JPS5830713B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heating device that heats an object using radio wave energy, and more specifically, the present invention relates to a high-frequency heating device that uses radio wave energy to heat an object.

It is well known that radio waves in the microwave band are used to heat objects.

A common configuration of such high-frequency heating devices is one in which radiated radio waves from a radio wave generation source such as a magnetron are supplied directly or indirectly through a waveguide into a cavity called an open cavity in which an object to be heated is housed. be.

However, the cavity requires an opening/closing door to take the heated object in and out of the cavity, and if the means to prevent the emitted radio waves from this door is incomplete, the heated object may be heated during operation. The radio wave energy for this purpose is transmitted to the outside,
There is a risk of causing various types of radio wave interference.

Therefore, this type of device requires reliable means for preventing radio waves.

The object of the present invention is to provide means for solving the above-mentioned problems.

That is, a metal cylindrical body having a transmission width of λ/2 or less with respect to the used wavelength λ is interposed in the attenuation groove of the deafening radio waves to effectively attenuate the deafening radio waves, and at the same time, other interference prevention means are also used. The aim is to use this interaction to reliably prevent deafening radio waves.

Examples will be described below with reference to the accompanying drawings. In FIG. 1, a door 3 is attached to the main body 1 so as to be openable and closable.

A sectional view of the door 3 along line A-Person' is shown in FIG.

The cavity 2 that accommodates the object to be heated has an opening 21 through which the object to be heated can be taken in and taken out, and a planar peripheral portion 22 is formed.

The opening 21 is closed with a door 3.

The door 3 includes a door body 31, a metal plate 6 equipped with a group of small holes that allow the inside of the cavity to be seen through and suppress radio waves, and a dielectric cover for protecting the metal plate 6 provided with the group of small holes. The metal plate 6 is sandwiched between the transparent bodies 9 and 10.

The dielectric transparent bodies 9 and 10 prevent wires, etc. from being inserted into the cavity 2 from the small hole group, and prevent food scraps from entering the small hole group. This is a well-known means installed with the aim of doing so.

Metal body 6 and dielectric transparent body 9 equipped with these small hole groups
and 10 are fixed together with the retaining plate 7 to a mounting flange portion welded to the door body 31 with mounting screws 8.

As shown in FIG. 2, the door body 31 is provided with a radio wave attenuation groove 32, and the radio wave attenuation groove 32 has a wavelength of λ/
A metal cylindrical body 4 is interposed having a transmission width of 2 or less, that is, L is λ/2 or less in FIGS. 3a and 3b.

The radio wave attenuation groove 32 forms an opening facing the peripheral edge 22 of the cavity 2, and the opening is covered with a dielectric attenuation groove cover 5.

The attenuation groove cover 5 is a well-known means for preventing dirt such as food from entering the radio wave attenuation groove 32 to prevent the door body 31 from becoming unsanitary. .

The damping groove cover 5 is held by the pressing force of the holding plate.

Further, the metal cylindrical body 4 is pressed and clamped to the door body 31 by the damping groove cover 5.

On the other hand, at the entrance of the radio wave attenuation groove 32 on the opening 21 side of the cavity 2, there is a narrow radio wave passage 2 along the inner wall 23 of the cavity 2.
4 is formed.

In the embodiment, the narrow radio wave passage 24 is formed by a small gap between the bent piece γ1 at the peripheral edge of the holding plate 7 and the inner wall 23.

Furthermore, a narrow radio wave passage 12 is also formed between the metal protruding piece 11 surrounding the door 3 and the door body 31.

In the embodiment, the narrow radio wave passage is formed by a cabinet made of iron plate with a curled end placed so as to surround the door 3, and a small gap between the cabinet and the door body 31. .

Here, the protruding piece 11 does not necessarily have to have the configuration as in the embodiment, and may be made of a material such as an iron plate or stainless steel by welding to the cavity 2, a material such as aluminum or the like with screws, or a material such as a plastic material. Other configurations are also possible, such as arranging these metallic materials on the sash by adhering them or the like.

This embodiment is configured as described above.

Next, the functions of each part will be explained.

Radio waves traveling from the opening 21 of the cavity 2 toward the peripheral edge 22 form paths P and Q in FIG.

The radio wave in the Q direction is attenuated by the attenuation groove 32 and passes through the transmission path 41 of the metallic cylindrical body 4 .

As mentioned above, the transmission line 41 has a wavelength of λ/2 for the used wavelength λ.
Since it has the following transmission width, it causes a phase delay with respect to radio waves transmitted in free space.

For this purpose, by selecting appropriate dimensions for Hole, W, and H in Figure 3a, it is possible to create a radio wave that takes a path of Q compared to a radio wave that takes a path of P (solid line) as shown in Figure 4. The phase difference (dotted line) becomes 180° at the confluence point of the radio waves of the other party, that is, eight points in FIG. 2, and the radio waves of the other party cancel each other out.

In order to eliminate the interference radio waves, it is necessary to set the amplitude and phase relationship of the radio waves passing through the paths of P and Q to cancel each other out. A transmission path 41 having the following transmission width is continuously provided, W,
This is possible by appropriately selecting dimensions such as H and L.

Furthermore, as shown in FIG.
By combining the radio waves in the path of the radio waves, it is possible to reduce the radio waves transmitted to the outside, and furthermore, it is possible to reduce the cost.

On the other hand, the narrow radio wave paths 12 and 24 perform impedance matching for the radio waves on the P and Q paths.

In other words, it performs an adjustment action to make the relationship between the phases and amplitudes of the radio waves on the paths of P and Q so that they cancel each other out.

Furthermore, the purpose of providing a plurality of narrow radio wave paths 12 and 24 is to reduce the amplitude of the radio waves in the P and Q paths in particular.

In the example, in Figure 3, W = 7.5 (m), H = 26 (m), L = 15 (m).
, using a metal cylindrical body with G = 15 (mm), the height of the door in Figure 1 is 290 (mm), the width is 390 (T), the depth is 28 (mπ), and the radio wave attenuation groove in Figure 2 is The average length of B is 60 (++ m), and B = 5 (
1nTK) and C20 (1nr!L) and D=15C
A wireless radio wave prevention means is constructed with a narrow radio wave passage of E = 4 (mi) between
I measured the power density of deaf radio waves at a CTt distance away.

As a result, it has become possible to significantly reduce the noise radio waves to 0.01 mw/c4 or less.

In the embodiment, the radio wave attenuation groove is formed in the door 3, but the radio wave attenuation groove 32 is formed on the side of the cavity 2 or on the side of the door 3 and the cavity 2, and Even if 4 is interposed in the radio wave attenuation groove, the same effect can be obtained.

As described above, according to the present invention, it is possible to provide a highly reliable means for preventing deafening radio waves.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a high-frequency heating device according to the present invention,
FIG. 2 is a sectional view taken along the line AA'. FIG. 3 is a perspective view of the metal cylindrical body according to the present invention, and FIG. 4 is an explanatory diagram for explaining the effect of reducing deafening radio waves. 2...Cavity, 21...Opening, 24.
...Narrow radio channel, 3...Door, 31.
... Door body, 32 ... Radio wave attenuation groove, 4
...Metal cylindrical body, 41...Transmission line, 11...Protruding piece, 12...Narrow radio wave passage.

Claims (1)

[Claims] 1. A door 3 is provided for sealing an opening 21 of a cavity 2 that stores an object to be heated, and a radio wave attenuation groove 32 is formed on the cavity 2 or the door 3 or its partner, and the radio wave attenuation groove 32 is used. A metal cylindrical body 4 having a transmission path 41 having a transmission width of λ/2 or less with respect to the wavelength λ is interposed, and the entrance of the radio wave attenuation groove 32 on the opening 21 side of the cavity 2 is cavity 2
A high-frequency heating device characterized by having a narrow radio wave passage 24 along an inner wall 23 of the door 3, and a narrow radio wave passage 12 between a metal projecting piece 11 surrounding a door 3 and the door body 31.