JPH06302381A - High-frequency heating device - Google Patents

Abstract

PURPOSE:To unify heat distribution on a heated ingredient such as a foodstuff and enable efficient heating to be made. CONSTITUTION:The connected section of a heating chamber 3 and a waveguide 2 is provided with the first opening 5 and the second opening 6 for introducing an electromagnetic wave from a magnetron 1 to the heating chamber 3. Also, a metal sheet 7 is constituted so as to shield and release the openings 5 and 6 on the basis of the control of a drive section 9 through a control section 8. According to this construction, a foodstuff 4 is heated via the selection of specific field distribution over each of the openings 5 and 6. Thus, uniform heat distribution and efficient heating can be realized.

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 by applying electromagnetic waves.

[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 FIG. That is, 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 17. , Heat food 4. Since the heating distribution of the food 4 is determined by the distribution of the electric field generated by the electromagnetic waves, the turntable 9 of the table on which the food is placed is rotated to make the heating distribution on the concentric circles uniform in order to suppress the unevenness of the heating distribution. . Further, as other means for homogenization, there are a stirrer for stirring electromagnetic waves by a metal plate in the heating chamber 3 and a rotary waveguide for rotating the metal part of the exit of the waveguide itself. Most types are available.

[0003]

However, in the above conventional structure, the turntable type does not move the feeding point of electromagnetic waves (where electromagnetic waves enter the heating chamber), so that the electric field distribution generated by the electromagnetic waves in the heating chamber is always constant. Even when the turntable is rotated, the distribution of the food in the radial direction and the distribution in the vertical direction as viewed from the center of rotation are not improved even when the turntable is rotated. There was a problem that non-uniformity remained.

In the case of a stirrer that stirs the electromagnetic wave or moves the feed point of the rotary waveguide to change the electric field distribution generated by the electromagnetic wave moment by moment, a standing wave is unlikely to occur in the heating chamber and the heating chamber 3 Since the matching state between the magnetron 1 and the magnetron 1 deteriorates and a part of the electromagnetic wave is returned to the magnetron 1 and converted into heat, there is a problem that efficiency is lowered. If the efficiency drops, the heating time becomes longer and the waiting time of the user becomes longer, the waste of power, the magnetron 1
Due to the increase of the heat stress, there are various problems such as decrease in reliability.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-frequency heating device capable of uniformly and efficiently heating at the end of heating and quickly heating.

[0006]

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

A heating chamber for loading and unloading an 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, the heating chamber and the waveguide. An opening provided at a connection portion with the metal plate, a metal plate capable of blocking or opening the opening, a drive unit for moving the metal plate, and a control for controlling the drive unit for operating the metal plate And a part.

Further, the plurality of openings are provided, and the metal plate operates so as to shield the other openings when one of the openings is opened.

Further, the wavelength of the electromagnetic wave in the waveguide is set to λg
In this case, the distance between the openings on the waveguide is an integral multiple of about λg / 2.

Further, it has a sensing means for detecting the state of the food, and the control section controls the driving section in response to a signal from the sensing means to operate the metal plate.

[0011]

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

The drive unit operates the metal plate based on a control signal from the control unit to block or open a part of the opening, thereby changing the feeding point in the heating chamber (that is, opening of the opening). Since the electric field distribution is unique to each feeding point, the heating distribution of the object to be heated is not constant but changes.

Further, the drive unit operates the metal based on the control signal from the control unit to open one of the plurality of openings and block the other opening, and change the opening to be opened. To With this, each time each opening is opened, each standing wave is generated by each opening and a corresponding electric field distribution can be provided, so that the food can be efficiently heated.

Further, since the distance between the openings is set to an integral multiple of λg / 2, a standing wave having a strong electric field can be formed even if any of the openings is opened.

Further, since the control unit controls the operation of the metal plate in response to the signal from the sensing means, the opening of the opening can be selected according to the quality of cooking.

[0016]

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

FIG. 1 is a block diagram of a high frequency heating apparatus according to an embodiment of the present invention. The electromagnetic wave emitted from the magnetron 1 serving as an electromagnetic wave radiating section passes through the waveguide 2 and the heating chamber 3
The food 4 inside is heated. At this time, the waveguide 2 and the heating chamber 3
There is a first opening portion 5 and a second opening portion 6 at the connection portion with and, which are selectively used depending on the operation of the metal plate 7. In the case of FIG. 1, the electromagnetic wave does not enter the heating chamber 3 by being shielded by the metal plate 7 from the first opening 5, and the electromagnetic wave is released from the metal plate 7 by the second opening 6 and the electromagnetic wave is released from the heating chamber. Enter within 3. The operation of the metal plate 7 is performed via the drive unit 9 by a signal from the control unit 8, and the metal plate 7 moves in the left-right direction in FIG. Regarding the timing of switching between the two openings 5 and 6, it may be possible to simply switch alternately at regular intervals, but in order to perform optimal heating for each state of the food 4, the food 4
It is conceivable to perform feedback control by sensing the state of. Here, the food 4 is placed on the turntable 9, the weight of the food 4 is determined by the weight sensor 10, and the weight is switched accordingly. Of course, the weight sensor
In addition to 10, it is possible to use various sensing methods such as shape recognition sensors, position sensors, and electromagnetic wave detection. The control unit 8 detects the weight of the food 4, controls the drive unit 9 to operate the metal plate 7 at an optimal timing according to the weight, controls the radiation of electromagnetic waves from the magnetron 1, and more. The operation of the food rotation drive unit 11 is controlled to rotate the turntable 9 in order to further uniformize the distribution.

Although not shown here, the two openings 5 and 6 are actually formed as in a conventional microwave oven.
It is conceivable to cover the resin with a resin cover with less high frequency loss. Further supplementing the specific configuration, the positional relationship among the magnetron 1, the first opening 5, and the second opening 6 is represented by the wavelength of the electromagnetic wave in the waveguide 2 (wavelength in the tube) λg. And λg / 2 are separated by an integer multiple. This is because when the electromagnetic wave emitted from the tip of the magnetron 1 propagates in the waveguide 2, it travels to the left in FIG. 1 while repeating the intensity at the in-tube wavelength λg determined by the shape of the waveguide 2, and thus λg / This is because the electric field is always strong at the position of an integral multiple of 2.

That is, in the structure of FIG. 1, the two openings are located at positions of strong electric fields and are connected to the heating chamber 3 by electric field coupling, so that electromagnetic waves can efficiently enter the heating chamber 3. Here, the definition of the guide wavelength λg will be described with reference to FIG. 1. The width of the waveguide 2 in the depth direction is a, the height in the vertical direction is b, the number of peaks of the electric field in the depth direction is m, When n is the number of peaks and dips of the electric field in the height direction and λ is the wavelength of the electromagnetic wave in a vacuum, the following equation is obtained. Generally, m = 1 and n = 0 are often adopted, and in this case, (Equation 2) is obtained. As specific values, if a = 80 mm and b = 40 mm, then λg = 188 mm.

[0020]

[Equation 1]

[0021]

[Equation 2]

Next, FIGS. 2 (a) and 2 (b) are main part configuration diagrams in one embodiment of the present invention, which are views seen from above (waveguide side) from AA 'in FIG. is there. Here, the metal plate 7 has a hole 12, and FIG. 2A shows a case where the first opening 5 is shielded by the metal plate 7 and the second opening 6 is opened. On the other hand, FIG. 2B shows a case where the second opening 6 is shielded by the metal plate 7 and the first opening 5 overlaps the hole 12 and is opened. Further, in FIG. 1, the two openings 5 and 6 can be shielded / opened by the single metal plate 7, but of course the metal plate may be provided independently for each opening.

3 (a) and 3 (b) are diagrams showing modes of the high frequency heating apparatus in one embodiment of the present invention. Figure 3
(A) is an example in which an electromagnetic wave is introduced from the first opening 5 into the heating chamber. If the electric field generated by the electromagnetic wave is strong within the broken line, there are three electric field peaks in the lateral direction and an electric field in the vertical direction. It is considered that there is one mountain. On the other hand, FIG. 3B is an example in which electromagnetic waves are introduced into the heating chamber from the second opening 6, and it is considered that there are two electric field peaks in the lateral direction and two electric field peaks in the vertical direction. Since the difference in the electric field distribution brings about the difference in the food heating distribution, it can be estimated that the distribution can be made uniform by properly using FIGS. 3A and 3B. Generally, when there is no food 4, the number of electric field peaks (modes) standing in each direction can be calculated depending on the shape of the heating chamber 3, and the feeding point (opening portion in the case of electric field coupling as in the present invention is the same) in the same heating chamber 3. It is possible to set multiple modes by selecting the position of (matches with). In addition, when food is included, some deviation may occur due to the influence of wavelength compression due to the dielectric constant of food, but this can be roughly estimated. Therefore, the distribution can be made uniform depending on how to select the feeding point by switching the shape of the heating chamber 3 and the plurality of openings. However, if the first opening portion and the second opening portion are opened at the same time, the average mode of both and the mode deviating to either one will be stable and will not be uniform. It is necessary to switch to the last. For reference, in the case of a rectangular parallelepiped heating chamber without food 4, the heating chamber dimensions are x, y, and z, and the number of modes standing in each direction is a combination of m, n, and p satisfying (Equation 3). (X, y,
z is in mm, m, n, and p are integers).

[0024]

[Equation 3]

FIG. 4 shows a weight sensor 10 according to an embodiment of the present invention.
It is a characteristic view which shows the timing of switching of the opening parts 5 and 6 by. The horizontal axis is the weight of the food 4, the vertical axis is time, and the total time during which the first opening 5 is open is 11 when the total heating time is lt. Therefore, the time during which the second opening 6 is opened is lt-l1. The ratio of the opening times of the openings 5 and 6 may be 1: 1 but, for example, as shown in FIG. 4, the weight range of the food 4 (less than m1, m1 or more and m1 or more).
(2), m2 or more) should be optimized by a method such as changing the characteristics. Further, as shown in FIG. 4, not only a method of switching the openings 5 and 6 in two stages of the first half and the second half but also a method of alternately switching several times is conceivable.

FIG. 5 is a block diagram of a high frequency heating apparatus according to another embodiment of the present invention. The waveguide 2 itself is divided in the middle, the first opening 5 is on the top surface of the heating chamber 3, and the second opening 6 is on the side surface of the heating chamber 3. Therefore, there are metal plates 13 and 14 and drive units 15 and 16, respectively, and the control unit 8 controls each of them.

Although only the case where there are two openings has been described here, of course, there is only one opening and there is a method of covering a part of it with a metal plate, or a structure having three or more openings. Conceivable.

[0028]

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

Since electromagnetic waves are introduced into the heating chamber by shielding or opening a part of the opening with a metal plate, it is possible to provide a plurality of electric field distributions generated by the electromagnetic waves at each feeding point, and to combine the respective electric field distributions. Can make the finished state of food more uniform. Therefore, the user can be satisfied with the quality of the work.

Similarly, it is easy to provide a standing wave to give an electric field distribution each time the openings are switched,
Since the food can be heated efficiently, the heating time can be shortened. Therefore, the waiting time is reduced for the user, and it is convenient and convenient.

Similarly, since the efficiency is high, the reflection of the electromagnetic wave to the electromagnetic wave radiating portion is reduced and the temperature rise can be suppressed, so that the safety and durability are improved.

Further, energy saving can be achieved for the same reason.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a high frequency heating apparatus according to an embodiment of the present invention.

FIG. 2A is a configuration diagram of main parts of the high-frequency heating apparatus. FIG. 2B is a configuration diagram of main parts of the high-frequency heating apparatus.

FIG. 3A is a diagram showing a mode of the high frequency heating apparatus, and FIG. 3B is a diagram showing a mode of the high frequency heating apparatus.

FIG. 4 is a characteristic diagram of an embodiment of the present invention.

FIG. 5 is a configuration diagram of a high-frequency heating device according to another embodiment of the present invention.

FIG. 6 is a block diagram of a conventional high-frequency heating device.

[Explanation of symbols]

 1 magnetron (electromagnetic wave radiation part) 2 waveguide 3 heating chamber 4 food (object to be heated) 5 first opening 6 second opening 7 metal plate 8 control part 9 drive part

Claims (4)

[Claims] 1. 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 the electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the guiding section. An opening provided at a connection portion with the wave tube, a metal plate capable of blocking or opening at least a part of the opening, a drive unit for moving the metal plate, and the metal plate for operating the metal plate. A high-frequency heating device configured to include a control unit that controls a drive unit. 2. A structure having a plurality of openings, wherein the metal plate operates so as to shield one of the openings when opening the other.
The high-frequency heating device described. 3. When the wavelength of the electromagnetic wave in the waveguide is λg, the distance between the openings on the waveguide is about λg /
The high-frequency heating apparatus according to claim 2, wherein the high-frequency heating apparatus has a configuration that is an integral multiple of 2. 4. A structure having a sensing means for detecting the state of the food, wherein the control part controls the drive part in response to a signal from the sensing means to operate the metal plate. 3. The high frequency heating device as described in 3.