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 food and drink. A signal output device (1) outputs an oscillation signal for generating microwaves to be applied to food and drink. The signal output device (1) comprises: an oscillator (20); a phase shifter (e.g., first phase shifter 40); and a phase control unit (50). The oscillator (20) outputs the oscillation signal to an antenna through which the microwaves are applied. The phase shifter is provided to an output destination of the oscillator (20), and changes load impedance viewed from the oscillator (20) to the antenna. The phase control unit (50) controls the phase shifter so as to change the load impedance of the oscillator (20) in accordance with the oscillation frequency of the oscillation signal.

Description

Signal output device, microwave oven, refrigerator and freezer

[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, a microwave oven, a refrigerator, and a freezer that outputs an oscillation signal for generating microwaves to be irradiated onto food and drink.

[0002] 2. Description of the Related Art Conventionally, a transmitting device has been known that can eliminate an isolator and improve the performance of a portable radio (see, for example, Patent Document 1).

[0003] In the transmitting device of Patent Document 1, the signal output from the digital modulator is split into n parts, passes through n input phase shifters with different amounts of phase change, is amplified by n power amplifiers, passes through n output phase shifters to ensure that the phases of the n signals are aligned, is combined, and is output from the output terminal.

[0004] In Patent Document 1, the frequency of the signal output for use in wireless communication is predetermined. On the other hand, in an electrical device (e.g., a microwave oven) that irradiates food and drink with microwaves, the frequency of the irradiated microwaves can be changed. Therefore, it is difficult to apply the technology of Patent Document 1 to an electrical device that irradiates food and drink with microwaves.

[0005] Japanese Patent Application Publication No. 9-64758

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a signal output device, a microwave oven, a refrigerator, and a freezer that can achieve high performance even when microwaves are irradiated onto food and drink.

[0007] A signal output device according to one aspect of the present disclosure outputs an oscillation signal for generating microwaves to be irradiated onto food and drink. The signal output device includes an oscillator, a phase shifter, and a phase control unit. The oscillator outputs the oscillation signal to an antenna that irradiates the microwaves. The phase shifter is provided at the output destination of the oscillator and changes the load impedance of the antenna as seen from the oscillator. The phase control unit controls the phase shifter so that the phase shifter changes the load impedance of the oscillator in accordance with the oscillation frequency of the oscillation signal.

[0008] A microwave oven according to one aspect of the present disclosure includes the signal output device and a storage compartment for storing an object to be irradiated with the microwaves emitted from the signal output device via the antenna.

[0009] A refrigerator according to an aspect of the present disclosure includes the signal output device and a storage compartment. The storage compartment stores an object to be irradiated with the microwaves irradiated from the signal output device via the antenna.

[0010] A freezer according to one aspect of the present disclosure includes the signal output device and a storage compartment for storing an object to be irradiated with the microwaves emitted from the signal output device via the antenna.

[0011] FIG. 1 is a block diagram showing the configuration of a signal output device according to a first embodiment. FIG. 2 is a block diagram showing the configuration of an electrical device including the signal output device according to the first embodiment. FIG. 3 is a Smith chart showing the impedance characteristics of an antenna. FIG. 4A is a Smith chart showing the load impedance characteristics of the frequency of an oscillation signal output by the signal output device according to the first embodiment. FIG. 4B is a Smith chart showing the load impedance characteristics of the output power of an oscillation signal output by the signal output device according to the first embodiment. FIG. 5A is a Smith chart showing the load impedance characteristics of the frequency of an oscillation signal output by a signal output device of a comparative example. FIG. 5B is a Smith chart showing the load impedance characteristics of the output power of an oscillation signal output by a signal output device of a comparative example. FIG. 6 is a block diagram showing the configuration of a signal output device according to a second embodiment.

[0012] The embodiments and modifications described below are merely examples of the present disclosure, and the present disclosure is not limited to the following embodiments and modifications. Various modifications other than the following embodiments and modifications are possible depending on the design, etc., as long as they do not deviate from the technical concept of the present disclosure.

[0013] First Embodiment A signal output device 1 and an electrical device 2 according to a first embodiment will be described below with reference to FIGS. 1 to 5B.

[0014] (1) Overview A signal output device 1 according to a first embodiment irradiates a target object such as food or drink with high-power microwaves. For example, the signal output device 1 is applied to an electrical appliance 2. Here, the electrical appliance 2 is a microwave oven, a refrigerator, or a freezer. Fig. 2 shows a case where the signal output device 1 is applied to a microwave oven 2a as the electrical appliance 2. When the signal output device 1 is applied to the microwave oven 2a, the food or drink is heated by high-power microwaves.

[0015] A signal output device 1 according to the first embodiment outputs an oscillation signal for generating microwaves to be irradiated onto food and drink. The signal output device 1 outputs the oscillation signal to an electrically connected antenna 100 (see FIG. 2 ), and irradiates microwaves in accordance with the oscillation signal via the antenna 100. As shown in FIG. 1 , 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 (see FIG. 2 ), which irradiates microwaves. The first phase shifter 40 is provided at the output destination of the oscillator 20 and changes the load impedance seen from the oscillator 20 toward the antenna 100. 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 in accordance with the oscillation frequency of the oscillation signal.

[0016] This configuration allows for the irradiation of microwaves appropriate for the frequency of the oscillation signal, thereby achieving high performance even when irradiating microwaves onto food and drink.

[0017] (2) Configuration Here, the configurations of the electrical device 2 and the signal output device 1 according to the first embodiment will be described.

[0018] 2, the electrical device 2 includes a signal output device 1 and a storage compartment 3. The storage compartment 3 stores objects (food and drink) to be irradiated with microwaves emitted from the signal output device 1 via the antenna 100.

[0019] In the first embodiment, as shown in Fig. 2 , the electrical device 2 includes one or more (two in the illustrated example) signal output devices 1 and multiple (two in the illustrated example) antennas 100. The one or more antennas 100 are associated one-to-one with the one or more signal output devices 1. The electrical device 2 includes a storage 3. The storage 3 stores objects (food and drink) to be irradiated with microwaves irradiated from the signal output devices 1 via the antennas 100. Each antenna 100 is provided in the storage 3.

[0020] When the electrical appliance 2 is a microwave oven 2a, one or more signal output devices 1 heat the target to be irradiated (e.g., food or drink) stored in the storage facility 3 by irradiating the target with microwaves via the antenna 100.

[0021] In addition, when the electrical appliance 2 is a refrigerator, one or more signal output devices 1 irradiate a refrigerated object (food or drink) with microwaves via the antenna 100, thereby ripening the refrigerated object (food or drink). Furthermore, irradiating a sub-freezing object (food or drink) with microwaves via the antenna 100 causes the refrigerated object (food or drink) to be supercooled. Here, supercooling refers to a liquid, such as water, being cooled to a temperature lower than its freezing point (the temperature at which it freezes into a solid). For example, water normally freezes at temperatures below 0°C, but in a supercooled state, if certain conditions are met, it does not freeze even at temperatures below 0°C and continues to be cooled in liquid form.

[0022] Furthermore, when the electrical equipment 2 is a freezer, one or more signal output devices 1 irradiate microwaves via the antenna 100 onto an object (food or drink) that has been refrigerated below freezing, i.e., in a supercooled state, and by stopping the irradiation of microwaves, the object (food or drink) is instantly frozen.

[0023] The signal output device 1 according to the first embodiment generates an oscillation signal, outputs the oscillation signal to the antenna 100, and radiates microwaves corresponding to the oscillation signal via the antenna 100. The antenna 100 radiates microwaves corresponding to the oscillation signal.

[0024] In this embodiment, one or more signal output devices 1 and one or more antennas 100 are configured to correspond one-to-one, but the present invention is not limited to this configuration. A configuration may be adopted in which some or all of the outputs of multiple signal output devices 1 are combined and connected to fewer antennas 100 than the number of signal output devices 1. Alternatively, a configuration may be adopted in which the outputs of one or more signal output devices 1 are distributed and connected to more antennas 100 than the number of signal output devices 1. Furthermore, a configuration may be adopted in which a switch or the like is provided at the contact point between the signal output device 1 and the antenna 100, allowing the antenna to be connected to be selected.

[0025] Furthermore, as described above, the antenna 100 is not essential, and the configuration may be such that an oscillation signal is output to a waveguide to transmit microwaves, and the microwaves are output from the waveguide to the storage facility 3.

[0026] 1, 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 (two in the illustrated example) temperature sensors 60, a temperature monitoring unit 61, and an output terminal 70 electrically connected to the antenna 100.

[0027] 1, the oscillator 20 includes a plurality of (two in the 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. In other words, the oscillator 20 is a feedback type oscillator, and outputs an oscillation signal.

[0028] The multiple amplifiers 21 are connected in parallel. The multiple amplifiers 21 amplify the oscillation signal and output it to the electrically connected antenna 100. When it is necessary to distinguish between the multiple amplifiers 21, they will be referred to as amplifiers 21a and 21b.

[0029] 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 end of the distribution output of the distributor 25, and 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 changes the phase of the oscillation signal input to the amplifier 21b. Therefore, the amplifier 21b receives the feedback signal with the changed phase.

[0030] The third phase shifter 23 is electrically connected to the output terminal of the amplifier 21 a. Specifically, one end of the third phase shifter 23 is electrically connected to the output terminal of the amplifier 21 a, and the other end of the third phase shifter 23 is electrically connected to one input of the combiner 26 and the output of the amplifier 21 b. The third phase shifter 23 changes the phase of the oscillation signal output from the amplifier 21 a.

[0031] Here, the amount by which the second phase shifter 22 changes the phase of the feedback signal is the same as the amount by which the third phase shifter 23 changes the phase of the feedback signal.

[0032] The combiner 26 combines the feedback signal output by the amplifier 21b with the feedback signal whose phase has been changed by the third phase shifter 23 to generate an oscillation signal, which is output to the frequency detection unit 30. Furthermore, the combiner 26 extracts a part of the combined oscillation signal to generate a feedback signal, which is output to the feedback control unit 24. That is, the oscillator 20 passes feedback signals having different phases from one another through the multiple amplifiers 21, combines the feedback signals that have passed through the multiple amplifiers 21, and outputs the oscillation signal.

[0033] The amplifier 21a receives a feedback signal whose phase has not been changed. The amplifier 21a amplifies the input feedback signal and outputs the amplified feedback signal. The third phase shifter 23 receives the feedback signal output from the amplifier 21a. The third phase shifter 23 changes the phase of the input feedback signal. The amplifier 21b receives a feedback signal whose phase has been changed by the second phase shifter 22. The amplifier 21b amplifies the input feedback signal (the feedback signal whose phase has been changed) and outputs the amplified feedback signal. In other words, the phase of the feedback signal input to and output from the amplifier 21a is different from the phase of the feedback signal input to and output from the amplifier 21b. Furthermore, because the amount by which the second phase shifter 22 changes the phase of the feedback signal is the same as the amount by which the third phase shifter 23 changes the phase of the feedback signal, the phase of the feedback signal output from the amplifier 21b is the same as the phase of the feedback signal changed by the third phase shifter 23.

[0034] The feedback control unit 24 extracts a part of the oscillation signal obtained by combining the feedback signal amplified by the amplifier 21 a and the feedback signal amplified by the amplifier 21 b using a combiner 26, and performs feedback control. Specifically, the feedback control unit 24 performs frequency control so that the frequency and phase of the irradiated microwaves reach their respective target values. The feedback control unit 24 outputs feedback signals to the multiple amplifiers 21 by feedback control of the multiple amplifiers 21.

[0035] The distributor 25 distributes the feedback signal output from the feedback control unit 24 to the amplifier 21 a and the second phase shifter 22 .

[0036] The combiner 26 of the oscillator 20 combines the feedback signal amplified by the amplifier 21a and the feedback signal amplified by the amplifier 21b to generate an oscillation signal, and outputs the resulting signal to the frequency detection unit 30. Furthermore, the combiner 26 extracts a portion of the combined oscillation signal to generate a feedback signal, and outputs the feedback signal to the feedback control unit 24.

[0037] 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 combined oscillation signal. The frequency detection unit 30 outputs the detection result (the frequency of the combined oscillation signal) to the phase control unit 50. Furthermore, the frequency detection unit 30 outputs the combined oscillation signal to the first phase shifter 40.

[0038] 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 in accordance with 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 changes the phase of the oscillation signal in accordance with the frequency of the oscillation signal detected by the frequency detection unit 30. The phase control unit 50 varies the frequency of the oscillation signal using the first phase shifter 40 based on the frequency detected by the frequency detection unit 30. The impedance characteristics of the antenna differ depending on the frequency of the irradiated microwaves. Based on the frequency detected by the frequency detection unit 30, the phase control unit 50 varies the frequency of the oscillation signal using the first phase shifter 40 so that the antenna impedance falls within an appropriate range. That is, the phase control unit 50 controls the first phase shifter 40 to change the phase of the oscillation signal in accordance with the frequency detected by the frequency detection unit 30 so that the antenna impedance falls within an appropriate range.

[0039] When multiple foods and drinks are placed in storage 3, the antenna impedance falls within a certain range for each frequency on the Smith chart. For example, FIG. 3 shows the antenna impedance characteristics at frequencies between 2.4 GHz and 2.5 GHz. Region L1 shown in FIG. 3 indicates the range that includes the antenna impedance when a signal with a frequency of 2.4 GHz is output. Region L2 shown in FIG. 3 indicates the range that includes the antenna impedance when a signal with a frequency of 2.43 GHz is output. Region L3 shown in FIG. 3 indicates the range that includes the antenna impedance when a signal with a frequency of 2.45 GHz is output. Region L4 shown in FIG. 3 indicates the range that includes the antenna impedance when a signal with a frequency of 2.47 GHz is output. Region L5 shown in FIG. 3 indicates the range that includes the antenna impedance when a signal with a frequency of 2.5 GHz is output. In this way, the antenna impedance characteristics vary depending on the frequency of the irradiated microwaves. Therefore, as described above, the phase control unit 50 varies the frequency of the oscillation signal using the first phase shifter 40 based on the frequency of the oscillation signal so that the impedance of the antenna falls within an appropriate range, thereby enabling the irradiation of appropriate microwaves according to the frequency of the oscillation signal.

[0040] For example, based on a table that stores in advance a plurality of phase amounts that are associated one-to-one with a plurality of frequencies, the phase control unit 50 determines a phase amount corresponding to the frequency of the oscillation signal detected by the frequency detection unit 30. Based on the determined phase amount, the phase control unit 50 controls the first phase shifter 40 to change the phase of the oscillation signal.

[0041] The first phase shifter 40 is provided at the output destination of the oscillator 20 and changes the load impedance as seen from the oscillator 20 to the antenna 100. Specifically, under the control of the phase control unit 50, the first phase shifter 40 changes the load impedance as seen from the oscillator 20 to the antenna 100 based on the frequency detected by the frequency detection unit 30 so that the impedance of the antenna 100 falls 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 a microwave via the antenna 100 that is electrically connected to the output terminal 70.

[0042] The plurality of temperature sensors 60 detect the temperatures of the plurality of amplifiers 21, respectively. The plurality of temperature sensors 60 are associated one-to-one with the plurality of amplifiers 21, and detect the temperatures of the associated amplifiers 21. Each of the plurality of temperature sensors 60 outputs the detection result for the corresponding amplifier 21 (the temperature of the corresponding amplifier 21) to the temperature monitoring unit 61.

[0043] The temperature monitoring unit 61 receives detection results from each of the multiple temperature sensors 60. Based on the detection results received by the temperature monitoring unit 61, functions related to the generation of an oscillation signal in the oscillator 20 are controlled. For example, based on the multiple detection results received by the temperature monitoring unit 61, at least one of frequency control, phase control, and amplitude control of the oscillation signal is controlled. Specifically, when all of the multiple detected temperatures are equal to or higher than a first threshold, the signal generating unit 10 is controlled to stop irradiating microwaves. When at least one of the multiple detected temperatures is lower than the first threshold and equal to or higher than a second threshold, at least one of frequency control, phase control, and amplitude control of the irradiated microwaves is controlled. For example, when frequency control is performed, the signal generating unit 10 is controlled to change the frequency of the microwaves from a first frequency to a second frequency. Here, the second frequency is a frequency lower than the first frequency. When phase control is performed, the phase of the irradiated microwaves is synchronized with an external reference signal by injection locking or the like. Furthermore, when amplitude control is performed, the power supply voltage is controlled so that the amplitude of the irradiated microwaves is reduced. When all of the plurality of detected temperatures are lower than the second threshold, no control is performed on the signal generating unit 10.

[0044] The control based on the detection result of the temperature sensor 60 may be performed by the signal output device 1, the feedback control unit 24, or an external device.

[0045] The output terminal 70 is provided between the first phase shifter 40 and the antenna 100. The output terminal 70 is electrically connected to both the first phase shifter 40 and the antenna 100. The output terminal 70 outputs the oscillation signal (microwave) output from the first phase shifter 40 to the antenna 100.

[0046] (3) Operation Next, the operation of the signal output device 1 will be described.

[0047] The oscillator 20 passes feedback signals having different phases through a plurality of amplifiers 21, and generates an oscillation signal by combining the feedback signals that have passed through the plurality of amplifiers 21.

[0048] The frequency detection unit 30 detects the frequency of the oscillation signal output from the oscillator 20. The phase control unit 50 varies the frequency of the oscillation signal using 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. The first phase shifter 40 changes the phase of the oscillation signal under the control of the phase control unit 50.

[0049] The oscillation signal whose phase has been changed by the first phase shifter 40 is radiated as a microwave from the antenna 100 into the hangar 3 .

[0050] Furthermore, the antenna 100 receives reflected waves of the irradiated microwaves. When the reflected waves are received and the reflected signals of the received reflected waves are input to each of the plurality of amplifiers 21, the temperature of each of the plurality of amplifiers 21 rises. Therefore, the plurality of temperature sensors 60 detect the temperature of the corresponding amplifier 21, and the temperature monitoring unit 61 monitors the results.

[0051] Furthermore, even when there is no reflected wave, if the temperature of the signal output device 1 rises due to a decrease in the cooling capacity of the cooling mechanism of the signal output device 1, the multiple temperature sensors 60 detect the temperature of the corresponding amplifiers 21, and the temperature monitoring unit 61 monitors the results.

[0052] The function of generating an oscillation signal in the signal generating unit 10 is controlled based on the temperatures of the amplifiers 21 monitored by the temperature monitoring unit 61, i.e., the detection results (detected temperatures) detected by the temperature sensors 60.

[0053] (4) Effects As described above, the signal output device 1 according to the first embodiment outputs an oscillation signal for generating microwaves to be irradiated onto food and drink. The signal output device 1 includes an oscillator 20 that generates an oscillation signal, a phase shifter (first phase shifter 40), and a phase control unit 50. The oscillator 20 outputs the oscillation signal to an antenna that irradiates the microwaves. The phase shifter is provided at the output destination of the oscillator 20 and changes the load impedance seen from the oscillator 20 toward the antenna 100. In the phase control unit 50, the phase shifter controls the load impedance of the oscillator 20 in accordance with the oscillation frequency of the oscillation signal.

[0054] This configuration allows for the irradiation of microwaves appropriate for the frequency of the oscillation signal, thereby achieving high performance even when irradiating microwaves onto food and drink.

[0055] 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 that performs feedback control on the signal generating unit 10. The oscillator 20 passes oscillation signals having different phases through the plurality of amplifiers 21, and generates an oscillation signal by combining the feedback signals that have passed through the plurality of amplifiers 21.

[0056] 4A shows the load characteristics of the frequency of the oscillation signal when the output destination of the antenna 100 (e.g., inside the hangar 3) is seen from the multiple amplifiers 21 in the signal output device 1. FIG. 4B shows the load characteristics of the output power when the output destination of the antenna 100 (e.g., inside the hangar 3) is seen from the multiple amplifiers 21 in the signal output device 1. That is, FIGS. 4A and 4B show the load characteristics of the frequency and the load characteristics of the output power when the output destination of the antenna 100 is seen from the multiple amplifiers 21 in the signal output device 1 when oscillation signals having different phases from each other are passed through the multiple amplifiers 21. Region L10 shown in FIG. 4A is the range of available oscillation frequencies relative to the impedance of the load characteristics when the output destination of the antenna 100 is seen from the oscillator 20 in the signal output device 1 when oscillation signals having different phases from each other are passed through the multiple amplifiers 21. The region L11 shown in Figure 4B is the range of available output power relative to the impedance of the load characteristics when looking at the output destination of the antenna 100 from the oscillator 20 in the signal output device 1 when feedback signals of different phases are passed through multiple amplifiers 21.

[0057] 5A shows a range of available oscillation frequencies relative to the impedance of the load characteristics when an oscillation signal having the same phase is passed through the multiple amplifiers in a signal output device including multiple amplifiers connected in parallel (hereinafter referred to as a comparative signal output device). Also, the range of available output power relative to the impedance of the load characteristics when an oscillation signal having the same phase is passed through the multiple amplifiers in the comparative signal output device.

[0058] 4A and 5A, region L10 as the load characteristic of the oscillation frequency available for the oscillator 20 in the signal output device 1 is wider than region L20 as the load characteristic of the oscillation frequency available for the oscillator 20 in the signal output device of the comparative example. Similarly, according to Figures 4B and 5B, region L11 as the load characteristic of the output power available for the oscillator 20 in the signal output device 1 is wider than region L21 as the load characteristic of the output power available for the oscillator 20 in the signal output device of the comparative example.

[0059] Therefore, by passing oscillation signals having different phases through multiple amplifiers 21, the range of impedance of the load characteristics of the available oscillation frequency and the range of impedance of the load characteristics of the available output power can be expanded.

[0060] (5) Modifications Modifications are listed below. The modifications described below can be applied in appropriate combination with the first embodiment.

[0061] (5.1) Modification 1 In the first embodiment, the antenna 100 is not a component of the signal output device 1, but the signal output device 1 may include the antenna 100 as a component.

[0062] (5.2) Modification 2 In the first embodiment, the oscillator 20 includes a plurality of amplifiers 21 connected in parallel. However, the present invention is not limited to this configuration.

[0063] The oscillator 20 may be configured to include one amplifier 21. In this case, the signal output device 1 is equipped with one temperature sensor 60. The temperature sensor 60 detects the temperature of the one amplifier 21 included in the oscillator 20. The frequency detection unit 30 detects the frequency of the oscillation signal output by the oscillator 20 including the one amplifier 21. The phase control unit 50 controls the first phase shifter 40 to change the phase of the oscillation signal according to the detected frequency.

[0064] (5.3) Modification 3 The oscillator 20 may be configured such that a part or all of the phase change amount of the second phase shifter 22 is included in the divider 25 that distributes the feedback signal to the plurality of amplifiers 21. Furthermore, a part or all of the phase change amount of the third phase shifter 23 may be included in the combiner 26 that combines the outputs of the plurality of amplifiers 21.

[0065] (5.4) Modification 4 In the first embodiment, the oscillator 20 is configured to pass oscillation signals having different phases from each other through the multiple amplifiers 21. However, the present invention is not limited to this configuration. The oscillator 20 may pass oscillation signals having different phases from each other through at least two of the multiple amplifiers 21.

[0066] (5.5) Modification 5 In the first embodiment, the load impedance seen from the oscillator 20 toward the antenna 100 is changed by the first phase shifter 40, but it is also possible to change not only the phase but also the impedance.

[0067] Second Embodiment A second embodiment differs from the first embodiment in that the oscillator is an amplifier type oscillator.

[0068] The configuration of a signal output device 1A according to the second embodiment will be described below, focusing on the differences from the first embodiment. Note that the same components as those in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0069] The signal output device 1A according to the second embodiment is applied to an electrical appliance 2, similar to the first embodiment. Here, the electrical appliance 2 to which the signal output device 1A is applied is a microwave oven, a refrigerator, or a freezer. That is, the electrical appliance 2 according to the second embodiment includes the signal output device 1A and a storage unit 3.

[0070] 6, 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 an output terminal 70 electrically connected to a plurality of (two in the illustrated example) temperature sensors 60, a temperature monitoring unit 61, and an antenna 100 (see FIG. 2).

[0071] The signal generator 80 includes a signal generating section 10A and a frequency detecting section 30A.

[0072] The signal generating unit 10A is a semiconductor microwave oscillator that controls the frequency and generates (oscillates) an oscillation signal that serves as the basis for microwaves of a predetermined frequency. The signal generating unit 10A performs phase control. The signal generating unit 10A has, for example, a quadrature modulation circuit, and changes the phase of the oscillation signal. Furthermore, the signal generating unit 10A performs gain control, i.e., amplitude control of the oscillation signal. The signal generating unit 10A adjusts the gain of the oscillation signal.

[0073] The frequency detector 30A detects the frequency of the oscillation signal generated by the signal generator 10A.

[0074] The oscillator 20A includes, for example, a power amplifier 200.

[0075] The power amplifier 200 amplifies the oscillation signal and outputs it to the electrically connected antenna 100. The power amplifier 200 includes a device group 201 configured of multiple devices, a final-stage device 202, a distributor 25, and a combiner 26A. The multiple devices included in the device group 201 and the final-stage device 202 are, for example, transistors. Hereinafter, the device 202 will also be referred to as the final-stage device 202. The oscillator 20A (power amplifier 200) according to the second embodiment is an amplifier-type oscillator that includes the multiple devices included in the device group 201 and the final-stage device 202 and amplifies an oscillation signal generated by a so-called signal generator 80 using an amplifier.

[0076] The device group 201 is electrically connected to the signal generating 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 the amplifier 21a and the second phase shifter 22. The final stage device 202 is electrically connected to the 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 (microwave) to the antenna 100 via the output terminal 70.

[0077] 6, the final stage device 202 has a plurality of (two in the illustrated example) amplifiers 211 connected in parallel. When it is necessary to distinguish between the plurality of amplifiers 211, they are referred to as amplifiers 211a and 211b.

[0078] The combiner 26A of the oscillator 20A (power amplifier 200) combines the oscillation signal output by the amplifier 211b and the oscillation signal whose phase has been shifted by the third phase shifter 23. Specifically, the combiner 26A passes oscillation signals of different phases through the multiple amplifiers 211, and combines the oscillation signals that have passed through the multiple amplifiers 211.

[0079] An oscillation signal whose phase is not changed is input to amplifier 211a. Amplifier 211a amplifies the input oscillation signal and outputs the amplified oscillation signal. The oscillation signal output from amplifier 211a is input to third phase shifter 23. The third phase shifter 23 changes the phase of the input oscillation signal. The oscillation signal whose phase has been changed by second phase shifter 22 is input to amplifier 21b. Amplifier 21b amplifies the input oscillation signal (oscillation signal whose phase has been changed) and outputs the amplified oscillation signal. In other words, the phase of the oscillation signal input to and output from amplifier 21a is different from the phase of the oscillation signal input to and output from amplifier 21b. Furthermore, since the amount by which the second phase shifter 22 changes the phase of the oscillation signal is the same as the amount by which the third phase shifter 23 changes the phase of the oscillation signal, the phase of the oscillation signal output from amplifier 211b and the phase of the oscillation signal changed by the third phase shifter 23 are the same.

[0080] The oscillator 20A outputs to the first phase shifter 40 an oscillation signal obtained by combining the oscillation signal amplified by the amplifier 211a and the oscillation signal amplified by the amplifier 211b.

[0081] The phase control unit 50A 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 50A controls the first phase shifter 40 so that the first phase shifter 40 changes the load impedance of the oscillator 20 in accordance with the oscillation frequency of the oscillation signal. For example, the phase control unit 50A controls the first phase shifter 40 so that the first phase shifter 40 changes the phase of the oscillation signal in accordance with the frequency of the oscillation signal detected by the frequency detection unit 30A. The phase control unit 50A varies the frequency of the oscillation signal using the first phase shifter 40 based on the frequency detected by the frequency detection unit 30A. The impedance characteristics of the antenna 100 as seen from the oscillator 20A vary depending on the frequency of the irradiated microwaves. The phase control unit 50 varies the frequency of the oscillation signal using the first phase shifter 40 based on the frequency detected by the frequency detection unit 30A so that the impedance of the antenna 100 falls within an appropriate range. That is, based on the frequency detected by the frequency detection unit 30A, the phase control unit 50A controls the first phase shifter 40 to change the load impedance of the antenna 100 as seen from the oscillator 20A so that the impedance of the antenna 100 falls within an appropriate range.

[0082] The plurality of temperature sensors 60 detect the temperatures of the plurality of amplifiers 211, respectively. The plurality of temperature sensors 60 are associated one-to-one with the plurality of amplifiers 211, and detect the temperatures of the associated amplifiers 211. Each of the plurality of temperature sensors 60 outputs the detection result for the corresponding amplifier 211 (the temperature of the corresponding amplifier 211) to the temperature monitoring unit 61.

[0083] The temperature monitoring unit 61 receives detection results from each of the multiple temperature sensors 60. Based on each detection result received by the temperature monitoring unit 61, functions related to generation of an oscillation signal in the signal generating unit 10A are controlled. For example, based on the multiple detection results received by the temperature monitoring unit 61, at least one of frequency control, phase control, and amplitude control of the oscillation signal is controlled.

[0084] The control of the signal generating unit 10A based on the detection result of the temperature sensor 60 may be performed by the signal output device 1A or an external device.

[0085] Next, the operation of the signal output device 1A will be described.

[0086] The signal generating unit 10A generates an oscillation signal of a predetermined frequency in order to irradiate microwaves of the predetermined frequency. The signal generating unit 10A generates the oscillation signal of the predetermined frequency and performs gain adjustment and the like on the generated oscillation signal. At this time, the frequency detecting unit 30A detects the frequency of the generated oscillation signal.

[0087] The oscillator 20A (power amplifier 200) amplifies an oscillation signal using a device group 201 and a final-stage device 202. At this time, the final-stage device 202 passes oscillation signals of different phases through a plurality of amplifiers 211, and combines the oscillation signals that have passed through the plurality of amplifiers 211.

[0088] Based on the frequency detected by the frequency detection unit 30A, the phase control unit 50A varies the first phase shifter 40 in accordance with the frequency of the oscillation signal so that the impedance of the antenna 100 falls within an appropriate range. The first phase shifter 40 changes the load impedance of the antenna 100 as seen from the oscillator 20A under the control of the phase control unit 50A.

[0089] The oscillation signal whose phase has been changed by the first phase shifter 40 is radiated as a microwave from the antenna 100 into the hangar 3 .

[0090] Furthermore, the antenna 100 receives reflected waves of the irradiated microwaves. When the reflected waves are received and the reflected signals of the received reflected waves are input to each of the plurality of amplifiers 211 of the final stage device 202, the temperature of each of the plurality of amplifiers 211 rises. Therefore, the plurality of temperature sensors 60 detect the temperature of the corresponding amplifier 211, and the temperature monitoring unit 61 monitors the results.

[0091] Furthermore, even when there is no reflected wave, if the temperature of the signal output device 1A rises due to a decrease in the cooling capacity of the cooling mechanism of the signal output device 1A, the multiple temperature sensors 60 detect the temperature of the corresponding amplifiers 211, and the temperature monitoring unit 61 monitors the results.

[0092] The function of generating an oscillation signal in the signal generating unit 10A is controlled based on the temperatures of the amplifiers 211 monitored by the temperature monitoring unit 61, that is, the detection results (detected temperatures) detected by the temperature sensors 60.

[0093] The signal output device 1A according to the second embodiment can also irradiate microwaves appropriate for the frequency of the oscillation signal, similar to the first embodiment. Therefore, high performance can be achieved even when irradiating microwaves onto food and drink.

[0094] Furthermore, in the signal output device 1A, by passing oscillation signals with different phases through the multiple amplifiers 211, the impedance range of the frequency load characteristics and the impedance range of the output power load characteristics can be widened.

[0095] In the second embodiment, the oscillator 20A (power amplifier 200) may be provided between the signal generating unit 10A and the device group 201 and may have a matching circuit for matching impedances between the signal generating unit 10A and the device group 201. Furthermore, the oscillator 20A (power amplifier 200) may be provided between the device group 201 and the final stage device 202 and may have a matching circuit for matching impedances between the device group 201 and the final stage device 202. Furthermore, the oscillator 20A (power amplifier 200) may be provided between the first phase shifter 40 and the output terminal 70 and may have a matching circuit for matching impedances between the first phase shifter 40 and the output terminal 70 and between the first phase shifter 40 and a configuration connected beyond the output terminal 70, such as the antenna 100.

[0096] Furthermore, in the second embodiment, the oscillator 20A is configured to pass oscillation signals having different phases from each other through the two amplifiers 211. However, this configuration is not limiting. The oscillator 20A may pass oscillation signals having different phases from each other through at least two of the three or more amplifiers 211. The oscillator 20A may be configured such that a divider 25 that distributes the oscillation signal to the multiple amplifiers 211 includes some or all of the phase change amount of the second phase shifter 22. Furthermore, a combiner 26A that combines the outputs of the multiple amplifiers 211 may be configured such that a combiner 26A that combines the outputs of the multiple amplifiers 211 includes some or all of the phase change amount of the third phase shifter 23.

[0097] Furthermore, in the second embodiment, the first and second modifications of the first embodiment may be applied.

[0098] (Summary) As described above, the signal output device (1; 1A) of the first aspect outputs an oscillation signal for generating microwaves to be irradiated onto food and beverages. The signal output device (1; 1A) includes an oscillator (20; 20A), a phase shifter (e.g., a first phase shifter 40), and a phase control unit (50; 50A). The oscillator (20; 20A) outputs an oscillation signal to an antenna (100) that irradiates microwaves. The phase shifter is provided at the output destination of the oscillator (20; 20A) and changes the load impedance seen from the oscillator (20; 20A) toward the antenna (100). The phase control unit (50; 50A) controls the phase shifter so that the phase shifter changes the load impedance of the oscillator (20; 20A) in accordance with the oscillation frequency of the oscillation signal.

[0099] According to this aspect, it is possible to irradiate microwaves appropriate for the frequency of the oscillation signal, thereby achieving high performance even when irradiating microwaves onto food and drink.

[0100] In the signal output device (1A) of the second aspect, the oscillator (20A) of the first aspect includes a power amplifier (200). The power amplifier (200) includes a final stage device (202) having a plurality of amplifiers (211) connected in parallel. The power amplifier (200) passes oscillation signals of different phases through the plurality of amplifiers (211) and combines the oscillation signals that have passed through each of the plurality of amplifiers (211).

[0101] According to this embodiment, it is possible to widen the range of impedance of the load characteristics of the available frequency and the range of impedance of the load characteristics of the available output power.

[0102] In the signal output device (1) of the third aspect, in 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 feedback signals to the plurality of amplifiers (21) by feedback control of the plurality of amplifiers (21). The oscillator (20) passes feedback signals of different phases through the plurality of amplifiers (21) and generates an oscillation signal by combining the feedback signals that have passed through each of the plurality of amplifiers (21).

[0103] According to this embodiment, it is possible to widen the range of impedance of the load characteristics of the available frequency and the range of impedance of the load characteristics of the available output power.

[0104] The signal output device (1; 1A) of the fourth aspect is the first aspect, further comprising a temperature sensor (60). The oscillator (20; 20A) includes an amplifier (21; 211). The temperature sensor (60) detects the temperature of the amplifier (21).

[0105] According to this embodiment, by monitoring the temperature of the amplifier (21), it is possible to more accurately control the irradiation of microwaves, i.e., control the output of the oscillation signal.

[0106] The signal output device (1; 1A) of a fifth aspect is the second or third aspect, further comprising a plurality of temperature sensors (60) for detecting the temperatures of the plurality of amplifiers (21; 211), respectively.

[0107] According to this embodiment, by monitoring the temperature of the amplifier (21), it is possible to more accurately control the irradiation of microwaves, i.e., control the output of the oscillation signal.

[0108] A sixth aspect of the signal output device (1, 1A) is any one of the first to fifth aspects, further comprising a frequency detection unit (30; 30A). The frequency detection unit (30; 30A) detects the frequency of the oscillation signal output from the oscillator (20; 20A). The phase control unit (50) controls the phase shifter so that the phase shifter changes the phase of the oscillation signal based on the frequency detected by the frequency detection unit (30; 30A).

[0109] According to this embodiment, it is possible to irradiate an appropriate microwave according to the frequency of the oscillation signal.

[0110] A microwave oven (2a) of a seventh aspect includes the signal output device (1; 1A) of any one of the first to sixth aspects and a storage compartment (3). The storage compartment (3) stores an object to be irradiated with microwaves irradiated from the signal output device (1; 1A) via the antenna (100).

[0111] According to this embodiment, high performance can be achieved even when microwaves are irradiated onto food and drink.

[0112] A refrigerator according to an eighth aspect includes the signal output device (1; 1A) according to any one of the first to sixth aspects and a storage compartment (3). The storage compartment (3) stores an object to be irradiated with microwaves irradiated from the signal output device (1; 1A) via an antenna (100).

[0113] According to this embodiment, high performance can be achieved even when microwaves are irradiated onto food and drink.

[0114] A freezer according to a ninth aspect includes the signal output device (1; 1A) according to any one of the first to sixth aspects and a storage compartment (3). The storage compartment (3) stores an object to be irradiated with microwaves irradiated from the signal output device (1; 1A) via an antenna (100).

[0115] According to this embodiment, high performance can be achieved even when microwaves are irradiated onto food and drink.

[0116] REFERENCE SIGNS LIST 1, 1A Signal output device 2 Electrical equipment 2a Microwave oven 3 Storage 20, 20A Oscillator 21, 21a, 21b Amplifier 24 Feedback control section 25 Distributor 26, 26A Combiner 30, 30A Frequency detection section 40 First phase shifter (phase shifter) 50, 50A Phase control section 60 Temperature sensor 100 Antenna 200 Power amplifier 211, 211a, 211b Amplifier 202 Final stage device (device)

Claims

1. A signal output device that outputs an oscillation signal for generating microwaves to be irradiated onto food and drink, an oscillator that outputs the oscillation signal to an antenna that irradiates the microwave; a phase shifter provided at an output destination of the oscillator and configured to change a load impedance when the antenna is viewed from the oscillator; a phase control unit that controls the phase shifter so that the phase shifter changes the load impedance of the oscillator in accordance with the oscillation frequency of the oscillation signal, Signal output device.

2. the oscillator includes a power amplifier; the power amplifier includes a final stage device having a plurality of amplifiers connected in parallel; the power amplifier passes the oscillation signals having different phases through the plurality of amplifiers, and combines the oscillation signals that have passed through the plurality of amplifiers.

2. The signal output device according to claim 1.

3. The oscillator comprises: a plurality of amplifiers connected in parallel; a feedback control unit that outputs a feedback signal to the plurality of amplifiers by feedback control of the plurality of amplifiers, the oscillator passes the feedback signals having different phases through the plurality of amplifiers, and generates the oscillation signal by combining the feedback signals that have passed through the plurality of amplifiers.

2. The signal output device according to claim 1.

4. Further comprising a temperature sensor; the oscillator includes an amplifier; the temperature sensor detects the temperature of the amplifier; 2. The signal output device according to claim 1.

5. further comprising a plurality of temperature sensors that detect temperatures of the plurality of amplifiers, respectively; 4. The signal output device according to claim 2 or 3.

6. a frequency detection unit that detects the frequency of the oscillation signal output from the oscillator, the phase control unit controls the phase shifter so that the phase shifter changes the phase of the oscillation signal based on the frequency detected by the frequency detection unit. The signal output device according to any one of claims 1 to 4.

7. A signal output device according to any one of claims 1 to 4; a storage facility for storing an object to be irradiated with the microwave irradiated from the signal output device via the antenna, microwave oven.

8. A signal output device according to any one of claims 1 to 4; a storage facility for storing an object to be irradiated with the microwave irradiated from the signal output device via the antenna, refrigerator.

9. A signal output device according to any one of claims 1 to 4; a storage facility for storing an object to be irradiated with the microwave irradiated from the signal output device via the antenna, freezer.