JPS62145687A - Radio frequency heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-frequency heating device, and more particularly to a radio wave leakage prevention structure for an openable and closable door provided at the entrance of a heating chamber of a high-frequency heating device.

A conventional high-frequency heating device heats or cooks food, which is an object to be heated, placed in a heating chamber using high-frequency energy supplied from a magnetron, which is a source of high-frequency radio waves. This high-frequency heating device is equipped with a door that can be opened and closed, but there is a slight gap between the main body of the heating chamber and the door, and radio waves leak from this gap to the outside, causing negative effects on the human body. In consideration of this, it is necessary to suppress the n-wave meter to within the legally permissible value, and for this purpose, a leakage prevention mechanism is provided mainly on the door surface.

As a mechanism for preventing radio wave leakage in general doors.

The choke method, in other words, places a choke structure with radio wave attenuation grooves on the periphery of the door, and the dimensions of the radio wave passage formed by the heating chamber and the door from the groove to the groove.

There is a means to set the width of each groove to /4 of the radio wave wavelength used. This means is equivalent to short-circuiting the entrance of the radio wave path in terms of impedance.

Although it has the advantage of preventing leakage of radio waves, on the other hand, the width of the groove is regulated, which poses a problem in making the door smaller and the entire high-frequency heating device more compact. In addition, there are other radio wave leakage prevention devices such as T77i, for example,
As shown in Japanese Patent No. 7585, a method has been proposed in which a groove sealing plate is extended from the opening of the choke groove and a plurality of slits are formed in this extension.
The width of the choke groove must be 1/4 of the radio wave wavelength used.

It was not possible to respond to the miniaturization of the door. In addition, in various radio wave sealing means that seal leakage radio waves by arranging metal plates with slits, periodic intervals with slits are used. Although the 7 + yen break is arranged closely with the door flange, in reality, in order to prevent the surface of the two-period structure from becoming dirty and to prevent fragments of the heated object from entering the radio wave seal part, It is necessary to cover the radio wave seal part with a dielectric cover of a certain thickness. In addition, even if you do not use a dielectric cover and maintain close contact by applying film coaching or other methods, the coating may be damaged by impact or abrasion caused by opening and closing the door, and the periodic structure and heating chamber may be damaged. Metallic contact occurs between the opening peripheries of the two, generating sparks between the two.Therefore, in order to prevent this problem, it is necessary to interpose a dielectric cover that electrically isolates the two.These dielectric The body cover also prevents the door from forming into an 'IX' shape.

The problem to be solved by the invention is that the size of the choke groove, dielectric cover, etc. makes it impossible to downsize the door.

Means for Solving the Problems The present invention provides a groove (hereinafter referred to as a groove) surrounded by metal having a substantially U-shaped cross section at the periphery as a means for providing the above-mentioned device.
The opening of the groove is opened opposite the opening peripheral wall of the heating chamber (opening flange part or sash plate part), and the width of the groove is set in this opening. By periodically arranging periodic structures in the shape of a flat plate with a notch at the tip covering more than half of the groove in the longitudinal direction of the groove, and selecting optimal conditions such as the width of each periodic structure and the arrangement pitch, radio waves can be transmitted. The purpose is to make the high-frequency heating device more compact by configuring a small door with a small amount of leakage.

Function The function of the present invention is that the size of the notch formed at the tip of the flat periodic structure constituting the transmission line for leakage radio waves is 1' per circumference.
J! By changing the width, overall length, arrangement pitch, etc. of the base portion of the structure, the impedance when looking inside from the opening of the groove becomes open, and leakage radio waves are reduced through repeated multiple reflections.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the appearance of the high-frequency heating device of the present invention. In the figure, 1 is a heating chamber that stores objects to be heated, and 2 is a cabinet that surrounds the heating chamber 1.

The front edge of the cabinet 2 is an extension of the metal plate forming the cabinet 2 and surrounds the door 3.

A sash plate 4'z that is a part of the opening peripheral wall of the heating chamber 1
is forming. Reference numeral 5 denotes a flange portion 110 that surrounds the entire circumference of the opening of the heat chamber 1, and constitutes another part of the peripheral wall of the opening of the heating chamber. Reference numeral 6 denotes an operation section and display section for operating the high-frequency heating device, 7 a door handle, and 8 a viewing window. FIG. 2 is a cross-sectional view showing one embodiment of the high-frequency heating device of the present invention, and FIG. 6 is an enlarged perspective view of the main part of FIG. 2. The same parts as in Figure 1 are indicated by the same numbers. As shown in the figure, heating chamber 1
A portion of the wall 9 is bent to form a flange.

There is an upright sash plate 4 in its extension, and this sash plate 4 and the flange portion constitute a heating chamber opening peripheral wall 5 that supports the door.

In front of the flange portion, radio wave seal portions disposed on the peripheral edge of the door body 3 are placed facing each other, and the two are partially in contact with each other. The radio wave seal mechanism includes a groove formed of metal and a plurality of periodic structures that cover the opening surface of the groove. That is, on the periphery of the door body 6, there is a metal groove 10 having a substantially U-shaped cross section, forming a groove space 11. The width t1 of the groove 10 is 1/4 (approximately 30 +
mn) to a narrower 1/6 wavelength. The depth of the grooves should also be the same. Further, the opening 12 of the groove 10 is open toward the opening peripheral wall 5.

There is a flat end face 13 on the heating chamber side of the upper end of the groove 10, and on this end face 13 there is a viewing window 8 made of punched metal and a glass cover (not shown). Reference numeral 14 denotes a door rear plate, which is supported on the end surface 13 together with the peripheral edge of the viewing window 8 by screws at a support portion 15 . This door back plate 14 also surrounds the base portion of the periodic structure 17! The structure 17 constitutes the main body portion. That is, the door back plate 14 has a flat portion 16 and a portion that constitutes a one-edge structure 17. A notch 18 (18a, 18b) is provided at the tip of the flat circumferential structure 17.

18c, 18d, +8e). The boundary surface 19 between the flat portion 16 and the periodic structure 17 is sharpened to match the end surface of the opening of the groove, and this boundary surface 19 is provided with a step so that the lower side, that is, the periodic structure A dielectric cover 20 is placed over the groove 17 and covers the groove opening 12 and the outer periphery of the groove (not shown). 21 is the bottom surface of the groove.

Next, in order to generate excellent radio wave sealing performance with the structure shown in Figure 3, we will introduce the structure of the 0-cycle, 1-hi-1 structure! l + all, Figure 4 (
This will be explained with reference to the partially enlarged view of FIG. 6). The first is the width t2 of the periodic structure 17, and this tl is set to be approximately 1/4 smaller than the wavelength of the radio waves used.

The second is the length t3 of the periodic structure, and this t3 is the length of the groove 1.
= L 5C to 80% of tl, although it varies depending on l
When the condition is met, the radio wave seal effect is -1! : is large. The third is the length of the blue-tinted arrangement interval t4, but if you provide an interval of 1/6 to 1/12 of the radio wave wavelength used, the radio wave seal Highly effective. Also, P =
The period jjjl 1':'F structure arrangement period expressed as tl + l< is required to have a length approximately 1/4 of the radio wave wavelength used.

Next, a notch 1B formed at the tip of the periodic structure 17
Talk about the shape of. In Fig. 4, +Z5 is the length of notch j'714, and t6 is the first notch ffl<
18a is the notch width, and t7 is the notch width of the second notch portion 18b.

Let t6=t7. t8 is the width of the non-cut portion. Here, the groove width is 1. + 62 = 1/6 wavelength, t
Let 3 be 80% of 11, and t, and p each be 1/6
, 1/4 wavelength, t5 is preferably 1/2 of t3. Under these conditions, the relationship between the width t8 of the non-cut portion and the leakage air is as shown in Figure 5, and when the width of one periodic structure is cut out so that about 1/2 remains, the amount of leakage is the smallest. Become. By gradually varying the notch dimensions in this way, the amount of leakage can be controlled and minimized, so the biggest advantage is that it increases the degree of freedom in door design. .

Effects of the Invention As described above, according to the present invention, as a door component in a high frequency heating device, the groove width is 1/4 of the radio wave wavelength used.
A leaky transmission line is formed by installing a narrower groove and arranging plate-shaped periodic structures having a notch at the tip so as to cover 1/2 or more of the opening of this groove,
The transmission lines are arranged at intervals of approximately 1/6 to 1/12 of the radio wave wavelength used in the longitudinal direction of the groove. Same array period <1/
4, so that the radio waves leaking from the flange part that is the peripheral wall of the opening of the heating chamber and the gap between the sash plate and the door can be suppressed to an extremely low level.

It has the advantage of providing a safe high-frequency heating device.

Furthermore, in this radio wave sealing means, the leakage prevention effect can be achieved even if not only the width of the groove but also the depth of the groove is smaller than 1/4 of the radio wave wavelength used, so it is possible to make the door smaller and the high frequency heating device more compact. It has the advantages that can be realized.

Note that the same effect can be obtained even when the radio wave sealing means according to the present invention is provided on the wall surface of the heating chamber.

In addition, although the shape of the notch in the periodic structure is at right angles in the embodiment, even if the corners of the notch and the remaining portion are rounded, the radio wave sealing effect will not be impaired, so the workability will be improved. can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the external appearance of a high-frequency heating device according to an embodiment of the present invention, FIG. 2 is a sectional view of the high-frequency heating device according to an embodiment of the present invention, and FIG. FIG. 4 is a schematic diagram for explaining the structural conditions of the periodic structure, and FIG. 5 is a characteristic diagram for explaining the present invention. 1... Heating chamber. 6...door. 5...Opening peripheral wall. 10...Groove. 1z...Groove opening. 17...Period + R structure. 18...Circumference: 1υj groove structure notch. t4...Sequence interval. P...Sequence period.

Claims (1)

[Claims] In a heating chamber that stores an object to be heated and a door that can be opened and closed at the opening of the heating chamber, over the entire circumference of at least one of the periphery of the door (3) or the wall surface of the heating chamber facing the door (3), A groove (10) having a width narrower than approximately 1/4 of the radio wave wavelength used is installed, and an opening (12) of this groove (10) is installed.
A periodic structure (17) having a flat plate shape and a notch (18) formed at the tip is arranged at an interval (l_4) along the length of the groove (10) approximately 1/6 of the radio wave wavelength used. ~
A high-frequency heating device characterized in that the high-frequency heating device is periodically installed so that the arrangement period (P) is 1/12 and the arrangement period (P) is 1/4.