JPS5832480B2 - Koushiyuuhakanetuki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heater equipped with a surface wave line, and its main purpose is to separate a space for exciting surface waves and a space for heating an object by the excited surface waves. It is to be.

Another object of the invention is to achieve surface wave heating with a simple construction.

Yet another object of the present invention is to combine surface wave heating with conventional microwave heating.

Still another object of the present invention is to provide a high frequency heater with high heating efficiency that can sufficiently heat even thick objects.

Still another object of the present invention is to provide a high frequency heater that can be safely handled by general consumers.

Microwave waveforms called surface waves are generally applied in various fields of high frequency engineering, and are used in traveling wave tubes, transmission circuits, and the like.

Generally, microwave surface waves have the following characteristics.

1 Surface waves exhibit an exponentially reactive decrease in the direction perpendicular to the transmission direction away from the surface of the transmission system, and there is no power propagation or radiation in this direction.

Further, dielectric flat plates, pleated conductor flat plates, and the like are known as circuits for transmitting such surface waves.

Various ideas for applying this surface wave to microwave heating have been disclosed in the past.

However, this type of conventional technology has the following drawbacks.

FIG. 1 is a theoretical sectional view of a high-frequency heater using a toothed circuit, where C is a metal toothed circuit, B is a high frequency source, and a coupling portion G excites surface waves in the toothed circuit.

At this time, the tooth profiles are joined together by the vicinity A of the tip of the tooth.

In this type of heating line, the object to be heated is placed in the space A where the mutual tooth profiles are radio-coupled, so changes in the condition of the object to be heated may cause the mutual connection state of the tooth profiles to change. The drawback is that it varies greatly.

Therefore, when such a surface wave line is used for home use, there is a drawback that the line does not operate satisfactorily because the shape and type of the object to be heated are indeterminate.

As explained above, 1. Manufacturing is difficult because the surface wave line has a tooth shape.

2. Since the space in which the surface waves are excited and the space in which the heated object is placed are the same, it is difficult to accommodate changes in the shape, type, etc. of the heated object.

3 Can only be used for continuous heating of thin materials.

In other words, in embodiments that rely only on surface wave heating, as shown in feature 1 of surface waves, the energy distribution decreases exponentially as the distance from the surface wave line surface increases, so if the object to be heated is thick, The energy of the radio waves does not sufficiently penetrate into the heated object.

Therefore, it has the disadvantage that only the surface wave line side of the object to be heated is heated, so it has the disadvantage that only thin objects such as cloth or films can be heated.

In addition, there is another conventional example of a high-frequency heater using a waveguide-type surface wave line, and this system uses a waveguide WG with a periodicity of It is a kind of ladder-shaped surface wave line, which is equipped with a slit S.

In this case, the film-shaped object to be heated is continuously sent so as to cover the slit S, and the radio wave power for exciting the surface waves is supplied from the internal space F of the waveguide WG.
can be improved.

However, there are insufficient measures to protect the human body from radio wave energy emitted into the external space, and there is a risk that the human body may accidentally approach the surface wave line.

Furthermore, similar to the above-mentioned drawback 3, this method has the drawback that it is insufficient to deal with a large number of objects to be heated, such as thick foods.

The present invention provides a surface wave heating and high frequency heater that improves various drawbacks of the conventional examples as explained above.
Examples of the present invention will be described below.

In FIGS. 2 and 3, 1 is a door, 2 is a main body, 3 is a magnetron that oscillates microwaves, 4 is a heating chamber, 5 is an object to be heated, and 9 is an antenna of the magnetron 3.

Note that the numbers referenced in the drawings refer to the same ones in other drawings as well.

Reference numeral 7 denotes a metal plate, and slit-like holes 8 are provided substantially periodically on the plate surface to form surface wave lines 14.

Reference numeral 6 denotes a space of a radio wave passage formed by the heating chamber bottom plate 10 and the metal plate 7.

The surface wave line used in this embodiment is a type of ladder circuit, and the ladder circuit has slits S formed at approximately equal intervals in one side wall E of the waveguide WG, as shown in FIG.

It is well known that surface waves are generally excited on a metal plate in which radio impedance elements such as slits are periodically arranged.

The correspondence between Fig. 4, Fig. 2, and Fig. 3 is that the cavity F of WG is space 6.
, E corresponds to the metal plate 7, and slit 8 corresponds to S.

According to the configuration of the present invention, radio waves emitted from the magnetron antenna 9 pass through the radio wave path 6 and excite surface waves in the periodically provided slit group 8.

The excited surface waves then heat the object placed on the metal plate 7.

At this time, as described in feature 1 of surface waves, the microwave energy is distributed exponentially as it moves away from the surface wave line 14 above.

Therefore, microwave energy is concentrated on the heated object placed on the surface wave line.

Therefore, unlike a conventional microwave oven that radiates radio waves throughout the heating chamber space, heating efficiency generally increases because the energy density near the object to be heated increases.

In addition, this degree of concentration can be changed by appropriately selecting the size and pitch of the slits 8, so it is sufficient to design the slits 8 to suit the heated objects that are handled most often. It is possible to prepare a surface wave line formed with a surface wave line and replace it as an attachment depending on the type of object to be heated.

Further, in practice, it is preferable to cover the slit 8 by covering the metal plate 7 with a dielectric material such as plastic, as shown in FIG.

As explained above, since the radio wave energy for exciting the surface waves is supplied through the radio wave path 6 provided at the lower part of the surface wave line 14, the disadvantage 2 of the conventional example can be improved.

Another effect of providing the radio wave passage 6 is that by appropriately selecting the width, height, and length of the radio wave passage 6 so that one or more radio wave modes exist within the radio wave passage 6, each mode can be adjusted. Since the states of the correspondingly excited surface waves are different, the energy density on the surface wave line 14 can exhibit various states.

In other words, the radio waves that best excite the surface waves are the radio waves that travel in the periodic direction of the surface wave line, but the radio waves that travel in a direction different from this direction do not sufficiently excite the surface waves and may be transmitted through the slit 8 or inside the heating chamber. radiates through other gaps.

Therefore, in this case, the object to be heated is heated as a combination of heating by surface waves and heating by other radio wave modes.

Therefore, even if the object to be heated is thick, it is sufficiently heated, so that the disadvantage 3 mentioned above in the conventional example can also be improved.

Also in this case, a part of the oscillated energy is concentrated in the vicinity of the object to be heated as a surface wave, so that the heating efficiency is improved.

Furthermore, since it is configured with a heating chamber, there is no danger of the human body accidentally approaching the space where radio waves are being radiated, so it has the great effect of being able to be used safely in ordinary homes.

Furthermore, although the position of the magnetron is closer to the edge in the embodiment, there is of course no essential difference even in the center.

At the same time, it is only a design problem that could easily be considered, such as a method of feeding power using a waveguide.

The surface wave line that can be used in the present invention can be a plate made of a dielectric layer, or a plate in which metal conductive members are arranged substantially periodically.

These can be easily manufactured by punching a flat sheet metal, etching a printed circuit board made of resin and metal, or plating resin.

In some cases, the conductor rods and conductor rings may be arranged approximately periodically and three-dimensionally.

In short, this is possible as long as it is a surface wave line that allows radio waves to travel on both sides.

Furthermore, the radio wave passage 6 does not need to be formed of a space and may be filled with a dielectric material, and depending on the design of the surface wave line, the heating chamber does not need to be formed only of a conductive material, and a portion of it may be made of a dielectric material such as plastic. It is also possible to form it in the body.

However, in this case as well, at least a portion of the portion forming the radio wave path must be made of metal.

In order to further increase safety, it is necessary to use a well-known radio wave shielding device around the door, or to use a safety switch that is linked to the opening and closing of the door.

Furthermore, if the surface wave line is made of metal and the heating chamber wall is also made of metal, spark discharge may occur at the part where the line and the wall come close to each other or come in contact with each other, which may be inconvenient. In order to prevent this, the above-mentioned disadvantages can be solved by coating the end of the surface wave line with resin, etc., inserting a dielectric between the line and the wall, or welding or screwing the line and wall together. Although the need may arise, this is a problem that can be easily resolved by those skilled in the art.

As explained above, according to the present invention, the following effects can be expected.

1 The radio wave path for exciting surface waves and the heating space where the heated object heated by the surface waves is placed are separated, so energy that becomes surface waves is stably supplied even when the heated object changes. can.

2. Combination of surface waves and conventional microwaves can be easily implemented depending on the size of the radio wave path or other configurations.

Furthermore, since it has a heating chamber, ordinary microwave heating is also possible.

3. Since it uses surface wave heating, it has high heating efficiency and saves resources.

4. Since it is configured as a heating chamber box, there is no risk of the human body accidentally approaching the radio wave radiation space, making it extremely safe.

5. The surface wave line can be constructed using simple methods such as sheet metal processing, making it inexpensive.

6. Since various surface wave lines can be used, the surface wave line can be selected according to the type of object to be heated.

7. The heating state can be controlled simply by controlling the radio wave distribution within the radio wave path, and the heating state can be regulated simply by placing metal or dielectric material within the radio wave path.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the principle of high-frequency heating using a tooth-shaped circuit, Fig. 2 is a perspective view showing an embodiment of the present invention, with main parts cut away, and Fig. 3 is the same. 4 is an explanatory diagram of a ladder-shaped surface wave line, and FIG. 5 is a sectional view showing another embodiment of the surface wave line. 1...Door, 2...Body, 3...
...Magnetron, 4...Heating chamber, 5...
... Heated object, 6 ... Radio wave path, 14 ...
...Surface wave line.

Claims (1)

[Claims] 1. A heating chamber composed of a metal wall, a door that can be opened and closed at the opening of the heating chamber and substantially blocks radio waves from leaking to the outside, and a bottom plate of the heating chamber and an upper part of the bottom plate. a radio wave passage formed by a metal plate located thereon, and a magnetron that feeds radio waves into the radio wave passage; slit-shaped holes are provided in the metal plate almost periodically, and the metal plate passes through the radio wave passage periodically. A high-frequency heater configured to excite surface waves in the slit-shaped hole.