JPS6157531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a door for a microwave oven.

Conventionally, various structures have been considered for this type of microwave oven door, but the structure shown in FIG. 3 is basically the one that is currently in general practical use.

The structure of this door is that the door body 1 is made by drawing and welding a steel plate approximately 1 mm thick, and a chiyoke groove 2 is formed on the inner peripheral edge of the door body 1 to enhance the effect of preventing radio wave leakage. Periodic structure 2 in chiyoke groove 2
1 is provided. Then, cover the chiyoke groove 2 with a chiyoke cover 22, sandwich the metal see-through screen 5 between two glass plates 23, and electrically connect a sheet metal backing plate 24 with a thickness of about 1 mm to the door body 1 with a plurality of screws 25. It was fixed in contact.

Further, a seal 26 made of silicone rubber is provided around the periphery of the glass plate 23 on the side of the sheet metal backing plate 24 to prevent moisture from entering the inside of the door body 1.
In addition to these members, handles, hinges, etc. are required to complete the microwave oven door, but they are omitted because they are not related to the gist of the present invention.

Furthermore, if design is ignored for the door of an electric heating oven or the like, a single glass plate and a handle are sufficient, but for a door for a microwave oven, the door becomes complicated as shown in Figure 3. This is because a radio wave leakage prevention mechanism is required, and a chiyoke groove 2 is provided on the inner peripheral edge of the door body 1, and a quarter-wavelength chiyoke is formed with a sheet metal backing plate 24.

Further, a check cover 22 provided in the check groove 2 prevents dirt, water, etc. from entering the door body 1. Further, the periodic structure 21 enhances the effect of preventing radio wave leakage, and the same effect can be obtained by providing slits at equal intervals on the outer periphery of the sheet metal backing plate 24 instead of the periodic structure 21. However, since the mechanical strength is weakened, it is not currently practiced except in special cases.

In addition, the see-through screen 5 is generally made by punching numerous small holes of about 1 mm in diameter in a steel plate with a thickness of about 0.2 mm, and has an aperture ratio of 50% or more. It is protected by plate glass 23. In order to obtain the mechanical strength of this see-through screen 5, it is difficult to achieve an aperture ratio of 50% by making the plate thickness 1 mm and the diameter of the small holes about 1 mm. Even if it were possible, the aperture ratio would inevitably decrease when viewed from an angle. For example, diameter 4mm
If an attempt was made to secure an aperture ratio of 50% or more by providing large holes, there were drawbacks such as extremely large radio wave leakage.

The present invention includes a door body, a chiyoke groove provided in the inner peripheral edge of the door body, a dielectric material provided in the chiyoke groove, an opening provided in the center of the door body, and a a see-through window made of a transparent dielectric; a metal see-through screen provided on the inside of the door body facing the see-through window and having numerous small holes; and a rear side of the see-through screen. and a cover made of a transparent dielectric material, which is located on the door body, and the transparent screen and the cover are brought into close contact with each other, thereby solving the above-mentioned conventional drawbacks.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Note that the same members as in the conventional example will be described with the same reference numerals.

FIG. 1 shows an exploded perspective view of the door. In Fig. 1, 1 is the door body, which is formed by drawing a magnetic thin metal plate, such as a stainless steel SUS-430 plate with a thickness of 1 mm, to form two chiyoke grooves with a substantially U-shaped cross section on the inner periphery. However, a substantially rectangular opening 3 is provided in the center. Reference numeral 4 denotes a dielectric material inserted into the 2nd portion of the chiyoke groove, which is made of a lightly colored transparent polypropylene resin. 5 is dielectric 4
A metal see-through screen that suppresses the thickness of the
The external dimension is 0.2 mm, slightly smaller than the door body 1, and the outer periphery is provided with slits 6 at equal intervals, and the center is provided with countless small holes 7 with a diameter of about 1 mm by punching. The range of the small holes 7 provided in the see-through screen 5 is slightly smaller than the opening 3 of the door body 1, and is configured such that the aperture ratio of the opening 3 is 50% or more. A cover 8 is made of the same material as the dielectric 4, has a thickness of 0.5 mm, and has the same external dimensions as the door body 1. Reference numeral 9 denotes a see-through window provided on the opposite side of the cover 8 through the see-through screen 5, that is, at the opening 3 of the door body 1.

When assembling a door with such a configuration, the dielectric 4 is placed in the 2nd part of the chiyoke groove of the door body 1,
A metal see-through screen 5 is welded to the inner surface of the door body 1. Then, a transparent polypropylene resin cover 8 is placed inside the see-through screen 5, and a see-through window 9 made of the same material is placed in the opening 3 of the door body 1, and electromagnetic induction heating is performed. is melted to form a plurality of holes 10 in the chiyoke groove portion 2.
The cover 8 is welded to the see-through screen 5, and the see-through window 9 is welded to the opening 3 of the door body 1 and the see-through screen 5 to complete the process.

In this way, connect the 2nd part of the chiyoke groove of the door body 1 to the dielectric 4.
, it is possible to reduce the dimensions of the two portions of the chiyoke grooves in approximately proportion to the square root of the dielectric constant of the dielectric material 4, so it is possible to reduce the size of the door body 1 or to reduce the size of the opening portion 3 of the door body 1. It becomes possible to expand the opening area, and the design of the door body 1 becomes easy.

In addition, since the cover 8 provided on the door body 1 is welded to the see-through screen 5 and the see-through window 9, the cover 8
Also, the mechanical strength of the transparent screen 5 can be improved.

Further, by providing the slits 6 on the outer periphery of the transparent screen 5, the effect of preventing radio wave leakage is further improved.

Furthermore, there is no need to provide a gasket 26 made of silicone rubber or the like around the periphery of the glass plate 23 as in the conventional case, and the sheet metal backing plate 24 is attached to the door body 1 using a plurality of screws 25.
It also eliminates the man-hours required for installation, resulting in significant cost reductions.

As is clear from the above description, the microwave oven door of the present invention has a dielectric material provided in the chiyoke groove provided on the inner peripheral edge of the door body, so that the dielectric constant is approximately proportional to the square root of the permittivity of the dielectric material. Since the dimensions of each of the yoke grooves can be reduced, the design of the door becomes very easy.

Furthermore, it is possible to attach a cover made of a transparent dielectric material to the see-through screen provided on the inner surface of the door body, and to adhere the dielectric material that makes up the see-through window to the see-through screen and the opening of the door body using electromagnetic induction heating. , it is possible to simplify assembly man-hours and reduce the number of parts, and to realize a microwave oven door that saves resources, is low cost, and does not leak radio waves.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of a microwave oven door showing an embodiment of the present invention, Fig. 2 is a side sectional view showing the main parts, and Fig. 3 is an exploded view of a microwave oven door showing a conventional example. FIG. DESCRIPTION OF SYMBOLS 1... Door body, 2... Chiyoke groove, 3... Opening, 4... Dielectric, 5... Transparent screen, 8...
...Cover, 9...See-through window.

Claims (1)

[Claims] 1. A metal door body, a chiyoke groove provided in the inner peripheral edge of the door body, a first transparent dielectric provided in the chiyoke groove, and a metal see-through window provided in the central part of the door body. and second and third transparent dielectrics provided on both sides of the metal transparent window,
The first to third transparent dielectrics flow into the plurality of holes provided on the side surface of the center side of the chiyoke groove and into the small holes made in the metal transparent window, thereby forming the door body. A microwave oven door characterized by being fixed.