Microwave heating method using microwaves and heating device

Abstract

To heat an object to be heated from the inside using microwaves.SOLUTION: A heating method includes ultrasonically vibrating a rod containing a conductor that functions as an antenna and inserting the rod into an object to be heated, and radiating microwaves from the antenna once the rod is inserted into the object to be heated.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heating method and a heating device using microwaves. [Background technology]

[0002] Generally, a method is known in which a heated object is heated by irradiating the object with microwaves and using dielectric heating. In dielectric heating using microwaves, the microwaves are generally irradiated from outside the heated object. In this case, the conditions for appropriate heating may vary depending on the state of the heated object.

[0003] For example, Patent Document 1 discloses a technique related to a microwave heating device capable of performing appropriate heating control according to the state of the heated object. This microwave heating device has a rotatable waveguide structure antenna configured to radiate microwaves into a power supply chamber provided below the heating chamber in which the heated object is placed. The waveguide structure antenna has a tip open portion that radiates microwaves toward the side wall of the power supply chamber, and a microwave suction opening that forms the microwaves into circularly polarized waves and radiates them toward the heating chamber. This microwave heating device controls heating according to the state of the heated object by lengthening the time that the tip open portion faces an area including the corners of the power supply chamber, or lengthening the time that the tip open portion does not face an area including the corners of the power supply chamber.

[0004] There are various demands regarding heating using microwaves, not limited to those that can be solved by the above examples. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-119254 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to make it possible to heat an object from the inside using microwaves. [Means for solving the problem]

[0007] According to one aspect of the present invention, a heating method includes ultrasonically vibrating a rod including a conductor that functions as an antenna, inserting the rod into an object to be heated, and radiating microwaves from the antenna once the rod is inserted into the object to be heated. Effect of the Invention

[0008] According to the present invention, an object to be heated can be heated from the inside using microwaves. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing an outline of a configuration example of a heating device according to a first embodiment. [Diagram 2] FIG. 2 is a flowchart showing an outline of an operation example of the heating device according to the first embodiment. [Diagram 3] FIG. 3 is a block diagram showing an outline of a configuration example of a heating device according to the second embodiment. [Figure 4] FIG. 4 is a flowchart showing an outline of an operation example of the heating device according to the second embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of an experimental result using an experimental device corresponding to the first embodiment. [Figure 6] FIG. 6 is a diagram showing an example of an experimental result using an experimental device corresponding to the first embodiment. [Figure 7] FIG. 7 is a diagram showing an example of an experimental result using an experimental device corresponding to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [First embodiment] The first embodiment will be described with reference to the drawings. The heating device of the first embodiment is configured to heat an object to be heated by dielectric heating caused by microwave radiation. In particular, in this heating device, an antenna that radiates microwaves is configured to be inserted into the object to be heated. That is, this heating device is configured to heat the object by radiating microwaves from inside the object to be heated. In addition, the heating device of the first embodiment is configured such that when a rod including the antenna is inserted into the object to be heated, the rod is ultrasonically vibrated. By ultrasonically vibrating the rod, the rod including the antenna can be easily inserted into the object to be heated even if the object to be heated is hard.

[0011] <Configuration of Heating Device> The configuration of the heating device 1 according to the first embodiment will be described below. Fig. 1 is a block diagram showing an outline of a configuration example of the heating device 1 according to the first embodiment.

[0012] The heating device 1 includes a rod 12 including a conductor such as a metal that functions as an antenna for radiating microwaves. The rod 12 may be, for example, a metal itself that functions as an antenna, or a metal that functions as an antenna covered with resin or the like. This antenna is, for example, a monopole antenna. Therefore, the length of this metal has, for example, a 1 / 4 wavelength or 3 / 4 wavelength of the radiated microwave. For example, when the frequency of the output microwave is 2.45 GHz, one wavelength is 12.24 cm in a vacuum, so theoretically, the length of the antenna in this case can be an integer multiple of this 1 / 4 wavelength, 3.06 cm. The length of the antenna may be adjusted depending on the dielectric constant of the object to be heated, etc. Also, impedance matching may be performed using a tuner or the like depending on the length of the antenna and the object to be heated, etc.

[0013] The heating device 1 includes an ultrasonic transducer 22 and an ultrasonic oscillator 24 for ultrasonically vibrating the rod 12. The ultrasonic transducer 22, which is a vibration source of ultrasonic vibration, is connected to the rod 12 and generates ultrasonic vibration based on an input signal from the ultrasonic oscillator 24. The vibration generated by the ultrasonic transducer 22 causes the rod 12 to ultrasonically vibrate.

[0014] The heating device 1 includes a cable 32 and a microwave oscillator 34 for making the rod 12 function as an antenna that radiates microwaves. The metal of the rod 12 that functions as an antenna is connected to the microwave oscillator 34 via a cable 32 such as a coaxial cable. The metal of the rod 12 that functions as an antenna radiates microwaves when microwave power is supplied from the microwave oscillator 34.

[0015] The heating device 1 includes a control device 42 that controls the operation of the ultrasonic oscillator 24 and the microwave oscillator 34. The control device 42 is, for example, a computer having an integrated circuit such as a central processing unit (CPU) or a field programmable gate array (FPGA), and operates, for example, according to a predetermined program. The control device 42 controls the operation of the ultrasonic oscillator 24 so as to oscillate the ultrasonic transducer 22 and ultrasonically vibrate the rod 12 as necessary. The control device 42 also controls the operation of the microwave oscillator 34 so as to feed power to the antenna of the rod 12 and radiate microwaves from the antenna. For example, the control device 42 is configured to control the operation of the ultrasonic oscillator 24 and the microwave oscillator 34 so as to oscillate the ultrasonic transducer 22 and ultrasonically vibrate the rod 12 until the rod 12 is inserted into the object to be heated, and to stop the oscillation of the ultrasonic transducer 22 when the rod 12 is inserted into the object to be heated, and to feed power from the microwave oscillator 34 to the antenna and radiate microwaves from the antenna.

[0016] For example, the portion including the rod 12 and the ultrasonic vibrator 22 may be configured to be held by a user of the heating device 1, and the rod 12 may be inserted into the object to be heated manually by the user. In this case, the operations of ultrasonic vibration and microwave radiation may also be manually operated by the user. Also, for example, the portion including the rod 12 and the ultrasonic vibrator 22 may be configured to be held by an actuator, and the rod 12 may be inserted into the object to be heated using the actuator. In this case, the operations of ultrasonic vibration and microwave radiation may also be automatically controlled by the control device 42.

[0017] <Operation of the heating device> The operation of the heating device 1 according to the first embodiment will be described. FIG. 2 is a flowchart showing an outline of an example of the operation of the heating device 1 according to the first embodiment. Here, an example will be described in which the operation of the heating device 1 is automatically controlled by the control device 42. Some of the operations described here may be performed manually. For example, the on / off operation of ultrasonic vibration or microwave radiation may be performed by the user. In addition, some operations may be omitted, or other operations may be added.

[0018] In step S101, the control device 42 causes the ultrasonic oscillator 24 to start outputting ultrasonic waves. That is, the ultrasonic oscillator 24 outputs an ultrasonic oscillation signal to the ultrasonic transducer 22, causing the ultrasonic transducer 22 to ultrasonically oscillate and the rod 12 to vibrate at an ultrasonic frequency. While the rod 12 is ultrasonically vibrating, the rod 12 is inserted into the object to be heated. As the rod 12 is ultrasonically vibrating, the rod 12 can be smoothly inserted into the object to be heated.

[0019] In step S102, the control device 42 judges whether or not the rod 12 has been inserted into the object to be heated up to a predetermined position. Whether or not the rod 12 has been inserted into the object to be heated up to a predetermined position may be judged based on the output of a sensor that detects the position of the rod 12, may be judged based on an input by a user indicating that the rod 12 has been inserted, or may be judged based on other information. The ultrasonic vibration of the rod 12 continues until the rod 12 has been inserted into the object to be heated up to the predetermined position. When it is judged that the rod 12 has been inserted into the object to be heated up to the predetermined position, the process proceeds to step S103.

[0020] In step S103, the control device 42 stops the ultrasonic output from the ultrasonic oscillator 24. As a result, the ultrasonic vibration of the rod 12 stops.

[0021] In step S104, the control device 42 causes the microwave oscillator 34 to start outputting microwave power. That is, the microwave oscillator 34 supplies microwave power to the metal of the rod 12 functioning as an antenna. This power supply causes the metal to function as an antenna and radiate microwaves. When microwaves are radiated from the antenna inserted inside the object to be heated, the object to be heated is dielectrically heated by the microwaves radiated from inside the object.

[0022] In step S105, the control device 42 judges whether or not the heating of the object to be heated is completed. Whether or not the heating of the object to be heated is completed may be judged, for example, based on whether the temperature of the object to be heated is measured and whether the temperature of the object to be heated reaches a predetermined temperature. Also, for example, it may be judged based on whether the radiation time of microwaves from the antenna continues for a predetermined time. It may also be judged based on an input by the user. Alternatively, it may be judged by other methods. Radiation of microwaves from the rod 12 continues until heating of the object to be heated is completed. When it is judged that heating of the object to be heated is completed, the process proceeds to step S106.

[0023] In step S106, the control device 42 stops the output of microwave power from the microwave oscillator 34. As a result, the radiation of microwaves from the rod 12 stops.

[0024] In step S107, the control device 42 causes the ultrasonic oscillator 24 to start outputting ultrasonic waves again. That is, the ultrasonic oscillator 24 outputs an ultrasonic oscillation signal to the ultrasonic transducer 22, causing the ultrasonic transducer 22 to ultrasonically oscillate and the rod 12 to vibrate at an ultrasonic frequency. While the rod 12 is ultrasonically vibrating, the rod 12 is removed from the object to be heated. As the rod 12 is ultrasonically vibrating, the rod 12 can be smoothly removed from the object to be heated.

[0025] In step S108, the control device 42 judges whether the rod 12 has been completely removed from the object to be heated. The judgment method may be the same as that of the insertion in step S102. The ultrasonic vibration of the rod 12 continues until the rod 12 is completely removed from the object to be heated. When it is judged that the rod 12 has been completely removed from the object to be heated, the process proceeds to step S109.

[0026] In step S109, the control device 42 stops the ultrasonic output from the ultrasonic oscillator 24. As a result, the ultrasonic vibration of the rod 12 stops. With this, the series of operations of the heating device 1 ends.

[0027] <Use of heating device, etc.> The heating device 1 of the first embodiment is a heating device suitable for heating an object whose inside needs to be heated or whose inside is difficult to heat.

[0028] A common method of dielectric heating using microwaves is to irradiate microwaves from the outside of an object placed in a metal box. In this case, the microwaves travel from the surface of the object to the center. The energy of the microwaves, which are electromagnetic waves, gradually changes into heat as they travel inside the object, and can only penetrate to a certain depth from the surface. Therefore, in objects with high density and high microwave absorption, all of the microwave energy changes into heat near the surface, and the microwaves do not reach the center of the object, and the inside of the object may not be heated.

[0029] For example, microwaves are generally used to heat and thaw frozen foods. However, it is known that it is difficult to uniformly thaw and heat foods by irradiating microwaves from the outside, for example, frozen foods with high density and high microwave absorption, such as frozen bean paste bread, frozen hamburger steak, and frozen gratin. If such foods are irradiated with microwaves until the inside is sufficiently heated, the outside, which is easily heated, will be overheated, and the quality of the food will decrease. This bad situation is even more pronounced in the case of a heated object whose inside is difficult to heat, such as frozen bean paste bread with a high density bean paste inside.

[0030] In contrast, according to the heating device 1 of the first embodiment, microwaves are irradiated from the inside of the object to be heated, so that the object is heated by heat generated from the inside. As a result, even frozen foods that are difficult to heat evenly when irradiated with microwaves from the outside can be thawed and heated uniformly. The heating time can also be shortened. This method is particularly suitable for objects that are difficult to heat inside, such as frozen bean-jam bread.

[0031] Furthermore, in general, when the object to be heated is hard, such as a frozen food, it is assumed that it is difficult to insert an antenna that radiates microwaves into the object to be heated. In contrast, in the heating device 1 of the first embodiment, the rod 12 that functions as an antenna can be ultrasonically vibrated when it is inserted into the object to be heated. By ultrasonically vibrating the rod 12, the rod 12 can be smoothly inserted into the object to be heated, such as a hard frozen food.

[0032] Freezing and storing food is also required to reduce food waste, and therefore the heating device 1 of the first embodiment can also contribute to reducing food waste due to its excellent thawing and heating performance.

[0033] As an example of the usage of the heating device 1 of the first embodiment, the case where the heating device 1 is used for thawing and heating frozen foods has been described above. The use of the heating device 1 is not limited to this. The heating device 1 can be used, for example, for heating or drying various foods, materials, substances, etc. The heating device 1 may be used, for example, for heating to solidify adhesive when manufacturing laminated lumber in which wooden boards and the like are bonded together with adhesive. The heating device 1 may also be used, for example, as equipment for surgical procedures. The heating device 1 may be used, for example, for cauterizing living tissue.

[0034] In the operation of the heating device 1 according to the embodiment described above, the rod 12 is ultrasonically vibrated in both cases of insertion and removal of the rod 12, but the ultrasonic vibration of the rod 12 may be performed only when necessary. For example, in heating frozen food, the rod 12 is ultrasonically vibrated when inserting the rod 12 into a hard food in a frozen state, but the food may be soft after thawing and heating. In such a case, it is not necessary to ultrasonically vibrate the rod 12 when removing the rod 12. Also, for example, in heating for solidifying a material, it is not necessary to ultrasonically vibrate the rod 12 when inserting the rod 12 into a soft material before solidification, and the rod 12 may be ultrasonically vibrated when removing the rod 12 from the material after it has been heated and solidified.

[0035] Also, although an example has been shown in which the ultrasonic vibration of the rod 12 and the radiation of microwaves are not performed simultaneously, this is not limiting. The ultrasonic vibration and the radiation of microwaves may be performed simultaneously. For example, while the rod 12 is being ultrasonically vibrated and inserted into the object to be heated, microwaves may be emitted to heat the object to be heated at the same time. Similarly, while the rod 12 is being ultrasonically vibrated and removed from the object to be heated, microwaves may be emitted to heat the object to be heated at the same time.

[0036] [Second embodiment] A second embodiment will be described below, focusing on the differences from the first embodiment, and the same parts are given the same reference numerals and the description thereof will be omitted.

[0037] <Configuration of Heating Device> FIG. 3 is a block diagram showing an outline of a configuration example of the heating device 2 according to the second embodiment. In the heating device 1 according to the first embodiment, a microwave oscillator 34 is connected to the rod 12 functioning as an antenna connected to the ultrasonic vibrator 22 via a cable 32. In contrast, in the heating device 2 according to the second embodiment, the rod 13 functioning as an antenna inserted in the object to be heated is configured to be separated from the ultrasonic vibrator 22. In addition, microwaves are irradiated from the outside to the separated rod 13 functioning as an antenna. When microwaves are irradiated from the outside, the rod 13 functioning as an antenna receives the irradiated microwaves and re-radiates the microwaves. The heating device 2 according to the second embodiment heats the object to be heated by the re-radiated microwaves.

[0038] The basic configuration of the rod 13 functioning as an antenna in the second embodiment is similar to that of the rod 12 functioning as an antenna in the heating device 2 in the first embodiment. The rod 13 is configured to be detachably connected to the ultrasonic transducer 22 via the attachment / detachment device 23. The attachment / detachment device 23 is configured to transmit the vibration generated by the ultrasonic transducer 22 to the rod 13. The attachment / detachment device 23 may include, for example, a screw or the like that connects the rod 13 and the ultrasonic transducer 22. The ultrasonic transducer 22 generates ultrasonic vibrations based on an input signal from the ultrasonic oscillator 24. When the rod 13 and the ultrasonic transducer 22 are connected via the attachment / detachment device 23, the rod 13 is ultrasonically vibrated by the vibration generated by the ultrasonic transducer 22. The rod 13 may be manually attached to and detached from the ultrasonic transducer 22 and the attachment / detachment device 23 using the attachment / detachment device 23, or may be attached and detached under the control of, for example, the control device 42.

[0039] The heating device 2 of the second embodiment includes a microwave irradiating device 35. The microwave irradiating device 35 includes a microwave oscillator 36 including, for example, a magnetron or the like, a housing 38 that blocks microwaves, and a waveguide 37 that guides the microwaves radiated from the microwave oscillator 36 into the housing 38.

[0040] In the heating device 2 of the second embodiment, when the rod 13 is inserted into the object to be heated and then separated from the ultrasonic transducer 22 by the attachment / detachment device 23, the rod 13 alone is inserted into the object to be heated. In the second embodiment, the object to be heated with the rod 13 inserted therein is placed in a housing 38, and microwaves are irradiated from outside the object to be heated in the housing 38 using a microwave oscillator 36.

[0041] The rod 13 irradiated with microwaves from the outside receives the microwaves and re-radiates them. That is, at this time, the rod 13 radiates microwaves from inside the object to be heated into which it is inserted. Therefore, the object to be heated is heated by the microwaves irradiated from the outside of the object to be heated and the microwaves radiated from inside the object to be heated.

[0042] The control device 42 controls the operations of the ultrasonic oscillator 24 and the microwave oscillator 36. The control device 42 may be configured to have two separate control devices, one for controlling the ultrasonic oscillator 24 and one for controlling the microwave oscillator 36.

[0043] <Operation of the heating device> The operation of the heating device 2 according to the second embodiment will be described. FIG. 4 is a flowchart showing an outline of an example of the operation of the heating device 2 according to the second embodiment. Here, the case where the operation of the heating device 1 is automatically controlled by the control device 42 will be described as an example. Some of the operations described here may be performed manually. In addition, some operations may be omitted, or other operations may be added.

[0044] In step S201, the control device 42 causes the ultrasonic oscillator 24 to start outputting ultrasonic waves. That is, the ultrasonic oscillator 24 outputs an ultrasonic oscillation signal to the ultrasonic transducer 22, causing the ultrasonic transducer 22 to ultrasonically oscillate and the rod 13 to vibrate at an ultrasonic frequency. While the rod 13 is ultrasonically vibrating, the rod 13 is inserted into the object to be heated. As the rod 13 is ultrasonically vibrating, the rod 13 can be smoothly inserted into the object to be heated.

[0045] In step S202, the control device 42 judges whether the rod 13 has been inserted into the object to be heated to a predetermined position. The ultrasonic vibration of the rod 13 continues until the rod 13 has been inserted into the object to be heated to the predetermined position. When it is judged that the rod 13 has been inserted into the object to be heated to the predetermined position, the process proceeds to step S203. In step S203, the control device 42 causes the ultrasonic oscillator 24 to stop outputting ultrasonic waves. As a result, the ultrasonic vibration of the rod 13 stops.

[0046] In step S204, the control device 42 causes the attachment / detachment device 23 to separate the rod 13 from the ultrasonic transducer 22. Any separation mechanism may be used for the attachment / detachment device 23. The rod 13 may be separated manually. The separated rod 13 is inserted alone into the object to be heated.

[0047] In step S205, the control device 42 judges whether or not the object to be heated into which the rod 13 is inserted has been placed in the housing 38 of the microwave radiating device 35. The control device 42 waits until the object to be heated is placed in the housing 38. When it is judged that the object to be heated has been placed in the housing 38, the process proceeds to step S206.

[0048] In step S206, the control device 42 causes the microwave oscillator 36 to start emitting microwaves. The microwaves emitted from the microwave oscillator 36 are radiated into the housing 38 via the waveguide 37. A part of the microwaves irradiated to the object to be heated dielectrically heats the object to be heated. Another part of the microwaves is received by the antenna of the rod 13 inserted into the object to be heated. Based on the received microwaves, the antenna of the rod 13 re-radiates microwaves. The re-radiated microwaves dielectrically heat the object to be heated from its interior.

[0049] In step S207, the control device 42 determines whether or not the heating of the object to be heated is completed. The microwave radiation continues until the heating is completed. When it is determined that the heating of the object to be heated is completed, the process proceeds to step S208. In step S208, the control device 42 causes the microwave oscillator 36 to stop emitting the microwave.

[0050] In step S209, the control device 42 causes the attachment / detachment device 23 to attach the rod 13 in the object to be heated to the ultrasonic transducer 22. The attachment mechanism of the attachment / detachment device 23 may be of any type. Also, the attachment of the rod 13 to the ultrasonic transducer 22 may be performed manually.

[0051] In step S210, the control device 42 causes the ultrasonic oscillator 24 to start outputting ultrasonic waves again. That is, the ultrasonic oscillator 24 outputs an ultrasonic oscillation signal to the ultrasonic transducer 22, causing the ultrasonic transducer 22 to ultrasonically oscillate and the rod 13 to vibrate at an ultrasonic frequency. While the rod 13 is ultrasonically vibrating, the rod 13 is removed from the object to be heated. As the rod 13 is ultrasonically vibrating, the rod 13 can be smoothly removed from the object to be heated.

[0052] In step S211, the control device 42 judges whether the rod 13 has been completely removed from the object to be heated. The ultrasonic vibration of the rod 13 continues until the rod 13 has been completely removed from the object to be heated. When it is judged that the rod 13 has been completely removed from the object to be heated, the process proceeds to step S212.

[0053] In step S212, the control device 42 stops the ultrasonic output from the ultrasonic oscillator 24. As a result, the ultrasonic vibration of the rod 13 stops. With this, the series of operations of the heating device 2 ends.

[0054] <Use of heating device, etc.> The heating device 2 of the second embodiment can heat the object from both the outside and the inside by microwaves irradiated from the inside of the object as well as microwaves irradiated from the outside of the object. Therefore, like the heating device 1 of the first embodiment, the heating device 2 of the second embodiment is a heating device suitable for heating an object that needs to be heated inside or an object that is difficult to heat inside.

[0055] In the configuration of the heating device 2 of the second embodiment, the configuration of the rod 13 functioning as an antenna can be made relatively simpler than that of the heating device 2 of the first embodiment. This makes it possible to reduce the cost of the device and to extend the life of the device.

[0056] In the above-mentioned second embodiment, an example was described in which only the rod 13 removed by the attachment / detachment device 23 is installed in the housing 38 of the microwave irradiation device 35 together with the object to be heated, and microwaves are irradiated from the outside, but this is not limited to the above. The rod 13 may not be removed from the ultrasonic vibrator 22, and the object to be heated with the rod 13 inserted therein and the ultrasonic vibrator 22 may be installed together in the housing 38 of the microwave irradiation device 35, and microwaves may be irradiated from the outside. In this case, among the parts that are inserted in the housing 38 of the microwave irradiation device 35, such as the ultrasonic vibrator 22, the parts other than the rod 13 including the antenna are configured to be shielded from microwaves. The shielding of microwaves can be achieved, for example, by covering the part with metal or the like so as to function as a Faraday cage. The range that can be inserted in the housing 38 of the microwave irradiation device 35 can be determined appropriately. For example, the ultrasonic vibrator 22 and the ultrasonic oscillator 24 may be placed in the housing 38 of the microwave irradiation device 35.

[0057] [Experimental Example] As in the examples of using the heating device of each of the above-mentioned embodiments, an experiment was conducted in which an antenna was placed inside food and microwaves were radiated from inside the food to heat the food.

[0058] <Experiment corresponding to the first embodiment> (Experimental Method) An experimental device corresponding to the heating device 1 of the first embodiment described above was configured as follows. A monopole antenna having a metal rod with a length corresponding to 3 / 4 wavelength was used. This monopole antenna and a semiconductor microwave oscillator were connected using a coaxial cable. A household microwave oven with a hole in the top plate was used as a housing for blocking microwaves. The coaxial cable was passed through the hole in the top plate, the monopole antenna was placed inside the housing, and the semiconductor microwave oscillator was placed outside the housing.

[0059] Using the above-mentioned experimental device, an experiment was conducted to heat an object to be heated. A frozen bean paste bread (Ogura bread, manufactured by Yamazaki Baking Co., Ltd.) was used as the object to be heated. This bean paste bread has a structure in which the bread encases the Ogura bean paste placed in the center. For the experiment, an bean paste bread that had been frozen in a freezer for three days and was sufficiently frozen to the inside was used.

[0060] A monopole antenna was inserted through the center of the frozen bean-jam bread to be heated and placed inside the case. Experiments were conducted under two output conditions. In the first condition, the output of the semiconductor microwave oscillator was set to 30 W and the output time was set to 3 minutes. In the second condition, the output of the semiconductor microwave oscillator was set to 170 W and the output time was set to 1 minute.

[0061] A waterproof core thermometer (MF500, manufactured by Chino Corporation) was used to measure the temperature of the bean-jam bread, which was the object to be heated. Temperatures were measured at three locations: the center of the bean-jam filling, the outer part of the bean-jam filling, and the outer surface of the bread. Each experiment was performed three times.

[0062] (Experimental Results) Figure 5 shows the results of an experiment in which the semiconductor microwave oscillator was set to 30 W output for three minutes. Figure 5 shows the average value of three experiments. It was confirmed that there was no difference of more than 8°C between the temperatures obtained in each experiment. The initial temperatures before heating of the center of the red bean paste, the outer part of the red bean paste, and the surface of the bread were -8°C, -10°C, and -12°C, respectively, and the temperatures after heating for three minutes were 1.3°C, 29°C, and 4°C. In addition, the temperature of the surface part of the bread adjacent to the monopole antenna after heating for three minutes was 32°C, which was higher than the other parts.

[0063] The low power level meant that the entire bread was not heated sufficiently. It was confirmed that the red bean paste inside the bean paste bread was heated well. It was revealed that heating was more advanced in the outer part of the red bean paste compared to the central part. This tendency was thought to be based on the antenna characteristics. It was thought that the electrical characteristics of microwaves caused the surface part of the bread adjacent to the monopole antenna to become hot.

[0064] Figure 6 shows the results of an experiment in which the output of the semiconductor microwave oscillator was set to 170 W and the output time was set to 1 minute. Figure 6 shows the average value of three experiments. It was confirmed that there was no difference of more than 8°C between the temperatures obtained in each experiment. The initial temperatures before heating of the center part of the red bean paste, the outer part of the red bean paste, and the surface part of the bread were -8°C, -10°C, and -8°C, respectively, and the temperatures after heating for 1 minute were 52°C, 82°C, and 14°C. In addition, the temperature of the surface part of the bread adjacent to the monopole antenna after heating for 1 minute was 101°C, which was higher than the other parts, and it was confirmed that part of the bread was burnt. Since a relatively large amount of power was input, the red bean paste was sufficiently heated. It was confirmed that the red bean paste part inside the red bean paste bread was particularly well heated.

[0065] <Experiment corresponding to the second embodiment> (Experimental Method) An experimental device corresponding to the heating device 2 of the second embodiment described above was configured as follows. A monopole antenna, which is a metal rod with a length corresponding to 3 / 4 wavelength, was prepared. A household microwave oven (manufactured by IRIS OHYAMA Co., Ltd.) was used as the microwave irradiation device.

[0066] Frozen bean-jam bread (red bean paste bread) was used as the object to be heated. A monopole antenna was inserted through the center of the frozen bean-jam bread to be heated, and the bread was placed in a household microwave oven. The output was 600W, and the output time was 30 seconds. As a comparative experiment, a frozen bean-jam bread without a monopole antenna was also heated in a household microwave oven at 600W output for 30 seconds. A waterproof center thermometer (MF500) was used to measure the temperature of the bean-jam bread.

[0067] (Experimental Results) The experimental results are shown in Figure 7. The initial temperatures before heating of the center of the red bean paste filling, the outer part of the red bean paste filling, and the surface of the bread of the bean paste bread were -10°C, -11°C, and -14°C, respectively. After heating for 30 seconds at an output of 600 W, the temperatures of the center of the red bean paste filling, the outer part of the red bean paste filling, and the surface of the bread of the bean paste bread with a monopole antenna inserted were 30°C, 37°C, and 28°C, respectively. After heating for 30 seconds at an output of 600 W, the temperatures of the center of the red bean paste filling, the outer part of the red bean paste filling, and the surface of the bread of the bean paste bread without a monopole antenna inserted were 9°C, 14°C, and 36°C, respectively.

[0068] In the bean paste bread without a monopole antenna, the temperature of the outer surface of the bread rose, but the temperature of the inner red bean paste did not rise much. In contrast, in the bean paste bread with a monopole antenna, the temperature of both the outer surface and the inner red bean paste rose, and the temperature difference between positions was small. This is thought to be because the monopole antenna received and re-radiated microwaves, so the bean paste bread was heated simultaneously by the microwaves radiated from the outside and the microwaves radiated from the inside, and it was thought to be a result of the monopole antenna functioning as expected.

[0069] As described above, it has become clear that, whether in the configuration of the first embodiment or the configuration of the second embodiment, by inserting a metal rod functioning as a monopole antenna inside the object to be heated, microwaves can be radiated from inside the object to be heated, and the object to be heated from the inside.

[0070] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0071] 1, 2: Heating device 12, 13: Bar 22: ultrasonic transducer, 23: attachment / detachment device, 24: ultrasonic oscillator 32: Cable, 34: Microwave oscillator 35: microwave irradiation device, 36: microwave oscillator, 37: waveguide, 38: housing 42: Control device

Claims

1. A rod containing a conductor that functions as an antenna is vibrated ultrasonically and inserted into the heated object, which is a frozen object. When the rod is inserted into the frozen object, microwaves are emitted from the antenna. A method for heating frozen foods, including those containing frozen foods.

2. The heating method according to claim 1, further comprising vibrating the rod ultrasonically after emitting the microwaves and then removing the rod from the object to be heated.

3. A rod containing a conductor that functions as an antenna is inserted into the inside of a frozen object to be heated, and microwaves are emitted from the antenna. After emitting the microwaves, the rod is vibrated ultrasonically to remove the rod from the object to be heated. A method for heating frozen foods, including those containing frozen foods.

4. An ultrasonic transducer, which is the source of the ultrasonic vibration, is connected to the rod, and a microwave oscillator is connected to the antenna. Emitting microwaves from the antenna includes supplying power to the antenna from the microwave oscillator. The heating method according to any one of claims 1 to 3.

5. The rod is configured to be detachably attached to the ultrasonic transducer, which is the source of the ultrasonic vibration. Emitting microwaves from the antenna includes irradiating the object to be heated, into which the rod is inserted, The heating method according to any one of claims 1 to 3.

6. An ultrasonic transducer, which is the source of the ultrasonic vibration, is connected to the rod. The ultrasonic transducer is configured such that the irradiated microwaves are shielded. Emitting microwaves from the antenna includes irradiating the object to be heated, into which the rod is inserted, The heating method according to any one of claims 1 to 3.

7. The heating method according to any one of claims 1 to 3, wherein the antenna is a monopole antenna.

8. A rod containing a conductor that functions as an antenna and configured to be inserted into a frozen object, An ultrasonic transducer connected to the aforementioned rod, An ultrasonic oscillator connected to the aforementioned ultrasonic transducer, A microwave oscillator connected to the aforementioned antenna, A control device configured to control the operation of the ultrasonic oscillator so as necessary to cause the ultrasonic transducer to oscillate and the rod to vibrate ultrasonically, and to control the operation of the microwave oscillator so that power is supplied from the microwave oscillator to the antenna and microwaves are emitted from the antenna. A heating device for frozen foods equipped with the following features.

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