JP2011129341A - Microwave processing device source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave processing device source in which a plurality of power feed parts are installed, and based at least on reflected power information from each of the power feed parts, the operating frequency for supplying the generated power of a microwave generation means to a heating chamber at a high efficiency is selected. <P>SOLUTION: The microwave treatment device source is provided with a microwave generation means 10 structured by using a semiconductor element; a plurality of power feeding parts 20a-20d for supplying microwaves inside a heating chamber 100 housing a heating object; power detecting parts 18a-18d, arranged between the microwave generation means and the power feed parts, and a control means 21 for controlling the microwave generation means, based on a signal from the power detecting parts. The control means makes the microwave generation means operate over a specified frequency band and allocates the average value of a supply amount and a reflected amount, at three continuous frequencies including the object frequency, based on the supply amount and the reflected amount with respect to each of the frequencies detected by the power detecting parts; and thereby, a frequency showing a minimum value can be extracted at a high precision, as well, as stably and a high-efficient operation is realized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a microwave processing apparatus that heats an object to be heated using a microwave generating means having a frequency variable function.

  Conventional microwave processing apparatuses generally use a vacuum tube called a magnetron as microwave generation means, as represented by a microwave oven.

  The magnetron used in a microwave oven has an oscillation frequency determined by its structure, and the determined frequency cannot be varied intentionally. Although there is a technology for attaching a frequency variable function to a magnetron, it is expensive and difficult to install in a product for the general public.

  Recent advances in semiconductor technology have made it possible to put microwave generation means that are comparable to or surpassing the performance of magnetrons. The microwave generating means using a semiconductor element can easily output a microwave corresponding to a broadband frequency.

  In addition, since the properties of the object to be heated change with the microwave treatment, the microwave supplied to the heating chamber in which the object to be heated is stored changes in the degree of absorption into the object to be heated, and the microwave from the heating chamber changes. The phenomenon that the microwave is reflected on the generation means side is exhibited. Since this reflected power is consumed in the semiconductor element, control of the reflected power is an important issue in the sense of suppressing thermal destruction of the semiconductor element.

  As a means for controlling the microwave generation means using this reflected power, a means for detecting the incident / reflection direction component is provided in the waveguide connecting the magnetron and the heating chamber, and the detection signal is subjected to a predetermined change. Some control the drive of a magnetron (for example, Patent Document 1).

  Also, a sensor for measuring the incident power and reflected power supplied to the heating chamber and a means for detecting the microwave level in the heating chamber are provided, and the heat generation capacity of the object to be heated is determined based on these detection signals, and the microwave generating means is generated. There exists what controls electric power (for example, patent documents 2).

JP 04-245190 A Japanese Patent Laid-Open No. 55-039632

  However, the microwave generating means using semiconductor elements needs to operate a plurality of semiconductor elements in parallel in order to supply a large power such as a magnetron. In order to efficiently supply the output by the parallel operation to the object to be heated, the method of spatially synthesizing the electric power of the parallel operation in the heating room space that stores the object to be heated is the method that can reduce the loss most.

According to this method, a plurality of antennas are attached, and a microwave is supplied from each antenna to the heating chamber, and the microwaves that are not consumed in the heating chamber are reflected to the microwave generating means via each antenna. In order to reduce the reflected power most, it is necessary to select the operating frequency of the microwave generating means with high accuracy. The prior art has not been specifically disclosed in this regard.

  The present invention provides a plurality of power supply units, and selects an operating frequency of the microwave generation unit that can supply the generated power of the microwave generation unit to the heating chamber with high efficiency based on at least the reflected power information from each of the power supply units. An object of the present invention is to provide a microwave processing apparatus.

  In order to solve the above-described conventional problems, a microwave processing apparatus according to the present invention includes a microwave generating unit having a frequency variable function, a heating chamber for storing an object to be heated, and a microwave generated by the microwave generating unit. A plurality of power supply units that supply the heating chamber, a microwave supply amount that is provided between the power supply unit and the microwave generation unit, and is supplied to the heating chamber, and a microwave reflection that is reflected from the heating chamber to the microwave generation unit side A power detection unit that detects at least a microwave reflection amount of the signal and a control unit that controls the operation of the microwave generation unit based on a signal detected by each of the power detection units. In determining the operating frequency of the means, each power detection unit obtained for each frequency by operating the microwave generating means over a specified frequency band The microwave supply amount and the microwave reflection amount are detected, and the microwave supply amount and the microwave reflection at at least three consecutive frequencies including the frequency are detected as values of the microwave supply amount and the microwave reflection amount for each frequency. Assign an average amount.

  According to the present invention, the value of the microwave supply amount and the microwave reflection amount at each frequency can be captured as a stable value between adjacent frequencies. And based on the characteristic of the average value of each frequency, the selection calculation of the frequency which exhibits the minimum value or the minimum value can be performed stably and with high accuracy.

  According to the microwave processing apparatus of the present invention, a plurality of power supply units are provided, and a microwave that can supply the generated power of the microwave generating means to the heating chamber with high efficiency based on at least the reflected power information from each power supply unit. The operating frequency of the generating means can be selected.

FIG. 2 is a partially cutaway actual configuration diagram of the microwave processing apparatus according to Embodiment 1 of the present invention. Block diagram of the microwave processing apparatus of FIG. Arrangement configuration diagram of the power feeding section of the microwave processing apparatus of FIG. The figure which shows the frequency characteristic example of the ratio of the amount of microwave reflections with respect to the amount of microwave supply at the time of no load of the microwave processing apparatus of FIG. The figure which shows the frequency characteristic example of the amount of microwave reflections at the time of no load of the microwave processing apparatus of FIG. FIG. 1 is a control flowchart relating to the initial setting of the microwave processing apparatus of FIG. The figure which shows the frequency characteristic example of the ratio of the amount of microwave reflections with respect to the amount of microwave supply at the time of the load of the microwave processing apparatus of FIG. The figure which shows the frequency characteristic example of the amount of microwave reflections at the time of the load of the microwave processing apparatus of FIG. Control flow chart of microwave processing apparatus of FIG. Control flow chart of microwave processing apparatus of FIG.

According to a first aspect of the present invention, there is provided a microwave generation means having a frequency variable function, a heating chamber for storing an object to be heated, a plurality of power supply sections for supplying the microwave generated by the microwave generation means to the heating chamber, and a power supply section Detection that detects at least the microwave reflection amount between the microwave supply amount that is provided between each of the two and the microwave generation means and is supplied to the heating chamber and the microwave reflection amount that is reflected from the heating chamber to the microwave generation means side And a control means for controlling the operation of the microwave generation means based on the signals detected by the respective power detection parts, and the control means has a prescribed frequency band for determining the operating frequency of the microwave generation means. The microwave generation means is operated over a period of time to detect the microwave supply amount and the microwave reflection amount of each power detection unit obtained for each frequency. As the value of the microwave feed rate and the microwave reflection amount for each frequency, in which assigning the average value of the microwave feed rate and the microwave reflection amount in at least three frequency continuous including this frequency.

  Thereby, the value of the microwave supply amount and the microwave reflection amount at each frequency can be captured as a stable value between adjacent frequencies. And based on the characteristic of the average value of each frequency, the selection calculation of the frequency which exhibits the minimum value or the minimum value can be performed stably and with high accuracy.

  In the second invention, particularly in the first invention, the control means uses the detected values for the microwave supply amount and the microwave reflection amount at the frequency variable start frequency and the next frequency.

  As a result, the variable starting frequency and the processing of the next frequency, which are difficult to process the average value, are clearly defined, so that the calculation processing result based on the characteristics of the average value of the individual frequencies is not suitable, for example, the variable starting frequency and the next When the frequency of the microwave reflection amount becomes the minimum value, it can be processed that no problem occurs even if these frequencies are selected as the minimum frequency.

  In a third aspect of the invention, in particular, in the first aspect of the invention, the control means changes the frequency value and the frequency increment value changed over a specified frequency band to integer values. Thereby, the total number of variable frequencies can be reduced and the detection processing time can be shortened. Therefore, the process of determining the operating frequency can be freely given at any timing within the heating operation period.

  According to a fourth aspect of the invention, in the first aspect of the invention, the control means operates the microwave generation means over a specified frequency band in a state where the object to be heated is not accommodated in the heating chamber, and for each frequency. The ratio of the sum of the microwave reflection amounts of the respective power detection units obtained or the ratio of the sum of the microwave reflection amounts to the sum of the microwave supply amounts of the respective power detection units obtained with respect to individual frequencies corresponds to the frequency change. Thus, the frequency value exhibiting the minimum value is stored as a group of reference frequencies. Thereby, the accuracy of the presence / absence determination of the object to be heated in the heating chamber can be increased.

  According to a fifth aspect of the present invention, in particular, in the first aspect, when the control means receives a command to start the operation of the microwave generation means, the operating frequency of the microwave generation means regardless of the presence or absence of the object to be heated. In order to select, the microwave generation means is operated over a specified frequency band to supply microwaves to the heating chamber, and the microwave reflection amount of each power detection unit obtained for each frequency The frequency at which the ratio of the sum of the microwave reflection amount signals to the sum of the microwave supply amounts of the respective power detection units obtained for each frequency is minimal is extracted, and the extracted frequency is stored. Compared with the group of reference frequencies, a frequency that is different from the group of reference frequencies and has a minimum reflection amount sum or ratio is a frequency of the microwave generating means. It is intended to initiate a decision to operate to create frequency.

  Accordingly, it is possible to provide an apparatus that eliminates power waste by reliably confirming the storage of the object to be heated in the heating chamber and operating at a highly efficient frequency.

In a sixth aspect of the invention, particularly in the fourth or fifth aspect of the invention, the control means includes, as a group of reference frequencies, a frequency increment value that changes over a specified frequency band plus or minus each of the reference frequencies. Is. As a result, the microwave supply amount and the microwave reflection amount change even when there is no object to be heated in accordance with the secular change of the state in the heating chamber, for example, the food residue attached to the wall surface of the heating chamber. The presence / absence determination of the object to be heated can be executed with high accuracy in consideration of the above.

  In the seventh invention, particularly in the fifth invention, when there are a plurality of frequencies having a minimum value, the control means determines the frequency having the lower frequency value as the operating frequency. Thereby, the comparison process can be simplified and the entire frequency determination process can be speeded up.

  In the eighth invention, particularly in the fifth invention, the control means stops the operation start of the microwave generating means when all of the extracted frequencies coincide with the stored reference frequency group. Thereby, it can suppress that the component of a microwave generation means is thermally destroyed by the reflected microwave electric power.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is an actual configuration diagram showing a part of the microwave processing apparatus according to the first embodiment of the present invention, and FIG. 2 is a block configuration of the microwave processing apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram showing the configuration of the power feeding unit of the microwave processing apparatus according to the first embodiment of the present invention.

  1 to 3, the microwave generation means 10 includes an oscillation unit 11 configured using a semiconductor element, three power distribution units 12a, 12b, 12c having a two-stage configuration that distributes the output of the oscillation unit 11 into four stages, and The outputs of the microwave transmission paths 14a to 14d and the first stage amplifying units 13a to 13d that guide the outputs of the power distribution units 12b and 12c to the first stage amplifying units 13a to 13d configured by using the semiconductor elements in the subsequent stage are further amplified. Microwave transmission paths 17a to 17d and microwave transmission paths 17a to 17d that lead the outputs of the main amplification sections 15a to 15d and the main amplification sections 15a to 15d configured using semiconductor elements to the output sections 16a to 16d of the microwave generation means 10, respectively. Phase inserted between the power detectors 18a to 18d and the output of the power distributor 12a and the inputs of the power distributors 12b and 12c Changing portions 19a, it is composed of a 19b.

  In addition, the microwave processing apparatus of the present invention includes a heating chamber 100 having a substantially rectangular parallelepiped structure that accommodates an object to be heated. The heating chamber 100 includes a left wall surface 101, a right wall surface 102, a bottom wall surface 103, and an upper surface made of a metal material. A wall surface 104, a back wall surface 105, and an opening / closing door 106 that opens and closes in order to store an object to be heated, are configured to confine the supplied microwave.

  A plurality of power feeding units 20 a to 20 d that transmit the four outputs of the microwave generation means 10 and radiate the microwaves into the heating chamber 100 are arranged on the bottom wall surface 103 constituting the heating chamber 100. The plurality of power feeding units 20a to 20d are arranged on the bottom wall surface 103 so that the substantially center C0 of the bottom wall surface 103 is point-symmetric.

  The first stage amplifying units 13a to 13d and the main amplifying units 15a to 15d constitute a circuit with a conductor pattern formed on one surface of a dielectric substrate made of a low dielectric loss material, and are semiconductor elements that are amplifying elements of the amplifying units. Matching circuits are arranged on the input side and the output side of each semiconductor element in order to operate the semiconductor device satisfactorily.

The microwave transmission paths 14a to 14d and 17a to 17d form a transmission circuit having a characteristic impedance of about 50Ω by a conductor pattern provided on one surface of a dielectric substrate. The power distribution units 12a, 12b, and 12c have a Wilkinson power 2 distribution configuration. By adopting this configuration, the phases of the microwaves transmitted to the input ends of the first stage amplification units 13a to 13d are ideally the same phase.

  The phase variable units 19a and 19b provided between the power distribution unit 12a and the power distribution units 12b and 12c have a circuit configuration in which a variable capacitance diode is incorporated as a reflection type phase circuit.

  The characteristic of this reflection type phase circuit is that the phase lag becomes 180 ° or more at maximum by changing the voltage applied to the variable capacitance diode for transmission at the center frequency of the frequency band used for the microwave processing device. Variable diode selection and applied voltage variable range are set.

  By controlling the operation of the phase variable sections 19a and 19b, the phase difference between the output sections 16a and 16b and the output sections 16c and 16d of the microwave generating means 10 can be changed by 360 ° at the maximum.

  The power detection units 18a to 18d are so-called microwave power (hereinafter referred to as a microwave supply amount) transmitted from the microwave generation means 10 to the heating chamber 100 and so-called transmission from the heating chamber 100 to the microwave generation means 10 side. The amount of reflected microwaves (hereinafter referred to as the amount of reflected microwaves) detects at least the amount of reflected microwaves, and the power coupling degree is, for example, about 40 dB, and the amount of microwaves supplied through the microwave transmission paths 17a to 17d or An electric energy of about 1/10000 of the microwave reflection amount is extracted.

  Each power signal is rectified by a detection diode (not shown), smoothed by a capacitor (not shown), and the output signal is input to the control means 21. Further, the reference frequency group values obtained when the initial setting operation of the control means 21 is executed are stored in the storage unit 21a.

  The control means 21 controls the heating condition (arrow 22) of the object to be heated directly input by the user, the detection information (arrow 23) from each of the power detection units 18a to 18d, and the heating state of the object to be heated during heating. Based on the heating information obtained from various sensors for detecting the oscillation, the oscillation frequency and oscillation output of the oscillation unit 11 which is a component of the microwave generation means 10 are controlled, and the voltage applied to the phase variable units 19a and 19b is controlled. The object to be heated housed in the heating chamber 100 is optimally heated.

  The microwave generating means 10 is provided with heat radiating means (not shown) for radiating heat generated by the semiconductor element. In addition, in the heating chamber 100, a placing plate 24 made of a low dielectric loss material that covers and feeds the object to be heated and covers the power feeding units 20a to 20d provided on the bottom wall surface 103 is disposed.

  About the microwave processing apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. Prior to the use of this apparatus, initial setting is performed in a state where no load is stored in the heating chamber.

  In this execution, it is confirmed that an object to be heated is not stored in the heating chamber 100, and an initial setting execution key is pressed from an operation unit (not shown). In response to the control output signal of the control means 21 that receives this signal, the microwave generation means 10 starts operating. The control means 21 operates a drive power supply (not shown) to supply power to the first stage amplifiers 13a to 13d and the main amplifiers 15a to 15d. Thereafter, a signal for setting the driving power and the oscillation frequency to 2400 MHz is supplied to the oscillating unit 11, and oscillation starts.

  Note that the voltages applied to the phase variable sections 19a and 19b at this stage are defined in advance. For example, both the phase variable units 19a and 19b have no phase delay, or only one of the phase variable units is set to a phase delay of about 180 degrees.

  When the oscillating unit 11 is operated, its output is distributed approximately ½ by the power distribution unit 12a, further approximately ½ distributed by the subsequent power distributors 12b and 12c, and becomes four microwave power signals. The signals are output to the output units 16a to 16d via the subsequent first stage amplification units 13a to 13d and the main amplification units 15a to 15d, respectively.

  Each output is transmitted to the power feeding units 20 a to 20 d and radiated into the heating chamber 100. At this time, when both of the phase variable units 19a and 19b have no phase delay, the phases of the microwave signals radiated from the power feeding units 20a to 20d are the same phase. Note that the phase difference between the power supply units 20a and 20b and the power supply units 20c and 20d is determined according to the voltage applied to the phase variable units 19a and 19b.

  In this initial setting, each of the main amplification units 15a to 15d outputs microwave power corresponding to 1/10 of the rated output, for example, microwave power of 20W.

  Part of the microwave power supplied into the heating chamber 100 is absorbed by the heating chamber wall surface and a dielectric member mounted in the heating chamber, and the electrical characteristics of the heating chamber 100 vary depending on the resonance state of the heating chamber. Therefore, the reflected power transmitted from the heating chamber 100 side to the microwave generating means 10 side is generated based on the output impedance of the microwave generating means 10 and the impedance of the heating chamber 100.

  The power detection units 18a to 18d are combined with at least the reflected power transmitted to the microwave generation means 10 and detect signals proportional to the amount of reflected microwaves. The control means 21 changes the frequency over the entire frequency band defined in advance with respect to the oscillating unit 11 in the initial setting step by step with an incremental frequency value that takes an integer value, and thus a reference frequency corresponding to the initial characteristics of the heating chamber. To extract.

  FIG. 4 shows a frequency characteristic example of the ratio of the microwave reflection amount to the microwave supply amount when there is no load in the microwave processing apparatus of the present invention, and FIG. 5 shows a frequency characteristic example of the microwave reflection amount when there is no load. In each figure, the white characteristics indicate the characteristics based on the microwave supply and microwave reflection values obtained directly at the individual frequencies, and the black characteristics indicate the characteristics after averaging processing. Show.

  In this averaging process, as the values of the microwave supply amount and the microwave reflection amount for each frequency, the average value of the microwave supply amount and the microwave reflection amount at three consecutive frequencies including the frequency is used as the target frequency. Assign as the value of.

  Specifically, the microwave supply amount and microwave reflection amount at 2400 MHz which is the frequency variable start frequency and 2401 MHz which is the next frequency use the detected values, and at each frequency from 2402 MHz to 2500 MHz, the target frequency A value obtained by performing an average processing of the microwave supply amount and the microwave reflection amount detected at the previous and two previous frequencies is set as the value of the target frequency.

  For example, a value of 2402 MHz is an average value of three values detected at respective frequencies of 2400 MHz, 2401 MHz, and 2402 MHz.

FIG. 6 shows an initial control flowchart. There is no storage of the object to be heated in the heating chamber 100, and an initial setting start key is pressed from the operation unit (not shown) to generate a heating start signal (step S101 in FIG. 5). In the control means 21 to which the heating start signal is input, a control output signal is generated, and the operation is started by setting the total output of the microwave generation means 10 to the first output power, for example, less than 100 W. (Step S102). At this time, the control means 21 supplies a predetermined drive power supply voltage to the first stage amplifiers 13a to 13d and the main amplifiers 15a to 15d.

  Further, the control means 21 outputs a control signal for setting the initial oscillation frequency of the oscillation unit 11 to 2400 MHz, and starts the oscillation operation of the oscillation unit 11. Thus, the microwave generation means 10 outputs the microwave power of less than 100 W at 2400 MHz as the first output power in the initial stage.

  Next, in step S103, the oscillation frequency of the oscillation unit 11 is changed from the initial 2400 MHz to a higher frequency at a 1 MHz pitch (for example, 1 MHz in 10 milliseconds), and is changed to 2500 MHz which is the upper limit of the frequency variable range. In this frequency variable operation, the values of the microwave transmission amount Pf and the microwave reflection amount Pr obtained from the power detection units 18a to 18d are stored.

  Then, the averaging process described above is executed as the values of the microwave supply amount and the microwave reflection amount for each frequency, and the process proceeds to step S104.

  In step S104, a frequency that exhibits a minimum value in the ratio of the microwave reflection amount or the frequency change characteristic of only the microwave reflection amount based on the microwave supply amount and the microwave reflection amount at the individual frequencies subjected to the averaging process (for example, The frequencies fA1, fA2, fA3, fA4 in FIG. 4 or the frequencies fB1, fB2, fB3, fB4) in FIG. 5 are extracted and the process proceeds to step S105.

  In step S105, each frequency extracted in step 104, including the frequency plus 1 MHz and the frequency minus -1 MHz, is stored in the storage unit 21a as a group of reference frequencies, and the initial setting flow ends.

  Next, an operation in performing heating of the object to be heated housed in the heating chamber will be described. The object to be heated is stored in the heating chamber 100, the heating condition is input from the operation unit (not shown), and the heating start key is pressed. In response to the control output signal of the control means 21 that has received the heating start signal, the microwave generation means 10 starts its operation. The control means 21 operates a drive power supply (not shown) to supply power to the first stage amplifiers 13a to 13d and the main amplifiers 15a to 15d.

  Thereafter, a signal for setting the driving power and the oscillation frequency to 2400 MHz is supplied to the oscillating unit 11, and oscillation starts. Note that the voltages applied to the phase variable sections 19a and 19b at this stage are defined in advance. For example, both the phase variable units 19a and 19b have no phase delay, or only one of the phase variable units is set to a phase delay of about 180 degrees.

  When the oscillating unit 11 is operated, its output is distributed approximately ½ by the power distribution unit 12a, further approximately ½ distributed by the subsequent power distributors 12b and 12c, and becomes four microwave power signals. The signals are output to the output units 16a to 16d via the subsequent first stage amplification units 13a to 13d and the main amplification units 15a to 15d, respectively.

  Each output is transmitted to the power feeding units 20 a to 20 d and radiated into the heating chamber 100. At this time, when both of the phase variable units 19a and 19b have no phase delay, the phases of the microwave signals radiated from the power feeding units 20a to 20d are the same phase.

  Note that the phase difference between the power supply units 20a and 20b and the power supply units 20c and 20d is determined according to the voltage applied to the phase variable units 19a and 19b.

  In the stage before starting the heating of the object to be heated, each of the main amplifying units 15a to 15d outputs microwave power corresponding to 1/10 of the rated output, for example, microwave power of 20W.

  When 100% of the microwave power supplied into the heating chamber 100 is absorbed by the object to be heated, there is no reflected power from the heating chamber 100, but the type / shape / quantity of the object to be heated includes the object to be heated. Based on the output impedance of the microwave generation means 10 and the impedance of the heating chamber 100, the reflected power transmitted from the heating chamber 100 side to the microwave generation means 10 side is generated.

  The power detection units 18a to 18d are combined with at least the reflected power transmitted to the microwave generation means 10 and detect signals proportional to the amount of reflected microwaves. The control means 21 selects a frequency to be used during the main heating of the object to be heated by stepping the frequency over the entire frequency band defined in advance with respect to the oscillation unit 11 before starting the heating of the object to be heated.

  In response to this frequency selection, the control means 21 changes the oscillation frequency of the oscillating unit from the initial 2400 MHz to 2500 MHz which is the upper limit of the frequency variable range at a 1 MHz pitch (for example, 1 MHz in 10 milliseconds). Based on the microwave supply value and the microwave reflection value at each frequency after performing the averaging process of the microwave supply amount and the microwave reflection amount obtained in this frequency variable, A frequency at which the ratio of the microwave reflection amount value is minimized is extracted.

  Then, the extracted frequency group is collated with a reference frequency group stored in advance, and when there is a frequency that does not match, it is determined that the object to be heated is stored, and the frequency having the smallest ratio among the extracted frequencies is determined. It is determined as the operating frequency of the microwave generating means.

  Then, the frequency of the oscillating unit 11 is controlled to the determined frequency, and the oscillation output is controlled so as to obtain an output corresponding to the input heating condition. In response to this output, during main heating of the object to be heated, each of the main amplifying units 15a to 15d outputs microwave power of around 200W. Each output is transmitted to the power feeding units 20 a to 20 d and radiated into the heating chamber 100.

  The plurality of power feeding units 20a to 20d are arranged so that the substantially center C0 of the bottom wall surface 103 is point-symmetric. When the object to be heated is accommodated and placed on the mounting plate 24 substantially above the center C0, the power feeding units 20a to 20d receive the microwaves supplied into the heating chamber 100, and the power detection units 18a to 18d. The amount of reflected microwaves detected by is substantially equal.

  When the microwave reflection amounts detected by the power detection units 18a to 18d at the start of the main heating are greatly different, the control means 21 is configured to place the object to be heated on the upper side of the bottom wall surface 103 substantially at the center C0. 24, it can be determined that the storage arrangement is considerably deviated from above, and the user may be informed to redo the storage arrangement.

  Then, in the time variation change characteristic of the microwave reflection amount detected by each of the power detection units 18a to 18d during the main heating of the object to be heated, the time variation change of the microwave reflection amount of at least one power detection unit is changed. The heating distribution state of the object to be heated is estimated based on the above, and the temperature rise state of the object to be heated is estimated based on the temporal change in the amount of microwave reflection of all the power detection units, and the oscillation frequency of the microwave generating means Update and stop operation are controlled.

  Next, the operation of the microwave processing apparatus according to the first embodiment of the present invention configured as described above will be described with reference to FIGS.

  FIG. 7 shows an example of the ratio of the sum of the microwave reflection amounts to the sum of the microwave supply amounts at the individual frequencies calculated based on the detection signals of the power detection units 18a to 18d in the microwave processing apparatus of the first embodiment. FIG. 8 is a characteristic diagram showing an example of the total sum of microwave reflection amounts in the same apparatus.

  In each figure, the white characteristics indicate the characteristics based on the microwave supply and microwave reflection values obtained directly at the individual frequencies, and the black characteristics indicate the characteristics after averaging processing. Show.

  The frequencies extracted as frequencies exhibiting the minimum are f11, f12, f13, and f14 in FIG. 7, and f21, f22, f23, and f24 in FIG.

  In each figure, reference frequencies fA1, fA2, fA3 and fA4, and fB1, fB2, fB3 and fB4 (note that the frequency of plus or minus 1 MHz with respect to the reference frequency is omitted) are added.

  The extracted frequency in FIGS. 7 and 8 is compared with the reference frequency, and since there is a frequency different from the reference frequency in the extracted frequency group, it is determined that there is an object to be heated.

  Further, the frequency at which the ratio takes the minimum value in FIG. 7 is f14, and the frequency at which the reflection amount takes the minimum value in FIG. 8 is f24. The control means 21 uses the frequency f14 when using the control process using the ratio of the sum of the microwave reflection amounts to the sum of the microwave supply amounts, and the control means 21 uses the control process using the sum of the microwave reflection amounts. Selects the frequency f24 as the frequency in the main heating operation of the object to be heated.

  When the extracted frequency groups are compared with each other, f23 corresponding to f13 results in a frequency shift of 6 MHz. As the selection of the parameters of the detection signal, the simple configuration is positioned based on the microwave reflection amount, and the high-accuracy configuration is positioned based on the ratio.

  Below, the detailed control example of the microwave processing apparatus of Embodiment 1 which concerns on this invention is demonstrated using the flowchart of FIG. 9 and FIG.

  The object to be heated is accommodated in the heating chamber 100 and placed on the mounting tray 24, and the heating condition is set in the operation unit (not shown) (even if the object to be heated is not accommodated), and the heating start key Is pressed to generate a heating start signal (step S111 in FIG. 9). In the control means 21 to which the heating start signal is input, a control output signal is generated, and the operation is started by setting the microwave generation means 10 to the first output power, for example, a power of less than 100 W (step S112). ).

  At this time, the control means 21 supplies a predetermined drive power supply voltage to the first stage amplifiers 13a to 13d and the main amplifiers 15a to 15d. Further, the control means 21 outputs a control signal for setting the initial oscillation frequency of the oscillation unit 11 to 2400 MHz, and starts the oscillation operation of the oscillation unit 11. Thus, the microwave generation means 10 outputs the microwave power of less than 100 W at 2400 MHz as the first output power in the initial stage.

  Next, in step S113, the oscillation frequency of the oscillating unit 11 is changed from the initial 2400 MHz to a higher frequency at a 1 MHz pitch (for example, 1 MHz in 10 milliseconds), and is changed to 2500 MHz which is the upper limit of the frequency variable range. In this frequency variable operation, the microwave transmission amount and the microwave reflection amount obtained from the power detection units 18a to 18d are taken in and the above-described averaging process is performed, and the process proceeds to step S114.

  In step S114, based on the microwave supply amount and the microwave reflection amount of each frequency subjected to the averaging process, a frequency (for example, in FIG. 7) showing a minimum value in the frequency characteristic of the ratio of the microwave reflection amount to the microwave supply amount. The frequencies f11, f12, f13, and f14) are extracted and the process proceeds to step S115.

  In step S115, the group of frequencies extracted in step S114 is collated with a group of reference frequencies stored in advance, and the process proceeds to step S116.

  In step S116, it is determined whether there is a frequency that does not match the extracted frequency group with respect to the reference frequency group. If there is an extracted frequency that does not match, the process proceeds to step S117. When there is no extraction frequency that does not match, the process proceeds to step S118, where it is determined that there is no object to be heated, and the operation of the microwave generation unit is stopped and the heating operation is stopped.

  In step S117, the frequency having the smallest ratio in the extracted frequency group, f14 in FIG. 7, is selected, and the process proceeds to step S119.

  In step S119, the output power of the oscillating unit 11 is controlled so that the microwave generation means 10 generates the second output power that is the rated output. In setting the second output power, the control unit 21 may control the drive voltages of both the first stage amplification units 13a to 13d and the main amplification units 15a to 15d in accordance with the specifications of the microwave processing device. The configuration may be such that only the drive voltage of the main amplifiers 15a to 15d is controlled.

  Next, the full-scale heating operation is started with the second output power set in step S120. When the full-scale heating operation is started, the process proceeds to step S121, the integration of the full-scale heating time is started, and the process proceeds to step S122. In step S122, the control means 21 captures a detection signal corresponding to the microwave transmission amount and the microwave reflection amount detected by each power detection unit at that time, and the process proceeds to step S123.

  In step S123, any one of the microwave reflection amounts detected by the power detection units 18a to 18d is a specified value (a value corresponding to a ratio of the microwave reflection amount to the microwave transmission amount in each power detection unit is 25%). Determine if it is: If the microwave reflection amount of each power detection unit does not exceed the specified value, the process proceeds to step S124, and if it exceeds, the process proceeds to step S201.

  In step S <b> 124, the heating progress state of the object to be heated is determined by comparing temporal changes in the amount of microwave reflection detected by the respective power detection units. This determination is made based on the temporal increase / decrease change in the amount of microwave reflection of the four individual power detection units.

  In the case of the same tendency based on the judgment result of whether the change in time of four individual microwave reflection amounts is not reverse trend (almost the same trend) or one of them is in the reverse trend increase / decrease The process proceeds to step S125, and if the tendency is reverse, the process proceeds to step S112.

After returning to step S112 and updating the frequency used at the time of full-scale heating in a series of steps up to step S115, the process proceeds to step S120 via steps S116, S117, and S119, and full-scale heating is resumed.

  If the same tendency is determined in step S124, the process proceeds to step S125. If it is determined in step S125 that the change in the microwave reflection amount per unit time is significant, the process proceeds to step S126.

  In step S126, various condition processing until the heating of the object to be heated is completed. For example, the control means 21 determines that the temperature of the object to be heated has reached approximately 60 ° C to 70 ° C.

  Then, based on the elapsed heating time up to the present time and the actual value of the input microwave power, the time to reach the finishing temperature of the object to be heated is calculated and heating is continued.

  In addition, if any one of the respective microwave reflection amounts detected by the power detection unit during the time until the finish temperature is reached exceeds the above-mentioned specified value (50 W), a condition for terminating the heating at that time is also incidental. I am letting. And it progresses to step S127 and complete | finishes heating by satisfy | filling one of the heating completion conditions mentioned above.

  Next, the control contents after step S201 when the microwave reflection amount exceeds the specified value in step S123 will be described.

  In step S201, the control unit 21 outputs a control signal for setting the initial oscillation frequency of the oscillating unit 11 to 2400 MHz and the microwave power of the microwave generation unit 10 to the first output power, and the process proceeds to step S202.

  In step S202, the oscillation frequency of the oscillating unit 11 is changed from the initial 2400 MHz to a higher frequency at a 1 MHz pitch (for example, 1 MHz in 10 milliseconds), and is changed to 2500 MHz which is the upper limit of the frequency variable range. In this frequency variable operation, the microwave transmission amount and the microwave reflection amount obtained from the power detection units 18a to 18d are stored, respectively, and the process proceeds to step S203.

  In step S203, a new frequency group showing a minimum value in the frequency characteristic curve of the microwave reflection amount obtained from the power detection units 18a to 18d is extracted, and the process proceeds to step S204. In step S204, the frequency with the smallest amount of microwave reflection is selected, the heating frequency is updated, and the process proceeds to step S205.

  In step S205, the output power of the oscillating unit 11 is controlled so that the microwave generation means 10 generates the second output power that is the rated output, and the process proceeds to step S206.

  In step S206, the full-scale heating operation is started with the second output power with the updated heating frequency, and the process proceeds to step S207.

  In step S207, the amount of microwave reflection detected by each of the power detection units 18a to 18d is equal to or less than a specified value, for example, a value corresponding to a ratio of the microwave reflection amount to the microwave transmission amount transmitted to each power feeding unit (25%). When the microwave transmission amount is 200 W, it is determined whether the specified value is 50 W or less. When the microwave reflection amount does not exceed the specified value, the process returns to step S119, and when it exceeds the specified value, the process proceeds to step S208.

In step S208, the output of the oscillator 11 is reduced. In this reduction method, for example, when the second output power is 100%, the output of the oscillation unit 11 is reduced so as to generate output power corresponding to 90%, 75%, and 50%. The output of the oscillating unit 11 is reduced until all of the microwave reflection amounts detected by the respective power detection units are equal to or less than the specified value.

  For the second output power setting, the control means 21 may control the drive voltages of the first stage amplifiers 13a to 13d and the main amplifiers 15a to 15d, or only the drive voltages of the main amplifiers 15a to 15d. It is good also as a structure which controls.

  This method may also be developed when the output power is reduced from the second output power in step S208. That is, the drive voltage of the first stage amplification units 13a to 13d and / or the main amplification units 15a to 15d is reduced and the output power of the microwave generation means 10 is reduced, and the process returns to step S207, and the microwaves detected by each power detection unit Control for returning to step S119 may be employed when the drive voltage reduction adjustment is executed until all the reflection amounts are equal to or less than the specified value.

  In steps S114 and S115, processing using only the microwave reflection amount may be performed instead of the ratio of the microwave reflection amount based on both the microwave transmission amount and the microwave reflection amount.

  As described above, according to the microwave processing apparatus of the present invention, when determining the operating frequency of the microwave generating means, the control means operates the microwave generating means over a specified frequency band, and sets individual frequencies. The microwave supply amount and the microwave reflection amount of each power detection unit obtained for each are detected, and the value of the microwave supply amount and the microwave reflection amount for each frequency is at least three consecutive including the frequency. By assigning the average value of the microwave supply amount and the microwave reflection amount at each frequency, the value of the microwave supply amount and the microwave reflection amount at each frequency can be captured as a stable value between adjacent frequencies. it can. And based on the characteristic of the average value of each frequency, the selection calculation of the frequency which exhibits the minimum value or the minimum value can be performed stably and with high accuracy.

  The control means clearly defines the variable start frequency and the next frequency processing, which are difficult to average by using the detected values for the microwave supply amount and the microwave reflection amount at the frequency variable start frequency and the next frequency. Inappropriate calculation processing results based on the characteristics of the average value of individual frequencies, such as the variable start frequency and the next frequency, when the amount of microwave reflection is the minimum value, Even if these frequencies are selected, it is possible to process that no problem occurs.

  In addition, the control means can reduce the total number of variable frequencies and shorten the detection processing time by setting the frequency value and frequency increment value to be changed over a specified frequency band to integer values. Therefore, the process of determining the operating frequency can be freely given at any timing within the heating operation period.

  Further, the control means operates the microwave generation means over a specified frequency band in a state where the object to be heated is not accommodated in the heating chamber, and the microwave reflection amount of each power detection unit obtained for each frequency. Or the ratio of the sum of the microwave reflection amounts to the sum of the microwave supply amounts of the respective power detection units obtained for each frequency is a frequency value that exhibits a minimum value with respect to the frequency change. By storing as a group, the accuracy of the presence / absence determination of the object to be heated in the heating chamber can be increased.

When the control means receives a command to start the operation of the microwave generation means, the control means selects a frequency of operation of the microwave generation means regardless of the presence or absence of the object to be heated over a specified frequency band. The microwave generation means is operated to supply microwaves to the heating chamber, and the total microwave reflection amount of each power detection unit obtained for each frequency, or obtained for each frequency. The frequency at which the ratio of the sum of the microwave reflection amount signals to the sum of the microwave supply amounts of the respective power detection units is minimal is extracted, and the extracted frequency is compared with the reference frequency group stored, and the reference frequency group The frequency at which the sum of reflection amounts or the ratio exhibits a minimum value is determined as the operating frequency of the microwave generating means and the operation is started. And ensures that the check the housing of the object to be heated to the heating chamber, by operating at a high efficiency frequency, can provide a device to eliminate power dissipation.

  In addition, the control means includes, as a group of reference frequencies, a frequency change value that is changed over a specified frequency band, and includes a frequency that is plus or minus to each of the reference frequencies, so that the state of the heating chamber changes over time, for example, the heating chamber. The amount of microwave supply and the amount of microwave reflection change even when there is no object to be heated due to the food residue adhering to the wall surface. Can be executed.

  In addition, when all of the extracted frequencies coincide with the stored reference frequency group, the control means causes the components of the microwave generation means to be thermally destroyed by the reflected microwave power by stopping the operation start of the microwave generation means. Can be suppressed.

  Note that when there are a plurality of frequencies having a minimum value, the control means determines the frequency with the lower frequency value as the operating frequency. This simplifies the comparison process and speeds up the entire frequency determination process.

  In this embodiment, the number of power feeding units is four. However, the number of power feeding units is not limited to this number, and may be a case where a phase difference control function between power feeding units is exhibited. For example, it can be used in any number of two or more.

  In addition, for three consecutive frequencies, the target frequency may be set as the central frequency.

  As described above, the microwave processing apparatus according to the present invention is provided with a plurality of power feeding units, and based on at least the reflected power information from each power feeding unit, the generated power of the microwave generating means is efficiently transferred to the heating chamber. Since the operating frequency of the microwave generating means that can be supplied can be selected, the present invention can be applied to applications such as a heating apparatus, a garbage disposal machine, a semiconductor manufacturing apparatus, or a drying apparatus that uses dielectric heating as represented by a microwave oven.

10 Microwave generator 11 Oscillator (having frequency variable function)
18a to 18d Power detection unit 20a to 20d Power supply unit 21 Control unit 21a Storage unit 100 Heating chamber 12 Switching control unit 13 Drive circuit unit 14 Current detection unit 14a Resistor 14b Zener diode 14c Photocoupler (light emitting side)

Claims (8)

Microwave generation means having a variable frequency function, a heating chamber that houses an object to be heated, a plurality of power supply units that supply the microwave generated by the microwave generation means to the heating chamber, the power supply unit, and the microwave A power detection unit that detects at least a microwave reflection amount between a microwave supply amount that is provided between the generation unit and supplied to the heating chamber and a microwave reflection amount that is reflected from the heating chamber toward the microwave generation unit. And control means for controlling the operation of the microwave generation means based on the signals detected by the respective power detection units, and the control means is defined when determining the operating frequency of the microwave generation means. The microwave generation means is operated over the frequency band of the respective power detection units, and the microwave supply amount and the macro obtained for each frequency are obtained. The amount of microwave reflection is detected, and the value of the microwave supply amount and the microwave reflection amount for each frequency is calculated as the average value of the microwave supply amount and the microwave reflection amount at at least three consecutive frequencies including that frequency. Microwave processing device to be assigned. The microwave processing apparatus according to claim 1, wherein the control means uses detected values for the microwave supply amount and the microwave reflection amount at the frequency variable start frequency and the next frequency. The microwave processing apparatus according to claim 1, wherein the control means sets the frequency value and frequency increment value to be changed over a specified frequency band as integer values. The control means operates the microwave generation means over a specified frequency band in a state where the object to be heated is not housed in the heating chamber, and the microwave reflection amount of each power detection unit obtained for each frequency is controlled. The reference frequency group is a frequency value at which the ratio of the sum of the microwave reflection amounts to the sum of the microwave supply amounts of the respective power detection units obtained for each frequency is a minimum value with respect to the frequency change. The microwave processing apparatus according to claim 1, which is stored as When the control means receives a command to start the operation of the microwave generation means, it selects the operation frequency of the microwave generation means regardless of the presence or absence of the object to be heated over a specified frequency band. The microwave generation means is operated to supply microwaves to the heating chamber, and the total amount of microwave reflection of each power detection unit obtained for each frequency, or each obtained for each frequency The frequency at which the ratio of the sum of the microwave reflection amount signals to the sum of the microwave supply amounts of the power detection section of the power detection unit is minimal is extracted, and the extracted frequency is compared with the reference frequency group stored, and the reference frequency group Determines the operating frequency of the microwave generating means as the operating frequency of the microwave generating means, and starts the operation when there are different frequencies and the total reflection amount or the ratio is the minimum value. Microwave apparatus according to claim 1 which is. The microwave processing apparatus according to claim 4 or 5, wherein the control means includes, as the group of reference frequencies, a frequency increment value that is changed over a specified frequency band plus or minus each of the reference frequencies. . 6. The microwave processing apparatus according to claim 5, wherein the control means determines the frequency having the lower frequency value as the operating frequency when there are a plurality of frequencies having a minimum value. 6. The microwave processing apparatus according to claim 5, wherein the control means stops the operation start of the microwave generation means when all of the extracted frequencies coincide with the stored reference frequency group.

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