Microwave irradiation apparatus and microwave maturation apparatus

Abstract

To provide a microwave irradiation device and a microwave ripening device that can reduce communication interference to a wireless communication apparatus.SOLUTION: A microwave irradiation device includes a microwave oscillation unit 30 equipped with a semiconductor oscillator that radiates microwaves, and a control unit 70 that controls the operation of the microwave oscillation unit 30. The control unit 70 has a sweep irradiation function to radiate microwaves while changing the oscillation frequency of the microwave oscillation unit 30 over time from a starting frequency to a higher or lower frequency within a range from a set upper limit frequency value to a lower limit frequency value. The sweep irradiation function includes a function to set the sweep period of the oscillation frequency to a period within a range of 10 to 300 milliseconds, and to set a different starting frequency from the previous one when the oscillation frequency is changed over time and exceeds the range of the upper or lower limit frequency value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a microwave irradiation device and a microwave aging device that irradiate an object with microwaves.

Background Art

[0002] A microwave aging device that irradiates microwaves to age food is known (for example, Patent Document 1). In such a microwave aging device, microwaves of a predetermined frequency are irradiated to vibrate the moisture contained in the food to heat the food. However, if the frequency of the irradiated microwaves overlaps with the frequency used by wireless communication devices, there is a problem that it interferes with the communication of the wireless communication devices. In particular, since the microwave aging device irradiates microwaves for a longer time than heating and cooking appliances such as microwave ovens, interference with wireless communication devices becomes a major problem. In this regard, in Patent Documents 1 to 5, in addition to fixed irradiation in which microwaves are irradiated at a fixed specific frequency when aging food by irradiating microwaves, in order to equalize the distribution of the electromagnetic field in the aging chamber and promote uniform heating (uniform aging) of the food, a technique of performing sweep irradiation in which microwaves are irradiated while changing the frequency of the microwaves every few Hz to several GHz has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

[0004] However, in Patent Document 1, even when performing sweep irradiation to change the microwave frequency, if the frequency is repeatedly changed to only a predetermined specific frequency, there is a problem that collisions of communication signals occur frequently with wireless communication devices that communicate in the frequency band (communication channel) that includes that specific frequency, causing interference.

[0005] The object of this invention is to provide a microwave irradiation device and a microwave maturation device that can reduce communication interference to wireless communication equipment. [Means for solving the problem]

[0006] A microwave irradiation device according to a first aspect of the present invention comprises a microwave oscillation unit equipped with a semiconductor oscillator for irradiating microwaves, and a control unit for controlling the operation of the microwave oscillation unit, wherein the control unit has a sweep irradiation function that irradiates microwaves while changing the oscillation frequency of the microwave oscillation unit over time from a starting frequency to a higher frequency or a lower frequency within a range from a set upper frequency limit to a lower frequency limit, and the sweep irradiation function has a sweep period of the oscillation frequency within a range of 10 to 300 milliseconds, and includes a function to set a different starting frequency from the previous one when the oscillation frequency would exceed the range of the upper frequency limit or the lower frequency limit due to the change over time. In the microwave irradiation device described above, the sweep irradiation function can be configured to change the oscillation frequency over time, with the change in the oscillation frequency per unit time being 20 MHz / second or more. In the microwave irradiation device described above, the sweep irradiation function can be configured such that, when the oscillation frequency is changed over time in the direction of increasing frequency and exceeds the upper limit frequency value, the starting frequency is set to the lower limit frequency value plus the frequency exceeding the upper limit frequency value, or when the oscillation frequency is changed over time in the direction of decreasing frequency and exceeds the lower limit frequency value, the starting frequency is set to the upper limit frequency value minus the frequency exceeding the lower limit frequency value. In the microwave irradiation device described above, the sweep irradiation function can be configured such that, when the oscillation frequency is changed over time in the direction of increasing frequency and exceeds the range of the upper limit frequency value, the starting frequency is set to the upper limit frequency value minus the frequency exceeding the upper limit frequency value, and a first sweep is performed in which the oscillation frequency is changed over time from the starting frequency in the direction of decreasing frequency. After the first sweep, when the oscillation frequency is changed over time in the direction of decreasing frequency and exceeds the range of the lower limit frequency value, the starting frequency is set to the lower limit frequency value plus the frequency exceeding the lower limit frequency value, and a second sweep is performed in which the oscillation frequency is changed over time from the starting frequency in the direction of increasing frequency. In the microwave irradiation device described above, the configuration can be such that the value obtained by subtracting the lower frequency limit from the upper frequency limit is a prime number. In the microwave irradiation device described above, the upper limit frequency value and the lower limit frequency value can be configured to be set within the range of 2400 to 2500 MHz. In the microwave irradiation device described above, the lower limit frequency value can be set to 2420 MHz or higher. In the microwave irradiation device described above, the sweep irradiation function can be configured to continuously increase the oscillation frequency in intervals of 3 to 20 MHz. In the microwave irradiation apparatus described above, the sweep irradiation function can be configured to include the following steps (A), (B), or (C): (A) A first step of repeatedly updating the oscillation frequency to a higher frequency by a predetermined amount from the starting frequency; a second step of updating the oscillation frequency to a starting frequency different from the previous starting frequency if the oscillation frequency exceeds the upper limit frequency value as a result of executing the first step, and repeatedly updating the oscillation frequency to a higher frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous oscillation frequency; a third step of updating the oscillation frequency to a starting frequency different from the previous and the one before that starting frequencies if the oscillation frequency exceeds the upper limit frequency value as a result of executing the second step, and repeatedly updating the oscillation frequency to a higher frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous and the one before that starting frequencies; a fourth step of repeating the first to third steps; (B) A first step of repeatedly updating the oscillation frequency to a lower frequency by a predetermined amount from the starting frequency; A second step in which, if the oscillation frequency exceeds the lower limit frequency value, the oscillation frequency is updated to a starting frequency different from the previous starting frequency, and the oscillation frequency is repeatedly updated to a lower frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous oscillation frequency; A third step in which, if the oscillation frequency exceeds the lower limit frequency value as a result of performing the second step, the oscillation frequency is updated to a starting frequency different from the previous and the one before that starting frequencies, and the oscillation frequency is repeatedly updated to a lower frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous and the one before that oscillation frequencies; A fourth step (C) repeating the first to third steps; A first step in which the oscillation frequency is repeatedly updated to a higher frequency by a predetermined amount from the starting frequency; If the oscillation frequency exceeds the upper limit frequency value as a result of performing the first step, the oscillation frequency is updated to a starting frequency different from the previous starting frequency,A second step of repeatedly updating the oscillation frequency to a lower frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous oscillation frequency; a third step of updating the oscillation frequency to a starting frequency different from the previous and the one before that starting frequencies, if the oscillation frequency exceeds the lower limit frequency value as a result of performing the second step, then updating the oscillation frequency to a starting frequency different from the previous and the one before that starting frequencies, and repeatedly updating the oscillation frequency to a higher frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous and the one before that oscillation frequencies; a fourth step of updating the oscillation frequency to a starting frequency different from the previous, the one before that, and the one three steps prior, if the oscillation frequency exceeds the upper limit frequency value as a result of performing the third step, then updating the oscillation frequency to a starting frequency different from the previous, the one before that, and the one three steps prior, and repeatedly updating the oscillation frequency to a lower frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous, the one before that, and the one three steps prior; a fifth step of repeating the first to fourth steps; A microwave irradiation device according to a second aspect of the present invention comprises a microwave oscillation unit equipped with a semiconductor oscillator for irradiating microwaves, and a control unit for controlling the operation of the microwave oscillation unit, wherein the control unit stores a hopping table and has a sweep irradiation function that changes the oscillation frequency of microwaves irradiated by the microwave oscillation unit over time based on the hopping table, the interval between the frequencies of continuously irradiated microwaves is set randomly in the hopping table, and the sweep irradiation function changes the oscillation frequency over time with a period within the range of 10 to 300 milliseconds and determines the oscillation frequency using the hopping table. The microwave ripening apparatus according to the present invention comprises a microwave irradiation device, a storage chamber in which food is contained and microwaves are irradiated onto the contained food by the microwave oscillating unit, and a cooler for cooling the air inside the storage chamber. The control unit promotes the ripening of the food by irradiating the storage chamber with microwaves using the microwave oscillating unit while cooling the storage chamber with the cooler. In the microwave aging apparatus described above, the control unit can be configured to continuously or intermittently irradiate the microwave oscillating unit with microwaves for one hour or more while the food is contained in the storage chamber. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a microwave irradiation device and a microwave maturation device that can reduce interference to communications of wireless communication equipment. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of the microwave aging apparatus according to this embodiment. [Figure 2] This is a diagram illustrating the sweep irradiation method used in the reference example. [Figure 3] This is a diagram illustrating the sweep irradiation according to this embodiment. [Figure 4] This is a diagram to explain continuous irradiation. [Figure 5] This is a diagram (part 1) illustrating intermittent irradiation. [Figure 6] This is a diagram (part 2) illustrating intermittent irradiation. [Figure 7] This figure shows the results of a ping-based wireless communication test when sweep irradiation is being performed. [Figure 8] This diagram illustrates sweep irradiation according to another embodiment. [Modes for carrying out the invention]

[0009] An embodiment of the microwave irradiation apparatus according to the present invention will be described with reference to the figures. In particular, in this embodiment, a microwave aging apparatus will be described as an example of the microwave irradiation apparatus according to the present invention, which promotes the maturation of food by irradiating the food object with microwaves while cooling the surface of the food object.

[0010] FIG. 1 is a configuration diagram of a microwave aging device according to the present embodiment. The microwave aging device 1 according to the present embodiment is a device capable of dry aging and wet aging, and can age meats (including processed meat products such as ham), seafood, dairy products such as cheese, beans such as coffee beans, vegetables, fruits, noodles, breads, alcoholic beverages such as wine, fermented foods (including fermented seasonings such as miso and soy sauce), and the like.

[0011] The microwave aging device 1 irradiates microwaves with a frequency around 2.4 to 2.5 GHz to vibrate water molecules contained in food and heat the food. However, wireless communication devices that use the frequency band around 2.4 GHz are also provided in wireless communication, and there has been a problem that the microwaves irradiated by the microwave aging device interfere with the communication of the wireless communication devices. In particular, the microwave aging device 1 according to the present embodiment can be used not only in food factories but also in restaurants and homes. In such places, wireless communication by wireless communication devices is used, so the microwaves irradiated by the microwave aging device interfere with the communication of the wireless communication devices, which becomes a problem. In addition, the microwave aging device 1 may irradiate microwaves for a long time of 1 hour or more for aging, and the wireless communication device may not be able to be used for a long time. In view of such problems, the present invention is characterized by performing sweep irradiation in which the oscillation frequency is switched at regular intervals to irradiate microwaves, thereby reducing the frequency with which the irradiation of microwaves by the microwave aging device interferes with the communication of the wireless communication device.

[0012] FIG. 1 is a configuration diagram of the microwave aging device 1 according to the present embodiment. As shown in FIG. 1, the microwave aging device 1 includes a cooler 10, a refrigerant flow path 20, a microwave oscillation unit 30, an aging chamber 40, a heat insulation unit 50, an internal temperature sensor 60, a control unit 70, a UV lamp 80, and a surface temperature sensor 90.

[0013] As shown in FIG. 1, the cooler 10 is connected to the refrigerant flow path 20 and cools the refrigerant circulating in the refrigerant flow path 20. As the cooler 10, for example, a known device having a compressor, a condenser, etc. and capable of cooling the refrigerant by heat exchange with the outside can be used.

[0014] The refrigerant flow path 20 is connected to the cooler 10, and the refrigerant for cooling the air in the internal space of the aging chamber 40 circulates. The refrigerant flow path 20 is in direct contact with the wall portion 41 of the aging chamber 40. The refrigerant circulating in the refrigerant flow path 20 exchanges heat with the wall portion 41 of the aging chamber 40, so that the wall portion 41 of the aging chamber 40 is cooled, and the air in the aging chamber 40 in contact with the wall portion 41 is cooled. Then, the refrigerant that has exchanged heat and warmed up returns to the cooler 10 again and is cooled by the cooler 10. The refrigerant is not particularly limited, and for example, HFC (hydrofluorocarbon), HC (hydrocarbon), etc. can be used.

[0015] The microwave oscillation unit 30 oscillates microwaves for irradiating the food M. In the present embodiment, a solid-state semiconductor oscillator using a semiconductor element is used as the microwave oscillation unit 30. Compared with a magnetron, the semiconductor oscillator can obtain a high frequency and output stability, and can precisely control the output value and frequency in units of several microseconds. For example, in the semiconductor oscillator, oscillation and stop can be repeated in units of several microseconds, the output value can be changed by several hundred milliwatts (0. several W) in units of several microseconds, or the frequency can be changed by several Hz in units of several microseconds. The microwaves oscillated by the microwave oscillation unit 30 are irradiated into the aging chamber 40 from the irradiation port 42 of the aging chamber 40 via the cable 31.

[0016] Food M to be aged is placed in the aging chamber 40. Microwaves emitted by the microwave oscillator 30 are irradiated into the aging chamber 40 from the irradiation port 42 via the cable 31, uniformly heating the food M placed in the aging chamber 40. In this embodiment, a small, high-gain patch antenna (planar antenna) is attached to the irradiation port 42, so that the microwaves emitted by the microwave oscillator 30 are irradiated into the aging chamber 40. In addition, the refrigerant flow path 20 is in direct contact with the wall 41 of the aging chamber 40 without any gaps, and the refrigerant flowing through the refrigerant flow path 20 cools the wall 41 of the aging chamber 40, and the wall 41 cools the air inside the aging chamber 40 that is in contact with the wall 41, thereby cooling the food M from the surface. This makes it possible to raise the internal temperature of the food M above the surface temperature of the food M.

[0017] Furthermore, as shown in Figure 1, the aging chamber 40 is equipped with a fan 43 and a door (not shown) installed on the inner wall of the aging chamber 40. The fan 43 can be one that can blow air at an airflow suitable for dry aging (for example, 0.5 to 10.0 m / sec). The fan 43 circulates the air inside the aging chamber 40, allowing the cold air cooled by the refrigerant to be directed onto the food M, thereby efficiently cooling the surface of the food M. The door also has a choke structure to prevent microwaves from leaking to the outside and can be opened and closed from the outside. The choke structure can be a known structure. The user can open and close the door to put the food M to be aged into and out of the aging chamber 40. Reflectors for reflecting microwaves are installed on all surfaces of the inner wall 41 of the aging chamber 40. Shelves of any shape made of microwave-permeable material such as Teflon® or polypropylene may be installed in the aging chamber 40. Furthermore, when using metal materials such as stainless steel, you may install grid-like shelves with spacing of 20 mm or more, or perforated metal shelves with openings of 20 mm or more in diameter.

[0018] The heat insulating section 50 is a component that prevents the refrigerant flowing through the refrigerant channel 20 from exchanging heat with the outside air before it reaches the aging chamber 40. As shown in Figure 1, the heat insulating section 50 is in direct contact with the refrigerant channel 20 without any gaps, and together with the wall 41 of the aging chamber 40, it sandwiches the refrigerant channel 20. The material of the heat insulating section 50 is not particularly limited, and for example, expanded polystyrene or urethane can be used.

[0019] The internal temperature sensor 60 measures the internal temperature of the food M. For example, the tip of the internal temperature sensor 60 can be constructed by inserting a pair of thermocouple wires into a metal protective tube, and by inserting the tip into the food M, the internal temperature of the food M can be measured according to the thermoelectric voltage generated at the contact point of the pair of thermocouple wires. In this embodiment, the microwave aging apparatus 1 also has a surface temperature sensor 90 installed on the inner wall of the aging chamber 40 to measure the surface temperature of the food M. As the surface temperature sensor 90, for example, a radiation-type temperature sensor that measures the intensity of infrared rays or visible light by non-contact can be used. Note that the installation location of the surface temperature sensor 90 is not limited to the location shown in the figure, and it can be installed at any location on the inner wall of the aging chamber 40.

[0020] The internal temperature of the food M measured by the internal temperature sensor 60, and / or the surface temperature of the food M measured by the surface temperature sensor 90, are output to the control unit 70. Then, as will be described later, the control unit 70 performs temperature control based on the internal temperature of the food M measured by the internal temperature sensor 60 and the surface temperature of the food M measured by the surface temperature sensor 90.

[0021] The control unit 70 incorporates a program that controls the temperature so that the surface temperature and internal temperature of the food M being aged reach predetermined temperatures. Specifically, the control unit 70 controls the temperature by controlling the operation of the cooler 10, the microwave oscillator 30, and the fan 43, thereby controlling the temperature of the cold air from the cooler 10, the microwave output from the microwave oscillator 30, and the airflow of the fan 43. For example, the control unit 70 can raise the internal temperature of the food M by increasing the microwave output of the microwave oscillator 30, and can lower the surface temperature of the food M by lowering the temperature of the cold air from the cooler 10 or increasing the airflow of the fan 43. For example, by controlling the operation of the microwave oscillator 30, the cooler 10, and the fan 43, the control unit 70 can lower the surface temperature of the food M to below room temperature, and raise the internal temperature of the food M to above the surface temperature of the food M.

[0022] Furthermore, the control unit 70 can control the oscillation of microwaves by the microwave oscillation unit 30. In particular, in this embodiment, the microwave oscillation unit 30 is a semiconductor oscillator, and the oscillation of microwaves can be controlled with high precision. For example, the control unit 70 can be configured to continuously irradiate the food M with microwaves from the microwave oscillation unit 30 for more than one hour, or to irradiate it intermittently for more than one hour, while the food M is contained in the maturation chamber 40. Moreover, in this embodiment, the control unit 70 has a sweep irradiation function that irradiates microwaves while changing the oscillation frequency by controlling the oscillation of microwaves from the microwave oscillation unit 30.

[0023] The sweep irradiation function is an irradiation method in which the microwave oscillation unit 30 oscillates microwaves while changing the frequency over time. When performing sweep irradiation, the control unit 70 can irradiate microwaves while continuously changing the microwave oscillation frequency between 2.40 and 2.50 GHz, for example. Furthermore, the range of the oscillation frequency is not limited to 2.40 to 2.50 GHz; for example, the frequency can be changed in the range of 300 MHz to 300 GHz. Moreover, the range of change in the oscillation frequency is not particularly limited; for example, the oscillation frequency can be changed every few Hz to several GHz. By irradiating microwaves while changing the microwave oscillation frequency through sweep irradiation, the distribution of the electromagnetic field in the maturation chamber 40 is made uniform, so that microwaves are irradiated to the food M with a uniform distribution, promoting uniform heating (uniform maturation) of the food M.

[0024] In the IEEE 802.11b (2.4GHz) wireless LAN standard, 14 channels are set within a 95MHz frequency band from 2401MHz to 2495MHz. According to this, each channel has a bandwidth of 22MHz, and they are set with a 5MHz shift and overlap with each other. Specifically, channel 1 is a 22MHz band from 2401 to 2423MHz centered at 2412MHz, channel 2 is a 22MHz band from 2406 to 2428MHz centered at 2417MHz, channel 3 is a 22MHz band from 2411 to 2433MHz centered at 2422MHz, channel 4 is a 22MHz band from 2416 to 2438MHz centered at 2427MHz, and so on up to channel 13. Channel 14 is a 22MHz band from 2473 to 2495MHz centered at 2484MHz. Thus, 14 channels are set in the frequency band from 2401MHz to 2495MHz. Wireless communication devices use one of these channels to communicate. However, if, for example, a wireless communication device is using channel 1, and the microwave aging device 1 irradiates microwaves at an oscillation frequency in the 2401-2423MHz frequency band corresponding to channel 1, the microwave aging device 1 will interfere with the wireless communication device's communication, causing it to be disrupted.

[0025] Therefore, in this embodiment, the control unit 70 changes the microwave oscillation frequency in the sweep irradiation in the following manner. The method for changing the frequency in the sweep irradiation according to this embodiment will be explained below with reference to Figures 2 and 3. Figure 2 is a diagram for explaining a sweep irradiation method according to a reference example, and Figure 3 is a diagram for explaining the sweep irradiation method according to this embodiment.

[0026] In the microwave aging apparatus described in the reference example, as shown in Figure 2, microwaves were irradiated by sweeping a 95 MHz frequency band from 2401 MHz to 2495 MHz, continuously increasing the frequency by 1 MHz at a 1-second period. Hereafter, the amount by which the frequency is changed in one sweep irradiation is referred to as the frequency change amount, and the period during which the frequency is changed in the sweep irradiation is referred to as the sweep period. Furthermore, in the microwave aging apparatus described in the reference example, the frequency was continuously changed to a higher frequency at a sweep speed of 1 MHz / second, and when it exceeded 2495 MHz, it was returned to 2401 MHz, and then the frequency was changed again from 2401 MHz by 1 MHz at a 1-second period. With such sweep irradiation, it took 22 seconds to pass through one 22 MHz channel, resulting in the problem of interference with the communication of wireless communication devices.

[0027] In contrast, in this embodiment, instead of using the entire 95MHz frequency band from 2401MHz to 2495MHz, 2421MHz is set as the lower limit frequency value (sweep start value), which is the lowest frequency value in the frequency band used for sweep irradiation, and 2480MHz is set as the upper limit frequency value, which is the highest oscillation frequency value in the frequency band used for sweep irradiation. By setting 2421MHz as the lower limit frequency value in this way, a large portion of the frequency band of one channel, which is used relatively frequently in wireless communication devices, can be excluded from the transmission frequency, thereby reducing interference with the communication of wireless communication devices. Furthermore, in this embodiment, sweep irradiation is performed while increasing the oscillation frequency by a predetermined value greater than 3MHz within the range from the lower limit frequency value to the upper limit frequency value. Specifically, as shown in Figure 3, the control unit 70 performs sweep irradiation, continuously changing the frequency from 2421MHz to a higher frequency by a change of 9MHz, using a preset frequency band of 59MHz from 2421MHz to 2480MHz, with a sweep speed of 36MHz / second (9MHz / 250ms) where the frequency change amount is 9MHz and the sweep period is 250ms.

[0028] Furthermore, in this embodiment, microwaves are irradiated while gradually changing the oscillation frequency of the microwave oscillator 30 to a higher frequency in the frequency band from the upper frequency limit to the lower frequency limit. If the microwave frequency after the change exceeds the upper frequency limit, the frequency obtained by adding the amount exceeding the upper frequency limit to the lower frequency limit is set as the starting frequency for the next cycle, and the sweep irradiation for the next cycle is started from the set starting frequency. In Figure 3, the starting frequencies for each cycle are indicated by gray circles.

[0029] Specifically, as shown in Figure 3, the control unit 70 sets the lower limit frequency value, 2421MHz, as the starting frequency in the first cycle. The control unit 70 then changes the oscillation frequency with a sweep period of 250 milliseconds and a change amount of 9MHz. For example, in the example shown in Figure 3, the control unit 70 changes the oscillation frequency over time to 2421MHz, 2430MHz, 2439MHz, 2448MHz, 2457MHz, 2466MHz, and 2475MHz in the first cycle with a period of 250 milliseconds. If, after changing the oscillation frequency to 2475MHz in the first cycle, it were to be changed to 2484MHz (2475MHz + 9MHz), the upper limit frequency value of 2480MHz would be exceeded by 4MHz. Therefore, in this case, the control unit 70 sets the starting frequency for the second cycle and starts the sweep irradiation of the second cycle from the set starting frequency. Specifically, the control unit 70 sets the starting frequency for the second cycle to 2425MHz, which is the lower limit frequency value of 2421MHz plus 4MHz that exceeds the upper limit frequency value of 2480MHz. Then, in the second cycle, the control unit 70 starts from the starting frequency of 2425MHz and changes the oscillation frequency with a sweep period of 250 milliseconds and a change amount of 9MHz. If the frequency exceeds the upper limit frequency value of 2480MHz, it similarly sets the starting frequency for the third sweep irradiation and performs the third sweep irradiation.

[0030] Thus, in this embodiment, the control unit 70 sets the starting frequency to a different starting frequency than the previous one when the oscillation frequency is changed over time and exceeds the upper frequency limit. For example, in the example shown in Figure 3, the starting frequency for the first cycle is set to 2421MHz, the starting frequency for the second cycle is set to 2425MHz, the starting frequency for the third cycle is set to 2429MHz, the starting frequency for the fourth cycle is set to 2424MHz, the starting frequency for the fifth cycle is set to 2428MHz, the starting frequency for the sixth cycle is set to 2423MHz, the starting frequency for the seventh cycle is set to 2427MHz, the starting frequency for the eighth cycle is set to 2422MHz, and the starting frequency for the ninth cycle is set to 2426MHz. In this way, in this embodiment, sweep irradiation is performed so that the starting frequency is not set to the same value consecutively. In the example shown in Figure 3, the starting frequency is the same value only in the tenth cycle, and from the tenth cycle onward, the oscillation frequency sweep is repeated in the same way as in the first to ninth cycles.

[0031] In addition, in this embodiment, the control unit 70 sets the value of the frequency band for changing the microwave as a prime number. In other words, the control unit 70 sets the frequency band such that the value obtained by subtracting the lower frequency limit from the upper frequency limit is a prime number. For example, the control unit 70 is configured to change the oscillation frequency in a frequency band of 59 MHz, where the upper frequency limit is 2421 MHz and the lower frequency limit is 2480 MHz. In this case, the frequency band will be a prime number of 59 MHz. Note that the width of the frequency band is not limited to 59 MHz as long as it is a prime number, and can be, for example, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 61, 67, 71, 79, 83, 89, 97 MHz, etc.

[0032] Furthermore, when the control unit 70 changes the oscillation frequency, it increases the oscillation frequency by a predetermined value. As mentioned above, in the wireless communication equipment standard, one channel is 22 MHz, and if the frequency remains in the same channel for a long time, it will interfere with communication on that channel. Therefore, the amount of change when changing the frequency is preferably 3 to 20 MHz, and more preferably 5 to 20 MHz. The control unit 70 also changes the microwave oscillation frequency with a period of 500 milliseconds or less, preferably 10 to 300 milliseconds. In addition, the control unit 70 performs sweep irradiation with a sweep speed of 20 MHz / second or more, more preferably 30 MHz / second or more, to prevent the oscillation frequency from remaining in the same channel for a long time. When the sweep speed is 30 MHz / second or more, the residence time of the microwave oscillation frequency in one channel can be made less than 1 second (0.73 seconds if it is 30 MHz / second). In this embodiment, the change in oscillation frequency is set to 9 MHz, and the oscillation frequency sweep period is 250 milliseconds, resulting in sweep irradiation at a sweep speed of 36 MHz / second (9 MHz / 250 milliseconds).

[0033] Furthermore, in this embodiment, the control unit 70 may be configured to perform fixed irradiation, continuous irradiation, or intermittent irradiation in addition to the sweep irradiation described above. Fixed irradiation is an irradiation method in which the microwave oscillator 30 is fixed to a constant output value and a constant frequency and oscillates.

[0034] Furthermore, continuous irradiation is an irradiation method in which the microwave oscillator 30 emits microwaves while changing the output value over time. Here, Figure 4 is a diagram illustrating continuous irradiation in which the output value of the microwave oscillator 30 is changed over time. When performing continuous irradiation, the control unit 70 can perform continuous irradiation by emitting microwaves while changing the output value of the microwave oscillator 30 in increments of 0.2W every 2 milliseconds, as shown in Figure 2, for example. The range of change in the output value is not particularly limited, and the output value can be changed in increments of several milliwatts to several watts. Furthermore, the time interval for changing the output value is not particularly limited, and the output value can be changed every few milliseconds to several hours. The control unit 70 can determine the rise and fall of the output value of the microwave oscillator 30 based on the measurement results of the internal temperature sensor 60. In addition, although the maximum output value of the microwave oscillator 30 in continuous irradiation is set to 50W in this embodiment, it is not limited to this, and can be any output value of 100W or less.

[0035] Intermittent irradiation is an irradiation method in which the microwave oscillator 30 repeatedly oscillates and stops at short intervals (for example, a few milliseconds). Figures 5 and 6 are diagrams illustrating intermittent irradiation. In intermittent irradiation, the maximum output value can be arbitrarily set up to 100W, and the interval can also be arbitrarily set from a few milliseconds to a few hours. In the example shown in Figure 5, the interval is set to 2 milliseconds, and the oscillation time in one interval is controlled in units of approximately 7.8 microseconds (1 / 256 of the interval). In this case, the oscillation time in one interval can be variable and will be approximately 7.8 microseconds × N (where N is an integer). In the example shown in Figure 6, the interval is set to 1 second, and the oscillation time in one interval is controlled in units of approximately 1 millisecond. In this case, the oscillation time in one interval will be approximately 1 millisecond × N (where N is an integer). The control unit 70 can also set the oscillation time in one interval by setting the duty cycle.

[0036] Thus, the control unit 70 can be configured to perform fixed irradiation, continuous irradiation, or intermittent irradiation in addition to sweep irradiation. For example, it can be configured to switch between sweep irradiation and fixed irradiation, continuous irradiation, or intermittent irradiation over time. For example, the control unit 70 can be configured to combine sweep irradiation and continuous irradiation, sweeping the microwave frequency in the range of 2421MHz to 2480MHz, and changing the output value by 0.2W every 2 milliseconds so that the internal temperature of the beef thigh meat reaches 10℃. Alternatively, the control unit 70 can be configured to combine sweep irradiation and intermittent irradiation, sweeping the microwave frequency in the range of 2421MHz to 2480MHz, setting one cycle to 2 milliseconds, and changing the oscillation time in one cycle in units of approximately 7.8 microseconds (1 / 256 of the period) to irradiate with microwaves. Furthermore, when performing continuous or intermittent irradiation, the control unit 70 can be configured to combine continuous and intermittent irradiation, changing the output value in increments of 0.2W every 2 milliseconds, setting one cycle to 2 milliseconds, and changing the oscillation time in one cycle in units of approximately 7.8 microseconds (1 / 256 of the cycle) to irradiate with microwaves. In addition, the control unit 70 can be configured to combine continuous and intermittent irradiation, changing the output value in increments of 0.2W every few to tens of milliseconds, setting one cycle to several to tens of milliseconds, and further controlling the oscillation time in one cycle in units of approximately 1 millisecond, and by setting the duty cycle, the oscillation time of the microwave oscillator 30 in one cycle can be set to irradiate with microwaves.

[0037] Furthermore, the control unit 70 can be configured to control the microwave oscillation unit 30 so as to switch the ON-OFF state of microwave irradiation at regular intervals (for example, every few hours) (in the case of intermittent irradiation, to switch between periods of intermittent irradiation and periods of long-term oscillation suspension at regular intervals). For example, the control unit 70 can control the microwave oscillation unit 30 so as to irradiate with microwaves for 3 hours, then stop the microwave irradiation for 3 hours, and similarly repeat the cycle of microwave irradiation and suspension every 3 hours, for example, throughout the 7-day maturation period.

[0038] When food M is aged by irradiating it with microwaves in this manner, the microwaves heat the inside of the food through dielectric heating, so the inside of the food M can be heated in addition to the surface of the food M. Normally, heating the inside of the food M can accelerate the aging of the food M, but heating the surface of the food M promotes the growth of bacteria attached to the surface of the food M. In contrast, in the microwave aging apparatus 1 according to this embodiment, the growth of bacteria attached to the surface of the food M can be suppressed by cooling the surface of the food M through the operation of the cooling mechanism, i.e., the cooler 10 and the fan 43.

[0039] In particular, in the microwave aging apparatus 1 according to this embodiment, the operation of the heating mechanism (microwave oscillation unit 30) and the cooling mechanism (cooler 10 and fan 43) is controlled by the control unit 70 so that the surface temperature of the food M is lower than the internal temperature. Specifically, the control unit 70 controls the temperature of the cold air from the cooler 10, the output of the microwave oscillation unit 30, and the airflow from the fan 43 so that the surface temperature of the food M is lower than the internal temperature. It is not necessary to continuously irradiate the food M with microwaves throughout the aging process; the microwave irradiation can be performed for at least 1 hour (preferably 3 hours or more, more preferably 5 hours or more).

[0040] The UV lamp 80 is a device that generates ultraviolet light. In this embodiment, by directly installing the UV lamp inside the maturation chamber 40, the ultraviolet light generated by the UV lamp 80 can be irradiated onto the surface of the food M placed inside the maturation chamber 40 during the maturation of the food M. In this way, by directly irradiating the surface of the food M with ultraviolet light during maturation, the growth of bacteria present on the surface of the food M can be further suppressed. The control unit 70 can also control the operation of the UV lamp 80. For example, the control unit 70 can control the UV lamp 80 to irradiate with ultraviolet light for a certain period of time (for example, several hours) from the time when maturation begins or when the door of the maturation chamber 40 is closed (after being opened). [Examples]

[0041] (Example 1) Next, Example 1 of the microwave aging apparatus 1 according to this embodiment will be described. A Wi-Fi® router, a Wi-Fi-enabled laptop, and a microwave aging device 1 were installed in the same room, and the occurrence of communication problems was verified. The laptop was connected to the SSID (2.4GHz band) provided by the Wi-Fi router via DHCP. The Wi-Fi® connection type used by the laptop and the Wi-Fi router was set to "IEEE802.11b / g / n" automatic configuration.

[0042] In Example 1, the sweep irradiation using the microwave aging apparatus 1 was performed as follows. Specifically, a frequency band of 59 MHz from 2421 MHz to 2480 MHz was continuously changed from 2421 MHz to a higher frequency with a sweep period of 250 milliseconds and a change amount of 9 MHz (sweep speed 9 MHz / 250 milliseconds). If the frequency exceeded the upper limit frequency value of 2480 MHz, the starting frequency was set to the lower limit frequency value of 2421 MHz plus the value exceeding the upper limit frequency value (for example, 2425 MHz for the second cycle), and the sweep irradiation was performed again by changing to a higher frequency with a sweep period of 250 milliseconds and a change amount of 9 MHz. During this sweep irradiation, a 1 KB ping command was transmitted 10 times using a wireless communication device, and it was observed whether the wireless communication was successful or not. As a result, in Example 1, the wireless communication for all 10 ping commands was successful. Ping is a command that sends an ICMP (Internet Control Message Protocol) echo request packet to a destination host and verifies the reachability of the communication by receiving an echo reply from the destination host.

[0043] (Comparative Example 1) In Comparative Example 1, the same Wi-Fi® router, laptop computer, and microwave aging apparatus 1 as in Example 1 were used. In the frequency band from 2421MHz to 2480MHz, the frequency was changed from 2421MHz to a higher frequency with a sweep period of 1 second and a change amount of 1MHz (sweep speed of 1MHz / second). If the frequency exceeded 2480MHz, it was returned to 2421MHz, and then changed again from 2421MHz to a higher frequency with a sweep period of 1 second and a change amount of 1MHz. During this sweep irradiation, a 1KB ping command was transmitted 10 times using a wireless communication device, and it was observed whether the wireless communication was successful or not. As a result, in Comparative Example 1, the wireless communication for all 10 ping commands failed.

[0044] Figure 7 shows the test results for Example 1 and Comparative Example 1, as well as the test results for wireless communication using ping at other frequency changes and frequency sweep periods. In the examples shown in Figure 7, the sweep irradiation was performed in the same manner as in Example 1 and Comparative Example 1, except that the frequency changes were 1, 2, 3, 5, 7, 9, 12, and 20 MHz, and the sweep periods were 10, 50, 100, 200, 250, 300, and 1000 milliseconds, respectively. Then, as in Example 1 and Comparative Example 1, a 1KB ping command was transmitted 10 times from the wireless communication device during the sweep irradiation, and it was observed whether wireless communication was successful or not. In the examples shown in Figure 7, "○" indicates that communication was successful all 10 times the ping command was executed, "△" indicates that communication was successful some of the time the ping command was executed, and "×" indicates that communication failed all 10 times the ping command was executed. "-" indicates a combination that was not tested.

[0045] As shown in Figure 7, when the frequency sweep period was set to 1000 milliseconds, the wireless communication device tended to fail to communicate wirelessly, indicating that the microwave irradiation from the microwave aging apparatus 1 interfered with the wireless communication of the wireless communication device. On the other hand, when the frequency sweep period was set to a range of 10 to 300 milliseconds, interference with wireless communication tended to improve. Furthermore, when the frequency change amount was set to 1 or 2 MHz, communication of the ping command failed even when the frequency sweep period was set to 100 milliseconds, indicating that it is preferable to set the frequency change amount to 3 to 20 MHz or more.

[0046] As described above, from Example 1, Comparative Example 2, and the example in Figure 7, it was found that interference to wireless communication can be reduced by setting the frequency sweep period to within the range of 10 to 300 milliseconds and performing sweep irradiation with a starting frequency different from the previous frequency. Furthermore, it was found that interference to wireless communication can be further reduced by setting the frequency change per step in sweep irradiation to 3 to 20 MHz or more. In particular, by setting the conditions above the dashed line shown in Figure 7, specifically the sweep speed to 20 MHz / second or more, interference to wireless communication can be significantly reduced, and wireless communication of wireless communication devices can be performed smoothly.

[0047] (Example 2) In Example 2, a 59MHz frequency band from 2421MHz to 2480MHz was swept upwards from 2421MHz with a sweep period of 250ms and a change of 10MHz (sweep speed 10MHz / 250ms). If the frequency exceeded the upper limit of 2480MHz, the starting frequency was set to the lower limit of 2421MHz plus the frequency exceeding the upper limit (for example, 2426MHz for the second cycle), and the sweep irradiation was performed again with a sweep period of 250ms and a change of 10MHz. During this sweep irradiation, a 2MB file was transmitted using the TCP / IP protocol via a wireless communication device, and it was observed whether wireless communication was possible. As a result, it was confirmed that the 2MB file could be transmitted without problems in Example 2, and that the impact on Wi-Fi communication was significantly reduced. The hardware environment for Example 2 was the same as in Example 1.

[0048] (Example 3) In Example 3, a 59MHz frequency band from 2421MHz to 2480MHz was swept up from 2421MHz with a sweep period of 4 milliseconds and a change of 1MHz (sweeping at a speed of 1MHz / 4 milliseconds). When the frequency exceeded the upper frequency limit of 2480MHz, it returned to the lower frequency limit of 2421MHz and was again swept up to a higher frequency with a sweep period of 4 milliseconds and a change of 1MHz. During this sweep irradiation, 1MB and 2MB files were transmitted via TCP / IP communication using a wireless communication device, and it was observed whether wireless communication was possible. As a result, in Example 3, it was confirmed that even when the sweep period was shortened to 4 milliseconds, which is shorter than the 250 millisecond sweep period in Example 2, 1MB and 2MB files could be transmitted, and the impact on WiFi communication could be reduced. The hardware environment for Example 3 was the same as in Example 1.

[0049] As described above, the microwave aging apparatus 1 according to this embodiment includes a microwave oscillation unit 30 that irradiates microwaves and a control unit 70 that controls the operation of the microwave oscillation unit 30. The control unit 70 has a sweep irradiation function that irradiates microwaves while changing the oscillation frequency of the microwave oscillation unit 30 over time from a starting frequency to a higher frequency within a range from a set upper frequency limit to a lower frequency limit. The sweep irradiation function performs the change in oscillation frequency over time with a period of 10 to 300 milliseconds and includes a function to set a different starting frequency from the previous one if the change in oscillation frequency over time would exceed the upper frequency limit. As a result, in the microwave aging apparatus 1 according to this embodiment, it is possible to prevent the oscillation frequency from remaining in the same communication channel frequency band for a long time during sweep irradiation, and to prevent microwaves from being repeatedly irradiated at the same oscillation frequency with each cycle, thereby reducing interference to wireless communication devices. Furthermore, in the microwave aging apparatus 1 according to this embodiment, since microwaves are not repeatedly irradiated at the same oscillation frequency with each rotation, the frequency of the irradiated microwaves is not biased, which can contribute to the uniform heating of the food.

[0050] Although preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the embodiments described above. Various modifications and improvements can be made to the above embodiments, and such modified or improved forms are also included in the technical scope of the present invention.

[0051] For example, in the embodiment described above, a configuration was illustrated in which microwaves are irradiated while the oscillation frequency of the microwave oscillation unit 30 is changed over time from the starting frequency to a higher frequency by the sweep irradiation function. However, the configuration is not limited to this, and a configuration can be made in which microwaves are irradiated while the oscillation frequency of the microwave oscillation unit 30 is changed over time from the starting frequency to a lower frequency by the sweep irradiation function. In this case, if the microwave frequency after the change exceeds the lower limit frequency value, the starting frequency can be returned to near the upper limit frequency value, and the oscillation frequency of the microwave oscillation unit 30 can be changed over time again towards the lower limit frequency.

[0052] Furthermore, in the embodiment described above, as shown in Figure 8, the control unit 70 increases the oscillation frequency over time by a change of 9 MHz from the starting frequency, and if the oscillation frequency exceeds the upper limit frequency value, the frequency obtained by adding the frequency exceeding the upper limit frequency value to the lower limit frequency value is set as the starting frequency for the second cycle and beyond. However, the sweep method is not limited to this, and a configuration that performs sweep irradiation as shown in Figure 8 is also possible. In other words, as shown in Figure 8, the control unit 70 sets the starting frequency for the first cycle to 2421 MHz, which is the lower limit frequency value. The control unit 70 then changes the oscillation frequency in the direction of increasing frequency with a sweep period of 250 milliseconds and a change amount of 9 MHz. If, after changing the oscillation frequency to 2475 MHz in the first cycle, it were to be changed to 2484 MHz (2475 MHz plus 9 MHz), the upper limit frequency value of 2480 MHz would be exceeded by 4 MHz. Therefore, in this case, the control unit 70 sets the starting frequency for the second cycle and starts the sweep irradiation for the second cycle from the set starting frequency.

[0053] In the example shown in Figure 8, the control unit 70 sets the starting frequency for the second cycle to 2476MHz, which is obtained by subtracting the 4MHz exceeding the upper frequency limit of 2480MHz from the upper frequency limit of 2480MHz. Then, in the second cycle, the control unit 70 starts from the starting frequency of 2476MHz and changes the oscillation frequency in the direction of decreasing frequency with a sweep period of 250 milliseconds and a change amount of 9MHz. For example, in the example shown in Figure 8, in the second cycle, the control unit 70 changes the oscillation frequency over time to 2476MHz, 2467MHz, 2458MHz, 2449MHz, 2440MHz, 2431MHz, and 2422MHz with a sweep period of 250 milliseconds. Then, if the control unit 70 exceeds the lower limit frequency value of 2421MHz, it sets the starting frequency for the third cycle to 2429MHz, which is the lower limit frequency value of 2421MHz plus the frequency exceeding the lower limit value of 8MHz. For the third cycle, it changes the oscillation frequency over time from the starting frequency of 2429MHz in the direction of increasing frequency. In this way, in the example shown in Figure 8, the control unit 70 can perform sweep irradiation with different starting frequencies up to the ninth cycle. Furthermore, in the tenth cycle, the control unit 70 may be configured to return to the first cycle, or it may be configured to set the starting frequency for the tenth cycle to 2480MHz (the last frequency of the ninth cycle, 2480MHz + the frequency exceeding the upper limit frequency value in the ninth cycle, 0MHz), and sweep the frequencies from the ninth cycle to the first cycle in the opposite direction to before.

[0054] Furthermore, in the example shown in Figure 8, if the oscillation frequency exceeds the range of the upper frequency value by changing it over time in the direction of increasing frequency, the starting frequency is set to the upper frequency value minus the frequency exceeding the upper frequency value, and a first sweep (sweeps in weeks 2, 4, 6, and 8 shown in Figure 8) is performed in which the oscillation frequency changes over time in the direction of decreasing frequency from the starting frequency, and after the first sweep, if the oscillation frequency exceeds the range of the lower frequency value by changing it over time in the direction of decreasing frequency, the starting frequency is set to the lower frequency value plus the frequency exceeding the lower frequency value, and a second sweep ( Figure 8 illustrates a configuration in which sweeps are performed in weeks 1, 3, 5, and 7. However, the configuration is not limited to this. If the oscillation frequency exceeds the upper limit frequency range due to the frequency increasing over time, a first sweep can be performed by simply setting a frequency that does not overlap with the frequency updated in the previous or predetermined cycle as the starting frequency, and changing the oscillation frequency from the starting frequency in the frequency decreasing direction over time. If, after the first sweep, the oscillation frequency exceeds the lower limit frequency range, a second sweep can be performed by setting a frequency that does not overlap with the frequency updated in the previous or predetermined cycle as the starting frequency, and changing the oscillation frequency from the starting frequency in the frequency increasing direction over time. For example, in this case, in the second cycle, any frequency that was not updated as the oscillation frequency in the first cycle can be set as the starting frequency. For example, if the first cycle is performed in the example shown in Figure 8, 2467MHz or 2477MHz can be set as the starting frequency for the second cycle. Similarly, in the third cycle, any frequency that was not irradiated in the first and second cycles can be set as the starting frequency.

[0055] Furthermore, in the above-described embodiment, when the oscillation frequency exceeds the range of the upper frequency value due to the change in the oscillation frequency over time, a configuration is shown in which the frequency exceeding the upper frequency value is added to the lower frequency value to set a different starting frequency than the previous time. However, the configuration is not limited to this, and the control unit 70 can store a hopping table, and the frequency of the microwaves oscillated by the microwave oscillation unit can be changed over time based on the hopping table. The hopping table is a frequency table in which frequencies are set randomly using pseudo-random numbers. By using the hopping table, frequency sweeps can be performed at unspecified intervals rather than fixed intervals, so that there can be a large variation in the oscillation frequency, which reduces interference to wireless communication of wireless communication devices and also enables uniform heating. The control unit 70 can be configured to select frequencies registered in the hopping table in descending order, ascending order, or randomly and oscillate them. Furthermore, in the hopping table, the number of frequencies to be registered can be set as appropriate, such as 30 or 60. It is also possible to reuse the same hopping table, or to create a new, different hopping table after all the frequencies registered in the hopping table have been selected.

[0056] Furthermore, in the above-described embodiment, when the frequency obtained by changing the oscillation frequency exceeds the upper frequency value, a configuration was exemplified in which the starting frequency for the next cycle is set to the lower frequency value plus the frequency exceeding the upper frequency value. However, the configuration is not limited to this, and when the frequency obtained by changing the oscillation frequency exceeds the upper frequency value, a configuration can be used in which the starting frequency for the next cycle is set to the lower frequency value plus the cycle number (or cycle number - 1). In this case, for the first cycle, the starting frequency will be the lower frequency value of 2421MHz, and for the second cycle, the starting frequency will be set to 2422MHz, which is the lower frequency value of 2421MHz plus 1 (second cycle - 1). Also, for the 10th cycle and beyond, the last digit can be used as the cycle number. [Explanation of Symbols]

[0057] 1…Microwave aging apparatus 10...Cooler 20… Refrigerant flow path 30...Microwave Oscillator 31… Cable 40…Aging Room 41...Wall part 42... Irradiation port 43...fan 50…Insulation section 60...Internal temperature sensor 70... Control Unit 80... UV lamp 90... Surface temperature sensor

Claims

1. A microwave oscillator equipped with a semiconductor oscillator that irradiates microwaves, The system includes a control unit that controls the operation of the microwave oscillator, The control unit is equipped with a sweep irradiation function that irradiates microwaves while changing the oscillation frequency of the microwave oscillator over time from the starting frequency to a higher or lower frequency within a range from a set upper frequency limit to a lower frequency limit, The sweep irradiation function includes a function that sets the sweep period of the oscillation frequency to a period within the range of 10 to 300 milliseconds, and sets a different starting frequency from the previous one when the oscillation frequency exceeds the range of the upper or lower frequency limit due to the change in the oscillation frequency over time.

2. The microwave irradiation apparatus according to claim 1, wherein the sweep irradiation function changes the oscillation frequency over time by setting the change in the oscillation frequency per unit time to 20 MHz / second or more.

3. The sweep irradiation function described above is If the oscillation frequency exceeds the upper frequency value by changing it over time in the direction of increasing frequency, the starting frequency is set to the lower frequency value plus the frequency exceeding the upper frequency value, or The microwave irradiation apparatus according to claim 1, wherein, if the oscillation frequency exceeds the lower limit frequency value as the oscillation frequency is changed over time in the direction of decreasing frequency, the starting frequency is set to the frequency obtained by subtracting the frequency exceeding the lower limit frequency value from the upper limit frequency value.

4. The sweep irradiation function described above is If changing the oscillation frequency over time in the direction of increasing frequency causes it to exceed the range of the upper frequency limit, the starting frequency is set to the upper frequency limit minus the frequency exceeding the upper frequency limit, and a first sweep is performed in which the oscillation frequency is changed over time from the starting frequency in the direction of decreasing frequency. The microwave irradiation apparatus according to claim 1, wherein, after performing the first sweep, if the oscillation frequency exceeds the range of the lower limit frequency value by changing the oscillation frequency over time in the direction of decreasing frequency, the starting frequency is set to the lower limit frequency value plus the frequency exceeding the lower limit frequency value, and a second sweep is performed in which the oscillation frequency is changed over time from the starting frequency in the direction of increasing frequency.

5. The microwave irradiation apparatus according to claim 1, wherein the value obtained by subtracting the lower frequency limit from the upper frequency limit is a prime number.

6. The microwave irradiation apparatus according to claim 1, wherein the upper limit frequency value and the lower limit frequency value are set within the range of 2400 to 2500 MHz.

7. The microwave irradiation apparatus according to claim 6, wherein the lower limit frequency value is set to 2420 MHz or higher.

8. The microwave irradiation device according to claim 1, wherein the sweep irradiation function continuously increases the oscillation frequency in intervals of 3 to 20 MHz.

9. The microwave irradiation apparatus according to claim 1, wherein the sweep irradiation function includes each of the following steps (A), (B), or (C). (A) A first step in which the oscillation frequency is repeatedly updated to a higher frequency by a predetermined amount of change from the starting frequency, If the oscillation frequency exceeds the upper limit frequency value as a result of performing the first step, the second step involves updating the oscillation frequency to a starting frequency different from the previous starting frequency, and repeatedly updating the oscillation frequency to a higher frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous oscillation frequency. If, as a result of performing the second step, the oscillation frequency exceeds the upper limit frequency value, the oscillation frequency is updated to a starting frequency different from the previous and the one before that starting frequencies, and the oscillation frequency is repeatedly updated to a higher frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous and the one before that oscillation frequencies. A fourth step which repeats the first to third steps described above. (B) A first step in which the oscillation frequency is repeatedly updated to a lower frequency by a predetermined amount from the starting frequency, If, as a result of performing the first step, the oscillation frequency exceeds the lower limit frequency value, the second step involves updating the oscillation frequency to a starting frequency different from the previous starting frequency, and repeatedly updating the oscillation frequency from the updated starting frequency to a lower frequency by a predetermined amount, thereby oscillating at a frequency that does not overlap with the previous oscillation frequency. If, as a result of performing the second step, the oscillation frequency exceeds the lower limit frequency value, the oscillation frequency is updated to a starting frequency different from the previous and the one before that starting frequencies, and the oscillation frequency is repeatedly updated from the updated starting frequency to a lower frequency by a predetermined amount, thereby performing oscillation at a frequency that does not overlap with the previous and the one before that oscillation frequencies. A fourth step which repeats the first to third steps described above. (C) A first step in which the oscillation frequency is repeatedly updated to a higher frequency by a predetermined amount of change from the starting frequency, If, as a result of performing the first step, the oscillation frequency exceeds the upper limit frequency value, the second step involves updating the oscillation frequency to a starting frequency different from the previous starting frequency, and repeatedly updating the oscillation frequency from the updated starting frequency to a lower frequency by a predetermined amount, thereby oscillating at a frequency that does not overlap with the previous oscillation frequency. If, as a result of performing the second step, the oscillation frequency exceeds the lower limit frequency value, the oscillation frequency is updated to a starting frequency different from the previous and the one before that starting frequencies, and the oscillation frequency is repeatedly updated to a higher frequency by a predetermined amount from the updated starting frequency, thereby oscillating at a frequency that does not overlap with the previous and the one before that oscillation frequencies. If the oscillation frequency exceeds the upper limit frequency value as a result of performing the third step, the fourth step involves updating the oscillation frequency to a starting frequency different from the previous, the one before that, and the one three steps prior, and repeatedly updating the oscillation frequency to a lower frequency by a predetermined amount from the updated starting frequency, thereby performing oscillation at a frequency that does not overlap with the previous, the one before that, and the one three steps prior. A fifth step which repeats the first to fourth steps described above.

10. A microwave oscillator equipped with a semiconductor oscillator that irradiates microwaves, The system includes a control unit that controls the operation of the microwave oscillator, The control unit stores a hopping table and has a sweep irradiation function that changes the oscillation frequency of the microwaves emitted by the microwave oscillation unit over time based on the hopping table. In the aforementioned hopping table, the intervals between the frequencies of the continuously irradiated microwaves are set randomly. The sweep irradiation function is a microwave irradiation device that changes the oscillation frequency over time with a period within the range of 10 to 300 milliseconds and determines the oscillation frequency using the hopping table.

11. A microwave irradiation apparatus according to any one of claims 1 to 10, A storage chamber in which food is contained and microwaves are irradiated onto the contained food by the microwave oscillating unit, It has a cooler for cooling the air inside the containment chamber, The control unit promotes the maturation of food by irradiating the storage chamber with microwaves using the microwave oscillation unit while cooling the storage chamber with the cooler.

12. The microwave aging apparatus according to claim 11, wherein the control unit irradiates the microwave oscillating unit with microwaves continuously or intermittently for one hour or more while the food is contained in the storage chamber.

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