JP2014049276A - Microwave processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave processing device capable of achieving uniform heating without adding nor processing a mechanism component at all.SOLUTION: A microwave processing device comprises an oscillation part 12, a power distribution part 13, a first phase controller 14a and a second phase controller 14b, a first power amplification part 15a and a second power amplification part 15b, a first power feeding part 17a and a second power feeding part 17b, a first power detector 18a and a second power detector 18b, and a controller 19 controlling a microwave generation device 11. The microwave processing device is configured so that a phase of the phase controllers is changed at a cycle inversely proportional to an incident power supplied to the power feeding parts in a heating operation, and is controlled for each predetermined combination by which a phase difference in each microwave output of the power distribution part becomes an integral multiple of 90 degrees for each cycle.

Description

  The present invention relates to a microwave processing apparatus.

  Conventionally, various proposals have been made for this type of microwave processing apparatus regarding uniform heating of an object to be heated. Regarding a plurality of microwave power supplies, a high-frequency processing apparatus has been proposed that continuously changes the mode of microwaves generated by a magnetron by alternately closing two power supply ports with sliding means such as solenoids. (For example, refer to Patent Document 1).

  Further, there has been proposed a high-frequency processing apparatus characterized in that an uneven portion for reducing the contact area between the object to be heated and the bottom surface is provided on the cavity wall surface (see, for example, Patent Document 2).

JP 59-029397 JP 2003-307317 A

  The conventional high-frequency processing apparatus agitates the microwave incident on the heating chamber by adding mechanical components such as a stirrer fan, a rotating table, and a rotating antenna.

  Further, Patent Document 1 has a configuration in which power is supplied at a plurality of locations by a sliding means such as a solenoid.

  On the other hand, in Patent Document 2, microwaves are concentrated and diffused by a configuration in which the cavity wall surface shape is uneven.

  However, the conventional configuration requires the addition of rotating mechanism parts, the addition of power feeding points, and the processing of the cavity wall surface, which has the adverse effect of reducing the volume of the heating chamber, and the cost tends to increase. It had the subject that it resulted in the contrary to the request | requirement of size reduction and cost reduction.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a microwave processing apparatus that realizes uniform heating without adding and processing any mechanical parts.

In order to solve the above-described conventional problems, a microwave processing apparatus of the present invention includes a heating chamber that houses an object to be heated, an oscillation unit that generates microwave power, and power that distributes the output of the oscillation unit to a plurality of units. A distribution unit, first and second phase control units that control the phase of the microwave output from the power distribution unit, and a semiconductor element that amplifies the output of the first and second phase control units are used. First and second power amplifying units, first and second power feeding units for supplying outputs of the first and second power amplifying units to the heating chamber, and the first and second power amplifying units. First and second for detecting incident power supplied to the first and second power feeding units from the unit and power reflected from the first and second power feeding units to the first and second power amplification units Power control unit, a control unit for controlling the oscillation unit and the first and second phase control unit, Control unit, as a control of the microwave supplied to the first and second feeding portion, an output of the first and second power amplifier before the heating operation is started is low power operation,
A condition in which the reflected power detected by the first and second power detection units is minimized by changing the oscillation frequency of the oscillation unit within a predetermined frequency range, and the first and second conditions are searched under the searched condition. The output of the power amplifying unit is shifted to a heating operation by performing a predetermined output operation, and the phases of the first and second phase control units are supplied to the first and second power feeding units during the heating operation. Variable in a cycle inversely proportional to the incident power, and configured to be controlled for each predetermined combination in which the phase difference in each microwave output of the power distribution unit is an integer multiple of 90 degrees for each variable cycle. is there.

  Accordingly, a phase difference is generated for each microwave radiated from the first and second power feeding units for each variable period, and the heating distribution of the object to be heated changes for each variable period. For this reason, it has the effect of preventing local concentrated heating of the object to be heated and reducing unevenness in heating.

  The microwave processing apparatus of the present invention prevents heating unevenness in an object to be heated by adding only a rotating mechanism for the purpose of stirring the microwave radiated to the heating chamber and processing the wall surface of the heating chamber only by controlling the phase of the microwave. Can be realized.

Configuration diagram of microwave processing apparatus according to Embodiment 1 of the present invention Power detection characteristic diagram of microwave processing apparatus in Embodiment 1 of the present invention Waveform diagram illustrating an example of a phase difference between two signal waves of the microwave processing apparatus according to Embodiment 1 of the present invention (A) Schematic diagram showing an example of microwaves radiated from the instantaneous power supply unit of the microwave processing apparatus according to Embodiment 1 of the present invention. (B) Instantaneous power supply of the microwave processing apparatus according to Embodiment 1 of the present invention. Schematic showing another example of microwaves radiated from the head Control flow chart of microwave processing apparatus in Embodiment 1 of the present invention The characteristic view which shows an example of the period inversely proportional to the output power of the microwave processing apparatus in Embodiment 1 of this invention The block diagram of the microwave processing apparatus in Embodiment 2 of this invention Configuration diagram of the power feeding section of the microwave processing apparatus according to the second embodiment of the present invention

A first invention includes a heating chamber for storing an object to be heated, an oscillating unit for generating microwave power, a power distributing unit for distributing the output of the oscillating unit into a plurality, and a micro output from the power distributing unit. First and second phase control units for controlling the phase of the wave, first and second power amplification units using semiconductor elements for power amplification of the outputs of the first and second phase control units, First and second power feeding units that supply the outputs of the first and second power amplification units to the heating chamber, and supply from the first and second power amplification units to the first and second power feeding units First and second power detectors for detecting incident power and power reflected from the first and second power feeding units to the first and second power amplifying units, the oscillating unit, and the first And a control unit that controls the second phase control unit, the control unit supplying a microphone to the first and second power feeding units As the wave control, the outputs of the first and second power amplification units are operated at a low output before the heating operation is started, and the oscillation frequency of the oscillation unit is changed within a predetermined frequency range to change the first and second A search is made for conditions under which the reflected power detected by the power detection unit is minimized, and the outputs of the first and second power amplification units are shifted to a heating operation under the searched conditions, and a heating operation is performed. In addition, the phases of the first and second phase control units are varied in a cycle inversely proportional to the incident power supplied to the first and second power feeding units, and each of the power distribution units is changed for each of the varied cycles. The phase difference in the microwave output is controlled for each predetermined combination that is an integral multiple of 90 degrees, and each of the radiation radiated from the first and second power feeding units for each variable period Phase difference with respect to microwaves Occurs, whereby since the heating distribution of the object to be heated in each cycle and the variable is changed, has the effect of reducing uneven heating as well as prevent local concentration heating of the article to be heated.

  In particular, according to a second aspect of the present invention, in the first aspect of the present invention, the power feeding unit has a single configuration having first and second feeding points for feeding the microwaves output from the first and second power amplification units. Accordingly, for example, when the first and second feeding points are arranged at positions where a predetermined offset distance is provided from the intersection of two orthogonal axes, microwaves radiated from one feeding point By setting the phase of the microwave radiated from another different feeding point to a phase difference of ± 90 degrees with respect to the reference phase, the microwave in a circularly polarized state can be radiated. Therefore, it is possible to realize efficient emission of microwaves to the object to be heated and cost reduction by reducing the number of members of the power feeding unit.

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

(Embodiment 1)
FIG. 1 is a configuration diagram of a microwave processing apparatus according to the first embodiment of the present invention.

  In FIG. 1, a microwave generator 11 generates microwave power, and includes an oscillation unit 12 configured using a semiconductor element, a power distribution unit 13 that distributes the output of the oscillation unit 12 into two, and a power distribution unit 13. Semiconductor elements that amplify the outputs of the first phase control unit 14a and the second phase control unit 14b, the first phase control unit 14a, and the second phase control unit 14b, respectively, that delay the phase of the output microwave. The microwave outputs amplified by the first power amplification unit 15a and the second power amplification unit 15b, the first power amplification unit 15a and the second power amplification unit 15b configured using the The first power amplifying unit 1 and the first power amplifying unit 1 that radiate the first power feeding unit 17a and the second power feeding unit 17b, the power reflected from the first power feeding unit 17a to the first power amplifying unit 15a a first power detection unit 18a for detecting incident power supplied from a to the first power supply unit 17a, power reflected from the second power supply unit 17b to the second power amplification unit 15b, and second power amplification A second power detection unit 18b that detects incident power supplied from the unit 15b to the second power feeding unit 17b, and reflected power and incidence detected by the first power detection unit 18a and the second power detection unit 18b. It is comprised with the control part 19 which controls the microwave generator 11 with electric power.

  Further, the microwave processing apparatus of the present invention has a heating chamber 16 having a substantially rectangular parallelepiped structure in which the object to be heated 20 is accommodated.

  The heating chamber 16 includes a left wall surface, a right wall surface, a bottom wall surface, an upper wall surface, a back wall surface using a metal material, an open / close door (not shown) that opens and closes to store the object to be heated 20, and the object to be heated 20. And a mounting table 21 on which the microwaves to be supplied are confined inside.

  Then, the output of the microwave generator 11 is transmitted, and the first power feeding unit 17 a and the second power feeding unit 17 b that radiate the microwave into the heating chamber 16 are arranged on the wall surface constituting the heating chamber 16. Yes.

  In the present embodiment, the first power feeding unit 17a and the second power feeding unit 17b are illustrated on the bottom surface of the heating chamber 16, but the arrangement of the power feeding unit is not limited to the present embodiment. Alternatively, the heating chamber 16 may be disposed on any one of the wall surfaces.

The first power amplifying unit 15a and the second power amplifying unit 15b constitute a circuit with a conductor pattern formed on one side of a dielectric substrate made of a low dielectric loss material, and are semiconductor elements that are amplifying elements. 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 path connecting each functional block forms a transmission circuit having a characteristic impedance of about 50Ω by a conductor pattern provided on one side of a dielectric substrate.

  The first power detection unit 18a and the second power detection unit 18b are so-called reflected wave power and first power transmitted from the heating chamber 16 side to the first power amplification unit 15a and the second power amplification unit 15b side. The so-called incident power transmitted from the first power amplifying unit 15a and the second power amplifying unit 15b to the heating chamber 16 side is extracted. The power coupling degree is, for example, about −40 dB, and the reflected power and the incident power are reduced. Extract 1 / 10,000 power. The power signals are rectified by a detection diode (not shown), smoothed by a capacitor (not shown), and the output signal is input to the control unit 19.

  The control unit 19 includes heating information obtained from the heating condition of the object to be heated 20 directly input by the user or the heating state of the object to be heated 20 during heating, and the first power detection unit 18a and the second power detection unit. Based on the detection information from 18b, the driving power supplied to each of the oscillating unit 12, the first power amplifying unit 15a, and the second power amplifying unit 15b, which are components of the microwave generator 11, is controlled and heated. The object to be heated 20 accommodated in the chamber 16 is optimally heated.

  Further, the microwave generator 11 is mainly provided with heat radiating means (not shown) for radiating the heat generated by the semiconductor elements provided in the first power amplifying unit 15a and the second power amplifying unit 15b.

  FIG. 2 is a power detection characteristic diagram of the microwave processing apparatus according to the first embodiment of the present invention, and the frequency of the total sum of reflected power detected by the first power detection unit 18a and the second power detection unit 18b. It is a figure which shows an example which graphed the characteristic.

  The control unit 19 controls the oscillation frequency condition of the oscillation unit 12 that minimizes the reflected power (the operating frequency is f_opt in the figure) and oscillates output so that an output corresponding to the input heating condition is obtained. To control.

  As a result, the first power amplification unit 15a and the second power amplification unit 15b output predetermined microwave power. The output is transmitted to the first power supply unit 17 a and the second power supply unit 17 b and radiated into the heating chamber 16.

  By obtaining the condition that the reflected power is minimum in this way, the reflected power during the heating operation that outputs a predetermined power can be reduced and the heating operation can be performed. Therefore, the efficiency of the microwave energy with respect to the object to be heated Absorption can be promoted and the heating time can be shortened.

  Next, the characteristics of the phase control in the microwave processing apparatus will be described with reference to FIGS. 3, 4 (a), and 4 (b).

  FIG. 3 is a diagram illustrating an example of a phase difference between two signal waves of the microwave processing apparatus according to the first embodiment of the present invention. As a premise, the amplitude of the signal wave is A, the frequency is f [Hz], the time at a certain instant is t [s], the angular frequency is ω = 2πf [rad / s], the angle at a certain instant is ωt [rad], the period Is defined as T = 1 / f [s], the phase difference is defined as φa and φb, the signal wave 1 is represented by fa (t) = A · sin (ωt + φa), and the signal wave 2 is represented by fb (t) = A · sin ( It is expressed using an equation as ωt + φb).

Here, assuming that the phase difference between the two signal waves is {φa, φb} = {0, 0}, ie, there is no phase difference between the signal wave 2 and the signal wave 1, the amplitude of the two signal waves is Exactly the same behavior with respect to time at a certain instant.

  Next, when the phase difference between the two signal waves is {φa, φb} = {0, −π / 2}, that is, the phase difference between the signal wave 1 and the signal wave 2 is −π / 2 The amplitudes of the two signal waves behave differently over time at a certain instant.

  For example, when the time at a certain instant is t = 0 [s], the amplitude of the signal wave 1 is fa (0) = A · sin (0 + 0) = 0, but the amplitude of the signal wave 2 is fb (0) = A · sin (0 + (− π / 2)) = − A, and the two signal waves have different amplitudes.

  Therefore, it is clear that setting the phase difference between the two signal waves shows different behaviors in the amplitude.

  FIG. 4 (a) is a diagram showing an example of microwaves radiated from the power supply unit at the moment of the microwave processing apparatus according to the first embodiment of the present invention, and FIG. 4 (b) is a diagram illustrating the first embodiment of the present invention. It is a figure which shows the other example of the microwave radiated | emitted from the electric power feeding part in the moment of the microwave processing apparatus in a form. It is a figure which shows an example of the image of the microwave radiated | emitted from a electric power feeding part in the time in each instant.

  4 (a) and FIG. 4 (b), the microwave radiated from the first power supply portion 17a is represented by fa (t) as in the description of the signal wave 1 and the signal wave 2 in FIG. = A · sin (ωt + φa), and the microwave radiated from the second power supply unit 17b is expressed as fb (t) = A · sin (ωt + φb) using a mathematical formula.

  In FIG. 4A, the phase difference between two microwaves is {φa, φb} = {0, 0}, that is, the microwaves radiated from the first power supply unit 17a are compared with those from the second power supply unit 17b. This is a case where there is no phase difference between the radiating microwaves, and since fa (t) = fb (t), the radiation from the first power feeding unit 17a and the second power feeding unit 17b is performed at any instant. The amplitude of each of the microwaves to be shown shows the same behavior and also acts on the object to be heated 20 at the same time.

  In FIG. 4B, the phase difference between the two microwaves is {φa, φb} = {0, −π / 2}, that is, the second power supply for the microwaves radiated from the first power supply unit 17a. This is a case where the phase difference of the microwaves radiated from the unit 17b is −π / 2, and since fa (t) ≠ fb (t), the first feeding unit 17a and the first feeding unit 17a 2 shows a behavior in which the amplitudes of the microwaves radiated from the two power supply portions 17b are different, and also acts on the object to be heated 20 at different times.

  The operation and action of the microwave processing apparatus configured as described above will be described below with reference to FIG. FIG. 5 is a control flowchart of the microwave processing apparatus according to the first embodiment of the present invention.

  In FIG. 5, first, the object to be heated 20 is stored in the heating chamber 16, heating conditions are input from an operation unit (not shown), and a heating start signal is transmitted to the control unit 19 (step S11).

  Thereafter, the control unit 19 operates a drive power source (not shown) based on the information transmitted from step S11, and supplies power to the oscillation unit 12 (step S12).

In the next step S13, the oscillation frequency of the oscillation unit 12 is set to the lowest frequency, for example, 2400M.
A voltage signal to be set to Hz is supplied, and each phase of the first phase control unit 14a and the second phase control unit 14b is set to a first phase in a predetermined combination, and oscillation starts, and thereafter The drive power supply is controlled to operate the first power amplification unit 15a and the second power amplification unit 15b. At this time, the first power amplification unit 15a and the second power amplification unit 15b output a first output power, for example, a microwave of less than 10 W.

  In the next step 14, the total power (Pf) of incident power supplied to the first power supply unit 17a and the second power supply unit 17b and the first power detection from the first power supply unit 17a and the second power supply unit 17b. The total sum (Pr) of the reflected power returning to the unit 18a and the second power detection unit 18b is detected by the first power detection unit 18a and the second power detection unit 18b, and the detected value is stored in the control unit 19 To do.

  In the next step 15, it is determined whether or not the oscillation frequency has reached the maximum frequency, for example, 2500 MHz. If the frequency does not reach 2500 MHz, the process proceeds to step S16. After adding a predetermined scan frequency pitch, for example, 1 MHz, to the oscillation frequency, a microwave is output at the updated oscillation frequency, and the process proceeds again to step S14 and step S15. When the frequency reaches 2500 MHz, the process proceeds to step S17, and the microwave output by the first output power is stopped.

  In the next step S18, the Pr / Pf characteristic using the frequency as a variable is calculated from the detected values of the total sum of incident power (Pf) and the total sum of reflected power (Pr) of each frequency stored in the control unit 19.

  This Pr / Pf characteristic has a unit of percent:%, and the smaller the value, the larger the power absorbed by the article 20 to be heated. Therefore, the first power supply unit 17a and the second power supply unit 17b The reflected power returning to the power detection unit 18a and the second power detection unit 18b is small, which means that the heating efficiency for the object to be heated 20 is high.

  On the other hand, when Pr / Pf is large, the power absorbed by the object to be heated 20 is small, so the first power detection unit 18a and the second power detection from the first power supply unit 17a and the second power supply unit 17b. This means that the reflected power returning to the portion 18b is large and the heating efficiency is low.

  In the next step 19, for the Pr / Pf characteristic calculated in the previous step S18, the frequency at which the Pr / Pf value is minimum is set as the heating frequency.

  In the next step S20, the second output power, for example, the microwave power with the incident power of Pf = 200 [W] is output, and the microwave heating is started.

  In the next step S21, the respective phases of the first phase control unit 14a and the second phase control unit 14b are summed (Pf) of the incident power supplied to the first power supply unit 17a and the second power supply unit 17b. The process proceeds to step 22 after a period inversely proportional to e.g., 5 seconds has elapsed.

  Hereinafter, the period is referred to as a phase switching period (Tp) [s].

  FIG. 6 is a diagram illustrating an example of a cycle inversely proportional to the output power of the microwave processing apparatus according to the first embodiment of the present invention, and illustrates a phase switching cycle (Tp).

  In FIG. 6, the horizontal axis of the graph is the sum (Pf) [W] of the incident power supplied to the first power supply unit 17a and the second power supply unit 17b, and the vertical axis is the phase switching period (Tp) [s]. is there.

  FIG. 7 shows a case where the sum of incident power (Pf) and the phase switching period (Tp) are inversely proportional. For example, the product of the sum of incident power (Pf) and the phase switching period (Tp) is 1000. .

  By making the phase switching period (Tp) inversely proportional to the total incident power (Pf), the amount of power supplied to the first power feeding unit 17a and the second power feeding unit 17b per phase switching period (Tp) The sum, that is, the product of the total incident power (Pf) and the phase switching period (Tp) is constant regardless of the total incident power (Pf).

  By determining the phase switching period (Tp) from the relationship inversely proportional to the total incident power (Pf), the temperature of the heated part of the object to be heated can be increased while the object to be heated is heated with each phase combination. It is possible to equalize and reliably promote uniform heating of the object to be heated.

  After reaching the phase switching cycle, the process proceeds to step S22. If the object to be heated 20 satisfies the heating condition set before heating, the process proceeds to step S24, and if not, the process proceeds to step S23.

  In step S23, the phase of each of the first phase control unit 14a and the second phase control unit 14b is reset according to a predetermined combination that is an integral multiple of 90 degrees.

  For example, assuming that the predetermined combination of the phases is two phases of -90 degrees and 90 degrees, and that the first phase is -90 degrees and the second phase is 90 degrees, The phase is reset to 90 degrees which is the second phase.

  In the second step 23, the first phase is reset to -90 degrees, and thereafter, the first phase of -90 degrees and the second phase of 90 degrees are alternately reset every phase switching period. . In step S24, since it is determined in the previous step 22 that the heating condition of the article to be heated 20 has been satisfied, the second microwave power is stopped and the heating of the article to be heated is terminated.

(Embodiment 2)
FIG. 7 is a configuration diagram of a microwave processing apparatus according to the second embodiment of the present invention.

  In FIG. 7, the microwave generator 11 includes an oscillation unit 12 configured using semiconductor elements, a power distribution unit 13 that distributes the output of the oscillation unit 12 in two, and a phase of the microwave output from the power distribution unit 13. 1st electric power comprised using the semiconductor element which amplifies the output of 1st phase control part 14a and 2nd phase control part 14b to delay, and the 1st phase control part 14a and 2nd phase control part 14b, respectively From the power feeding unit 17c and the power feeding unit 17c that radiate the microwave output amplified by the amplification unit 15a and the second power amplification unit 15b and the first power amplification unit 15a and the second power amplification unit 15b into the heating chamber 16. A first power detection unit 18a for detecting the power reflected to the first power amplification unit 15a and the incident power supplied from the first power amplification unit 15a to the power supply unit 17c; A second power detection unit 18b that detects power reflected from the second power amplification unit 15b to the second power amplification unit 15b and incident power supplied from the second power amplification unit 15b to the power supply unit 17c; and a first power detection unit 18a And a control unit 19 that controls the microwave generator 11 based on the reflected power and the incident power detected by the second power detection unit 18b.

  The difference from the first embodiment is that the power feeding unit 17c has first and second power feeding points that feed the microwaves output from the first power amplifying unit 15a and the second power amplifying unit 15b. There is a single configuration.

  FIG. 8 is a diagram for explaining the power feeding unit 17c of the microwave processing apparatus according to the second embodiment of the present invention. The first power feeding point 23a and the second power feeding located at the center-offset distance 22 are shown. It is comprised from the circular single electric power feeding part 2 which has the point 23b. Here, the center-offset distance 22 is referred to as Dco.

  The first feeding point 23a and the second feeding point 23b are arranged at a position where a predetermined Dco is provided from the intersection of two orthogonal axes. In this case, the phase of the microwave radiated from one feeding point is set as a reference, and the phase of the microwave radiated from the other feeding point is set to a phase difference of ± 90 degrees with respect to the reference phase. It becomes possible to radiate a circularly polarized microwave. Thereby, the microwave can be efficiently radiated to the object to be heated, and the cost can be reduced by reducing the number of members of the power feeding unit.

  As described above, the microwave processing apparatus according to the present embodiment radiates from the first power feeding unit 17a and the second power feeding unit 17b or the power feeding unit 17c having a circular single configuration every phase switching period. A phase difference occurs with respect to the microwaves, and this changes the heating distribution of the object to be heated at each variable period, thereby preventing localized concentrated heating of the object to be heated and improving uneven heating. It becomes.

  As described above, the microwave processing apparatus according to the present invention can be uniformly heated only by system control as well as replacement of the existing microwave oven, and therefore, a small heating apparatus or other equipment having severe mechanical constraints, for example, It can also be applied to applications such as integrated assembly into refrigerators and vending machines.

DESCRIPTION OF SYMBOLS 11 Microwave generator 12 Oscillator 13 Power distribution part 14a 1st phase control part 14b 2nd phase control part 15a 1st power amplification part 15b 2nd power amplification part 16 Heating chamber 17a 1st electric power feeding part 17b 2nd electric power feeding part 17c Electric power feeding part 18a 1st electric power detection part 18b 2nd electric power detection part 19 Control part 20 To-be-heated object 21 Mounting stand 22 Center-offset distance 23a 1st electric power feeding point 23b 2nd electric power feeding point

Claims (2)

A heating chamber for storing an object to be heated;
An oscillator that generates microwave power;
A power distribution unit that distributes the output of the oscillation unit to a plurality of;
First and second phase control units that control the phase of the microwave output from the power distribution unit, and first and second semiconductor devices that use the semiconductor elements that amplify the power of the outputs of the first and second phase control units, A second power amplification unit;
First and second power feeding units that supply the outputs of the first and second power amplification units to the heating chamber;
Incident power supplied from the first and second power amplification units to the first and second power supply units and reflected from the first and second power supply units to the first and second power amplification units. First and second power detection units for detecting power;
A control unit for controlling the oscillation unit and the first and second phase control units;
The control unit operates the outputs of the first and second power amplification units at a low output before starting a heating operation as a control of the microwaves supplied to the first and second power feeding units, and operates in a predetermined frequency range. In which the oscillation frequency of the oscillating unit is changed to search for a condition where the reflected power detected by the first and second power detecting units is minimized, and the first and second power amplifying units are searched under the searched condition. Is shifted to a heating operation by performing a predetermined output operation, and the phase of the first and second phase control units is inversely proportional to the incident power supplied to the first and second power feeding units during the heating operation. And a microwave processing apparatus configured to control every predetermined combination in which a phase difference in each microwave output of the power distribution unit is an integral multiple of 90 degrees for each variable period. The microwave processing apparatus according to claim 1, wherein the power feeding unit has a single configuration including first and second power feeding points that feed microwaves output from the first and second power amplification units.