JPH0817569A - High frequency heating device - Google Patents

Abstract

PURPOSE:To vary microwave impedance matching in a heating chamber to obtain an optimum heating condition by detecting the transition point of physical properties of a heating material during heating with the temperature of the heating material and operating a moving stub. CONSTITUTION:A microwave generated with a magnetron 10 is conducted to a wave guide 12 in which a moving stub 13 is arranged and radiated into a heating chamber 2. For example, in case of defrosting and reheating, infrared rays or radiant heat radiated from a heating material M on a turn table 3 in the heating chamber is measured with an infrared detecting device 60 or a thermistor, data on surface temperature is sent to a control circuit. In the control circuit, rotation position data of the moving stub 13, suitable to freezing state is read out according to the kind of the heating material, and the moving stub 13 is rotated to the suitable position by the control of a driving relay of a stub motor 15. Impedance matching between the magnetron 10 and the heating chamber 2 is made, and a microwave reflection electrical field is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating apparatus for heating an object to be heated with microwaves, and more particularly to a high frequency heating apparatus having a function of changing microwave impedance in a heating chamber.

[0002]

2. Description of the Related Art First, a first conventional example will be described. In the high-frequency heating device, the impedance of the heating chamber varies depending on factors such as the size of the object to be heated and the amount of water contained in the heating chamber, and depending on the type of object to be heated, a magnetron that is a microwave generation means. In some cases, impedance matching between the heating chamber and the heating chamber cannot be obtained, the microwave reflection electric field becomes large, and heating loss may increase. Therefore, there has been proposed a high-frequency heating device having a function of reducing the microwave reflection electric field by providing a means for impedance matching depending on the type of object to be heated.

FIG. 32 is a block diagram of a conventional high-frequency heating apparatus having such impedance matching means. This high-frequency heating device has a heating chamber 2 inside an outer casing 1.
A turntable 3 on which an object to be heated M is placed is rotatably supported by a center shaft 4 on the inner bottom surface of the heating chamber 2. The center shaft 4 is rotationally driven by a turntable motor 5, and at the same time, the lower end portion of the center shaft 4 is brought into contact with a capacitance type weight sensor 6 for measuring the weight of the object to be heated M.

Further, a magnetron 10 as a microwave generating means is arranged adjacent to the heating chamber 2 in the outer casing 1. The microwave generated by the magnetron 10 is radiated to the outside by the magnetron antenna 11,
It is guided to the waveguide 12 and radiated into the heating chamber 2. An opening cover 7 is attached to the joint between the heating chamber 2 and the waveguide 12 so that the inside of the waveguide 12 cannot be seen from the heating chamber 2 side.

In the waveguide 12, a metal reflector for impedance matching (hereinafter referred to as a movable stub) 13 is installed. As shown in the enlarged view of FIG. 33 and the perspective view of FIG. 34, the movable stub 13 is formed by bending a disc-shaped metal surface 13a made of a non-magnetic metal plate such as aluminum and the peripheral end thereof. It is composed of a metal stub 13b and is fixed to a rotary shaft 14 made of a low dielectric constant dielectric material such as plastic or ceramic.

The rotating shaft 14 is rotationally driven by a synchronous motor (hereinafter referred to as a stub motor) 15 whose rotation direction is restricted to one direction. A cam 16 for detecting a rotation reference position is attached to the rotary shaft 14, and a detection switch 17 having a micro switch driven by a protrusion provided on the cam 16 is arranged on an outer peripheral portion of the cam 16 to form a cam. The position of 16, that is, the position of the movable stub 13 can be detected. FIG. 35 is a diagram for explaining the rotational position of the movable stub 13, and the reference position 0
It shows the positions 0 to 15 which are divided into 16 equal parts in the counterclockwise direction.

When the microwave is radiated from the antenna 11, the microwave passes through the waveguide 12 as a traveling wave,
The object to be heated M radiated from the opening cover 7 into the heating chamber 2
Is absorbed by If the movable stub 13 is not installed, a part of the microwaves returns to the inside of the waveguide 12 as a reflected wave depending on the state of the object to be heated M, and is guided by the ratio of the reflected wave and the traveling wave or the phase state. The standing wave mode in the wave tube 12 changes, affecting the operating efficiency of the magnetron 10.

Therefore, in this high-frequency heating apparatus, the movable stub 13 installed in the waveguide 12 is rotated according to the object M to be heated so that the impedance is adjusted and the operating efficiency of the magnetron 10 is increased. ing. That is, when the metal stub 13b of the movable stub 13 reaches the reference position 0 by the rotation of the stub motor 15, the protrusion provided on the cam 16 drives the detection switch 17. As a result, the detection switch 17 sends an ON / OFF signal to the control circuit 20. Upon receiving this signal, the control circuit 20 reads the rotational position data of the movable stub 13 corresponding to the object to be heated M from the internal memory, controls the energization time of the stub motor 15 and stops the movable stub 13 at a predetermined position. Control to do. By changing the movable stub 13 according to the object to be heated M in this way, the heating efficiency for the object to be heated M is always increased regardless of the type of the object to be heated M.

Next, the second conventional example will be described. In the conventional high-frequency heating device, the height and weight of the object to be heated are measured, the object to be heated is compared and classified into pre-groups based on the measurement results, and the position preset for each group is set. There is a high-frequency heating apparatus having a function of obtaining optimum heating characteristics for an object to be heated by rotating the movable stub 13 described above.

In this high-frequency heating apparatus, the turntable 3 is rotated once so that the height of the object to be heated can be accurately measured regardless of the position of the object to be heated on the turntable 3. Taking the maximum value as the height of the heated object, the turntable 3 is rotated once for the purpose of canceling the unbalanced load even if the heated object is placed at any position on the turntable 3 in terms of weight. During that time, the weight of the object to be heated is calculated by averaging the weights measured at regular time intervals. The comparative classification of the objects to be heated into the pre-sorted groups is performed after one turn of the turntable 3, and then the movable stubs 13 are moved to the preset positions for each group.

Therefore, it is best to supply the electric power to the magnetron 10 after these measuring operations are completed from the viewpoint of heating efficiency, but the measurement, classification, and movable stub 13 of the object to be heated are performed. Since the time required for a series of operations such as movement is long, it takes time from the start of heating (start of measurement) to the end of heating, and the merit of shortening the heating time is lost. Therefore, during the period from the start of heating (start of measurement) to the end of measurement of the object to be heated and the operation of the movable stub 13, the voltage standing wave ratio (VS) is set for any load set in advance before heating. The movable stub 13 is located at a low position, and the magnetron 10 is operated and heated even while the object to be heated is measured.

Next, a third conventional example will be described. When thawing raw food such as sashimi frozen by a high-frequency heating device, if the temperature of the heated object after heating exceeds 0 ° C., the freshness of the food decreases and the taste becomes bad. Also, when raw food is heated with a high-frequency heating device, the temperature rises sharply, causing uneven heating, and when trying to keep the temperature of the object to be heated below 0 ° C, unthawed parts are created, and conversely unthawed parts If you try to get rid of, the overheated part will be created and it will be like a boiled state. Therefore, when thawing raw food, the power supply to the magnetron 10 is intermittently supplied, and the temperature of the heated object partially increased when the power is supplied to the magnetron 10 is dispersed when the power is not supplied to generate high frequency waves per unit time. The output is suppressed to improve the uniform heating characteristics.

However, when the high frequency output is suppressed by intermittent output, the temperature of the object to be heated, which has poor heat conduction characteristics, rises sharply due to the power supply from the magnetron 10, and the heat dispersion is insufficient when the power is not supplied. Therefore, a temperature difference may be created in the object to be heated. Further, if the power supply time to the magnetron 10 in the unit cycle during intermittent heating is shortened, it is necessary to secure the power supply time to the magnetron 10 in the unit cycle to some extent in order to extremely shorten the life of the magnetron 10. As a result, the higher the high-frequency heating device with the higher high-frequency output, the worse the uniform heating property during intermittent heating.

Therefore, recently, a weak power output is maintained without interrupting the power supply to the magnetron 10 by using an inverter power supply device capable of controlling the power supply amount to the magnetron 10 as a power supply source to the magnetron 10. A high-frequency heating device having such a structure has been proposed. FIG. 36 is a block diagram showing an inverter power supply device 30 of such a high frequency heating device. This device 30 is a rectifying / smoothing circuit 31 for rectifying and smoothing a commercial power source to obtain a DC power source, a transformer 32 for driving a magnetron, a resonance capacitor 33 connected in parallel to a primary winding 32a of the transformer 32, and a semiconductor switching circuit. 34, the ON / OFF pulse signal for high-frequency switching the semiconductor switching circuit 34 is changed to limit the amount of electric power supplied to the magnetron 10.

The secondary side of the transformer 32 has a secondary winding 32b.
A high-voltage capacitor 35 and a high-voltage diode 36 are connected to each other to form a voltage doubler circuit VM, which is connected to the magnetron 10 as a magnetron drive circuit. The cathode of the magnetron 10 is the capacitor 35 and the secondary winding 32b.
The inverter control circuit 40 is connected to the semiconductor control circuit 40 via the drive circuit 41, and a pulse signal is sent from the inverter control circuit 40 to the semiconductor switching circuit 34 via the drive circuit 41 to perform optimum control by feedback.

That is, the inverter control circuit 40 controls the output according to the magnetron output setting signal from the control circuit 20 for controlling the entire system, and controls the output based on the detection result of the input / output voltage / current. It is configured to adjust the drive pulse width and drive timing of the switching circuit 34. When thawing a raw product using such an inverter power supply device 30, it is possible to reduce the amount of power supplied to the magnetron 10 and realize a weak power output without interrupting the power supply to the magnetron 10. .

Next, a fourth conventional example will be described. Among high-frequency heating devices, there is a high-frequency heating device having a function of early detecting the modding (abnormal oscillation) of the magnetron 10 and returning the oscillation state of the magnetron 10 to normal operation. That is, in the block diagram of FIG. 36 described above, the resistor 37 connected to the terminal on the side of the inverter control circuit 40 of the secondary winding 32b of the transformer 32 is a magnetron anode current detection resistor, and the voltage across the resistor 37 is Is input to the control circuit 40.

A heater winding 32c for warming the filament of the magnetron 10 is connected to the magnetron anode, and the anode voltage of the magnetron 10 is controlled by a signal from the control circuit 20. In addition, the control winding 32d on the temporary side of the transformer 32 is input to the control circuit 40 for synchronization and output voltage detection. Further, a detection winding 32e for detecting the oscillation state of the magnetron 10 is provided on the secondary side of the transformer 32, and the driving of the control circuit 20 is stopped when the magnetron 10 is moded based on the output result from the detection winding 32e. A detection winding output shaping circuit 50 that transmits a reset pulse as a stop signal is provided. The output shaping circuit 50 and the control circuit 20 constitute drive stop means.

The transformer 32 for driving the magnetron is shown in FIG.
As shown in FIG. 7 and FIG. 38 (a cross-sectional view taken along the line AA in FIG. 37), the secondary winding 32b is wound around the region of the bobbin 32B divided into a plurality of stages on the core 32A having a square cross section. There is. The detection winding 32e is arranged in parallel with the secondary winding 32b in a region on the secondary side of the bobbin 32B as shown in FIG. 38, and differentially extracts the output fluctuation of the cathode voltage of the magnetron 10. One side of the detection winding 32e is connected to the output shaping circuit 50.

The detection winding output shaping circuit 50 includes the detection winding 3
The threshold voltage V _N with the voltage V _A from 2e as a reference value
A comparing circuit 51 for comparing with, a judging circuit 52 for judging that the magnetron 10 is in the moding state and outputting a trigger signal if the peak value of the voltage V _A is larger than the peak value of the threshold voltage V _N ; Of the pulse generation circuit 53 that transmits a stop signal (reset pulse) to the inverter control circuit 40 due to the arrival of the signal, and a reset as a drive recovery means that transmits the stop signal in the pulse generation circuit 53 for a certain period during moding and then prohibits the transmission. And a circuit 54.

The control circuit 20 is connected to the main control device and outputs a magnetron output setting signal to the inverter control circuit 40.
The switching element 34 is connected to the determination circuit 52 of the detection winding output shaping circuit 50, and the magnetron 10 oscillates at the output given by the output setting signal in synchronization with the signal from the control winding 32d. Drive control is performed via the drive circuit 41.

When the stop signal is not supplied to the inverter control circuit 40, the switching element 3 is supplied as the magnetron output setting signal is supplied from the control circuit 20.
4 is driven, and when the magnetron output setting signal is interrupted or when the stop signal is supplied from the output shaping circuit 50, the driving of the switching element 34 is stopped. In this way, the output shaping circuit 50 detects the modding of the magnetron at an early stage and stops the driving of the switching element 34 to restore the oscillation state of the magnetron 10 to the normal operation.

Next, a fifth conventional example will be described. When microwave heating is performed with a high-frequency heating device, in order to reduce heating unevenness, a method of rotating an object to be heated by a turntable to equalize microwave irradiation is adopted. However, the rotation of the turntable is flat, so there is little improvement effect on uneven heating in the vertical direction, and the portion located at the center of rotation does not move in the plane direction either, so that the turntable is rotated uniformly. The heating characteristics cannot be improved. Therefore, it is important to determine the opening position of the waveguide 12 to the heating chamber 2.

Generally, when the opening position of the waveguide 12 to the heating chamber 2 is at a relatively high position, any part of the object to be heated is wide with respect to the object to be heated which is wide in the plane direction and has no height. Since there is no great difference in the distance from the opening to the object to be heated, it has excellent uniform characteristics. However, for objects that are high in the vertical direction,
A large difference occurs in the distance from the opening to the upper part of the object to be heated, and the microwave concentrates on the upper part of the object to be heated, resulting in poor uniformity.

On the other hand, when the opening position of the waveguide 12 to the heating chamber 2 is at a relatively low position, the outer periphery of the object to be heated is wide with respect to the object to be heated which is wide in the plane direction and has no height. Since it is extremely close to the opening, microwaves concentrate only on that portion and the outer circumference is overheated, resulting in poor uniformity. But,
With respect to the object to be heated which is high in the vertical direction, there is no great difference in the distance from the opening to any part of the object to be heated, so that the uniform characteristics are excellent.

Next, a sixth conventional example will be described. Among conventional high-frequency heating devices, there is a high-frequency heating device having a function of detecting the finish of an object to be heated and ending heating. In such a high-frequency heating device, a humidity sensor is used as a means for detecting the heating state of the object to be heated, and the humidity sensor captures the change in the amount of water vapor emitted from the object to be heated with the temperature rise of the object to be heated. I am trying to detect the state.

Next, a seventh conventional example will be described. Among conventional high-frequency heating devices is a high-frequency heating device that measures the weight of an object to be heated placed on a turntable and performs heating control suitable for the weight of the object to be heated. One of the means for measuring the weight of an object to be heated is a method using a piezoelectric weight sensor. This method supports the turntable and rotates 3
The detection signal of the piezoelectric weight sensor provided at the roller passage point of the fork-shaped support roller base is input to the control circuit, and the peak hold circuit holds the peak voltage signal at a level exceeding the threshold voltage level for a certain period of time. The D converter reads the voltage level and sends the data to the arithmetic circuit.

When the object to be heated is placed in the center of the turntable, the weight of the object to be heated is about 1 on the three rollers.
Since the load of / 3 is applied, the output peak hold value corresponding to each roller of the weight sensor becomes substantially the same value. 3 if the object to be heated is placed around the turntable
Different loads are applied to the individual rollers depending on the position of the object to be heated, and the output peak hold values corresponding to the respective rollers of the weight sensor have different values.

[0029]

In the first conventional example described above, the movable stub 13 is moved to a position suitable for a preselected menu, and is heated by impedance matching according to the object to be heated. Also, for example, when the physical properties of the object to be heated change during microwave heating, such as when thawing frozen food from the frozen state and then warming and heating after thawing, the impedance in the heating chamber 2 is 0 ° C. Since the melting point is different between the following state and the state of 0 ° C. or more, there is a disadvantage that impedance matching is deviated at the time of leaving the frozen state and heating loss increases.

Next, in the above-mentioned second conventional example, the previously classified groups in the shape determination of the object to be heated are:
Although it covers the load capacity that will be used, the container to put the heated object is different for each user, and if the weight and height are extremely different from the average container, the weight of the heated object and the container Since it is impossible to measure the height and the height separately, there is the inconvenience that some containers are classified into different groups from the intended group.

Further, in the above-mentioned second conventional example, the movable stub 13 is positioned at a position where the voltage standing wave ratio is low with respect to any load preset before heating, and microwave heating is continued. After recognizing the shape of the object to be heated, the movable stub 13 is rotated to the position of the microwave impedance having the optimum heating characteristic for the object to be heated. If present, discharge may occur in the waveguide 12 when the movable stub 13 passes through that position, and in the worst case, the magnetron 10 may be destroyed.

Next, in the above-mentioned third conventional example, when the transformer 32 for driving the magnetron constituting the inverter power supply device 30 is composed of the primary winding 32a, the secondary winding 32b and the heater winding 32c. As is clear from the "magnetron input power-filament current characteristic" shown in FIG. 39, the filament current may decrease as the input power to the magnetron 10 decreases, and the filament temperature may decrease to cause moding.

On the other hand, if the temperature of the filament exceeds a certain value, the life of the magnetron 10 becomes extremely short, so the upper limit of the filament current is inevitably determined. Therefore, in the inverter power supply device 30 having the magnetron driving transformer 32 having the above-described configuration, when the power supplied to the magnetron 10 becomes less than a certain amount, the filament current becomes insufficient, so that a high frequency output such as the defrosting of a raw product is generated. When it is necessary to suppress the power consumption to a considerably low level, it is necessary to change the pulse signal for switching the semiconductor switching circuit 34 at a high frequency to reduce the power supplied to the magnetron 10 and to interrupt the power supply to the magnetron 10. is there.

However, when the power supply to the magnetron 10 is reduced and the power supply to the magnetron 10 is interrupted at the same time, the uniform heating characteristic is that when the power supplied to the magnetron 10 is reduced and the power supply to the magnetron 10 is interrupted. This is inferior to the case where a high frequency output equivalent to the apparent high frequency output is realized by continuous heating only by reducing the input power of the inverter circuit 30 to the magnetron 10.

On the other hand, in order to realize a state in which the high-frequency output is suppressed to a considerably low level, such as thawing raw food, by continuous heating only by changing the pulse signal for high-frequency switching the semiconductor switching circuit 34 of the inverter circuit 30, a transformer is used. It is necessary to separate the heater winding 32c from 32 and separately provide a transformer for heating the filament, which is costly and disadvantageous in that the installation space for other components is greatly restricted.

Next, in the above-mentioned fourth conventional example, the method of detecting the modding of the magnetron 10 can only stop the continuous modding after the occurrence of the modding of the magnetron 10, and until it is detected. Damage to the magnetron 10 due to the modding during the period cannot be avoided. Further, the frequency of occurrence of modding increases with the period of use of the magnetron 10, and rapidly increases as the end of the magnetron 10's life approaches. Therefore, when frequent moding occurs in one heating cycle, pulse generation occurs. After the stop signal in the circuit 53 is transmitted for a certain period of time, the non-oscillation period of the magnetron 10 is significantly increased by the drive recovery means that inhibits the transmission and restores the drive of the switching circuit 34, and the high frequency output per unit time is increased. It will be greatly reduced.

Further, the moding detecting means is limited to the high frequency heating device having the inverter power supply device 30, and it is necessary that the transformer 32 further has the moding detecting winding 32e. Further, as described in the third conventional example, the pre-classified group for determining the shape of the object to be heated covers the load capacity that will be used, but it depends on the container on which the object to be heated is placed. In rare cases, the impedance matching may be prone to cause moding, and in order to avoid this, the microwave impedance matching may be set off from the best position in the normal state.

Next, in the above-mentioned fifth conventional example, the opening position of the waveguide to the heating chamber, which has excellent uniform heating characteristics on both the plane and the upper and lower sides, is determined by It is often located between the opening position which is excellent in uniform heating characteristics, and in many cases, it is a position in which uniform heating characteristics are compromised, rather than being excellent in both. For this reason, the object to be heated that is extremely large in the plane direction and has no height, or the object to be heated, which is the opposite, may not have a sufficiently uniform heating characteristic. Particularly, in recent years, it has been desired to shorten the heating time, and a high-frequency heating device having a high high-frequency output has been proposed, but the uniform heating characteristic deteriorates as the high-frequency output increases.

Next, in the sixth conventional example described above, when the heating state of the object to be heated is detected using the humidity sensor,
When a thin film for food packaging (hereinafter referred to as "wrap") is used to warm and heat an object to be heated, the steam that covers the object to be heated and emits steam from the object to be heated is between the saucer and the wrap of the object to be heated. When the object to be heated is steamed and heated by enclosing it in a space that can be opened, the detection time will vary due to how the water vapor leaks due to the sealed state of the wrap. ,
There may be variations in the finish.

Next, in the above-mentioned seventh conventional example, when the position of the object to be heated placed on the turntable is recognized by the piezoelectric type weight sensor, it is placed at the center or on the outer periphery. It is a binary choice, and it is not possible to make the ultimate choice as to whether or not it is located near the outermost circumference. Further, when a plurality of objects having the same weight are placed on the outer circumference at equal intervals, it is determined that the objects are placed in the center of the turntable.

When the object to be heated is placed on the outermost circumference of the turntable, as is apparent from the Smith chart shown in FIG. 40, the microwave impedance in the heating chamber changes greatly in synchronization with the rotation of the turntable. Especially when the object to be heated passes near the opening that radiates microwaves, when the object to be heated is located in front of the opening (a on the Smith chart
Point), the microwave impedance may shift greatly and enter the moding region, and the magnetron may cause moding.

Further, even if the object to be heated is near the outer circumference of the turntable and the height of the object to be heated is low and the opening for radiating microwaves is small, the microwave impedance in the heating chamber is greatly affected. There is a case that it does not enter the moding area. However, in this case as well, the movable stub is moved to a position avoiding moding regardless of the height of the object to be heated, and therefore ideal microwave impedance matching is performed by unnecessary moding avoiding operation. The microwave impedance deviates from the position of, and heating is performed, and the heating efficiency decreases.

Further, as shown in the Smith chart of FIG. 41, when the position of the movable stub is determined so as not to cause moding when the object to be heated passes in front of the opening radiating the microwave, When there is a position of the object to be heated other than the vicinity, impedance matching may not be efficiently absorbed by the object to be heated.

As described above, the conventional high-frequency heating device has various disadvantages to be solved. The first object of the present invention is to
An object of the present invention is to provide a high-frequency heating device capable of creating an optimum heating state by changing the microwave impedance matching in the heating chamber even when the physical properties of the object to be heated change during microwave heating.

A second object of the present invention is to guide a metal reflector (movable stub) which is moved during microwave heating even if there is a position where the voltage standing wave ratio becomes high during the movement. It is an object of the present invention to provide a high-frequency heating device capable of preventing a discharge from occurring in a wave tube and a magnetron from being destroyed.

A third object of the present invention is to provide a high-frequency heating device capable of improving uniform heating characteristics by continuously heating at a low output as in the case of thawing raw food.

A fourth object of the present invention is to provide a high frequency heating device capable of preventing abnormal oscillation of the magnetron.

A fifth object of the present invention is to provide a high-frequency heating device which is excellent in uniform heating characteristics for an object having a certain shape.

A sixth object of the present invention is to provide a high-frequency heating device capable of accurately detecting the finish of the object to be heated when the object to be heated is covered with wrap and steamed for heating.

A seventh object of the present invention is to prevent an abnormal oscillation of the magnetron which occurs when the object to be heated passes near the opening of the waveguide when the object to be heated is placed near the outermost circumference of the turntable. An object of the present invention is to provide a high-frequency heating device that can be prevented.

[0051]

According to the first aspect of the present invention,
Microwave generating means, a waveguide for guiding microwaves radiated from the microwave generating means to the heating chamber, a dielectric rotating shaft inserted in the waveguide, and a metal surface supported by the dielectric rotating shaft. And a metal reflector for impedance matching, which comprises a metal stub provided on the periphery of the metal surface,
In a high frequency heating device having a control means for controlling the rotation of the metal reflector, there is a means for discriminating a change point at which the physical properties of the object to be heated change during microwave heating depending on the temperature of the object to be heated. The microwave reflector is operated before and after to change the microwave impedance matching in the heating chamber to create an optimum heating state in each physical state of the object to be heated.

According to a second aspect of the present invention, microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to the heating chamber, and a dielectric rotating shaft inserted in the waveguide. A high-frequency heating device including a metal reflector for impedance matching having a metal surface supported by a dielectric rotating shaft and a metal stub provided on a peripheral portion of the metal surface, and a control means for controlling rotation of the metal reflector. , When the metal reflector rotates and passes through the position where the voltage standing wave ratio increases during microwave heating, the power supply to the microwave generation means is temporarily stopped or lowered to thereby It is configured to prevent discharge.

According to a third aspect of the present invention, microwave generating means, a waveguide for guiding the microwave radiated from the microwave generating means to the heating chamber, and a dielectric rotating shaft inserted in the waveguide. A high-frequency heating device including a metal reflector for impedance matching having a metal surface supported by a dielectric rotating shaft and a metal stub provided on a peripheral portion of the metal surface, and a control means for controlling rotation of the metal reflector. By rotating the metal reflector to create a state in which microwaves are less likely to hit the object to be heated, the microwave generator is continuously supplied without interruption to perform continuous operation at low power, and the microwave is not frozen. The heating material is configured to be thawed by uniform heating.

According to a fourth aspect of the present invention, there is provided microwave generating means, a waveguide for guiding the microwave radiated from the microwave generating means to the heating chamber, and a dielectric rotating shaft inserted in the waveguide. A high-frequency heating device including a metal reflector for impedance matching having a metal surface supported by a dielectric rotating shaft and a metal stub provided on a peripheral portion of the metal surface, and a control means for controlling rotation of the metal reflector. A detection means for detecting the oscillation state of the microwave generation means is provided, and when the detection means detects an oscillation abnormality of the microwave generation means, the control means rotates the metal reflector to change the microwave impedance matching in the heating chamber. As a result, the abnormal oscillation of the microwave generation means is stopped.

According to a fifth aspect of the present invention, there is provided microwave generating means, a waveguide for guiding the microwave radiated from the microwave generating means to the heating chamber, and a dielectric rotating shaft inserted in the waveguide. A high-frequency heating device including a metal reflector for impedance matching having a metal surface supported by a dielectric rotating shaft and a metal stub provided on a peripheral portion of the metal surface, and a control means for controlling rotation of the metal reflector. And a storage means for storing the state of the object to be heated and the position of the metal reflector when the microwave generating means causes an oscillation abnormality, and the control means stores the memory means when the object to be heated in the same state is heated again. It is configured to move the position of the metal reflector to the position avoiding the oscillation abnormality from the data stored in.

According to a sixth aspect of the present invention, microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to the heating chamber, a dielectric rotating shaft inserted in the waveguide, In a high-frequency heating device comprising a metal surface supported by a dielectric rotating shaft and a metal reflector for impedance matching having a metal stub provided in the peripheral portion of this metal surface, and a control means for controlling the rotation of the metal reflector, Having a temperature detecting means on the outer surface of the microwave generating means,
The temperature detecting means measures the temperature change per unit time of the microwave generating means, and the control means rotates the metal reflector according to the temperature change to change the microwave impedance matching in the heating chamber.

According to a seventh aspect of the present invention, the first and second microwave generating means and the first and second microwave guiding means for radiating the microwaves radiated from the first and second microwave generating means to the heating chamber. A high frequency heating apparatus including a waveguide, a means for measuring the shape of an object to be heated housed in a heating chamber, and a control means for controlling electric power supplied to the first and second microwave generation means. And the first waveguide has an opening at a position excellent in uniform heating property of the object to be heated, and the second waveguide has an opening at a position excellent in uniform heating property of the object to be heated. And the control means is configured to control the power supply to the first and second microwave generation means in accordance with the shape of the object to be heated.

According to an eighth aspect of the present invention, in the high-frequency heating apparatus according to the seventh aspect, the control means is heating the power supply to the first and second microwave generation means in accordance with the shape of the object to be heated. It is configured to switch to.

According to a ninth aspect of the present invention, microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to the heating chamber, and a dielectric rotating shaft inserted in the waveguide. A high-frequency heating device including a metal reflector for impedance matching having a metal surface supported by a dielectric rotating shaft and a metal stub provided on a peripheral portion of the metal surface, and a control means for controlling rotation of the metal reflector. , Having height measuring means for measuring the height of the object to be heated,
The height of the object to be heated is periodically measured by the height measuring means during microwave heating, and expansion during heating of the thin film for food packaging for heating the object by covering the object to be heated is performed. It is configured to detect the finish of the object to be heated.

According to a tenth aspect of the present invention, microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to the heating chamber, a dielectric rotating shaft inserted in the waveguide, In a high-frequency heating device comprising a metal surface supported by a dielectric rotating shaft and a metal reflector for impedance matching having a metal stub provided in the peripheral portion of this metal surface, and a control means for controlling the rotation of the metal reflector, The control means has a sensor means for recognizing a state where the object to be heated in the heating chamber is placed on the turntable, and when the sensor means recognizes that the object to be heated is located in the vicinity of the outermost circumference on the turntable, the control means The position of the metal reflector is controlled by adjusting the timing when the object to be heated passes in front of the opening of the waveguide that radiates microwaves to prevent abnormal oscillation of the microwave generation means. Configured to avoid.

[0061]

The high-frequency heating device according to the invention of claim 1
In the menu where the physical properties of the object to be heated change, especially in the menu such as frozen food where the melting point is passed from the frozen state and further thawing and reheating is performed by further heating, the infrared or radiant heat emitted from the object to be heated is heated in the heating chamber. The surface temperature of the object to be heated is detected by non-contact measurement with an infrared sensor or a thermistor provided in, and the impedance matching of the object to be heated when the surface temperature of the object to be heated exceeds 0 ° C is above the melting point. A highly efficient high-frequency heating device is realized by rotating the movable stub to a position where it can be taken.

In the high-frequency heating apparatus according to the second aspect of the present invention, the power supply to the magnetron is stopped only when the metal reflector (movable stub) passes the position where VS (voltage standing wave ratio) becomes high. Or, by limiting the amount of power supplied to the magnetron and suppressing the radio waves generated by the magnetron below the energy required for discharge in the waveguide, it is highly efficient and shortens the heating time from the start of measurement.
Allows safe operation without discharge.

In the high-frequency heating apparatus according to the third aspect of the present invention, when cooking such as thawing frozen foods by setting the high-frequency output to a low level, the high-frequency heating apparatus is installed in the waveguide for the purpose of changing the microwave impedance matching in the heating chamber. The movable stub provided is moved to a position where microwave reflection is large with respect to the magnetron. When the magnetron is oscillated in this state, the radio waves emitted from the magnetron are not efficiently irradiated to the object to be heated but are reflected and return to the magnetron to heat the magnetron itself.

On the other hand, the magnetron has a conversion efficiency of about 70% of the input power even in the normal impedance matching, and the remaining 30% becomes heat to heat the magnetron main body, and has a sufficient cooling structure. Even if the magnetron is oscillated in a state where there are many reflections, it has the ability to sufficiently dissipate the calorific value of the magnetron itself when the input power is reduced in advance, so there is no risk of damaging the magnetron.

In this microwave impedance matching state, since the heating efficiency of the object to be heated is poor, a large amount of magnetron input power is required to obtain the required high frequency output, and as a result, the primary winding is increased without increasing the high frequency output. It is possible to increase only the filament current generated by the magnetron driving transformer configured by the secondary winding and the filament heating winding (heater winding).

In the high-frequency heating apparatus according to the fourth aspect of the present invention, microwave impedance matching in the heating chamber, which is the main cause of the modding of the magnetron, is rotated before the occurrence of the modding by rotating the movable stub. Since it changes, the occurrence of moding can be improved from the cause.

According to a fifth aspect of the present invention, in the high-frequency heating apparatus, the shape data of the object to be heated obtained from the shape recognition data of the object to be heated is stored together with the amount of movement of the movable stub after detecting the moding. If the object to be heated that is the same as the shape data is heated again, the moving stub will be corrected and moved to the previously moved position so as not to cause the moding at the same time as the heating. With respect to the load that caused the, the moding is never caused again in the subsequent heating.

In the high-frequency heating apparatus according to the sixth aspect of the present invention, the control circuit directly detects the microwave radiation state to the object to be heated by detecting the heating efficiency of the microwave to the object to be heated by the temperature change of the magnetron. The movable stub can be sensed and actuated to improve microwave impedance matching. In particular, as a means of detecting the modding of the magnetron, paying attention to the rapid temperature rise due to the modding of the magnetron, the moding is detected by the temperature change of the magnetron, and the microwave impedance matching in the heating chamber, which is the main cause of the occurrence of the modding, is detected. By moving the movable stub, it is changed from the state before the occurrence of moding and the moding is stopped.

In the high-frequency heating apparatus according to the seventh and eighth aspects of the present invention, the microwave feeding opening to the object to be heated is selected according to the shape of the object to be heated, or the microwave is applied to the object to be heated during heating. By switching the magnetron that supplies power to the aperture that radiates waves, or with a different aperture 2
The uniform heating characteristics of the object to be heated are improved by controlling the amount of power supplied to each of the two magnetrons.

According to the ninth aspect of the present invention, in the high-frequency heating apparatus, the height measuring means for detecting the height of the heated object is used to measure the bulge of the wrap expanded by the pressure of the steam generated from the heated object. Since the detection is performed and the automatic cooking is ended by using it as a means for detecting the finish of the object to be heated, the finish of the object to be heated can be accurately detected.

According to a tenth aspect of the present invention, there is provided a high frequency heating apparatus, comprising: a plurality of light emitting elements provided on a wall surface of a heating chamber;
The turntable detects the output voltage difference of the light receiving element depending on whether or not the object to be heated that crosses the same number of light receiving elements similarly installed on the opposite wall surface by the rotation operation of the turntable blocks the light of the light emitting element. It has a function of recognizing the placed state of the object to be heated.

When it is recognized that the object to be heated on the turntable is located in the vicinity of the outermost circumference, the position of the movable stub is corrected to avoid the moding. Further, the output of the inverter circuit is suppressed and the modding is avoided at a timing when the object to be heated placed deviating from the position of the turntable passes in front of the opening radiating the microwave.

[0073]

First, a first embodiment of the high-frequency heating apparatus according to the present invention will be described. The present embodiment corresponds to the invention described in claim 1. FIG. 1 is a block diagram showing a first embodiment of a high-frequency heating apparatus according to the present invention, in which the same components as those in the above-mentioned conventional example are designated by the same reference numerals. The high-frequency heating apparatus according to the present embodiment has the configuration shown in FIG. 32 described above, in which the article to be heated M placed on the turntable 3 is heated.
The infrared sensing device 60 is arranged on the top surface or the side surface of the heating chamber 2 through which the surface of the heating chamber 2 can be seen. This infrared sensing device 60, as shown in FIG.
The infrared ray radiated from the sensor 61 is detected by the sensor 61, and the surface temperature of the object to be heated M is measured by comparing with the temperature of the chopper 63 that crosses the front of the sensor 61 periodically by the rotation of the chopper drive motor 62. Is transmitted to the control circuit 20 of the control device 70 described later.

The other structure is the same as the structure shown in FIG. Briefly, a magnetron 10 as microwave generating means is arranged adjacent to the heating chamber 2,
Microwaves generated in the magnetron 10 are radiated to the outside by the magnetron antenna 11, guided to the waveguide 12, and radiated into the heating chamber 2. A movable stub 13 is installed in the waveguide 12, and by setting the rotational position of the movable stub 13 in correspondence with the object M to be heated stored in the heating chamber 2, Heating chamber 2
And an impedance matching between them and to reduce the microwave reflected electric field. The structure of the movable stub 13 is the same as that shown in FIGS. 33 and 34.

FIG. 3 is a block diagram of the control device 70 in the high frequency heating apparatus of this embodiment. The control device 70 has a configuration in which a plurality of drive relays are connected in parallel to the input AC power supply AC. That is, the heating chamber 2
Lamp drive relay 7 that drives the lamp L that illuminates the inside
1. Cooling fan motor FM for cooling magnetron 10
Cooling fan drive relay 72 for driving the stub motor 1
Stub motor drive relay 73 for driving 5 and turntable drive relay 7 for driving turntable motor 5
4. Heating relay 75 for supplying power to magnetron 10
Are respectively connected in parallel to the input AC power supply AC.

The contacts of each of the relays 71 to 75 are ON / OFF driven by each drive transistor, and each drive transistor is controlled by a drive signal supplied from the control circuit 20 via the interface 21. The control circuit 20 is a control circuit having a microcomputer configuration.
In order to execute the control specified by the user on the operation panel 22, a pre-programmed program memory is incorporated. The control circuit 20 also includes an infrared sensing device 6
The surface temperature data of the object to be heated M measured at 0 is converted into a digital signal by the A / D converter 23 and input through the interface 21, and the on / off state of the detection switch 17 that is turned on by the rotation of the stub motor 15 Is input via the interface 21.

The output of the heating relay 75 is connected to the primary winding 32a of the transformer 32. Secondary winding 3 of transformer 32
2b is connected to a voltage doubler circuit VM composed of a high voltage capacitor 35 and a high voltage diode 36, and the midpoint of the connection is connected to the magnetron 10. A heater winding 32c for warming the filament of the magnetron 10 is connected to the magnetron anode on the secondary side of the transformer 32, and the anode voltage of the magnetron 10 is controlled by a signal from the control circuit 20.

Next, the operation of the high-frequency heating apparatus according to this embodiment having such a structure, particularly the impedance adjustment by controlling the rotational position of the movable stub 13, will be described. FIG. 4 is a diagram in which the impedance on the heating chamber 2 side when the object M to be heated is placed in the heating chamber 2 and the turntable 3 is rotated is plotted on a Smith chart. In the figure, a is the impedance of the heated object M in the frozen state, and b
Is the impedance of the heated object M after thawing, α is the locus of the impedance of the heated object M in the frozen state when the turntable 3 is stopped and the movable stub 13 is rotated, and β is the turntable 3 stopped 3 is a locus of impedance of the object to be heated M after being thawed when the movable stub 13 is rotated by the above. In the figure, the numbers added to the loci α and β indicate the rotational positions 0 to 15 (see FIG. 35) of the movable stub 13.

In the high frequency heating apparatus according to this embodiment, when the physical properties of the object to be heated M are thawed from a frozen state such as frozen foods during microwave heating, and then heating is further performed to shift to warming heating, Control circuit 20 after heating starts
Reads the rotational position data of the movable stub 13 suitable for the frozen object M according to the type of the object M from the internal memory, and controls the stub motor drive relay 73 to control the energization time of the stub motor 15. Then, the movable stub 13 is rotated to a position suitable for the object to be heated M in a frozen state. In the case of this example, the rotational position data of the movable stub 13 is the data of the point 4 (that is, the rotational position 4) of the locus α in FIG.

After the rotation of the movable stub 13 or in parallel with the rotation of the movable stub 13, the contact of the heating relay 75 is closed by the control signal of the control circuit 20 to supply the electric power to the magnetron 10 and operate the magnetron 10 to operate. The heating object M is radiated with microwaves to be heated. When the temperature of the object to be heated M reaches 0 ° C., the control circuit 20 detects the melting point of the object to be heated M from the temperature data from the infrared sensing device 60, and the movable type suitable for the object to be heated M after being defrosted from the internal memory. By reading the rotational position data of the stub 13 and controlling the stub motor drive relay 73, the energization time of the stub motor 15 is controlled to move the movable stub 13 to a position suitable for the object M to be heated after thawing. In the case of this example, the rotational position data of the movable stub 13 is the data of the point 9 (that is, the rotational position 9) of the locus β in FIG. During this period, the control circuit 20 supplies electric power to the magnetron 10 while keeping the contact of the heating relay 75 closed, and operates the magnetron 10 to continue heating the object M to be heated.

The means for measuring the surface temperature of the object to be heated M is not limited to the infrared sensing device 60, and as shown in FIG. 5, a bowl-shaped reflecting plate 6 for reflecting the radiant heat of the object to be heated M.
5, a radiant heat sensor 68 including a thermistor 66 that detects the reflected heat and a thermistor 67 that corrects the detected temperature
The same effect can be obtained by using.

As described above, according to this embodiment,
In a menu in which the physical properties of the object to be heated M change, particularly in a menu such as frozen shoumai that performs thawing and reheating to heat the material from the frozen state past the melting point, the infrared rays or radiant heat emitted from the object to be heated M is not contacted. The surface temperature of the object to be heated M is detected by measuring with M, and when the surface temperature of the object to be heated M exceeds 0 ° C., the object to be heated M having a melting point or higher.
Movable stub 13 to a position where impedance matching can be achieved
By rotating the, it is possible to realize a high-efficiency high-frequency heating device.

Next, the second embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. This embodiment is a movable stub 1
When rotating 3 to a position suitable for the object to be heated M to perform impedance adjustment, the height and weight of the object to be heated M are measured, and the position of the movable stub 13 is adjusted based on the measurement result. It corresponds to the invention of claim 2.

FIG. 6 shows a second example of the high-frequency heating apparatus according to the present invention.
FIG. 1 (a) is a vertical sectional view, FIG.
Is a horizontal sectional view. This device has a function of measuring the height of the object to be heated M, and a plurality of light emitting elements LD are provided on the wall surface of the heating chamber 2 at regular intervals in the vertical direction. The same number of light receiving elements PD are provided in the same height positional relationship. The light emitted from the light emitting element LD passes through the center of the turntable 3 or in the vicinity thereof and strikes the light receiving element PD, so that the light emitting element LD
And a light receiving element PD are arranged. In the high frequency heating apparatus of this embodiment, the waveguide 12 and the magnetron 10 are used.
Is located in the center of the right side wall of the heating chamber 2,
D is located at the rear of the right side wall of the heating chamber 2, and the light receiving element PD is arranged at the front of the left side wall of the heating chamber 2 on the line connecting the center of the turntable 3 and the light emitting element LD corresponding to the light emitting element LD. There is.

Further, this apparatus has a function of measuring the weight of the object to be heated M, and the weight sensor 6 is provided below the heating chamber 2. FIG. 7 is an enlarged view of the weight sensor 6. The weight sensor 6 includes a plate spring 6a and an oscillation substrate 6b that are horizontally installed at a certain distance from each other. The plate spring 6 has a center at which the upper end supports the turntable 3 and the lower end penetrates the bottom surface of the heating chamber 2. Support the lower end of the shaft 4 and turntable 3
It slides up and down depending on the weight added to it. Leaf spring 6a
Also serves as an electrode and constitutes a capacitor between the electrode and the electrode formed in a pattern on the oscillation substrate 6b, and when the weight of the object to be heated M pushes down the leaf spring 6a via the center shaft 4,
The structure is such that the distance between the leaf spring 6a and the pattern electrode on the oscillation substrate 6b is changed.

As a result, the capacitance of the variable capacitor composed of the leaf spring 6a and the pattern electrode on the oscillation substrate 6b is changed, and as a result, the oscillation frequency of the oscillation circuit in the oscillation substrate 6b is changed. The weight of the article to be heated M is measured. In the high-frequency heating device having the weight sensor 6 as described above, when the object M to be heated is placed on the turntable 3 with its center deviated, an error occurs in the measured weight due to friction at the sliding portion of the center shaft 4. . Therefore turntable 3
Is rotated once, and the average value of the weights measured at fixed time intervals is taken to cancel out the unbalanced load of the article to be heated M.

FIG. 8 is a block diagram of the control device 70 in this embodiment. This control device 70 is the same as the control device 70 shown in FIG. 3, except that the heating relay 75 is removed and, instead, a rectifying / smoothing circuit 31 for rectifying and smoothing a commercial power source to obtain a DC power source as a power source circuit for supplying power to the magnetron 10. A transformer 32 for driving the magnetron, a resonance capacitor 33 and a semiconductor switching circuit 34 connected in parallel to the primary winding 32a of the transformer 32, and changing an on / off pulse signal for high frequency switching of the semiconductor switching circuit 34. Let me magnetron 10
An inverter circuit is connected to limit the amount of power supplied to the inverter.

The secondary side of the transformer 32 has a secondary winding 32b.
A high-voltage capacitor 35 and a high-voltage diode 36 are connected to each other to form a voltage doubler circuit VM, which is connected to the magnetron 10 as a magnetron drive circuit. The cathode of the magnetron 10 is the capacitor 35 and the secondary winding 32b.
The inverter control circuit 40 is connected to the semiconductor control circuit 40 via the drive circuit 41, and a pulse signal is sent from the inverter control circuit 40 to the semiconductor switching circuit 34 via the drive circuit 41 to perform optimum control by feedback.

The resistor 37 connected to the terminal on the side of the inverter control circuit 40 of the secondary winding 32b of the transformer 32 is a magnetron anode current detection resistor, and the voltage across the resistor 37 is input to the control circuit 40. It Further, a heater winding 32c for heating the filament of the magnetron 10 is connected to the magnetron anode, and the anode voltage of the magnetron 10 is controlled by a signal from the control circuit 20. Further, the control winding 32d on the temporary side of the transformer 32 is input to the inverter control circuit 40 for synchronization and output voltage detection.

The control circuit 20 is connected to the operation panel 22, and further connected via the interface 21 to the inverter control circuit 40, the drive transistors of the relays 71 to 74, the detection switch 17, the weight sensor 6 and the light receiving element PD. There is.

Next, the operation of the high frequency heating apparatus according to this embodiment will be described. FIG. 9 is a diagram in which a change in impedance on the heating chamber 2 side when the movable stub 13 is rotated is plotted on a Smith chart. When the object M to be heated is placed on the turntable 3 and heating is started, the control circuit 20
Controls the turntable drive relay 74 to supply power to the turntable motor 5,
Is rotated to rotate the object to be heated M on the turntable 3, and each output level of the light receiving element PD is measured.

The purpose of rotating the object to be heated M during height measurement is to position the object to be heated M between the light emitting element LD and the light receiving element PD when the object M to be heated is eccentrically placed on the turntable 3. If the object M to be heated is positioned between the light emitting element LD and the light receiving element PD by rotating, assuming that the light of the light emitting element LD is not correctly blocked (the light emitting element LD and the light receiving element PD are connected to each other). This is to create a state in which the line, the object to be heated M, and the line connecting the centers of the turntables 3 overlap each other.

The control circuit 20 reads the output signal of the light receiving element PD while the turntable 3 rotates, and the light from the light emitting element LD is blocked during the rotation (the output level of the light receiving element PD becomes zero). The height to the uppermost light receiving element PD is determined as the height of the article to be heated M. At the same time as this height measurement, the above-mentioned weight measurement is performed.

During the height measurement and the weight measurement of the object to be heated M, the movable stub 13 is previously controlled by the control circuit 2 after the previous heating.
The stub motor drive relay 73 is controlled by 0 and remains stopped at a position where VS is low (position 0 in FIG. 9) for any position-determined load.

On the other hand, the control circuit 20 sends a control signal to the inverter control circuit 40 at the same time as the heating operation to supply electric power to the magnetron 10 to heat the object M to be heated by the microwave radiated from the magnetron 10. Then, the control circuit 20 calls the optimum microwave impedance matching position from the memory in the control circuit 20 from the height and weight of the object to be heated M measured after the turntable 3 makes one rotation, and controls the stub motor drive relay 73. Then, the stub motor 5 is rotated to move the movable stub 13 to the optimum impedance matching position 12 (FIG. 9).

At this time, since the movable stub 13 passes near the position 4 where VS is high while moving from the position 0 to the position 12, the control circuit 20 has a high VS from the measured height and weight of the object to be heated M. While inferring the position 4 and recognizing the rotational position of the movable stub 13 from the power supply time to the stub motor 15, the output control signal is sent to the inverter control circuit 40 when the movable stub 13 passes the position. The power supply to the magnetron 10 is stopped or the power supply to the magnetron 10 is suppressed to a level at which there is not enough energy for discharging, and the power supply to the magnetron 10 is reduced after the movable stub 13 has passed the high VS position. Control to return to the original level. This control is performed in the high-frequency heating device in which the movable stub 13 is continuously rotated during the heat radiation for the purpose of improving the uniform heating characteristic. Can be prevented.

As described above, according to this embodiment,
Only when the movable stub 13 passes a position where VS (voltage standing wave ratio) becomes high, the power supply to the magnetron 10 is stopped, or the power supply amount to the magnetron 10 is limited by an inverter circuit and guided. By suppressing the radio waves generated by the magnetron 10 in the tube 12 to be less than the energy required for discharge, it is possible to perform a highly efficient operation, shorten the heating time from the start of measurement, and perform a safe operation without discharge. Also,
Since the movable stub 13 can be freely operated during heating, it is possible to easily implement means for improving microwave characteristics by continuing to rotate the movable stub 13 during heating.

By the way, VS (voltage standing wave ratio) greatly changes depending on the load amount, and when the load weight of the object to be heated M is large to some extent, the amount of electromagnetic waves absorbed by the object to be heated M is large, so that the movable stub 13 operates. Therefore, VS does not increase until discharge occurs in the waveguide 12. Therefore, when the weight of the object to be heated M measured by the weight sensor 6 is larger than the comparative weight stored in advance in the memory of the control circuit 20, the magnetron 20 is transferred to the magnetron 20 during operation of the movable stub 13 during heating. It is also possible to avoid a temporary stopping operation of power supply and take the best heating means for all the objects M to be heated.

By the way, in the measurement for evaluating the heating efficiency of the high-frequency heating apparatus, as a load condition, as shown in FIG.
It is determined by the Electrical Appliance and Material Control Law and JIS standard that it can be put into K1 and BK2 separately. Since these 1 liter beakers BK1 and BK2 have a large bottom area, even if the 1 liter beakers BK1 and BK2 are placed on the turntable 3 so as to be deviated from the center, an extreme unbalanced load does not occur, and even if the turntable 3 is rotated and its weight is not measured, Weight (2kg + weight of beaker) can be measured without large error.

Generally, the high-frequency heating device periodically reads the weight data from the weight sensor 6 even during the heating standby state in which the heating operation is not performed, and when the object to be heated M is placed on the turntable 3. The data is transmitted to the control circuit 20. Therefore, this is applied when measuring the weight of the object to be heated M in the present embodiment, and the control circuit 20 judges whether the weight of the object to be heated M is 2 kg or more and 2 kg.
If it is above, the control circuit 20 will be the stub motor drive relay 7
3 is controlled to rotate the stub motor 15, and the movable stub 13 is immediately moved to the optimum position for the high frequency output measurement load.

This movement is carried out promptly after the weight measurement, and the user closes the door of the heating chamber 2 to set the heating time (time to increase the load for measuring the high frequency output by 10 ° C.) and start the heating. The operation of moving the position to the optimum position for the high-frequency output measurement load is completed. On the other hand, when the load is 2 kg or more and is not a high frequency output measurement load, the shape of the object to be heated M after heating is reviewed by checking the shape with the height sensor and the weight sensor, and the impedance suitable for the object to be heated M again. The movable stub 13 is rotated to the matching position.

As described above, by preliminarily estimating that the object M to be heated is a load for measuring the high frequency output before heating, the power feeding efficiency is highest for the load for measuring the high frequency output immediately after the start of heating. It is operated at the position of the movable stub 13. In addition, since the movable stub 13 is moved to a position where the high frequency output is maximized before heating, limiting the load for measuring the high frequency output, the maximum output can be generated during the high frequency output measurement, and a highly efficient device is realized. it can.

Next, the third embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. In this example, when performing cooking with a high-frequency output set low, such as thawing of frozen foods,
The position of the movable stub 13 is adjusted to an optimum position in order to operate the inverter power supply device continuously and at a low output, which is an embodiment corresponding to the invention of claim 3.

As the control device 70 in this embodiment,
The control device 70 shown in FIG. 8 is applied. However,
The height sensor and the weight sensor 6 including the light emitting element LD and the light receiving element PD may be omitted. When the frozen food is thawed by the high-frequency heating apparatus of this embodiment, the control circuit 20 reads the rotational position data of the movable stub 13 suitable for the object M to be thawed from the internal memory after the heating is started. , The stub motor drive relay 73 is controlled to control the energization time of the stub motor 15, and the movable stub 1
3 is moved to a position suitable for the object to be heated M to be thawed raw.

FIG. 11 shows the heating chamber 2 in which the object M to be thawed is placed on the turntable 3 and the movable stub 13 is rotated while the turntable 3 is stopped.
It is the figure which plotted the impedance of the side on the Smith chart. The numbers attached in the drawing indicate the rotational positions 0 to 15 (FIG. 35) of the movable stub 13, and the region surrounded by the diagonal lines is the maximum output region of the magnetron 10 in which the magnetron 10 operates most efficiently.

As is apparent from FIG. 11, when the object to be heated M is used as a load, the magnetron 10 has a movable stub 13
When the positions are set to 4 to 6, the most efficient operation is performed, and when the position is set to 12, on the other hand, the number of microwaves reflected by the magnetron 10 is large, and the output efficiency for the object to be heated M is lowered to heat the main body of the magnetron 10. To do. Therefore, the position suitable for the object to be heated M for thawing raw food is the position 12 in the case of the load shown in the Smith chart of FIG.

When the movable stub 13 is set to the position 12,
The output of the magnetron 10 is about 3/4 compared to position 4 (maximum output region of the magnetron). Therefore, in order to obtain the same output as compared with the case where the movable stub 13 is set to the position 4, it is necessary to increase the power supply amount to the magnetron 10 of the inverter circuit by 4/3.

Therefore, in the case of performing raw defrosting with the high-frequency heating apparatus of this embodiment, the control circuit 20 reads the rotational position data (position 12 in FIG. 11) of the movable stub 13 suitable for raw defrosting from the internal memory. By controlling the stub motor drive relay 73, the energizing time of the stub motor 15 is controlled to move the movable stub 13 to the position 12.

The control circuit 20 outputs a magnetron output setting signal for obtaining an output suitable for defrosting to the inverter control circuit 4
Although it is output to 0, the set value is 4/3 times the value when the movable stub 13 is at position 4. As a result, a sufficient filament current can be obtained by supplying 4/3 times the power to obtain the required high-frequency output, and continuous operation with weak output can be performed by the inverter power supply device.

When the movable stub 13 is set to the position 12 in this embodiment, the anode temperature of the magnetron 10 is set to the position 4.
However, in the case of raw thawing, the magnetron 10 can be operated without problems in the high frequency heating apparatus of this embodiment having a structure in which the amount of power supplied by the inverter circuit is small and sufficient cooling can be performed at high output. it can.

Next, the fourth embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. This embodiment is intended to prevent magnetron moding (abnormal oscillation).
It corresponds to the described invention. In this embodiment, the above-described block configuration diagram of the inverter power supply device 30 shown in FIG. 36 and the magnetron driving transformer shown in FIGS. 37 and 38 are applied.

FIG. 12 shows the waveform of the magnetron cathode voltage under normal conditions (FIG. 12A) and the corresponding output waveform of the detection winding 32e (FIG. 12B). Further, FIG. 13 shows the waveform of the magnetron cathode voltage at the time of abnormality (FIG. 13A) and the corresponding output waveform of the detection winding 32e (FIG. 13B). As is clear from both figures, a fluctuation appears at the bottom of the waveform of the magnetron cathode voltage during abnormal oscillation, and a differential change part corresponding to this change appears at the output of the detection winding 32e. The peak voltage level of the detection winding output during normal oscillation is V _N
The peak voltage level of the detection winding output during abnormal oscillation is V _A (V _N <V _A ).

FIG. 14 is a timing chart showing signals of respective parts of the detection winding output shaping circuit 50 (FIG. 36) when abnormal oscillation occurs. When abnormal oscillation occurs at time t1, a pulsed magnetron abnormal oscillation signal (FIG. A) is output from the comparison circuit 51 and is input to one of the AND circuits 52a of the determination circuit 52. At this time, the AND circuit 5
Gate signal of logic "H" is input to the other input of 2a (Fig. B)
, The pulsed magnetron abnormal oscillation signal is output as it is as a pulse generation trigger signal (FIG. 7C).

When the pulse generation circuit 53 receives this pulse generation trigger signal, it outputs to the inverter control circuit 40 a reset pulse (FIG. D) which becomes logical "H" for a certain period from time t2 to time t3. This allows the magnetron 10
Stops the oscillation from time t2 to time t3. Time point t3 is a time point when the re-oscillation of the magnetron 10 is started, and time point t4 is a time point when the oscillation of the magnetron 10 is stabilized. Time t
Even if the magnetron abnormal oscillation signal (Fig. A) is output from time 3 to time t4, the determination circuit 52 outputs the pulse generation trigger signal (Fig. C) because the gate signal (Fig. B) is logic "L". There is no such thing.

Next, the control method when the moding is detected will be described with reference to the flowchart shown in FIG. If the peak voltage level V _AP of the detection winding output V _A is higher than the peak voltage level V _NP of the threshold voltage V _N (step S10), a reset pulse is output from the detection winding output shaping circuit 50 as described above, The inverter control circuit 40 stops driving the switching circuit 34 (step S11), stops power supply to the magnetron 10, and stops continuous moding.

On the other hand, the control circuit 20 uses the magnetron 10
While the power supply to the magnetron 10 is stopped in order to return the stub motor 15 to the normal operation, the stub motor drive relay 73 is controlled to control the energization time of the stub motor 15 to keep the stub motor 15 constant. The movable stub 13 is rotated by a certain amount and is moved from the position of the impedance causing the moding (steps S12 to S14). afterwards,
The driving of the switching circuit 34 is restarted again to restart the power supply to the magnetron 10 (step S15), and the oscillation state of the magnetron 10 is returned to the normal operation.

When the moding occurs again after the microwave impedance in the heating chamber 2 is improved by temporarily stopping the power supply to the magnetron 10 and moving the movable stub 13, the magnetron 10 is temporarily stopped. The movable stub 13 is moved to a position where the moding is not completely generated by repeatedly stopping the power supply and moving the movable stub 13.

Next, the fifth embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. This embodiment corresponds to the invention described in claim 5, and like the above-mentioned fourth embodiment,
In order to prevent the modding (abnormal oscillation) of the magnetron, the block diagram of the inverter power supply device 30 shown in FIG. 36 and the magnetron driving transformer shown in FIGS. 37 and 38 are applied.

FIG. 16 is a flow chart for explaining the control method when the moding is detected according to this embodiment. First, the control circuit 20 recognizes the shape of the object to be heated (step S20). The shape recognition is performed by the height and weight of the object to be heated detected by the height sensor and the weight sensor described above. Then, the control circuit 20 reads the position data of the movable stub 13 from the recognized shape of the object to be heated from the internal memory (step S21), and further modifies the object to be heated having the recognized shape. It is determined (step S22). If the moding has occurred, the correction data is read from the internal memory (step S23), and the position data of the movable stub 13 is corrected by the correction data (step S24). Then, if no moding has occurred, step S
If moding has occurred based on the position data read from the internal memory in step 21, step S2
Based on the position data corrected in 4, the stub motor drive relay 73 is controlled, the energization time of the stub motor 15 is controlled, and the stub motor 15 is rotated by a certain amount.
The movable stub 13 is moved (step S25).

Then, the comparison winding 51 outputs the detection winding output V
_When it is detected that the peak voltage level V _{AP of A} has become larger than the peak voltage level V _NP of the threshold voltage V _N (step S26), it is determined that the modding has occurred in the magnetron 10, and the detection winding output shaping circuit 50 causes the inverter. As described above, the reset pulse is output to the control circuit 40, which causes the inverter control circuit 40 to stop the driving of the switching circuit 34 (step S27) and to stop the power supply to the magnetron 10 to stop the continuous moding. To do.

Then, the control circuit 20 controls the magnetron 1
Magnetron 10 to return the oscillation state of 0 to normal operation
While the power supply to the stub motor is stopped, the stub motor drive relay 73 is controlled to control the energization time of the stub motor 15, and the stub motor 15 is rotated by a certain amount to cause the movable stub 13 to be moded. It is moved from the position of the impedance (steps S28 and S29). Next, the energization time is integrated to control the movement amount of the movable stub 13 by integrating the energization time of the stub motor 15 (step S30), and the integration result is stored in the internal memory (step S31) to drive the stub motor. To control the movable relay 73 to stop the movable stub 13 (step S3
2) After that, the driving of the switching circuit 34 by the inverter control circuit 40 is restarted again to restart the power supply to the magnetron 10 (step S33), and the oscillation state of the magnetron 10 is returned to the normal operation.

When the moding occurs again after the microwave impedance in the heating chamber 2 is improved by temporarily stopping the power supply to the magnetron 10 and moving the movable stub 13, the magnetron 10 is temporarily stopped. The stop of the power supply and the movement of the movable stub 13 are repeated (steps S26 to S33), and the movable stub 13 is moved to the position where the moding is not completely generated.

As described above, the control circuit 20 calculates the amount of movement of the movable stub 13 from the detection of the moding to the time when the moding does not completely occur, by integrating the energization time to the stub motor 15 inside the control circuit 20. Store in memory.
As the internal memory, an E ² PROM whose stored contents can be electrically rewritten is desirable. The stored contents are retained even when power is not supplied to the control circuit 20 and the E ² PROM.

The moding avoidance operation is performed and E ² P
After the correction movement data of the movable stub 13 is stored in the ROM, when the shape data of the height and weight of the heated object M that has been heated matches the shape data of which the moding is detected, the object to be heated is Based on the height and weight of M, the position data of the movable stub 13 for optimum microwave impedance matching called from the storage element in the control circuit 20 is added with the correction data of the E ² PROM, and the stub motor drive relay 73 is added. Is controlled to rotate the stub motor 15 to move the movable stub 13 to a position for optimum impedance matching that does not cause moding, and microwave heating is performed.

Next, the sixth embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. The present embodiment corresponds to the invention described in claim 6. In the above-described second embodiment (FIG. 6), the height and weight of the object to be heated M are measured to adjust the position of the movable stub 13, but a container for the object to be heated M is used. If the height and weight are extremely different from those of the average container, it will be erroneously determined. Therefore, in the present embodiment, the heating efficiency of the microwave to the object to be heated M is detected by the temperature change of the magnetron 10, and the control circuit 20 directly detects the radiation state of the microwave to the object to be heated M, and the movable stub 13 Is operated to improve the microwave impedance matching.

FIG. 17 is a block diagram of the high-frequency heating apparatus according to this embodiment, which has a structure in which a thermistor TH is attached to the outer shell of the magnetron 10. The other structure is the same as the structure shown in FIG. FIG. 18 shows the controller 7 of this embodiment.
In the block diagram of 0, the thermistor TH and the detection resistor R are connected in series and connected to the DC power supply Vd, and the connection midpoint of the thermistor TH and the detection resistor R is connected to the control circuit 20 via the interface 21. The other structure is the same as the structure shown in FIG.

The thermistor TH has a characteristic that its resistance value decreases as its temperature rises, and the voltage across the detection resistor R connected in series increases as the resistance value of the thermistor TH decreases. The control circuit 20 can detect the temperature change of the thermistor TH, that is, the temperature change of the magnetron 10 as the voltage change of the detection resistor R.

On the other hand, during microwave heating, the control circuit 2
0 controls the cooling fan drive relay 72 to drive the magnetron cooling fan motor FM, sucks the outside air, and blows cool air to the magnetron 10 and the half-wave voltage doubler circuit VM that supplies electric power to the magnetron 10 for cooling. The heat generation amount of the magnetron 10 is changed by the microwave impedance matching of the waveguide 12 to which the magnetron 10 is attached and the heating chamber 2 to which the magnetron 10 is connected, and the magnetron 10 efficiently radiates microwaves to the object to be heated M. When it is present, the energy loss of the magnetron 10 is small and its temperature is relatively low.

On the contrary, when the microwave M is not efficiently radiated to the object to be heated M, the number of reflected waves to the magnetron 10 increases and the temperature of the magnetron 10 rises. The magnetron temperature rises at a high speed with the start of power supply to the magnetron 10, and the temperature is about 60% of the saturation temperature at which the cooling capacity and the heat radiation amount of the magnetron 10 are balanced under the same load and the same impedance matching condition. It rises in a minute, and the rate of increase is almost constant during that time.

Next, the control procedure of this embodiment will be described with reference to the flow chart shown in FIG. When the microwave heating is started, the control circuit 20 controls the cooling fan drive relay 72 to control the magnetron cooling fan motor F.
By driving M and simultaneously controlling the heating relay 75 to supply power to the voltage doubler circuit VM, power is supplied to the magnetron 10 and the microwave is radiated from the magnetron 10 (step S40). Further, the control circuit 20 detects the detection resistance R at the same time when the magnetron 10 starts to increase its temperature.
Is periodically measured (steps S41 to 43), the temperature gradient data Y is calculated (step S44), and the position data X and the temperature gradient data Y of the movable stub 13 are stored (step S45). If the position data X is not the position of position 4 (step S46), the stub motor drive relay 73 is controlled to rotate the stub motor 15 to move the movable stub 13 by a certain amount with the position 0 as the first position ( In step S47), the rate of change of the magnetron temperature per unit time at each stop position is measured (steps S41 to S45).

FIG. 20 is a graph showing the relationship between the stop position of the movable stub 13 and the rate of change of the magnetron temperature when a certain object M to be heated is heated in the heating chamber 2, and the relationship is the object M to be heated. It depends on the shape of. The control circuit 20 determines that the position where the voltage change gradient of the detection resistor R per unit time is the smallest is the position of the optimum movable stub. Taking the object to be heated shown in FIG.
Between 4 the optimum output point is position 2.

By the way, the waveguide 12 is shown in FIG.
The locus of impedance matching with respect to the movement of the movable stub 13 is symmetrical from the position 12 to the position 0 from the opening side with respect to the broken line DL shown in (a diagram for explaining the rotational position of the movable stub 13). The path from the position 4 to the position 4 is traced in reverse by the movement from the position 4 to the position 8 to the position 12. The control circuit 20 calculates the amount of rotation of the movable stub 13 from position 2 to position 4 by integrating the energization time to the stub motor 15, and moves the movable stub 13 from position 4 to position 6 which is the target position. Let it stop.
This position is the position of the optimum output point having the same impedance matching as position 2.

This high-frequency heating device performs this control at an early stage of heating, and thereafter continues heating at the position of the movable stub 13 for impedance matching of optimum output until the heating is completed. That is, when the position data X of the movable stub 13 reaches the position of position 4 (stab S46), the movable stub position where the temperature gradient is minimized is recognized (stab S50),
The operation time T2 of the stub motor 15 from the movable stub position where the temperature gradient is the minimum to the position 4 is calculated (step S51), and the stub motor drive relay 73 is turned on to drive the stub motor 15 (step S52). ), When the time T2 has elapsed, the stub motor drive relay 73 is turned off to stop the stub motor 15 (stub S53,
S54).

By the way, in the present embodiment, when the magnetron 10 modifies, the electrons in the magnetron 10 do not operate normally and are converted into heat in the tube. Magnetron 1 when moding occurs continuously
0 cannot radiate microwaves, and most of the electric power supplied to the magnetron 10 is converted into heat. The microwave conversion efficiency of the magnetron 10 is around 70% in normal operation, and the rest is converted into heat, etc., and the cooling capacity of the magnetron cooling fan motor FM is at a temperature sufficient for normal operation of the magnetron 10. It has the ability to maintain, but when the magnetron 10 modifies, the heat radiation amount of the magnetron 10 rapidly increases, exceeding the cooling capacity of the magnetron cooling fan motor FM, and rapidly increasing the temperature of the magnetron 10, and by this rise. The modding is promoted, causing the magnetron 10 to run into heat and run into destruction.

The cause of moding is related to the microwave impedance matching of the cavity constituted by the waveguide 12 to which the magnetron 10 is connected, the heating chamber 2 connected to it, and the load placed in the heating chamber 2. However, the position of impedance matching where moding is likely to occur is generally near the maximum output region of the magnetron 10. FIG. 21 shows changes in the magnetron temperature during normal operation with respect to the elapsed heating time.
Figure 3 shows the change in magnetron temperature when the moding occurs with respect to the elapsed heating time. As is clear from this figure, the temperature of the magnetron 10 usually rises with a constant gradient immediately after heating, and eventually saturates at a certain temperature and maintains that temperature. However, when the magnetron 10 is moded and the temperature of the magnetron 10 is rising, a change occurs in the rising gradient and the gradient becomes large from the moding occurrence point. If it is saturated, the temperature starts to rise again.
Further, regardless of whether the occurrence of moding is during the temperature rise of the magnetron 10 or after the saturation, it continues to rise beyond the normal saturation temperature point of the magnetron 10.

Therefore, after calculating the temperature gradient data Y as shown in the flowchart of FIG. 23 (step S4)
4) If the heating is not completed (step S60),
It is determined whether the temperature gradient has become large (step S6).
1). As a result, if the temperature gradient is large, the heating relay 75
Is controlled to cut off the electric power supplied to the half-wave voltage doubler circuit VM to stop the electric power supply to the magnetron 10, and to continue driving the magnetron cooling fan motor FM while stopping the continuous moding to keep the temperature of the magnetron 10. Is lowered (step S62). Then, the stub motor driving relay 73 is controlled to control the energization time of the stub motor 15 to rotate the stub motor 15 by a certain amount, and the movable stub 1
3 is moved from the position of the impedance that caused the moding (step S63). After that, the power supply to the magnetron 10 is restarted again to return the oscillation state of the magnetron 10 to the normal operation (step S64).

When the moding occurs again after the microwave impedance in the heating chamber 2 is improved by temporarily stopping the power supply to the magnetron 10 and moving the movable stub 13, the magnetron 10 is temporarily stopped. The movable stub 13 is moved to a position where the moding is not completely generated by repeatedly stopping the power supply and moving the movable stub 13.

Next, another control method of the high frequency heating apparatus (FIGS. 17 to 18) according to this embodiment will be described. FIG.
FIG. 25 is a graph showing changes in the rate of change of the magnetron temperature per unit time due to changes in the position of the movable stub 13 during heating of the object Ma (or Mb) to be heated, and FIGS. 25 and 26 show the control method. It is a flowchart.

25 and 26, when microwave heating is started, the control circuit 20 controls the cooling fan drive relay 72 to drive the magnetron cooling fan motor FM and the heating relay 75 to control the half-wave voltage doubler. Circuit VM
The electric power is supplied to the magnetron 10 so that microwaves are radiated from the magnetron 10. At the same time, the control circuit 20 performs shape recognition based on the height and weight of the object to be heated M measured after the turntable 3 makes one rotation (step S70).

Then, the control circuit 20 judges whether or not the recognized group of the objects to be heated M has been heated before (step S71), and if it has been heated before, it is judged from the internal memory (for example, E ² PROM). Movable stub 1 at that time
The position data of No. 3 is read (step S72), and it is further determined whether or not the object to be heated M having the recognized shape has undergone moding (step S73). If the moding has occurred, the avoidance data is read from the internal memory (step S74), and the position data of the movable stub 13 is modified by the avoidance data (step S75).

Next, when the control circuit 20 determines in step S73 that the moding has not occurred,
Based on the position data read from the internal memory in step S72, if moding has occurred, the stub motor drive relays 73 are controlled based on the position data modified in step S75, respectively.
Is controlled (step S76), and when the movable stub 13 moves to the position for optimum impedance matching (step S77), the stub motor drive relay 73 is turned off and the movable stub 13 is stopped (step S77). S78).

On the other hand, the control circuit 20 recognizes the object M to be heated.
When it is determined that the group No. has not been heated before (step S71), the voltage of the detection resistor R is periodically measured simultaneously with the heating (steps S90 to 92), and the temperature gradient data Y is calculated (step S90). S93), the current position data X and the temperature gradient data Y of the movable stub 13 are stored (step S94). Next, if the position data X is not at position 4, the control circuit 20 (step S
95), controlling the stub motor drive relay 73 to rotate the stub motor 15 to move the movable stub 13 by a fixed amount starting from position 0 (step S96), and change in magnetron temperature per unit time at each stop position. The rate is measured (steps S90 to S94).

The position data X of the movable stub 13 is the position 4
Then, the position of the movable stub 13 that minimizes the temperature gradient is recognized (stap S97), and the movement amount P from the position 4 to the optimum stub position and the target position is calculated (step S98). Motor drive relay 73
Is turned on to drive the stub motor 15 (step S9).
9). When the movable stub 13 moves by the movement amount P (stub S100), the control circuit 20 turns off the stub motor drive relay 73 to stop the stub motor 15 (stab S101), and the optimum movable stub position is set in the control circuit 20. The data is stored in the internal memory (for example, E ² PROM) (stap S102). The E ² PROM is a memory element whose stored contents can be electrically rewritten freely, and the stored contents are retained even if power is not supplied to the control circuit 20 and the E ² PROM.

When the processing of step S78 or step S102 is completed, the control circuit 20 determines whether or not the heating is completed (step S79). If the heating is not completed, the magnetron 10 is not moding. Detecting (stap S80), if the moding has not occurred, the processes of steps S79 to 80 are repeated until the heating is completed.

When the magnetron 10 causes the moding, if the temperature of the magnetron 10 is rising, a change appears in the rising gradient and the gradient becomes large. If it is saturated, the temperature starts rising again from there. Further, whether or not the modding occurs during the temperature rise of the magnetron 10 or after the temperature rises, the temperature continues to rise beyond the normal saturation temperature of the magnetron 10. When the control circuit 20 detects the change in the magnetron temperature due to the occurrence of the moding from the voltage of the detection resistor R and determines that the magnetron 10 is in the moding (step S80), it controls the heating relay 75 to perform half-wave multiplication. The power supply to the magnetron 10 is stopped by cutting off the power supplied to the voltage circuit VM (step S8).
1), the magnetron cooling fan motor FM is continuously driven while stopping the continuous moding, and the magnetron 1
Decrease the temperature of 0. The high-frequency heating device having an inverter circuit as a power supply source to the magnetron 10 is
The modding of the magnetron 10 is detected by the method described above.

Next, the control circuit 20 operates the magnetron 10
In order to return the oscillating state of the stub to the normal operation, the stub motor drive relay 73 is controlled to control the energization time of the stub motor 15 to rotate the stub motor 15 by a certain amount during the period in which the power supply to the magnetron 10 is stopped. , Movable stub 13
Is moved from the position of the impedance that caused the moding (step S82), and then the power supply to the magnetron 10 is restarted to return the oscillation state of the magnetron 10 to the normal operation (step S83). The moving amount is stored in the E ² PROM in the control circuit 20 by integrating the energization time to the stub motor 15 (step S8).
4) and returns to step S79.

When the heating is completed (step S79), the control circuit 20 controls the heating relay 75 to cut off the electric power supplied to the half-wave voltage doubler circuit VM so that the magnetron 1 can operate.
0 is stopped (step S85), the cooling fan drive relay 72 is controlled to cut off the power supplied to the cooling fan motor FM to stop the cooling fan motor FM (step S86), and the processing is executed. finish.

As described above, in this control method, as shown in steps S70 to S78, after the position of the optimum impedance matching is corrected, the height and weight of the object to be heated M newly heated is adjusted. If the shape data matches the shape data stored in the E ² PROM, the optimum microwave impedance matching called from the memory element in the control circuit 20 based on the height and weight of the object to be heated M. E ² for position data of movable stub 13
The stub motor driving relay 73 is driven in consideration of the correction data of the PROM to rotate the stub motor 15, and the movable stub 13 is quickly moved to the position of the optimum impedance matching.

Further, when the shape data is obtained, the moding avoiding operation is performed and the movable stub 1 is added to the E ² PROM.
When the corrected movement data of No. 3 is stored, the position of the movable stub 13 is learned by adding the data of the position where moding does not occur to the position of the optimum impedance matching, and the position of the movable stub 13 is determined. To do. This is because the position of impedance matching where moding is likely to occur is generally near the maximum output region of the magnetron 10.

For example, if there is a heated object Ma and a heated object Mb having the same shape recognition data, the position of the movable stub 13 stored in the storage element of the control circuit 20 of the shape data in advance is 1. Suppose there is. The position of the movable stub 13 is a position at which the magnetron 10 does not cause a modding to any load included in the shape recognition data. Movable stub 1 while heating object Ma
The change in the rate of change of the magnetron temperature per unit time with the change in the position of 3 is as shown by line a in FIG. 24, and the control circuit 20 determines that the position of the movable stub 13 is 3 and the position of the optimum impedance matching. When it is determined that there is, the contents are stored in the E ² PROM.

On the other hand, when the object to be heated Mb is heated, the control circuit 20 judges from the height and weight data that the shape data is the same as that of the object to be heated Ma, and the movable stub is stub according to the data stored in the E ² PROM. Motor drive relay 7
3 is controlled to rotate the stub motor 15 to move it to the position 3. When moding occurs during heating at the position 3 of the movable stub 13 and the control circuit 20 detects the moding, the stub motor drive relay 73 is controlled to rotate the stub motor 13 and the moding occurs at the position 6. If it can be avoided, the change in the rate of change of the magnetron temperature per unit time with the change in the position of the movable stub 13 is shown in FIG.
It becomes like the line b of 4.

The waveguide 12 is made symmetrical with respect to the opening side with respect to the broken line DL in FIG. 35, and the locus of impedance matching with respect to the movement of the movable stub 13 passes from position 12 to position 0. Position 4 on the locus to 4
The position is traced in the opposite direction by moving from the position 8 to the position 12. The control circuit 20 determines that the area between the position 6 and the target position, that is, the positions 2 to 6 is the moding region of the object to be heated M. After that, when the heated object M classified into the same shape as the heated objects Ma and Mb is heated, the control circuit 20 outputs the position data 3 of the optimum impedance matching of the movable stub 13 obtained from the heated object Ma as E. ^{2 While} reading from PROM,
Moding area data (position 2) obtained from the object to be heated Mb
6) is read from the E ² PROM, the microwave heating efficiency is the highest in the non-moding area, and the position 2 closest to the position of the movable stub 13 at the start of heating is the same as the objects Ma and Mb to be heated. It is determined that the position of the movable stub 13 of the object M to be heated classified into the shape, the stub motor driving relay 73 is controlled to rotate the stub motor 15, and the movable stub 13 is moved to the position 2 for heating. Let it start.

Next, the seventh embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. In this embodiment, two magnetrons are vertically provided on the side wall of the heating chamber, and the uniform heating characteristic of the object to be heated is improved by selecting the magnetron wave feeding opening according to the shape of the object to be heated. The invention corresponds to the invention described in claims 7 and 8.

In this embodiment, as shown in FIG. 27, the side wall of the high-frequency heating apparatus is provided with an opening 7A having excellent flat uniform characteristics and an opening 7B having excellent upper and lower uniform heating characteristics. The opening 7A has a magnetron 10A. A waveguide 12A for guiding microwaves radiated from the heating chamber 2 is provided, and a waveguide 12B for guiding microwaves radiated from the magnetron 10B to the heating chamber 2 is provided at the opening 7B. Other configurations are the same as the configurations shown in FIGS. 1 and 6 described above. The movable stub 1 installed in the waveguides 12A and 12B
3, the stub motor 15 and the like are omitted.

Further, the control device 70 of this high-frequency heating device.
As shown in FIG. 28, the power supply line from the half-wave voltage doubler circuit VM including the high-voltage transformer 32, the high-voltage capacitor 35, and the high-voltage diode 36 to the magnetrons 10A and 10B is connected via the contact 72 of the high-voltage switching relay 71. The high voltage switching relay 7 is connected to each of the magnetrons 10A and 10B and receives a signal from the control circuit 20.
The structure is such that 1 is switched to select a magnetron for supplying electric power. Other configurations are the same as the configurations shown in FIG. 3 described above, but the infrared sensing device 60 is unnecessary,
The outputs of the weight sensor 6 and the light receiving element PD are input to the control circuit 20 via the interface 21.

In this embodiment, when heating is started, a plurality of light emitting elements LD are provided on the wall surface of the heating chamber 2 at regular intervals in the vertical direction, and the same height relationship is provided on the wall surface facing the light emitting element LD. The height measurement sensor including the same number of light emitting elements PD measures the height of the object to be heated M, and the weight sensor 6 measures the weight of the object to be heated M to recognize the shape of the object to be heated M. The details of this shape recognition operation have been described above, and will be omitted.

Based on the shape of the object to be heated M, the control circuit 20 judges which of the opening 7A having excellent average uniform heating characteristics and the opening 7B having excellent upper and lower uniform heating characteristics is suitable for the object M to be heated. The high voltage switching relay 7
1 corresponding to the aperture determined by controlling 1
0A or 10B is connected to the half-wave voltage doubler circuit VM, and the heating relay 75 is driven to supply power to the determined magnetron 10A or 10B to radiate a microwave to heat the object to be heated M. According to the present embodiment, since the shape of the object to be heated M can be recognized and the opening that matches the shape can be selected and heated, a high-frequency heating device having excellent uniform heating characteristics for any load is realized. it can.

In this case, the control circuit 20 radiates microwaves from the opening 7A having an excellent average uniform heating characteristic and microwaves from the opening 7B having an excellent uniform heating characteristic on the basis of the shape recognition data of the object M to be heated. Unit of each magnetron 10A or 10B by deciding the ratio of the radiation and periodically switching the high-voltage switching relay 71 during heating and switching the switching relay 71 at the power supply time ratio of the same ratio as the radiation ratio. You may make it implement | achieve the uniform heating according to the shape of the to-be-heated material M by controlling the electric power supply amount per time. By doing so, the opening for radiating microwaves can be periodically changed during heating, so that it is possible to realize a high-frequency heating apparatus having more excellent uniform heating characteristics according to the shape of the object to be heated M.

FIG. 29 is a block diagram showing a modification of the control device 70 in this embodiment (FIGS. 27 to 28). This control device 70 is a rectifying / smoothing circuit that eliminates the heating relay 75 in the control device 70 shown in FIG. 29 and replaces it with a power supply circuit that supplies electric power to the magnetrons 10A and 10B by rectifying and smoothing a commercial power supply to obtain a DC power supply. 31
On the output side of the two magnetrons 10A, 10B for driving the magnetron 32A, 32B, the transformer 32
Resonant capacitors 33A and 33B and semiconductor switching circuits 34A and 34B connected in parallel to the primary windings 32aA and 32aB of A and 32B are provided, and ON / OFF pulse signals for high frequency switching the semiconductor switching circuits 34A and 34B are changed. Magnetron 10
An inverter circuit that limits the amount of power supplied to A and 10B is connected.

On the secondary side of the transformers 32A and 32B, secondary windings 32bA and 32bB have high voltage capacitors 35A and 32B.
B and the high voltage diodes 36A and 36B are connected to form a voltage doubler circuit VM, which is connected to the magnetrons 10A and 10B as a magnetron drive circuit. The cathodes of the magnetrons 10A, 10B are capacitors 35A, 35
It is connected to the interface 21 via B and the secondary windings 32bA and 32bB.

Further, the secondary winding 3 of the transformers 32A and 32B
The resistors 37A and 37B connected to the interface 21 side of 2bA and 32bB are magnetron anode current detection resistors, and the voltage across the resistors 37A and 37B is input to the interface 21. Also, the magnetron 10A,
Heater winding 32c for heating 10B filament
A and 32cB are connected to the magnetron anode, and the anode voltage of the magnetrons 10A and 10B is controlled by the signal from the control circuit 20. Further, the control windings 32dA and 32dB on the temporary side of the transformers 32A and 32B are input to the interface 21 for synchronization and output voltage detection.

In the present embodiment, when heating is started, the control circuit 20 recognizes the shape of the object M to be heated by the height sensor and the weight sensor, and based on this shape recognition data, the opening 7A having excellent planar uniform heating characteristics. The ratio of the microwave radiation from the antenna and the microwave radiation from the opening 7B having excellent upper and lower uniform heating characteristics is determined, and each inverter power supply radiates to each magnetron 10A, 10B by the output control signal from the control circuit 20. Electric power corresponding to the ratio is supplied to simultaneously radiate microwaves having different outputs. Therefore, according to the present embodiment, the microwaves can be simultaneously radiated from the two openings according to the shape recognition data of the object to be heated M, and the ratio of the microwaves radiated from each opening can be freely changed. Furthermore, it is possible to realize a high frequency heating device having excellent uniform heating characteristics.

Next, the eighth embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. This embodiment is an embodiment corresponding to the invention of claim 9 in which the finish of the object to be heated is accurately detected when the object to be heated is covered with wrap and steamed for cooking. In this embodiment, in the high-frequency heating apparatus having the configuration shown in FIG. 6, when the object to be heated M is covered with the wrap L as shown in FIG. 30 and cooked, the height sensor finishes the object to be heated. It is something to detect. Note that FIG. 30 (a) shows the state of the lap L before heating, and FIG. 30 (b) shows the state of the lap L just before the end of heating.

In the high-frequency heating device having the function of measuring the height of the object to be heated M, as described above, the plurality of light emitting elements LD are provided on the wall surface of the heating chamber 2 in the vertical direction at regular intervals. Further, the same number of light receiving elements PD are provided on the opposing wall surfaces in the same height relationship as the light emitting elements LD. The light emitting element LD and the light receiving element PD are laid out so that the light emitted from the light emitting element LD passes through the center of the turntable 3 or the vicinity thereof and strikes the light receiving element PD.

In the high frequency heating apparatus of this embodiment, since the waveguide 12 and the magnetron 10 are located in the center of the right side wall of the heating chamber 2, the light emitting element LD is located behind the right side wall of the heating chamber 2 and the light receiving element is located. The PD is arranged in front of the left side wall of the heating chamber 2 on the line connecting the center of the turntable 3 and the light emitting element LD, corresponding to the light emitting element LD. When the object M to be heated is placed on the turntable 3 and heating is started, the control circuit 20 controls the turntable drive relay 74 to rotate the turntable motor 5 to rotate the object M to be heated on the turntable 3. Meanwhile, each output level of the light receiving element PD is measured.

The purpose of rotating the object to be heated M during height measurement is to position the object to be heated M between the light emitting element LD and the light receiving element PD when the object M to be heated is eccentric on the turntable 3. If the object M to be heated is positioned between the light emitting element LD and the light receiving element PD by rotating, assuming that the light of the light emitting element LD is not correctly blocked (the light emitting element LD and the light receiving element PD are connected to each other). This is to create an overlapping line (the line connecting the center of the turntable 3 with the spiral line, the object M to be heated).
The control circuit 20 reads the output signal of the light receiving element PD while the turntable 3 rotates, and the light from the light emitting element LD is blocked during the rotation (the output level of the light receiving element PD becomes zero). The height to the element PD is determined as the height of the object to be heated M.

Since the object to be heated M shown in FIG. 30A blocks only the light entering the lowest level H of the light receiving elements PD, the height of the lap L before heating becomes the level H. The object to be heated M of the present embodiment is covered with a wrap L in order to steam and heat the object to be heated M by confining water vapor emitted from itself in a closed space. When microwave heating is started, the control circuit 20 measures the height of the lap L (that is, the object to be heated M) before heating, and controls the heating relay 75 to supply power to the half-wave voltage doubler circuit VM. Then, electric power is supplied to the magnetron 10 to radiate microwaves from the magnetron 10.

The object to be heated M heated by the microwave radiated from the magnetron 10 emits water vapor from itself as the temperature rises. This water vapor fills the space sealed by the wrap L and increases the pressure in this space. As the pressure of the space sealed by the wrap L rises, the wrap L loses the pressure and expands upward, and enters between the light emitting element LD and the light receiving element PD which have been transmitted before heating and enters the light receiving element PD. The output voltage of the light receiving element PD is changed by closing the light source to As shown in FIG. 30 (b), the lap L just before the end of heating blocks the light entering the photodetector PD of levels F, G, and H,
The height data is level F. The control circuit 20 catches the output change of the light receiving element PD, recognizes the expansion of the lap L, and finishes the heating.

Next, the ninth embodiment of the high-frequency heating apparatus according to the present invention
An example will be described. The present embodiment corresponds to the invention of claim 10. 31 (a) and (b)
[Fig. 3] is a front vertical cross-sectional view and a horizontal cross-sectional view of the high-frequency heating device according to this embodiment. In this embodiment, a plurality of light emitting elements LD are horizontally provided at a constant interval on the wall surface of the heating chamber 2 at a position slightly above the turntable 3, and the opposite wall surfaces have the same height and the same front-back relationship. Are provided with the same number of light receiving elements PD, and the light emitted from the light emitting elements LD hits the light receiving elements PD in parallel behind or in front of the center of the turntable 3. PD and PD are laid out.
In this embodiment, the light emitting element LD and the light receiving element PD are arranged in the rear half of the turntable 3.

In this embodiment, when the object M to be heated is placed on the turntable 3 and heating is started, the control circuit 20 controls the turntable motor drive relay 74 to rotate the turntable motor 5 to turn the turntable motor 5. The output level of each of the light receiving elements PD is measured while rotating the object to be heated M on 3. The purpose of rotating the object to be heated M at the time of measurement is that the line connecting the end of the object to be heated M on the turntable 3 (the part from the outermost periphery) and the center of the turntable 3 emits light from the light receiving element PD. This is because the measurement needs to be performed when the line connecting the elements LD is orthogonal to each other, and that point (most of which is the light emitting element LD
The position of the object to be heated M is recognized by the point where the light from the is blocked.

The control circuit 20 reads the output signal of the light receiving element PD while the turntable 3 rotates, and the light from the light emitting element LD is blocked during rotation from the center of the turntable 3 (that is, of the light receiving element PD). The light receiving element PD located at the innermost position (when the output level becomes zero) (“U” in FIG. 31)
Position) is determined as position data of the object to be heated M.

In this case, at what position is the object M to be heated with respect to the opening for radiating microwaves in the integrated time of the energization time to the turntable 3 after the innermost light receiving element PD is shielded? To judge. Based on this data, the control circuit 20 controls the output control signal of the inverter circuit when the object M to be heated passes near the opening, and supplies the power to the magnetron 10 only when the object M to be heated is positioned in front of the opening. The supply amount is reduced to avoid the moding, and when the object to be heated M separates from the opening, it is returned to the power supply amount again. In this way, the increase and decrease of the power supply amount to the magnetron 10 are repeated in synchronization with the rotation of the turntable 3 until the heating is completed.

In this way, the power supply to the magnetron 10 is momentarily stopped only when the object M to be heated placed on the outer circumference of the turntable 3 is positioned in front of the opening.
Alternatively, in order to avoid the moding by reducing the power supply amount to an amount that is not sufficient to cause the moding, the object to be heated M can be heated with an optimum microwave impedance at a position other than the position where the opening is closed with high efficiency. It is possible to realize a high-frequency heating device that does not cause ding.

Further, in the configuration of the above-described embodiment (FIG. 31) for measuring the position of the object to be heated M, as shown in the second embodiment (FIGS. 6 to 8), the height of the object to be heated M and It is also possible to use the function of measuring the weight. In this case, when the object to be heated M is placed in the heating chamber 2 and the heating operation is performed,
The control circuit 20 controls the turntable driving relay 74 to supply power to the turntable motor 5 and rotate the turntable motor 5 to measure the height and weight of the object to be heated M. During this time, the movable stub 13 controls the stub motor drive relay 73 in advance by the control circuit 20 after the previous heating, and the position where VS (voltage standing wave ratio) is low with respect to any load (stop position shown in FIG. 35). It remains stopped at 0).

On the other hand, the control circuit 20 simultaneously reads the output signals of the light receiving elements PD arranged in the horizontal direction while the turntable 3 rotates while measuring the height and weight of the object to be heated M, and outputs the output signal of the turntable 3. The light from the light emitting element LD is blocked during rotation from the center (the output level of the light receiving element LD becomes zero) and the distance to the light receiving element PD located at the innermost position is determined as the position data of the object to be heated M. To do.

Based on the height, weight and position data of the object to be heated M thus obtained, the control circuit 20 outputs the position data of the movable stub 13 for the recognized shape to the control circuit 2.
0 is called from the memory element, and it is judged from the position data of the object to be heated M whether or not the object to be heated M causes the moding. The correction data for moving the movable stub 13 to the position that does not cause the moding stored in the memory is called to move the movable stub 1 to the shape.
The position data of No. 3 is corrected, and the movable stub 13 is moved with the correction. By doing so, the movable stub 13 is located at the position of the optimum impedance for the object to be heated M, and a high-efficiency high-frequency heating device can be realized.

In this case, the control circuit 20 is based on the height, weight and position data of the object to be heated M obtained by measurement.
Calls the position data of the movable stub 13 for the recognized shape from the storage element of the control circuit 20, determines from the position data of the object to be heated M whether or not the object to be heated M causes the moding, and at the position to raise the object. In some cases, it is further determined based on the height data whether or not the object to be heated M is at a height that covers the opening radiating the microwave. And
When the height is so as to cover the opening, the control circuit 20 calls the correction data stored in the storage element in advance to move the movable stub 13 to the position where the moding does not occur, and the movable stub 13 corresponding to the shape is called. Is corrected and the stub motor drive relay 73 is controlled based on the data to rotate the stub motor 15 to move the movable stub 13. By doing so, it is possible to realize a high-frequency heating device that does not cause moding with high efficiency for many objects M to be heated.

[0178]

According to the first aspect of the invention, in a menu in which the physical properties of the object to be heated change, infrared rays or radiant heat emitted from the object to be heated by an infrared sensor or thermistor provided on the wall or top of the heating chamber. It is possible to realize a high-efficiency high-frequency heating device capable of detecting the surface temperature of the object to be heated by non-contact measurement, and performing impedance matching optimal for each physical property before and after the melting point as a boundary.

According to the second aspect of the invention, the power supply to the magnetron is momentarily stopped or the power supply is stopped only when the movable stub passes through the position where the voltage standing wave ratio (VS) becomes high. By suppressing the amount to be equal to or less than the amount of electric power sufficient for discharging, the extension of the heating time by the discharge preventing means can be reduced with respect to the total heating time, so that a highly efficient and safe high-frequency heating device can be realized. Further, since the movable stub can be freely operated during heating, it is possible to easily implement means for improving the microwave characteristics by continuing to rotate the movable stub during heating.

According to the third aspect of the present invention, the inverter circuit can be operated continuously and at a low output without preparing a transformer for heating the filament, so that the uniform heating property is excellent and the cost is low. It is possible to realize a high-frequency heating device that has plenty of space for installing other parts.

According to the fourth aspect of the invention, when the moding occurs, the position of the movable stub is changed to change the microwave impedance in the heating chamber containing the object to be heated to change the microwave in the heating chamber. Since the impedance is removed from the impedance position that causes the moding, the moding does not occur again until the heating is completed. In addition, since the microwave impedance can be determined in accordance with the magnetron whose moding resistance is lowered toward the end of its life, a high-frequency heating device with high efficiency and long life can be realized.

According to the fifth aspect of the present invention, the shape data in which the moding has occurred and the position of the movable stub after avoiding the moding are stored, and the shape to be stored by the object to be heated thereafter is stored. When the data is classified into the same group as the data, the control circuit determines the movable position by adding the position data of the movable stub that avoids the moding, so there is no risk of causing the moding after that. Since it is not necessary to select an impedance that does not cause moding for all objects to be heated and its state, it is possible to select the most suitable microwave impedance for the objects to be heated, and to provide a high-frequency heating device that does not cause moding with high efficiency. realizable.

According to the invention of claim 6, since the radio wave radiation state of the magnetron to the object to be heated can be directly judged from the temperature change of the magnetron, regardless of the shape or weight of the container for containing the object to be heated. By determining the position of the movable stub that creates the optimum microwave impedance for the object to be heated, a highly efficient high frequency heating device can be realized.

According to the seventh and eighth aspects of the invention, the shape of the object to be heated is recognized, the opening suitable for the shape is selected, the opening is periodically changed, and the micro-radiation from each opening is performed. Since both openings can be selected and heated at the same time while changing the wave ratio, it is possible to realize a high-frequency heating device having excellent uniform heating characteristics for all loads.

According to the ninth aspect of the invention, since the bulge of the wrap covering the object to be heated can be directly detected, it is possible to realize a high-frequency heating apparatus capable of accurately detecting the finish of the object to be heated wrapped.

According to the tenth aspect of the present invention, since the position of the object to be heated placed on the turntable can be accurately recognized, by determining the position of the movable stub according to the position, the efficiency can be improved. It is possible to realize a high-frequency heating device that does not cause moding.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a high-frequency heating device according to the present invention.

FIG. 2 is an enlarged view of the infrared sensing device shown in FIG.

3 is a block diagram showing a control device of the high-frequency heating device shown in FIG.

FIG. 4 is a diagram in which impedance when the object to be heated is placed in the heating chamber and the turntable is rotated is plotted on a Smith chart.

FIG. 5 is an enlarged view of a radiant heat sensor.

FIG. 6 is a configuration diagram showing a second embodiment of the high-frequency heating device according to the present invention.

FIG. 7 is an enlarged view of the weight sensor.

8 is a block diagram showing a control device of the high-frequency heating device shown in FIG.

FIG. 9 is a diagram in which a change in impedance on the heating chamber side when a movable stub is rotated is plotted on a Smith chart.

FIG. 10 is a diagram for explaining load conditions at the time of measurement for evaluating heating efficiency of the high-frequency heating device.

FIG. 11 is a diagram in which the impedance on the heating chamber side when the turntable is stopped and the movable stub is rotated is plotted on a Smith chart.

FIG. 12 is a waveform diagram showing a magnetron cathode voltage and a detection winding output corresponding thereto in a normal state.

FIG. 13 is a waveform diagram showing a magnetron cathode voltage and a detection winding output corresponding to the voltage when an abnormality occurs.

FIG. 14 is a timing chart showing an abnormal oscillation signal and a gate signal during normal times.

FIG. 15 is a flow chart showing a control method when a moding is detected in the fourth embodiment of the high-frequency heating apparatus according to the present invention.

FIG. 16 is a flow chart showing a control method when a moding is detected in a fifth embodiment of the high-frequency heating device according to the present invention.

FIG. 17 is a structural diagram showing a sixth embodiment of the high-frequency heating device according to the present invention.

18 is a block diagram of a control device of the high frequency heating device shown in FIG.

19 is a flowchart showing a control method of the high frequency heating apparatus shown in FIG.

FIG. 20 is a graph showing an example of changes in the position of the movable stub and the magnetron temperature gradient.

FIG. 21 is a graph showing changes in magnetron temperature during normal operation with respect to elapsed heating time of the high-frequency heating device.

FIG. 22 is a graph showing a change in magnetron temperature when a moding occurs with respect to a heating elapsed time of the high frequency heating device.

23 is a flowchart showing another control method of the high-frequency heating device shown in FIG.

FIG. 24 is a graph showing a rate of change in magnetron temperature per unit time with a change in position of a movable stub during heating of two objects to be heated.

25 is a flowchart showing another control method of the high-frequency heating device shown in FIG.

FIG. 26 is a part of the flowchart shown in FIG. 25.

FIG. 27 is a structural diagram showing a seventh embodiment of the high-frequency heating device according to the present invention.

28 is a block diagram of a control device of the high-frequency heating device shown in FIG. 27.

FIG. 29 is a block diagram of another control device of the high frequency heating device shown in FIG. 27.

FIG. 30 is a structural diagram showing an eighth embodiment of the high-frequency heating device according to the present invention.

FIG. 31 is a configuration diagram showing a ninth embodiment of the high-frequency heating device according to the present invention.

FIG. 32 is a configuration diagram of a conventional high-frequency heating device.

FIG. 33 is an enlarged view of the movable stub shown in FIG. 32.

34 is a perspective view of the movable stub shown in FIG. 32. FIG.

FIG. 35 is a view for explaining the rotational position of the movable stub.

FIG. 36 is a block diagram of an inverter power supply device.

FIG. 37 is a side view of a magnetron driving transformer.

38 is a cross-sectional view taken along the line AA of FIG. 37.

FIG. 39 is a diagram showing a relationship between filament input current and magnetron input power.

FIG. 40 is a diagram in which the impedance on the heating chamber side when the object to be heated is placed on the outermost periphery of the turntable and the turntable is rotated is plotted on a Smith chart.

FIG. 41 is a diagram in which the impedance on the heating chamber side is plotted on a Smith chart when the object to be heated is placed on the outermost periphery of the turntable and the turntable is rotated to move the movable stub to avoid the moding. Is.

[Explanation of symbols]

 1 External Housing 2 Heating Chamber 3 Turntable 4 Center Shaft 5 Turntable Motor 6 Weight Sensor 7 Opening Cover 10 Magnetron 11 Magnetron Antenna 12 Waveguide 13 Movable Stub (Metal Reflector) 14 Rotating Shaft 15 Stub Motor 20 Control Circuit 30 Inverter Power supply device 40 Inverter control device 50 Detection winding output shaping circuit 60 Infrared sensing device 63 Radiant heat sensor 70 Control device 71-75 Relay M Heated object VM Half wave voltage doubler circuit

Claims (10)

[Claims] 1. A microwave generation means, a waveguide for guiding microwaves radiated from the microwave generation means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotation. A high frequency heating device comprising a metal reflector for impedance matching, which comprises a metal surface supported by a shaft and a metal stub provided on the periphery of the metal surface, and a control means for controlling the rotation of the metal reflector. A high-frequency heating device having a detection means for detecting a change in physical properties of an object to be heated during heating, and changing the microwave impedance matching in the heating chamber by operating the metal reflector before and after the change in physical properties. . 2. A microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotation. A high-frequency heating device comprising: a metal surface for supporting impedance; and a metal reflector for impedance matching, which has a metal stub provided on the periphery of the metal surface, and a control means for controlling rotation of the metal reflector. A high-frequency heating device characterized in that when the metal reflector rotates and passes through a position where the voltage standing wave ratio increases during heating, power supply to the microwave generation means is temporarily stopped or lowered. . 3. A microwave generating means, a waveguide for guiding the microwave radiated from the microwave generating means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotating. A high-frequency heating device comprising: a metal surface for supporting impedance; a metal reflector for impedance matching having a metal stub provided on the periphery of the metal surface; and a control means for controlling rotation of the metal reflector, wherein the metal It is characterized by rotating the reflector to create a state in which the microwave is hard to hit the object to be heated, and continuously supplying power to the microwave generating means without interruption to perform continuous operation with weak power. High frequency heating device. 4. A microwave generating means, a waveguide for guiding the microwave radiated from the microwave generating means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotating. A high-frequency heating apparatus comprising: an impedance matching metal reflector having a metal surface supported by a shaft and a metal stub provided on a peripheral portion of the metal surface; and a control means for controlling rotation of the metal reflector, wherein: When the detection means detects an oscillation abnormality of the microwave generation means, the control means rotates the metal reflector to perform microwave impedance matching in the heating chamber. A high-frequency heating device, characterized in that the abnormal oscillation of the microwave generation means is stopped by changing it. 5. A microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotation. A high-frequency heating apparatus comprising: an impedance matching metal reflector having a metal surface supported by a shaft and a metal stub provided on a peripheral portion of the metal surface; and a control means for controlling rotation of the metal reflector, wherein: The wave generation means has a storage means for storing the state of the heated object and the position of the metal reflector when the oscillation abnormality occurs, and the control means stores the memory when the heated object in the same state is heated again. A high-frequency heating device, wherein the position of the metal reflector is moved to a position avoiding the oscillation abnormality from the data stored in the means. 6. A microwave generating means, a waveguide for guiding microwaves radiated from the microwave generating means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotating. A high-frequency heating device comprising: an impedance matching metal reflector having a metal surface supported by a shaft and a metal stub provided on a peripheral portion of the metal surface; and a control means for controlling rotation of the metal reflector, wherein: Having a temperature detecting means in the outer contour of the wave generating means,
The temperature detection unit measures a temperature change per unit time of the microwave generation unit, and the control unit rotates the metal reflector according to the temperature change to change the microwave impedance matching in the heating chamber. Characteristic high-frequency heating device. 7. A first and second microwave generating means, and first and second waveguides for guiding the microwave radiated from the first and second microwave generating means to a heating chamber, The first waveguide includes means for measuring the shape of an object to be heated housed in the heating chamber, and control means for controlling the electric power supplied to the first and second microwave generation means. The tube has an opening at a position excellent in uniform heating property of the object to be heated, and the second waveguide has an opening at a position excellent in uniform heating property of the object to be heated. The high-frequency heating apparatus is characterized in that the means controls the power supply to the first and second microwave generation means according to the shape of the object to be heated. 8. The high-frequency heating apparatus according to claim 7, wherein the control means switches power supply to the first and second microwave generation means during heating in accordance with the shape of the object to be heated. Characteristic high-frequency heating device. 9. A microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotation. A high-frequency heating device comprising an impedance matching metal reflector having a metal surface supported on a shaft and a metal stub provided on the periphery of the metal surface, and a control means for controlling the rotation of the metal reflector. Having a height measuring means for measuring the height of an object, the height measuring means periodically measures the height of the object to be heated during microwave heating, and the object to be heated is covered with the object to be heated. A high-frequency heating device, characterized in that expansion of a thin film for food packaging for heating food by heating is detected to detect the finish of the object to be heated. 10. A microwave generation means, a waveguide for guiding the microwave radiated from the microwave generation means to a heating chamber, a dielectric rotating shaft inserted in the waveguide, and the dielectric rotation. In a high-frequency heating device comprising an impedance matching metal reflector having a metal surface supported by a shaft and a metal stub provided on the periphery of the metal surface, and a control means for controlling rotation of the metal reflector, When the object to be heated in the room has a sensor means for recognizing a state of being placed on the turntable, and the sensor means recognizes that the object to be heated is located in the vicinity of the outermost circumference on the turntable, the control is performed. The means controls the position of the metal reflector at a timing when the object to be heated passes in front of the opening of the waveguide that radiates microwaves, High-frequency heating apparatus, characterized in that to avoid the oscillation abnormality black wave generating means.