JPS6035196Y2 - microwave oven - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a microwave oven having a heating chamber, and particularly aims to effectively suppress radio wave leakage from around the opening of the heating chamber.

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 radio wave attenuation groove, for example, a resonant cavity with an input/4 length (input is the effective wavelength of the leaked radio wave) around the opening of the heating chamber. .

However, although such a radio wave attenuation groove exhibits a deterrent effect on leakage radio waves propagating in the length direction, it has almost no deterrent effect on radio waves having a propagation component in a direction perpendicular to that direction.

In this way, leakage radio waves that cannot be suppressed by the radio wave attenuation groove can be suppressed by providing a periodic structure that serves as a delay circuit, but this is not yet possible.

The present invention has been devised in view of the above points, and will be described below with reference to examples.

In the figure, 1 is a heating chamber, 2 is a metal main body wall that spatially limits the heating chamber, and 3 is a door that opens and closes a rectangular opening in the front of the heating chamber 1.

The door 3 includes a metal door frame 4 and a metal door inner plate 5 fixed to the inner surface of the door frame, and a radio wave attenuation groove 6 is formed on the circumferential surface of the door frame 4 and the door inner plate 5, and the opening thereof is covered with a dielectric cover 7.

The radio wave attenuation groove 6 extends continuously along the entire periphery of the opening of the rectangular heating chamber, and a metal partition wall 8 is established in the groove along the extending direction. Groove 6a and outer groove 6
In particular, the inner groove 6a is divided into the inclined surface 4a of the door frame 4.
It has a yoke cavity structure with the end face being .

On the upper edge of the partition wall 8, cut and raised portions 9, 9, .

The arrangement pitch of such cutting and raising is 172
If the total frequency used is 2450 MHz, it is set to 40 mm, for example.

The length of the cut and raised portion 9 is preferably 2Cjvvn, the widths of both the vertical and horizontal surfaces are preferably 4wn, and the height of the partition wall is set to 27mm.

The array of cut and raised sections 9 constitutes a periodic structure serving as a slow wave circuit, and exhibits a blocking effect on radio waves having components propagating in the direction in which the radio wave attenuation grooves 6 extend.

This cutoff wavelength varies depending on the amount of door opening, that is, the distance between the main body wall 2 and the door inner plate 5, but the door is usually installed to detect the opening of the door and stop the power supply to the magnetron power circuit. If the minimum door opening amount for the switch to operate effectively is 5 to 6 feet, the door opening amount is 2 to 31 meters.
It is preferable to set the arrangement pitch and dimensions of the cut-and-raised portions 9 so that the cut-off wavelength corresponds to the used radio wave wavelength at time t.

Reference numeral 10 indicates a radio wave absorber such as ferrite bonded to the corner portion of the radio wave attenuation groove 6, and the arrangement of the absorber is a feature of the present invention.

That is, the periodic structure is generally arranged to suppress the leakage of radio waves having a component propagating in the extending direction of the radio wave attenuation groove 6 as described above, but it also prevents radio wave leakage from the corner portions of the radio wave attenuation groove 6. Based on this new knowledge, it has been newly clarified that the radio wave leakage from the corner portions is not so effective as a deterrent effect, and the present invention has been developed to eliminate S was successfully suppressed.

In the above embodiment, it goes without saying that the radio wave attenuation groove 6 including the cut and raised grooves 9 may be provided on the main body wall 2 side.

Thus, according to the present invention, an almost complete suppressing effect can be obtained in the microwave oven leakage radio wave suppressing structure using the radio wave attenuation groove and the periodic structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a perspective view of the main part. DESCRIPTION OF SYMBOLS 1... Heating chamber, 9... Cut-and-raised portion constituting a periodic structure, 10... Radio wave absorber.

Claims (1)

[Scope of utility model registration request] In a microwave oven in which a radio wave attenuation groove is continuously provided along the entire periphery of the opening of a rectangular heating chamber, and a periodic structure serving as a slow wave circuit is arranged in the groove, a radio wave absorber is provided at a corner of the radio wave attenuation groove. A microwave oven characterized by being provided with.