JPS6012758B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency heating device having a heating chamber, and in particular,
The purpose is to effectively suppress power leakage from the vicinity of the heating chamber entrance with a simple structure.

Conventionally, as a structure for suppressing this type of radio wave leakage, it is known to provide a so-called choke structure consisting of a resonant cavity with an input/4 length (^ is the effective wavelength of the leaked radio waves) around the entrance of the heating chamber.

However, although the choke structure exhibits a deterrent effect on leakage radio waves propagating in the input/fourth direction, it has almost no deterrent effect on radio waves having a propagation component in a direction perpendicular to the choke structure. In this way, leakage radio waves that cannot be suppressed by the choke structure can be avoided by placing a radio wave absorber such as ferrite on the outside of the choke structure, or by providing multiple slits in the conductor plate as seen in Japanese Patent Publication No. 51-22663. It is also known that this can be suppressed by disposing a periodic structure together with a choke structure. However, in order to completely suppress radio wave leakage in the above conventional technology, in addition to the choke structure, a radio wave absorber, a periodic structure, etc. are incorporated, so the radio wave leakage suppression mechanism tends to be complicated.

Furthermore, since the choke structure requires a considerable cavity volume, it also has the disadvantage that, for example, when it is provided in a door for opening and closing the heating chamber entrance, the door thickness becomes large. Therefore, the present invention provides a very simple and complete radio wave leakage prevention structure that essentially eliminates the need for choke structures, radio wave absorbers, periodic structures, etc.

In order to prevent radio wave leakage in a high-frequency heating device, the novel structure of the present invention includes a conductor resonator structure that has a resonance dimension relationship of leakage radio waves in two directions orthogonal to each other in the radio wave leakage path around the closing of the heating chamber. It is characterized by its placement.

In the above-mentioned conductor resonator, a dielectric is placed in the radio wave propagation path, and if the shape is made to have the resonance dimensions of the radio waves, the conductor itself acts as a resonator.

This principle itself is already known in the field of microwave communication technology, but unlike communication technology that handles weak microwave energy, it is used to prevent radio wave leakage in high-frequency heating equipment that handles strong microwave energy. Until now, it has not been recognized at all that dielectric resonators work effectively.
The novel idea of the present invention is that a dielectric resonator is applied to prevent radio wave leakage in a high-frequency heating device, and by specifying its form, complete prevention of radio wave leakage can be achieved using only the dielectric resonator. .

The present invention will be explained below with reference to Examples.

1 and 2 show a microwave oven as an example device, 1 is a heating chamber, 2 is a metal main body wall that spatially limits the heating chamber, and 3 is a rectangular closed front side of the heating chamber 1. It is a door that opens and closes.

The door 3 includes a door frame 5 having a central see-through window 4, a metal door inner plate 6 fixed to the inner surface of the door frame and having a large number of see-through holes in the portion corresponding to the see-through window 4, and the inside of the door frame 5. Transparent plates 7 and 8 are provided on the front and back surfaces of the door inner plate 6 to cover the pores of the plates. Although not shown in the figure, the door 3 has a hinge on its right end side, and its left end side rotates in the direction of the arrow as shown in the figure, about the hinge.

When the door is closed, the green outer periphery 6a of the door inner plate 6 comes into contact with the front surface 2a of the main body wall 2, and a radio wave leakage path is formed in the saddle portion, and the dielectric resonator mechanism, which is a feature of the present invention, is formed in the path. Although only a portion is shown in the figure, this arrangement is the same throughout the entire circumference of the rectangular opening of the heating chamber 1. A plurality of containers 10a, 10b, .

Specifically, each dielectric resonator 10a is composed of a square dielectric plate having a thickness t and a side 1, and is arranged at regular intervals d such that one side of the square is parallel to the heating chamber opening edge 11. ing. The important thing is that the length 1 of one side of the square conductor plate is related to the resonance dimension of the leaked radio wave. Now, if the wavelength of the leaked radio wave is ^ and the specific conductivity of the resonator 10a is r, then 1 is 1 = Voice; Defined by ÷. That is, the dielectric resonator 10a has two directions: a direction parallel to the peripheral edge 11 of the heating chamber closing (the direction in which each resonator is arranged) and a direction perpendicular thereto.
It constitutes a resonator for radio waves propagating in each direction, and therefore radio waves traveling in these two directions or radio waves having components traveling in each direction are greatly attenuated by the presence of the resonator and cannot reach the outside. In particular, radio waves propagating in a direction parallel to the surrounding green 11 of the heating chamber open □ are transmitted through the resonators 10a arranged in multiple stages in that direction.
exists, so it receives greater attenuation. For example, titanium oxide or alumina is suitable for the dielectric resonator 10a, and since these have low conductor loss, self-heating due to leakage radio waves is also low.

To give a specific numerical example, when using titanium oxide,
r is 36, so if the frequency of the radio wave is 2450 MHz, the above 1 will be about 5 ribs. Note that the above-mentioned d is set to a size that prevents radio waves from passing through this gap, and is, for example, on the 1-2 side. Further, the above t may be 1 to 2 skins. Due to the size of this t, a gap is created between the front surface 2a of the main body wall 2 and the outer peripheral edge 6a of the door inner plate 6, making the appearance unsightly. Hiding the gap. In the above embodiment, the back surface of the dielectric resonator 10a is metallized and fixed by soldering to the front surface 2a of the main body wall 2. However, as another method of fixing, each resonator may be similarly arranged and fixed on another metal strip. or, as shown in FIG. 3, each resonator 10a, 10a, . . .・
・．． ... may be buried and fixed to the front surface.

Moreover, each resonator 10a can also be arranged on the door inner plate 6 side. Further, in the above embodiment, each resonator 10a was square, but the shape of each resonator 10a is ^/4? The same effect can be achieved even if the resonance relationship is set to an odd multiple of , so the shape can also be rectangular accordingly.

Furthermore, it is preferable that the above resonance dimension relationship be satisfied with the door closed. Therefore, if the effective wavelength of radio waves changes between when the door is open and when the door is closed, the resonance dimension relationship is set to match when the door is closed. It is preferable to do so.

As is clear from the above explanation, according to the present invention, it is possible to completely suppress radio wave leakage using only a dielectric resonator composed of conductors having a specific dimension relationship, and the structure for suppressing the leakage is extremely simple. Since there is no need for a choke structure like this, the door thickness can be made thinner.

It goes without saying that the present invention can be used in combination with conventional deterrent structures.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, FIG. 2 is a perspective view of the main part, and FIG. 3 is a perspective view of a main part showing another embodiment. 1... Heating chamber, 10... Dielectric resonator mechanism. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. 2. The radio wave leakage path around the opening of the heating chamber is perpendicular to the radio wave leakage path.
A high-frequency heating device in which a dielectric resonator structure is arranged to have a resonance dimension relationship of leakage radio waves with respect to the direction. 2. The high frequency device according to claim 1, wherein the dielectric resonator structure includes a plurality of dielectric resonators arranged at intervals along at least one of the two directions. heating device.