JP2008034244A - Microwave treatment device and microwave treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave treatment device and a microwave treatment method wherein power conversion efficiency is improved and a microwave generating device can be prevented from being damaged by reflection power. <P>SOLUTION: By controlling a microwave generating part 300 before the main heating of an object, a microcomputer 700 sweeps frequencies of a microwave generated by the microwave generating part 300 across the total frequency band of 2,400 MHz to 2,500 MHz, and memorizes a relation between the reflection power and the frequencies detected by a reflection power detecting device 600. Then, the frequency when the minimum reflection power is shown from the memorized relation between the reflection power and the frequency is extracted as the main heating frequency. Afterwards, the microcomputer 700 generates microwaves of the main heating frequency by the microwave generating part 300 at the main heating of the object, and radiates them into a cabinet 501 from an antennae A1. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a microwave processing apparatus and a microwave processing method for processing an object with microwaves.

  Conventionally, microwave generators using semiconductor elements have been proposed in place of magnetrons generally used as microwave generators. According to the microwave generator using the semiconductor element, the frequency of the microwave can be easily adjusted with a small and inexpensive configuration. As described above, Patent Document 1 discloses a high-frequency heating device including a microwave generator using a semiconductor element.

In the high-frequency heating device of Patent Document 1, the microwave frequency is swept in a predetermined frequency band, and the microwave frequency when the reflected power shows the minimum value is stored. And the microwave of the memorize | stored frequency is radiated | emitted from the antenna in a heating chamber, and a target object is heated. Thereby, power conversion efficiency improves.
JP-A-56-96486

  The semiconductor element is used in a state where the heat dissipation member is in contact. When the semiconductor element generates heat due to the reflected power, heat dissipation is performed by the heat dissipation member.

  However, when a very large reflected power is generated when the microwave frequency is swept, the heat generated by the reflected power may exceed the heat dissipation capability of the heat dissipation member. In this case, the semiconductor element may be damaged.

  An object of the present invention is to provide a microwave processing apparatus and a microwave processing method capable of improving power conversion efficiency and preventing damage to the microwave generation apparatus due to reflected power.

  (1) A microwave processing apparatus according to a first aspect of the present invention is a microwave processing apparatus for processing an object using a microwave, and is generated by a microwave generating means for generating a microwave, and the microwave generating means. A radiating unit that radiates the target microwave to the object, a detection unit that detects reflected power from the radiating unit, and a control unit that controls the microwave generation unit, the control unit prior to processing the object For processing the object based on the frequency at which the reflected power detected by the detecting means is minimized or minimized by radiating the microwave from the radiating unit to the object while changing the microwave frequency by the microwave generating means. The microwave frequency is determined as the processing frequency, and the microwave of the determined processing frequency is generated by the microwave generating means when the object is processed.

  In this microwave processing apparatus, the microwave is radiated from the radiating unit to the object while the frequency of the microwave is changed by the microwave generating means before the object is processed. At this time, the frequency of the microwave for processing the object is determined as the processing frequency based on the frequency at which the reflected power from the radiating portion detected by the detecting means is minimized or minimized. At the time of processing the object, a microwave having a determined processing frequency is generated by the microwave generating means.

  As described above, since the microwave having the processing frequency determined based on the frequency at which the reflected power from the radiating unit is minimized or minimized is used for processing the object, the reflected power generated when the object is processed is reduced. The Thereby, the power conversion efficiency of the microwave processing apparatus is improved.

  Further, even when the microwave generating means generates heat due to the reflected power, the amount of generated heat is reduced. As a result, breakage and failure of the microwave generation means due to the reflected power are prevented.

  (2) The control unit may determine, as the processing frequency, one or a plurality of frequencies at which the reflected power detected by the detection unit is minimized or minimized before processing the object.

  In this case, the reflected power generated during processing of the object can be sufficiently reduced. Thereby, the power conversion efficiency of the microwave processing apparatus is sufficiently improved.

  Further, even when the microwave generating means generates heat due to the reflected power, the amount of generated heat is sufficiently reduced. As a result, breakage and failure of the microwave generation means due to the reflected power are sufficiently prevented.

  (3) The control means sets the power of the microwave radiated from the radiating unit to the target before processing the target to a value smaller than the power of the microwave radiated from the radiating unit to the target at the time of processing the target. It may be set.

  In this case, the microwave power radiated from the radiating unit to the target object is smaller than the microwave power radiated during the processing of the target object while changing the microwave frequency before the target part processing. It is possible to prevent the object from being processed by microwaves having a large electric power before the object is processed. Thereby, power consumption before the processing of the object is reduced, and the object is prevented from being processed under undesired conditions.

  (4) The microwave generating means includes heat radiating means, and the power of the microwave radiated from the radiating unit to the object before processing the object is set to a value lower than the energy that the heat radiating means can radiate. Also good.

  In this case, before the object is processed, the heat generated due to the reflected power from the radiating unit when the microwave is radiated from the radiating unit to the object while changing the frequency of the microwave by the microwave generating unit. Is sufficiently dissipated by the heat dissipation means. Thereby, breakage and failure of the microwave generation means due to the reflected power are reliably prevented. In addition, power consumption before processing the object is reduced.

  (5) During the processing of the object, the control means causes the microwave generation means to radiate the microwave to the object while changing the microwave frequency, and the reflected power detected by the detection means is minimized or Based on the minimum frequency, the frequency of the microwave for processing the object is determined as a new processing frequency, and the frequency update processing is performed in which the microwave of the determined new processing frequency is generated by the microwave generation means. May be.

  Here, the reflected power generated during the processing of the target object may change depending on the processing state of the target object. Therefore, the frequency update process is performed during the processing of the object, whereby the object is processed with the microwave having a new processing frequency corresponding to the processing state of the object. Thereby, the reflected power from the radiation part is always reduced.

  Thereby, the fall of the power conversion efficiency of the microwave processing apparatus during the process of a target object is prevented. Further, breakage and failure of the microwave processing means can be prevented.

  (6) The control means may perform the frequency update process when the reflected power detected by the detection means exceeds a predetermined threshold during the processing of the object.

  In this case, when the reflected power from the radiating unit exceeds a threshold due to a change in the state of the object, a frequency update process is performed, and a new processing frequency of the microwave radiated to the object is determined. And the microwave of the determined new processing frequency is radiated | emitted to a target object. This reliably prevents a decrease in power conversion efficiency of the microwave processing apparatus due to a change in the state of the object, and also prevents damage and failure of the microwave generation means.

  (7) The control means may perform the frequency update process every time a predetermined time elapses during the processing of the object.

  In this case, even when the reflected power from the radiating unit increases due to a change in the state of the object, frequency update processing is performed every predetermined time, and a new processing frequency of the microwave radiated to the object is determined. . And the microwave of the determined new processing frequency is radiated | emitted to a target object. This reliably prevents a decrease in power conversion efficiency of the microwave processing apparatus due to a change in the state of the object, and also prevents damage and failure of the microwave generation means.

  (8) In the frequency update process, the control means may change the frequency of the microwave by the microwave generation means within a certain range including the processing frequency determined immediately before.

  In this case, the time required for the frequency update process is shortened. Thereby, the influence which the frequency update process has on the object being processed can be minimized.

  (9) A plurality of radiation units are provided, the detection unit detects reflected power from each of the plurality of radiation units, and the control unit changes the frequency of the microwave by the microwave generation unit before processing the object. While radiating microwaves to a target from a plurality of radiating sections, the microwaves for processing the target are based on frequencies at which reflected power from the plurality of radiating sections detected by the detecting means is minimized or minimized, respectively. The frequency may be determined as the processing frequency.

  In this case, the frequency of the microwave for processing the object is determined as the processing frequency based on the frequency at which the reflected power from the plurality of radiating portions detected by the detection means is minimized or minimized.

  As described above, since the microwave having the processing frequency determined based on the frequency at which the reflected power from the radiating unit is minimized or minimized is used for processing the object, the reflected power generated when the object is processed is reduced. The Thereby, the power conversion efficiency of the microwave processing apparatus is improved.

  Further, even when the microwave generating means generates heat due to the reflected power, the amount of generated heat is reduced. As a result, breakage and failure of the microwave generation means due to the reflected power are prevented.

  (10) The treatment of the object may be a heat treatment, and the microwave processing apparatus may further include a heating chamber that accommodates the object for heating.

  In this case, the object can be heat-treated by accommodating the object in the heating chamber.

  (11) A microwave processing method according to a second aspect of the present invention is a microwave processing method for processing an object using microwaves, and the radiation unit changes the frequency of the microwave before processing the object. The step of detecting the reflected power from the radiating part and radiating the microwave from the object to the object, and processing the frequency of the microwave for processing the object based on the frequency at which the detected reflected power is minimized or minimized A step of determining the frequency, and a step of generating a microwave of the determined processing frequency when the object is processed.

  In this microwave processing method, the microwave is radiated from the radiating unit to the object while the frequency of the microwave is changed before the object is processed, and the reflected power from the radiating unit is detected. Based on the frequency at which the reflected power from the detected radiation part is minimized or minimized, the frequency of the microwave for processing the object is determined as the processing frequency. During processing of the object, a microwave with a determined processing frequency is generated.

  As described above, since the microwave having the processing frequency determined based on the frequency at which the reflected power from the radiating unit is minimized or minimized is used for processing the object, the reflected power generated when the object is processed is reduced. The Thereby, the power conversion efficiency for generating a microwave and processing a target object is improved.

  Further, even when the microwave generating means for generating microwaves due to the reflected power generates heat, the amount of generated heat is reduced. As a result, breakage and failure of the microwave generation means due to the reflected power are prevented.

  (12) The microwave processing method includes detecting a reflected power from the radiation unit and radiating a microwave from the radiation unit to the target while changing the frequency of the microwave during the processing of the target object. Determining a microwave frequency for processing the object as a new processing frequency based on a frequency at which the reflected power is minimized or minimized, and generating a microwave with the determined new processing frequency. May be further provided.

  Here, the reflected power generated during the processing of the target object may change depending on the processing state of the target object. Therefore, the processing frequency of the microwave is newly determined during the processing of the object, and the processing of the object is performed with the microwave having the new processing frequency. Thereby, the reflected power from the radiation part is always reduced.

  Thereby, the fall of the power conversion efficiency of the microwave processing apparatus during the process of a target object is prevented. Further, breakage and failure of the microwave processing means are prevented.

  According to the present invention, the microwave having the processing frequency determined based on the frequency at which the reflected power from the radiating unit is minimized or minimized is used for the processing of the object. Therefore, the reflected power generated during the processing of the object is reduced. Reduced. Thereby, the power conversion efficiency of the microwave processing apparatus is improved.

  Further, even when the microwave generating means generates heat due to the reflected power, the amount of generated heat is reduced. As a result, breakage and failure of the microwave generation means due to the reflected power are prevented.

  Hereinafter, a microwave processing apparatus and a microwave processing method according to an embodiment of the present invention will be described. In the following description, a microwave oven will be described as an example of a microwave processing apparatus.

[1] First Embodiment (1-1) Outline of Configuration and Operation of Microwave Oven FIG. 1 is a block diagram showing a configuration of a microwave oven according to the first embodiment. As shown in FIG. 1, a microwave oven 1 according to the present embodiment includes a microwave generator 100 and a housing 501. An antenna A1 is provided in the housing 501.

  Further, the microwave generation device 100 includes a voltage supply unit 200, a microwave generation unit 300, a microwave amplification unit 400, a reflected power detection device 600, and a microcomputer 700. The microwave generator 100 is connected to a commercial power source via the power plug 10.

  In the microwave generation apparatus 100, the voltage supply unit 200 converts an AC voltage supplied from a commercial power source into a variable voltage and a DC voltage, applies the variable voltage to the microwave generation unit 300, and supplies the DC voltage to the microwave amplification unit 400. To give.

  The microwave generator 300 generates a microwave based on the variable voltage supplied from the voltage supply unit 200. The microwave amplifying unit 400 operates with a DC voltage supplied from the voltage supply unit 200 and amplifies the microwave generated by the microwave generating unit 300. Details of configurations and operations of the voltage supply unit 200, the microwave generation unit 300, and the microwave amplification unit 400 will be described later.

  The reflected power detection device 600 includes a detection diode, a directional coupler, a terminator, and the like, and applies the microwave amplified by the microwave amplifier 400 to the antenna A1 provided in the housing 501. As a result, microwaves are radiated from the antenna A <b> 1 within the housing 501.

  At this time, the reflected power is applied from the antenna A1 to the reflected power detection device 600. The reflected power detection apparatus 600 gives a reflected power detection signal corresponding to the magnitude of the given reflected power to the microcomputer 700.

  A temperature sensor TS for measuring the temperature of the object is provided in the housing 501. The measured temperature value of the object by the temperature sensor TS is given to the microcomputer 700.

  The microcomputer 700 controls the voltage supply unit 200 and the microwave generation unit 300. Details will be described later.

(1-2) Details of Configuration of Microwave Generation Device FIG. 2 is a schematic side view of the microwave generation device 100 constituting the microwave oven 1 of FIG. 1, and FIG. 3 is a diagram of the microwave generation device 100 of FIG. It is the figure which showed typically the circuit structure of these.

  Based on FIG. 2 and FIG. 3, the detail of each structure part of the microwave generator 100 is demonstrated. 2 and 3, illustration of the reflected power detection device 600 and the microcomputer 700 is omitted.

  2 includes a rectifier circuit 201 (FIG. 3) and a voltage control device 202 (FIG. 3). Voltage control device 202 includes a transformer 202a and a voltage control circuit 202b. The rectifier circuit 201 and the voltage control device 202 are accommodated in the metal case IM1 (FIG. 2) in a state of being sealed with an insulating material such as resin.

  The microwave generation unit 300 of FIG. 2 includes heat radiating fins 301 and a circuit board 302. A microwave generator 303 shown in FIG. 3 is formed on the circuit board 302. The circuit board 302 is provided on the heat radiating fins 301. The circuit board 302 and the microwave generator 303 are accommodated in the metal case IM2 in a state of being sealed with an insulating material on the heat radiation fin 301. The microwave generator 303 is configured by a circuit element such as a transistor, for example.

  The microwave generator 303 is connected to the microcomputer 700 of FIG. Thereby, the operation of the microwave generator 303 is controlled by the microcomputer 700.

  2 includes a heat radiation fin 401 and a circuit board 402. On the circuit board 402, the three amplifiers 403, 404, and 405 of FIG. 3 are formed. The circuit board 402 is provided on the heat radiation fin 401. The circuit board 402 and the amplifiers 403, 404, and 405 are accommodated in the metal case IM3 in a state of being sealed with an insulating material on the heat radiation fin 401. The amplifiers 403, 404, and 405 are configured by high heat resistance and high breakdown voltage semiconductor elements such as transistors using GaN (gallium nitride), SiC (silicon carbide), or the like.

  As shown in FIG. 3, the output terminal of the microwave generator 303 is connected to the input terminal of the amplifier 403 via the line L1 formed on the circuit board 302, the coaxial cable CC1, and the line L2 formed on the circuit board 402. Has been. Note that the coaxial cable CC1 and the line L2 are connected at an insulation coupling portion MC.

  The output terminal of the amplifier 403 is connected to the input terminal of the power distributor 406 via a line L 3 formed on the circuit board 402. The power distributor 406 distributes the power input from the amplifier 403 via the line L3 and outputs it.

  Two output terminals of the power distributor 406 are connected to respective input terminals of the amplifier 404 and the amplifier 405 through lines L4 and L5 formed on the circuit board 402.

  The output terminals of the amplifier 404 and the amplifier 405 are connected to the input terminal of the power combiner 407 via lines L6 and L8 formed on the circuit board 402. The power combiner 407 combines and adds the input powers and outputs the combined power. An output terminal of the power combiner 407 is connected to one end of the coaxial cable CC <b> 2 via a line L <b> 7 formed on the circuit board 402. The other end of the coaxial cable CC2 is connected to an antenna A1 provided in the housing 501. The coaxial cable CC2 and the line L7 are connected to each other at the insulating connection part MC.

The AC voltage _VCC is supplied from the commercial power source PS to the pair of input terminals of the rectifier circuit 201 and the primary winding of the transformer 202a. The AC voltage _VCC is, for example, 100 (V). A pair of output terminals of the rectifier circuit 201 is connected to a power line LV1 on the high potential side and a power line LV2 on the low potential side.

The rectifier circuit 201 rectifies the AC voltage VCC _supplied from the commercial power source PS, and applies the DC voltage V _DD between the power supply lines LV1 and LV2. The DC voltage V _DD is, for example, 140 (V). The power terminals of the amplifiers 403, 404, and 405 are connected to the power line LV1, and the ground terminals of the amplifiers 403, 404, and 405 are connected to the power line LV2.

The secondary winding of the transformer 202a is connected to a pair of input terminals of the voltage control circuit 202b. Trans 202a is down the AC voltage _{V CC.} The voltage control circuit 202b provides the microwave generator 303 with a variable voltage _VVA that can be arbitrarily adjusted from the AC voltage stepped down by the transformer 202a. The variable voltage _VVA is a voltage that can be adjusted between 0 and 10 (V), for example.

The microwave generator 303 generates a micro wave based on the variable voltage _{V VA} supplied from the voltage control circuit 202b. The microwave generated by the microwave generator 303 is given to the amplifier 403 via the line L1, the coaxial cable CC1, and the line L2.

  The amplifier 403 amplifies the microwave power supplied from the microwave generator 303. The microwave amplified by the amplifier 403 is given to the amplifiers 404 and 405 through the line L3, the power distributor 406, and the lines L4 and L5.

  The amplifiers 404 and 405 amplify the microwave power supplied from the amplifier 403. The microwaves amplified by the amplifier 404 and the amplifier 405 are input to the power combiner 407 via the lines L6 and L8, respectively, and the power is added by the power combiner 407 to be output, via the line L7 and the coaxial cable CC2. It is given to the antenna A1. Microwaves applied to the antenna A 1 from the amplifiers 404 and 405 are radiated into the housing 501.

(1-3) Microcomputer Control Procedure FIGS. 4 and 5 are flowcharts showing the control procedure of the microcomputer 700 of FIG.

  The microcomputer 700 in FIG. 1 performs the following microwave processing when the heating of the object is commanded by the user's operation.

  As shown in FIG. 4, the microcomputer 700 first starts a measurement operation by a timer built in itself (step S11). 1 is set as the output power of the microwave oven 1 by controlling the microwave generator 300 of FIG. 1 (step S12). The first output power is smaller than the second output power described later. A method for determining the first output power will be described later.

  Next, the microcomputer 700 sweeps (sweeps) the frequency of the microwave generated by the microwave generation unit 300 over the entire frequency band of 2400 MHz to 2500 MHz used in the microwave oven 1, and the reflected power detection device of FIG. 1. The relationship between the reflected power detected by 600 and the frequency is stored (step S13). This frequency band is called an ISM (Industrial Scientific and Medical) band.

  Note that the microcomputer 700 stores only the relationship between the reflected power and the frequency when the reflected power shows a minimum value, instead of storing the relationship between the reflected power and the frequency in the entire frequency band when sweeping the microwave frequency. May be. In this case, the use area of the storage device in the microcomputer 700 can be reduced.

  Subsequently, the microcomputer 700 performs frequency extraction processing for extracting a specific frequency from the ISM band (step S14).

  In this frequency extraction process, for example, a specific reflected power (for example, a minimum value) is identified from the stored reflected power, and the frequency when the reflected power is obtained is extracted as the main heating frequency. A specific example will be described later.

  When the microcomputer 700 stores a plurality of sets of only the relationship between the reflected power and the frequency when the reflected power shows a minimum value, a specific frequency is extracted from the stored frequencies as the main heating frequency. Is done.

  Next, the microcomputer 700 sets the predetermined second output power as the output power of the microwave oven 1 (step S15).

  The second output power is power for heating the object arranged in the housing 501 in FIG. 1 and corresponds to the maximum output power (rated output power) of the microwave oven 1. For example, when the rated output power of the microwave oven 1 is 950 W, the second output power is predetermined as 950 W.

  Then, the microcomputer 700 radiates the microwave of the main heating frequency from the antenna A1 into the housing 501 with the second output power (step S16). Thereby, the target object arrange | positioned in the housing | casing 501 is heated (main heating).

  Thereafter, the microcomputer 700 determines whether or not the temperature of the object detected by the temperature sensor TS of FIG. 1 has reached a target temperature (for example, 70 ° C.) (step S17). Note that the target temperature may be fixedly set in advance, or may be arbitrarily set manually by the user.

  When the temperature of the object does not reach the target temperature, the microcomputer 700 determines whether or not the reflected power detected by the reflected power detection device 600 exceeds a predetermined threshold value (step S18). A method for determining the threshold will be described later.

  If the reflected power does not exceed a predetermined threshold, the microcomputer 700 determines whether or not a predetermined time (for example, 10 sec) has elapsed since the start of the timer measurement operation in step S11 based on the measurement value by the timer. Is determined (step S19).

  If the predetermined time has not elapsed, the microcomputer 700 repeats the operations of steps S17 to S19 while maintaining the state where the microwave of the main heating frequency is radiated with the second output power.

  In step S17, when the temperature of the object reaches the target temperature, the microcomputer 700 ends the microwave process.

  If the reflected power exceeds a predetermined threshold value in step S18, the microcomputer 700 returns to the operation in step S11.

  When the predetermined time has elapsed in step S19, the microcomputer 700 resets the timer as shown in FIG. 5 and starts the timer measurement operation again (step S20).

  And the microcomputer 700 sets 1st output power as output power of the microwave oven 1 similarly to step S12 (step S21).

  Subsequently, the microcomputer 700 sets the main heating frequency extracted in step S16 as a reference frequency, and in a certain range of frequency band including the reference frequency (for example, a frequency band within ± 5 MHz from the reference frequency), The frequency of the microwave is partially swept and the relationship between the reflected power detected by the reflected power detection device 600 and the frequency is stored (step S22).

  In this case as well, the microcomputer 700 stores the relationship between the reflected power and the frequency in the partial frequency band when sweeping the microwave frequency, and the reflected power when the reflected power shows a minimum value. Only the relationship with the frequency may be stored. In this case, the use area of the storage device in the microcomputer 700 can be reduced.

  The frequency band to be swept in step S22 is narrower than the frequency band to be swept in step S13, that is, the ISM band. Therefore, the time required for the sweep in step S22 is shortened compared to the time required for the sweep in step S13.

  Next, the microcomputer 700 performs frequency re-extraction processing for extracting a specific frequency again from the frequency band to be swept in step S22 (step S23). This frequency re-extraction process is the same process as the frequency extraction process in step S14.

  Furthermore, the microcomputer 700 sets the second output power described above as the output power of the microwave oven 1 (step S24).

  Then, the microcomputer 700 radiates the microwave of the main heating frequency newly extracted with the second output power from the antenna A1 into the housing 501 (step S25).

  Thereafter, the microcomputer 700 performs the operations of Steps S26 to S28 in the same manner as Steps S17 to S19. If the reflected power exceeds the predetermined threshold value in step S27, the microcomputer 700 returns to the operation in step S11 in FIG. If the predetermined time has elapsed in step S28, the microcomputer 700 returns to the operation of step S20.

(1-4) First Output Power Determination Method As described above, in the microwave oven 1 of FIG. 1, the microwave is generated with the first output power before the object is heated with the second output power. Frequency sweep is performed, and frequency extraction processing is performed. This is due to the following reason.

  The reflected power generated by the microwave radiation changes according to the frequency of the microwave. Here, when the circuit elements constituting the microwave generation unit 300 and the microwave amplification unit 400 in FIG. 3 generate heat due to the reflected power, heat is radiated by the radiation fins 301 and 401 in FIG. If the heat dissipation capacity of the heat dissipation fins 301 and 401 is exceeded, the circuit elements provided on the heat dissipation fins 301 and 401 may generate heat and be damaged.

  Therefore, in the present embodiment, the first output power is determined so that the reflected power does not exceed the heat radiation capability of the heat radiation fins 301 and 401.

  An example of a method for determining the first output power will be described. For example, it is assumed that the rated output power of the microwave oven 1 is 950 W and the power conversion efficiency is 65%.

  In this case, in order to set the output power of the microwave oven 1 to 950 W, it is necessary to supply the input power of 1460 W to the microwave oven 1.

  At this time, in the microwave oven 1, an energy loss of 510 W, which is 35% of 1460 W, occurs. Therefore, in this example, the energy loss at this time is regarded as the heat radiation capability of the heat radiation fins 301 and 401, and the output power when the input power of 510 W is supplied to the microwave oven 1 is calculated.

  In this case, 330 W that is 65% of the input power 510 W is the output power of the microwave oven 1. The output power of 330 W obtained in this way is determined as the first output power.

  As a result, even when 510 W input to the microwave oven 1 is all given to the heat radiation fins 301 and 401 as heat energy, all the heat energy is radiated from the heat radiation fins 301 and 401. As a result, the circuit elements provided on the radiation fins 301 and 401 are prevented from generating heat and being damaged.

  In the above example, the first output power may be determined to be 330 W or less, and may be set to 100 W, which is approximately 1/3 of 330 W, or may be set to 50 W, which is approximately 1/6 of 330 W. Good.

  In the above description, the heat radiation capacity of the heat radiation fins 301 and 401 when the rated output power of the microwave oven 1 is 950 W and the power conversion efficiency is 65% is considered to be 510 W. , 401 has a heat dissipation capacity sufficiently larger than 510W.

(1-5) Frequency extraction processing and frequency re-extraction processing (1-5-a)
In the microwave oven 1 according to the present embodiment, a microwave frequency sweep and frequency extraction process is performed before the main heating of the object (see steps S13 and S14 in FIG. 4).

  FIG. 6 is a diagram for explaining a specific example of microwave frequency sweeping and frequency extraction processing.

  FIG. 6A is a graph showing the change in the reflected power when the frequency of the microwave is swept. In FIG. 6A, the vertical axis indicates the reflected power, and the horizontal axis indicates the frequency of the microwave.

  As described above, in the microwave oven 1 according to the present embodiment, the microwave frequency is swept over the entire frequency band of the ISM band before the main heating of the object (see arrow SW1). The microcomputer 700 stores the relationship between the reflected power and the frequency.

  The microcomputer 700 extracts, for example, the frequency f1 when the reflected power is minimum as the main heating frequency by the frequency extraction process.

  Thereby, the microwave of the main heating frequency f1 is radiated from the antenna A1 to the object in the housing 501 with the second output power. As a result, the object can be heated while reducing the reflected power.

  Note that the sweep is performed at 1 msec per 0.1 MHz, for example. In this case, the above sweep over the entire frequency band of the ISM band requires 1 sec.

(1-5-b)
The change in the reflected power depending on the frequency (hereinafter referred to as the frequency characteristic of the reflected power) changes according to the position, size, composition, temperature, and the like of the object in the housing 501. Therefore, when the object is heated by the microwave oven 1 and the temperature of the object rises, the frequency characteristic of the reflected power also changes.

  FIG. 6B shows a graph showing changes in the frequency characteristics of the reflected power due to the object being heated. In FIG. 6B, the vertical axis indicates the reflected power, and the horizontal axis indicates the frequency of the microwave. The frequency characteristic of the reflected power during the sweep before the main heating is indicated by a solid line, and the frequency characteristic of the reflected power when the object is heated by the main heating is indicated by a broken line.

  By changing the frequency characteristic of the reflected power, the frequency at which the reflected power is minimized and minimized changes. In FIG. 6B, the frequency at which the reflected power is minimum when the object is heated is indicated by reference numeral g1.

  Thus, the frequency characteristic of the reflected power changes depending on the temperature of the object. Therefore, in the microwave oven 1 according to the present embodiment, when main heating of an object is performed, a microwave frequency sweep and a frequency re-extraction process are performed every time a predetermined time elapses (step S22 in FIG. 5). (See S23).

  However, the sweep at this time is performed in a frequency band within a range of ± 5 MHz from the reference frequency with the frequency f1 set at the time of the last main heating as a reference frequency (see arrow SW2). Thereby, the frequency g1 at which the reflected power is newly minimized is re-extracted as a new main heating frequency.

  By performing the sweep of the microwave frequency in a partial frequency band within a certain range including the main heating frequency set immediately before, the time required for the sweep is shortened. For example, when the sweep is performed at 1 msec per 0.1 MHz, the time required for the sweep in the frequency band within the range of ± 5 MHz from the reference frequency is 0.1 sec.

  In the present embodiment, frequency sweep and frequency re-extraction processing in a partial frequency band are performed at a predetermined time interval. In this time interval, the frequency characteristic of reflected power is the heating of the object. For example, it is preferably set to 10 sec so as not to change greatly.

(1-6) Threshold of reflected power In the microwave oven 1 according to the present embodiment, it is determined whether or not the reflected power exceeds a predetermined threshold during the main heating of the object (FIG. 4). Step S18 of FIG. 5 and Step S27 of FIG. 5).

  Here, the threshold value is set to a value obtained by adding 50 W to the minimum value of the reflected power detected during the frequency extraction process, for example. Accordingly, when the reflected power increases beyond 50 W from the value at the start of the main heating, the microcomputer 700 sweeps the frequency of the microwave over the entire frequency band of the ISM band and performs the frequency extraction process.

  This prevents the reflected power from becoming significantly large during the main heating of the object. Further, even when the frequency characteristic of the reflected power changes greatly due to the heating of the object, the microwave frequency is swept over the entire frequency band of the ISM band, and the frequency extraction process is performed, so that the reflection is always performed. It becomes possible to reduce electric power.

(1-7) Other examples of frequency extraction processing The frequency extraction processing may be performed as follows. As shown in FIG. 6A, for example, the frequency characteristic of reflected power may have a plurality of minimum values. At this time, the microcomputer 700 may extract the frequencies f1, f2, and f3 respectively corresponding to the plurality of minimum values as the main heating frequency.

  In this case, the microcomputer 700 may sequentially switch the main heating frequencies f1, f2, and f3. For example, the microcomputer 700 sequentially switches the main heating frequencies f1, f2, and f3 every 3 seconds from the start of the main heating of the object.

  In this way, by performing the main heating at a plurality of frequencies corresponding to a plurality of minimum values, even when there are a plurality of minimum values at the same level during the sweep, the main heating of the object is performed with the microwaves of the respective minimum values. It can be carried out.

(1-8) Effect In the microwave oven 1 according to the present embodiment, the frequency of the microwave at which the reflected power generated when the object is heated is minimized by the frequency extraction process before the object is fully heated. Extracted. The power conversion efficiency of the microwave oven 1 is improved by using the extracted frequency as the main heating frequency.

  In the frequency extraction process, the output power of the microwave oven 1 is set to a first output power that is sufficiently smaller than that during main heating. Thus, even when circuit elements constituting the microwave generation unit 300 and the microwave amplification unit 400 generate heat due to the reflected power during the sweep of the microwave frequency, the heat radiation fins 301 and 401 sufficiently radiate heat.

  As a result, the circuit element provided on the radiation fins 301 and 401 is reliably prevented from being damaged by the reflected power.

(1-9) Modified Example In the first embodiment, the second output power is the maximum output power of the microwave oven 1, but the second output power is arbitrarily set manually by the user. Also good.

  Further, in the present embodiment, the microcomputer 700 determines the end of the microwave processing based on the temperature measurement value of the object measured by the temperature sensor TS of FIG. 1, but the microwave processing is performed by the user. You may complete | finish based on the end time set manually.

[2] Second Embodiment A microwave oven according to the second embodiment is different from the microwave oven 1 according to the first embodiment in the following points.

(2-1) Configuration of Microwave Oven and Outline of Operation FIG. 7 is a block diagram showing the configuration of the microwave oven according to the second embodiment. As shown in FIG. 7, in the microwave oven 1 according to the second embodiment, the configuration of the microwave generator 100 and the number of antennas A1 and A2 provided in the housing 501 are related to the first embodiment. Different from microwave oven 1 (FIG. 1).

  In the microwave oven 1 according to the present embodiment, the microwave generation device 100 includes a voltage supply unit 200, two microwave generation units 300 and 310, two microwave amplification units 400 and 410, and two reflected powers. Detection devices 600 and 610 and a microcomputer 700 are provided.

  Here, the configurations of the microwave generation unit 310, the microwave amplification unit 410, and the reflected power detection device 610 are the same as those of the microwave generation unit 300, the microwave amplification unit 400, and the reflected power detection device 600 described in the first embodiment. Is the same.

  The microwave generator 100 is connected to a commercial power source via the power plug 10. In the microwave generator 100, the voltage supply unit 200 converts an AC voltage supplied from a commercial power source into a variable voltage and a DC voltage, applies the variable voltage to the microwave generators 300 and 310, and amplifies the DC voltage by microwave amplification. Parts 400 and 410.

  The microwave generation units 300 and 310 generate microwaves based on the variable voltage supplied from the voltage supply unit 200. The microwave amplifying units 400 and 410 operate with a DC voltage supplied from the voltage supply unit 200 and amplify the microwaves generated by the microwave generating units 300 and 310.

  The reflected power detection devices 600 and 610 include a detection diode, a directional coupler, a terminator, and the like. give. As a result, microwaves are radiated from the antennas A 1 and A 2 in the housing 501.

  At this time, reflected power is applied to the reflected power detection devices 600 and 610 from the antennas A1 and A2. The reflected power detection devices 600 and 610 provide the microcomputer 700 with a reflected power detection signal corresponding to the magnitude of the applied reflected power.

  Similar to the first embodiment, a temperature sensor TS for measuring the temperature of an object is provided in the housing 501. The measured temperature value of the object by the temperature sensor TS is given to the microcomputer 700.

  The microcomputer 700 controls the voltage supply unit 200. In addition, the microcomputer 700 individually controls the microwave generation units 300 and 310.

  Also in the present embodiment, the microcomputer 700 performs the same microwave processing as in the flowcharts of FIGS. 4 and 5, but the frequency extraction processing is different from that of the first embodiment. In the second embodiment, frequency extraction processing performed by the microcomputer 700 will be described.

(2-2) Frequency Extraction Processing FIG. 8 is a diagram for explaining a specific example of the frequency extraction processing performed by the microcomputer 700 in the microwave oven 1 according to the second embodiment. FIG. 8 is a graph showing the change in the reflected power when the frequency of the microwave is swept. In FIG. 8, the vertical axis indicates the reflected power, and the horizontal axis indicates the frequency of the microwave.

  In the microwave oven 1 according to the present embodiment, microwaves are radiated from the two antennas A1 and A2. Therefore, in the following description, the reflected power on the antenna A1 side is referred to as first reflected power, and the reflected power on the antenna A2 side is referred to as second reflected power.

  In FIG. 8, the frequency characteristic of the first reflected power is indicated by a solid line, and the frequency characteristic of the second reflected power is indicated by a dotted line.

  Similar to the first embodiment, the frequency of the microwave radiated from each of the antennas A1 and A2 is individually swept before the main heating of the object. Thereby, the microcomputer 700 has the relationship between the first reflected power and the frequency when the first reflected power shows the minimum value, and the second reflected power when the second reflected power shows the minimum value. Stores the relationship with frequency.

  Note that the microcomputer 700 may store the relationship between the first and second reflected powers and the frequency in the entire frequency band when the microwave frequency is swept.

  By the frequency extraction process, the microcomputer 700 converts the frequency f1 when the first reflected power is minimum and the frequency h1 when the second reflected power is minimum into the first main heating frequency and the first heating frequency, respectively. Extracted as the main heating frequency of 2.

  Thereby, the microcomputer 700 controls the microwave generation unit 300 to radiate the microwave of the main heating frequency f1 from the antenna A1 with the second output power for the main heating of the object.

  Further, the microcomputer 700 controls the microwave generator 310 to radiate the microwave of the main heating frequency h1 from the antenna A2 with the second output power.

  When microwave radiation is performed by the plurality of antennas A1 and A2, the first and second reflected powers at the antennas A1 and A2 do not always match. As described above, by individually setting the frequencies of the microwaves radiated from the plurality of antennas A1 and A2, even when the microwave oven 1 has the plurality of antennas A1 and A2, the power conversion efficiency is sufficiently improved. The

  The microcomputer 700 performs the same process for the frequency re-extraction process.

(2-3) Other examples of frequency extraction processing (2-3-a)
In the second embodiment, the frequency extraction process may be performed as follows. As shown in FIG. 8, the frequency characteristics of the first and second reflected powers may each have a plurality of minimum values.

  At this time, for example, the microcomputer 700 extracts the frequencies f1, f2, and f3 corresponding to the plurality of minimum values for the first reflected power as the main heating frequency, and converts the frequencies of the second reflected power to the plurality of minimum values. Corresponding frequencies h1, h2, and h3 may be extracted as the main heating frequency.

  In this case, the microcomputer 700 sequentially switches the main heating frequencies f1, f2, and f3 of the microwaves radiated from the antenna A1, and sequentially switches the main heating frequencies h1, h2, and h3 of the microwaves radiated from the antenna A2. Also good.

  In this way, by performing the main heating at a plurality of frequencies corresponding to a plurality of minimum values, even when there are a plurality of minimum values at the same level during the sweep, the main heating of the object is performed with the microwaves of the respective minimum values. It can be carried out.

(2-3-b)
The microcomputer 700 is not limited to the above, and the microcomputer 700 has a set of adjacent frequencies f1, f1, f2, f3, h1, h2, h3 corresponding to a plurality of minimum values of the first and second reflected powers. h1, out of a set of frequencies f2 and h2 that are close to each other and a set of frequencies f3 and h3 that are close to each other, frequencies f1, f2, and f3 corresponding to smaller reflected power in each set are extracted as the main heating frequency. May be.

  In this case, the microcomputer 700 controls the microwaves radiated from the antennas A1 and A2 to the common frequencies f1, f2, and f3.

  When controlling the microwaves to a common frequency, instead of the two microwave generators 300 and 310, one microwave generator common to the antennas A1 and A2 is added to the microwave generator 100. Can be provided. Thereby, a structure becomes simple and size reduction is implement | achieved.

  Further, instead of the two microwave amplification units 400 and 410, one microwave amplification unit common to the antennas A1 and A2 can be provided in the microwave generator 100. Thereby, a structure becomes simple and size reduction is implement | achieved.

(2-3-c)
The microcomputer 700 is close to the average frequencies f1, h1, which are close to each other, with respect to the frequencies f1, f2, f3, h1, h2, h3 respectively corresponding to the plurality of minimum values of the first and second reflected powers. The average frequency of the frequencies f2 and h2 to be performed and the average frequency of the frequencies f3 and h3 adjacent to each other may be extracted as the main heating frequency.

[3] Correspondence between each constituent element of claim and each part of the embodiment Hereinafter, an example of correspondence between each constituent element of the claim and each part of the embodiment will be described, but the present invention is limited to the following example. Not.

  In the first and second embodiments, the microwave oven 1 and the microwave generation device 100 correspond to a microwave processing device, and the microwave generation units 300 and 310 and the microwave amplification units 400 and 410 are microwave generation means. Antennas A1 and A2 correspond to radiating portions, reflected power detection devices 600 and 610 correspond to detection means, microcomputer 700 corresponds to control means, and heat radiation fins 301 and 401 correspond to heat radiation means. The frequency re-extraction process corresponds to the frequency update process.

  INDUSTRIAL APPLICABILITY The present invention can be used for a processing apparatus that generates reflected power, such as a microwave oven, a plasma generation apparatus, a drying apparatus, and an apparatus that promotes an enzyme reaction.

The block diagram which shows the structure of the microwave oven which concerns on 1st Embodiment. The schematic side view of the microwave generator which comprises the microwave oven of FIG. The figure which showed typically the circuit structure of the microwave generator of FIG. The flowchart which shows the control procedure of the microcomputer of FIG. The flowchart which shows the control procedure of the microcomputer of FIG. The figure for demonstrating the specific example of the sweep of the frequency of a microwave, and frequency extraction processing The block diagram which shows the structure of the microwave oven which concerns on 2nd Embodiment. The figure for demonstrating the specific example of the frequency extraction process which a microcomputer performs in the microwave oven which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave oven 100 Microwave generator 300,310 Microwave generator 301,401 Radiation fin 400,410 Microwave amplifier 600,610 Reflected power detector 700 Microcomputer A1, A2 Antenna

Claims (12)

A microwave processing apparatus for processing an object using a microwave,
Microwave generation means for generating microwaves;
A radiating section for radiating the microwave generated by the microwave generating means to an object;
Detecting means for detecting reflected power from the radiating portion;
Control means for controlling the microwave generation means,
The control means causes the microwave to be emitted from the radiating unit to the object while changing the frequency of the microwave by the microwave generation means before processing the object, and the reflected power detected by the detection means is minimized. Alternatively, a microwave frequency for processing the object is determined as a processing frequency based on the minimum frequency, and the microwave having the determined processing frequency is generated by the microwave generation unit when the object is processed. The microwave processing apparatus characterized by the above-mentioned. 2. The micro of claim 1, wherein the control unit determines, as the processing frequency, one or a plurality of frequencies at which reflected power detected by the detection unit is minimized or minimized before processing the object. Wave processing device. The control means sets the power of the microwave radiated from the radiating unit to the target before processing the target to a value smaller than the power of the microwave radiated from the radiating unit to the target during processing of the target. The microwave processing apparatus according to claim 1, wherein the microwave processing apparatus is set. The microwave generation means includes a heat dissipation means,
The microwave power radiated from the radiating unit to the object before processing the object is set to a value lower than energy that can be radiated by the heat dissipating means. Wave processing device. The control means causes the microwave to be radiated from the radiating unit to the object while changing the frequency of the microwave by the microwave generation means during processing of the object, and the reflected power detected by the detection means is minimized. Alternatively, a frequency update process for determining a microwave frequency for processing an object as a new processing frequency based on a minimum frequency and generating a microwave having the determined new processing frequency by a microwave generation unit The microwave processing apparatus according to claim 1, wherein: The said control means performs the said frequency update process, when the reflected power detected by the said detection means exceeds the predetermined threshold value during the process of the target object, The said frequency update process is performed. Microwave processing device. The microwave processing apparatus according to claim 5 or 6, wherein the control means performs the frequency update processing every time a predetermined time elapses during processing of an object. The said control means changes the frequency of a microwave by the said microwave generation means in the fixed range containing the process frequency determined immediately before in the said frequency update process, The any one of Claims 5-7 characterized by the above-mentioned. The microwave processing apparatus as described in. A plurality of the radiation portions are provided,
The detection means detects reflected power from the plurality of radiation units,
The control means radiates microwaves from the plurality of radiating units to the object while changing the frequency of the microwaves by the microwave generating means before processing the object, and detects a plurality of detected by the detection means. 2. The microwave processing apparatus according to claim 1, wherein a microwave frequency for processing an object is determined as a processing frequency based on a frequency at which reflected power from the radiating unit is minimized or minimized. The treatment of the object is a heat treatment,
The microwave processing apparatus according to claim 1, further comprising a heating chamber that accommodates the object for heating. A microwave processing method for processing an object using a microwave,
Before processing the object, radiating the microwave from the radiating unit to the object while changing the frequency of the microwave and detecting the reflected power from the radiating unit;
Determining the frequency of the microwave for processing the object as the processing frequency based on the frequency at which the detected reflected power is minimized or minimized;
And a step of generating a microwave having a determined processing frequency when the object is processed. During processing of the object, radiating the microwave from the radiating unit to the object while changing the frequency of the microwave and detecting the reflected power from the radiating unit;
Determining the microwave frequency for processing the object as a new processing frequency based on the frequency at which the detected reflected power is minimized or minimized;
The microwave processing method according to claim 11, further comprising: generating a microwave of the determined new processing frequency.

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