JPH0982468A - Microwave oven used also for induction heating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave oven equipped with dielectric heating func tion, which conducts sufficient heat from a heater to the material to be heated without being obstructed by parallel electrode plates of the induction heating in heating with the heater. SOLUTION: In heating with heater 3, an upper electrode plate 7a is moved to the uppermost position, wherein the plate 7a is furnished with a plurality of through punch holes 30 (in rows) in such an arrangement as parallel with the heater 3 and admitting through penetration of the heat from the heater. Thereby the heat is conducted from the heater directly to the material 11 to be heated through the holes 30.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microwave oven for meat and meat.
The present invention relates to a composite cooker equipped with a high-frequency heating device that thaws frozen foods (examples of frozen foods) such as fish by dielectric heating.

[0002]

2. Description of the Related Art Conventionally, when frozen food is thawed electrically,
In general, microwaves were thawed by microwave oven for small and thin ones, and objects for heating were sandwiched between parallel electrode plates and thawed by high frequency heating for large and thick ones.

It is a microwave oven (2.45).
This is because the radio waves of (GHz) cannot penetrate into the center of frozen food because of its short wavelength, and only thin foods can be thawed. On the other hand, the high frequency used for dielectric heating (13.56M
(Hz or 27.12 MHz) has a longer wavelength than microwaves, and thus has the advantage of being able to uniformly thaw inside the frozen food. A microwave oven incorporating this dielectric heating is disclosed in Japanese Patent Application Laid-Open No. 57-132694, but it was merely a description of the apparatus and function of microwave heating and dielectric heating.

Japanese Patent Publication No. 6-7012 discloses a microwave oven which uses a non-contact temperature sensor. However, this publication only describes a mechanism for accurately measuring the temperature of foods, and the dielectric heating method is used. No mention was made of specific examples of thawing and heating of foods applied to a combination type of microwave oven and microwave oven.

[0005]

However, although there have been proposals for combinations of microwave heating and dielectric heating, or heater heating and dielectric heating, all of these combinations are conceivable in actual products, and the heating chamber structure is It is difficult and causes the following various problems. First, a high-performance microwave oven is equipped with a heater for oven and grill, which is usually placed on the top surface. Therefore, when the heater is heated, the parallel electrode plate for dielectric heating enters between the heater and the object to be heated to prevent the heater heating.

During dielectric heating, an object to be heated is placed between the parallel electrode plates. On the other hand, at the time of microwave heating, a turntable on which an object to be heated is placed is required, and at this time, a parallel electrode plate for dielectric heating is unnecessary (obstruction).

Next, when performing microwave heating thawing or dielectric heating thawing, microwave heating thawing has the drawbacks that only the surface is thawed and the surface temperature rises too much, and microwave irradiation unevenness occurs. In addition, there is a drawback in that it is necessary to re-match the impedance with the load because the value of the dielectric loss of the object to be heated changes as the thawing progresses. Therefore,
It was necessary to accurately measure the surface temperature of the object to be heated and improve the finishing accuracy by using both microwave heating and dielectric heating.

The present invention has been made in view of the above-mentioned problems of the prior art. In the dielectric heating, when the heater is heated, the parallel electrode plate for dielectric heating does not get in the way and the heater heat can be sufficiently transmitted to the object to be heated. It is a first object to provide a microwave oven with heating. A second object is to provide a microwave oven for combined use with dielectric heating in which the lower electrode plate for dielectric heating does not interfere during microwave heating. Further, a third object is to provide a microwave oven combined with dielectric heating, which is capable of thawing a frozen material to be heated with good finish by dielectric heating and microwave heating.

[0009]

The present invention has the following constitution in order to solve the above problems. In order to solve the first problem, the invention of claim 1 provides a heating chamber provided in the main body, a microwave generation unit for radiating microwaves into the heating chamber, a heating unit by a heater, and the heating unit. In a microwave oven combined with dielectric heating, which comprises a parallel electrode plate for inductively heating a dielectric material as an object to be heated in the room, and a high frequency generating means for performing power amplification for applying a high frequency to the parallel electrode plate, each of the parallel electrode plates is It is made of a conductive material that is insulated from the heating chamber, and the lower part is the fixed electrode plate and the upper part is the movable electrode plate.
The heater shall be heated from the top surface above the upper electrode plate.The upper electrode plate shall be provided with a plurality of through holes so that the heater heat can sufficiently pass through.When heating the heater, the upper electrode plate should be placed at the uppermost position. It has a structure of a microwave oven combined with dielectric heating, which is characterized in that it moves.

According to a second aspect of the present invention, in order to solve the second problem, when a microwave is heated, a motor rotates a turntable table on which the object is placed so that the object is uniformly irradiated with the microwave. Wherein the turntable motor is stopped at the time of dielectric heating to fix the turntable and the turntable is used as a lower electrode plate for dielectric heating. 1. The microwave oven with dielectric heating described in 1.

In order to solve the first problem, the invention of claim 3 includes a heating chamber provided in the main body, a microwave generating means for radiating a microwave into the heating chamber, and a heating means by a heater. In the microwave oven combined with dielectric heating, the heating chamber comprises a parallel electrode plate for dielectrically heating a dielectric to be heated in the heating chamber, and a high frequency generator for amplifying power for applying a high frequency to the parallel electrode plate. It has a heater moving means having a rotating mechanism on its side surface, and a means for moving the dielectric heating upper electrode plate to the uppermost position when the heater is heated. The heater movable means moves the heater to the top surface side to perform heater heating, which is a microwave oven with dielectric heating.

In order to solve the third problem, a fourth aspect of the present invention provides a heating chamber provided in the main body, a microwave generating means for radiating a microwave into the heating chamber, and a heating chamber provided in the heating chamber. A heating chamber of a microwave oven with dielectric heating, comprising a parallel electrode plate for dielectrically heating a dielectric as a heating object, and a high frequency generating means for amplifying power by applying high frequency to the parallel electrode plate. Is provided with a non-contact temperature sensor for detecting the surface temperature of the object to be heated, and when defrosting a frozen product such as frozen food, the temperature of the frozen product to be defrosted detected by the non-contact temperature sensor is the first. Until the temperature of the frozen product is thawed by microwaves and the frozen product is frozen by dielectric heating until the temperature of the frozen product exceeds the first predetermined temperature and reaches the second predetermined temperature. Thaw things Having a dielectric heating combined microwave oven structure, characterized in that it has a freezing material decompression means.

According to a fifth aspect of the invention, the frozen food defrosting means comprises:
5. The microwave oven with dielectric heating according to claim 4, wherein the microwave thawing and the dielectric heating thawing are alternately performed at least a plurality of times based on the information of the non-contact temperature sensor. The parallel electrode plate for dielectric heating of claims 4 and 5 may be provided with an attaching / detaching means.

Here, the heater is usually mounted on the top surface, and the upper electrode plate for dielectric heating enters between the heater and the object to be heated during heating of the heater to hinder the heating of the heater. Further, the upper electrode plate is movable up and down for impedance matching with the load as the dielectric loss of the object to be heated changes during thawing. The upper electrode plate is moved to the uppermost position, and the upper electrode plate is provided with a plurality of holes (for example, a plurality of rows) penetrating the upper electrode plate in parallel with the heater by punching or the like through which the heater heat can sufficiently pass, so that the heater heat is not heated. Allows for direct heat transfer to the object.

As an alternative to this, as in the third aspect of the invention, the heater is not fixed to the top surface, but heater movable means having a rotation mechanism such as a crank mechanism is provided on the side surface of the heating chamber to heat the heater. Can move the upper electrode plate to the uppermost position, and then move the heater to the top surface by the heater moving means having a rotating mechanism to heat the heater.

Regarding the lower electrode plate for dielectric heating,
Since it is unnecessary during microwave heating, it is desirable that this lower electrode plate can be used as a microwave heating turntable. In view of this, in the invention of claim 2, this rotary turntable is fixed to the lower electrode plate for use without energizing the rotary motor during dielectric heating.

Next, according to claims 4 and 5, when the frozen food is actually heated and thawed, the temperature of the thawed object to be heated is usually measured by using some means to control the heating.
In the present invention, for example, a non-contact temperature sensor of infrared absorption type and its temperature detection circuit are provided, and microwave heating and dielectric heating are used together based on the detected temperature, so that heating and thawing with good finish accuracy can be performed in a short time. is there.

That is, in the case of considering a microwave oven used for household use together with dielectric heating, there is a relation between the microwave output and the dielectric heating output, that is, microwave output> dielectric heating output. On the other hand, as described above, the microwave heating has uneven irradiation, and there is a temperature difference of 5 ° C. or more in the surface temperature of the thawed material to be heated (frozen material thawed by heating). Further, it is known that the value of the dielectric loss of the object to be heated and thawed changes during the thawing in the dielectric heat thawing, and the output decreases unless impedance matching with the load is taken.

Therefore, in the inventions of claims 4 and 5, the surface temperature of the frozen material to be heated is obtained by using the microwave heating thawing and the dielectric heating thawing together while measuring the surface temperature of the heated thawing material. The difference can be suppressed within 3 ° C, and thawing with good finishing accuracy can be realized.

Conventionally, there was an application for a combination of microwave heating and dielectric heating, or combination of heater heating and dielectric heating, but in actual products, all these combinations are conceivable, and the heating chamber structure was difficult. In the present invention,
It shows the solution and suggests that the heating and thawing accuracy higher than ever can be obtained.

As means for detecting the end of thawing, there are direct measurement of the surface temperature with a non-contact temperature sensor and indirect measurement with detection of water vapor emitted from the object to be heated. The non-contact temperature sensor detects the surface temperature. It is a thing.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. The structure of the microwave oven with dielectric heating of the present invention is shown in FIG. 1 ((a): perspective view, (b): front view).
It is like.

As shown in FIG. 1, a heating chamber 2 is provided inside the main body 1.
On the top surface 2a of the heating chamber 2, there are bar-shaped ovens at the points 2a1 and 2a1 which are recessed upward in a mountain shape.
The heaters 3 and 3 for grills are inserted and equipped. Also,
A power supply port 4 is formed on a side surface (right side surface in FIG. 2) of the heating chamber 2, and microwaves generated by a microwave generator 5 are supplied from the power supply port 4 via a waveguide 6 to the heating chamber 2. It is radiated to 2. Although the above-mentioned structure is the structure of a conventional microwave oven, in the embodiment of the present invention, the heating chamber 2 is a metal housing which is reliably grounded, and the parallel electrode plates 7a and 7b are provided in the heating chamber 2. Equip.

Here, the upper electrode plate 7a is of an electrically movable type using an unillustrated motor or the like (guide member 7a).
1, the upper electrode plate moves up and down in parallel, and the lower electrode plate 7b is a fixed type shared with the microwave heating turntable 7b. The electrode plates 7a and 7b are high-frequency generators 8
And is made of a conductive material that is insulated from the heating chamber 2. Here, the electrode plates 7a and 7b include the electrode plate 7
A protective material 9 made of non-metal and having a small dielectric loss (small tan δ) is attached for the purpose of protecting the surfaces of a and 7b.

Since the lower electrode plate 7b is also used as the turntable 7b at the time of microwave heating, it is equipped with a motor control device 10 for rotation. It is used as a fixed electrode plate by stopping the motor energization at the time of dielectric heating. The heating object 11 is mounted on the protective material 9. When performing heating control, the surface temperature of the object to be heated 11 is measured by an infrared absorption type non-contact temperature sensor 12 and input to a control circuit 13, and this control circuit 13 performs combined control of microwave heating and dielectric heating. Has been done.

Next, as shown in FIG. 2, the circuit configuration of the embodiment of the present invention is divided into a microwave generator circuit 17 and a dielectric heating high-frequency generator circuit 18 from a commercial power source 15 via a switch 16. Further, the heater 3 for heating is connected in parallel with the switch 16 from the commercial power source 15 and its output is adjusted by a triac 19 or the like. The microwave generation circuit 17 non-smoothly rectifies the AC power source that has passed through the switching device 16 by the rectification circuit 20 and applies it to the step-up transformer 21. Then, the high voltage is applied to the magnetron 22 to generate microwaves.
Various well-known circuits can be set for the other transistors and capacitors, and therefore description thereof is omitted.

The induction heating high-frequency generation circuit 18 applies the AC power supplied from the switch 16 to the high-frequency power supply circuit 24 via the DC circuit 23. The high-frequency power supply circuit 24 power-amplifies the applied AC power supply by a high-frequency oscillation circuit and a semiconductor device for signal amplification, and applies it to a high-frequency transformer 25. The high frequency transformer 25 and the resonance circuit section including parallel electrode plates 7a and 7b in parallel with the variable capacitor 26, the resonance coil 27, and the object to be heated (the frozen object to be thawed) 11 are sandwiched between the high frequency transformer 25 and the high frequency transformer 25. The impedance of the resonance circuit unit and the high frequency power supply circuit 24 are matched by switching the transformer 25 by tapping.

In such a microwave oven combined with dielectric heating, when the heater is heated, the heater 3 and the object 11 to be heated on the top surface are heated.
There is a problem that the heat of the heater 3 is not efficiently transferred to the article to be heated 11 because the dielectric heating upper electrode plate 7a is provided between the two. As a means for solving this, the upper electrode plate 7
It is conceivable that a is attached and detached, but the mechanism becomes complicated. Therefore, in the embodiment of the present invention, as shown in FIG. 1, a plurality of (plural rows) punching holes 30 parallel to the heater 3 are provided in the upper electrode plate 7a so as to penetrate from the front surface to the back surface (from the upper surface to the lower surface). When heating the heater 3, the upper electrode plate 7a is moved to the uppermost position. By doing so, the heat of the heater 3 reaches the object to be heated 11 through the punching holes 30 of the upper electrode plate 7a, so that the heat of the heater can be efficiently transferred to the object to be heated 11. (Embodiment corresponding to billing contract 1)

Next, during microwave heating, the table (turntable 7b) on which the object 11 to be heated is placed is rotated so that the object 11 to be heated is uniformly irradiated with microwaves.
The lower electrode plate 7b is required during dielectric heating, and the positional relationship with the turntable 7b is difficult. In this case, it is conceivable that the lower electrode plate 7b is of a detachable type, but like the upper electrode plate 7a, the mechanism becomes complicated. Therefore, in this embodiment, the difficulty of the positional relationship is solved by sharing the turntable 7b and the lower electrode plate 7b. That is, the rotation motor of the turntable 7b is provided with the control device 10 for ON / OFF control, the rotation motor of the turntable 7b is de-energized during dielectric heating, and the fixed turntable 7b is used as the lower electrode plate 7b. To use. (Embodiment corresponding to claim 2)

In the microwave oven with dielectric heating provided with the upper and lower electrode plates 7a and 7b as described above, in the embodiment corresponding to claim 1, the heater is not fixed on the top surface but as shown in FIG. A heater moving means 14 having a rotating mechanism 14a is provided on the side surface (left side surface facing) of the heating chamber 2, and the upper electrode plate 7a is moved to the uppermost position at the time of heating with the flat plate heater 14b, and then, The movable heater 14b may be rotated upward by the rotating mechanism 14a and moved to the vicinity of the top surface 2a. (Embodiment corresponding to claim 3)

In the above microwave oven combined with dielectric heating, when a food to be thawed to be heated, which is frozen food, is thawed, the object to be heated (frozen food to be thawed:
Here, it is desirable to perform the thawing control while detecting the surface temperature of the object to be thawed 11). An infrared absorption type non-contact temperature sensor 12 is used as a means for detecting the surface temperature of the heated thawed material 11. There are various methods such as a pyroelectric sensor, a thin film thermistor, and a thermopile, which can be determined depending on accuracy, reliability, price and the like.

By the way, generally, in microwave heating and dielectric heating, if the size of the heating chamber 2 is the same as that of a microwave oven,
The output has a relationship of microwave output> dielectric heating output. On the other hand, when thawing by dielectric heating, the high frequency used for it is 13.56 MHz or 27.12 MHz.
Since the wavelength is longer than the microwave of 2.45 GHz, the inside of the object to be heated 11 can be uniformly thawed. Therefore, by taking advantage of these two advantages, thawing is performed using both microwave heating and dielectric heating. (Embodiments corresponding to claims 4 and 5)

Specifically, as shown in FIG. 2, a switching device 16 between a microwave generator 17 and a high frequency generator 18 is provided, and microwave heating and thawing with a large output is performed in the initial stage of thawing, and then thawing unevenness is generated. Performs dielectric heating and thawing that enables a highly accurate finish that is suppressed. This switching can be controlled by the temperature of the object to be heated and thawed 11 measured by the non-contact temperature sensor 12, and may be performed, for example, at -5 ° C (an example of the first predetermined temperature). Naturally, various controls are possible depending on the material and amount of food. After that, when the target temperature (for example, 0 ° C .: an example of the second predetermined temperature) is reached, the dielectric heating thawing is stopped and the thawing is completed.

Here, by performing microwave thawing and dielectric heating thawing alternately a plurality of times for thawing, it is possible to perform heat thawing with a more accurate finish. This will be explained based on the graph. If the defrosting is first performed by microwave heating as shown in FIGS. 3 and 4, the above (microwave output> dielectric heating output)
From the above, when the microwave is heated, the temperature increase rate of the surface temperature of the food that is the thawed material 11 to be heated is high, but the surface temperature unevenness is large.

Therefore, dielectric heating is switched within a range (for example, 10 ° C.) in which the surface temperature unevenness does not become too large, to promote the thawing of the frozen food and suppress the surface temperature unevenness. Then, dielectric heating and thawing are performed for a certain period of time, and microwave heating and thawing are switched. In this way, microwave heating and dielectric heating are repeated so as not to impair the quality of the food, and if the surface temperature of the frozen food finally reaches -5 ° C, control is performed so that the product is finished only by dielectric heating thereafter. High quality thawing is possible.

[0036]

From the above description, the present invention has the following effects. According to the invention of claim 1, even in a microwave oven that also uses dielectric heating, when the heater is heated, even if the parallel electrode for dielectric heating enters between the heater and the heating object, the heating of the heater is hindered. Never. Further, according to the invention of claim 2, the lower electrode plate for dielectric heating can be shared with the turntable for microwave heating even if it is unnecessary during microwave heating, and it does not interfere. The utilization rate of parts is high. According to the third aspect of the invention, the heater moving means is provided instead of fixing the heater to the top surface, the upper electrode plate is moved to the uppermost position when the heater is heated, and then the crank mechanism is provided. Since the movable heater can be moved to the top surface to heat the heater, the heating of the heater is not hindered. Further, claim 4 and claim 5
According to the invention, the defrosting can be performed with high finishing accuracy. According to the present invention, (1) in the conventional microwave thawing process, the variation in the surface temperature of the finished food product was about 8 ° C.
By using a microwave oven combined with dielectric heating, compared to only microwave heating, there is no significant increase in time, and the variation in food surface temperature at the time of finishing is about 3 ° C., enabling high-quality thawing. (2) Since the high frequency used for dielectric heating has a much longer wavelength than microwaves, the penetration length of the high frequency is large,
It is also possible to thaw large-volume foods such as so-called block meat. Also has the effect.

[Brief description of drawings]

FIG. 1 is an explanatory view of a microwave oven with combined dielectric heating according to an embodiment of the present invention, in which (a) is a sketch and (b) is a front view.

FIG. 2 is a circuit configuration diagram and a block diagram according to an embodiment of the present invention.

FIG. 3 is an explanatory view of a heating state of an object to be heated when frozen food is thawed by using microwave and dielectric heating in combination, and is a graph example of heating time-food surface temperature.

FIG. 4 is an explanatory diagram of a heating state of the object to be heated, which is an example of a graph of heating time-food surface temperature unevenness.

[Explanation of symbols]

 1 Main Body 2 Heating Chamber 2a Top Surface 3 Heater 4 Feed Port 5 Microwave Generator 6 Waveguide 7a, 7b Upper Electrode Plate, Lower Electrode Plate 8 High Frequency Generator 10 Rotation Motor Control Device 11 Heated Object 12 Non-contact Temperature Sensor 13 Control circuit 14 Heater moving means 15 Commercial power supply 16 Switcher 17 Microwave generation circuit 18 High frequency generation circuit for dielectric heating 20 Rectifier circuit 21 Boosting 22 Magnetron 30 Punching hole

Claims (5)

[Claims] 1. A heating chamber provided inside the main body, a microwave generating unit for radiating microwaves into the heating chamber, a heating unit by a heater, and a dielectric as a material to be heated is dielectrically heated in the heating chamber. In the microwave oven combined with dielectric heating, which comprises a parallel electrode plate and a high frequency generating means for performing power amplification by applying a high frequency to the parallel electrode plate, the parallel electrode plates are each made of a conductive material insulated from a heating chamber, In addition, the lower part is a fixed electrode plate, the upper part is a movable electrode plate, the heater is to heat from the top surface above the upper electrode plate, and the upper electrode plate has a plurality of holes through which the heater heat can sufficiently pass. A microwave oven with dielectric heating, which is provided with the upper electrode plate moved to the uppermost position when the heater is heated. 2. A turntable base on which an object to be heated is placed by a motor so that the object to be heated is uniformly irradiated with microwaves during microwave heating, and the turntable is rotated during dielectric heating. 2. The microwave oven with dielectric heating according to claim 1, wherein the rotation of the motor is stopped, the turntable is fixed, and the turntable is used as a lower electrode plate for dielectric heating. 3. A heating chamber provided inside the main body, a microwave generating means for radiating microwaves into the heating chamber, a heating means by a heater, and a dielectric material, which is an object to be heated, is dielectrically heated in the heating chamber. In the microwave oven combined with dielectric heating, which includes a parallel electrode plate and a high frequency generating means for performing power amplification for applying a high frequency to the parallel electrode plate, a heater moving means having a rotating mechanism on the side surface of the heating chamber,
And a means for moving the upper electrode plate for dielectric heating to the uppermost position when heating the heater, and after moving the upper electrode plate for dielectric heating,
A microwave oven combined with dielectric heating, wherein the heater is moved to the top surface side by heater moving means having the rotating mechanism to perform heater heating. 4. A heating chamber provided inside the main body, a microwave generating means for radiating a microwave into the heating chamber, and a parallel electrode plate for dielectrically heating a dielectric to be heated in the heating chamber. In a microwave oven combined with dielectric heating, which is equipped with a high frequency generator for amplifying power by applying a high frequency to the parallel electrode plate, a non-contact temperature sensor for detecting the surface temperature of an object to be heated in a heating chamber of the microwave combined with dielectric heating. When the frozen product such as frozen food is thawed, the frozen product is thawed by microwave until the temperature of the frozen product to be thawed detected by the non-contact temperature sensor reaches a first predetermined temperature. And a frozen product thawing means for thawing the frozen product by dielectric heating until the temperature of the frozen product exceeds the first predetermined temperature and reaches the second predetermined temperature. Dielectric heating Use a microwave oven. 5. The frozen food thawing means performs microwave thawing and dielectric heat thawing based on information from the non-contact temperature sensor.
The microwave oven with combined dielectric heating according to claim 4, wherein the microwave oven is alternately thawed at least a plurality of times.