplifiers 211. However, this should not be construed as a limitation. Alternatively, the oscillator 20A may also cause oscillation signals having different phases from each other to pass through at least two of three or more amplifiers 211. The oscillator 20A may also have a configuration in which a distributor 25 for distributing the oscillation signal to the plurality of amplifiers 211 is responsible for part or all of the phase shift amplitude caused by the second phase shifter 22. In addition, the oscillator 20A may also have a configuration in which a combiner 26A for combining the output signals of the plurality of amplifiers 211 is responsible for part or all of the phase shift amplitude caused by the third phase shifter 23.

[0116] In addition, the first and second variants of the first embodiment can also be applied to the second embodiment.

[0117] (General summary)

[0118] As can be seen from the foregoing description, the signal output device (1; 1A) according to the first aspect outputs an oscillation signal for generating microwaves to irradiate edible and drinkable products. The signal output device (1; 1A) includes an oscillator (20; 20A), a phase shifter (e.g., the first phase shifter 40), and a phase control unit (50; 50A). The oscillator (20; 20A) outputs an oscillation signal to an antenna (100) that radiates microwaves. The phase shifter is provided at the output position of the oscillator (20; 20A) to change the load impedance of the antenna (100) as observed from the oscillator (20; 20A). The phase control unit (50; 50A) controls the phase shifter so that the phase shifter changes the load impedance of the oscillator (20; 20A) according to the oscillation frequency of the oscillation signal.

[0119] This aspect allows for the radiation of appropriate microwaves according to the frequency of the oscillation signal. Therefore, this aspect helps to improve performance even when irradiating edible and drinkable products with microwaves.

[0120] In the signal output device (1A) according to the second aspect that can be implemented in combination with the first aspect, the oscillator (20A) includes a power amplifier (200). The power amplifier (200) includes a final stage device (202), and the final stage device includes a plurality of amplifiers (211) connected in parallel. The power amplifier (200) causes a plurality of oscillation signals having different phases from each other to pass through the plurality of amplifiers (211), and combines the plurality of oscillation signals that have respectively passed through the plurality of amplifiers (211).

[0121] This aspect allows for widening the impedance range of the load characteristics corresponding to the available frequency and the impedance range of the load characteristics corresponding to the available output power.

[0122] In the signal output device (1) according to the third aspect, which can be implemented in combination with the first aspect, the oscillator (20) includes a plurality of amplifiers (21) connected in parallel and a feedback control unit (24). The feedback control unit (24) outputs a feedback signal to the plurality of amplifiers (21) by performing feedback control on the plurality of amplifiers (21). The oscillator (20) causes a plurality of feedback signals having different phases from each other to pass through the plurality of amplifiers (21), and combines the plurality of feedback signals that have respectively passed through the plurality of amplifiers (21), thereby generating an oscillation signal.

[0123] This aspect allows widening the impedance range of the load characteristics corresponding to the available frequency and the impedance range of the load characteristics corresponding to the available output power.

[0124] The signal output device (1; 1A) according to the fourth aspect, which can be implemented in combination with the first aspect, further includes a temperature sensor (60). The oscillator (20; 20A) includes an amplifier (21; 211). The temperature sensor (60) detects the temperature of the amplifier (21).

[0125] According to this aspect, monitoring the temperature of the amplifier (21) allows more precise control of microwave radiation, that is, the output of the oscillation signal.

[0126] The signal output device (1; 1A) according to the fifth aspect, which can be implemented in combination with the second aspect or the third aspect, further includes a plurality of temperature sensors (60) for respectively detecting the temperatures of the plurality of amplifiers (21; 211).

[0127] According to this aspect, monitoring the temperatures of the plurality of amplifiers (21) allows more precise control of microwave radiation, that is, the output of the oscillation signal.

[0128] The signal output device (1; 1A) according to the sixth aspect, which can be implemented in combination with any one of the first aspect to the fifth aspect, further includes a frequency detection unit (30; 30a). The frequency detection unit (30; 30A) detects the frequency of the oscillation signal output by the oscillator (20; 20A). The phase control unit (50) controls the phase shifter to cause the phase shifter to shift the phase of the oscillation signal according to the frequency detected by the frequency detection unit (30; 30A).

[0129] This aspect allows radiating appropriate microwaves according to the frequency of the oscillation signal.

[0130] The microwave oven (2a) according to the seventh aspect includes a signal output device (1; 1A) according to any one of the first to sixth aspects and a storage container (3). The storage container (3) stores an object to be irradiated with microwaves, and the microwaves are radiated from the signal output device (1; 1A) via the antenna (100).

[0131] This aspect helps to improve performance even when irradiating edible and drinkable items with microwaves.

[0132] The refrigerator according to the eighth aspect includes a signal output device (1; 1A) according to any one of the first to sixth aspects and a storage container (3). The storage container (3) stores an object to be irradiated with microwaves, and the microwaves are radiated from the signal output device (1; 1A) via the antenna (100).

[0133] This aspect helps to improve performance even when irradiating edible and drinkable items with microwaves.

[0134] The freezer according to the ninth aspect includes a signal output device (1; 1A) according to any one of the first to sixth aspects and a storage container (3). The storage container (3) stores an object to be irradiated with microwaves, and the microwaves are radiated from the signal output device (1; 1A) via the antenna (100).

[0135] This aspect helps to improve performance even when irradiating edible and drinkable items with microwaves.

[0136] List of Reference Numerals

[0137] 1, 1A Signal output device

[0138] 2 Electrical device

[0139] 2a Microwave oven

[0140] 3 Storage container

[0141] 20, 20A Oscillator

[0142] 21, 21a, 21b Amplifier

[0143] 24 Feedback control unit

[0144] 25 Distributor

[0145] 26, 26A Combiner

[0146] 30, 30A Frequency detection unit

[0147] 40 First phase shifter (phase shifter)

[0148] 50, 50A Phase control unit

[0149] 60 Temperature sensor

[0150] 100 Antenna

[0151] 200 Power amplifier

[0152] Amplifiers 211, 211a, 211b

[0153] 202 Final stage device (device)

Claims

1. A signal output device configured to output an oscillation signal for generating microwaves to irradiate edible and drinkable products, the signal output device comprising: An oscillator configured to output the oscillation signal to an antenna configured to radiate the microwaves; A phase shifter provided at an output position of the oscillator to change a load impedance of the antenna as viewed from the oscillator; And A phase control unit configured to control the phase shifter to change the load impedance of the oscillator according to an oscillation frequency of the oscillation signal.

2. The signal output device according to claim 1, wherein The oscillator includes a power amplifier, The power amplifier includes a final stage device including a plurality of amplifiers connected in parallel, and The power amplifier is configured to cause a plurality of the oscillation signals having different phases from each other to pass through the plurality of amplifiers, and combine the plurality of oscillation signals that have respectively passed through the plurality of amplifiers.

3. The signal output device according to claim 1, wherein The oscillator includes: A plurality of amplifiers connected in parallel; and A feedback control unit configured to output a feedback signal to the plurality of amplifiers by performing feedback control on the plurality of amplifiers, and The oscillator is configured to cause a plurality of the feedback signals having different phases from each other to pass through the plurality of amplifiers, and combine the plurality of feedback signals that have respectively passed through the plurality of amplifiers to generate the oscillation signal.

4. The signal output device according to claim 1, the signal output device further comprising a temperature sensor, wherein The oscillator includes an amplifier, and The temperature sensor is configured to detect a temperature of the amplifier.

5. The signal output device according to claim 2 or 3, the signal output device further comprising a plurality of temperature sensors configured to respectively detect temperatures of the plurality of amplifiers.

6. The signal output device according to any one of claims 1 to 5, the signal output device further comprising a frequency detection unit configured to detect a frequency of the oscillation signal output by the oscillator, wherein The phase control unit is configured to control the phase shifter to shift a phase of the oscillation signal according to the frequency detected by the frequency detection unit.

7. A microwave oven comprising: The signal output device according to any one of claims 1 to 6; And A storage container configured to store an object to be a target irradiated with the microwaves, the microwaves being radiated from the signal output device via the antenna.

8. A refrigerator comprising: The signal output device according to any one of claims 1 to 6; And A storage container configured to store an object to be a target irradiated with microwaves, the microwaves being radiated from the signal output device via the antenna.

9. A refrigerator, comprising: The signal output device according to any one of claims 1 to 6; And A storage container configured to store an object to be a target irradiated with microwaves, the microwaves being radiated from the signal output device via the antenna.

Images