Microwave heating device

Abstract

The chirp signal generation device includes a control unit (111) that sets chirp parameters for multiple types of microwave band chirp signals having different chirp inclinations, including a first chirp signal and a second chirp signal, and a chirp signal generator (112) that generates multiple types of microwave band chirp signals according to the set chirp parameters and outputs the generated chirp signals to different transmission lines.

Description

[Technical Field]

[0001] This disclosure relates to chirp signal generation and radiation techniques, as well as microwave heating techniques. [Background technology]

[0002] Patent Document 1 discloses a microwave utilization device that enables uniform heating of an object to be heated and includes a heating chamber in which an object to be heated is housed, a microwave generating means equipped with a frequency variable function for generating microwaves to be supplied to the heating chamber, at least one pair of radiating means arranged opposite each other to supply microwaves generated from the microwave generating means to the heating chamber, a phase variable switch for varying the phase of microwaves transmitted to each of the pair of radiating means, a power coupler for extracting reflected power from the radiating means, and a control means for controlling the microwave generating means and the phase variable switch. The control means changes the oscillation frequency of the microwave generating means from the lower limit to the upper limit of the frequency variable range in the initial stages of heating, selects the frequency at which the reflected power detected by the power coupler is minimized, and controls the phase variable switch while the microwave generating means is operating at this frequency to variably control the phase difference of microwaves radiated from the pair of radiating means. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4839994 [Overview of the project] [Problems that the invention aims to solve]

[0004] According to the technology described in Patent Document 1, the oscillation frequency is varied from the lower limit to the upper limit of the frequency variable range during the initial heating phase to select the frequency at which the reflected power is minimized. The phase difference of the microwaves is then variably controlled by controlling a phase variable at this frequency. However, this method of searching for the frequency at which the reflected power is minimized has the problem that it requires time to search for the frequency, thus increasing the heating time.

[0005] This disclosure was made to solve such problems and aims to provide a technology that enables uniform and faster heating of an object to be heated. [Means for solving the problem]

[0006] One aspect of a chirp signal generation device according to an embodiment of the present disclosure includes a control unit that sets chirp parameters for a plurality of types of microwave band chirp signals having different chirp inclinations, including a first chirp signal and a second chirp signal, and a chirp signal generator that generates a plurality of types of microwave band chirp signals according to the set chirp parameters and outputs the generated chirp signals to different transmission lines. [Effects of the Invention]

[0007] According to the chirp signal generation device of the embodiment of the present disclosure, it is possible to output chirp signals of multiple types of microwave bands, thereby enabling uniform and faster heating of the object to be heated. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example configuration of a microwave heating apparatus according to Embodiment 1. [Figure 2A] This figure shows an example of the hardware configuration of the control unit. [Figure 2B] This figure shows an example of the hardware configuration of the control unit. [Figure 3] This diagram shows an example configuration of a chirp signal generator. [Figure 4] It is a diagram showing an example of the waveform of a chirp signal. [Figure 5] It is a diagram showing an example of the waveform of a chirp signal. [Figure 6] It is a diagram showing an example of the waveform of a chirp signal. [Figure 7] It is a diagram showing an example of the waveform of a chirp signal. [Figure 8] It is a diagram showing an example of the waveform of a chirp signal. [Figure 9] It is a diagram showing an example of the waveform of a chirp signal. [Figure 10] It is a diagram showing an example of the waveform of a chirp signal. [Figure 11] It is a diagram showing an example of the waveform of a chirp signal.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, various embodiments in the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or similar parts are denoted by the same or similar reference numerals, and duplicate explanations of such parts are omitted. Also, in the present disclosure, the term "or" is used in the sense of an inclusive disjunction unless otherwise specified.

[0010] Embodiment 1. <Configuration> Referring to FIG. 1, a microwave heating device according to Embodiment 1 of the present disclosure will be described. The microwave heating device is a device for irradiating a microwave to an object to be heated, which is an object to be heated, and heating the object to be heated. The microwave may be irradiated for the purpose of drying the object to be heated. Examples of the object to be heated include various objects such as rubber, dried noodles, and malt.

[0011] To achieve this objective, one aspect of the microwave heating apparatus includes a chirp signal emitter 1 and a microwave heating furnace 2, as shown in Figure 1. Figure 1 shows a case where two types of chirp signals are emitted from the chirp signal emitter 1. The object to be heated is placed inside the internal space of the microwave heating furnace 2, and the microwaves generated by the chirp signal emitter 1 are irradiated onto the object, thereby heating it.

[0012] The chirp signal radiator 1 is a device for generating multiple chirp signals in the microwave band and radiating the generated chirp signals. To achieve this purpose, one aspect of the chirp signal radiator 1 includes a chirp signal generator 11, multiple variable-gain power amplifiers 12, and multiple antennas 13. Figure 1 shows an example in which the chirp signal generator 11 generates two pairs of microwave band chirp signals. Note that the chirp signal generator 11 may generate three or more types of chirp signals. In general, the chirp signal generator 11 may generate N types of chirp signals (N is a positive integer of 2 or more), and is equipped with N variable-gain power amplifiers 12 and N antennas 13 depending on the type of chirp signal to be generated.

[0013] The chirp signal generator 11 is a device for generating multiple chirp signals in the microwave band. To achieve this purpose, one aspect of the chirp signal generator 11 includes a control unit 111 and a chirp signal generator 112.

[0014] The following describes in detail the components of the microwave heating device.

[0015] (Control Unit) The control unit 111 is a functional unit that sets chirp parameters for multiple types of microwave band chirp signals, including a first chirp signal and a second chirp signal, each having a different chirp slope, based on user input received via an input device (not shown). Examples of chirp parameters include all or part of the chirp rate, sweep time, bandwidth, sweep start frequency, or sweep end frequency. The chirp rate is the instantaneous rate of change of frequency. If the chirp rate is positive, the chirp slope is positive; if the chirp rate is negative, the chirp slope is negative. The sweep time is the duration of the sweep start time and sweep end time. The bandwidth is the width of the frequency determined by the lower and upper frequencies to be swept. The chirp slope is positive or negative depending on whether the sweep start frequency is the lower or upper frequency. If the sweep start frequency is the lower frequency, the chirp slope is positive; if the sweep start frequency is the upper frequency, the chirp slope is negative. The control unit 111 outputs the set chirp parameter as the control signal S1.

[0016] In addition, the control unit 111 may set the power amplification factor of the generated chirp signal. If a power amplification factor is set, the control unit 111 outputs the power amplification factor as a gain control signal S2 to the variable gain power amplifier 12. The power amplification factor may be a common value for the multiple variable gain power amplifiers 12-1 and 12-2, or it may be a different value for each.

[0017] (Chirp signal generator) The chirp signal generator 112 is a device that generates two or more types of microwave band chirp signals according to chirp parameters set by the control unit 111. The chirp signal generator 112 generates a chirp signal in the microwave band (approximately 300 MHz to 300 GHz) that has been frequency-swept by a predetermined frequency within a predetermined time. The generated chirp signal may be an up-chirp signal in which the frequency increases over time, or a down-chirp signal in which the frequency decreases over time. Since heating can be made more uniform by irradiating the object to be heated with two or more types of chirp signals, the chirp signal generator 112 generates two or more types of microwave band chirp signals.

[0018] The chirp signal generator 112 can be implemented, for example, by a circuit equipped with PLLs (Phase Locked Loops) 1122-1 to 1122-N as shown in Figure 3. N is an integer greater than or equal to 2, corresponding to the number of types of chirp signals to be generated. A reference signal is generated by a reference signal generator 1121, and the generated reference signal is input to PLLs 1122-1 to 1122-N. Each PLL 1122 is equipped with a phase detector, a loop filter, a VCO (Voltage-Controlled Oscillator), and a frequency divider. The frequency divider changes the division ratio over time based on a control signal S1, and the VCO generates the desired chirp signal. By providing multiple PLLs 1122, multiple chirp signals with different chirp parameters can be generated simultaneously.

[0019] The chirp signal generator 112 may be implemented without using a PLL. For example, the chirp signal generator 112 may be configured to include a digital signal processor and an amplifier. More specifically, the chirp signal generator 112 generates a digital microwave signal using a digital signal processor, converts the generated digital microwave signal into an analog microwave signal using a DA converter, applies the analog microwave signal to a diode oscillator circuit to cause the microwave signal to oscillate, and outputs the oscillating microwave signal.

[0020] The chirp signal generator 112 is provided with transmission paths equal in number to the number of types of chirp signals to be generated, and outputs one type of chirp signal via each transmission path.

[0021] Here, referring to FIGS. 4 to 11, examples of waveforms of various chirp signals generated by the chirp signal generator 112 will be described. In FIGS. 4 to 11, the slope of the chirp is defined as the ratio of the difference obtained by subtracting the sweep start frequency (f High ) from the sweep end frequency (f Low ) with respect to the chirp period, or may be grasped as the chirp rate which is the instantaneous change rate of the frequency at a certain time. Hereinafter, the slope of the chirp will be described as the ratio of the difference obtained by subtracting the sweep start frequency (f High ) from the sweep end frequency (f Low ).

[0022] FIG. 4 is a diagram showing examples of a first chirp signal and a second chirp signal. In FIG. 4, the first chirp signal is represented by a solid line, and the second chirp signal is represented by a broken line. An example is shown where the lower limit frequency and the upper limit frequency are common between the first chirp signal and the second chirp signal, and the slopes of the chirps are different. The common lower limit frequency is f Low , and the common upper limit frequency is f High . As is clear from FIG. 4, the slope of the chirp of the first chirp signal is greater than the slope of the chirp of the second chirp signal.

[0023] FIG. 5 is a diagram showing examples of a first chirp signal and a second chirp signal. In FIG. 5, the first chirp signal is represented by a solid line, and the second chirp signal is represented by a broken line. An example is shown where the lower limit frequency, the upper limit frequency, and the slope of the chirp are all different between the first chirp signal and the second chirp signal. The lower limit frequency of the first chirp signal is f’ Low , and the upper limit frequency is f’ High . The lower limit frequency of the second chirp signal is f LowThe upper frequency limit is f High That is the case.

[0024] Figure 6 shows examples of a first chirp signal and a second chirp signal. In Figure 6, the first chirp signal is represented by a solid line, and the second chirp signal is represented by a dashed line. In Figure 6, the lower and upper frequency limits are common to both the first and second chirp signals. Also, in Figure 6, the slope of the chirp in the first chirp signal is negative, and the slope of the chirp in the second chirp signal is positive.

[0025] Figure 7 shows examples of a first chirp signal and a second chirp signal. In Figure 7, the first chirp signal is represented by a solid line, and the second chirp signal is represented by a dashed line. Examples are shown where the lower frequency limit, upper frequency limit, and chirp slope are all different between the first and second chirp signals. Also, in Figure 7, the chirp slope of the first chirp signal is negative, and the chirp slope of the second chirp signal is positive.

[0026] Figure 8 shows examples of a first, second, and third chirp signal. In Figure 8, the first chirp signal is represented by a solid line, the second chirp signal by a dashed line, and the third chirp signal by a dotted line. Figure 8 shows an example where the lower and upper frequency limits are common to the first, second, and third chirp signals, but the chirp slopes are different. As is clear from Figure 8, the chirp slope of the first chirp signal is greater than that of the second chirp signal, and the chirp slope of the second chirp signal is greater than that of the third chirp signal.

[0027] Figure 9 shows examples of the first, second, and third chirp signals. The first chirp signal is represented by a solid line, the second chirp signal by a dashed line, and the third chirp signal by a dotted line. The lower and upper frequency limits differ between the first chirp signal and the second or third chirp signal. The lower frequency limit of the first chirp signal is f'. Low The upper frequency limit is f' High The lower limit frequency of the second or third chirp signal is f. Low The upper frequency limit is f High That is the case.

[0028] Figure 10 shows examples of a first, second, and third chirp signal. The first chirp signal is represented by a solid line, the second chirp signal by a dashed line, and the third chirp signal by a dotted line. In Figure 10, the lower and upper frequency limits are common to the first, second, and third chirp signals. Also in Figure 10, the slope of the chirp in the first chirp signal is negative, while the slopes of the chirps in the second and third chirp signals are positive. The slope of the chirp in the second chirp signal is greater than the slope of the chirp in the third chirp signal.

[0029] Figure 11 shows examples of the first, second, and third chirp signals. The first chirp signal is represented by a solid line, the second chirp signal by a dashed line, and the third chirp signal by a dotted line. The lower and upper frequency limits differ between the first chirp signal and the second or third chirp signal. The lower frequency limit of the first chirp signal is f'. Low The upper frequency limit is f' High The lower limit frequency of the second or third chirp signal is f. Low The upper frequency limit is f High Therefore, the slope of the chirp in the second chirp signal is greater than the slope of the chirp in the third chirp signal.

[0030] Thus, the generated chirp signals can be generated in any bandwidth of the microwave band, as long as the chirp slopes are different. Figures 4 to 11 show examples where the absolute values ​​of the chirp slopes are different from each other.

[0031] Furthermore, although the explanation focused on the case where a single chirp signal is either an up-chirp or a down-chirp, a single chirp signal may also be generated as a signal that combines both up-chirp and down-chirp.

[0032] Furthermore, although the explanation has focused on the case where the chirp signal is a linear chirp, the chirp signal may also be a nonlinear chirp in which the frequency increases or decreases nonlinearly over time.

[0033] (Variable gain power amplifier) The variable-gain power amplifier 12 is an amplifier for variable control of the power of a chirp signal. A variable-gain power amplifier 12 is provided for each chirp signal to be generated. Figure 1 shows an example where two types of chirp signals are generated, and therefore two variable-gain power amplifiers 12-1 and 12-2 are shown. As shown in Figure 1, the variable-gain power amplifier 12 is connected to the control unit 111 and the chirp signal generator 112, and further connected to a power supply (not shown). The variable-gain power amplifier 12 variably amplifies the chirp signal output from the chirp signal generator 112 according to the gain control signal output from the control unit 111, and outputs the amplified chirp signal. By using the variable-gain power amplifier 12 in this way, it becomes possible to dynamically control the power of the chirp signal irradiated according to the attributes of the object to be heated. In the field of object detection, chirp signals are output at a predetermined power, but by using the variable-gain power amplifier 12 as described in this disclosure, heating according to the attributes of the object to be heated becomes possible. The variable-gain power amplifier 12 outputs the power-amplified chirp signal to the antenna 13.

[0034] (antenna) Antenna 13 is a device for irradiating the object to be heated with a power-amplified chirp signal supplied from the variable-gain power amplifier 12. An antenna 13 is provided for each chirp signal to be generated. Figure 1 shows an example where two types of chirp signals are generated, and therefore two antennas 13-1 and 13-2 are shown. As shown in Figure 1, one antenna 13 is connected to one variable-gain power amplifier 12. The antennas 13 are positioned in the microwave heating furnace 2 so as to irradiate the object to be heated, which is placed in the internal space of the microwave heating furnace 2. Each antenna 13 irradiates the object to be heated with a power-amplified chirp signal supplied from the corresponding variable-gain power amplifier 12. In the example in Figure 1, antenna 13-1 irradiates the object to be heated with a power-amplified chirp signal supplied from the variable-gain power amplifier 12-1, and antenna 13-2 irradiates the object to be heated with a power-amplified chirp signal supplied from the variable-gain power amplifier 12-2.

[0035] (Microwave heating furnace) The microwave heating furnace 2 is equipped with an inner wall made of a metal material such as aluminum and an opening / closing door that can be opened and closed to allow the object to be heated to be put in and taken out of the microwave heating furnace 2, and is configured to contain the chirp signal irradiated from the antenna 13 inside.

[0036] Next, an example of the hardware configuration of the control unit 111 will be described with reference to Figures 2A and 2B. The control unit 111 is implemented by a processing circuit. The processing circuit may be a dedicated processing circuit 111a as shown in Figure 2A, or a processor 111b that executes a program stored in memory 111c as shown in Figure 2B.

[0037] If the processing circuitry is a dedicated processing circuit 111a, then the dedicated processing circuit 111a may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (application-specific integrated circuit), an FPGA (field-programmable gate array), or a combination thereof.

[0038] When the processing circuitry is the processor 111b, the control unit 111 is implemented by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory 111c. The processor 111b implements the functions of the control unit 111 by reading and executing the programs stored in memory 111c. Here, examples of memory 111c include non-volatile or volatile semiconductor memories such as RAM (random access memory), ROM (read-only memory), flash memory, EPROM (erasable programmable read-only memory), and EEPROM (electrically erasable programmable read-only memory), as well as magnetic disks, flexible disks, optical disks, compact disks, minidiscs, and DVDs.

[0039] <Operation> The operation of the microwave heating device will be explained below. First, the object to be heated is placed inside the microwave heating furnace 2.

[0040] Next, the control unit 111 sets a control signal S1 to set the chirp parameters of multiple types of microwave band chirp signals, including a first chirp signal and a second chirp signal, whose chirp slopes are different from each other. The control unit 111 also sets the power amplification factor of the generated chirp signal as a gain control signal S2. The value of the gain control signal S2 may be a common value for the multiple variable gain power amplifiers 12, or it may be different for each of them.

[0041] Next, the chirp signal generator 112 generates two or more microwave band chirp signals according to the chirp parameters set by the control unit 111.

[0042] Next, the multiple variable-gain power amplifiers 12 adjust the power of the chirp signal output from the chirp signal generator 112 according to the gain control signal S2 output from the control unit 111, and output a power-amplified chirp signal.

[0043] Next, antenna 13 irradiates the object to be heated with a power-amplified chirp signal supplied from the corresponding variable-gain power amplifier 12. In the example in Figure 1, antenna 13-1 irradiates the object to be heated with a power-amplified chirp signal supplied from variable-gain power amplifier 12-1, and antenna 13-2 irradiates the object to be heated with a power-amplified chirp signal supplied from variable-gain power amplifier 12-2.

[0044] As a result, the object to be heated, placed inside the microwave heating furnace 2, is heated.

[0045] Furthermore, it is possible to combine embodiments, or to modify or omit each embodiment as appropriate. [Industrial applicability]

[0046] The chirp signal generating apparatus of this disclosure can be used as an apparatus for generating microwave band chirp signals for heating an object to be heated by microwaves. [Explanation of Symbols]

[0047] 1 Chirp signal radiator, 2 Microwave heating furnace, 11 Chirp signal generator, 12 (12-1, 12-2) Variable gain power amplifier, 13 (13-1, 13-2) Antenna, 111 Control unit, 111a Processing circuit, 111b Processor, 111c Memory, 112 Chirp signal generator, 1121 Reference signal generator.

Claims

1. A control unit that sets chirp parameters for multiple types of microwave band chirp signals, including a first chirp signal and a second chirp signal, each having a different chirp slope, A chirp signal generator that generates multiple types of microwave band chirp signals according to the set chirp parameters and can output the generated chirp signals to different transmission lines, A chirp signal generator equipped with, Connected to the chirp signal generator, the number of amplifiers is equal to the number of types of chirp signals generated, and each amplifier is a variable-gain power amplifier that variably power-amplifies the input chirp signal. An antenna connected to each amplifier, which radiates the amplified chirp signal, A microwave heating device equipped with the following features.

2. The lower limit frequency of the first chirp signal and the lower limit frequency of the second chirp signal are different, or the upper limit frequency of the first chirp signal and the upper limit frequency of the second chirp signal are different. A microwave heating apparatus as described in claim 1.

3. The first chirp signal is an up-chirp signal whose frequency increases over time. The second chirp signal is a down chirp signal whose frequency decreases over time. A microwave heating apparatus as described in claim 1.

4. The absolute values ​​of the chirp slopes of the multiple types of microwave band chirp signals are different from each other. A microwave heating apparatus according to any one of claims 1 to 3.

5. The antenna is arranged in a microwave heating furnace, A microwave heating apparatus according to claim 4, further comprising:

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