JPH08124672A - High frequency heating device - Google Patents

Abstract

PURPOSE: To uniformly heat a part to be heated on the whole by switching an opening easily passing electromagnetic wave and an opening hardly passing of a plurality of openings by the rotation of a rotating body so that the electric fields apparently generated from various feed points can be frequently switched. CONSTITUTION: An electromagnetic wave emitted from a magnetron 1 heats a food 5 on a turn table 4 within a heating chamber 3 through a waveguide 2. A plurality of opening parts 6 for guiding the electromagnetic wave from the waveguide 2 to the heating chamber 3 are covered with a transparent opening cover 7 consisting of a material with low loss which hardly absorb the electromagnetic wave. A metallic stirrer blade 8 is provided as a rotating body within the waveguide 2, and rotated by a stepping motor 9. Since the blade 8 has various operating patterns according to purposes, the moving distance from a standard point is regularly monitored by a blade position detector 10. A control part 11 switches the openings by the oration of the rotating body so that electric fields apparently generated from various feed points can be frequently switched.

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 device for heating an object to be heated, such as food, for supplying electric power (how to put electromagnetic waves into a heating chamber), and particularly to make the heating distribution uniform and improve the heating efficiency. It is related to the configuration.

[0002]

2. Description of the Related Art A microwave oven, which is a typical high-frequency heating device, has conventionally been constructed as shown in FIGS.

The microwave oven shown in FIG. 11 has a general structure using a turntable 4. Here, the electromagnetic wave emitted from the magnetron 1 as the electromagnetic wave radiating section is transmitted through the waveguide 2 and distributed in the heating chamber 3 as a standing wave determined by the shape of the heating chamber 3 and the position of the opening 6. The food 5 generates heat according to the electric field component of the standing wave and the dielectric loss of the food 5. The electric power P [W / m ³ ] absorbed per unit volume of food is determined by the strength E [V / m] of the applied electric field, the frequency f [Hz], and the relative permittivity εr and dielectric loss tangent tan δ of the food ( Number 1)
It is expressed as Since the heating distribution of the food 5 is generally determined by the standing wave distribution of the electromagnetic wave, in order to suppress the unevenness of the heating distribution, the turntable 4 of the table on which the food is placed is rotated to make the heating distribution on the concentric circles uniform. ing.

[0004]

[Equation 1]

Further, as another means for uniformization, the heating chamber 3
There was also a stirrer method in which electromagnetic waves are agitated by constant rotation of a metal plate in the inside, and a rotating waveguide method in which the opening 6 itself of the waveguide 2 is constantly rotated, but the turntable type is the most common. It has been commercialized.

[0006] Further, there are some which aim at making them uniform by having a plurality of openings 6, and Fig. 12 shows a type in which two openings 6 are provided on the wall surface of the heating chamber 3 (Japanese Patent Laid-Open No. 4-3192).
No. 87).

Further, as shown in FIG. 13, there is also a case in which the end face 27 of the sub-waveguide 26 is moved at a position facing the plurality of openings 6 to switch the openings 6 which are likely to emit electromagnetic waves so as to be uniform. (JP-A-5-74566).

On the other hand, many means for increasing heating efficiency have been studied. First, as shown in FIG. 14, a stub element 28 which can project inside the waveguide 2 is provided.
Is configured so that its position can be adjusted by driving the stub movable mechanism 29 by the drive motor 31 via the movable cam 30, and the stub element 28 is moved according to cooking to see the heating chamber 3 from the magnetron 1 in an aligned state ( There is one that always keeps the easiness of transmission of electromagnetic waves good (Japanese Patent Laid-Open No. 5-283).
No. 160).

When food is placed on the peripheral surface of the turntable 4, the rotation of the turntable 4 causes the food 5 to be temporarily stopped at the position closest to the opening 6 or slow down the rotation speed ( Japanese Utility Model Publication No. 4-30800).

Further, there is one in which the rotation speed of the turntable 4 is changed according to the type of heating such as a microwave or a heater (Japanese Utility Model Laid-Open No. 4-125105).

[0011]

However, in the above-mentioned conventional configuration, when the electromagnetic wave is introduced into the heating chamber 3 by connecting the waveguide 2 and the heating chamber 3, the heating distribution is uniform for each material and shape of the food 5. However, there is a problem that it is not possible to uniformly heat all the foods 5 with one opening 6 because the appropriate positions of the openings 6 are different.

At this time, if the turntable 4 is used, the heating distribution on the concentric circles can be made uniform. However, no matter how much the turntable 4 is rotated, the radial distribution and the vertical distribution seen from the center of rotation are Not improved.

Further, even when a plurality of openings 6 are provided, it is difficult to make the heating distribution of all foods 5 uniform by only opening the openings 6 at the same time, and it is difficult to make the heating distribution uniform. 11 microwave oven and FIG.
There is no big difference in the heating distribution of the microwave oven. After all, unless the opening 6 is changed appropriately for each food, the finished state cannot be satisfied by the user.

Therefore, as shown in FIG. 13, there is a method in which the end face 27 of the sub-waveguide 26 is moved at a position opposed to the plurality of openings 6 to switch the openings 6 which apparently tend to emit electromagnetic waves. It is effective for homogenization of. However, considering an actual configuration, a space occupied by a plurality of sub-waveguides 26 and a space for a shield configuration that prevents leakage of electromagnetic waves when moving the end face 27 of the sub-waveguide 26 are required.
Therefore, whether the size of the entire microwave oven increases,
Alternatively, there is a problem that the effective volume inside the heating chamber 3 becomes smaller than the entire size. If the size of the whole is large, the user will have difficulty in placing it, and if the effective volume is small, the user will be dissatisfied with the fact that only small food 5 can be put therein. Similarly, the microwave oven becomes heavy, which causes a problem that it is difficult to carry. In addition, operating the sub-waveguide 26 including the shield structure may consume considerable power.

For stirrers and rotating waveguides that stir electromagnetic waves, it is possible to make the heating distribution uniform in a menu such as thawing and cooking where it is desired to avoid electromagnetic wave concentration as much as possible. However, the alignment state changes continuously due to constant rotation, and it is difficult to maintain a good alignment state at all times, and there is a problem that the efficiency decreases. If the efficiency is lowered, the heating time becomes long, the waiting time of the user becomes long, the power is wasted, and the thermal stress of the magnetron 1 increases, so that the reliability is deteriorated.

On the other hand, as a means for increasing the heating efficiency, it is an effective means to always maintain a good alignment state for each cooking as shown in FIG. However, in addition to the configuration for distribution, the stub element 28, the stub movable mechanism 29, the movable cam 3
0 and another component such as the drive motor 31 are required, and when a rotating mechanism such as a stirrer, a rotary waveguide, and a turntable 4 is used, complicated control according to the operation is required. Therefore, the structure is complicated and the cost is increased. Generally, stirrers, rotating waveguides, turntables 4
In order to make the heating distribution uniform by such a rotating mechanism as described above, considering that power is required for rotation and the matching state cannot always be kept constant, it can be said that efficiency is naturally limited.

As another means, the turntable 4
With regard to the means for temporarily stopping the food 5 at the position closest to the opening 6 or slowing the rotation speed by the rotation of the above, the efficiency when the food 5 is placed in the center of the turntable 4 cannot be improved.

Further, as another means, there is a means for changing the rotation speed of the turntable 4 according to the kind of heating, but it is not shown what to do concretely.

The present invention is intended to solve the above problems, and it is an object of the present invention to realize a high-frequency heating apparatus with a uniform heating distribution of an object to be heated and a good heating efficiency.

[0020]

In order to achieve the above object, the high frequency heating apparatus of the present invention has the following constitution.

That is, a heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating part for radiating an electromagnetic wave, and a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating part into the heating chamber through a plurality of openings. A configuration is provided that includes a rotating body that operates in the waveguide and is made of a conductive member, and a control unit that controls emission of electromagnetic waves from the electromagnetic wave emitting unit and operation of the rotating body.

Also, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave emission part for emitting an electromagnetic wave; a waveguide for guiding the electromagnetic wave emitted from the electromagnetic wave emission part into the heating chamber through an opening; and one or a plurality of operation patterns in the waveguide. A rotating body made of a conductive member, an operation key for inputting the type of the object to be heated, the size of the heating output by the electromagnetic wave, the setting of the heating time, etc. And a control unit that controls the operation of the rotating body.

Also, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave radiating part for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating part into the heating chamber through an opening, and a conductive member in the waveguide having a plurality of operation patterns. And a detection unit for detecting at least one of the physical quantity of the object to be heated or the state of the heating chamber and its change, and the emission of electromagnetic waves from the electromagnetic wave emission unit according to the output of the detection unit. The control unit controls the operation of the rotating body.

Further, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave radiating part for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating part into the heating chamber through an opening, and a conductive member in the waveguide having a plurality of operation patterns. And a control unit that controls the operation of the rotating body and the emission of electromagnetic waves from the electromagnetic wave emitting unit, and when using frozen food as the object to be heated, the rotating body is configured to rotate. And

Further, a heating chamber for loading and unloading the object to be heated,
A food placing table on which the object to be heated is rotated in the heating chamber, an electromagnetic wave radiating unit that radiates an electromagnetic wave, and a waveguide that guides the electromagnetic wave radiated from the electromagnetic wave radiating unit into the heating chamber through an opening. An operation key for inputting the type of the object to be heated, the size of the heating output by the electromagnetic wave, the setting of the heating time, etc. A control unit for controlling the rotation operation is provided, and when the milk or the soup is input by the operation key, the food placing table is controlled so as not to rotate.

Further, a heating chamber for loading and unloading an object to be heated, a food placing table on which the object to be heated is placed and rotated, an electromagnetic wave radiating section for radiating an electromagnetic wave, and an electromagnetic wave radiated from the electromagnetic wave radiating section. A waveguide that guides into the heating chamber through an opening, a detection unit that detects at least one of the physical quantity of the object to be heated or the state inside the heating chamber and its change, and the output of the detection unit. And a control unit that controls the radiation operation of the electromagnetic wave from the electromagnetic wave radiation unit and the rotation operation of the food placing table, and rotates the food placing table when the object to be heated is determined to be liquid by the detecting unit. The configuration is such that it is controlled so as not to allow it.

Further, the rotating body is formed in a plate shape, a rod shape, or a blade shape.

[0028]

The present invention has the following functions due to the above construction.

That is, since the rotating body made of a conductive member operates in the waveguide while having a plurality of openings,
The apparent opening can be switched depending on the position of the rotating body.

Further, since the rotating body made of a conductive member in the waveguide operates in a plurality of operation patterns according to the input of the operation key by the user, the kind of the object to be heated, the size of the heating output by the electromagnetic wave, A heating distribution can be generated according to the setting of the heating time.

Further, since the rotating body made of a conductive member in the waveguide operates in a plurality of operation patterns in accordance with the detection output of the detecting section, it depends on the physical quantity of the object to be heated, the state in the heating chamber and its change. It is possible to cause a heating distribution.

Further, when a frozen food is used as the object to be heated, the rotating body made of a conductive member in the waveguide rotates, so that the electromagnetic waves are constantly agitated and partial concentration does not occur.

Further, since the food placing table is not rotated when the user inputs milk or soup with the operation keys,
The matching state is constant, and the electric power required for rotating the food placing table is not consumed.

Furthermore, since the food placing table is not rotated when the object to be heated is determined to be liquid by the detecting section, the alignment state is constant and the power required for rotating the food placing table is not consumed.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a high frequency heating apparatus according to an embodiment of the present invention. The electromagnetic wave emitted from the magnetron 1 as the electromagnetic wave radiating part heats the food 5 on the turntable 4 in the heating chamber 3 via the waveguide 2. At this time, the plurality of openings 6 that guide the electromagnetic waves from the waveguide 2 into the heating chamber 3 are covered with a transparent opening cover 7 made of a low-loss material that hardly absorbs the electromagnetic waves. Further, a metallic stirrer blade 8 as a rotating body is provided in the waveguide 2, which is rotationally driven by a stepping motor 9. Since the stirrer blade 8 has various operation patterns according to the purpose, the blade position detector 10 constantly monitors the moving distance from the reference point. The control unit 11 includes a signal from the operation panel 12 keyed by the user and a weight detector 13
Alternatively, based on the signal from the other state detector 14 and the signal from the blade position detector 10, the emission of electromagnetic waves from the magnetron 1 is controlled, and the operation pattern of the stirrer blade 8 is determined to determine the stepping motor 9. The drive is controlled, and the drive of the motor 15 is controlled by determining the rotation or stop of the turntable 4. And body cover 1
6. It has a door 17 that can be opened and closed.

Here, depending on the position of the stirrer blade 8,
Among the plurality of openings 6, the opening that emits electromagnetic waves easily and the opening that does not easily emit electromagnetic waves can be switched to switch the heating distribution, and at the same time, the matching state can be switched. In particular, since the position and the rotating operation of the stirrer blade 8 can be freely set in accordance with the signal from the operation panel 12 and the signal from the weight detector 13 or the other state detector 14, it is suitable for the purpose of heating. Can be distributed and matched. further,
Since the rotation and stop of the turntable 4 can be freely set, depending on the food 5, the turntable 4 can be rotated to make the food 5 uniform in the concentric direction as viewed from the center of rotation, or the food 5 can be milk or juice (liquid). In the case of (shaped), the turntable 4 can be stopped to improve the alignment.

FIG. 2 is a sectional view taken along the line AA 'of FIG. The width of the waveguide 2 is widened midway, and the stirrer blade 8 is formed inside. Further, since the opening cover 7 is transparent, the user can see the operation of the stirrer blade 8 through the five openings 6 and the openings 6.

FIG. 3 and FIG. 4 are sectional structural views of a high frequency heating apparatus according to another embodiment of the present invention.

FIG. 3 shows the opening 6 only in front of the stirrer blade 8.
4 shows the case where there is only one opening 6 in front of the stirrer blade 8.

Although not shown, depending on the shape of the heating chamber 3 and the height of the turntable 4, the opening 6 may be provided at a position farther from the stirrer blade 8 as viewed from the magnetron 1, or the waveguide. The longitudinal direction of 2 may be configured in the vertical direction or the diagonal direction, or the waveguide 2 may extend from the magnetron 1 not only in one direction but in a plurality of directions to form a plurality of openings 6, or only by the back surface of the heating chamber. It is also conceivable to fold the waveguide 2 so as to straddle the side surface, the bottom surface, the top surface, or two or three surfaces thereof. Further, the stirrer blade 8 may be configured of not only four blades but also another number of blades, and the rotating body may be not only blade-shaped but also plate-shaped or rod-shaped.

FIG. 5 is a schematic view of the main part of the high-frequency heating apparatus according to the embodiment of the present invention, showing the operation panel 12.

First, when the user warms the milk, the milk is put in the heating chamber 3 and then the milk key 18 is pressed.
Press the start key 19. Then, the control unit 11 determines that the food 5 is milk based on the signal from the operation panel 12, determines various states such as the amount, shape and temperature of milk based on the signals from the weight detector 13 and the state detector 14, The position of the stirrer blade 8 is determined, the stepping motor 9 is driven based on the signal from the blade position detector 10, and before and after that,
Radiation of electromagnetic waves from the magnetron 1 is started. At this time, the turntable 4 is kept stationary to stabilize the alignment state and heat efficiently. After that, the weight detector 13 or the state detector 14 heats for a predetermined time, or the heating ends when the milk reaches an appropriate temperature. In the case of milk, if an electric field is concentrated on the bottom surface, convection will naturally produce a good distribution, and heating can be performed in a stable and appropriate matching state, thus improving efficiency.

On the other hand, when the user thaws the frozen food of meat or fish, the food 5 is put in the heating chamber 3 and then the thaw key 20 is used.
Then, press the start key 19. Then, the control unit 11
Uses the signal from the operation panel 12 to determine the food 5 as frozen food, and the signals from the weight detector 13 and the state detector 14 to determine various states such as the amount, shape and temperature of the frozen food, and an appropriate stirrer. The number of rotations of the blade 8 is determined, the stepping motor 9 is driven to rotate, and the electromagnetic wave emission from the magnetron 1 is started before and after that. At this time, the turntable 4 is also rotated together with the stirrer blades 8 to avoid local concentration of the electric field as much as possible. Thereafter, the heating is finished for a time determined by the weight detector 13 or the state detector 14, or the heating is terminated when the temperature reaches a proper temperature (thaw is completed). In the case of thawing, the problem of distribution is that partial boiling occurs when the electric field is concentrated, so the distribution must be improved even at the cost of some efficiency.

When warming a dish that has been cooled further (reheating), after putting the food 5 in the heating chamber 3, the start key 1
Press 9. Then, the control unit 11 determines that the food 5 is reheated by the signal from the operation panel 12, and the weight detector 1
3 and a signal from the state detector 14 determine various states such as the amount, shape and temperature of the food 5. Above all, it is important to judge whether the food 5 is in a liquid state, a solid state, or an intermediate state between liquid and solid. As one of the methods, there is a method in which the turntable 4 is rotated for a short period of time in the initial stage and then stopped to give vibration to the food 5, and the change with time of the vibration generated at that time is detected and judged. That is, if the object is a liquid, the vibration continues for a long time, and if the object is a solid, the vibration disappears in a short time. After that, the proper operation of the stirrer blade 8 is determined, the stepping motor 9 is driven to rotate, and the electromagnetic wave emission from the magnetron 1 is started before and after that. And when the food 5 is in a liquid state, the alignment state is stabilized with the turntable 4 stopped as in the case of the milk described above,
Heat efficiently. On the other hand, when the food 5 is solid, the turntable 4 is rotated to make the concentric heating distribution uniform. Furthermore, when the food 5 is in a state between liquid and solid,
The turntable 4 is repeatedly rotated and stopped.
After that, the weight detector 13 or the state detector 14 heats for a predetermined time, or the heating is terminated when the temperature reaches an appropriate temperature. In the case of the liquid food 5, even if the turntable 4 is stopped like the above-mentioned milk, if the electric field is concentrated on the bottom surface, convection will naturally produce a good distribution and stable and proper alignment will be obtained. It can be heated in the state and the efficiency is improved.

6 to 9 are configuration diagrams showing the results of simulating the electric field inside the high-frequency heating device.

FIG. 6 is a perspective view of a high frequency heating apparatus according to an embodiment of the present invention. Electromagnetic waves are excited from the feeding point 21 which is the antenna of the magnetron 1.

FIGS. 7 and 8 are perspective views cut along the line BB 'to simulate the electric field distribution of the high-frequency heating apparatus shown in FIG. 6 (in the case where there is no food). It is indicated by a line. (It can be considered that the electric field is stronger (belly) at a place where the annual ring-shaped pattern is more complicated.) This indicates a difference in electric field distribution depending on the position of the opening.

FIG. 7 shows the case where only the first opening 6A is opened, and the antinode of the electric field is 4 in the X direction in the heating chamber 3.
First, there are three electric field antinodes in the Y direction and one electric field antinode in the Z direction.

FIG. 8 shows a case where only the second opening 6B is opened, and the antinode of the electric field is 5 in the X direction in the heating chamber 3.
First, there is one antinode of the electric field in the Y direction and one antinode of the electric field in the Z direction.

Here, the reason why the electric field distribution as shown in FIGS. 7 and 8 occurs will be added. First, the propagation of electromagnetic waves in the waveguide 2 will be described.

FIG. 9 is a sectional view showing the main part of the high-frequency heating apparatus according to the embodiment, and shows only the magnetron 1, the waveguide 2, the heating chamber 3 and the first opening 6 in a simple manner. The distance L between the feeding point 21 of the magnetron 1 and the center 22 of the opening 6 is an odd number of λg / 4, where λg is the wavelength of the electromagnetic wave transmitted to the left in the waveguide 2 (wavelength in the tube). Double the distance. This is because when the electromagnetic wave is transmitted through the waveguide 2, it travels in the left direction in FIG. 9 while repeating the strength and weakness based on the guide wavelength λg determined by the shape of the waveguide 2, and λg /
The electric field is always weakened at a position of an odd multiple of 4 (in the transmission in the waveguide, the magnetic field and the electric field are in phase with each other and the magnetic field is also weakened), so that the electric field is weakened at the position of the center 22. Here, L = λg × 9/4. Also, the solid arrow indicates the direction of the strong electric field, and the direction of the electric field (and magnetic field) is opposite every λg / 2, so λ from the feeding point 21
The direction of the arrow is reversed every time the distance is separated by g / 2, and each of them repeats the inversion at the reciprocal period of the frequency of 2.45 GHz. In FIG. 9, since it is connected to the opening 6 of the heating chamber 3 at a weak electric field (and magnetic field),
Electromagnetic waves efficiently enter the heating chamber 3 without disturbing the electric field in the waveguide 2.

Here, the guide wavelength λg propagating in the waveguide 2
9, the depth of the waveguide 2 is C, the thickness is D, the number of intensity peaks of radio waves in the depth direction is m,
When n is the number of peaks and dips of the electromagnetic wave in the thickness direction and λ is the wavelength of the electromagnetic wave, the following equation 2 is obtained. Here, in vacuum, λ≈12
It is 2 mm. Generally, m = 1 and n = 0 are often adopted,
At this time, it becomes (Equation 3). C = 80 as a concrete value
If mm and D = 40 mm, then λg≈188 mm (however, all dimensions are internal dimensions not including the plate thickness).

[0054]

[Equation 2]

[0055]

(Equation 3)

Next, resonance of electromagnetic waves in the heating chamber 3 at this time will be described. In the case of FIG. 9, the electromagnetic waves in the heating chamber 3 tend to resonate, but opposite strong electric fields 23, 24 (solid arrows) that sandwich the opening 6 are generated, and the opening in the heating chamber 3 is generated. At 6, the electric field becomes stable in a resonance state in which the electric field becomes weak (a node). At this time, the electromagnetic waves enter the heating chamber 3 most efficiently (however, in the resonance state, the phase of the electric field and the magnetic field shifts by 90 °, unlike the transmission state like in the waveguide 2).

The resonance state is determined by the shape of the heating chamber and the position of the opening. In the case of FIG. 7 showing the electric field distribution in the heating chamber 3 at this time, four in the X direction of the heating chamber and three in the Y direction, Z
One strong electric field is generated in the direction. This is the antinode of the electric field caused by the electromagnetic waves being distributed as standing waves in the heating chamber due to the resonance state, and the number of antinodes is called a mode. Usually, when the shape of the heating chamber 3 is three-dimensionally expressed and the dimensions in each direction are x, y, and z, if the antinodes of the electric field are m, n, and p in each direction, the mode is (mnp). There is. In this embodiment, the depth x of the bottom of the heating chamber 3
And the center position of the first opening 6 is made to coincide with the center position of the width y, and at the same time, a strong electric field is generated so as to sandwich the opening 6 (so that the opening 6 serves as a node). Therefore, even mode (m; even) in the depth x direction.
Is likely to occur, and an odd mode (n; odd number) is likely to occur in the width y direction, and at the same time, other modes are difficult to occur. 8 is the same as FIG. 7 is the mode (431).
It is easy to see that is the mode (511).

In conclusion, the electric field distribution (that is, the heating distribution) can be changed depending on the position of the opening 6.

For reference, when the food 5 is not in the heating chamber 3 and the heating chamber 3 is a rectangular parallelepiped, the heating chamber 3 can be considered as a cavity resonator, and the size and opening of the heating chamber 3 can be considered. From the position of 6, it is possible to determine the mode in which the player can stand. The dimensions of the heating chamber 3 are x, y, and z, and the number of modes standing in each direction is a combination of m, n, and p satisfying (Equation 4) (x, y, z
z is a unit of mm, and m, n, and p are integers).

[0060]

[Equation 4]

On the other hand, when the food 5 is present, the deviation from (Equation 4) occurs due to the influence of wavelength compression due to the dielectric constant of the food. However, it was found experimentally that even if the food 5 is present, the mode satisfying (Equation 4) is about to stand near the opening 6, and the mode is often disturbed at a position away from the opening 6. Is coming. Therefore λ ≈ 122 mm
As an example for setting the mode (431) in (4), x = 330 mm, y = 300 m, which is a dimension that substantially satisfies (Equation 4).
It is possible to select m, z = 215 mm or the like.

FIG. 10 is a characteristic diagram showing the heating efficiency of one embodiment of the present invention. FIG. 10 is a Smith chart showing the matched state of the load viewed from the magnetron 1, and the hatched portion is a high efficiency region 25 (a region where electromagnetic waves enter the heating chamber 3 most efficiently). For certain food 5, if the stirrer blade 8 is rotated while the turntable 4 is stopped,
Characteristic changes of E to F to G to H to I to J to K to E are shown. That is, it indicates that the matching state can be changed depending on the position of the stirrer blade 8. Further, when the turntable 4 is rotated in a state where the stirrer blade 8 is stopped at the position of the characteristic of J, characteristic changes of J to L to M to N to O to J to ... That is, it indicates that the alignment state changes depending on the rotation of the turntable 4.

In conclusion, the alignment state can be changed depending on the positions of the stirrer blade 8 and the turntable 4.

At this time, in order to maximize the efficiency, it is preferable to stop the stirrer blade 8 at the position of the characteristic J while keeping the turntable 4 stopped. Of course, both may have to be rotated for distribution, as in the case of thawing frozen foods described above, but the liquid food 5
In the case of, both can be stopped to maximize efficiency. However, since the characteristics of FIG. 10 change depending on conditions such as the material / shape of the food 5, the position where the food 5 is placed, the temperature, etc., the condition detector 14 may detect the matching state, or the material / shape / location of the food 5 may be detected beforehand. There is a method of preliminarily storing the optimum positions of the turntable 4 and the stirrer blades 8 as a data base in the microcomputer in the control unit 11 for each condition such as the position and the temperature. With this method, the control unit 11 can perform control for optimum heating based on the information from the operation panel 12, the weight detector 13, the state detector 14, and the like and the database.

[0065]

As described above, the high frequency heating apparatus of the present invention has the following effects.

(1) Since the rotating body and the plurality of openings are provided in the waveguide, the rotation of the rotating body switches between the openings that easily emit electromagnetic waves and the openings that do not easily emit electromagnetic waves.
Apparently, electric fields generated from various feeding points can be switched frequently, and the object to be heated can be uniformly heated as a whole.

Further, since the rotating body is formed inside the waveguide, it is possible to maintain the effective volume of the inside of the heating chamber with respect to the entire size without taking up space with a simple structure.

Similarly, the consumption of extra power can be suppressed as much as possible. (2) Since the rotating plate is configured to switch a plurality of operation patterns in response to the input of the operation key, it is possible to heat while switching the optimal electric field distribution according to the object to be heated and the entire heating sequence as compared with the case of constant rotation. It can be heated more uniformly.

On the other hand, when the distribution is not required to be good enough to switch the electric field distribution (for example, milk-like liquid such as milk whose distribution is uniform if only the bottom surface is heated by convection), the best matching can be obtained. It is also possible to stop the rotating body in the open position. At this time, since the object to be heated can be efficiently heated, the heating time is short and the waiting time for the user can be shortened. Similarly, loss can be reduced and power can be saved.
Further, similarly, heat stress in the electromagnetic wave radiation part is reduced, and reliability is increased.

(3) Since the detector detects the condition of the object to be heated or the inside of the heating chamber and the rotating body switches a plurality of operation patterns accordingly, an optimum electric field distribution can be obtained according to the condition of the object to be heated. Since heating can be performed while switching, heating can be performed more uniformly.

On the contrary, the detection unit determines that the distribution is not required to be good enough to switch the electric field distribution (for example, a liquid such as milk which makes the distribution uniform if the bottom surface is heated by convection). Then, the rotating body can be stopped at the most aligned position thereafter. At this time, since the object to be heated can be efficiently heated, the heating time is short and the waiting time for the user can be shortened. Similarly, loss can be reduced and power can be saved. Further, similarly, heat stress in the electromagnetic wave radiation part is reduced, and reliability is increased.

(4) When the frozen food is used (in the case of thawing and cooking), the rotating body is rotated, so that the electric field in the heating chamber is constantly changed and the concentration of electromagnetic waves on a part of the frozen food can be prevented. Therefore, it is possible to prevent the uneven distribution of distribution peculiar to thawing that only the part is boiled while the whole is frozen.

(5) When the milk or soup is input with the operation keys, the food placing table is not rotated, so that the alignment state does not change due to the rotation. At this time, if matching is achieved, heating can be performed most efficiently. Further, at this time, electric power for rotating the food placing table is not required, so that power saving can be achieved. In general, liquid products such as milk and soup have little effect on the distribution due to the rotation or stop of the food placing table, so that the problem of uneven distribution does not occur.

(6) When the detection unit determines that the object to be heated is liquid, the food placing table is not rotated, so that the alignment state does not change due to the rotation. At this time, if matching is achieved, heating can be performed most efficiently. Further, at this time, electric power for rotating the food placing table is not required, so that power saving can be achieved.

[Brief description of drawings]

FIG. 1 is a top sectional view of a high frequency heating apparatus according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the high-frequency heating device.

FIG. 3 is a side sectional view of a high frequency heating apparatus according to another embodiment of the present invention.

FIG. 4 is a side sectional view of a high frequency heating apparatus according to another embodiment of the present invention.

FIG. 5 is a front view of the main part of the operation panel of the high-frequency heating device according to the embodiment of the present invention.

FIG. 6 is a perspective view of the high-frequency heating device of the present invention.

FIG. 7 is a perspective sectional view showing isoelectric field strength lines of the high-frequency heating device.

FIG. 8 is a perspective sectional view showing isoelectric field strength lines of the high-frequency heating device.

FIG. 9 is a cross-sectional view of the main parts of the high-frequency heating device.

FIG. 10 is a characteristic diagram of a high-frequency heating device according to an embodiment of the present invention.

FIG. 11 is a sectional view of a conventional high-frequency heating device.

FIG. 12 is a sectional view of a main part of another conventional high-frequency heating device.

FIG. 13 is a sectional view of another conventional high-frequency heating device.

FIG. 14 is a sectional view of another conventional high-frequency heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetron (electromagnetic wave radiation part) 2 waveguide 3 heating chamber 4 turntable (food placing table) 5 food (object to be heated) 6 opening 8 stirrer blade (rotating body) 11 controller 12 operation panel 13 weight detector 14 State detector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H05B 6/68 V 7361-3K

Claims (9)

[Claims] 1. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiation part for radiating electromagnetic waves, and a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiation part into the heating chamber through a plurality of openings. A high-frequency heating device having a configuration including a rotating body that operates in the waveguide and is made of a conductive member, and a control unit that controls emission of electromagnetic waves from the electromagnetic wave emission unit and operation of the rotating body. 2. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating part for radiating electromagnetic waves, a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiating part into the heating chamber through an opening, and A rotating body in the waveguide, which has one or more operation patterns and is made of a conductive member, and operation keys for inputting the type of the object to be heated, the size of the heating output by electromagnetic waves, the setting of the heating time, and the like. A high-frequency heating apparatus having a configuration including: a control unit that controls the emission of electromagnetic waves from the electromagnetic wave emission unit and the operation of the rotating body according to the input of the operation key. 3. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber through an opening, and A rotating body that is in the waveguide and has a plurality of operation patterns and is made of a conductive member, a detection unit that detects at least one of the physical quantity of the object to be heated or the state in the heating chamber and its change, and the detection unit. A high-frequency heating device having a control unit that controls the emission of electromagnetic waves from the electromagnetic wave emission unit and the operation of the rotating body according to the output of the. 4. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber through an opening, and The object to be heated has a rotating body which is in the waveguide and has a plurality of operation patterns and which is made of a conductive member, and a control section which controls the emission of electromagnetic waves from the electromagnetic wave emitting section and the operation of the rotating body. A high-frequency heating device configured to rotate the rotating body when a frozen food is used as. 5. A heating chamber for loading and unloading an object to be heated, a food placing table on which the object to be heated is placed and rotating, an electromagnetic wave radiating section for radiating an electromagnetic wave, and an electromagnetic wave radiated from the electromagnetic wave radiating section. Through the opening into the heating chamber, an operation key for inputting the type of the object to be heated, the size of the heating output by electromagnetic waves, the setting of the heating time, etc., depending on the input of the operation key It has a control unit for controlling the radiation of electromagnetic waves from the electromagnetic wave radiation unit and the rotation operation of the food placing table, and controls so that the food placing table is not rotated when milk or soup is input with the operation keys. High frequency heating device of the configuration. 6. A heating chamber for loading and unloading an object to be heated, a food placing table on which the object to be heated is placed and rotating, an electromagnetic wave radiating section for radiating an electromagnetic wave, and an electromagnetic wave radiated from the electromagnetic wave radiating section. A waveguide that guides into the heating chamber through an opening, and a detection unit that detects at least one of the physical quantity of the object to be heated or the state inside the heating chamber and its change,
When the detection target determines that the object to be heated is liquid, the control unit controls the radiation of electromagnetic waves from the electromagnetic radiation unit and the rotation operation of the food placing table according to the output of the detection unit. Is a high-frequency heating device configured to control the food placing table so as not to rotate. 7. The high-frequency heating device according to claim 1, wherein the rotating body is formed in a plate shape. 8. The high-frequency heating device according to claim 1, wherein the rotating body has a rod shape. 9. The high-frequency heating device according to claim 1, wherein the rotating body has a blade shape.