JPS6331919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applied to a high-frequency heating device such as a microwave oven. Radio waves leak through the radio wave path.
The present invention relates to a device for sealing the leaked radio waves.

Currently, the chiyoke system as seen in US Pat. No. 3,182,164 is widely used as a radio wave sealing device. The radio wave system has a configuration in which a radio wave groove is provided in the radio wave path, and the distance from the heating chamber side end of the radio wave path (referred to as the gap start point) to the radio wave groove is used to calculate a quarter of the wavelength (hereinafter referred to as λ). 1, and the depth of the radio wave groove is set to λ/4. In the Chi-Yoke method, the distance from the gap starting point to the bottom of the radio groove is set to a dimension of λ/2, so the idea is that a radio wave impedance short-circuit condition at the bottom of the radio groove can be realized at the gap starting point. It is designed by In the Chi-Yoke system, there are improved prior art techniques that take measures against radio wave propagation in the longitudinal direction of the radio wave groove, and those that load a dielectric material within the radio wave groove to compact the geometric dimensions.

Since the above-described sealing principle is used in the above-mentioned sealing method, there is a problem in terms of compactness in that the dimension from the gap starting point to the radio wave groove cannot be made smaller than λ/4.

The first object of the present invention is to solve the problems of the conventional example.

The present invention is characterized in that a plurality of parallel line transmission lines are arranged in the radio wave passage in the direction around the door with substantially periodicity, and a T-branch is provided in the traveling direction of the parallel line transmission lines. Furthermore, it is characterized in that the cross-sectional shape of the T-branch portion is modified. By adopting such a configuration, both the gap from the gap starting point to the T-junction and the depth of the T-junction can be made smaller than λ/4.

The present invention has the following points: The conventional example is designed based on the idea that the radio wave sealing effect is simply reduced by reducing the impedance at the gap starting point, and there is no consideration given to the impedance seen from the radio wave groove to the outside through the radio wave path. We succeeded in making it more compact through analytical experiments by analyzing the following and adopting a new way of thinking about the radio wave sealing effect.

The key to the present invention is that the amount of radio wave leakage is proportional to the actual energy consumed by the impedance of the external space, and that it cannot be explained simply by the size of the impedance at the starting point of the gap.

The contents of the present invention will be explained below using FIGS. 1 to 5.

FIG. 1 is an explanatory diagram of the basic configuration of the present invention, and FIG. 2 is a perspective view of the main part of FIG. 1. Heating chamber 2 by main body 1
A door body having a sealing portion 4 provided on a part of a sealing plate 3 is provided for the opening of the heating chamber 2. The seal portion 4 consists of a T-branch portion 9 having a gap b ₁ depth l ₁ from the clearance starting point 5 to the transmission paths 6 and 7 and an opening 8 . The external space is indicated by 10.
11 is a parallel line transmission line. The transmission line and T branch are the second
As shown in the figure, a plurality of parallel line transmission lines each having a width a are arranged in the direction around the door via gaps. The sealing effect when this configuration is adopted is that the real part of the energy ratio is Real ( I learned that the experimental values can be explained by taking the idea that if P _L ), it is proportional to Real (P _L ) = RZov / RZov + R ² + X ² . The experimental results were as follows. In other words, when conducting an experiment with the shape shown in Figure 1, the dimension l ₁ needs to be several percent longer than λ/4, but the dimension from the clearance starting point 5 to the T-junction 6, and from the T-junction to the outside. The dimension up to the space can be smaller than λ/4. The present invention further proposes a configuration in which not only the dimension from the gap starting point to the groove but also the depth of the groove can both be made smaller than λ/4 by adopting the configuration shown in FIG.

Embodiments of the present invention will be explained using FIGS. 3 to 5. The feature of the configuration of the present invention is that the T-branch cross section has a larger gap than the T-branch entrance 9' and the T-branch bottom 9''(b'<b''). When , the absolute value of the impedance Zin per parallel line transmission line when looking from the T-branch opening 8 to the T-branch side is l ₃
This figure shows how the dimensions and overall depth _l4 change as parameters. This is b′=3mm, b″=6
It was obtained by setting mm and a=10 mm. Figure 5 shows the characteristic effects of the configurations shown in Figures 3 and 4: (i) The depth l ₄ of the T-branch can be shortened to 24 to 25 mm (l ₄ <λ/4≒30 mm) (ii) ) Impedance Zin in the case of Fig. 2 (b ₁ = 6 mm) where no deformation is applied to the T-branch
When l ₄ is set to 24 to 25 m, the maximum value of the absolute value |Zin| can be 4 to 10 times larger, which is advantageous in terms of sealing effect. It is shown that.

Due to the above invention, the problems of the conventional example (the depth of the groove was kept at λ/4, and furthermore, the length from the gap start point to the radio groove needed to be λ/4) can be solved.

The unique effects of the present invention are as follows.

(i) The depth of the T-branch groove can be made shallow.

(ii) Excellent radio wave sealing effect.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of the basic configuration of the present invention, and 3.
The figure is a sectional view showing one embodiment of the present invention, FIG. 4 is a perspective view of the same essential part, and FIG. 5 is a diagram illustrating the characteristics of FIGS. 3 and 4. 3... Sealing plate, 4... Seal portion, 9'... T-branch inlet portion, 9''... T-branch bottom.

Claims (1)

[Claims] 1. A heating chamber opening has a door body that can be opened and closed, and a plurality of parallel transmission lines having a T-branch provided on either the main body or the door body are arranged in the direction around the door via a gap, and The T-branch is a radio wave sealing device in which the bottom gap is wider than the entrance gap.